Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * random.c -- A strong random number generator |
| 3 | * |
Matt Mackall | 9e95ce2 | 2005-04-16 15:25:56 -0700 | [diff] [blame] | 4 | * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 5 | * |
| 6 | * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All |
| 7 | * rights reserved. |
| 8 | * |
| 9 | * Redistribution and use in source and binary forms, with or without |
| 10 | * modification, are permitted provided that the following conditions |
| 11 | * are met: |
| 12 | * 1. Redistributions of source code must retain the above copyright |
| 13 | * notice, and the entire permission notice in its entirety, |
| 14 | * including the disclaimer of warranties. |
| 15 | * 2. Redistributions in binary form must reproduce the above copyright |
| 16 | * notice, this list of conditions and the following disclaimer in the |
| 17 | * documentation and/or other materials provided with the distribution. |
| 18 | * 3. The name of the author may not be used to endorse or promote |
| 19 | * products derived from this software without specific prior |
| 20 | * written permission. |
| 21 | * |
| 22 | * ALTERNATIVELY, this product may be distributed under the terms of |
| 23 | * the GNU General Public License, in which case the provisions of the GPL are |
| 24 | * required INSTEAD OF the above restrictions. (This clause is |
| 25 | * necessary due to a potential bad interaction between the GPL and |
| 26 | * the restrictions contained in a BSD-style copyright.) |
| 27 | * |
| 28 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| 29 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 30 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF |
| 31 | * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE |
| 32 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 33 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT |
| 34 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR |
| 35 | * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| 36 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 37 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE |
| 38 | * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH |
| 39 | * DAMAGE. |
| 40 | */ |
| 41 | |
| 42 | /* |
| 43 | * (now, with legal B.S. out of the way.....) |
| 44 | * |
| 45 | * This routine gathers environmental noise from device drivers, etc., |
| 46 | * and returns good random numbers, suitable for cryptographic use. |
| 47 | * Besides the obvious cryptographic uses, these numbers are also good |
| 48 | * for seeding TCP sequence numbers, and other places where it is |
| 49 | * desirable to have numbers which are not only random, but hard to |
| 50 | * predict by an attacker. |
| 51 | * |
| 52 | * Theory of operation |
| 53 | * =================== |
| 54 | * |
| 55 | * Computers are very predictable devices. Hence it is extremely hard |
| 56 | * to produce truly random numbers on a computer --- as opposed to |
| 57 | * pseudo-random numbers, which can easily generated by using a |
| 58 | * algorithm. Unfortunately, it is very easy for attackers to guess |
| 59 | * the sequence of pseudo-random number generators, and for some |
| 60 | * applications this is not acceptable. So instead, we must try to |
| 61 | * gather "environmental noise" from the computer's environment, which |
| 62 | * must be hard for outside attackers to observe, and use that to |
| 63 | * generate random numbers. In a Unix environment, this is best done |
| 64 | * from inside the kernel. |
| 65 | * |
| 66 | * Sources of randomness from the environment include inter-keyboard |
| 67 | * timings, inter-interrupt timings from some interrupts, and other |
| 68 | * events which are both (a) non-deterministic and (b) hard for an |
| 69 | * outside observer to measure. Randomness from these sources are |
| 70 | * added to an "entropy pool", which is mixed using a CRC-like function. |
| 71 | * This is not cryptographically strong, but it is adequate assuming |
| 72 | * the randomness is not chosen maliciously, and it is fast enough that |
| 73 | * the overhead of doing it on every interrupt is very reasonable. |
| 74 | * As random bytes are mixed into the entropy pool, the routines keep |
| 75 | * an *estimate* of how many bits of randomness have been stored into |
| 76 | * the random number generator's internal state. |
| 77 | * |
| 78 | * When random bytes are desired, they are obtained by taking the SHA |
| 79 | * hash of the contents of the "entropy pool". The SHA hash avoids |
| 80 | * exposing the internal state of the entropy pool. It is believed to |
| 81 | * be computationally infeasible to derive any useful information |
| 82 | * about the input of SHA from its output. Even if it is possible to |
| 83 | * analyze SHA in some clever way, as long as the amount of data |
| 84 | * returned from the generator is less than the inherent entropy in |
| 85 | * the pool, the output data is totally unpredictable. For this |
| 86 | * reason, the routine decreases its internal estimate of how many |
| 87 | * bits of "true randomness" are contained in the entropy pool as it |
| 88 | * outputs random numbers. |
| 89 | * |
| 90 | * If this estimate goes to zero, the routine can still generate |
| 91 | * random numbers; however, an attacker may (at least in theory) be |
| 92 | * able to infer the future output of the generator from prior |
| 93 | * outputs. This requires successful cryptanalysis of SHA, which is |
| 94 | * not believed to be feasible, but there is a remote possibility. |
| 95 | * Nonetheless, these numbers should be useful for the vast majority |
| 96 | * of purposes. |
| 97 | * |
| 98 | * Exported interfaces ---- output |
| 99 | * =============================== |
| 100 | * |
| 101 | * There are three exported interfaces; the first is one designed to |
| 102 | * be used from within the kernel: |
| 103 | * |
| 104 | * void get_random_bytes(void *buf, int nbytes); |
| 105 | * |
| 106 | * This interface will return the requested number of random bytes, |
| 107 | * and place it in the requested buffer. |
| 108 | * |
| 109 | * The two other interfaces are two character devices /dev/random and |
| 110 | * /dev/urandom. /dev/random is suitable for use when very high |
| 111 | * quality randomness is desired (for example, for key generation or |
| 112 | * one-time pads), as it will only return a maximum of the number of |
| 113 | * bits of randomness (as estimated by the random number generator) |
| 114 | * contained in the entropy pool. |
| 115 | * |
| 116 | * The /dev/urandom device does not have this limit, and will return |
| 117 | * as many bytes as are requested. As more and more random bytes are |
| 118 | * requested without giving time for the entropy pool to recharge, |
| 119 | * this will result in random numbers that are merely cryptographically |
| 120 | * strong. For many applications, however, this is acceptable. |
| 121 | * |
| 122 | * Exported interfaces ---- input |
| 123 | * ============================== |
| 124 | * |
| 125 | * The current exported interfaces for gathering environmental noise |
| 126 | * from the devices are: |
| 127 | * |
Linus Torvalds | a2080a6 | 2012-07-04 11:16:01 -0400 | [diff] [blame] | 128 | * void add_device_randomness(const void *buf, unsigned int size); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 129 | * void add_input_randomness(unsigned int type, unsigned int code, |
| 130 | * unsigned int value); |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 131 | * void add_interrupt_randomness(int irq, int irq_flags); |
Jarod Wilson | 442a4ff | 2011-02-21 21:43:10 +1100 | [diff] [blame] | 132 | * void add_disk_randomness(struct gendisk *disk); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 133 | * |
Linus Torvalds | a2080a6 | 2012-07-04 11:16:01 -0400 | [diff] [blame] | 134 | * add_device_randomness() is for adding data to the random pool that |
| 135 | * is likely to differ between two devices (or possibly even per boot). |
| 136 | * This would be things like MAC addresses or serial numbers, or the |
| 137 | * read-out of the RTC. This does *not* add any actual entropy to the |
| 138 | * pool, but it initializes the pool to different values for devices |
| 139 | * that might otherwise be identical and have very little entropy |
| 140 | * available to them (particularly common in the embedded world). |
| 141 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 142 | * add_input_randomness() uses the input layer interrupt timing, as well as |
| 143 | * the event type information from the hardware. |
| 144 | * |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 145 | * add_interrupt_randomness() uses the interrupt timing as random |
| 146 | * inputs to the entropy pool. Using the cycle counters and the irq source |
| 147 | * as inputs, it feeds the randomness roughly once a second. |
Jarod Wilson | 442a4ff | 2011-02-21 21:43:10 +1100 | [diff] [blame] | 148 | * |
| 149 | * add_disk_randomness() uses what amounts to the seek time of block |
| 150 | * layer request events, on a per-disk_devt basis, as input to the |
| 151 | * entropy pool. Note that high-speed solid state drives with very low |
| 152 | * seek times do not make for good sources of entropy, as their seek |
| 153 | * times are usually fairly consistent. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 154 | * |
| 155 | * All of these routines try to estimate how many bits of randomness a |
| 156 | * particular randomness source. They do this by keeping track of the |
| 157 | * first and second order deltas of the event timings. |
| 158 | * |
| 159 | * Ensuring unpredictability at system startup |
| 160 | * ============================================ |
| 161 | * |
| 162 | * When any operating system starts up, it will go through a sequence |
| 163 | * of actions that are fairly predictable by an adversary, especially |
| 164 | * if the start-up does not involve interaction with a human operator. |
| 165 | * This reduces the actual number of bits of unpredictability in the |
| 166 | * entropy pool below the value in entropy_count. In order to |
| 167 | * counteract this effect, it helps to carry information in the |
| 168 | * entropy pool across shut-downs and start-ups. To do this, put the |
| 169 | * following lines an appropriate script which is run during the boot |
| 170 | * sequence: |
| 171 | * |
| 172 | * echo "Initializing random number generator..." |
| 173 | * random_seed=/var/run/random-seed |
| 174 | * # Carry a random seed from start-up to start-up |
| 175 | * # Load and then save the whole entropy pool |
| 176 | * if [ -f $random_seed ]; then |
| 177 | * cat $random_seed >/dev/urandom |
| 178 | * else |
| 179 | * touch $random_seed |
| 180 | * fi |
| 181 | * chmod 600 $random_seed |
| 182 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 |
| 183 | * |
| 184 | * and the following lines in an appropriate script which is run as |
| 185 | * the system is shutdown: |
| 186 | * |
| 187 | * # Carry a random seed from shut-down to start-up |
| 188 | * # Save the whole entropy pool |
| 189 | * echo "Saving random seed..." |
| 190 | * random_seed=/var/run/random-seed |
| 191 | * touch $random_seed |
| 192 | * chmod 600 $random_seed |
| 193 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 |
| 194 | * |
| 195 | * For example, on most modern systems using the System V init |
| 196 | * scripts, such code fragments would be found in |
| 197 | * /etc/rc.d/init.d/random. On older Linux systems, the correct script |
| 198 | * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0. |
| 199 | * |
| 200 | * Effectively, these commands cause the contents of the entropy pool |
| 201 | * to be saved at shut-down time and reloaded into the entropy pool at |
| 202 | * start-up. (The 'dd' in the addition to the bootup script is to |
| 203 | * make sure that /etc/random-seed is different for every start-up, |
| 204 | * even if the system crashes without executing rc.0.) Even with |
| 205 | * complete knowledge of the start-up activities, predicting the state |
| 206 | * of the entropy pool requires knowledge of the previous history of |
| 207 | * the system. |
| 208 | * |
| 209 | * Configuring the /dev/random driver under Linux |
| 210 | * ============================================== |
| 211 | * |
| 212 | * The /dev/random driver under Linux uses minor numbers 8 and 9 of |
| 213 | * the /dev/mem major number (#1). So if your system does not have |
| 214 | * /dev/random and /dev/urandom created already, they can be created |
| 215 | * by using the commands: |
| 216 | * |
| 217 | * mknod /dev/random c 1 8 |
| 218 | * mknod /dev/urandom c 1 9 |
| 219 | * |
| 220 | * Acknowledgements: |
| 221 | * ================= |
| 222 | * |
| 223 | * Ideas for constructing this random number generator were derived |
| 224 | * from Pretty Good Privacy's random number generator, and from private |
| 225 | * discussions with Phil Karn. Colin Plumb provided a faster random |
| 226 | * number generator, which speed up the mixing function of the entropy |
| 227 | * pool, taken from PGPfone. Dale Worley has also contributed many |
| 228 | * useful ideas and suggestions to improve this driver. |
| 229 | * |
| 230 | * Any flaws in the design are solely my responsibility, and should |
| 231 | * not be attributed to the Phil, Colin, or any of authors of PGP. |
| 232 | * |
| 233 | * Further background information on this topic may be obtained from |
| 234 | * RFC 1750, "Randomness Recommendations for Security", by Donald |
| 235 | * Eastlake, Steve Crocker, and Jeff Schiller. |
| 236 | */ |
| 237 | |
| 238 | #include <linux/utsname.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 239 | #include <linux/module.h> |
| 240 | #include <linux/kernel.h> |
| 241 | #include <linux/major.h> |
| 242 | #include <linux/string.h> |
| 243 | #include <linux/fcntl.h> |
| 244 | #include <linux/slab.h> |
| 245 | #include <linux/random.h> |
| 246 | #include <linux/poll.h> |
| 247 | #include <linux/init.h> |
| 248 | #include <linux/fs.h> |
| 249 | #include <linux/genhd.h> |
| 250 | #include <linux/interrupt.h> |
Andrea Righi | 27ac792 | 2008-07-23 21:28:13 -0700 | [diff] [blame] | 251 | #include <linux/mm.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 252 | #include <linux/spinlock.h> |
Torsten Duwe | c84dbf6 | 2014-06-14 23:38:36 -0400 | [diff] [blame] | 253 | #include <linux/kthread.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 254 | #include <linux/percpu.h> |
| 255 | #include <linux/cryptohash.h> |
Neil Horman | 5b739ef | 2009-06-18 19:50:21 +0800 | [diff] [blame] | 256 | #include <linux/fips.h> |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 257 | #include <linux/ptrace.h> |
Theodore Ts'o | e6d4947 | 2012-07-05 10:21:01 -0400 | [diff] [blame] | 258 | #include <linux/kmemcheck.h> |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 259 | #include <linux/workqueue.h> |
Martin Schwidefsky | 0244ad0 | 2013-08-30 09:39:53 +0200 | [diff] [blame] | 260 | #include <linux/irq.h> |
Theodore Ts'o | c6e9d6f | 2014-07-17 04:13:05 -0400 | [diff] [blame] | 261 | #include <linux/syscalls.h> |
| 262 | #include <linux/completion.h> |
Andy Shevchenko | 8da4b8c | 2016-05-20 17:01:00 -0700 | [diff] [blame] | 263 | #include <linux/uuid.h> |
Yinghai Lu | d178a1e | 2009-01-11 00:35:42 -0800 | [diff] [blame] | 264 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 265 | #include <asm/processor.h> |
| 266 | #include <asm/uaccess.h> |
| 267 | #include <asm/irq.h> |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 268 | #include <asm/irq_regs.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 269 | #include <asm/io.h> |
| 270 | |
Theodore Ts'o | 00ce1db | 2012-07-04 16:19:30 -0400 | [diff] [blame] | 271 | #define CREATE_TRACE_POINTS |
| 272 | #include <trace/events/random.h> |
| 273 | |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 274 | /* #define ADD_INTERRUPT_BENCH */ |
| 275 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 276 | /* |
| 277 | * Configuration information |
| 278 | */ |
H. Peter Anvin | 30e37ec | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 279 | #define INPUT_POOL_SHIFT 12 |
| 280 | #define INPUT_POOL_WORDS (1 << (INPUT_POOL_SHIFT-5)) |
| 281 | #define OUTPUT_POOL_SHIFT 10 |
| 282 | #define OUTPUT_POOL_WORDS (1 << (OUTPUT_POOL_SHIFT-5)) |
| 283 | #define SEC_XFER_SIZE 512 |
| 284 | #define EXTRACT_SIZE 10 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 285 | |
Theodore Ts'o | 392a546 | 2013-11-03 18:24:08 -0500 | [diff] [blame] | 286 | #define DEBUG_RANDOM_BOOT 0 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 287 | |
H. Peter Anvin | d2e7c96 | 2012-07-27 22:26:08 -0400 | [diff] [blame] | 288 | #define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long)) |
| 289 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 290 | /* |
Theodore Ts'o | 95b709b | 2013-10-02 21:10:35 -0400 | [diff] [blame] | 291 | * To allow fractional bits to be tracked, the entropy_count field is |
| 292 | * denominated in units of 1/8th bits. |
H. Peter Anvin | 30e37ec | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 293 | * |
| 294 | * 2*(ENTROPY_SHIFT + log2(poolbits)) must <= 31, or the multiply in |
| 295 | * credit_entropy_bits() needs to be 64 bits wide. |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 296 | */ |
| 297 | #define ENTROPY_SHIFT 3 |
| 298 | #define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT) |
| 299 | |
| 300 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 301 | * The minimum number of bits of entropy before we wake up a read on |
| 302 | * /dev/random. Should be enough to do a significant reseed. |
| 303 | */ |
Greg Price | 2132a96 | 2013-12-06 21:28:03 -0500 | [diff] [blame] | 304 | static int random_read_wakeup_bits = 64; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 305 | |
| 306 | /* |
| 307 | * If the entropy count falls under this number of bits, then we |
| 308 | * should wake up processes which are selecting or polling on write |
| 309 | * access to /dev/random. |
| 310 | */ |
Greg Price | 2132a96 | 2013-12-06 21:28:03 -0500 | [diff] [blame] | 311 | static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 312 | |
| 313 | /* |
Greg Price | dfd3875 | 2013-11-29 14:58:06 -0500 | [diff] [blame] | 314 | * The minimum number of seconds between urandom pool reseeding. We |
Theodore Ts'o | f5c2742 | 2013-09-22 15:14:32 -0400 | [diff] [blame] | 315 | * do this to limit the amount of entropy that can be drained from the |
| 316 | * input pool even if there are heavy demands on /dev/urandom. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 317 | */ |
Theodore Ts'o | f5c2742 | 2013-09-22 15:14:32 -0400 | [diff] [blame] | 318 | static int random_min_urandom_seed = 60; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 319 | |
| 320 | /* |
Theodore Ts'o | 6e9fa2c | 2013-09-22 16:04:19 -0400 | [diff] [blame] | 321 | * Originally, we used a primitive polynomial of degree .poolwords |
| 322 | * over GF(2). The taps for various sizes are defined below. They |
| 323 | * were chosen to be evenly spaced except for the last tap, which is 1 |
| 324 | * to get the twisting happening as fast as possible. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 325 | * |
Theodore Ts'o | 6e9fa2c | 2013-09-22 16:04:19 -0400 | [diff] [blame] | 326 | * For the purposes of better mixing, we use the CRC-32 polynomial as |
| 327 | * well to make a (modified) twisted Generalized Feedback Shift |
| 328 | * Register. (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR |
| 329 | * generators. ACM Transactions on Modeling and Computer Simulation |
| 330 | * 2(3):179-194. Also see M. Matsumoto & Y. Kurita, 1994. Twisted |
Greg Price | dfd3875 | 2013-11-29 14:58:06 -0500 | [diff] [blame] | 331 | * GFSR generators II. ACM Transactions on Modeling and Computer |
Theodore Ts'o | 6e9fa2c | 2013-09-22 16:04:19 -0400 | [diff] [blame] | 332 | * Simulation 4:254-266) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 333 | * |
| 334 | * Thanks to Colin Plumb for suggesting this. |
| 335 | * |
Theodore Ts'o | 6e9fa2c | 2013-09-22 16:04:19 -0400 | [diff] [blame] | 336 | * The mixing operation is much less sensitive than the output hash, |
| 337 | * where we use SHA-1. All that we want of mixing operation is that |
| 338 | * it be a good non-cryptographic hash; i.e. it not produce collisions |
| 339 | * when fed "random" data of the sort we expect to see. As long as |
| 340 | * the pool state differs for different inputs, we have preserved the |
| 341 | * input entropy and done a good job. The fact that an intelligent |
| 342 | * attacker can construct inputs that will produce controlled |
| 343 | * alterations to the pool's state is not important because we don't |
| 344 | * consider such inputs to contribute any randomness. The only |
| 345 | * property we need with respect to them is that the attacker can't |
| 346 | * increase his/her knowledge of the pool's state. Since all |
| 347 | * additions are reversible (knowing the final state and the input, |
| 348 | * you can reconstruct the initial state), if an attacker has any |
| 349 | * uncertainty about the initial state, he/she can only shuffle that |
| 350 | * uncertainty about, but never cause any collisions (which would |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 351 | * decrease the uncertainty). |
| 352 | * |
Theodore Ts'o | 6e9fa2c | 2013-09-22 16:04:19 -0400 | [diff] [blame] | 353 | * Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and |
| 354 | * Videau in their paper, "The Linux Pseudorandom Number Generator |
| 355 | * Revisited" (see: http://eprint.iacr.org/2012/251.pdf). In their |
| 356 | * paper, they point out that we are not using a true Twisted GFSR, |
| 357 | * since Matsumoto & Kurita used a trinomial feedback polynomial (that |
| 358 | * is, with only three taps, instead of the six that we are using). |
| 359 | * As a result, the resulting polynomial is neither primitive nor |
| 360 | * irreducible, and hence does not have a maximal period over |
| 361 | * GF(2**32). They suggest a slight change to the generator |
| 362 | * polynomial which improves the resulting TGFSR polynomial to be |
| 363 | * irreducible, which we have made here. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 364 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 365 | static struct poolinfo { |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 366 | int poolbitshift, poolwords, poolbytes, poolbits, poolfracbits; |
| 367 | #define S(x) ilog2(x)+5, (x), (x)*4, (x)*32, (x) << (ENTROPY_SHIFT+5) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 368 | int tap1, tap2, tap3, tap4, tap5; |
| 369 | } poolinfo_table[] = { |
Theodore Ts'o | 6e9fa2c | 2013-09-22 16:04:19 -0400 | [diff] [blame] | 370 | /* was: x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 */ |
| 371 | /* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */ |
| 372 | { S(128), 104, 76, 51, 25, 1 }, |
| 373 | /* was: x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 */ |
| 374 | /* x^32 + x^26 + x^19 + x^14 + x^7 + x + 1 */ |
| 375 | { S(32), 26, 19, 14, 7, 1 }, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 376 | #if 0 |
| 377 | /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */ |
H. Peter Anvin | 9ed17b7 | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 378 | { S(2048), 1638, 1231, 819, 411, 1 }, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 379 | |
| 380 | /* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */ |
H. Peter Anvin | 9ed17b7 | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 381 | { S(1024), 817, 615, 412, 204, 1 }, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 382 | |
| 383 | /* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */ |
H. Peter Anvin | 9ed17b7 | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 384 | { S(1024), 819, 616, 410, 207, 2 }, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 385 | |
| 386 | /* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */ |
H. Peter Anvin | 9ed17b7 | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 387 | { S(512), 411, 308, 208, 104, 1 }, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 388 | |
| 389 | /* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */ |
H. Peter Anvin | 9ed17b7 | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 390 | { S(512), 409, 307, 206, 102, 2 }, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 391 | /* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */ |
H. Peter Anvin | 9ed17b7 | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 392 | { S(512), 409, 309, 205, 103, 2 }, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 393 | |
| 394 | /* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */ |
H. Peter Anvin | 9ed17b7 | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 395 | { S(256), 205, 155, 101, 52, 1 }, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 396 | |
| 397 | /* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */ |
H. Peter Anvin | 9ed17b7 | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 398 | { S(128), 103, 78, 51, 27, 2 }, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 399 | |
| 400 | /* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */ |
H. Peter Anvin | 9ed17b7 | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 401 | { S(64), 52, 39, 26, 14, 1 }, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 402 | #endif |
| 403 | }; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 404 | |
| 405 | /* |
| 406 | * Static global variables |
| 407 | */ |
| 408 | static DECLARE_WAIT_QUEUE_HEAD(random_read_wait); |
| 409 | static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); |
Theodore Ts'o | c6e9d6f | 2014-07-17 04:13:05 -0400 | [diff] [blame] | 410 | static DECLARE_WAIT_QUEUE_HEAD(urandom_init_wait); |
Jeff Dike | 9a6f70b | 2008-04-29 01:03:08 -0700 | [diff] [blame] | 411 | static struct fasync_struct *fasync; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 412 | |
Herbert Xu | 205a525 | 2015-06-09 18:19:39 +0800 | [diff] [blame] | 413 | static DEFINE_SPINLOCK(random_ready_list_lock); |
| 414 | static LIST_HEAD(random_ready_list); |
| 415 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 416 | /********************************************************************** |
| 417 | * |
| 418 | * OS independent entropy store. Here are the functions which handle |
| 419 | * storing entropy in an entropy pool. |
| 420 | * |
| 421 | **********************************************************************/ |
| 422 | |
| 423 | struct entropy_store; |
| 424 | struct entropy_store { |
Matt Mackall | 4335820 | 2008-04-29 01:03:01 -0700 | [diff] [blame] | 425 | /* read-only data: */ |
H. Peter Anvin | 30e37ec | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 426 | const struct poolinfo *poolinfo; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 427 | __u32 *pool; |
| 428 | const char *name; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 429 | struct entropy_store *pull; |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 430 | struct work_struct push_work; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 431 | |
| 432 | /* read-write data: */ |
Theodore Ts'o | f5c2742 | 2013-09-22 15:14:32 -0400 | [diff] [blame] | 433 | unsigned long last_pulled; |
Matt Mackall | 4335820 | 2008-04-29 01:03:01 -0700 | [diff] [blame] | 434 | spinlock_t lock; |
Theodore Ts'o | c59974a | 2013-09-21 19:42:41 -0400 | [diff] [blame] | 435 | unsigned short add_ptr; |
| 436 | unsigned short input_rotate; |
Matt Mackall | cda796a | 2009-01-06 14:42:55 -0800 | [diff] [blame] | 437 | int entropy_count; |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 438 | int entropy_total; |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 439 | unsigned int initialized:1; |
Theodore Ts'o | c59974a | 2013-09-21 19:42:41 -0400 | [diff] [blame] | 440 | unsigned int limit:1; |
| 441 | unsigned int last_data_init:1; |
Matt Mackall | e954bc9 | 2010-05-20 19:55:01 +1000 | [diff] [blame] | 442 | __u8 last_data[EXTRACT_SIZE]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 443 | }; |
| 444 | |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 445 | static void push_to_pool(struct work_struct *work); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 446 | static __u32 input_pool_data[INPUT_POOL_WORDS]; |
| 447 | static __u32 blocking_pool_data[OUTPUT_POOL_WORDS]; |
| 448 | static __u32 nonblocking_pool_data[OUTPUT_POOL_WORDS]; |
| 449 | |
| 450 | static struct entropy_store input_pool = { |
| 451 | .poolinfo = &poolinfo_table[0], |
| 452 | .name = "input", |
| 453 | .limit = 1, |
Thomas Gleixner | eece09e | 2011-07-17 21:25:03 +0200 | [diff] [blame] | 454 | .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 455 | .pool = input_pool_data |
| 456 | }; |
| 457 | |
| 458 | static struct entropy_store blocking_pool = { |
| 459 | .poolinfo = &poolinfo_table[1], |
| 460 | .name = "blocking", |
| 461 | .limit = 1, |
| 462 | .pull = &input_pool, |
Thomas Gleixner | eece09e | 2011-07-17 21:25:03 +0200 | [diff] [blame] | 463 | .lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock), |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 464 | .pool = blocking_pool_data, |
| 465 | .push_work = __WORK_INITIALIZER(blocking_pool.push_work, |
| 466 | push_to_pool), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 467 | }; |
| 468 | |
| 469 | static struct entropy_store nonblocking_pool = { |
| 470 | .poolinfo = &poolinfo_table[1], |
| 471 | .name = "nonblocking", |
| 472 | .pull = &input_pool, |
Thomas Gleixner | eece09e | 2011-07-17 21:25:03 +0200 | [diff] [blame] | 473 | .lock = __SPIN_LOCK_UNLOCKED(nonblocking_pool.lock), |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 474 | .pool = nonblocking_pool_data, |
| 475 | .push_work = __WORK_INITIALIZER(nonblocking_pool.push_work, |
| 476 | push_to_pool), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 477 | }; |
| 478 | |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 479 | static __u32 const twist_table[8] = { |
| 480 | 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158, |
| 481 | 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 }; |
| 482 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 483 | /* |
Matt Mackall | e68e5b6 | 2008-04-29 01:03:05 -0700 | [diff] [blame] | 484 | * This function adds bytes into the entropy "pool". It does not |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 485 | * update the entropy estimate. The caller should call |
Matt Mackall | adc782d | 2008-04-29 01:03:07 -0700 | [diff] [blame] | 486 | * credit_entropy_bits if this is appropriate. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 487 | * |
| 488 | * The pool is stirred with a primitive polynomial of the appropriate |
| 489 | * degree, and then twisted. We twist by three bits at a time because |
| 490 | * it's cheap to do so and helps slightly in the expected case where |
| 491 | * the entropy is concentrated in the low-order bits. |
| 492 | */ |
Theodore Ts'o | 00ce1db | 2012-07-04 16:19:30 -0400 | [diff] [blame] | 493 | static void _mix_pool_bytes(struct entropy_store *r, const void *in, |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 494 | int nbytes) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 495 | { |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 496 | unsigned long i, tap1, tap2, tap3, tap4, tap5; |
Matt Mackall | feee769 | 2008-04-29 01:03:02 -0700 | [diff] [blame] | 497 | int input_rotate; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 498 | int wordmask = r->poolinfo->poolwords - 1; |
Matt Mackall | e68e5b6 | 2008-04-29 01:03:05 -0700 | [diff] [blame] | 499 | const char *bytes = in; |
Matt Mackall | 6d38b82 | 2008-04-29 01:03:03 -0700 | [diff] [blame] | 500 | __u32 w; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 501 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 502 | tap1 = r->poolinfo->tap1; |
| 503 | tap2 = r->poolinfo->tap2; |
| 504 | tap3 = r->poolinfo->tap3; |
| 505 | tap4 = r->poolinfo->tap4; |
| 506 | tap5 = r->poolinfo->tap5; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 507 | |
Theodore Ts'o | 91fcb53 | 2014-06-10 22:46:37 -0400 | [diff] [blame] | 508 | input_rotate = r->input_rotate; |
| 509 | i = r->add_ptr; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 510 | |
Matt Mackall | e68e5b6 | 2008-04-29 01:03:05 -0700 | [diff] [blame] | 511 | /* mix one byte at a time to simplify size handling and churn faster */ |
| 512 | while (nbytes--) { |
Theodore Ts'o | c59974a | 2013-09-21 19:42:41 -0400 | [diff] [blame] | 513 | w = rol32(*bytes++, input_rotate); |
Matt Mackall | 993ba21 | 2008-04-29 01:03:04 -0700 | [diff] [blame] | 514 | i = (i - 1) & wordmask; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 515 | |
| 516 | /* XOR in the various taps */ |
Matt Mackall | 993ba21 | 2008-04-29 01:03:04 -0700 | [diff] [blame] | 517 | w ^= r->pool[i]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 518 | w ^= r->pool[(i + tap1) & wordmask]; |
| 519 | w ^= r->pool[(i + tap2) & wordmask]; |
| 520 | w ^= r->pool[(i + tap3) & wordmask]; |
| 521 | w ^= r->pool[(i + tap4) & wordmask]; |
| 522 | w ^= r->pool[(i + tap5) & wordmask]; |
Matt Mackall | 993ba21 | 2008-04-29 01:03:04 -0700 | [diff] [blame] | 523 | |
| 524 | /* Mix the result back in with a twist */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 525 | r->pool[i] = (w >> 3) ^ twist_table[w & 7]; |
Matt Mackall | feee769 | 2008-04-29 01:03:02 -0700 | [diff] [blame] | 526 | |
| 527 | /* |
| 528 | * Normally, we add 7 bits of rotation to the pool. |
| 529 | * At the beginning of the pool, add an extra 7 bits |
| 530 | * rotation, so that successive passes spread the |
| 531 | * input bits across the pool evenly. |
| 532 | */ |
Theodore Ts'o | c59974a | 2013-09-21 19:42:41 -0400 | [diff] [blame] | 533 | input_rotate = (input_rotate + (i ? 7 : 14)) & 31; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 534 | } |
| 535 | |
Theodore Ts'o | 91fcb53 | 2014-06-10 22:46:37 -0400 | [diff] [blame] | 536 | r->input_rotate = input_rotate; |
| 537 | r->add_ptr = i; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 538 | } |
| 539 | |
Theodore Ts'o | 00ce1db | 2012-07-04 16:19:30 -0400 | [diff] [blame] | 540 | static void __mix_pool_bytes(struct entropy_store *r, const void *in, |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 541 | int nbytes) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 542 | { |
Theodore Ts'o | 00ce1db | 2012-07-04 16:19:30 -0400 | [diff] [blame] | 543 | trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_); |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 544 | _mix_pool_bytes(r, in, nbytes); |
Theodore Ts'o | 00ce1db | 2012-07-04 16:19:30 -0400 | [diff] [blame] | 545 | } |
| 546 | |
| 547 | static void mix_pool_bytes(struct entropy_store *r, const void *in, |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 548 | int nbytes) |
Theodore Ts'o | 00ce1db | 2012-07-04 16:19:30 -0400 | [diff] [blame] | 549 | { |
Theodore Ts'o | 902c098 | 2012-07-04 10:38:30 -0400 | [diff] [blame] | 550 | unsigned long flags; |
| 551 | |
Theodore Ts'o | 00ce1db | 2012-07-04 16:19:30 -0400 | [diff] [blame] | 552 | trace_mix_pool_bytes(r->name, nbytes, _RET_IP_); |
Theodore Ts'o | 902c098 | 2012-07-04 10:38:30 -0400 | [diff] [blame] | 553 | spin_lock_irqsave(&r->lock, flags); |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 554 | _mix_pool_bytes(r, in, nbytes); |
Theodore Ts'o | 902c098 | 2012-07-04 10:38:30 -0400 | [diff] [blame] | 555 | spin_unlock_irqrestore(&r->lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 556 | } |
| 557 | |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 558 | struct fast_pool { |
| 559 | __u32 pool[4]; |
| 560 | unsigned long last; |
Theodore Ts'o | ee3e00e | 2014-06-15 16:59:24 -0400 | [diff] [blame] | 561 | unsigned short reg_idx; |
Theodore Ts'o | 840f950 | 2014-06-14 03:06:57 -0400 | [diff] [blame] | 562 | unsigned char count; |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 563 | }; |
| 564 | |
| 565 | /* |
| 566 | * This is a fast mixing routine used by the interrupt randomness |
| 567 | * collector. It's hardcoded for an 128 bit pool and assumes that any |
| 568 | * locks that might be needed are taken by the caller. |
| 569 | */ |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 570 | static void fast_mix(struct fast_pool *f) |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 571 | { |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 572 | __u32 a = f->pool[0], b = f->pool[1]; |
| 573 | __u32 c = f->pool[2], d = f->pool[3]; |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 574 | |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 575 | a += b; c += d; |
George Spelvin | 19acc77 | 2015-02-07 00:32:06 -0500 | [diff] [blame] | 576 | b = rol32(b, 6); d = rol32(d, 27); |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 577 | d ^= a; b ^= c; |
Theodore Ts'o | 655b226 | 2013-09-22 15:24:02 -0400 | [diff] [blame] | 578 | |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 579 | a += b; c += d; |
George Spelvin | 19acc77 | 2015-02-07 00:32:06 -0500 | [diff] [blame] | 580 | b = rol32(b, 16); d = rol32(d, 14); |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 581 | d ^= a; b ^= c; |
| 582 | |
| 583 | a += b; c += d; |
George Spelvin | 19acc77 | 2015-02-07 00:32:06 -0500 | [diff] [blame] | 584 | b = rol32(b, 6); d = rol32(d, 27); |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 585 | d ^= a; b ^= c; |
| 586 | |
| 587 | a += b; c += d; |
George Spelvin | 19acc77 | 2015-02-07 00:32:06 -0500 | [diff] [blame] | 588 | b = rol32(b, 16); d = rol32(d, 14); |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 589 | d ^= a; b ^= c; |
| 590 | |
| 591 | f->pool[0] = a; f->pool[1] = b; |
| 592 | f->pool[2] = c; f->pool[3] = d; |
Theodore Ts'o | 655b226 | 2013-09-22 15:24:02 -0400 | [diff] [blame] | 593 | f->count++; |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 594 | } |
| 595 | |
Herbert Xu | 205a525 | 2015-06-09 18:19:39 +0800 | [diff] [blame] | 596 | static void process_random_ready_list(void) |
| 597 | { |
| 598 | unsigned long flags; |
| 599 | struct random_ready_callback *rdy, *tmp; |
| 600 | |
| 601 | spin_lock_irqsave(&random_ready_list_lock, flags); |
| 602 | list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) { |
| 603 | struct module *owner = rdy->owner; |
| 604 | |
| 605 | list_del_init(&rdy->list); |
| 606 | rdy->func(rdy); |
| 607 | module_put(owner); |
| 608 | } |
| 609 | spin_unlock_irqrestore(&random_ready_list_lock, flags); |
| 610 | } |
| 611 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 612 | /* |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 613 | * Credit (or debit) the entropy store with n bits of entropy. |
| 614 | * Use credit_entropy_bits_safe() if the value comes from userspace |
| 615 | * or otherwise should be checked for extreme values. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 616 | */ |
Matt Mackall | adc782d | 2008-04-29 01:03:07 -0700 | [diff] [blame] | 617 | static void credit_entropy_bits(struct entropy_store *r, int nbits) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 618 | { |
Theodore Ts'o | 902c098 | 2012-07-04 10:38:30 -0400 | [diff] [blame] | 619 | int entropy_count, orig; |
H. Peter Anvin | 30e37ec | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 620 | const int pool_size = r->poolinfo->poolfracbits; |
| 621 | int nfrac = nbits << ENTROPY_SHIFT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 622 | |
Matt Mackall | adc782d | 2008-04-29 01:03:07 -0700 | [diff] [blame] | 623 | if (!nbits) |
| 624 | return; |
| 625 | |
Theodore Ts'o | 902c098 | 2012-07-04 10:38:30 -0400 | [diff] [blame] | 626 | retry: |
| 627 | entropy_count = orig = ACCESS_ONCE(r->entropy_count); |
H. Peter Anvin | 30e37ec | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 628 | if (nfrac < 0) { |
| 629 | /* Debit */ |
| 630 | entropy_count += nfrac; |
| 631 | } else { |
| 632 | /* |
| 633 | * Credit: we have to account for the possibility of |
| 634 | * overwriting already present entropy. Even in the |
| 635 | * ideal case of pure Shannon entropy, new contributions |
| 636 | * approach the full value asymptotically: |
| 637 | * |
| 638 | * entropy <- entropy + (pool_size - entropy) * |
| 639 | * (1 - exp(-add_entropy/pool_size)) |
| 640 | * |
| 641 | * For add_entropy <= pool_size/2 then |
| 642 | * (1 - exp(-add_entropy/pool_size)) >= |
| 643 | * (add_entropy/pool_size)*0.7869... |
| 644 | * so we can approximate the exponential with |
| 645 | * 3/4*add_entropy/pool_size and still be on the |
| 646 | * safe side by adding at most pool_size/2 at a time. |
| 647 | * |
| 648 | * The use of pool_size-2 in the while statement is to |
| 649 | * prevent rounding artifacts from making the loop |
| 650 | * arbitrarily long; this limits the loop to log2(pool_size)*2 |
| 651 | * turns no matter how large nbits is. |
| 652 | */ |
| 653 | int pnfrac = nfrac; |
| 654 | const int s = r->poolinfo->poolbitshift + ENTROPY_SHIFT + 2; |
| 655 | /* The +2 corresponds to the /4 in the denominator */ |
| 656 | |
| 657 | do { |
| 658 | unsigned int anfrac = min(pnfrac, pool_size/2); |
| 659 | unsigned int add = |
| 660 | ((pool_size - entropy_count)*anfrac*3) >> s; |
| 661 | |
| 662 | entropy_count += add; |
| 663 | pnfrac -= anfrac; |
| 664 | } while (unlikely(entropy_count < pool_size-2 && pnfrac)); |
| 665 | } |
Theodore Ts'o | 00ce1db | 2012-07-04 16:19:30 -0400 | [diff] [blame] | 666 | |
Hannes Frederic Sowa | 79a8468 | 2014-07-18 17:26:41 -0400 | [diff] [blame] | 667 | if (unlikely(entropy_count < 0)) { |
Theodore Ts'o | f80bbd8 | 2013-10-03 12:02:37 -0400 | [diff] [blame] | 668 | pr_warn("random: negative entropy/overflow: pool %s count %d\n", |
| 669 | r->name, entropy_count); |
| 670 | WARN_ON(1); |
Andrew Morton | 8b76f46 | 2008-09-02 14:36:14 -0700 | [diff] [blame] | 671 | entropy_count = 0; |
H. Peter Anvin | 30e37ec | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 672 | } else if (entropy_count > pool_size) |
| 673 | entropy_count = pool_size; |
Theodore Ts'o | 902c098 | 2012-07-04 10:38:30 -0400 | [diff] [blame] | 674 | if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) |
| 675 | goto retry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 676 | |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 677 | r->entropy_total += nbits; |
Linus Torvalds | 0891ad8 | 2013-11-16 10:19:15 -0800 | [diff] [blame] | 678 | if (!r->initialized && r->entropy_total > 128) { |
| 679 | r->initialized = 1; |
| 680 | r->entropy_total = 0; |
| 681 | if (r == &nonblocking_pool) { |
| 682 | prandom_reseed_late(); |
Herbert Xu | 205a525 | 2015-06-09 18:19:39 +0800 | [diff] [blame] | 683 | process_random_ready_list(); |
Herbert Xu | 1d9de44 | 2015-05-21 16:19:54 +0800 | [diff] [blame] | 684 | wake_up_all(&urandom_init_wait); |
Linus Torvalds | 0891ad8 | 2013-11-16 10:19:15 -0800 | [diff] [blame] | 685 | pr_notice("random: %s pool is initialized\n", r->name); |
Hannes Frederic Sowa | 4af712e | 2013-11-11 12:20:34 +0100 | [diff] [blame] | 686 | } |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 687 | } |
| 688 | |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 689 | trace_credit_entropy_bits(r->name, nbits, |
| 690 | entropy_count >> ENTROPY_SHIFT, |
Theodore Ts'o | 00ce1db | 2012-07-04 16:19:30 -0400 | [diff] [blame] | 691 | r->entropy_total, _RET_IP_); |
| 692 | |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 693 | if (r == &input_pool) { |
Greg Price | 7d1b08c | 2013-12-07 09:49:55 -0500 | [diff] [blame] | 694 | int entropy_bits = entropy_count >> ENTROPY_SHIFT; |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 695 | |
| 696 | /* should we wake readers? */ |
Greg Price | 2132a96 | 2013-12-06 21:28:03 -0500 | [diff] [blame] | 697 | if (entropy_bits >= random_read_wakeup_bits) { |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 698 | wake_up_interruptible(&random_read_wait); |
| 699 | kill_fasync(&fasync, SIGIO, POLL_IN); |
| 700 | } |
| 701 | /* If the input pool is getting full, send some |
| 702 | * entropy to the two output pools, flipping back and |
| 703 | * forth between them, until the output pools are 75% |
| 704 | * full. |
| 705 | */ |
Greg Price | 2132a96 | 2013-12-06 21:28:03 -0500 | [diff] [blame] | 706 | if (entropy_bits > random_write_wakeup_bits && |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 707 | r->initialized && |
Greg Price | 2132a96 | 2013-12-06 21:28:03 -0500 | [diff] [blame] | 708 | r->entropy_total >= 2*random_read_wakeup_bits) { |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 709 | static struct entropy_store *last = &blocking_pool; |
| 710 | struct entropy_store *other = &blocking_pool; |
| 711 | |
| 712 | if (last == &blocking_pool) |
| 713 | other = &nonblocking_pool; |
| 714 | if (other->entropy_count <= |
| 715 | 3 * other->poolinfo->poolfracbits / 4) |
| 716 | last = other; |
| 717 | if (last->entropy_count <= |
| 718 | 3 * last->poolinfo->poolfracbits / 4) { |
| 719 | schedule_work(&last->push_work); |
| 720 | r->entropy_total = 0; |
| 721 | } |
| 722 | } |
Jeff Dike | 9a6f70b | 2008-04-29 01:03:08 -0700 | [diff] [blame] | 723 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 724 | } |
| 725 | |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 726 | static void credit_entropy_bits_safe(struct entropy_store *r, int nbits) |
| 727 | { |
| 728 | const int nbits_max = (int)(~0U >> (ENTROPY_SHIFT + 1)); |
| 729 | |
| 730 | /* Cap the value to avoid overflows */ |
| 731 | nbits = min(nbits, nbits_max); |
| 732 | nbits = max(nbits, -nbits_max); |
| 733 | |
| 734 | credit_entropy_bits(r, nbits); |
| 735 | } |
| 736 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 737 | /********************************************************************* |
| 738 | * |
| 739 | * Entropy input management |
| 740 | * |
| 741 | *********************************************************************/ |
| 742 | |
| 743 | /* There is one of these per entropy source */ |
| 744 | struct timer_rand_state { |
| 745 | cycles_t last_time; |
Matt Mackall | 90b75ee | 2008-04-29 01:02:55 -0700 | [diff] [blame] | 746 | long last_delta, last_delta2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 747 | unsigned dont_count_entropy:1; |
| 748 | }; |
| 749 | |
Theodore Ts'o | 644008d | 2013-11-03 16:40:53 -0500 | [diff] [blame] | 750 | #define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, }; |
| 751 | |
Linus Torvalds | a2080a6 | 2012-07-04 11:16:01 -0400 | [diff] [blame] | 752 | /* |
| 753 | * Add device- or boot-specific data to the input and nonblocking |
| 754 | * pools to help initialize them to unique values. |
| 755 | * |
| 756 | * None of this adds any entropy, it is meant to avoid the |
| 757 | * problem of the nonblocking pool having similar initial state |
| 758 | * across largely identical devices. |
| 759 | */ |
| 760 | void add_device_randomness(const void *buf, unsigned int size) |
| 761 | { |
Theodore Ts'o | 61875f3 | 2013-09-21 13:58:22 -0400 | [diff] [blame] | 762 | unsigned long time = random_get_entropy() ^ jiffies; |
Theodore Ts'o | 3ef4cb2 | 2013-09-12 14:27:22 -0400 | [diff] [blame] | 763 | unsigned long flags; |
Linus Torvalds | a2080a6 | 2012-07-04 11:16:01 -0400 | [diff] [blame] | 764 | |
Theodore Ts'o | 5910895 | 2013-09-12 14:10:25 -0400 | [diff] [blame] | 765 | trace_add_device_randomness(size, _RET_IP_); |
Theodore Ts'o | 3ef4cb2 | 2013-09-12 14:27:22 -0400 | [diff] [blame] | 766 | spin_lock_irqsave(&input_pool.lock, flags); |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 767 | _mix_pool_bytes(&input_pool, buf, size); |
| 768 | _mix_pool_bytes(&input_pool, &time, sizeof(time)); |
Theodore Ts'o | 3ef4cb2 | 2013-09-12 14:27:22 -0400 | [diff] [blame] | 769 | spin_unlock_irqrestore(&input_pool.lock, flags); |
| 770 | |
| 771 | spin_lock_irqsave(&nonblocking_pool.lock, flags); |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 772 | _mix_pool_bytes(&nonblocking_pool, buf, size); |
| 773 | _mix_pool_bytes(&nonblocking_pool, &time, sizeof(time)); |
Theodore Ts'o | 3ef4cb2 | 2013-09-12 14:27:22 -0400 | [diff] [blame] | 774 | spin_unlock_irqrestore(&nonblocking_pool.lock, flags); |
Linus Torvalds | a2080a6 | 2012-07-04 11:16:01 -0400 | [diff] [blame] | 775 | } |
| 776 | EXPORT_SYMBOL(add_device_randomness); |
| 777 | |
Theodore Ts'o | 644008d | 2013-11-03 16:40:53 -0500 | [diff] [blame] | 778 | static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE; |
Yinghai Lu | 3060d6f | 2008-08-19 20:50:08 -0700 | [diff] [blame] | 779 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 780 | /* |
| 781 | * This function adds entropy to the entropy "pool" by using timing |
| 782 | * delays. It uses the timer_rand_state structure to make an estimate |
| 783 | * of how many bits of entropy this call has added to the pool. |
| 784 | * |
| 785 | * The number "num" is also added to the pool - it should somehow describe |
| 786 | * the type of event which just happened. This is currently 0-255 for |
| 787 | * keyboard scan codes, and 256 upwards for interrupts. |
| 788 | * |
| 789 | */ |
| 790 | static void add_timer_randomness(struct timer_rand_state *state, unsigned num) |
| 791 | { |
Theodore Ts'o | 40db23e | 2013-11-03 00:15:05 -0400 | [diff] [blame] | 792 | struct entropy_store *r; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 793 | struct { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 794 | long jiffies; |
Linus Torvalds | cf833d0 | 2011-12-22 11:36:22 -0800 | [diff] [blame] | 795 | unsigned cycles; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 796 | unsigned num; |
| 797 | } sample; |
| 798 | long delta, delta2, delta3; |
| 799 | |
| 800 | preempt_disable(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 801 | |
| 802 | sample.jiffies = jiffies; |
Theodore Ts'o | 61875f3 | 2013-09-21 13:58:22 -0400 | [diff] [blame] | 803 | sample.cycles = random_get_entropy(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 804 | sample.num = num; |
Theodore Ts'o | 40db23e | 2013-11-03 00:15:05 -0400 | [diff] [blame] | 805 | r = nonblocking_pool.initialized ? &input_pool : &nonblocking_pool; |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 806 | mix_pool_bytes(r, &sample, sizeof(sample)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 807 | |
| 808 | /* |
| 809 | * Calculate number of bits of randomness we probably added. |
| 810 | * We take into account the first, second and third-order deltas |
| 811 | * in order to make our estimate. |
| 812 | */ |
| 813 | |
| 814 | if (!state->dont_count_entropy) { |
| 815 | delta = sample.jiffies - state->last_time; |
| 816 | state->last_time = sample.jiffies; |
| 817 | |
| 818 | delta2 = delta - state->last_delta; |
| 819 | state->last_delta = delta; |
| 820 | |
| 821 | delta3 = delta2 - state->last_delta2; |
| 822 | state->last_delta2 = delta2; |
| 823 | |
| 824 | if (delta < 0) |
| 825 | delta = -delta; |
| 826 | if (delta2 < 0) |
| 827 | delta2 = -delta2; |
| 828 | if (delta3 < 0) |
| 829 | delta3 = -delta3; |
| 830 | if (delta > delta2) |
| 831 | delta = delta2; |
| 832 | if (delta > delta3) |
| 833 | delta = delta3; |
| 834 | |
| 835 | /* |
| 836 | * delta is now minimum absolute delta. |
| 837 | * Round down by 1 bit on general principles, |
| 838 | * and limit entropy entimate to 12 bits. |
| 839 | */ |
Theodore Ts'o | 40db23e | 2013-11-03 00:15:05 -0400 | [diff] [blame] | 840 | credit_entropy_bits(r, min_t(int, fls(delta>>1), 11)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 841 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 842 | preempt_enable(); |
| 843 | } |
| 844 | |
Stephen Hemminger | d251575 | 2006-01-11 12:17:38 -0800 | [diff] [blame] | 845 | void add_input_randomness(unsigned int type, unsigned int code, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 846 | unsigned int value) |
| 847 | { |
| 848 | static unsigned char last_value; |
| 849 | |
| 850 | /* ignore autorepeat and the like */ |
| 851 | if (value == last_value) |
| 852 | return; |
| 853 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 854 | last_value = value; |
| 855 | add_timer_randomness(&input_timer_state, |
| 856 | (type << 4) ^ code ^ (code >> 4) ^ value); |
Theodore Ts'o | f80bbd8 | 2013-10-03 12:02:37 -0400 | [diff] [blame] | 857 | trace_add_input_randomness(ENTROPY_BITS(&input_pool)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 858 | } |
Dmitry Torokhov | 80fc9f5 | 2006-10-11 01:43:58 -0400 | [diff] [blame] | 859 | EXPORT_SYMBOL_GPL(add_input_randomness); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 860 | |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 861 | static DEFINE_PER_CPU(struct fast_pool, irq_randomness); |
| 862 | |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 863 | #ifdef ADD_INTERRUPT_BENCH |
| 864 | static unsigned long avg_cycles, avg_deviation; |
| 865 | |
| 866 | #define AVG_SHIFT 8 /* Exponential average factor k=1/256 */ |
| 867 | #define FIXED_1_2 (1 << (AVG_SHIFT-1)) |
| 868 | |
| 869 | static void add_interrupt_bench(cycles_t start) |
| 870 | { |
| 871 | long delta = random_get_entropy() - start; |
| 872 | |
| 873 | /* Use a weighted moving average */ |
| 874 | delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT); |
| 875 | avg_cycles += delta; |
| 876 | /* And average deviation */ |
| 877 | delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT); |
| 878 | avg_deviation += delta; |
| 879 | } |
| 880 | #else |
| 881 | #define add_interrupt_bench(x) |
| 882 | #endif |
| 883 | |
Theodore Ts'o | ee3e00e | 2014-06-15 16:59:24 -0400 | [diff] [blame] | 884 | static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs) |
| 885 | { |
| 886 | __u32 *ptr = (__u32 *) regs; |
| 887 | |
| 888 | if (regs == NULL) |
| 889 | return 0; |
| 890 | if (f->reg_idx >= sizeof(struct pt_regs) / sizeof(__u32)) |
| 891 | f->reg_idx = 0; |
| 892 | return *(ptr + f->reg_idx++); |
| 893 | } |
| 894 | |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 895 | void add_interrupt_randomness(int irq, int irq_flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 896 | { |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 897 | struct entropy_store *r; |
Christoph Lameter | 1b2a1a7 | 2014-08-17 12:30:29 -0500 | [diff] [blame] | 898 | struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness); |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 899 | struct pt_regs *regs = get_irq_regs(); |
| 900 | unsigned long now = jiffies; |
Theodore Ts'o | 655b226 | 2013-09-22 15:24:02 -0400 | [diff] [blame] | 901 | cycles_t cycles = random_get_entropy(); |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 902 | __u32 c_high, j_high; |
Theodore Ts'o | 655b226 | 2013-09-22 15:24:02 -0400 | [diff] [blame] | 903 | __u64 ip; |
H. Peter Anvin | 83664a6 | 2014-03-17 16:36:28 -0700 | [diff] [blame] | 904 | unsigned long seed; |
Theodore Ts'o | 91fcb53 | 2014-06-10 22:46:37 -0400 | [diff] [blame] | 905 | int credit = 0; |
Yinghai Lu | 3060d6f | 2008-08-19 20:50:08 -0700 | [diff] [blame] | 906 | |
Theodore Ts'o | ee3e00e | 2014-06-15 16:59:24 -0400 | [diff] [blame] | 907 | if (cycles == 0) |
| 908 | cycles = get_reg(fast_pool, regs); |
Theodore Ts'o | 655b226 | 2013-09-22 15:24:02 -0400 | [diff] [blame] | 909 | c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0; |
| 910 | j_high = (sizeof(now) > 4) ? now >> 32 : 0; |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 911 | fast_pool->pool[0] ^= cycles ^ j_high ^ irq; |
| 912 | fast_pool->pool[1] ^= now ^ c_high; |
Theodore Ts'o | 655b226 | 2013-09-22 15:24:02 -0400 | [diff] [blame] | 913 | ip = regs ? instruction_pointer(regs) : _RET_IP_; |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 914 | fast_pool->pool[2] ^= ip; |
Theodore Ts'o | ee3e00e | 2014-06-15 16:59:24 -0400 | [diff] [blame] | 915 | fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 : |
| 916 | get_reg(fast_pool, regs); |
Yinghai Lu | 3060d6f | 2008-08-19 20:50:08 -0700 | [diff] [blame] | 917 | |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 918 | fast_mix(fast_pool); |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 919 | add_interrupt_bench(cycles); |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 920 | |
Theodore Ts'o | ee3e00e | 2014-06-15 16:59:24 -0400 | [diff] [blame] | 921 | if ((fast_pool->count < 64) && |
| 922 | !time_after(now, fast_pool->last + HZ)) |
| 923 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 924 | |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 925 | r = nonblocking_pool.initialized ? &input_pool : &nonblocking_pool; |
Theodore Ts'o | 840f950 | 2014-06-14 03:06:57 -0400 | [diff] [blame] | 926 | if (!spin_trylock(&r->lock)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 927 | return; |
| 928 | |
Theodore Ts'o | 775f4b2 | 2012-07-02 07:52:16 -0400 | [diff] [blame] | 929 | fast_pool->last = now; |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 930 | __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool)); |
H. Peter Anvin | 83664a6 | 2014-03-17 16:36:28 -0700 | [diff] [blame] | 931 | |
| 932 | /* |
| 933 | * If we have architectural seed generator, produce a seed and |
Theodore Ts'o | 48d6be9 | 2014-07-17 05:27:30 -0400 | [diff] [blame] | 934 | * add it to the pool. For the sake of paranoia don't let the |
| 935 | * architectural seed generator dominate the input from the |
| 936 | * interrupt noise. |
H. Peter Anvin | 83664a6 | 2014-03-17 16:36:28 -0700 | [diff] [blame] | 937 | */ |
| 938 | if (arch_get_random_seed_long(&seed)) { |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 939 | __mix_pool_bytes(r, &seed, sizeof(seed)); |
Theodore Ts'o | 48d6be9 | 2014-07-17 05:27:30 -0400 | [diff] [blame] | 940 | credit = 1; |
H. Peter Anvin | 83664a6 | 2014-03-17 16:36:28 -0700 | [diff] [blame] | 941 | } |
Theodore Ts'o | 91fcb53 | 2014-06-10 22:46:37 -0400 | [diff] [blame] | 942 | spin_unlock(&r->lock); |
H. Peter Anvin | 83664a6 | 2014-03-17 16:36:28 -0700 | [diff] [blame] | 943 | |
Theodore Ts'o | ee3e00e | 2014-06-15 16:59:24 -0400 | [diff] [blame] | 944 | fast_pool->count = 0; |
Theodore Ts'o | 840f950 | 2014-06-14 03:06:57 -0400 | [diff] [blame] | 945 | |
Theodore Ts'o | ee3e00e | 2014-06-15 16:59:24 -0400 | [diff] [blame] | 946 | /* award one bit for the contents of the fast pool */ |
| 947 | credit_entropy_bits(r, credit + 1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 948 | } |
| 949 | |
David Howells | 9361401 | 2006-09-30 20:45:40 +0200 | [diff] [blame] | 950 | #ifdef CONFIG_BLOCK |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 951 | void add_disk_randomness(struct gendisk *disk) |
| 952 | { |
| 953 | if (!disk || !disk->random) |
| 954 | return; |
| 955 | /* first major is 1, so we get >= 0x200 here */ |
Tejun Heo | f331c02 | 2008-09-03 09:01:48 +0200 | [diff] [blame] | 956 | add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); |
Theodore Ts'o | f80bbd8 | 2013-10-03 12:02:37 -0400 | [diff] [blame] | 957 | trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS(&input_pool)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 958 | } |
Christoph Hellwig | bdcfa3e | 2014-04-25 00:36:37 -0700 | [diff] [blame] | 959 | EXPORT_SYMBOL_GPL(add_disk_randomness); |
David Howells | 9361401 | 2006-09-30 20:45:40 +0200 | [diff] [blame] | 960 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 961 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 962 | /********************************************************************* |
| 963 | * |
| 964 | * Entropy extraction routines |
| 965 | * |
| 966 | *********************************************************************/ |
| 967 | |
Matt Mackall | 90b75ee | 2008-04-29 01:02:55 -0700 | [diff] [blame] | 968 | static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 969 | size_t nbytes, int min, int rsvd); |
| 970 | |
| 971 | /* |
Lucas De Marchi | 25985ed | 2011-03-30 22:57:33 -0300 | [diff] [blame] | 972 | * This utility inline function is responsible for transferring entropy |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 973 | * from the primary pool to the secondary extraction pool. We make |
| 974 | * sure we pull enough for a 'catastrophic reseed'. |
| 975 | */ |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 976 | static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 977 | static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes) |
| 978 | { |
Theodore Ts'o | cff8503 | 2014-06-10 23:18:16 -0400 | [diff] [blame] | 979 | if (!r->pull || |
| 980 | r->entropy_count >= (nbytes << (ENTROPY_SHIFT + 3)) || |
| 981 | r->entropy_count > r->poolinfo->poolfracbits) |
| 982 | return; |
| 983 | |
Theodore Ts'o | f5c2742 | 2013-09-22 15:14:32 -0400 | [diff] [blame] | 984 | if (r->limit == 0 && random_min_urandom_seed) { |
| 985 | unsigned long now = jiffies; |
| 986 | |
| 987 | if (time_before(now, |
| 988 | r->last_pulled + random_min_urandom_seed * HZ)) |
| 989 | return; |
| 990 | r->last_pulled = now; |
| 991 | } |
Theodore Ts'o | cff8503 | 2014-06-10 23:18:16 -0400 | [diff] [blame] | 992 | |
| 993 | _xfer_secondary_pool(r, nbytes); |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 994 | } |
Matt Mackall | 5a021e9 | 2007-07-19 11:30:14 -0700 | [diff] [blame] | 995 | |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 996 | static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes) |
| 997 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 998 | __u32 tmp[OUTPUT_POOL_WORDS]; |
| 999 | |
Greg Price | 2132a96 | 2013-12-06 21:28:03 -0500 | [diff] [blame] | 1000 | /* For /dev/random's pool, always leave two wakeups' worth */ |
| 1001 | int rsvd_bytes = r->limit ? 0 : random_read_wakeup_bits / 4; |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 1002 | int bytes = nbytes; |
Matt Mackall | 5a021e9 | 2007-07-19 11:30:14 -0700 | [diff] [blame] | 1003 | |
Greg Price | 2132a96 | 2013-12-06 21:28:03 -0500 | [diff] [blame] | 1004 | /* pull at least as much as a wakeup */ |
| 1005 | bytes = max_t(int, bytes, random_read_wakeup_bits / 8); |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 1006 | /* but never more than the buffer size */ |
| 1007 | bytes = min_t(int, bytes, sizeof(tmp)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1008 | |
Theodore Ts'o | f80bbd8 | 2013-10-03 12:02:37 -0400 | [diff] [blame] | 1009 | trace_xfer_secondary_pool(r->name, bytes * 8, nbytes * 8, |
| 1010 | ENTROPY_BITS(r), ENTROPY_BITS(r->pull)); |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 1011 | bytes = extract_entropy(r->pull, tmp, bytes, |
Greg Price | 2132a96 | 2013-12-06 21:28:03 -0500 | [diff] [blame] | 1012 | random_read_wakeup_bits / 8, rsvd_bytes); |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 1013 | mix_pool_bytes(r, tmp, bytes); |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 1014 | credit_entropy_bits(r, bytes*8); |
| 1015 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1016 | |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 1017 | /* |
| 1018 | * Used as a workqueue function so that when the input pool is getting |
| 1019 | * full, we can "spill over" some entropy to the output pools. That |
| 1020 | * way the output pools can store some of the excess entropy instead |
| 1021 | * of letting it go to waste. |
| 1022 | */ |
| 1023 | static void push_to_pool(struct work_struct *work) |
| 1024 | { |
| 1025 | struct entropy_store *r = container_of(work, struct entropy_store, |
| 1026 | push_work); |
| 1027 | BUG_ON(!r); |
Greg Price | 2132a96 | 2013-12-06 21:28:03 -0500 | [diff] [blame] | 1028 | _xfer_secondary_pool(r, random_read_wakeup_bits/8); |
Theodore Ts'o | 6265e16 | 2013-10-03 01:08:15 -0400 | [diff] [blame] | 1029 | trace_push_to_pool(r->name, r->entropy_count >> ENTROPY_SHIFT, |
| 1030 | r->pull->entropy_count >> ENTROPY_SHIFT); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1031 | } |
| 1032 | |
| 1033 | /* |
Greg Price | 19fa5be | 2013-11-29 15:50:06 -0500 | [diff] [blame] | 1034 | * This function decides how many bytes to actually take from the |
| 1035 | * given pool, and also debits the entropy count accordingly. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1036 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1037 | static size_t account(struct entropy_store *r, size_t nbytes, int min, |
| 1038 | int reserved) |
| 1039 | { |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1040 | int entropy_count, orig; |
Hannes Frederic Sowa | 79a8468 | 2014-07-18 17:26:41 -0400 | [diff] [blame] | 1041 | size_t ibytes, nfrac; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1042 | |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1043 | BUG_ON(r->entropy_count > r->poolinfo->poolfracbits); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1044 | |
| 1045 | /* Can we pull enough? */ |
Jiri Kosina | 10b3a32 | 2013-05-24 15:55:33 -0700 | [diff] [blame] | 1046 | retry: |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1047 | entropy_count = orig = ACCESS_ONCE(r->entropy_count); |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1048 | ibytes = nbytes; |
Greg Price | 0fb7a01 | 2013-12-05 19:32:19 -0500 | [diff] [blame] | 1049 | /* If limited, never pull more than available */ |
Theodore Ts'o | e33ba5f | 2014-06-15 21:04:32 -0400 | [diff] [blame] | 1050 | if (r->limit) { |
| 1051 | int have_bytes = entropy_count >> (ENTROPY_SHIFT + 3); |
| 1052 | |
| 1053 | if ((have_bytes -= reserved) < 0) |
| 1054 | have_bytes = 0; |
| 1055 | ibytes = min_t(size_t, ibytes, have_bytes); |
| 1056 | } |
Greg Price | 0fb7a01 | 2013-12-05 19:32:19 -0500 | [diff] [blame] | 1057 | if (ibytes < min) |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1058 | ibytes = 0; |
Hannes Frederic Sowa | 79a8468 | 2014-07-18 17:26:41 -0400 | [diff] [blame] | 1059 | |
| 1060 | if (unlikely(entropy_count < 0)) { |
| 1061 | pr_warn("random: negative entropy count: pool %s count %d\n", |
| 1062 | r->name, entropy_count); |
| 1063 | WARN_ON(1); |
| 1064 | entropy_count = 0; |
| 1065 | } |
| 1066 | nfrac = ibytes << (ENTROPY_SHIFT + 3); |
| 1067 | if ((size_t) entropy_count > nfrac) |
| 1068 | entropy_count -= nfrac; |
| 1069 | else |
Theodore Ts'o | e33ba5f | 2014-06-15 21:04:32 -0400 | [diff] [blame] | 1070 | entropy_count = 0; |
Theodore Ts'o | f9c6d49 | 2014-05-16 21:40:41 -0400 | [diff] [blame] | 1071 | |
Greg Price | 0fb7a01 | 2013-12-05 19:32:19 -0500 | [diff] [blame] | 1072 | if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) |
| 1073 | goto retry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1074 | |
Theodore Ts'o | f80bbd8 | 2013-10-03 12:02:37 -0400 | [diff] [blame] | 1075 | trace_debit_entropy(r->name, 8 * ibytes); |
Greg Price | 0fb7a01 | 2013-12-05 19:32:19 -0500 | [diff] [blame] | 1076 | if (ibytes && |
Greg Price | 2132a96 | 2013-12-06 21:28:03 -0500 | [diff] [blame] | 1077 | (r->entropy_count >> ENTROPY_SHIFT) < random_write_wakeup_bits) { |
Theodore Ts'o | b980955 | 2013-03-04 11:59:12 -0500 | [diff] [blame] | 1078 | wake_up_interruptible(&random_write_wait); |
| 1079 | kill_fasync(&fasync, SIGIO, POLL_OUT); |
| 1080 | } |
| 1081 | |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1082 | return ibytes; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1083 | } |
| 1084 | |
Greg Price | 19fa5be | 2013-11-29 15:50:06 -0500 | [diff] [blame] | 1085 | /* |
| 1086 | * This function does the actual extraction for extract_entropy and |
| 1087 | * extract_entropy_user. |
| 1088 | * |
| 1089 | * Note: we assume that .poolwords is a multiple of 16 words. |
| 1090 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1091 | static void extract_buf(struct entropy_store *r, __u8 *out) |
| 1092 | { |
Matt Mackall | 602b6ae | 2007-05-29 21:54:27 -0500 | [diff] [blame] | 1093 | int i; |
H. Peter Anvin | d2e7c96 | 2012-07-27 22:26:08 -0400 | [diff] [blame] | 1094 | union { |
| 1095 | __u32 w[5]; |
Theodore Ts'o | 85a1f77 | 2013-09-21 18:06:02 -0400 | [diff] [blame] | 1096 | unsigned long l[LONGS(20)]; |
H. Peter Anvin | d2e7c96 | 2012-07-27 22:26:08 -0400 | [diff] [blame] | 1097 | } hash; |
| 1098 | __u32 workspace[SHA_WORKSPACE_WORDS]; |
Theodore Ts'o | 902c098 | 2012-07-04 10:38:30 -0400 | [diff] [blame] | 1099 | unsigned long flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1100 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1101 | /* |
Greg Price | dfd3875 | 2013-11-29 14:58:06 -0500 | [diff] [blame] | 1102 | * If we have an architectural hardware random number |
Theodore Ts'o | 4688444 | 2013-12-17 21:16:39 -0500 | [diff] [blame] | 1103 | * generator, use it for SHA's initial vector |
Theodore Ts'o | 85a1f77 | 2013-09-21 18:06:02 -0400 | [diff] [blame] | 1104 | */ |
Theodore Ts'o | 4688444 | 2013-12-17 21:16:39 -0500 | [diff] [blame] | 1105 | sha_init(hash.w); |
Theodore Ts'o | 85a1f77 | 2013-09-21 18:06:02 -0400 | [diff] [blame] | 1106 | for (i = 0; i < LONGS(20); i++) { |
| 1107 | unsigned long v; |
| 1108 | if (!arch_get_random_long(&v)) |
| 1109 | break; |
Theodore Ts'o | 4688444 | 2013-12-17 21:16:39 -0500 | [diff] [blame] | 1110 | hash.l[i] = v; |
Theodore Ts'o | 85a1f77 | 2013-09-21 18:06:02 -0400 | [diff] [blame] | 1111 | } |
| 1112 | |
Theodore Ts'o | 4688444 | 2013-12-17 21:16:39 -0500 | [diff] [blame] | 1113 | /* Generate a hash across the pool, 16 words (512 bits) at a time */ |
| 1114 | spin_lock_irqsave(&r->lock, flags); |
| 1115 | for (i = 0; i < r->poolinfo->poolwords; i += 16) |
| 1116 | sha_transform(hash.w, (__u8 *)(r->pool + i), workspace); |
| 1117 | |
Theodore Ts'o | 85a1f77 | 2013-09-21 18:06:02 -0400 | [diff] [blame] | 1118 | /* |
Matt Mackall | 1c0ad3d | 2008-04-29 01:03:00 -0700 | [diff] [blame] | 1119 | * We mix the hash back into the pool to prevent backtracking |
| 1120 | * attacks (where the attacker knows the state of the pool |
| 1121 | * plus the current outputs, and attempts to find previous |
| 1122 | * ouputs), unless the hash function can be inverted. By |
| 1123 | * mixing at least a SHA1 worth of hash data back, we make |
| 1124 | * brute-forcing the feedback as hard as brute-forcing the |
| 1125 | * hash. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1126 | */ |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 1127 | __mix_pool_bytes(r, hash.w, sizeof(hash.w)); |
Theodore Ts'o | 902c098 | 2012-07-04 10:38:30 -0400 | [diff] [blame] | 1128 | spin_unlock_irqrestore(&r->lock, flags); |
Matt Mackall | 1c0ad3d | 2008-04-29 01:03:00 -0700 | [diff] [blame] | 1129 | |
Daniel Borkmann | d4c5efd | 2014-08-26 23:16:35 -0400 | [diff] [blame] | 1130 | memzero_explicit(workspace, sizeof(workspace)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1131 | |
| 1132 | /* |
Matt Mackall | 1c0ad3d | 2008-04-29 01:03:00 -0700 | [diff] [blame] | 1133 | * In case the hash function has some recognizable output |
| 1134 | * pattern, we fold it in half. Thus, we always feed back |
| 1135 | * twice as much data as we output. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1136 | */ |
H. Peter Anvin | d2e7c96 | 2012-07-27 22:26:08 -0400 | [diff] [blame] | 1137 | hash.w[0] ^= hash.w[3]; |
| 1138 | hash.w[1] ^= hash.w[4]; |
| 1139 | hash.w[2] ^= rol32(hash.w[2], 16); |
| 1140 | |
H. Peter Anvin | d2e7c96 | 2012-07-27 22:26:08 -0400 | [diff] [blame] | 1141 | memcpy(out, &hash, EXTRACT_SIZE); |
Daniel Borkmann | d4c5efd | 2014-08-26 23:16:35 -0400 | [diff] [blame] | 1142 | memzero_explicit(&hash, sizeof(hash)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1143 | } |
| 1144 | |
Greg Price | 19fa5be | 2013-11-29 15:50:06 -0500 | [diff] [blame] | 1145 | /* |
| 1146 | * This function extracts randomness from the "entropy pool", and |
| 1147 | * returns it in a buffer. |
| 1148 | * |
| 1149 | * The min parameter specifies the minimum amount we can pull before |
| 1150 | * failing to avoid races that defeat catastrophic reseeding while the |
| 1151 | * reserved parameter indicates how much entropy we must leave in the |
| 1152 | * pool after each pull to avoid starving other readers. |
| 1153 | */ |
Matt Mackall | 90b75ee | 2008-04-29 01:02:55 -0700 | [diff] [blame] | 1154 | static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
Theodore Ts'o | 902c098 | 2012-07-04 10:38:30 -0400 | [diff] [blame] | 1155 | size_t nbytes, int min, int reserved) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1156 | { |
| 1157 | ssize_t ret = 0, i; |
| 1158 | __u8 tmp[EXTRACT_SIZE]; |
Jarod Wilson | 1e7e2e0 | 2013-05-24 15:55:31 -0700 | [diff] [blame] | 1159 | unsigned long flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1160 | |
Jarod Wilson | ec8f02da | 2012-11-06 10:42:42 -0500 | [diff] [blame] | 1161 | /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */ |
Jarod Wilson | 1e7e2e0 | 2013-05-24 15:55:31 -0700 | [diff] [blame] | 1162 | if (fips_enabled) { |
| 1163 | spin_lock_irqsave(&r->lock, flags); |
| 1164 | if (!r->last_data_init) { |
Theodore Ts'o | c59974a | 2013-09-21 19:42:41 -0400 | [diff] [blame] | 1165 | r->last_data_init = 1; |
Jarod Wilson | 1e7e2e0 | 2013-05-24 15:55:31 -0700 | [diff] [blame] | 1166 | spin_unlock_irqrestore(&r->lock, flags); |
| 1167 | trace_extract_entropy(r->name, EXTRACT_SIZE, |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1168 | ENTROPY_BITS(r), _RET_IP_); |
Jarod Wilson | 1e7e2e0 | 2013-05-24 15:55:31 -0700 | [diff] [blame] | 1169 | xfer_secondary_pool(r, EXTRACT_SIZE); |
| 1170 | extract_buf(r, tmp); |
| 1171 | spin_lock_irqsave(&r->lock, flags); |
| 1172 | memcpy(r->last_data, tmp, EXTRACT_SIZE); |
| 1173 | } |
| 1174 | spin_unlock_irqrestore(&r->lock, flags); |
| 1175 | } |
Jarod Wilson | ec8f02da | 2012-11-06 10:42:42 -0500 | [diff] [blame] | 1176 | |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1177 | trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1178 | xfer_secondary_pool(r, nbytes); |
| 1179 | nbytes = account(r, nbytes, min, reserved); |
| 1180 | |
| 1181 | while (nbytes) { |
| 1182 | extract_buf(r, tmp); |
Neil Horman | 5b739ef | 2009-06-18 19:50:21 +0800 | [diff] [blame] | 1183 | |
Matt Mackall | e954bc9 | 2010-05-20 19:55:01 +1000 | [diff] [blame] | 1184 | if (fips_enabled) { |
Neil Horman | 5b739ef | 2009-06-18 19:50:21 +0800 | [diff] [blame] | 1185 | spin_lock_irqsave(&r->lock, flags); |
| 1186 | if (!memcmp(tmp, r->last_data, EXTRACT_SIZE)) |
| 1187 | panic("Hardware RNG duplicated output!\n"); |
| 1188 | memcpy(r->last_data, tmp, EXTRACT_SIZE); |
| 1189 | spin_unlock_irqrestore(&r->lock, flags); |
| 1190 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1191 | i = min_t(int, nbytes, EXTRACT_SIZE); |
| 1192 | memcpy(buf, tmp, i); |
| 1193 | nbytes -= i; |
| 1194 | buf += i; |
| 1195 | ret += i; |
| 1196 | } |
| 1197 | |
| 1198 | /* Wipe data just returned from memory */ |
Daniel Borkmann | d4c5efd | 2014-08-26 23:16:35 -0400 | [diff] [blame] | 1199 | memzero_explicit(tmp, sizeof(tmp)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1200 | |
| 1201 | return ret; |
| 1202 | } |
| 1203 | |
Greg Price | 19fa5be | 2013-11-29 15:50:06 -0500 | [diff] [blame] | 1204 | /* |
| 1205 | * This function extracts randomness from the "entropy pool", and |
| 1206 | * returns it in a userspace buffer. |
| 1207 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1208 | static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf, |
| 1209 | size_t nbytes) |
| 1210 | { |
| 1211 | ssize_t ret = 0, i; |
| 1212 | __u8 tmp[EXTRACT_SIZE]; |
Theodore Ts'o | c6e9d6f | 2014-07-17 04:13:05 -0400 | [diff] [blame] | 1213 | int large_request = (nbytes > 256); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1214 | |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1215 | trace_extract_entropy_user(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1216 | xfer_secondary_pool(r, nbytes); |
| 1217 | nbytes = account(r, nbytes, 0, 0); |
| 1218 | |
| 1219 | while (nbytes) { |
Theodore Ts'o | c6e9d6f | 2014-07-17 04:13:05 -0400 | [diff] [blame] | 1220 | if (large_request && need_resched()) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1221 | if (signal_pending(current)) { |
| 1222 | if (ret == 0) |
| 1223 | ret = -ERESTARTSYS; |
| 1224 | break; |
| 1225 | } |
| 1226 | schedule(); |
| 1227 | } |
| 1228 | |
| 1229 | extract_buf(r, tmp); |
| 1230 | i = min_t(int, nbytes, EXTRACT_SIZE); |
| 1231 | if (copy_to_user(buf, tmp, i)) { |
| 1232 | ret = -EFAULT; |
| 1233 | break; |
| 1234 | } |
| 1235 | |
| 1236 | nbytes -= i; |
| 1237 | buf += i; |
| 1238 | ret += i; |
| 1239 | } |
| 1240 | |
| 1241 | /* Wipe data just returned from memory */ |
Daniel Borkmann | d4c5efd | 2014-08-26 23:16:35 -0400 | [diff] [blame] | 1242 | memzero_explicit(tmp, sizeof(tmp)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1243 | |
| 1244 | return ret; |
| 1245 | } |
| 1246 | |
| 1247 | /* |
| 1248 | * This function is the exported kernel interface. It returns some |
Theodore Ts'o | c2557a3 | 2012-07-05 10:35:23 -0400 | [diff] [blame] | 1249 | * number of good random numbers, suitable for key generation, seeding |
Greg Price | 18e9cea | 2013-11-29 14:59:45 -0500 | [diff] [blame] | 1250 | * TCP sequence numbers, etc. It does not rely on the hardware random |
| 1251 | * number generator. For random bytes direct from the hardware RNG |
| 1252 | * (when available), use get_random_bytes_arch(). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1253 | */ |
| 1254 | void get_random_bytes(void *buf, int nbytes) |
| 1255 | { |
Theodore Ts'o | 392a546 | 2013-11-03 18:24:08 -0500 | [diff] [blame] | 1256 | #if DEBUG_RANDOM_BOOT > 0 |
| 1257 | if (unlikely(nonblocking_pool.initialized == 0)) |
| 1258 | printk(KERN_NOTICE "random: %pF get_random_bytes called " |
| 1259 | "with %d bits of entropy available\n", |
| 1260 | (void *) _RET_IP_, |
| 1261 | nonblocking_pool.entropy_total); |
| 1262 | #endif |
Theodore Ts'o | 5910895 | 2013-09-12 14:10:25 -0400 | [diff] [blame] | 1263 | trace_get_random_bytes(nbytes, _RET_IP_); |
Theodore Ts'o | c2557a3 | 2012-07-05 10:35:23 -0400 | [diff] [blame] | 1264 | extract_entropy(&nonblocking_pool, buf, nbytes, 0, 0); |
| 1265 | } |
| 1266 | EXPORT_SYMBOL(get_random_bytes); |
| 1267 | |
| 1268 | /* |
Herbert Xu | 205a525 | 2015-06-09 18:19:39 +0800 | [diff] [blame] | 1269 | * Add a callback function that will be invoked when the nonblocking |
| 1270 | * pool is initialised. |
| 1271 | * |
| 1272 | * returns: 0 if callback is successfully added |
| 1273 | * -EALREADY if pool is already initialised (callback not called) |
| 1274 | * -ENOENT if module for callback is not alive |
| 1275 | */ |
| 1276 | int add_random_ready_callback(struct random_ready_callback *rdy) |
| 1277 | { |
| 1278 | struct module *owner; |
| 1279 | unsigned long flags; |
| 1280 | int err = -EALREADY; |
| 1281 | |
| 1282 | if (likely(nonblocking_pool.initialized)) |
| 1283 | return err; |
| 1284 | |
| 1285 | owner = rdy->owner; |
| 1286 | if (!try_module_get(owner)) |
| 1287 | return -ENOENT; |
| 1288 | |
| 1289 | spin_lock_irqsave(&random_ready_list_lock, flags); |
| 1290 | if (nonblocking_pool.initialized) |
| 1291 | goto out; |
| 1292 | |
| 1293 | owner = NULL; |
| 1294 | |
| 1295 | list_add(&rdy->list, &random_ready_list); |
| 1296 | err = 0; |
| 1297 | |
| 1298 | out: |
| 1299 | spin_unlock_irqrestore(&random_ready_list_lock, flags); |
| 1300 | |
| 1301 | module_put(owner); |
| 1302 | |
| 1303 | return err; |
| 1304 | } |
| 1305 | EXPORT_SYMBOL(add_random_ready_callback); |
| 1306 | |
| 1307 | /* |
| 1308 | * Delete a previously registered readiness callback function. |
| 1309 | */ |
| 1310 | void del_random_ready_callback(struct random_ready_callback *rdy) |
| 1311 | { |
| 1312 | unsigned long flags; |
| 1313 | struct module *owner = NULL; |
| 1314 | |
| 1315 | spin_lock_irqsave(&random_ready_list_lock, flags); |
| 1316 | if (!list_empty(&rdy->list)) { |
| 1317 | list_del_init(&rdy->list); |
| 1318 | owner = rdy->owner; |
| 1319 | } |
| 1320 | spin_unlock_irqrestore(&random_ready_list_lock, flags); |
| 1321 | |
| 1322 | module_put(owner); |
| 1323 | } |
| 1324 | EXPORT_SYMBOL(del_random_ready_callback); |
| 1325 | |
| 1326 | /* |
Theodore Ts'o | c2557a3 | 2012-07-05 10:35:23 -0400 | [diff] [blame] | 1327 | * This function will use the architecture-specific hardware random |
| 1328 | * number generator if it is available. The arch-specific hw RNG will |
| 1329 | * almost certainly be faster than what we can do in software, but it |
| 1330 | * is impossible to verify that it is implemented securely (as |
| 1331 | * opposed, to, say, the AES encryption of a sequence number using a |
| 1332 | * key known by the NSA). So it's useful if we need the speed, but |
| 1333 | * only if we're willing to trust the hardware manufacturer not to |
| 1334 | * have put in a back door. |
| 1335 | */ |
| 1336 | void get_random_bytes_arch(void *buf, int nbytes) |
| 1337 | { |
H. Peter Anvin | 63d7717 | 2011-07-31 13:54:50 -0700 | [diff] [blame] | 1338 | char *p = buf; |
| 1339 | |
Theodore Ts'o | 5910895 | 2013-09-12 14:10:25 -0400 | [diff] [blame] | 1340 | trace_get_random_bytes_arch(nbytes, _RET_IP_); |
H. Peter Anvin | 63d7717 | 2011-07-31 13:54:50 -0700 | [diff] [blame] | 1341 | while (nbytes) { |
| 1342 | unsigned long v; |
| 1343 | int chunk = min(nbytes, (int)sizeof(unsigned long)); |
Theodore Ts'o | c2557a3 | 2012-07-05 10:35:23 -0400 | [diff] [blame] | 1344 | |
H. Peter Anvin | 63d7717 | 2011-07-31 13:54:50 -0700 | [diff] [blame] | 1345 | if (!arch_get_random_long(&v)) |
| 1346 | break; |
| 1347 | |
Luck, Tony | bd29e56 | 2011-11-16 10:50:56 -0800 | [diff] [blame] | 1348 | memcpy(p, &v, chunk); |
H. Peter Anvin | 63d7717 | 2011-07-31 13:54:50 -0700 | [diff] [blame] | 1349 | p += chunk; |
| 1350 | nbytes -= chunk; |
| 1351 | } |
| 1352 | |
Theodore Ts'o | c2557a3 | 2012-07-05 10:35:23 -0400 | [diff] [blame] | 1353 | if (nbytes) |
| 1354 | extract_entropy(&nonblocking_pool, p, nbytes, 0, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1355 | } |
Theodore Ts'o | c2557a3 | 2012-07-05 10:35:23 -0400 | [diff] [blame] | 1356 | EXPORT_SYMBOL(get_random_bytes_arch); |
| 1357 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1358 | |
| 1359 | /* |
| 1360 | * init_std_data - initialize pool with system data |
| 1361 | * |
| 1362 | * @r: pool to initialize |
| 1363 | * |
| 1364 | * This function clears the pool's entropy count and mixes some system |
| 1365 | * data into the pool to prepare it for use. The pool is not cleared |
| 1366 | * as that can only decrease the entropy in the pool. |
| 1367 | */ |
| 1368 | static void init_std_data(struct entropy_store *r) |
| 1369 | { |
Theodore Ts'o | 3e88bdf | 2011-12-22 16:28:01 -0500 | [diff] [blame] | 1370 | int i; |
Theodore Ts'o | 902c098 | 2012-07-04 10:38:30 -0400 | [diff] [blame] | 1371 | ktime_t now = ktime_get_real(); |
| 1372 | unsigned long rv; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1373 | |
Theodore Ts'o | f5c2742 | 2013-09-22 15:14:32 -0400 | [diff] [blame] | 1374 | r->last_pulled = jiffies; |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 1375 | mix_pool_bytes(r, &now, sizeof(now)); |
H. Peter Anvin | 9ed17b7 | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1376 | for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) { |
H. Peter Anvin | 83664a6 | 2014-03-17 16:36:28 -0700 | [diff] [blame] | 1377 | if (!arch_get_random_seed_long(&rv) && |
| 1378 | !arch_get_random_long(&rv)) |
Theodore Ts'o | ae9ecd9 | 2013-11-03 07:56:17 -0500 | [diff] [blame] | 1379 | rv = random_get_entropy(); |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 1380 | mix_pool_bytes(r, &rv, sizeof(rv)); |
Theodore Ts'o | 3e88bdf | 2011-12-22 16:28:01 -0500 | [diff] [blame] | 1381 | } |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 1382 | mix_pool_bytes(r, utsname(), sizeof(*(utsname()))); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1383 | } |
| 1384 | |
Tony Luck | cbc96b7 | 2012-07-23 09:47:57 -0700 | [diff] [blame] | 1385 | /* |
| 1386 | * Note that setup_arch() may call add_device_randomness() |
| 1387 | * long before we get here. This allows seeding of the pools |
| 1388 | * with some platform dependent data very early in the boot |
| 1389 | * process. But it limits our options here. We must use |
| 1390 | * statically allocated structures that already have all |
| 1391 | * initializations complete at compile time. We should also |
| 1392 | * take care not to overwrite the precious per platform data |
| 1393 | * we were given. |
| 1394 | */ |
Matt Mackall | 53c3f63 | 2008-04-29 01:02:58 -0700 | [diff] [blame] | 1395 | static int rand_initialize(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1396 | { |
| 1397 | init_std_data(&input_pool); |
| 1398 | init_std_data(&blocking_pool); |
| 1399 | init_std_data(&nonblocking_pool); |
| 1400 | return 0; |
| 1401 | } |
Theodore Ts'o | ae9ecd9 | 2013-11-03 07:56:17 -0500 | [diff] [blame] | 1402 | early_initcall(rand_initialize); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1403 | |
David Howells | 9361401 | 2006-09-30 20:45:40 +0200 | [diff] [blame] | 1404 | #ifdef CONFIG_BLOCK |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1405 | void rand_initialize_disk(struct gendisk *disk) |
| 1406 | { |
| 1407 | struct timer_rand_state *state; |
| 1408 | |
| 1409 | /* |
Eric Dumazet | f859581 | 2007-03-28 14:22:33 -0700 | [diff] [blame] | 1410 | * If kzalloc returns null, we just won't use that entropy |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1411 | * source. |
| 1412 | */ |
Eric Dumazet | f859581 | 2007-03-28 14:22:33 -0700 | [diff] [blame] | 1413 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
Theodore Ts'o | 644008d | 2013-11-03 16:40:53 -0500 | [diff] [blame] | 1414 | if (state) { |
| 1415 | state->last_time = INITIAL_JIFFIES; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1416 | disk->random = state; |
Theodore Ts'o | 644008d | 2013-11-03 16:40:53 -0500 | [diff] [blame] | 1417 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1418 | } |
David Howells | 9361401 | 2006-09-30 20:45:40 +0200 | [diff] [blame] | 1419 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1420 | |
| 1421 | static ssize_t |
Theodore Ts'o | c6e9d6f | 2014-07-17 04:13:05 -0400 | [diff] [blame] | 1422 | _random_read(int nonblock, char __user *buf, size_t nbytes) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1423 | { |
Greg Price | 12ff3a5 | 2013-11-29 15:02:33 -0500 | [diff] [blame] | 1424 | ssize_t n; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1425 | |
| 1426 | if (nbytes == 0) |
| 1427 | return 0; |
| 1428 | |
Greg Price | 12ff3a5 | 2013-11-29 15:02:33 -0500 | [diff] [blame] | 1429 | nbytes = min_t(size_t, nbytes, SEC_XFER_SIZE); |
| 1430 | while (1) { |
| 1431 | n = extract_entropy_user(&blocking_pool, buf, nbytes); |
| 1432 | if (n < 0) |
| 1433 | return n; |
Theodore Ts'o | f80bbd8 | 2013-10-03 12:02:37 -0400 | [diff] [blame] | 1434 | trace_random_read(n*8, (nbytes-n)*8, |
| 1435 | ENTROPY_BITS(&blocking_pool), |
| 1436 | ENTROPY_BITS(&input_pool)); |
Greg Price | 12ff3a5 | 2013-11-29 15:02:33 -0500 | [diff] [blame] | 1437 | if (n > 0) |
| 1438 | return n; |
H. Peter Anvin | 331c649 | 2014-03-17 16:36:29 -0700 | [diff] [blame] | 1439 | |
Greg Price | 12ff3a5 | 2013-11-29 15:02:33 -0500 | [diff] [blame] | 1440 | /* Pool is (near) empty. Maybe wait and retry. */ |
Theodore Ts'o | c6e9d6f | 2014-07-17 04:13:05 -0400 | [diff] [blame] | 1441 | if (nonblock) |
Greg Price | 12ff3a5 | 2013-11-29 15:02:33 -0500 | [diff] [blame] | 1442 | return -EAGAIN; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1443 | |
Greg Price | 12ff3a5 | 2013-11-29 15:02:33 -0500 | [diff] [blame] | 1444 | wait_event_interruptible(random_read_wait, |
| 1445 | ENTROPY_BITS(&input_pool) >= |
Greg Price | 2132a96 | 2013-12-06 21:28:03 -0500 | [diff] [blame] | 1446 | random_read_wakeup_bits); |
Greg Price | 12ff3a5 | 2013-11-29 15:02:33 -0500 | [diff] [blame] | 1447 | if (signal_pending(current)) |
| 1448 | return -ERESTARTSYS; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1449 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1450 | } |
| 1451 | |
| 1452 | static ssize_t |
Theodore Ts'o | c6e9d6f | 2014-07-17 04:13:05 -0400 | [diff] [blame] | 1453 | random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
| 1454 | { |
| 1455 | return _random_read(file->f_flags & O_NONBLOCK, buf, nbytes); |
| 1456 | } |
| 1457 | |
| 1458 | static ssize_t |
Matt Mackall | 90b75ee | 2008-04-29 01:02:55 -0700 | [diff] [blame] | 1459 | urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1460 | { |
Theodore Ts'o | 301f059 | 2013-11-03 06:54:51 -0500 | [diff] [blame] | 1461 | int ret; |
| 1462 | |
| 1463 | if (unlikely(nonblocking_pool.initialized == 0)) |
| 1464 | printk_once(KERN_NOTICE "random: %s urandom read " |
| 1465 | "with %d bits of entropy available\n", |
| 1466 | current->comm, nonblocking_pool.entropy_total); |
| 1467 | |
Hannes Frederic Sowa | 79a8468 | 2014-07-18 17:26:41 -0400 | [diff] [blame] | 1468 | nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3)); |
Theodore Ts'o | 301f059 | 2013-11-03 06:54:51 -0500 | [diff] [blame] | 1469 | ret = extract_entropy_user(&nonblocking_pool, buf, nbytes); |
Theodore Ts'o | f80bbd8 | 2013-10-03 12:02:37 -0400 | [diff] [blame] | 1470 | |
| 1471 | trace_urandom_read(8 * nbytes, ENTROPY_BITS(&nonblocking_pool), |
| 1472 | ENTROPY_BITS(&input_pool)); |
| 1473 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1474 | } |
| 1475 | |
| 1476 | static unsigned int |
| 1477 | random_poll(struct file *file, poll_table * wait) |
| 1478 | { |
| 1479 | unsigned int mask; |
| 1480 | |
| 1481 | poll_wait(file, &random_read_wait, wait); |
| 1482 | poll_wait(file, &random_write_wait, wait); |
| 1483 | mask = 0; |
Greg Price | 2132a96 | 2013-12-06 21:28:03 -0500 | [diff] [blame] | 1484 | if (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1485 | mask |= POLLIN | POLLRDNORM; |
Greg Price | 2132a96 | 2013-12-06 21:28:03 -0500 | [diff] [blame] | 1486 | if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1487 | mask |= POLLOUT | POLLWRNORM; |
| 1488 | return mask; |
| 1489 | } |
| 1490 | |
Matt Mackall | 7f397dc | 2007-05-29 21:58:10 -0500 | [diff] [blame] | 1491 | static int |
| 1492 | write_pool(struct entropy_store *r, const char __user *buffer, size_t count) |
| 1493 | { |
| 1494 | size_t bytes; |
| 1495 | __u32 buf[16]; |
| 1496 | const char __user *p = buffer; |
| 1497 | |
| 1498 | while (count > 0) { |
| 1499 | bytes = min(count, sizeof(buf)); |
| 1500 | if (copy_from_user(&buf, p, bytes)) |
| 1501 | return -EFAULT; |
| 1502 | |
| 1503 | count -= bytes; |
| 1504 | p += bytes; |
| 1505 | |
Theodore Ts'o | 85608f8 | 2014-06-10 23:09:20 -0400 | [diff] [blame] | 1506 | mix_pool_bytes(r, buf, bytes); |
Matt Mackall | 91f3f1e | 2008-02-06 01:37:20 -0800 | [diff] [blame] | 1507 | cond_resched(); |
Matt Mackall | 7f397dc | 2007-05-29 21:58:10 -0500 | [diff] [blame] | 1508 | } |
| 1509 | |
| 1510 | return 0; |
| 1511 | } |
| 1512 | |
Matt Mackall | 90b75ee | 2008-04-29 01:02:55 -0700 | [diff] [blame] | 1513 | static ssize_t random_write(struct file *file, const char __user *buffer, |
| 1514 | size_t count, loff_t *ppos) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1515 | { |
Matt Mackall | 7f397dc | 2007-05-29 21:58:10 -0500 | [diff] [blame] | 1516 | size_t ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1517 | |
Matt Mackall | 7f397dc | 2007-05-29 21:58:10 -0500 | [diff] [blame] | 1518 | ret = write_pool(&blocking_pool, buffer, count); |
| 1519 | if (ret) |
| 1520 | return ret; |
| 1521 | ret = write_pool(&nonblocking_pool, buffer, count); |
| 1522 | if (ret) |
| 1523 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1524 | |
Matt Mackall | 7f397dc | 2007-05-29 21:58:10 -0500 | [diff] [blame] | 1525 | return (ssize_t)count; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1526 | } |
| 1527 | |
Matt Mackall | 43ae486 | 2008-04-29 01:02:58 -0700 | [diff] [blame] | 1528 | static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1529 | { |
| 1530 | int size, ent_count; |
| 1531 | int __user *p = (int __user *)arg; |
| 1532 | int retval; |
| 1533 | |
| 1534 | switch (cmd) { |
| 1535 | case RNDGETENTCNT: |
Matt Mackall | 43ae486 | 2008-04-29 01:02:58 -0700 | [diff] [blame] | 1536 | /* inherently racy, no point locking */ |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1537 | ent_count = ENTROPY_BITS(&input_pool); |
| 1538 | if (put_user(ent_count, p)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1539 | return -EFAULT; |
| 1540 | return 0; |
| 1541 | case RNDADDTOENTCNT: |
| 1542 | if (!capable(CAP_SYS_ADMIN)) |
| 1543 | return -EPERM; |
| 1544 | if (get_user(ent_count, p)) |
| 1545 | return -EFAULT; |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1546 | credit_entropy_bits_safe(&input_pool, ent_count); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1547 | return 0; |
| 1548 | case RNDADDENTROPY: |
| 1549 | if (!capable(CAP_SYS_ADMIN)) |
| 1550 | return -EPERM; |
| 1551 | if (get_user(ent_count, p++)) |
| 1552 | return -EFAULT; |
| 1553 | if (ent_count < 0) |
| 1554 | return -EINVAL; |
| 1555 | if (get_user(size, p++)) |
| 1556 | return -EFAULT; |
Matt Mackall | 7f397dc | 2007-05-29 21:58:10 -0500 | [diff] [blame] | 1557 | retval = write_pool(&input_pool, (const char __user *)p, |
| 1558 | size); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1559 | if (retval < 0) |
| 1560 | return retval; |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1561 | credit_entropy_bits_safe(&input_pool, ent_count); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1562 | return 0; |
| 1563 | case RNDZAPENTCNT: |
| 1564 | case RNDCLEARPOOL: |
Theodore Ts'o | ae9ecd9 | 2013-11-03 07:56:17 -0500 | [diff] [blame] | 1565 | /* |
| 1566 | * Clear the entropy pool counters. We no longer clear |
| 1567 | * the entropy pool, as that's silly. |
| 1568 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1569 | if (!capable(CAP_SYS_ADMIN)) |
| 1570 | return -EPERM; |
Theodore Ts'o | ae9ecd9 | 2013-11-03 07:56:17 -0500 | [diff] [blame] | 1571 | input_pool.entropy_count = 0; |
| 1572 | nonblocking_pool.entropy_count = 0; |
| 1573 | blocking_pool.entropy_count = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1574 | return 0; |
| 1575 | default: |
| 1576 | return -EINVAL; |
| 1577 | } |
| 1578 | } |
| 1579 | |
Jeff Dike | 9a6f70b | 2008-04-29 01:03:08 -0700 | [diff] [blame] | 1580 | static int random_fasync(int fd, struct file *filp, int on) |
| 1581 | { |
| 1582 | return fasync_helper(fd, filp, on, &fasync); |
| 1583 | } |
| 1584 | |
Arjan van de Ven | 2b8693c | 2007-02-12 00:55:32 -0800 | [diff] [blame] | 1585 | const struct file_operations random_fops = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1586 | .read = random_read, |
| 1587 | .write = random_write, |
| 1588 | .poll = random_poll, |
Matt Mackall | 43ae486 | 2008-04-29 01:02:58 -0700 | [diff] [blame] | 1589 | .unlocked_ioctl = random_ioctl, |
Jeff Dike | 9a6f70b | 2008-04-29 01:03:08 -0700 | [diff] [blame] | 1590 | .fasync = random_fasync, |
Arnd Bergmann | 6038f37 | 2010-08-15 18:52:59 +0200 | [diff] [blame] | 1591 | .llseek = noop_llseek, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1592 | }; |
| 1593 | |
Arjan van de Ven | 2b8693c | 2007-02-12 00:55:32 -0800 | [diff] [blame] | 1594 | const struct file_operations urandom_fops = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1595 | .read = urandom_read, |
| 1596 | .write = random_write, |
Matt Mackall | 43ae486 | 2008-04-29 01:02:58 -0700 | [diff] [blame] | 1597 | .unlocked_ioctl = random_ioctl, |
Jeff Dike | 9a6f70b | 2008-04-29 01:03:08 -0700 | [diff] [blame] | 1598 | .fasync = random_fasync, |
Arnd Bergmann | 6038f37 | 2010-08-15 18:52:59 +0200 | [diff] [blame] | 1599 | .llseek = noop_llseek, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1600 | }; |
| 1601 | |
Theodore Ts'o | c6e9d6f | 2014-07-17 04:13:05 -0400 | [diff] [blame] | 1602 | SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, |
| 1603 | unsigned int, flags) |
| 1604 | { |
| 1605 | if (flags & ~(GRND_NONBLOCK|GRND_RANDOM)) |
| 1606 | return -EINVAL; |
| 1607 | |
| 1608 | if (count > INT_MAX) |
| 1609 | count = INT_MAX; |
| 1610 | |
| 1611 | if (flags & GRND_RANDOM) |
| 1612 | return _random_read(flags & GRND_NONBLOCK, buf, count); |
| 1613 | |
| 1614 | if (unlikely(nonblocking_pool.initialized == 0)) { |
| 1615 | if (flags & GRND_NONBLOCK) |
| 1616 | return -EAGAIN; |
| 1617 | wait_event_interruptible(urandom_init_wait, |
| 1618 | nonblocking_pool.initialized); |
| 1619 | if (signal_pending(current)) |
| 1620 | return -ERESTARTSYS; |
| 1621 | } |
| 1622 | return urandom_read(NULL, buf, count, NULL); |
| 1623 | } |
| 1624 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1625 | /******************************************************************** |
| 1626 | * |
| 1627 | * Sysctl interface |
| 1628 | * |
| 1629 | ********************************************************************/ |
| 1630 | |
| 1631 | #ifdef CONFIG_SYSCTL |
| 1632 | |
| 1633 | #include <linux/sysctl.h> |
| 1634 | |
| 1635 | static int min_read_thresh = 8, min_write_thresh; |
Greg Price | 8c2aa33 | 2013-12-05 19:19:29 -0500 | [diff] [blame] | 1636 | static int max_read_thresh = OUTPUT_POOL_WORDS * 32; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1637 | static int max_write_thresh = INPUT_POOL_WORDS * 32; |
| 1638 | static char sysctl_bootid[16]; |
| 1639 | |
| 1640 | /* |
Greg Price | f22052b | 2013-11-29 14:58:16 -0500 | [diff] [blame] | 1641 | * This function is used to return both the bootid UUID, and random |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1642 | * UUID. The difference is in whether table->data is NULL; if it is, |
| 1643 | * then a new UUID is generated and returned to the user. |
| 1644 | * |
Greg Price | f22052b | 2013-11-29 14:58:16 -0500 | [diff] [blame] | 1645 | * If the user accesses this via the proc interface, the UUID will be |
| 1646 | * returned as an ASCII string in the standard UUID format; if via the |
| 1647 | * sysctl system call, as 16 bytes of binary data. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1648 | */ |
Joe Perches | a151427 | 2013-06-13 19:37:35 -0700 | [diff] [blame] | 1649 | static int proc_do_uuid(struct ctl_table *table, int write, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1650 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 1651 | { |
Joe Perches | a151427 | 2013-06-13 19:37:35 -0700 | [diff] [blame] | 1652 | struct ctl_table fake_table; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1653 | unsigned char buf[64], tmp_uuid[16], *uuid; |
| 1654 | |
| 1655 | uuid = table->data; |
| 1656 | if (!uuid) { |
| 1657 | uuid = tmp_uuid; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1658 | generate_random_uuid(uuid); |
Mathieu Desnoyers | 44e4360 | 2012-04-12 12:49:12 -0700 | [diff] [blame] | 1659 | } else { |
| 1660 | static DEFINE_SPINLOCK(bootid_spinlock); |
| 1661 | |
| 1662 | spin_lock(&bootid_spinlock); |
| 1663 | if (!uuid[8]) |
| 1664 | generate_random_uuid(uuid); |
| 1665 | spin_unlock(&bootid_spinlock); |
| 1666 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1667 | |
Joe Perches | 3590077 | 2009-12-14 18:01:11 -0800 | [diff] [blame] | 1668 | sprintf(buf, "%pU", uuid); |
| 1669 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1670 | fake_table.data = buf; |
| 1671 | fake_table.maxlen = sizeof(buf); |
| 1672 | |
Alexey Dobriyan | 8d65af7 | 2009-09-23 15:57:19 -0700 | [diff] [blame] | 1673 | return proc_dostring(&fake_table, write, buffer, lenp, ppos); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1674 | } |
| 1675 | |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1676 | /* |
| 1677 | * Return entropy available scaled to integral bits |
| 1678 | */ |
Joe Perches | 5eb10d9 | 2014-06-06 14:37:58 -0700 | [diff] [blame] | 1679 | static int proc_do_entropy(struct ctl_table *table, int write, |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1680 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 1681 | { |
Joe Perches | 5eb10d9 | 2014-06-06 14:37:58 -0700 | [diff] [blame] | 1682 | struct ctl_table fake_table; |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1683 | int entropy_count; |
| 1684 | |
| 1685 | entropy_count = *(int *)table->data >> ENTROPY_SHIFT; |
| 1686 | |
| 1687 | fake_table.data = &entropy_count; |
| 1688 | fake_table.maxlen = sizeof(entropy_count); |
| 1689 | |
| 1690 | return proc_dointvec(&fake_table, write, buffer, lenp, ppos); |
| 1691 | } |
| 1692 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1693 | static int sysctl_poolsize = INPUT_POOL_WORDS * 32; |
Joe Perches | a151427 | 2013-06-13 19:37:35 -0700 | [diff] [blame] | 1694 | extern struct ctl_table random_table[]; |
| 1695 | struct ctl_table random_table[] = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1696 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1697 | .procname = "poolsize", |
| 1698 | .data = &sysctl_poolsize, |
| 1699 | .maxlen = sizeof(int), |
| 1700 | .mode = 0444, |
Eric W. Biederman | 6d45611 | 2009-11-16 03:11:48 -0800 | [diff] [blame] | 1701 | .proc_handler = proc_dointvec, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1702 | }, |
| 1703 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1704 | .procname = "entropy_avail", |
| 1705 | .maxlen = sizeof(int), |
| 1706 | .mode = 0444, |
H. Peter Anvin | a283b5c | 2013-09-10 23:16:17 -0400 | [diff] [blame] | 1707 | .proc_handler = proc_do_entropy, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1708 | .data = &input_pool.entropy_count, |
| 1709 | }, |
| 1710 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1711 | .procname = "read_wakeup_threshold", |
Greg Price | 2132a96 | 2013-12-06 21:28:03 -0500 | [diff] [blame] | 1712 | .data = &random_read_wakeup_bits, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1713 | .maxlen = sizeof(int), |
| 1714 | .mode = 0644, |
Eric W. Biederman | 6d45611 | 2009-11-16 03:11:48 -0800 | [diff] [blame] | 1715 | .proc_handler = proc_dointvec_minmax, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1716 | .extra1 = &min_read_thresh, |
| 1717 | .extra2 = &max_read_thresh, |
| 1718 | }, |
| 1719 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1720 | .procname = "write_wakeup_threshold", |
Greg Price | 2132a96 | 2013-12-06 21:28:03 -0500 | [diff] [blame] | 1721 | .data = &random_write_wakeup_bits, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1722 | .maxlen = sizeof(int), |
| 1723 | .mode = 0644, |
Eric W. Biederman | 6d45611 | 2009-11-16 03:11:48 -0800 | [diff] [blame] | 1724 | .proc_handler = proc_dointvec_minmax, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1725 | .extra1 = &min_write_thresh, |
| 1726 | .extra2 = &max_write_thresh, |
| 1727 | }, |
| 1728 | { |
Theodore Ts'o | f5c2742 | 2013-09-22 15:14:32 -0400 | [diff] [blame] | 1729 | .procname = "urandom_min_reseed_secs", |
| 1730 | .data = &random_min_urandom_seed, |
| 1731 | .maxlen = sizeof(int), |
| 1732 | .mode = 0644, |
| 1733 | .proc_handler = proc_dointvec, |
| 1734 | }, |
| 1735 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1736 | .procname = "boot_id", |
| 1737 | .data = &sysctl_bootid, |
| 1738 | .maxlen = 16, |
| 1739 | .mode = 0444, |
Eric W. Biederman | 6d45611 | 2009-11-16 03:11:48 -0800 | [diff] [blame] | 1740 | .proc_handler = proc_do_uuid, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1741 | }, |
| 1742 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1743 | .procname = "uuid", |
| 1744 | .maxlen = 16, |
| 1745 | .mode = 0444, |
Eric W. Biederman | 6d45611 | 2009-11-16 03:11:48 -0800 | [diff] [blame] | 1746 | .proc_handler = proc_do_uuid, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1747 | }, |
Theodore Ts'o | 43759d4 | 2014-06-14 21:43:13 -0400 | [diff] [blame] | 1748 | #ifdef ADD_INTERRUPT_BENCH |
| 1749 | { |
| 1750 | .procname = "add_interrupt_avg_cycles", |
| 1751 | .data = &avg_cycles, |
| 1752 | .maxlen = sizeof(avg_cycles), |
| 1753 | .mode = 0444, |
| 1754 | .proc_handler = proc_doulongvec_minmax, |
| 1755 | }, |
| 1756 | { |
| 1757 | .procname = "add_interrupt_avg_deviation", |
| 1758 | .data = &avg_deviation, |
| 1759 | .maxlen = sizeof(avg_deviation), |
| 1760 | .mode = 0444, |
| 1761 | .proc_handler = proc_doulongvec_minmax, |
| 1762 | }, |
| 1763 | #endif |
Eric W. Biederman | 894d249 | 2009-11-05 14:34:02 -0800 | [diff] [blame] | 1764 | { } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1765 | }; |
| 1766 | #endif /* CONFIG_SYSCTL */ |
| 1767 | |
David S. Miller | 6e5714e | 2011-08-03 20:50:44 -0700 | [diff] [blame] | 1768 | static u32 random_int_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1769 | |
Theodore Ts'o | 47d06e5 | 2013-09-10 10:52:35 -0400 | [diff] [blame] | 1770 | int random_int_secret_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1771 | { |
David S. Miller | 6e5714e | 2011-08-03 20:50:44 -0700 | [diff] [blame] | 1772 | get_random_bytes(random_int_secret, sizeof(random_int_secret)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1773 | return 0; |
| 1774 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1775 | |
| 1776 | /* |
| 1777 | * Get a random word for internal kernel use only. Similar to urandom but |
| 1778 | * with the goal of minimal entropy pool depletion. As a result, the random |
| 1779 | * value is not cryptographically secure but for several uses the cost of |
| 1780 | * depleting entropy is too high |
| 1781 | */ |
Theodore Ts'o | 74feec5 | 2012-07-06 14:03:18 -0400 | [diff] [blame] | 1782 | static DEFINE_PER_CPU(__u32 [MD5_DIGEST_WORDS], get_random_int_hash); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1783 | unsigned int get_random_int(void) |
| 1784 | { |
H. Peter Anvin | 63d7717 | 2011-07-31 13:54:50 -0700 | [diff] [blame] | 1785 | __u32 *hash; |
David S. Miller | 6e5714e | 2011-08-03 20:50:44 -0700 | [diff] [blame] | 1786 | unsigned int ret; |
Linus Torvalds | 8a0a9bd | 2009-05-05 08:17:43 -0700 | [diff] [blame] | 1787 | |
H. Peter Anvin | 63d7717 | 2011-07-31 13:54:50 -0700 | [diff] [blame] | 1788 | if (arch_get_random_int(&ret)) |
| 1789 | return ret; |
| 1790 | |
| 1791 | hash = get_cpu_var(get_random_int_hash); |
Linus Torvalds | 8a0a9bd | 2009-05-05 08:17:43 -0700 | [diff] [blame] | 1792 | |
Theodore Ts'o | 61875f3 | 2013-09-21 13:58:22 -0400 | [diff] [blame] | 1793 | hash[0] += current->pid + jiffies + random_get_entropy(); |
David S. Miller | 6e5714e | 2011-08-03 20:50:44 -0700 | [diff] [blame] | 1794 | md5_transform(hash, random_int_secret); |
| 1795 | ret = hash[0]; |
Linus Torvalds | 8a0a9bd | 2009-05-05 08:17:43 -0700 | [diff] [blame] | 1796 | put_cpu_var(get_random_int_hash); |
| 1797 | |
| 1798 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1799 | } |
Andy Shevchenko | 16c7fa0 | 2013-04-30 15:27:30 -0700 | [diff] [blame] | 1800 | EXPORT_SYMBOL(get_random_int); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1801 | |
| 1802 | /* |
Daniel Cashman | ec9ee4a | 2016-02-26 15:19:34 -0800 | [diff] [blame] | 1803 | * Same as get_random_int(), but returns unsigned long. |
| 1804 | */ |
| 1805 | unsigned long get_random_long(void) |
| 1806 | { |
| 1807 | __u32 *hash; |
| 1808 | unsigned long ret; |
| 1809 | |
| 1810 | if (arch_get_random_long(&ret)) |
| 1811 | return ret; |
| 1812 | |
| 1813 | hash = get_cpu_var(get_random_int_hash); |
| 1814 | |
| 1815 | hash[0] += current->pid + jiffies + random_get_entropy(); |
| 1816 | md5_transform(hash, random_int_secret); |
| 1817 | ret = *(unsigned long *)hash; |
| 1818 | put_cpu_var(get_random_int_hash); |
| 1819 | |
| 1820 | return ret; |
| 1821 | } |
| 1822 | EXPORT_SYMBOL(get_random_long); |
| 1823 | |
| 1824 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1825 | * randomize_range() returns a start address such that |
| 1826 | * |
| 1827 | * [...... <range> .....] |
| 1828 | * start end |
| 1829 | * |
| 1830 | * a <range> with size "len" starting at the return value is inside in the |
| 1831 | * area defined by [start, end], but is otherwise randomized. |
| 1832 | */ |
| 1833 | unsigned long |
| 1834 | randomize_range(unsigned long start, unsigned long end, unsigned long len) |
| 1835 | { |
| 1836 | unsigned long range = end - len - start; |
| 1837 | |
| 1838 | if (end <= start + len) |
| 1839 | return 0; |
| 1840 | return PAGE_ALIGN(get_random_int() % range + start); |
| 1841 | } |
Torsten Duwe | c84dbf6 | 2014-06-14 23:38:36 -0400 | [diff] [blame] | 1842 | |
| 1843 | /* Interface for in-kernel drivers of true hardware RNGs. |
| 1844 | * Those devices may produce endless random bits and will be throttled |
| 1845 | * when our pool is full. |
| 1846 | */ |
| 1847 | void add_hwgenerator_randomness(const char *buffer, size_t count, |
| 1848 | size_t entropy) |
| 1849 | { |
| 1850 | struct entropy_store *poolp = &input_pool; |
| 1851 | |
| 1852 | /* Suspend writing if we're above the trickle threshold. |
| 1853 | * We'll be woken up again once below random_write_wakeup_thresh, |
| 1854 | * or when the calling thread is about to terminate. |
| 1855 | */ |
| 1856 | wait_event_interruptible(random_write_wait, kthread_should_stop() || |
| 1857 | ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits); |
| 1858 | mix_pool_bytes(poolp, buffer, count); |
| 1859 | credit_entropy_bits(poolp, entropy); |
| 1860 | } |
| 1861 | EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); |