| /* |
| * random.c -- A strong random number generator |
| * |
| * Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All |
| * Rights Reserved. |
| * |
| * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005 |
| * |
| * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All |
| * rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, and the entire permission notice in its entirety, |
| * including the disclaimer of warranties. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 3. The name of the author may not be used to endorse or promote |
| * products derived from this software without specific prior |
| * written permission. |
| * |
| * ALTERNATIVELY, this product may be distributed under the terms of |
| * the GNU General Public License, in which case the provisions of the GPL are |
| * required INSTEAD OF the above restrictions. (This clause is |
| * necessary due to a potential bad interaction between the GPL and |
| * the restrictions contained in a BSD-style copyright.) |
| * |
| * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF |
| * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE |
| * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT |
| * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR |
| * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE |
| * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH |
| * DAMAGE. |
| */ |
| |
| /* |
| * (now, with legal B.S. out of the way.....) |
| * |
| * This routine gathers environmental noise from device drivers, etc., |
| * and returns good random numbers, suitable for cryptographic use. |
| * Besides the obvious cryptographic uses, these numbers are also good |
| * for seeding TCP sequence numbers, and other places where it is |
| * desirable to have numbers which are not only random, but hard to |
| * predict by an attacker. |
| * |
| * Theory of operation |
| * =================== |
| * |
| * Computers are very predictable devices. Hence it is extremely hard |
| * to produce truly random numbers on a computer --- as opposed to |
| * pseudo-random numbers, which can easily generated by using a |
| * algorithm. Unfortunately, it is very easy for attackers to guess |
| * the sequence of pseudo-random number generators, and for some |
| * applications this is not acceptable. So instead, we must try to |
| * gather "environmental noise" from the computer's environment, which |
| * must be hard for outside attackers to observe, and use that to |
| * generate random numbers. In a Unix environment, this is best done |
| * from inside the kernel. |
| * |
| * Sources of randomness from the environment include inter-keyboard |
| * timings, inter-interrupt timings from some interrupts, and other |
| * events which are both (a) non-deterministic and (b) hard for an |
| * outside observer to measure. Randomness from these sources are |
| * added to an "entropy pool", which is mixed using a CRC-like function. |
| * This is not cryptographically strong, but it is adequate assuming |
| * the randomness is not chosen maliciously, and it is fast enough that |
| * the overhead of doing it on every interrupt is very reasonable. |
| * As random bytes are mixed into the entropy pool, the routines keep |
| * an *estimate* of how many bits of randomness have been stored into |
| * the random number generator's internal state. |
| * |
| * When random bytes are desired, they are obtained by taking the SHA |
| * hash of the contents of the "entropy pool". The SHA hash avoids |
| * exposing the internal state of the entropy pool. It is believed to |
| * be computationally infeasible to derive any useful information |
| * about the input of SHA from its output. Even if it is possible to |
| * analyze SHA in some clever way, as long as the amount of data |
| * returned from the generator is less than the inherent entropy in |
| * the pool, the output data is totally unpredictable. For this |
| * reason, the routine decreases its internal estimate of how many |
| * bits of "true randomness" are contained in the entropy pool as it |
| * outputs random numbers. |
| * |
| * If this estimate goes to zero, the routine can still generate |
| * random numbers; however, an attacker may (at least in theory) be |
| * able to infer the future output of the generator from prior |
| * outputs. This requires successful cryptanalysis of SHA, which is |
| * not believed to be feasible, but there is a remote possibility. |
| * Nonetheless, these numbers should be useful for the vast majority |
| * of purposes. |
| * |
| * Exported interfaces ---- output |
| * =============================== |
| * |
| * There are three exported interfaces; the first is one designed to |
| * be used from within the kernel: |
| * |
| * void get_random_bytes(void *buf, int nbytes); |
| * |
| * This interface will return the requested number of random bytes, |
| * and place it in the requested buffer. |
| * |
| * The two other interfaces are two character devices /dev/random and |
| * /dev/urandom. /dev/random is suitable for use when very high |
| * quality randomness is desired (for example, for key generation or |
| * one-time pads), as it will only return a maximum of the number of |
| * bits of randomness (as estimated by the random number generator) |
| * contained in the entropy pool. |
| * |
| * The /dev/urandom device does not have this limit, and will return |
| * as many bytes as are requested. As more and more random bytes are |
| * requested without giving time for the entropy pool to recharge, |
| * this will result in random numbers that are merely cryptographically |
| * strong. For many applications, however, this is acceptable. |
| * |
| * Exported interfaces ---- input |
| * ============================== |
| * |
| * The current exported interfaces for gathering environmental noise |
| * from the devices are: |
| * |
| * void add_device_randomness(const void *buf, unsigned int size); |
| * void add_input_randomness(unsigned int type, unsigned int code, |
| * unsigned int value); |
| * void add_interrupt_randomness(int irq, int irq_flags); |
| * void add_disk_randomness(struct gendisk *disk); |
| * |
| * add_device_randomness() is for adding data to the random pool that |
| * is likely to differ between two devices (or possibly even per boot). |
| * This would be things like MAC addresses or serial numbers, or the |
| * read-out of the RTC. This does *not* add any actual entropy to the |
| * pool, but it initializes the pool to different values for devices |
| * that might otherwise be identical and have very little entropy |
| * available to them (particularly common in the embedded world). |
| * |
| * add_input_randomness() uses the input layer interrupt timing, as well as |
| * the event type information from the hardware. |
| * |
| * add_interrupt_randomness() uses the interrupt timing as random |
| * inputs to the entropy pool. Using the cycle counters and the irq source |
| * as inputs, it feeds the randomness roughly once a second. |
| * |
| * add_disk_randomness() uses what amounts to the seek time of block |
| * layer request events, on a per-disk_devt basis, as input to the |
| * entropy pool. Note that high-speed solid state drives with very low |
| * seek times do not make for good sources of entropy, as their seek |
| * times are usually fairly consistent. |
| * |
| * All of these routines try to estimate how many bits of randomness a |
| * particular randomness source. They do this by keeping track of the |
| * first and second order deltas of the event timings. |
| * |
| * Ensuring unpredictability at system startup |
| * ============================================ |
| * |
| * When any operating system starts up, it will go through a sequence |
| * of actions that are fairly predictable by an adversary, especially |
| * if the start-up does not involve interaction with a human operator. |
| * This reduces the actual number of bits of unpredictability in the |
| * entropy pool below the value in entropy_count. In order to |
| * counteract this effect, it helps to carry information in the |
| * entropy pool across shut-downs and start-ups. To do this, put the |
| * following lines an appropriate script which is run during the boot |
| * sequence: |
| * |
| * echo "Initializing random number generator..." |
| * random_seed=/var/run/random-seed |
| * # Carry a random seed from start-up to start-up |
| * # Load and then save the whole entropy pool |
| * if [ -f $random_seed ]; then |
| * cat $random_seed >/dev/urandom |
| * else |
| * touch $random_seed |
| * fi |
| * chmod 600 $random_seed |
| * dd if=/dev/urandom of=$random_seed count=1 bs=512 |
| * |
| * and the following lines in an appropriate script which is run as |
| * the system is shutdown: |
| * |
| * # Carry a random seed from shut-down to start-up |
| * # Save the whole entropy pool |
| * echo "Saving random seed..." |
| * random_seed=/var/run/random-seed |
| * touch $random_seed |
| * chmod 600 $random_seed |
| * dd if=/dev/urandom of=$random_seed count=1 bs=512 |
| * |
| * For example, on most modern systems using the System V init |
| * scripts, such code fragments would be found in |
| * /etc/rc.d/init.d/random. On older Linux systems, the correct script |
| * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0. |
| * |
| * Effectively, these commands cause the contents of the entropy pool |
| * to be saved at shut-down time and reloaded into the entropy pool at |
| * start-up. (The 'dd' in the addition to the bootup script is to |
| * make sure that /etc/random-seed is different for every start-up, |
| * even if the system crashes without executing rc.0.) Even with |
| * complete knowledge of the start-up activities, predicting the state |
| * of the entropy pool requires knowledge of the previous history of |
| * the system. |
| * |
| * Configuring the /dev/random driver under Linux |
| * ============================================== |
| * |
| * The /dev/random driver under Linux uses minor numbers 8 and 9 of |
| * the /dev/mem major number (#1). So if your system does not have |
| * /dev/random and /dev/urandom created already, they can be created |
| * by using the commands: |
| * |
| * mknod /dev/random c 1 8 |
| * mknod /dev/urandom c 1 9 |
| * |
| * Acknowledgements: |
| * ================= |
| * |
| * Ideas for constructing this random number generator were derived |
| * from Pretty Good Privacy's random number generator, and from private |
| * discussions with Phil Karn. Colin Plumb provided a faster random |
| * number generator, which speed up the mixing function of the entropy |
| * pool, taken from PGPfone. Dale Worley has also contributed many |
| * useful ideas and suggestions to improve this driver. |
| * |
| * Any flaws in the design are solely my responsibility, and should |
| * not be attributed to the Phil, Colin, or any of authors of PGP. |
| * |
| * Further background information on this topic may be obtained from |
| * RFC 1750, "Randomness Recommendations for Security", by Donald |
| * Eastlake, Steve Crocker, and Jeff Schiller. |
| */ |
| |
| #include <linux/utsname.h> |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| #include <linux/major.h> |
| #include <linux/string.h> |
| #include <linux/fcntl.h> |
| #include <linux/slab.h> |
| #include <linux/random.h> |
| #include <linux/poll.h> |
| #include <linux/init.h> |
| #include <linux/fs.h> |
| #include <linux/genhd.h> |
| #include <linux/interrupt.h> |
| #include <linux/mm.h> |
| #include <linux/nodemask.h> |
| #include <linux/spinlock.h> |
| #include <linux/kthread.h> |
| #include <linux/percpu.h> |
| #include <linux/cryptohash.h> |
| #include <linux/fips.h> |
| #include <linux/ptrace.h> |
| #include <linux/kmemcheck.h> |
| #include <linux/workqueue.h> |
| #include <linux/irq.h> |
| #include <linux/ratelimit.h> |
| #include <linux/syscalls.h> |
| #include <linux/completion.h> |
| #include <linux/uuid.h> |
| #include <crypto/chacha20.h> |
| |
| #include <asm/processor.h> |
| #include <asm/uaccess.h> |
| #include <asm/irq.h> |
| #include <asm/irq_regs.h> |
| #include <asm/io.h> |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/random.h> |
| |
| /* #define ADD_INTERRUPT_BENCH */ |
| |
| /* |
| * Configuration information |
| */ |
| #define INPUT_POOL_SHIFT 12 |
| #define INPUT_POOL_WORDS (1 << (INPUT_POOL_SHIFT-5)) |
| #define OUTPUT_POOL_SHIFT 10 |
| #define OUTPUT_POOL_WORDS (1 << (OUTPUT_POOL_SHIFT-5)) |
| #define SEC_XFER_SIZE 512 |
| #define EXTRACT_SIZE 10 |
| |
| |
| #define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long)) |
| |
| /* |
| * To allow fractional bits to be tracked, the entropy_count field is |
| * denominated in units of 1/8th bits. |
| * |
| * 2*(ENTROPY_SHIFT + log2(poolbits)) must <= 31, or the multiply in |
| * credit_entropy_bits() needs to be 64 bits wide. |
| */ |
| #define ENTROPY_SHIFT 3 |
| #define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT) |
| |
| /* |
| * The minimum number of bits of entropy before we wake up a read on |
| * /dev/random. Should be enough to do a significant reseed. |
| */ |
| static int random_read_wakeup_bits = 64; |
| |
| /* |
| * If the entropy count falls under this number of bits, then we |
| * should wake up processes which are selecting or polling on write |
| * access to /dev/random. |
| */ |
| static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS; |
| |
| /* |
| * Originally, we used a primitive polynomial of degree .poolwords |
| * over GF(2). The taps for various sizes are defined below. They |
| * were chosen to be evenly spaced except for the last tap, which is 1 |
| * to get the twisting happening as fast as possible. |
| * |
| * For the purposes of better mixing, we use the CRC-32 polynomial as |
| * well to make a (modified) twisted Generalized Feedback Shift |
| * Register. (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR |
| * generators. ACM Transactions on Modeling and Computer Simulation |
| * 2(3):179-194. Also see M. Matsumoto & Y. Kurita, 1994. Twisted |
| * GFSR generators II. ACM Transactions on Modeling and Computer |
| * Simulation 4:254-266) |
| * |
| * Thanks to Colin Plumb for suggesting this. |
| * |
| * The mixing operation is much less sensitive than the output hash, |
| * where we use SHA-1. All that we want of mixing operation is that |
| * it be a good non-cryptographic hash; i.e. it not produce collisions |
| * when fed "random" data of the sort we expect to see. As long as |
| * the pool state differs for different inputs, we have preserved the |
| * input entropy and done a good job. The fact that an intelligent |
| * attacker can construct inputs that will produce controlled |
| * alterations to the pool's state is not important because we don't |
| * consider such inputs to contribute any randomness. The only |
| * property we need with respect to them is that the attacker can't |
| * increase his/her knowledge of the pool's state. Since all |
| * additions are reversible (knowing the final state and the input, |
| * you can reconstruct the initial state), if an attacker has any |
| * uncertainty about the initial state, he/she can only shuffle that |
| * uncertainty about, but never cause any collisions (which would |
| * decrease the uncertainty). |
| * |
| * Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and |
| * Videau in their paper, "The Linux Pseudorandom Number Generator |
| * Revisited" (see: http://eprint.iacr.org/2012/251.pdf). In their |
| * paper, they point out that we are not using a true Twisted GFSR, |
| * since Matsumoto & Kurita used a trinomial feedback polynomial (that |
| * is, with only three taps, instead of the six that we are using). |
| * As a result, the resulting polynomial is neither primitive nor |
| * irreducible, and hence does not have a maximal period over |
| * GF(2**32). They suggest a slight change to the generator |
| * polynomial which improves the resulting TGFSR polynomial to be |
| * irreducible, which we have made here. |
| */ |
| static struct poolinfo { |
| int poolbitshift, poolwords, poolbytes, poolbits, poolfracbits; |
| #define S(x) ilog2(x)+5, (x), (x)*4, (x)*32, (x) << (ENTROPY_SHIFT+5) |
| int tap1, tap2, tap3, tap4, tap5; |
| } poolinfo_table[] = { |
| /* was: x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 */ |
| /* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */ |
| { S(128), 104, 76, 51, 25, 1 }, |
| /* was: x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 */ |
| /* x^32 + x^26 + x^19 + x^14 + x^7 + x + 1 */ |
| { S(32), 26, 19, 14, 7, 1 }, |
| #if 0 |
| /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */ |
| { S(2048), 1638, 1231, 819, 411, 1 }, |
| |
| /* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */ |
| { S(1024), 817, 615, 412, 204, 1 }, |
| |
| /* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */ |
| { S(1024), 819, 616, 410, 207, 2 }, |
| |
| /* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */ |
| { S(512), 411, 308, 208, 104, 1 }, |
| |
| /* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */ |
| { S(512), 409, 307, 206, 102, 2 }, |
| /* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */ |
| { S(512), 409, 309, 205, 103, 2 }, |
| |
| /* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */ |
| { S(256), 205, 155, 101, 52, 1 }, |
| |
| /* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */ |
| { S(128), 103, 78, 51, 27, 2 }, |
| |
| /* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */ |
| { S(64), 52, 39, 26, 14, 1 }, |
| #endif |
| }; |
| |
| /* |
| * Static global variables |
| */ |
| static DECLARE_WAIT_QUEUE_HEAD(random_read_wait); |
| static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); |
| static struct fasync_struct *fasync; |
| |
| static DEFINE_SPINLOCK(random_ready_list_lock); |
| static LIST_HEAD(random_ready_list); |
| |
| struct crng_state { |
| __u32 state[16]; |
| unsigned long init_time; |
| spinlock_t lock; |
| }; |
| |
| struct crng_state primary_crng = { |
| .lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock), |
| }; |
| |
| /* |
| * crng_init = 0 --> Uninitialized |
| * 1 --> Initialized |
| * 2 --> Initialized from input_pool |
| * |
| * crng_init is protected by primary_crng->lock, and only increases |
| * its value (from 0->1->2). |
| */ |
| static int crng_init = 0; |
| #define crng_ready() (likely(crng_init > 1)) |
| static int crng_init_cnt = 0; |
| static unsigned long crng_global_init_time = 0; |
| #define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE) |
| static void _extract_crng(struct crng_state *crng, |
| __u32 out[CHACHA20_BLOCK_WORDS]); |
| static void _crng_backtrack_protect(struct crng_state *crng, |
| __u32 tmp[CHACHA20_BLOCK_WORDS], int used); |
| static void process_random_ready_list(void); |
| static void _get_random_bytes(void *buf, int nbytes); |
| |
| static struct ratelimit_state unseeded_warning = |
| RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3); |
| static struct ratelimit_state urandom_warning = |
| RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3); |
| |
| static int ratelimit_disable __read_mostly; |
| |
| module_param_named(ratelimit_disable, ratelimit_disable, int, 0644); |
| MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression"); |
| |
| /********************************************************************** |
| * |
| * OS independent entropy store. Here are the functions which handle |
| * storing entropy in an entropy pool. |
| * |
| **********************************************************************/ |
| |
| struct entropy_store; |
| struct entropy_store { |
| /* read-only data: */ |
| const struct poolinfo *poolinfo; |
| __u32 *pool; |
| const char *name; |
| struct entropy_store *pull; |
| struct work_struct push_work; |
| |
| /* read-write data: */ |
| unsigned long last_pulled; |
| spinlock_t lock; |
| unsigned short add_ptr; |
| unsigned short input_rotate; |
| int entropy_count; |
| int entropy_total; |
| unsigned int initialized:1; |
| unsigned int last_data_init:1; |
| __u8 last_data[EXTRACT_SIZE]; |
| }; |
| |
| static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
| size_t nbytes, int min, int rsvd); |
| static ssize_t _extract_entropy(struct entropy_store *r, void *buf, |
| size_t nbytes, int fips); |
| |
| static void crng_reseed(struct crng_state *crng, struct entropy_store *r); |
| static void push_to_pool(struct work_struct *work); |
| static __u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy; |
| static __u32 blocking_pool_data[OUTPUT_POOL_WORDS] __latent_entropy; |
| |
| static struct entropy_store input_pool = { |
| .poolinfo = &poolinfo_table[0], |
| .name = "input", |
| .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock), |
| .pool = input_pool_data |
| }; |
| |
| static struct entropy_store blocking_pool = { |
| .poolinfo = &poolinfo_table[1], |
| .name = "blocking", |
| .pull = &input_pool, |
| .lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock), |
| .pool = blocking_pool_data, |
| .push_work = __WORK_INITIALIZER(blocking_pool.push_work, |
| push_to_pool), |
| }; |
| |
| static __u32 const twist_table[8] = { |
| 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158, |
| 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 }; |
| |
| /* |
| * This function adds bytes into the entropy "pool". It does not |
| * update the entropy estimate. The caller should call |
| * credit_entropy_bits if this is appropriate. |
| * |
| * The pool is stirred with a primitive polynomial of the appropriate |
| * degree, and then twisted. We twist by three bits at a time because |
| * it's cheap to do so and helps slightly in the expected case where |
| * the entropy is concentrated in the low-order bits. |
| */ |
| static void _mix_pool_bytes(struct entropy_store *r, const void *in, |
| int nbytes) |
| { |
| unsigned long i, tap1, tap2, tap3, tap4, tap5; |
| int input_rotate; |
| int wordmask = r->poolinfo->poolwords - 1; |
| const char *bytes = in; |
| __u32 w; |
| |
| tap1 = r->poolinfo->tap1; |
| tap2 = r->poolinfo->tap2; |
| tap3 = r->poolinfo->tap3; |
| tap4 = r->poolinfo->tap4; |
| tap5 = r->poolinfo->tap5; |
| |
| input_rotate = r->input_rotate; |
| i = r->add_ptr; |
| |
| /* mix one byte at a time to simplify size handling and churn faster */ |
| while (nbytes--) { |
| w = rol32(*bytes++, input_rotate); |
| i = (i - 1) & wordmask; |
| |
| /* XOR in the various taps */ |
| w ^= r->pool[i]; |
| w ^= r->pool[(i + tap1) & wordmask]; |
| w ^= r->pool[(i + tap2) & wordmask]; |
| w ^= r->pool[(i + tap3) & wordmask]; |
| w ^= r->pool[(i + tap4) & wordmask]; |
| w ^= r->pool[(i + tap5) & wordmask]; |
| |
| /* Mix the result back in with a twist */ |
| r->pool[i] = (w >> 3) ^ twist_table[w & 7]; |
| |
| /* |
| * Normally, we add 7 bits of rotation to the pool. |
| * At the beginning of the pool, add an extra 7 bits |
| * rotation, so that successive passes spread the |
| * input bits across the pool evenly. |
| */ |
| input_rotate = (input_rotate + (i ? 7 : 14)) & 31; |
| } |
| |
| r->input_rotate = input_rotate; |
| r->add_ptr = i; |
| } |
| |
| static void __mix_pool_bytes(struct entropy_store *r, const void *in, |
| int nbytes) |
| { |
| trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_); |
| _mix_pool_bytes(r, in, nbytes); |
| } |
| |
| static void mix_pool_bytes(struct entropy_store *r, const void *in, |
| int nbytes) |
| { |
| unsigned long flags; |
| |
| trace_mix_pool_bytes(r->name, nbytes, _RET_IP_); |
| spin_lock_irqsave(&r->lock, flags); |
| _mix_pool_bytes(r, in, nbytes); |
| spin_unlock_irqrestore(&r->lock, flags); |
| } |
| |
| struct fast_pool { |
| __u32 pool[4]; |
| unsigned long last; |
| unsigned short reg_idx; |
| unsigned char count; |
| }; |
| |
| /* |
| * This is a fast mixing routine used by the interrupt randomness |
| * collector. It's hardcoded for an 128 bit pool and assumes that any |
| * locks that might be needed are taken by the caller. |
| */ |
| static void fast_mix(struct fast_pool *f) |
| { |
| __u32 a = f->pool[0], b = f->pool[1]; |
| __u32 c = f->pool[2], d = f->pool[3]; |
| |
| a += b; c += d; |
| b = rol32(b, 6); d = rol32(d, 27); |
| d ^= a; b ^= c; |
| |
| a += b; c += d; |
| b = rol32(b, 16); d = rol32(d, 14); |
| d ^= a; b ^= c; |
| |
| a += b; c += d; |
| b = rol32(b, 6); d = rol32(d, 27); |
| d ^= a; b ^= c; |
| |
| a += b; c += d; |
| b = rol32(b, 16); d = rol32(d, 14); |
| d ^= a; b ^= c; |
| |
| f->pool[0] = a; f->pool[1] = b; |
| f->pool[2] = c; f->pool[3] = d; |
| f->count++; |
| } |
| |
| static void process_random_ready_list(void) |
| { |
| unsigned long flags; |
| struct random_ready_callback *rdy, *tmp; |
| |
| spin_lock_irqsave(&random_ready_list_lock, flags); |
| list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) { |
| struct module *owner = rdy->owner; |
| |
| list_del_init(&rdy->list); |
| rdy->func(rdy); |
| module_put(owner); |
| } |
| spin_unlock_irqrestore(&random_ready_list_lock, flags); |
| } |
| |
| /* |
| * Credit (or debit) the entropy store with n bits of entropy. |
| * Use credit_entropy_bits_safe() if the value comes from userspace |
| * or otherwise should be checked for extreme values. |
| */ |
| static void credit_entropy_bits(struct entropy_store *r, int nbits) |
| { |
| int entropy_count, orig; |
| const int pool_size = r->poolinfo->poolfracbits; |
| int nfrac = nbits << ENTROPY_SHIFT; |
| |
| if (!nbits) |
| return; |
| |
| retry: |
| entropy_count = orig = ACCESS_ONCE(r->entropy_count); |
| if (nfrac < 0) { |
| /* Debit */ |
| entropy_count += nfrac; |
| } else { |
| /* |
| * Credit: we have to account for the possibility of |
| * overwriting already present entropy. Even in the |
| * ideal case of pure Shannon entropy, new contributions |
| * approach the full value asymptotically: |
| * |
| * entropy <- entropy + (pool_size - entropy) * |
| * (1 - exp(-add_entropy/pool_size)) |
| * |
| * For add_entropy <= pool_size/2 then |
| * (1 - exp(-add_entropy/pool_size)) >= |
| * (add_entropy/pool_size)*0.7869... |
| * so we can approximate the exponential with |
| * 3/4*add_entropy/pool_size and still be on the |
| * safe side by adding at most pool_size/2 at a time. |
| * |
| * The use of pool_size-2 in the while statement is to |
| * prevent rounding artifacts from making the loop |
| * arbitrarily long; this limits the loop to log2(pool_size)*2 |
| * turns no matter how large nbits is. |
| */ |
| int pnfrac = nfrac; |
| const int s = r->poolinfo->poolbitshift + ENTROPY_SHIFT + 2; |
| /* The +2 corresponds to the /4 in the denominator */ |
| |
| do { |
| unsigned int anfrac = min(pnfrac, pool_size/2); |
| unsigned int add = |
| ((pool_size - entropy_count)*anfrac*3) >> s; |
| |
| entropy_count += add; |
| pnfrac -= anfrac; |
| } while (unlikely(entropy_count < pool_size-2 && pnfrac)); |
| } |
| |
| if (unlikely(entropy_count < 0)) { |
| pr_warn("random: negative entropy/overflow: pool %s count %d\n", |
| r->name, entropy_count); |
| WARN_ON(1); |
| entropy_count = 0; |
| } else if (entropy_count > pool_size) |
| entropy_count = pool_size; |
| if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) |
| goto retry; |
| |
| r->entropy_total += nbits; |
| if (!r->initialized && r->entropy_total > 128) { |
| r->initialized = 1; |
| r->entropy_total = 0; |
| } |
| |
| trace_credit_entropy_bits(r->name, nbits, |
| entropy_count >> ENTROPY_SHIFT, |
| r->entropy_total, _RET_IP_); |
| |
| if (r == &input_pool) { |
| int entropy_bits = entropy_count >> ENTROPY_SHIFT; |
| |
| if (crng_init < 2 && entropy_bits >= 128) { |
| crng_reseed(&primary_crng, r); |
| entropy_bits = r->entropy_count >> ENTROPY_SHIFT; |
| } |
| |
| /* should we wake readers? */ |
| if (entropy_bits >= random_read_wakeup_bits && |
| wq_has_sleeper(&random_read_wait)) { |
| wake_up_interruptible(&random_read_wait); |
| kill_fasync(&fasync, SIGIO, POLL_IN); |
| } |
| /* If the input pool is getting full, send some |
| * entropy to the blocking pool until it is 75% full. |
| */ |
| if (entropy_bits > random_write_wakeup_bits && |
| r->initialized && |
| r->entropy_total >= 2*random_read_wakeup_bits) { |
| struct entropy_store *other = &blocking_pool; |
| |
| if (other->entropy_count <= |
| 3 * other->poolinfo->poolfracbits / 4) { |
| schedule_work(&other->push_work); |
| r->entropy_total = 0; |
| } |
| } |
| } |
| } |
| |
| static int credit_entropy_bits_safe(struct entropy_store *r, int nbits) |
| { |
| const int nbits_max = r->poolinfo->poolwords * 32; |
| |
| if (nbits < 0) |
| return -EINVAL; |
| |
| /* Cap the value to avoid overflows */ |
| nbits = min(nbits, nbits_max); |
| |
| credit_entropy_bits(r, nbits); |
| return 0; |
| } |
| |
| /********************************************************************* |
| * |
| * CRNG using CHACHA20 |
| * |
| *********************************************************************/ |
| |
| #define CRNG_RESEED_INTERVAL (300*HZ) |
| |
| static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); |
| |
| #ifdef CONFIG_NUMA |
| /* |
| * Hack to deal with crazy userspace progams when they are all trying |
| * to access /dev/urandom in parallel. The programs are almost |
| * certainly doing something terribly wrong, but we'll work around |
| * their brain damage. |
| */ |
| static struct crng_state **crng_node_pool __read_mostly; |
| #endif |
| |
| static void invalidate_batched_entropy(void); |
| |
| static void crng_initialize(struct crng_state *crng) |
| { |
| int i; |
| unsigned long rv; |
| |
| memcpy(&crng->state[0], "expand 32-byte k", 16); |
| if (crng == &primary_crng) |
| _extract_entropy(&input_pool, &crng->state[4], |
| sizeof(__u32) * 12, 0); |
| else |
| _get_random_bytes(&crng->state[4], sizeof(__u32) * 12); |
| for (i = 4; i < 16; i++) { |
| if (!arch_get_random_seed_long(&rv) && |
| !arch_get_random_long(&rv)) |
| rv = random_get_entropy(); |
| crng->state[i] ^= rv; |
| } |
| crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1; |
| } |
| |
| #ifdef CONFIG_NUMA |
| static void do_numa_crng_init(struct work_struct *work) |
| { |
| int i; |
| struct crng_state *crng; |
| struct crng_state **pool; |
| |
| pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL); |
| for_each_online_node(i) { |
| crng = kmalloc_node(sizeof(struct crng_state), |
| GFP_KERNEL | __GFP_NOFAIL, i); |
| spin_lock_init(&crng->lock); |
| crng_initialize(crng); |
| pool[i] = crng; |
| } |
| /* pairs with READ_ONCE() in select_crng() */ |
| if (cmpxchg_release(&crng_node_pool, NULL, pool) != NULL) { |
| for_each_node(i) |
| kfree(pool[i]); |
| kfree(pool); |
| } |
| } |
| |
| static DECLARE_WORK(numa_crng_init_work, do_numa_crng_init); |
| |
| static void numa_crng_init(void) |
| { |
| schedule_work(&numa_crng_init_work); |
| } |
| |
| static struct crng_state *select_crng(void) |
| { |
| struct crng_state **pool; |
| int nid = numa_node_id(); |
| |
| /* pairs with cmpxchg_release() in do_numa_crng_init() */ |
| pool = READ_ONCE(crng_node_pool); |
| if (pool && pool[nid]) |
| return pool[nid]; |
| |
| return &primary_crng; |
| } |
| #else |
| static void numa_crng_init(void) {} |
| |
| static struct crng_state *select_crng(void) |
| { |
| return &primary_crng; |
| } |
| #endif |
| |
| /* |
| * crng_fast_load() can be called by code in the interrupt service |
| * path. So we can't afford to dilly-dally. |
| */ |
| static int crng_fast_load(const char *cp, size_t len) |
| { |
| unsigned long flags; |
| char *p; |
| |
| if (!spin_trylock_irqsave(&primary_crng.lock, flags)) |
| return 0; |
| if (crng_init != 0) { |
| spin_unlock_irqrestore(&primary_crng.lock, flags); |
| return 0; |
| } |
| p = (unsigned char *) &primary_crng.state[4]; |
| while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) { |
| p[crng_init_cnt % CHACHA20_KEY_SIZE] ^= *cp; |
| cp++; crng_init_cnt++; len--; |
| } |
| spin_unlock_irqrestore(&primary_crng.lock, flags); |
| if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) { |
| invalidate_batched_entropy(); |
| crng_init = 1; |
| wake_up_interruptible(&crng_init_wait); |
| pr_notice("random: fast init done\n"); |
| } |
| return 1; |
| } |
| |
| #ifdef CONFIG_NUMA |
| static void do_numa_crng_init(struct work_struct *work) |
| { |
| int i; |
| struct crng_state *crng; |
| struct crng_state **pool; |
| |
| pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL); |
| for_each_online_node(i) { |
| crng = kmalloc_node(sizeof(struct crng_state), |
| GFP_KERNEL | __GFP_NOFAIL, i); |
| spin_lock_init(&crng->lock); |
| crng_initialize(crng); |
| pool[i] = crng; |
| } |
| /* pairs with READ_ONCE() in select_crng() */ |
| if (cmpxchg_release(&crng_node_pool, NULL, pool) != NULL) { |
| for_each_node(i) |
| kfree(pool[i]); |
| kfree(pool); |
| } |
| } |
| |
| static DECLARE_WORK(numa_crng_init_work, do_numa_crng_init); |
| |
| static void numa_crng_init(void) |
| { |
| schedule_work(&numa_crng_init_work); |
| } |
| |
| static struct crng_state *select_crng(void) |
| { |
| struct crng_state **pool; |
| int nid = numa_node_id(); |
| |
| /* pairs with cmpxchg_release() in do_numa_crng_init() */ |
| pool = READ_ONCE(crng_node_pool); |
| if (pool && pool[nid]) |
| return pool[nid]; |
| |
| return &primary_crng; |
| } |
| #else |
| static void numa_crng_init(void) {} |
| |
| static struct crng_state *select_crng(void) |
| { |
| return &primary_crng; |
| } |
| #endif |
| |
| /* |
| * crng_slow_load() is called by add_device_randomness, which has two |
| * attributes. (1) We can't trust the buffer passed to it is |
| * guaranteed to be unpredictable (so it might not have any entropy at |
| * all), and (2) it doesn't have the performance constraints of |
| * crng_fast_load(). |
| * |
| * So we do something more comprehensive which is guaranteed to touch |
| * all of the primary_crng's state, and which uses a LFSR with a |
| * period of 255 as part of the mixing algorithm. Finally, we do |
| * *not* advance crng_init_cnt since buffer we may get may be something |
| * like a fixed DMI table (for example), which might very well be |
| * unique to the machine, but is otherwise unvarying. |
| */ |
| static int crng_slow_load(const char *cp, size_t len) |
| { |
| unsigned long flags; |
| static unsigned char lfsr = 1; |
| unsigned char tmp; |
| unsigned i, max = CHACHA20_KEY_SIZE; |
| const char * src_buf = cp; |
| char * dest_buf = (char *) &primary_crng.state[4]; |
| |
| if (!spin_trylock_irqsave(&primary_crng.lock, flags)) |
| return 0; |
| if (crng_init != 0) { |
| spin_unlock_irqrestore(&primary_crng.lock, flags); |
| return 0; |
| } |
| if (len > max) |
| max = len; |
| |
| for (i = 0; i < max ; i++) { |
| tmp = lfsr; |
| lfsr >>= 1; |
| if (tmp & 1) |
| lfsr ^= 0xE1; |
| tmp = dest_buf[i % CHACHA20_KEY_SIZE]; |
| dest_buf[i % CHACHA20_KEY_SIZE] ^= src_buf[i % len] ^ lfsr; |
| lfsr += (tmp << 3) | (tmp >> 5); |
| } |
| spin_unlock_irqrestore(&primary_crng.lock, flags); |
| return 1; |
| } |
| |
| static void crng_reseed(struct crng_state *crng, struct entropy_store *r) |
| { |
| unsigned long flags; |
| int i, num; |
| union { |
| __u32 block[CHACHA20_BLOCK_WORDS]; |
| __u32 key[8]; |
| } buf; |
| |
| if (r) { |
| num = extract_entropy(r, &buf, 32, 16, 0); |
| if (num == 0) |
| return; |
| } else { |
| _extract_crng(&primary_crng, buf.block); |
| _crng_backtrack_protect(&primary_crng, buf.block, |
| CHACHA20_KEY_SIZE); |
| } |
| spin_lock_irqsave(&crng->lock, flags); |
| for (i = 0; i < 8; i++) { |
| unsigned long rv; |
| if (!arch_get_random_seed_long(&rv) && |
| !arch_get_random_long(&rv)) |
| rv = random_get_entropy(); |
| crng->state[i+4] ^= buf.key[i] ^ rv; |
| } |
| memzero_explicit(&buf, sizeof(buf)); |
| WRITE_ONCE(crng->init_time, jiffies); |
| spin_unlock_irqrestore(&crng->lock, flags); |
| if (crng == &primary_crng && crng_init < 2) { |
| numa_crng_init(); |
| invalidate_batched_entropy(); |
| numa_crng_init(); |
| crng_init = 2; |
| process_random_ready_list(); |
| wake_up_interruptible(&crng_init_wait); |
| pr_notice("random: crng init done\n"); |
| if (unseeded_warning.missed) { |
| pr_notice("random: %d get_random_xx warning(s) missed " |
| "due to ratelimiting\n", |
| unseeded_warning.missed); |
| unseeded_warning.missed = 0; |
| } |
| if (urandom_warning.missed) { |
| pr_notice("random: %d urandom warning(s) missed " |
| "due to ratelimiting\n", |
| urandom_warning.missed); |
| urandom_warning.missed = 0; |
| } |
| } |
| } |
| |
| static void _extract_crng(struct crng_state *crng, |
| __u32 out[CHACHA20_BLOCK_WORDS]) |
| { |
| unsigned long v, flags, init_time; |
| |
| if (crng_ready()) { |
| init_time = READ_ONCE(crng->init_time); |
| if (time_after(READ_ONCE(crng_global_init_time), init_time) || |
| time_after(jiffies, init_time + CRNG_RESEED_INTERVAL)) |
| crng_reseed(crng, crng == &primary_crng ? |
| &input_pool : NULL); |
| } |
| spin_lock_irqsave(&crng->lock, flags); |
| if (arch_get_random_long(&v)) |
| crng->state[14] ^= v; |
| chacha20_block(&crng->state[0], out); |
| if (crng->state[12] == 0) |
| crng->state[13]++; |
| spin_unlock_irqrestore(&crng->lock, flags); |
| } |
| |
| static void extract_crng(__u32 out[CHACHA20_BLOCK_WORDS]) |
| { |
| _extract_crng(select_crng(), out); |
| } |
| |
| /* |
| * Use the leftover bytes from the CRNG block output (if there is |
| * enough) to mutate the CRNG key to provide backtracking protection. |
| */ |
| static void _crng_backtrack_protect(struct crng_state *crng, |
| __u32 tmp[CHACHA20_BLOCK_WORDS], int used) |
| { |
| unsigned long flags; |
| __u32 *s, *d; |
| int i; |
| |
| used = round_up(used, sizeof(__u32)); |
| if (used + CHACHA20_KEY_SIZE > CHACHA20_BLOCK_SIZE) { |
| extract_crng(tmp); |
| used = 0; |
| } |
| spin_lock_irqsave(&crng->lock, flags); |
| s = &tmp[used / sizeof(__u32)]; |
| d = &crng->state[4]; |
| for (i=0; i < 8; i++) |
| *d++ ^= *s++; |
| spin_unlock_irqrestore(&crng->lock, flags); |
| } |
| |
| static void crng_backtrack_protect(__u32 tmp[CHACHA20_BLOCK_WORDS], int used) |
| { |
| _crng_backtrack_protect(select_crng(), tmp, used); |
| } |
| |
| static ssize_t extract_crng_user(void __user *buf, size_t nbytes) |
| { |
| ssize_t ret = 0, i = CHACHA20_BLOCK_SIZE; |
| __u32 tmp[CHACHA20_BLOCK_WORDS]; |
| int large_request = (nbytes > 256); |
| |
| while (nbytes) { |
| if (large_request && need_resched()) { |
| if (signal_pending(current)) { |
| if (ret == 0) |
| ret = -ERESTARTSYS; |
| break; |
| } |
| schedule(); |
| } |
| |
| extract_crng(tmp); |
| i = min_t(int, nbytes, CHACHA20_BLOCK_SIZE); |
| if (copy_to_user(buf, tmp, i)) { |
| ret = -EFAULT; |
| break; |
| } |
| |
| nbytes -= i; |
| buf += i; |
| ret += i; |
| } |
| crng_backtrack_protect(tmp, i); |
| |
| /* Wipe data just written to memory */ |
| memzero_explicit(tmp, sizeof(tmp)); |
| |
| return ret; |
| } |
| |
| |
| /********************************************************************* |
| * |
| * Entropy input management |
| * |
| *********************************************************************/ |
| |
| /* There is one of these per entropy source */ |
| struct timer_rand_state { |
| cycles_t last_time; |
| long last_delta, last_delta2; |
| }; |
| |
| #define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, }; |
| |
| /* |
| * Add device- or boot-specific data to the input pool to help |
| * initialize it. |
| * |
| * None of this adds any entropy; it is meant to avoid the problem of |
| * the entropy pool having similar initial state across largely |
| * identical devices. |
| */ |
| void add_device_randomness(const void *buf, unsigned int size) |
| { |
| unsigned long time = random_get_entropy() ^ jiffies; |
| unsigned long flags; |
| |
| if (!crng_ready() && size) |
| crng_slow_load(buf, size); |
| |
| trace_add_device_randomness(size, _RET_IP_); |
| spin_lock_irqsave(&input_pool.lock, flags); |
| _mix_pool_bytes(&input_pool, buf, size); |
| _mix_pool_bytes(&input_pool, &time, sizeof(time)); |
| spin_unlock_irqrestore(&input_pool.lock, flags); |
| } |
| EXPORT_SYMBOL(add_device_randomness); |
| |
| static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE; |
| |
| /* |
| * This function adds entropy to the entropy "pool" by using timing |
| * delays. It uses the timer_rand_state structure to make an estimate |
| * of how many bits of entropy this call has added to the pool. |
| * |
| * The number "num" is also added to the pool - it should somehow describe |
| * the type of event which just happened. This is currently 0-255 for |
| * keyboard scan codes, and 256 upwards for interrupts. |
| * |
| */ |
| static void add_timer_randomness(struct timer_rand_state *state, unsigned num) |
| { |
| struct entropy_store *r; |
| struct { |
| long jiffies; |
| unsigned cycles; |
| unsigned num; |
| } sample; |
| long delta, delta2, delta3; |
| |
| preempt_disable(); |
| |
| sample.jiffies = jiffies; |
| sample.cycles = random_get_entropy(); |
| sample.num = num; |
| r = &input_pool; |
| mix_pool_bytes(r, &sample, sizeof(sample)); |
| |
| /* |
| * Calculate number of bits of randomness we probably added. |
| * We take into account the first, second and third-order deltas |
| * in order to make our estimate. |
| */ |
| delta = sample.jiffies - state->last_time; |
| state->last_time = sample.jiffies; |
| |
| delta2 = delta - state->last_delta; |
| state->last_delta = delta; |
| |
| delta3 = delta2 - state->last_delta2; |
| state->last_delta2 = delta2; |
| |
| if (delta < 0) |
| delta = -delta; |
| if (delta2 < 0) |
| delta2 = -delta2; |
| if (delta3 < 0) |
| delta3 = -delta3; |
| if (delta > delta2) |
| delta = delta2; |
| if (delta > delta3) |
| delta = delta3; |
| |
| /* |
| * delta is now minimum absolute delta. |
| * Round down by 1 bit on general principles, |
| * and limit entropy entimate to 12 bits. |
| */ |
| credit_entropy_bits(r, min_t(int, fls(delta>>1), 11)); |
| |
| preempt_enable(); |
| } |
| |
| void add_input_randomness(unsigned int type, unsigned int code, |
| unsigned int value) |
| { |
| static unsigned char last_value; |
| |
| /* ignore autorepeat and the like */ |
| if (value == last_value) |
| return; |
| |
| last_value = value; |
| add_timer_randomness(&input_timer_state, |
| (type << 4) ^ code ^ (code >> 4) ^ value); |
| trace_add_input_randomness(ENTROPY_BITS(&input_pool)); |
| } |
| EXPORT_SYMBOL_GPL(add_input_randomness); |
| |
| static DEFINE_PER_CPU(struct fast_pool, irq_randomness); |
| |
| #ifdef ADD_INTERRUPT_BENCH |
| static unsigned long avg_cycles, avg_deviation; |
| |
| #define AVG_SHIFT 8 /* Exponential average factor k=1/256 */ |
| #define FIXED_1_2 (1 << (AVG_SHIFT-1)) |
| |
| static void add_interrupt_bench(cycles_t start) |
| { |
| long delta = random_get_entropy() - start; |
| |
| /* Use a weighted moving average */ |
| delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT); |
| avg_cycles += delta; |
| /* And average deviation */ |
| delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT); |
| avg_deviation += delta; |
| } |
| #else |
| #define add_interrupt_bench(x) |
| #endif |
| |
| static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs) |
| { |
| __u32 *ptr = (__u32 *) regs; |
| unsigned int idx; |
| |
| if (regs == NULL) |
| return 0; |
| idx = READ_ONCE(f->reg_idx); |
| if (idx >= sizeof(struct pt_regs) / sizeof(__u32)) |
| idx = 0; |
| ptr += idx++; |
| WRITE_ONCE(f->reg_idx, idx); |
| return *ptr; |
| } |
| |
| void add_interrupt_randomness(int irq, int irq_flags) |
| { |
| struct entropy_store *r; |
| struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness); |
| struct pt_regs *regs = get_irq_regs(); |
| unsigned long now = jiffies; |
| cycles_t cycles = random_get_entropy(); |
| __u32 c_high, j_high; |
| __u64 ip; |
| unsigned long seed; |
| int credit = 0; |
| |
| if (cycles == 0) |
| cycles = get_reg(fast_pool, regs); |
| c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0; |
| j_high = (sizeof(now) > 4) ? now >> 32 : 0; |
| fast_pool->pool[0] ^= cycles ^ j_high ^ irq; |
| fast_pool->pool[1] ^= now ^ c_high; |
| ip = regs ? instruction_pointer(regs) : _RET_IP_; |
| fast_pool->pool[2] ^= ip; |
| fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 : |
| get_reg(fast_pool, regs); |
| |
| fast_mix(fast_pool); |
| add_interrupt_bench(cycles); |
| |
| if (unlikely(crng_init == 0)) { |
| if ((fast_pool->count >= 64) && |
| crng_fast_load((char *) fast_pool->pool, |
| sizeof(fast_pool->pool))) { |
| fast_pool->count = 0; |
| fast_pool->last = now; |
| } |
| return; |
| } |
| |
| if ((fast_pool->count < 64) && |
| !time_after(now, fast_pool->last + HZ)) |
| return; |
| |
| r = &input_pool; |
| if (!spin_trylock(&r->lock)) |
| return; |
| |
| fast_pool->last = now; |
| __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool)); |
| |
| /* |
| * If we have architectural seed generator, produce a seed and |
| * add it to the pool. For the sake of paranoia don't let the |
| * architectural seed generator dominate the input from the |
| * interrupt noise. |
| */ |
| if (arch_get_random_seed_long(&seed)) { |
| __mix_pool_bytes(r, &seed, sizeof(seed)); |
| credit = 1; |
| } |
| spin_unlock(&r->lock); |
| |
| fast_pool->count = 0; |
| |
| /* award one bit for the contents of the fast pool */ |
| credit_entropy_bits(r, credit + 1); |
| } |
| EXPORT_SYMBOL_GPL(add_interrupt_randomness); |
| |
| #ifdef CONFIG_BLOCK |
| void add_disk_randomness(struct gendisk *disk) |
| { |
| if (!disk || !disk->random) |
| return; |
| /* first major is 1, so we get >= 0x200 here */ |
| add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); |
| trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS(&input_pool)); |
| } |
| EXPORT_SYMBOL_GPL(add_disk_randomness); |
| #endif |
| |
| /********************************************************************* |
| * |
| * Entropy extraction routines |
| * |
| *********************************************************************/ |
| |
| /* |
| * This utility inline function is responsible for transferring entropy |
| * from the primary pool to the secondary extraction pool. We make |
| * sure we pull enough for a 'catastrophic reseed'. |
| */ |
| static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes); |
| static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes) |
| { |
| if (!r->pull || |
| r->entropy_count >= (nbytes << (ENTROPY_SHIFT + 3)) || |
| r->entropy_count > r->poolinfo->poolfracbits) |
| return; |
| |
| _xfer_secondary_pool(r, nbytes); |
| } |
| |
| static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes) |
| { |
| __u32 tmp[OUTPUT_POOL_WORDS]; |
| |
| int bytes = nbytes; |
| |
| /* pull at least as much as a wakeup */ |
| bytes = max_t(int, bytes, random_read_wakeup_bits / 8); |
| /* but never more than the buffer size */ |
| bytes = min_t(int, bytes, sizeof(tmp)); |
| |
| trace_xfer_secondary_pool(r->name, bytes * 8, nbytes * 8, |
| ENTROPY_BITS(r), ENTROPY_BITS(r->pull)); |
| bytes = extract_entropy(r->pull, tmp, bytes, |
| random_read_wakeup_bits / 8, 0); |
| mix_pool_bytes(r, tmp, bytes); |
| credit_entropy_bits(r, bytes*8); |
| } |
| |
| /* |
| * Used as a workqueue function so that when the input pool is getting |
| * full, we can "spill over" some entropy to the output pools. That |
| * way the output pools can store some of the excess entropy instead |
| * of letting it go to waste. |
| */ |
| static void push_to_pool(struct work_struct *work) |
| { |
| struct entropy_store *r = container_of(work, struct entropy_store, |
| push_work); |
| BUG_ON(!r); |
| _xfer_secondary_pool(r, random_read_wakeup_bits/8); |
| trace_push_to_pool(r->name, r->entropy_count >> ENTROPY_SHIFT, |
| r->pull->entropy_count >> ENTROPY_SHIFT); |
| } |
| |
| /* |
| * This function decides how many bytes to actually take from the |
| * given pool, and also debits the entropy count accordingly. |
| */ |
| static size_t account(struct entropy_store *r, size_t nbytes, int min, |
| int reserved) |
| { |
| int entropy_count, orig, have_bytes; |
| size_t ibytes, nfrac; |
| |
| BUG_ON(r->entropy_count > r->poolinfo->poolfracbits); |
| |
| /* Can we pull enough? */ |
| retry: |
| entropy_count = orig = ACCESS_ONCE(r->entropy_count); |
| ibytes = nbytes; |
| /* never pull more than available */ |
| have_bytes = entropy_count >> (ENTROPY_SHIFT + 3); |
| |
| if ((have_bytes -= reserved) < 0) |
| have_bytes = 0; |
| ibytes = min_t(size_t, ibytes, have_bytes); |
| if (ibytes < min) |
| ibytes = 0; |
| |
| if (unlikely(entropy_count < 0)) { |
| pr_warn("random: negative entropy count: pool %s count %d\n", |
| r->name, entropy_count); |
| WARN_ON(1); |
| entropy_count = 0; |
| } |
| nfrac = ibytes << (ENTROPY_SHIFT + 3); |
| if ((size_t) entropy_count > nfrac) |
| entropy_count -= nfrac; |
| else |
| entropy_count = 0; |
| |
| if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) |
| goto retry; |
| |
| trace_debit_entropy(r->name, 8 * ibytes); |
| if (ibytes && |
| (r->entropy_count >> ENTROPY_SHIFT) < random_write_wakeup_bits) { |
| wake_up_interruptible(&random_write_wait); |
| kill_fasync(&fasync, SIGIO, POLL_OUT); |
| } |
| |
| return ibytes; |
| } |
| |
| /* |
| * This function does the actual extraction for extract_entropy and |
| * extract_entropy_user. |
| * |
| * Note: we assume that .poolwords is a multiple of 16 words. |
| */ |
| static void extract_buf(struct entropy_store *r, __u8 *out) |
| { |
| int i; |
| union { |
| __u32 w[5]; |
| unsigned long l[LONGS(20)]; |
| } hash; |
| __u32 workspace[SHA_WORKSPACE_WORDS]; |
| unsigned long flags; |
| |
| /* |
| * If we have an architectural hardware random number |
| * generator, use it for SHA's initial vector |
| */ |
| sha_init(hash.w); |
| for (i = 0; i < LONGS(20); i++) { |
| unsigned long v; |
| if (!arch_get_random_long(&v)) |
| break; |
| hash.l[i] = v; |
| } |
| |
| /* Generate a hash across the pool, 16 words (512 bits) at a time */ |
| spin_lock_irqsave(&r->lock, flags); |
| for (i = 0; i < r->poolinfo->poolwords; i += 16) |
| sha_transform(hash.w, (__u8 *)(r->pool + i), workspace); |
| |
| /* |
| * We mix the hash back into the pool to prevent backtracking |
| * attacks (where the attacker knows the state of the pool |
| * plus the current outputs, and attempts to find previous |
| * ouputs), unless the hash function can be inverted. By |
| * mixing at least a SHA1 worth of hash data back, we make |
| * brute-forcing the feedback as hard as brute-forcing the |
| * hash. |
| */ |
| __mix_pool_bytes(r, hash.w, sizeof(hash.w)); |
| spin_unlock_irqrestore(&r->lock, flags); |
| |
| memzero_explicit(workspace, sizeof(workspace)); |
| |
| /* |
| * In case the hash function has some recognizable output |
| * pattern, we fold it in half. Thus, we always feed back |
| * twice as much data as we output. |
| */ |
| hash.w[0] ^= hash.w[3]; |
| hash.w[1] ^= hash.w[4]; |
| hash.w[2] ^= rol32(hash.w[2], 16); |
| |
| memcpy(out, &hash, EXTRACT_SIZE); |
| memzero_explicit(&hash, sizeof(hash)); |
| } |
| |
| static ssize_t _extract_entropy(struct entropy_store *r, void *buf, |
| size_t nbytes, int fips) |
| { |
| ssize_t ret = 0, i; |
| __u8 tmp[EXTRACT_SIZE]; |
| unsigned long flags; |
| |
| while (nbytes) { |
| extract_buf(r, tmp); |
| |
| if (fips) { |
| spin_lock_irqsave(&r->lock, flags); |
| if (!memcmp(tmp, r->last_data, EXTRACT_SIZE)) |
| panic("Hardware RNG duplicated output!\n"); |
| memcpy(r->last_data, tmp, EXTRACT_SIZE); |
| spin_unlock_irqrestore(&r->lock, flags); |
| } |
| i = min_t(int, nbytes, EXTRACT_SIZE); |
| memcpy(buf, tmp, i); |
| nbytes -= i; |
| buf += i; |
| ret += i; |
| } |
| |
| /* Wipe data just returned from memory */ |
| memzero_explicit(tmp, sizeof(tmp)); |
| |
| return ret; |
| } |
| |
| /* |
| * This function extracts randomness from the "entropy pool", and |
| * returns it in a buffer. |
| * |
| * The min parameter specifies the minimum amount we can pull before |
| * failing to avoid races that defeat catastrophic reseeding while the |
| * reserved parameter indicates how much entropy we must leave in the |
| * pool after each pull to avoid starving other readers. |
| */ |
| static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
| size_t nbytes, int min, int reserved) |
| { |
| __u8 tmp[EXTRACT_SIZE]; |
| unsigned long flags; |
| |
| /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */ |
| if (fips_enabled) { |
| spin_lock_irqsave(&r->lock, flags); |
| if (!r->last_data_init) { |
| r->last_data_init = 1; |
| spin_unlock_irqrestore(&r->lock, flags); |
| trace_extract_entropy(r->name, EXTRACT_SIZE, |
| ENTROPY_BITS(r), _RET_IP_); |
| xfer_secondary_pool(r, EXTRACT_SIZE); |
| extract_buf(r, tmp); |
| spin_lock_irqsave(&r->lock, flags); |
| memcpy(r->last_data, tmp, EXTRACT_SIZE); |
| } |
| spin_unlock_irqrestore(&r->lock, flags); |
| } |
| |
| trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_); |
| xfer_secondary_pool(r, nbytes); |
| nbytes = account(r, nbytes, min, reserved); |
| |
| return _extract_entropy(r, buf, nbytes, fips_enabled); |
| } |
| |
| /* |
| * This function extracts randomness from the "entropy pool", and |
| * returns it in a userspace buffer. |
| */ |
| static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf, |
| size_t nbytes) |
| { |
| ssize_t ret = 0, i; |
| __u8 tmp[EXTRACT_SIZE]; |
| int large_request = (nbytes > 256); |
| |
| trace_extract_entropy_user(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_); |
| xfer_secondary_pool(r, nbytes); |
| nbytes = account(r, nbytes, 0, 0); |
| |
| while (nbytes) { |
| if (large_request && need_resched()) { |
| if (signal_pending(current)) { |
| if (ret == 0) |
| ret = -ERESTARTSYS; |
| break; |
| } |
| schedule(); |
| } |
| |
| extract_buf(r, tmp); |
| i = min_t(int, nbytes, EXTRACT_SIZE); |
| if (copy_to_user(buf, tmp, i)) { |
| ret = -EFAULT; |
| break; |
| } |
| |
| nbytes -= i; |
| buf += i; |
| ret += i; |
| } |
| |
| /* Wipe data just returned from memory */ |
| memzero_explicit(tmp, sizeof(tmp)); |
| |
| return ret; |
| } |
| |
| #define warn_unseeded_randomness(previous) \ |
| _warn_unseeded_randomness(__func__, (void *) _RET_IP_, (previous)) |
| |
| static void _warn_unseeded_randomness(const char *func_name, void *caller, |
| void **previous) |
| { |
| #ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM |
| const bool print_once = false; |
| #else |
| static bool print_once __read_mostly; |
| #endif |
| |
| if (print_once || |
| crng_ready() || |
| (previous && (caller == READ_ONCE(*previous)))) |
| return; |
| WRITE_ONCE(*previous, caller); |
| #ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM |
| print_once = true; |
| #endif |
| if (__ratelimit(&unseeded_warning)) |
| pr_notice("random: %s called from %pS with crng_init=%d\n", |
| func_name, caller, crng_init); |
| } |
| |
| /* |
| * This function is the exported kernel interface. It returns some |
| * number of good random numbers, suitable for key generation, seeding |
| * TCP sequence numbers, etc. It does not rely on the hardware random |
| * number generator. For random bytes direct from the hardware RNG |
| * (when available), use get_random_bytes_arch(). In order to ensure |
| * that the randomness provided by this function is okay, the function |
| * wait_for_random_bytes() should be called and return 0 at least once |
| * at any point prior. |
| */ |
| static void _get_random_bytes(void *buf, int nbytes) |
| { |
| __u32 tmp[CHACHA20_BLOCK_WORDS]; |
| |
| trace_get_random_bytes(nbytes, _RET_IP_); |
| |
| while (nbytes >= CHACHA20_BLOCK_SIZE) { |
| extract_crng(buf); |
| buf += CHACHA20_BLOCK_SIZE; |
| nbytes -= CHACHA20_BLOCK_SIZE; |
| } |
| |
| if (nbytes > 0) { |
| extract_crng(tmp); |
| memcpy(buf, tmp, nbytes); |
| crng_backtrack_protect(tmp, nbytes); |
| } else |
| crng_backtrack_protect(tmp, CHACHA20_BLOCK_SIZE); |
| memzero_explicit(tmp, sizeof(tmp)); |
| } |
| |
| void get_random_bytes(void *buf, int nbytes) |
| { |
| static void *previous; |
| |
| warn_unseeded_randomness(&previous); |
| _get_random_bytes(buf, nbytes); |
| } |
| EXPORT_SYMBOL(get_random_bytes); |
| |
| /* |
| * Wait for the urandom pool to be seeded and thus guaranteed to supply |
| * cryptographically secure random numbers. This applies to: the /dev/urandom |
| * device, the get_random_bytes function, and the get_random_{u32,u64,int,long} |
| * family of functions. Using any of these functions without first calling |
| * this function forfeits the guarantee of security. |
| * |
| * Returns: 0 if the urandom pool has been seeded. |
| * -ERESTARTSYS if the function was interrupted by a signal. |
| */ |
| int wait_for_random_bytes(void) |
| { |
| if (likely(crng_ready())) |
| return 0; |
| return wait_event_interruptible(crng_init_wait, crng_ready()); |
| } |
| EXPORT_SYMBOL(wait_for_random_bytes); |
| |
| /* |
| * Add a callback function that will be invoked when the nonblocking |
| * pool is initialised. |
| * |
| * returns: 0 if callback is successfully added |
| * -EALREADY if pool is already initialised (callback not called) |
| * -ENOENT if module for callback is not alive |
| */ |
| int add_random_ready_callback(struct random_ready_callback *rdy) |
| { |
| struct module *owner; |
| unsigned long flags; |
| int err = -EALREADY; |
| |
| if (crng_ready()) |
| return err; |
| |
| owner = rdy->owner; |
| if (!try_module_get(owner)) |
| return -ENOENT; |
| |
| spin_lock_irqsave(&random_ready_list_lock, flags); |
| if (crng_ready()) |
| goto out; |
| |
| owner = NULL; |
| |
| list_add(&rdy->list, &random_ready_list); |
| err = 0; |
| |
| out: |
| spin_unlock_irqrestore(&random_ready_list_lock, flags); |
| |
| module_put(owner); |
| |
| return err; |
| } |
| EXPORT_SYMBOL(add_random_ready_callback); |
| |
| /* |
| * Delete a previously registered readiness callback function. |
| */ |
| void del_random_ready_callback(struct random_ready_callback *rdy) |
| { |
| unsigned long flags; |
| struct module *owner = NULL; |
| |
| spin_lock_irqsave(&random_ready_list_lock, flags); |
| if (!list_empty(&rdy->list)) { |
| list_del_init(&rdy->list); |
| owner = rdy->owner; |
| } |
| spin_unlock_irqrestore(&random_ready_list_lock, flags); |
| |
| module_put(owner); |
| } |
| EXPORT_SYMBOL(del_random_ready_callback); |
| |
| /* |
| * This function will use the architecture-specific hardware random |
| * number generator if it is available. The arch-specific hw RNG will |
| * almost certainly be faster than what we can do in software, but it |
| * is impossible to verify that it is implemented securely (as |
| * opposed, to, say, the AES encryption of a sequence number using a |
| * key known by the NSA). So it's useful if we need the speed, but |
| * only if we're willing to trust the hardware manufacturer not to |
| * have put in a back door. |
| */ |
| void get_random_bytes_arch(void *buf, int nbytes) |
| { |
| char *p = buf; |
| |
| trace_get_random_bytes_arch(nbytes, _RET_IP_); |
| while (nbytes) { |
| unsigned long v; |
| int chunk = min(nbytes, (int)sizeof(unsigned long)); |
| |
| if (!arch_get_random_long(&v)) |
| break; |
| |
| memcpy(p, &v, chunk); |
| p += chunk; |
| nbytes -= chunk; |
| } |
| |
| if (nbytes) |
| get_random_bytes(p, nbytes); |
| } |
| EXPORT_SYMBOL(get_random_bytes_arch); |
| |
| /* |
| * init_std_data - initialize pool with system data |
| * |
| * @r: pool to initialize |
| * |
| * This function clears the pool's entropy count and mixes some system |
| * data into the pool to prepare it for use. The pool is not cleared |
| * as that can only decrease the entropy in the pool. |
| */ |
| static void init_std_data(struct entropy_store *r) |
| { |
| int i; |
| ktime_t now = ktime_get_real(); |
| unsigned long rv; |
| |
| r->last_pulled = jiffies; |
| mix_pool_bytes(r, &now, sizeof(now)); |
| for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) { |
| if (!arch_get_random_seed_long(&rv) && |
| !arch_get_random_long(&rv)) |
| rv = random_get_entropy(); |
| mix_pool_bytes(r, &rv, sizeof(rv)); |
| } |
| mix_pool_bytes(r, utsname(), sizeof(*(utsname()))); |
| } |
| |
| /* |
| * Note that setup_arch() may call add_device_randomness() |
| * long before we get here. This allows seeding of the pools |
| * with some platform dependent data very early in the boot |
| * process. But it limits our options here. We must use |
| * statically allocated structures that already have all |
| * initializations complete at compile time. We should also |
| * take care not to overwrite the precious per platform data |
| * we were given. |
| */ |
| static int rand_initialize(void) |
| { |
| init_std_data(&input_pool); |
| init_std_data(&blocking_pool); |
| crng_initialize(&primary_crng); |
| crng_global_init_time = jiffies; |
| if (ratelimit_disable) { |
| urandom_warning.interval = 0; |
| unseeded_warning.interval = 0; |
| } |
| return 0; |
| } |
| early_initcall(rand_initialize); |
| |
| #ifdef CONFIG_BLOCK |
| void rand_initialize_disk(struct gendisk *disk) |
| { |
| struct timer_rand_state *state; |
| |
| /* |
| * If kzalloc returns null, we just won't use that entropy |
| * source. |
| */ |
| state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
| if (state) { |
| state->last_time = INITIAL_JIFFIES; |
| disk->random = state; |
| } |
| } |
| #endif |
| |
| static ssize_t |
| _random_read(int nonblock, char __user *buf, size_t nbytes) |
| { |
| ssize_t n; |
| |
| if (nbytes == 0) |
| return 0; |
| |
| nbytes = min_t(size_t, nbytes, SEC_XFER_SIZE); |
| while (1) { |
| n = extract_entropy_user(&blocking_pool, buf, nbytes); |
| if (n < 0) |
| return n; |
| trace_random_read(n*8, (nbytes-n)*8, |
| ENTROPY_BITS(&blocking_pool), |
| ENTROPY_BITS(&input_pool)); |
| if (n > 0) |
| return n; |
| |
| /* Pool is (near) empty. Maybe wait and retry. */ |
| if (nonblock) |
| return -EAGAIN; |
| |
| wait_event_interruptible(random_read_wait, |
| ENTROPY_BITS(&input_pool) >= |
| random_read_wakeup_bits); |
| if (signal_pending(current)) |
| return -ERESTARTSYS; |
| } |
| } |
| |
| static ssize_t |
| random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
| { |
| return _random_read(file->f_flags & O_NONBLOCK, buf, nbytes); |
| } |
| |
| static ssize_t |
| urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
| { |
| unsigned long flags; |
| static int maxwarn = 10; |
| int ret; |
| |
| if (!crng_ready() && maxwarn > 0) { |
| maxwarn--; |
| if (__ratelimit(&urandom_warning)) |
| printk(KERN_NOTICE "random: %s: uninitialized " |
| "urandom read (%zd bytes read)\n", |
| current->comm, nbytes); |
| spin_lock_irqsave(&primary_crng.lock, flags); |
| crng_init_cnt = 0; |
| spin_unlock_irqrestore(&primary_crng.lock, flags); |
| } |
| nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3)); |
| ret = extract_crng_user(buf, nbytes); |
| trace_urandom_read(8 * nbytes, 0, ENTROPY_BITS(&input_pool)); |
| return ret; |
| } |
| |
| static unsigned int |
| random_poll(struct file *file, poll_table * wait) |
| { |
| unsigned int mask; |
| |
| poll_wait(file, &random_read_wait, wait); |
| poll_wait(file, &random_write_wait, wait); |
| mask = 0; |
| if (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits) |
| mask |= POLLIN | POLLRDNORM; |
| if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits) |
| mask |= POLLOUT | POLLWRNORM; |
| return mask; |
| } |
| |
| static int |
| write_pool(struct entropy_store *r, const char __user *buffer, size_t count) |
| { |
| size_t bytes; |
| __u32 t, buf[16]; |
| const char __user *p = buffer; |
| |
| while (count > 0) { |
| int b, i = 0; |
| |
| bytes = min(count, sizeof(buf)); |
| if (copy_from_user(&buf, p, bytes)) |
| return -EFAULT; |
| |
| for (b = bytes ; b > 0 ; b -= sizeof(__u32), i++) { |
| if (!arch_get_random_int(&t)) |
| break; |
| buf[i] ^= t; |
| } |
| |
| count -= bytes; |
| p += bytes; |
| |
| mix_pool_bytes(r, buf, bytes); |
| cond_resched(); |
| } |
| |
| return 0; |
| } |
| |
| static ssize_t random_write(struct file *file, const char __user *buffer, |
| size_t count, loff_t *ppos) |
| { |
| size_t ret; |
| |
| ret = write_pool(&input_pool, buffer, count); |
| if (ret) |
| return ret; |
| |
| return (ssize_t)count; |
| } |
| |
| static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) |
| { |
| int size, ent_count; |
| int __user *p = (int __user *)arg; |
| int retval; |
| |
| switch (cmd) { |
| case RNDGETENTCNT: |
| /* inherently racy, no point locking */ |
| ent_count = ENTROPY_BITS(&input_pool); |
| if (put_user(ent_count, p)) |
| return -EFAULT; |
| return 0; |
| case RNDADDTOENTCNT: |
| if (!capable(CAP_SYS_ADMIN)) |
| return -EPERM; |
| if (get_user(ent_count, p)) |
| return -EFAULT; |
| return credit_entropy_bits_safe(&input_pool, ent_count); |
| case RNDADDENTROPY: |
| if (!capable(CAP_SYS_ADMIN)) |
| return -EPERM; |
| if (get_user(ent_count, p++)) |
| return -EFAULT; |
| if (ent_count < 0) |
| return -EINVAL; |
| if (get_user(size, p++)) |
| return -EFAULT; |
| retval = write_pool(&input_pool, (const char __user *)p, |
| size); |
| if (retval < 0) |
| return retval; |
| return credit_entropy_bits_safe(&input_pool, ent_count); |
| case RNDZAPENTCNT: |
| case RNDCLEARPOOL: |
| /* |
| * Clear the entropy pool counters. We no longer clear |
| * the entropy pool, as that's silly. |
| */ |
| if (!capable(CAP_SYS_ADMIN)) |
| return -EPERM; |
| input_pool.entropy_count = 0; |
| blocking_pool.entropy_count = 0; |
| return 0; |
| case RNDRESEEDCRNG: |
| if (!capable(CAP_SYS_ADMIN)) |
| return -EPERM; |
| if (crng_init < 2) |
| return -ENODATA; |
| crng_reseed(&primary_crng, &input_pool); |
| WRITE_ONCE(crng_global_init_time, jiffies - 1); |
| return 0; |
| default: |
| return -EINVAL; |
| } |
| } |
| |
| static int random_fasync(int fd, struct file *filp, int on) |
| { |
| return fasync_helper(fd, filp, on, &fasync); |
| } |
| |
| const struct file_operations random_fops = { |
| .read = random_read, |
| .write = random_write, |
| .poll = random_poll, |
| .unlocked_ioctl = random_ioctl, |
| .fasync = random_fasync, |
| .llseek = noop_llseek, |
| }; |
| |
| const struct file_operations urandom_fops = { |
| .read = urandom_read, |
| .write = random_write, |
| .unlocked_ioctl = random_ioctl, |
| .fasync = random_fasync, |
| .llseek = noop_llseek, |
| }; |
| |
| SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, |
| unsigned int, flags) |
| { |
| int ret; |
| |
| if (flags & ~(GRND_NONBLOCK|GRND_RANDOM)) |
| return -EINVAL; |
| |
| if (count > INT_MAX) |
| count = INT_MAX; |
| |
| if (flags & GRND_RANDOM) |
| return _random_read(flags & GRND_NONBLOCK, buf, count); |
| |
| if (!crng_ready()) { |
| if (flags & GRND_NONBLOCK) |
| return -EAGAIN; |
| ret = wait_for_random_bytes(); |
| if (unlikely(ret)) |
| return ret; |
| } |
| return urandom_read(NULL, buf, count, NULL); |
| } |
| |
| /******************************************************************** |
| * |
| * Sysctl interface |
| * |
| ********************************************************************/ |
| |
| #ifdef CONFIG_SYSCTL |
| |
| #include <linux/sysctl.h> |
| |
| static int min_read_thresh = 8, min_write_thresh; |
| static int max_read_thresh = OUTPUT_POOL_WORDS * 32; |
| static int max_write_thresh = INPUT_POOL_WORDS * 32; |
| static int random_min_urandom_seed = 60; |
| static char sysctl_bootid[16]; |
| |
| /* |
| * This function is used to return both the bootid UUID, and random |
| * UUID. The difference is in whether table->data is NULL; if it is, |
| * then a new UUID is generated and returned to the user. |
| * |
| * If the user accesses this via the proc interface, the UUID will be |
| * returned as an ASCII string in the standard UUID format; if via the |
| * sysctl system call, as 16 bytes of binary data. |
| */ |
| static int proc_do_uuid(struct ctl_table *table, int write, |
| void __user *buffer, size_t *lenp, loff_t *ppos) |
| { |
| struct ctl_table fake_table; |
| unsigned char buf[64], tmp_uuid[16], *uuid; |
| |
| uuid = table->data; |
| if (!uuid) { |
| uuid = tmp_uuid; |
| generate_random_uuid(uuid); |
| } else { |
| static DEFINE_SPINLOCK(bootid_spinlock); |
| |
| spin_lock(&bootid_spinlock); |
| if (!uuid[8]) |
| generate_random_uuid(uuid); |
| spin_unlock(&bootid_spinlock); |
| } |
| |
| sprintf(buf, "%pU", uuid); |
| |
| fake_table.data = buf; |
| fake_table.maxlen = sizeof(buf); |
| |
| return proc_dostring(&fake_table, write, buffer, lenp, ppos); |
| } |
| |
| /* |
| * Return entropy available scaled to integral bits |
| */ |
| static int proc_do_entropy(struct ctl_table *table, int write, |
| void __user *buffer, size_t *lenp, loff_t *ppos) |
| { |
| struct ctl_table fake_table; |
| int entropy_count; |
| |
| entropy_count = *(int *)table->data >> ENTROPY_SHIFT; |
| |
| fake_table.data = &entropy_count; |
| fake_table.maxlen = sizeof(entropy_count); |
| |
| return proc_dointvec(&fake_table, write, buffer, lenp, ppos); |
| } |
| |
| static int sysctl_poolsize = INPUT_POOL_WORDS * 32; |
| extern struct ctl_table random_table[]; |
| struct ctl_table random_table[] = { |
| { |
| .procname = "poolsize", |
| .data = &sysctl_poolsize, |
| .maxlen = sizeof(int), |
| .mode = 0444, |
| .proc_handler = proc_dointvec, |
| }, |
| { |
| .procname = "entropy_avail", |
| .maxlen = sizeof(int), |
| .mode = 0444, |
| .proc_handler = proc_do_entropy, |
| .data = &input_pool.entropy_count, |
| }, |
| { |
| .procname = "read_wakeup_threshold", |
| .data = &random_read_wakeup_bits, |
| .maxlen = sizeof(int), |
| .mode = 0644, |
| .proc_handler = proc_dointvec_minmax, |
| .extra1 = &min_read_thresh, |
| .extra2 = &max_read_thresh, |
| }, |
| { |
| .procname = "write_wakeup_threshold", |
| .data = &random_write_wakeup_bits, |
| .maxlen = sizeof(int), |
| .mode = 0644, |
| .proc_handler = proc_dointvec_minmax, |
| .extra1 = &min_write_thresh, |
| .extra2 = &max_write_thresh, |
| }, |
| { |
| .procname = "urandom_min_reseed_secs", |
| .data = &random_min_urandom_seed, |
| .maxlen = sizeof(int), |
| .mode = 0644, |
| .proc_handler = proc_dointvec, |
| }, |
| { |
| .procname = "boot_id", |
| .data = &sysctl_bootid, |
| .maxlen = 16, |
| .mode = 0444, |
| .proc_handler = proc_do_uuid, |
| }, |
| { |
| .procname = "uuid", |
| .maxlen = 16, |
| .mode = 0444, |
| .proc_handler = proc_do_uuid, |
| }, |
| #ifdef ADD_INTERRUPT_BENCH |
| { |
| .procname = "add_interrupt_avg_cycles", |
| .data = &avg_cycles, |
| .maxlen = sizeof(avg_cycles), |
| .mode = 0444, |
| .proc_handler = proc_doulongvec_minmax, |
| }, |
| { |
| .procname = "add_interrupt_avg_deviation", |
| .data = &avg_deviation, |
| .maxlen = sizeof(avg_deviation), |
| .mode = 0444, |
| .proc_handler = proc_doulongvec_minmax, |
| }, |
| #endif |
| { } |
| }; |
| #endif /* CONFIG_SYSCTL */ |
| |
| struct batched_entropy { |
| union { |
| u64 entropy_u64[CHACHA20_BLOCK_SIZE / sizeof(u64)]; |
| u32 entropy_u32[CHACHA20_BLOCK_SIZE / sizeof(u32)]; |
| }; |
| unsigned int position; |
| spinlock_t batch_lock; |
| }; |
| |
| /* |
| * Get a random word for internal kernel use only. The quality of the random |
| * number is good as /dev/urandom, but there is no backtrack protection, with |
| * the goal of being quite fast and not depleting entropy. In order to ensure |
| * that the randomness provided by this function is okay, the function |
| * wait_for_random_bytes() should be called and return 0 at least once at any |
| * point prior. |
| */ |
| static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = { |
| .batch_lock = __SPIN_LOCK_UNLOCKED(batched_entropy_u64.lock), |
| }; |
| |
| u64 get_random_u64(void) |
| { |
| u64 ret; |
| unsigned long flags; |
| struct batched_entropy *batch; |
| static void *previous; |
| |
| warn_unseeded_randomness(&previous); |
| |
| batch = raw_cpu_ptr(&batched_entropy_u64); |
| spin_lock_irqsave(&batch->batch_lock, flags); |
| if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) { |
| extract_crng((__u32 *)batch->entropy_u64); |
| batch->position = 0; |
| } |
| ret = batch->entropy_u64[batch->position++]; |
| spin_unlock_irqrestore(&batch->batch_lock, flags); |
| return ret; |
| } |
| EXPORT_SYMBOL(get_random_u64); |
| |
| static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = { |
| .batch_lock = __SPIN_LOCK_UNLOCKED(batched_entropy_u32.lock), |
| }; |
| u32 get_random_u32(void) |
| { |
| u32 ret; |
| unsigned long flags; |
| struct batched_entropy *batch; |
| static void *previous; |
| |
| warn_unseeded_randomness(&previous); |
| |
| batch = raw_cpu_ptr(&batched_entropy_u32); |
| spin_lock_irqsave(&batch->batch_lock, flags); |
| if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) { |
| extract_crng(batch->entropy_u32); |
| batch->position = 0; |
| } |
| ret = batch->entropy_u32[batch->position++]; |
| spin_unlock_irqrestore(&batch->batch_lock, flags); |
| return ret; |
| } |
| EXPORT_SYMBOL(get_random_u32); |
| |
| /* It's important to invalidate all potential batched entropy that might |
| * be stored before the crng is initialized, which we can do lazily by |
| * simply resetting the counter to zero so that it's re-extracted on the |
| * next usage. */ |
| static void invalidate_batched_entropy(void) |
| { |
| int cpu; |
| unsigned long flags; |
| |
| for_each_possible_cpu (cpu) { |
| struct batched_entropy *batched_entropy; |
| |
| batched_entropy = per_cpu_ptr(&batched_entropy_u32, cpu); |
| spin_lock_irqsave(&batched_entropy->batch_lock, flags); |
| batched_entropy->position = 0; |
| spin_unlock(&batched_entropy->batch_lock); |
| |
| batched_entropy = per_cpu_ptr(&batched_entropy_u64, cpu); |
| spin_lock(&batched_entropy->batch_lock); |
| batched_entropy->position = 0; |
| spin_unlock_irqrestore(&batched_entropy->batch_lock, flags); |
| } |
| } |
| |
| /** |
| * randomize_page - Generate a random, page aligned address |
| * @start: The smallest acceptable address the caller will take. |
| * @range: The size of the area, starting at @start, within which the |
| * random address must fall. |
| * |
| * If @start + @range would overflow, @range is capped. |
| * |
| * NOTE: Historical use of randomize_range, which this replaces, presumed that |
| * @start was already page aligned. We now align it regardless. |
| * |
| * Return: A page aligned address within [start, start + range). On error, |
| * @start is returned. |
| */ |
| unsigned long |
| randomize_page(unsigned long start, unsigned long range) |
| { |
| if (!PAGE_ALIGNED(start)) { |
| range -= PAGE_ALIGN(start) - start; |
| start = PAGE_ALIGN(start); |
| } |
| |
| if (start > ULONG_MAX - range) |
| range = ULONG_MAX - start; |
| |
| range >>= PAGE_SHIFT; |
| |
| if (range == 0) |
| return start; |
| |
| return start + (get_random_long() % range << PAGE_SHIFT); |
| } |
| |
| /* Interface for in-kernel drivers of true hardware RNGs. |
| * Those devices may produce endless random bits and will be throttled |
| * when our pool is full. |
| */ |
| void add_hwgenerator_randomness(const char *buffer, size_t count, |
| size_t entropy) |
| { |
| struct entropy_store *poolp = &input_pool; |
| |
| if (unlikely(crng_init == 0)) { |
| crng_fast_load(buffer, count); |
| return; |
| } |
| |
| /* Suspend writing if we're above the trickle threshold. |
| * We'll be woken up again once below random_write_wakeup_thresh, |
| * or when the calling thread is about to terminate. |
| */ |
| wait_event_interruptible(random_write_wait, kthread_should_stop() || |
| ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits); |
| mix_pool_bytes(poolp, buffer, count); |
| credit_entropy_bits(poolp, entropy); |
| } |
| EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); |