Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Linux Socket Filter - Kernel level socket filtering |
| 3 | * |
| 4 | * Author: |
| 5 | * Jay Schulist <jschlst@samba.org> |
| 6 | * |
| 7 | * Based on the design of: |
| 8 | * - The Berkeley Packet Filter |
| 9 | * |
| 10 | * This program is free software; you can redistribute it and/or |
| 11 | * modify it under the terms of the GNU General Public License |
| 12 | * as published by the Free Software Foundation; either version |
| 13 | * 2 of the License, or (at your option) any later version. |
| 14 | * |
| 15 | * Andi Kleen - Fix a few bad bugs and races. |
Kris Katterjohn | 9369986 | 2006-01-04 13:58:36 -0800 | [diff] [blame] | 16 | * Kris Katterjohn - Added many additional checks in sk_chk_filter() |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 17 | */ |
| 18 | |
| 19 | #include <linux/module.h> |
| 20 | #include <linux/types.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 21 | #include <linux/mm.h> |
| 22 | #include <linux/fcntl.h> |
| 23 | #include <linux/socket.h> |
| 24 | #include <linux/in.h> |
| 25 | #include <linux/inet.h> |
| 26 | #include <linux/netdevice.h> |
| 27 | #include <linux/if_packet.h> |
| 28 | #include <net/ip.h> |
| 29 | #include <net/protocol.h> |
Patrick McHardy | 4738c1d | 2008-04-10 02:02:28 -0700 | [diff] [blame] | 30 | #include <net/netlink.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 31 | #include <linux/skbuff.h> |
| 32 | #include <net/sock.h> |
| 33 | #include <linux/errno.h> |
| 34 | #include <linux/timer.h> |
| 35 | #include <asm/system.h> |
| 36 | #include <asm/uaccess.h> |
Dmitry Mishin | 40daafc | 2006-04-18 14:50:10 -0700 | [diff] [blame] | 37 | #include <asm/unaligned.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 38 | #include <linux/filter.h> |
| 39 | |
| 40 | /* No hurry in this branch */ |
Patrick McHardy | 0b05b2a | 2005-07-05 14:10:21 -0700 | [diff] [blame] | 41 | static void *__load_pointer(struct sk_buff *skb, int k) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 42 | { |
| 43 | u8 *ptr = NULL; |
| 44 | |
| 45 | if (k >= SKF_NET_OFF) |
Arnaldo Carvalho de Melo | d56f90a | 2007-04-10 20:50:43 -0700 | [diff] [blame] | 46 | ptr = skb_network_header(skb) + k - SKF_NET_OFF; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 47 | else if (k >= SKF_LL_OFF) |
Arnaldo Carvalho de Melo | 98e399f | 2007-03-19 15:33:04 -0700 | [diff] [blame] | 48 | ptr = skb_mac_header(skb) + k - SKF_LL_OFF; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 49 | |
Arnaldo Carvalho de Melo | 27a884d | 2007-04-19 20:29:13 -0700 | [diff] [blame] | 50 | if (ptr >= skb->head && ptr < skb_tail_pointer(skb)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 51 | return ptr; |
| 52 | return NULL; |
| 53 | } |
| 54 | |
Patrick McHardy | 0b05b2a | 2005-07-05 14:10:21 -0700 | [diff] [blame] | 55 | static inline void *load_pointer(struct sk_buff *skb, int k, |
YOSHIFUJI Hideaki | 4ec93ed | 2007-02-09 23:24:36 +0900 | [diff] [blame] | 56 | unsigned int size, void *buffer) |
Patrick McHardy | 0b05b2a | 2005-07-05 14:10:21 -0700 | [diff] [blame] | 57 | { |
| 58 | if (k >= 0) |
| 59 | return skb_header_pointer(skb, k, size, buffer); |
| 60 | else { |
| 61 | if (k >= SKF_AD_OFF) |
| 62 | return NULL; |
| 63 | return __load_pointer(skb, k); |
| 64 | } |
| 65 | } |
| 66 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 67 | /** |
Stephen Hemminger | 43db6d6 | 2008-04-10 01:43:09 -0700 | [diff] [blame] | 68 | * sk_filter - run a packet through a socket filter |
| 69 | * @sk: sock associated with &sk_buff |
| 70 | * @skb: buffer to filter |
Stephen Hemminger | 43db6d6 | 2008-04-10 01:43:09 -0700 | [diff] [blame] | 71 | * |
| 72 | * Run the filter code and then cut skb->data to correct size returned by |
| 73 | * sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller |
| 74 | * than pkt_len we keep whole skb->data. This is the socket level |
| 75 | * wrapper to sk_run_filter. It returns 0 if the packet should |
| 76 | * be accepted or -EPERM if the packet should be tossed. |
| 77 | * |
| 78 | */ |
| 79 | int sk_filter(struct sock *sk, struct sk_buff *skb) |
| 80 | { |
| 81 | int err; |
| 82 | struct sk_filter *filter; |
| 83 | |
| 84 | err = security_sock_rcv_skb(sk, skb); |
| 85 | if (err) |
| 86 | return err; |
| 87 | |
| 88 | rcu_read_lock_bh(); |
Paul E. McKenney | a898def | 2010-02-22 17:04:49 -0800 | [diff] [blame] | 89 | filter = rcu_dereference_bh(sk->sk_filter); |
Stephen Hemminger | 43db6d6 | 2008-04-10 01:43:09 -0700 | [diff] [blame] | 90 | if (filter) { |
| 91 | unsigned int pkt_len = sk_run_filter(skb, filter->insns, |
| 92 | filter->len); |
| 93 | err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM; |
| 94 | } |
| 95 | rcu_read_unlock_bh(); |
| 96 | |
| 97 | return err; |
| 98 | } |
| 99 | EXPORT_SYMBOL(sk_filter); |
| 100 | |
| 101 | /** |
Kris Katterjohn | 2966b66 | 2006-01-23 16:26:16 -0800 | [diff] [blame] | 102 | * sk_run_filter - run a filter on a socket |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 103 | * @skb: buffer to run the filter on |
| 104 | * @filter: filter to apply |
| 105 | * @flen: length of filter |
| 106 | * |
| 107 | * Decode and apply filter instructions to the skb->data. |
| 108 | * Return length to keep, 0 for none. skb is the data we are |
| 109 | * filtering, filter is the array of filter instructions, and |
| 110 | * len is the number of filter blocks in the array. |
| 111 | */ |
Kris Katterjohn | 4bad4dc | 2006-01-06 13:08:20 -0800 | [diff] [blame] | 112 | unsigned int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 113 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 114 | struct sock_filter *fentry; /* We walk down these */ |
Patrick McHardy | 0b05b2a | 2005-07-05 14:10:21 -0700 | [diff] [blame] | 115 | void *ptr; |
Kris Katterjohn | 2966b66 | 2006-01-23 16:26:16 -0800 | [diff] [blame] | 116 | u32 A = 0; /* Accumulator */ |
| 117 | u32 X = 0; /* Index Register */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 118 | u32 mem[BPF_MEMWORDS]; /* Scratch Memory Store */ |
Patrick McHardy | 0b05b2a | 2005-07-05 14:10:21 -0700 | [diff] [blame] | 119 | u32 tmp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 120 | int k; |
| 121 | int pc; |
| 122 | |
| 123 | /* |
| 124 | * Process array of filter instructions. |
| 125 | */ |
| 126 | for (pc = 0; pc < flen; pc++) { |
| 127 | fentry = &filter[pc]; |
YOSHIFUJI Hideaki | 4ec93ed | 2007-02-09 23:24:36 +0900 | [diff] [blame] | 128 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 129 | switch (fentry->code) { |
| 130 | case BPF_ALU|BPF_ADD|BPF_X: |
| 131 | A += X; |
| 132 | continue; |
| 133 | case BPF_ALU|BPF_ADD|BPF_K: |
| 134 | A += fentry->k; |
| 135 | continue; |
| 136 | case BPF_ALU|BPF_SUB|BPF_X: |
| 137 | A -= X; |
| 138 | continue; |
| 139 | case BPF_ALU|BPF_SUB|BPF_K: |
| 140 | A -= fentry->k; |
| 141 | continue; |
| 142 | case BPF_ALU|BPF_MUL|BPF_X: |
| 143 | A *= X; |
| 144 | continue; |
| 145 | case BPF_ALU|BPF_MUL|BPF_K: |
| 146 | A *= fentry->k; |
| 147 | continue; |
| 148 | case BPF_ALU|BPF_DIV|BPF_X: |
| 149 | if (X == 0) |
| 150 | return 0; |
| 151 | A /= X; |
| 152 | continue; |
| 153 | case BPF_ALU|BPF_DIV|BPF_K: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 154 | A /= fentry->k; |
| 155 | continue; |
| 156 | case BPF_ALU|BPF_AND|BPF_X: |
| 157 | A &= X; |
| 158 | continue; |
| 159 | case BPF_ALU|BPF_AND|BPF_K: |
| 160 | A &= fentry->k; |
| 161 | continue; |
| 162 | case BPF_ALU|BPF_OR|BPF_X: |
| 163 | A |= X; |
| 164 | continue; |
| 165 | case BPF_ALU|BPF_OR|BPF_K: |
| 166 | A |= fentry->k; |
| 167 | continue; |
| 168 | case BPF_ALU|BPF_LSH|BPF_X: |
| 169 | A <<= X; |
| 170 | continue; |
| 171 | case BPF_ALU|BPF_LSH|BPF_K: |
| 172 | A <<= fentry->k; |
| 173 | continue; |
| 174 | case BPF_ALU|BPF_RSH|BPF_X: |
| 175 | A >>= X; |
| 176 | continue; |
| 177 | case BPF_ALU|BPF_RSH|BPF_K: |
| 178 | A >>= fentry->k; |
| 179 | continue; |
| 180 | case BPF_ALU|BPF_NEG: |
| 181 | A = -A; |
| 182 | continue; |
| 183 | case BPF_JMP|BPF_JA: |
| 184 | pc += fentry->k; |
| 185 | continue; |
| 186 | case BPF_JMP|BPF_JGT|BPF_K: |
| 187 | pc += (A > fentry->k) ? fentry->jt : fentry->jf; |
| 188 | continue; |
| 189 | case BPF_JMP|BPF_JGE|BPF_K: |
| 190 | pc += (A >= fentry->k) ? fentry->jt : fentry->jf; |
| 191 | continue; |
| 192 | case BPF_JMP|BPF_JEQ|BPF_K: |
| 193 | pc += (A == fentry->k) ? fentry->jt : fentry->jf; |
| 194 | continue; |
| 195 | case BPF_JMP|BPF_JSET|BPF_K: |
| 196 | pc += (A & fentry->k) ? fentry->jt : fentry->jf; |
| 197 | continue; |
| 198 | case BPF_JMP|BPF_JGT|BPF_X: |
| 199 | pc += (A > X) ? fentry->jt : fentry->jf; |
| 200 | continue; |
| 201 | case BPF_JMP|BPF_JGE|BPF_X: |
| 202 | pc += (A >= X) ? fentry->jt : fentry->jf; |
| 203 | continue; |
| 204 | case BPF_JMP|BPF_JEQ|BPF_X: |
| 205 | pc += (A == X) ? fentry->jt : fentry->jf; |
| 206 | continue; |
| 207 | case BPF_JMP|BPF_JSET|BPF_X: |
| 208 | pc += (A & X) ? fentry->jt : fentry->jf; |
| 209 | continue; |
| 210 | case BPF_LD|BPF_W|BPF_ABS: |
| 211 | k = fentry->k; |
Kris Katterjohn | e35bedf | 2006-01-17 02:25:52 -0800 | [diff] [blame] | 212 | load_w: |
Patrick McHardy | 0b05b2a | 2005-07-05 14:10:21 -0700 | [diff] [blame] | 213 | ptr = load_pointer(skb, k, 4, &tmp); |
| 214 | if (ptr != NULL) { |
Harvey Harrison | d3e2ce3 | 2008-05-02 16:26:16 -0700 | [diff] [blame] | 215 | A = get_unaligned_be32(ptr); |
Patrick McHardy | 0b05b2a | 2005-07-05 14:10:21 -0700 | [diff] [blame] | 216 | continue; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 217 | } |
Herbert Xu | 1198ad0 | 2005-09-05 18:44:37 -0700 | [diff] [blame] | 218 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 219 | case BPF_LD|BPF_H|BPF_ABS: |
| 220 | k = fentry->k; |
Kris Katterjohn | e35bedf | 2006-01-17 02:25:52 -0800 | [diff] [blame] | 221 | load_h: |
Patrick McHardy | 0b05b2a | 2005-07-05 14:10:21 -0700 | [diff] [blame] | 222 | ptr = load_pointer(skb, k, 2, &tmp); |
| 223 | if (ptr != NULL) { |
Harvey Harrison | d3e2ce3 | 2008-05-02 16:26:16 -0700 | [diff] [blame] | 224 | A = get_unaligned_be16(ptr); |
Patrick McHardy | 0b05b2a | 2005-07-05 14:10:21 -0700 | [diff] [blame] | 225 | continue; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 226 | } |
Herbert Xu | 1198ad0 | 2005-09-05 18:44:37 -0700 | [diff] [blame] | 227 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 228 | case BPF_LD|BPF_B|BPF_ABS: |
| 229 | k = fentry->k; |
| 230 | load_b: |
Patrick McHardy | 0b05b2a | 2005-07-05 14:10:21 -0700 | [diff] [blame] | 231 | ptr = load_pointer(skb, k, 1, &tmp); |
| 232 | if (ptr != NULL) { |
| 233 | A = *(u8 *)ptr; |
| 234 | continue; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 235 | } |
Herbert Xu | 1198ad0 | 2005-09-05 18:44:37 -0700 | [diff] [blame] | 236 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 237 | case BPF_LD|BPF_W|BPF_LEN: |
Patrick McHardy | 3154e54 | 2005-07-05 14:10:40 -0700 | [diff] [blame] | 238 | A = skb->len; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 239 | continue; |
| 240 | case BPF_LDX|BPF_W|BPF_LEN: |
Patrick McHardy | 3154e54 | 2005-07-05 14:10:40 -0700 | [diff] [blame] | 241 | X = skb->len; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 242 | continue; |
| 243 | case BPF_LD|BPF_W|BPF_IND: |
| 244 | k = X + fentry->k; |
| 245 | goto load_w; |
| 246 | case BPF_LD|BPF_H|BPF_IND: |
| 247 | k = X + fentry->k; |
| 248 | goto load_h; |
| 249 | case BPF_LD|BPF_B|BPF_IND: |
| 250 | k = X + fentry->k; |
| 251 | goto load_b; |
| 252 | case BPF_LDX|BPF_B|BPF_MSH: |
Patrick McHardy | 0b05b2a | 2005-07-05 14:10:21 -0700 | [diff] [blame] | 253 | ptr = load_pointer(skb, fentry->k, 1, &tmp); |
| 254 | if (ptr != NULL) { |
| 255 | X = (*(u8 *)ptr & 0xf) << 2; |
| 256 | continue; |
| 257 | } |
| 258 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 259 | case BPF_LD|BPF_IMM: |
| 260 | A = fentry->k; |
| 261 | continue; |
| 262 | case BPF_LDX|BPF_IMM: |
| 263 | X = fentry->k; |
| 264 | continue; |
| 265 | case BPF_LD|BPF_MEM: |
| 266 | A = mem[fentry->k]; |
| 267 | continue; |
| 268 | case BPF_LDX|BPF_MEM: |
| 269 | X = mem[fentry->k]; |
| 270 | continue; |
| 271 | case BPF_MISC|BPF_TAX: |
| 272 | X = A; |
| 273 | continue; |
| 274 | case BPF_MISC|BPF_TXA: |
| 275 | A = X; |
| 276 | continue; |
| 277 | case BPF_RET|BPF_K: |
Kris Katterjohn | 4bad4dc | 2006-01-06 13:08:20 -0800 | [diff] [blame] | 278 | return fentry->k; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 279 | case BPF_RET|BPF_A: |
Kris Katterjohn | 4bad4dc | 2006-01-06 13:08:20 -0800 | [diff] [blame] | 280 | return A; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 281 | case BPF_ST: |
| 282 | mem[fentry->k] = A; |
| 283 | continue; |
| 284 | case BPF_STX: |
| 285 | mem[fentry->k] = X; |
| 286 | continue; |
| 287 | default: |
Kris Katterjohn | 9369986 | 2006-01-04 13:58:36 -0800 | [diff] [blame] | 288 | WARN_ON(1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 289 | return 0; |
| 290 | } |
| 291 | |
| 292 | /* |
| 293 | * Handle ancillary data, which are impossible |
| 294 | * (or very difficult) to get parsing packet contents. |
| 295 | */ |
| 296 | switch (k-SKF_AD_OFF) { |
| 297 | case SKF_AD_PROTOCOL: |
Al Viro | 252e334 | 2006-11-14 20:48:11 -0800 | [diff] [blame] | 298 | A = ntohs(skb->protocol); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 299 | continue; |
| 300 | case SKF_AD_PKTTYPE: |
| 301 | A = skb->pkt_type; |
| 302 | continue; |
| 303 | case SKF_AD_IFINDEX: |
| 304 | A = skb->dev->ifindex; |
| 305 | continue; |
jamal | 7e75f93 | 2009-10-19 02:17:56 +0000 | [diff] [blame] | 306 | case SKF_AD_MARK: |
| 307 | A = skb->mark; |
| 308 | continue; |
Eric Dumazet | d19742f | 2009-10-20 01:06:22 -0700 | [diff] [blame] | 309 | case SKF_AD_QUEUE: |
| 310 | A = skb->queue_mapping; |
| 311 | continue; |
Patrick McHardy | 4738c1d | 2008-04-10 02:02:28 -0700 | [diff] [blame] | 312 | case SKF_AD_NLATTR: { |
| 313 | struct nlattr *nla; |
| 314 | |
| 315 | if (skb_is_nonlinear(skb)) |
| 316 | return 0; |
| 317 | if (A > skb->len - sizeof(struct nlattr)) |
| 318 | return 0; |
| 319 | |
| 320 | nla = nla_find((struct nlattr *)&skb->data[A], |
| 321 | skb->len - A, X); |
| 322 | if (nla) |
| 323 | A = (void *)nla - (void *)skb->data; |
| 324 | else |
| 325 | A = 0; |
| 326 | continue; |
| 327 | } |
Pablo Neira Ayuso | d214c75 | 2008-11-20 00:49:27 -0800 | [diff] [blame] | 328 | case SKF_AD_NLATTR_NEST: { |
| 329 | struct nlattr *nla; |
| 330 | |
| 331 | if (skb_is_nonlinear(skb)) |
| 332 | return 0; |
| 333 | if (A > skb->len - sizeof(struct nlattr)) |
| 334 | return 0; |
| 335 | |
| 336 | nla = (struct nlattr *)&skb->data[A]; |
| 337 | if (nla->nla_len > A - skb->len) |
| 338 | return 0; |
| 339 | |
| 340 | nla = nla_find_nested(nla, X); |
| 341 | if (nla) |
| 342 | A = (void *)nla - (void *)skb->data; |
| 343 | else |
| 344 | A = 0; |
| 345 | continue; |
| 346 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 347 | default: |
| 348 | return 0; |
| 349 | } |
| 350 | } |
| 351 | |
| 352 | return 0; |
| 353 | } |
Stephen Hemminger | b715631 | 2008-04-10 01:33:47 -0700 | [diff] [blame] | 354 | EXPORT_SYMBOL(sk_run_filter); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 355 | |
| 356 | /** |
| 357 | * sk_chk_filter - verify socket filter code |
| 358 | * @filter: filter to verify |
| 359 | * @flen: length of filter |
| 360 | * |
| 361 | * Check the user's filter code. If we let some ugly |
| 362 | * filter code slip through kaboom! The filter must contain |
Kris Katterjohn | 9369986 | 2006-01-04 13:58:36 -0800 | [diff] [blame] | 363 | * no references or jumps that are out of range, no illegal |
| 364 | * instructions, and must end with a RET instruction. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 365 | * |
Kris Katterjohn | 7b11f69 | 2006-01-13 14:33:06 -0800 | [diff] [blame] | 366 | * All jumps are forward as they are not signed. |
| 367 | * |
| 368 | * Returns 0 if the rule set is legal or -EINVAL if not. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 369 | */ |
| 370 | int sk_chk_filter(struct sock_filter *filter, int flen) |
| 371 | { |
| 372 | struct sock_filter *ftest; |
| 373 | int pc; |
| 374 | |
David S. Miller | 1b93ae64 | 2005-12-27 13:57:59 -0800 | [diff] [blame] | 375 | if (flen == 0 || flen > BPF_MAXINSNS) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 376 | return -EINVAL; |
| 377 | |
| 378 | /* check the filter code now */ |
| 379 | for (pc = 0; pc < flen; pc++) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 380 | ftest = &filter[pc]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 381 | |
Kris Katterjohn | 9369986 | 2006-01-04 13:58:36 -0800 | [diff] [blame] | 382 | /* Only allow valid instructions */ |
| 383 | switch (ftest->code) { |
| 384 | case BPF_ALU|BPF_ADD|BPF_K: |
| 385 | case BPF_ALU|BPF_ADD|BPF_X: |
| 386 | case BPF_ALU|BPF_SUB|BPF_K: |
| 387 | case BPF_ALU|BPF_SUB|BPF_X: |
| 388 | case BPF_ALU|BPF_MUL|BPF_K: |
| 389 | case BPF_ALU|BPF_MUL|BPF_X: |
| 390 | case BPF_ALU|BPF_DIV|BPF_X: |
| 391 | case BPF_ALU|BPF_AND|BPF_K: |
| 392 | case BPF_ALU|BPF_AND|BPF_X: |
| 393 | case BPF_ALU|BPF_OR|BPF_K: |
| 394 | case BPF_ALU|BPF_OR|BPF_X: |
| 395 | case BPF_ALU|BPF_LSH|BPF_K: |
| 396 | case BPF_ALU|BPF_LSH|BPF_X: |
| 397 | case BPF_ALU|BPF_RSH|BPF_K: |
| 398 | case BPF_ALU|BPF_RSH|BPF_X: |
| 399 | case BPF_ALU|BPF_NEG: |
| 400 | case BPF_LD|BPF_W|BPF_ABS: |
| 401 | case BPF_LD|BPF_H|BPF_ABS: |
| 402 | case BPF_LD|BPF_B|BPF_ABS: |
| 403 | case BPF_LD|BPF_W|BPF_LEN: |
| 404 | case BPF_LD|BPF_W|BPF_IND: |
| 405 | case BPF_LD|BPF_H|BPF_IND: |
| 406 | case BPF_LD|BPF_B|BPF_IND: |
| 407 | case BPF_LD|BPF_IMM: |
| 408 | case BPF_LDX|BPF_W|BPF_LEN: |
| 409 | case BPF_LDX|BPF_B|BPF_MSH: |
| 410 | case BPF_LDX|BPF_IMM: |
| 411 | case BPF_MISC|BPF_TAX: |
| 412 | case BPF_MISC|BPF_TXA: |
| 413 | case BPF_RET|BPF_K: |
| 414 | case BPF_RET|BPF_A: |
| 415 | break; |
Kris Katterjohn | fb0d366 | 2005-11-20 13:41:34 -0800 | [diff] [blame] | 416 | |
Kris Katterjohn | 9369986 | 2006-01-04 13:58:36 -0800 | [diff] [blame] | 417 | /* Some instructions need special checks */ |
| 418 | |
| 419 | case BPF_ALU|BPF_DIV|BPF_K: |
| 420 | /* check for division by zero */ |
| 421 | if (ftest->k == 0) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 422 | return -EINVAL; |
Kris Katterjohn | 9369986 | 2006-01-04 13:58:36 -0800 | [diff] [blame] | 423 | break; |
| 424 | |
| 425 | case BPF_LD|BPF_MEM: |
| 426 | case BPF_LDX|BPF_MEM: |
| 427 | case BPF_ST: |
| 428 | case BPF_STX: |
| 429 | /* check for invalid memory addresses */ |
| 430 | if (ftest->k >= BPF_MEMWORDS) |
| 431 | return -EINVAL; |
| 432 | break; |
| 433 | |
| 434 | case BPF_JMP|BPF_JA: |
| 435 | /* |
| 436 | * Note, the large ftest->k might cause loops. |
| 437 | * Compare this with conditional jumps below, |
| 438 | * where offsets are limited. --ANK (981016) |
| 439 | */ |
| 440 | if (ftest->k >= (unsigned)(flen-pc-1)) |
| 441 | return -EINVAL; |
| 442 | break; |
| 443 | |
| 444 | case BPF_JMP|BPF_JEQ|BPF_K: |
| 445 | case BPF_JMP|BPF_JEQ|BPF_X: |
| 446 | case BPF_JMP|BPF_JGE|BPF_K: |
| 447 | case BPF_JMP|BPF_JGE|BPF_X: |
| 448 | case BPF_JMP|BPF_JGT|BPF_K: |
| 449 | case BPF_JMP|BPF_JGT|BPF_X: |
| 450 | case BPF_JMP|BPF_JSET|BPF_K: |
| 451 | case BPF_JMP|BPF_JSET|BPF_X: |
| 452 | /* for conditionals both must be safe */ |
Kris Katterjohn | e35bedf | 2006-01-17 02:25:52 -0800 | [diff] [blame] | 453 | if (pc + ftest->jt + 1 >= flen || |
Kris Katterjohn | 9369986 | 2006-01-04 13:58:36 -0800 | [diff] [blame] | 454 | pc + ftest->jf + 1 >= flen) |
| 455 | return -EINVAL; |
| 456 | break; |
| 457 | |
| 458 | default: |
| 459 | return -EINVAL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 460 | } |
| 461 | } |
| 462 | |
Kris Katterjohn | e35bedf | 2006-01-17 02:25:52 -0800 | [diff] [blame] | 463 | return (BPF_CLASS(filter[flen - 1].code) == BPF_RET) ? 0 : -EINVAL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 464 | } |
Stephen Hemminger | b715631 | 2008-04-10 01:33:47 -0700 | [diff] [blame] | 465 | EXPORT_SYMBOL(sk_chk_filter); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 466 | |
| 467 | /** |
Pavel Emelyanov | 47e958e | 2007-10-17 21:22:42 -0700 | [diff] [blame] | 468 | * sk_filter_rcu_release: Release a socket filter by rcu_head |
| 469 | * @rcu: rcu_head that contains the sk_filter to free |
| 470 | */ |
| 471 | static void sk_filter_rcu_release(struct rcu_head *rcu) |
| 472 | { |
| 473 | struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu); |
| 474 | |
| 475 | sk_filter_release(fp); |
| 476 | } |
| 477 | |
| 478 | static void sk_filter_delayed_uncharge(struct sock *sk, struct sk_filter *fp) |
| 479 | { |
| 480 | unsigned int size = sk_filter_len(fp); |
| 481 | |
| 482 | atomic_sub(size, &sk->sk_omem_alloc); |
| 483 | call_rcu_bh(&fp->rcu, sk_filter_rcu_release); |
| 484 | } |
| 485 | |
| 486 | /** |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 487 | * sk_attach_filter - attach a socket filter |
| 488 | * @fprog: the filter program |
| 489 | * @sk: the socket to use |
| 490 | * |
| 491 | * Attach the user's filter code. We first run some sanity checks on |
| 492 | * it to make sure it does not explode on us later. If an error |
| 493 | * occurs or there is insufficient memory for the filter a negative |
| 494 | * errno code is returned. On success the return is zero. |
| 495 | */ |
| 496 | int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) |
| 497 | { |
Pavel Emelyanov | d3904b7 | 2007-10-17 21:22:17 -0700 | [diff] [blame] | 498 | struct sk_filter *fp, *old_fp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 499 | unsigned int fsize = sizeof(struct sock_filter) * fprog->len; |
| 500 | int err; |
| 501 | |
| 502 | /* Make sure new filter is there and in the right amounts. */ |
Kris Katterjohn | e35bedf | 2006-01-17 02:25:52 -0800 | [diff] [blame] | 503 | if (fprog->filter == NULL) |
| 504 | return -EINVAL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 505 | |
| 506 | fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL); |
| 507 | if (!fp) |
| 508 | return -ENOMEM; |
| 509 | if (copy_from_user(fp->insns, fprog->filter, fsize)) { |
YOSHIFUJI Hideaki | 4ec93ed | 2007-02-09 23:24:36 +0900 | [diff] [blame] | 510 | sock_kfree_s(sk, fp, fsize+sizeof(*fp)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 511 | return -EFAULT; |
| 512 | } |
| 513 | |
| 514 | atomic_set(&fp->refcnt, 1); |
| 515 | fp->len = fprog->len; |
| 516 | |
| 517 | err = sk_chk_filter(fp->insns, fp->len); |
Pavel Emelyanov | d3904b7 | 2007-10-17 21:22:17 -0700 | [diff] [blame] | 518 | if (err) { |
| 519 | sk_filter_uncharge(sk, fp); |
| 520 | return err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 521 | } |
| 522 | |
Pavel Emelyanov | d3904b7 | 2007-10-17 21:22:17 -0700 | [diff] [blame] | 523 | rcu_read_lock_bh(); |
Paul E. McKenney | a898def | 2010-02-22 17:04:49 -0800 | [diff] [blame] | 524 | old_fp = rcu_dereference_bh(sk->sk_filter); |
Pavel Emelyanov | d3904b7 | 2007-10-17 21:22:17 -0700 | [diff] [blame] | 525 | rcu_assign_pointer(sk->sk_filter, fp); |
| 526 | rcu_read_unlock_bh(); |
| 527 | |
Olof Johansson | 9b013e0 | 2007-10-18 21:48:39 -0700 | [diff] [blame] | 528 | if (old_fp) |
| 529 | sk_filter_delayed_uncharge(sk, old_fp); |
Pavel Emelyanov | d3904b7 | 2007-10-17 21:22:17 -0700 | [diff] [blame] | 530 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 531 | } |
Michael S. Tsirkin | 5ff3f07 | 2010-02-14 01:01:00 +0000 | [diff] [blame] | 532 | EXPORT_SYMBOL_GPL(sk_attach_filter); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 533 | |
Pavel Emelyanov | 55b3332 | 2007-10-17 21:21:26 -0700 | [diff] [blame] | 534 | int sk_detach_filter(struct sock *sk) |
| 535 | { |
| 536 | int ret = -ENOENT; |
| 537 | struct sk_filter *filter; |
| 538 | |
| 539 | rcu_read_lock_bh(); |
Paul E. McKenney | a898def | 2010-02-22 17:04:49 -0800 | [diff] [blame] | 540 | filter = rcu_dereference_bh(sk->sk_filter); |
Pavel Emelyanov | 55b3332 | 2007-10-17 21:21:26 -0700 | [diff] [blame] | 541 | if (filter) { |
| 542 | rcu_assign_pointer(sk->sk_filter, NULL); |
Pavel Emelyanov | 47e958e | 2007-10-17 21:22:42 -0700 | [diff] [blame] | 543 | sk_filter_delayed_uncharge(sk, filter); |
Pavel Emelyanov | 55b3332 | 2007-10-17 21:21:26 -0700 | [diff] [blame] | 544 | ret = 0; |
| 545 | } |
| 546 | rcu_read_unlock_bh(); |
| 547 | return ret; |
| 548 | } |
Michael S. Tsirkin | 5ff3f07 | 2010-02-14 01:01:00 +0000 | [diff] [blame] | 549 | EXPORT_SYMBOL_GPL(sk_detach_filter); |