| 1 | /* |
| 2 | * IPv6 fragment reassembly for connection tracking |
| 3 | * |
| 4 | * Copyright (C)2004 USAGI/WIDE Project |
| 5 | * |
| 6 | * Author: |
| 7 | * Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp> |
| 8 | * |
| 9 | * Based on: net/ipv6/reassembly.c |
| 10 | * |
| 11 | * This program is free software; you can redistribute it and/or |
| 12 | * modify it under the terms of the GNU General Public License |
| 13 | * as published by the Free Software Foundation; either version |
| 14 | * 2 of the License, or (at your option) any later version. |
| 15 | */ |
| 16 | |
| 17 | #include <linux/errno.h> |
| 18 | #include <linux/types.h> |
| 19 | #include <linux/string.h> |
| 20 | #include <linux/socket.h> |
| 21 | #include <linux/sockios.h> |
| 22 | #include <linux/jiffies.h> |
| 23 | #include <linux/net.h> |
| 24 | #include <linux/list.h> |
| 25 | #include <linux/netdevice.h> |
| 26 | #include <linux/in6.h> |
| 27 | #include <linux/ipv6.h> |
| 28 | #include <linux/icmpv6.h> |
| 29 | #include <linux/random.h> |
| 30 | |
| 31 | #include <net/sock.h> |
| 32 | #include <net/snmp.h> |
| 33 | #include <net/inet_frag.h> |
| 34 | |
| 35 | #include <net/ipv6.h> |
| 36 | #include <net/protocol.h> |
| 37 | #include <net/transp_v6.h> |
| 38 | #include <net/rawv6.h> |
| 39 | #include <net/ndisc.h> |
| 40 | #include <net/addrconf.h> |
| 41 | #include <net/netfilter/ipv6/nf_conntrack_ipv6.h> |
| 42 | #include <linux/sysctl.h> |
| 43 | #include <linux/netfilter.h> |
| 44 | #include <linux/netfilter_ipv6.h> |
| 45 | #include <linux/kernel.h> |
| 46 | #include <linux/module.h> |
| 47 | |
| 48 | #define NF_CT_FRAG6_HIGH_THRESH 262144 /* == 256*1024 */ |
| 49 | #define NF_CT_FRAG6_LOW_THRESH 196608 /* == 192*1024 */ |
| 50 | #define NF_CT_FRAG6_TIMEOUT IPV6_FRAG_TIMEOUT |
| 51 | |
| 52 | struct nf_ct_frag6_skb_cb |
| 53 | { |
| 54 | struct inet6_skb_parm h; |
| 55 | int offset; |
| 56 | struct sk_buff *orig; |
| 57 | }; |
| 58 | |
| 59 | #define NFCT_FRAG6_CB(skb) ((struct nf_ct_frag6_skb_cb*)((skb)->cb)) |
| 60 | |
| 61 | struct nf_ct_frag6_queue |
| 62 | { |
| 63 | struct inet_frag_queue q; |
| 64 | |
| 65 | __be32 id; /* fragment id */ |
| 66 | struct in6_addr saddr; |
| 67 | struct in6_addr daddr; |
| 68 | |
| 69 | unsigned int csum; |
| 70 | __u16 nhoffset; |
| 71 | }; |
| 72 | |
| 73 | static struct inet_frags nf_frags; |
| 74 | static struct netns_frags nf_init_frags; |
| 75 | |
| 76 | #ifdef CONFIG_SYSCTL |
| 77 | struct ctl_table nf_ct_ipv6_sysctl_table[] = { |
| 78 | { |
| 79 | .procname = "nf_conntrack_frag6_timeout", |
| 80 | .data = &nf_init_frags.timeout, |
| 81 | .maxlen = sizeof(unsigned int), |
| 82 | .mode = 0644, |
| 83 | .proc_handler = proc_dointvec_jiffies, |
| 84 | }, |
| 85 | { |
| 86 | .ctl_name = NET_NF_CONNTRACK_FRAG6_LOW_THRESH, |
| 87 | .procname = "nf_conntrack_frag6_low_thresh", |
| 88 | .data = &nf_init_frags.low_thresh, |
| 89 | .maxlen = sizeof(unsigned int), |
| 90 | .mode = 0644, |
| 91 | .proc_handler = proc_dointvec, |
| 92 | }, |
| 93 | { |
| 94 | .ctl_name = NET_NF_CONNTRACK_FRAG6_HIGH_THRESH, |
| 95 | .procname = "nf_conntrack_frag6_high_thresh", |
| 96 | .data = &nf_init_frags.high_thresh, |
| 97 | .maxlen = sizeof(unsigned int), |
| 98 | .mode = 0644, |
| 99 | .proc_handler = proc_dointvec, |
| 100 | }, |
| 101 | { .ctl_name = 0 } |
| 102 | }; |
| 103 | #endif |
| 104 | |
| 105 | static unsigned int nf_hashfn(struct inet_frag_queue *q) |
| 106 | { |
| 107 | const struct nf_ct_frag6_queue *nq; |
| 108 | |
| 109 | nq = container_of(q, struct nf_ct_frag6_queue, q); |
| 110 | return inet6_hash_frag(nq->id, &nq->saddr, &nq->daddr, nf_frags.rnd); |
| 111 | } |
| 112 | |
| 113 | static void nf_skb_free(struct sk_buff *skb) |
| 114 | { |
| 115 | if (NFCT_FRAG6_CB(skb)->orig) |
| 116 | kfree_skb(NFCT_FRAG6_CB(skb)->orig); |
| 117 | } |
| 118 | |
| 119 | /* Memory Tracking Functions. */ |
| 120 | static inline void frag_kfree_skb(struct sk_buff *skb, unsigned int *work) |
| 121 | { |
| 122 | if (work) |
| 123 | *work -= skb->truesize; |
| 124 | atomic_sub(skb->truesize, &nf_init_frags.mem); |
| 125 | nf_skb_free(skb); |
| 126 | kfree_skb(skb); |
| 127 | } |
| 128 | |
| 129 | /* Destruction primitives. */ |
| 130 | |
| 131 | static __inline__ void fq_put(struct nf_ct_frag6_queue *fq) |
| 132 | { |
| 133 | inet_frag_put(&fq->q, &nf_frags); |
| 134 | } |
| 135 | |
| 136 | /* Kill fq entry. It is not destroyed immediately, |
| 137 | * because caller (and someone more) holds reference count. |
| 138 | */ |
| 139 | static __inline__ void fq_kill(struct nf_ct_frag6_queue *fq) |
| 140 | { |
| 141 | inet_frag_kill(&fq->q, &nf_frags); |
| 142 | } |
| 143 | |
| 144 | static void nf_ct_frag6_evictor(void) |
| 145 | { |
| 146 | local_bh_disable(); |
| 147 | inet_frag_evictor(&nf_init_frags, &nf_frags); |
| 148 | local_bh_enable(); |
| 149 | } |
| 150 | |
| 151 | static void nf_ct_frag6_expire(unsigned long data) |
| 152 | { |
| 153 | struct nf_ct_frag6_queue *fq; |
| 154 | |
| 155 | fq = container_of((struct inet_frag_queue *)data, |
| 156 | struct nf_ct_frag6_queue, q); |
| 157 | |
| 158 | spin_lock(&fq->q.lock); |
| 159 | |
| 160 | if (fq->q.last_in & INET_FRAG_COMPLETE) |
| 161 | goto out; |
| 162 | |
| 163 | fq_kill(fq); |
| 164 | |
| 165 | out: |
| 166 | spin_unlock(&fq->q.lock); |
| 167 | fq_put(fq); |
| 168 | } |
| 169 | |
| 170 | /* Creation primitives. */ |
| 171 | |
| 172 | static __inline__ struct nf_ct_frag6_queue * |
| 173 | fq_find(__be32 id, struct in6_addr *src, struct in6_addr *dst) |
| 174 | { |
| 175 | struct inet_frag_queue *q; |
| 176 | struct ip6_create_arg arg; |
| 177 | unsigned int hash; |
| 178 | |
| 179 | arg.id = id; |
| 180 | arg.src = src; |
| 181 | arg.dst = dst; |
| 182 | |
| 183 | read_lock_bh(&nf_frags.lock); |
| 184 | hash = inet6_hash_frag(id, src, dst, nf_frags.rnd); |
| 185 | |
| 186 | q = inet_frag_find(&nf_init_frags, &nf_frags, &arg, hash); |
| 187 | local_bh_enable(); |
| 188 | if (q == NULL) |
| 189 | goto oom; |
| 190 | |
| 191 | return container_of(q, struct nf_ct_frag6_queue, q); |
| 192 | |
| 193 | oom: |
| 194 | pr_debug("Can't alloc new queue\n"); |
| 195 | return NULL; |
| 196 | } |
| 197 | |
| 198 | |
| 199 | static int nf_ct_frag6_queue(struct nf_ct_frag6_queue *fq, struct sk_buff *skb, |
| 200 | const struct frag_hdr *fhdr, int nhoff) |
| 201 | { |
| 202 | struct sk_buff *prev, *next; |
| 203 | int offset, end; |
| 204 | |
| 205 | if (fq->q.last_in & INET_FRAG_COMPLETE) { |
| 206 | pr_debug("Allready completed\n"); |
| 207 | goto err; |
| 208 | } |
| 209 | |
| 210 | offset = ntohs(fhdr->frag_off) & ~0x7; |
| 211 | end = offset + (ntohs(ipv6_hdr(skb)->payload_len) - |
| 212 | ((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1))); |
| 213 | |
| 214 | if ((unsigned int)end > IPV6_MAXPLEN) { |
| 215 | pr_debug("offset is too large.\n"); |
| 216 | return -1; |
| 217 | } |
| 218 | |
| 219 | if (skb->ip_summed == CHECKSUM_COMPLETE) { |
| 220 | const unsigned char *nh = skb_network_header(skb); |
| 221 | skb->csum = csum_sub(skb->csum, |
| 222 | csum_partial(nh, (u8 *)(fhdr + 1) - nh, |
| 223 | 0)); |
| 224 | } |
| 225 | |
| 226 | /* Is this the final fragment? */ |
| 227 | if (!(fhdr->frag_off & htons(IP6_MF))) { |
| 228 | /* If we already have some bits beyond end |
| 229 | * or have different end, the segment is corrupted. |
| 230 | */ |
| 231 | if (end < fq->q.len || |
| 232 | ((fq->q.last_in & INET_FRAG_LAST_IN) && end != fq->q.len)) { |
| 233 | pr_debug("already received last fragment\n"); |
| 234 | goto err; |
| 235 | } |
| 236 | fq->q.last_in |= INET_FRAG_LAST_IN; |
| 237 | fq->q.len = end; |
| 238 | } else { |
| 239 | /* Check if the fragment is rounded to 8 bytes. |
| 240 | * Required by the RFC. |
| 241 | */ |
| 242 | if (end & 0x7) { |
| 243 | /* RFC2460 says always send parameter problem in |
| 244 | * this case. -DaveM |
| 245 | */ |
| 246 | pr_debug("end of fragment not rounded to 8 bytes.\n"); |
| 247 | return -1; |
| 248 | } |
| 249 | if (end > fq->q.len) { |
| 250 | /* Some bits beyond end -> corruption. */ |
| 251 | if (fq->q.last_in & INET_FRAG_LAST_IN) { |
| 252 | pr_debug("last packet already reached.\n"); |
| 253 | goto err; |
| 254 | } |
| 255 | fq->q.len = end; |
| 256 | } |
| 257 | } |
| 258 | |
| 259 | if (end == offset) |
| 260 | goto err; |
| 261 | |
| 262 | /* Point into the IP datagram 'data' part. */ |
| 263 | if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data)) { |
| 264 | pr_debug("queue: message is too short.\n"); |
| 265 | goto err; |
| 266 | } |
| 267 | if (pskb_trim_rcsum(skb, end - offset)) { |
| 268 | pr_debug("Can't trim\n"); |
| 269 | goto err; |
| 270 | } |
| 271 | |
| 272 | /* Find out which fragments are in front and at the back of us |
| 273 | * in the chain of fragments so far. We must know where to put |
| 274 | * this fragment, right? |
| 275 | */ |
| 276 | prev = NULL; |
| 277 | for (next = fq->q.fragments; next != NULL; next = next->next) { |
| 278 | if (NFCT_FRAG6_CB(next)->offset >= offset) |
| 279 | break; /* bingo! */ |
| 280 | prev = next; |
| 281 | } |
| 282 | |
| 283 | /* We found where to put this one. Check for overlap with |
| 284 | * preceding fragment, and, if needed, align things so that |
| 285 | * any overlaps are eliminated. |
| 286 | */ |
| 287 | if (prev) { |
| 288 | int i = (NFCT_FRAG6_CB(prev)->offset + prev->len) - offset; |
| 289 | |
| 290 | if (i > 0) { |
| 291 | offset += i; |
| 292 | if (end <= offset) { |
| 293 | pr_debug("overlap\n"); |
| 294 | goto err; |
| 295 | } |
| 296 | if (!pskb_pull(skb, i)) { |
| 297 | pr_debug("Can't pull\n"); |
| 298 | goto err; |
| 299 | } |
| 300 | if (skb->ip_summed != CHECKSUM_UNNECESSARY) |
| 301 | skb->ip_summed = CHECKSUM_NONE; |
| 302 | } |
| 303 | } |
| 304 | |
| 305 | /* Look for overlap with succeeding segments. |
| 306 | * If we can merge fragments, do it. |
| 307 | */ |
| 308 | while (next && NFCT_FRAG6_CB(next)->offset < end) { |
| 309 | /* overlap is 'i' bytes */ |
| 310 | int i = end - NFCT_FRAG6_CB(next)->offset; |
| 311 | |
| 312 | if (i < next->len) { |
| 313 | /* Eat head of the next overlapped fragment |
| 314 | * and leave the loop. The next ones cannot overlap. |
| 315 | */ |
| 316 | pr_debug("Eat head of the overlapped parts.: %d", i); |
| 317 | if (!pskb_pull(next, i)) |
| 318 | goto err; |
| 319 | |
| 320 | /* next fragment */ |
| 321 | NFCT_FRAG6_CB(next)->offset += i; |
| 322 | fq->q.meat -= i; |
| 323 | if (next->ip_summed != CHECKSUM_UNNECESSARY) |
| 324 | next->ip_summed = CHECKSUM_NONE; |
| 325 | break; |
| 326 | } else { |
| 327 | struct sk_buff *free_it = next; |
| 328 | |
| 329 | /* Old fragmnet is completely overridden with |
| 330 | * new one drop it. |
| 331 | */ |
| 332 | next = next->next; |
| 333 | |
| 334 | if (prev) |
| 335 | prev->next = next; |
| 336 | else |
| 337 | fq->q.fragments = next; |
| 338 | |
| 339 | fq->q.meat -= free_it->len; |
| 340 | frag_kfree_skb(free_it, NULL); |
| 341 | } |
| 342 | } |
| 343 | |
| 344 | NFCT_FRAG6_CB(skb)->offset = offset; |
| 345 | |
| 346 | /* Insert this fragment in the chain of fragments. */ |
| 347 | skb->next = next; |
| 348 | if (prev) |
| 349 | prev->next = skb; |
| 350 | else |
| 351 | fq->q.fragments = skb; |
| 352 | |
| 353 | skb->dev = NULL; |
| 354 | fq->q.stamp = skb->tstamp; |
| 355 | fq->q.meat += skb->len; |
| 356 | atomic_add(skb->truesize, &nf_init_frags.mem); |
| 357 | |
| 358 | /* The first fragment. |
| 359 | * nhoffset is obtained from the first fragment, of course. |
| 360 | */ |
| 361 | if (offset == 0) { |
| 362 | fq->nhoffset = nhoff; |
| 363 | fq->q.last_in |= INET_FRAG_FIRST_IN; |
| 364 | } |
| 365 | write_lock(&nf_frags.lock); |
| 366 | list_move_tail(&fq->q.lru_list, &nf_init_frags.lru_list); |
| 367 | write_unlock(&nf_frags.lock); |
| 368 | return 0; |
| 369 | |
| 370 | err: |
| 371 | return -1; |
| 372 | } |
| 373 | |
| 374 | /* |
| 375 | * Check if this packet is complete. |
| 376 | * Returns NULL on failure by any reason, and pointer |
| 377 | * to current nexthdr field in reassembled frame. |
| 378 | * |
| 379 | * It is called with locked fq, and caller must check that |
| 380 | * queue is eligible for reassembly i.e. it is not COMPLETE, |
| 381 | * the last and the first frames arrived and all the bits are here. |
| 382 | */ |
| 383 | static struct sk_buff * |
| 384 | nf_ct_frag6_reasm(struct nf_ct_frag6_queue *fq, struct net_device *dev) |
| 385 | { |
| 386 | struct sk_buff *fp, *op, *head = fq->q.fragments; |
| 387 | int payload_len; |
| 388 | |
| 389 | fq_kill(fq); |
| 390 | |
| 391 | WARN_ON(head == NULL); |
| 392 | WARN_ON(NFCT_FRAG6_CB(head)->offset != 0); |
| 393 | |
| 394 | /* Unfragmented part is taken from the first segment. */ |
| 395 | payload_len = ((head->data - skb_network_header(head)) - |
| 396 | sizeof(struct ipv6hdr) + fq->q.len - |
| 397 | sizeof(struct frag_hdr)); |
| 398 | if (payload_len > IPV6_MAXPLEN) { |
| 399 | pr_debug("payload len is too large.\n"); |
| 400 | goto out_oversize; |
| 401 | } |
| 402 | |
| 403 | /* Head of list must not be cloned. */ |
| 404 | if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) { |
| 405 | pr_debug("skb is cloned but can't expand head"); |
| 406 | goto out_oom; |
| 407 | } |
| 408 | |
| 409 | /* If the first fragment is fragmented itself, we split |
| 410 | * it to two chunks: the first with data and paged part |
| 411 | * and the second, holding only fragments. */ |
| 412 | if (skb_has_frags(head)) { |
| 413 | struct sk_buff *clone; |
| 414 | int i, plen = 0; |
| 415 | |
| 416 | if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) { |
| 417 | pr_debug("Can't alloc skb\n"); |
| 418 | goto out_oom; |
| 419 | } |
| 420 | clone->next = head->next; |
| 421 | head->next = clone; |
| 422 | skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; |
| 423 | skb_frag_list_init(head); |
| 424 | for (i=0; i<skb_shinfo(head)->nr_frags; i++) |
| 425 | plen += skb_shinfo(head)->frags[i].size; |
| 426 | clone->len = clone->data_len = head->data_len - plen; |
| 427 | head->data_len -= clone->len; |
| 428 | head->len -= clone->len; |
| 429 | clone->csum = 0; |
| 430 | clone->ip_summed = head->ip_summed; |
| 431 | |
| 432 | NFCT_FRAG6_CB(clone)->orig = NULL; |
| 433 | atomic_add(clone->truesize, &nf_init_frags.mem); |
| 434 | } |
| 435 | |
| 436 | /* We have to remove fragment header from datagram and to relocate |
| 437 | * header in order to calculate ICV correctly. */ |
| 438 | skb_network_header(head)[fq->nhoffset] = skb_transport_header(head)[0]; |
| 439 | memmove(head->head + sizeof(struct frag_hdr), head->head, |
| 440 | (head->data - head->head) - sizeof(struct frag_hdr)); |
| 441 | head->mac_header += sizeof(struct frag_hdr); |
| 442 | head->network_header += sizeof(struct frag_hdr); |
| 443 | |
| 444 | skb_shinfo(head)->frag_list = head->next; |
| 445 | skb_reset_transport_header(head); |
| 446 | skb_push(head, head->data - skb_network_header(head)); |
| 447 | atomic_sub(head->truesize, &nf_init_frags.mem); |
| 448 | |
| 449 | for (fp=head->next; fp; fp = fp->next) { |
| 450 | head->data_len += fp->len; |
| 451 | head->len += fp->len; |
| 452 | if (head->ip_summed != fp->ip_summed) |
| 453 | head->ip_summed = CHECKSUM_NONE; |
| 454 | else if (head->ip_summed == CHECKSUM_COMPLETE) |
| 455 | head->csum = csum_add(head->csum, fp->csum); |
| 456 | head->truesize += fp->truesize; |
| 457 | atomic_sub(fp->truesize, &nf_init_frags.mem); |
| 458 | } |
| 459 | |
| 460 | head->next = NULL; |
| 461 | head->dev = dev; |
| 462 | head->tstamp = fq->q.stamp; |
| 463 | ipv6_hdr(head)->payload_len = htons(payload_len); |
| 464 | |
| 465 | /* Yes, and fold redundant checksum back. 8) */ |
| 466 | if (head->ip_summed == CHECKSUM_COMPLETE) |
| 467 | head->csum = csum_partial(skb_network_header(head), |
| 468 | skb_network_header_len(head), |
| 469 | head->csum); |
| 470 | |
| 471 | fq->q.fragments = NULL; |
| 472 | |
| 473 | /* all original skbs are linked into the NFCT_FRAG6_CB(head).orig */ |
| 474 | fp = skb_shinfo(head)->frag_list; |
| 475 | if (NFCT_FRAG6_CB(fp)->orig == NULL) |
| 476 | /* at above code, head skb is divided into two skbs. */ |
| 477 | fp = fp->next; |
| 478 | |
| 479 | op = NFCT_FRAG6_CB(head)->orig; |
| 480 | for (; fp; fp = fp->next) { |
| 481 | struct sk_buff *orig = NFCT_FRAG6_CB(fp)->orig; |
| 482 | |
| 483 | op->next = orig; |
| 484 | op = orig; |
| 485 | NFCT_FRAG6_CB(fp)->orig = NULL; |
| 486 | } |
| 487 | |
| 488 | return head; |
| 489 | |
| 490 | out_oversize: |
| 491 | if (net_ratelimit()) |
| 492 | printk(KERN_DEBUG "nf_ct_frag6_reasm: payload len = %d\n", payload_len); |
| 493 | goto out_fail; |
| 494 | out_oom: |
| 495 | if (net_ratelimit()) |
| 496 | printk(KERN_DEBUG "nf_ct_frag6_reasm: no memory for reassembly\n"); |
| 497 | out_fail: |
| 498 | return NULL; |
| 499 | } |
| 500 | |
| 501 | /* |
| 502 | * find the header just before Fragment Header. |
| 503 | * |
| 504 | * if success return 0 and set ... |
| 505 | * (*prevhdrp): the value of "Next Header Field" in the header |
| 506 | * just before Fragment Header. |
| 507 | * (*prevhoff): the offset of "Next Header Field" in the header |
| 508 | * just before Fragment Header. |
| 509 | * (*fhoff) : the offset of Fragment Header. |
| 510 | * |
| 511 | * Based on ipv6_skip_hdr() in net/ipv6/exthdr.c |
| 512 | * |
| 513 | */ |
| 514 | static int |
| 515 | find_prev_fhdr(struct sk_buff *skb, u8 *prevhdrp, int *prevhoff, int *fhoff) |
| 516 | { |
| 517 | u8 nexthdr = ipv6_hdr(skb)->nexthdr; |
| 518 | const int netoff = skb_network_offset(skb); |
| 519 | u8 prev_nhoff = netoff + offsetof(struct ipv6hdr, nexthdr); |
| 520 | int start = netoff + sizeof(struct ipv6hdr); |
| 521 | int len = skb->len - start; |
| 522 | u8 prevhdr = NEXTHDR_IPV6; |
| 523 | |
| 524 | while (nexthdr != NEXTHDR_FRAGMENT) { |
| 525 | struct ipv6_opt_hdr hdr; |
| 526 | int hdrlen; |
| 527 | |
| 528 | if (!ipv6_ext_hdr(nexthdr)) { |
| 529 | return -1; |
| 530 | } |
| 531 | if (nexthdr == NEXTHDR_NONE) { |
| 532 | pr_debug("next header is none\n"); |
| 533 | return -1; |
| 534 | } |
| 535 | if (len < (int)sizeof(struct ipv6_opt_hdr)) { |
| 536 | pr_debug("too short\n"); |
| 537 | return -1; |
| 538 | } |
| 539 | if (skb_copy_bits(skb, start, &hdr, sizeof(hdr))) |
| 540 | BUG(); |
| 541 | if (nexthdr == NEXTHDR_AUTH) |
| 542 | hdrlen = (hdr.hdrlen+2)<<2; |
| 543 | else |
| 544 | hdrlen = ipv6_optlen(&hdr); |
| 545 | |
| 546 | prevhdr = nexthdr; |
| 547 | prev_nhoff = start; |
| 548 | |
| 549 | nexthdr = hdr.nexthdr; |
| 550 | len -= hdrlen; |
| 551 | start += hdrlen; |
| 552 | } |
| 553 | |
| 554 | if (len < 0) |
| 555 | return -1; |
| 556 | |
| 557 | *prevhdrp = prevhdr; |
| 558 | *prevhoff = prev_nhoff; |
| 559 | *fhoff = start; |
| 560 | |
| 561 | return 0; |
| 562 | } |
| 563 | |
| 564 | struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb) |
| 565 | { |
| 566 | struct sk_buff *clone; |
| 567 | struct net_device *dev = skb->dev; |
| 568 | struct frag_hdr *fhdr; |
| 569 | struct nf_ct_frag6_queue *fq; |
| 570 | struct ipv6hdr *hdr; |
| 571 | int fhoff, nhoff; |
| 572 | u8 prevhdr; |
| 573 | struct sk_buff *ret_skb = NULL; |
| 574 | |
| 575 | /* Jumbo payload inhibits frag. header */ |
| 576 | if (ipv6_hdr(skb)->payload_len == 0) { |
| 577 | pr_debug("payload len = 0\n"); |
| 578 | return skb; |
| 579 | } |
| 580 | |
| 581 | if (find_prev_fhdr(skb, &prevhdr, &nhoff, &fhoff) < 0) |
| 582 | return skb; |
| 583 | |
| 584 | clone = skb_clone(skb, GFP_ATOMIC); |
| 585 | if (clone == NULL) { |
| 586 | pr_debug("Can't clone skb\n"); |
| 587 | return skb; |
| 588 | } |
| 589 | |
| 590 | NFCT_FRAG6_CB(clone)->orig = skb; |
| 591 | |
| 592 | if (!pskb_may_pull(clone, fhoff + sizeof(*fhdr))) { |
| 593 | pr_debug("message is too short.\n"); |
| 594 | goto ret_orig; |
| 595 | } |
| 596 | |
| 597 | skb_set_transport_header(clone, fhoff); |
| 598 | hdr = ipv6_hdr(clone); |
| 599 | fhdr = (struct frag_hdr *)skb_transport_header(clone); |
| 600 | |
| 601 | if (!(fhdr->frag_off & htons(0xFFF9))) { |
| 602 | pr_debug("Invalid fragment offset\n"); |
| 603 | /* It is not a fragmented frame */ |
| 604 | goto ret_orig; |
| 605 | } |
| 606 | |
| 607 | if (atomic_read(&nf_init_frags.mem) > nf_init_frags.high_thresh) |
| 608 | nf_ct_frag6_evictor(); |
| 609 | |
| 610 | fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr); |
| 611 | if (fq == NULL) { |
| 612 | pr_debug("Can't find and can't create new queue\n"); |
| 613 | goto ret_orig; |
| 614 | } |
| 615 | |
| 616 | spin_lock_bh(&fq->q.lock); |
| 617 | |
| 618 | if (nf_ct_frag6_queue(fq, clone, fhdr, nhoff) < 0) { |
| 619 | spin_unlock_bh(&fq->q.lock); |
| 620 | pr_debug("Can't insert skb to queue\n"); |
| 621 | fq_put(fq); |
| 622 | goto ret_orig; |
| 623 | } |
| 624 | |
| 625 | if (fq->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && |
| 626 | fq->q.meat == fq->q.len) { |
| 627 | ret_skb = nf_ct_frag6_reasm(fq, dev); |
| 628 | if (ret_skb == NULL) |
| 629 | pr_debug("Can't reassemble fragmented packets\n"); |
| 630 | } |
| 631 | spin_unlock_bh(&fq->q.lock); |
| 632 | |
| 633 | fq_put(fq); |
| 634 | return ret_skb; |
| 635 | |
| 636 | ret_orig: |
| 637 | kfree_skb(clone); |
| 638 | return skb; |
| 639 | } |
| 640 | |
| 641 | void nf_ct_frag6_output(unsigned int hooknum, struct sk_buff *skb, |
| 642 | struct net_device *in, struct net_device *out, |
| 643 | int (*okfn)(struct sk_buff *)) |
| 644 | { |
| 645 | struct sk_buff *s, *s2; |
| 646 | |
| 647 | for (s = NFCT_FRAG6_CB(skb)->orig; s;) { |
| 648 | nf_conntrack_put_reasm(s->nfct_reasm); |
| 649 | nf_conntrack_get_reasm(skb); |
| 650 | s->nfct_reasm = skb; |
| 651 | |
| 652 | s2 = s->next; |
| 653 | s->next = NULL; |
| 654 | |
| 655 | NF_HOOK_THRESH(PF_INET6, hooknum, s, in, out, okfn, |
| 656 | NF_IP6_PRI_CONNTRACK_DEFRAG + 1); |
| 657 | s = s2; |
| 658 | } |
| 659 | nf_conntrack_put_reasm(skb); |
| 660 | } |
| 661 | |
| 662 | int nf_ct_frag6_init(void) |
| 663 | { |
| 664 | nf_frags.hashfn = nf_hashfn; |
| 665 | nf_frags.constructor = ip6_frag_init; |
| 666 | nf_frags.destructor = NULL; |
| 667 | nf_frags.skb_free = nf_skb_free; |
| 668 | nf_frags.qsize = sizeof(struct nf_ct_frag6_queue); |
| 669 | nf_frags.match = ip6_frag_match; |
| 670 | nf_frags.frag_expire = nf_ct_frag6_expire; |
| 671 | nf_frags.secret_interval = 10 * 60 * HZ; |
| 672 | nf_init_frags.timeout = IPV6_FRAG_TIMEOUT; |
| 673 | nf_init_frags.high_thresh = 256 * 1024; |
| 674 | nf_init_frags.low_thresh = 192 * 1024; |
| 675 | inet_frags_init_net(&nf_init_frags); |
| 676 | inet_frags_init(&nf_frags); |
| 677 | |
| 678 | return 0; |
| 679 | } |
| 680 | |
| 681 | void nf_ct_frag6_cleanup(void) |
| 682 | { |
| 683 | inet_frags_fini(&nf_frags); |
| 684 | |
| 685 | nf_init_frags.low_thresh = 0; |
| 686 | nf_ct_frag6_evictor(); |
| 687 | } |