| 1 | /* |
| 2 | * INET An implementation of the TCP/IP protocol suite for the LINUX |
| 3 | * operating system. INET is implemented using the BSD Socket |
| 4 | * interface as the means of communication with the user level. |
| 5 | * |
| 6 | * The IP fragmentation functionality. |
| 7 | * |
| 8 | * Authors: Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG> |
| 9 | * Alan Cox <alan@lxorguk.ukuu.org.uk> |
| 10 | * |
| 11 | * Fixes: |
| 12 | * Alan Cox : Split from ip.c , see ip_input.c for history. |
| 13 | * David S. Miller : Begin massive cleanup... |
| 14 | * Andi Kleen : Add sysctls. |
| 15 | * xxxx : Overlapfrag bug. |
| 16 | * Ultima : ip_expire() kernel panic. |
| 17 | * Bill Hawes : Frag accounting and evictor fixes. |
| 18 | * John McDonald : 0 length frag bug. |
| 19 | * Alexey Kuznetsov: SMP races, threading, cleanup. |
| 20 | * Patrick McHardy : LRU queue of frag heads for evictor. |
| 21 | */ |
| 22 | |
| 23 | #include <linux/compiler.h> |
| 24 | #include <linux/module.h> |
| 25 | #include <linux/types.h> |
| 26 | #include <linux/mm.h> |
| 27 | #include <linux/jiffies.h> |
| 28 | #include <linux/skbuff.h> |
| 29 | #include <linux/list.h> |
| 30 | #include <linux/ip.h> |
| 31 | #include <linux/icmp.h> |
| 32 | #include <linux/netdevice.h> |
| 33 | #include <linux/jhash.h> |
| 34 | #include <linux/random.h> |
| 35 | #include <linux/slab.h> |
| 36 | #include <net/route.h> |
| 37 | #include <net/dst.h> |
| 38 | #include <net/sock.h> |
| 39 | #include <net/ip.h> |
| 40 | #include <net/icmp.h> |
| 41 | #include <net/checksum.h> |
| 42 | #include <net/inetpeer.h> |
| 43 | #include <net/inet_frag.h> |
| 44 | #include <linux/tcp.h> |
| 45 | #include <linux/udp.h> |
| 46 | #include <linux/inet.h> |
| 47 | #include <linux/netfilter_ipv4.h> |
| 48 | |
| 49 | /* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6 |
| 50 | * code now. If you change something here, _PLEASE_ update ipv6/reassembly.c |
| 51 | * as well. Or notify me, at least. --ANK |
| 52 | */ |
| 53 | |
| 54 | static int sysctl_ipfrag_max_dist __read_mostly = 64; |
| 55 | |
| 56 | struct ipfrag_skb_cb |
| 57 | { |
| 58 | struct inet_skb_parm h; |
| 59 | int offset; |
| 60 | }; |
| 61 | |
| 62 | #define FRAG_CB(skb) ((struct ipfrag_skb_cb *)((skb)->cb)) |
| 63 | |
| 64 | /* Describe an entry in the "incomplete datagrams" queue. */ |
| 65 | struct ipq { |
| 66 | struct inet_frag_queue q; |
| 67 | |
| 68 | u32 user; |
| 69 | __be32 saddr; |
| 70 | __be32 daddr; |
| 71 | __be16 id; |
| 72 | u8 protocol; |
| 73 | int iif; |
| 74 | unsigned int rid; |
| 75 | struct inet_peer *peer; |
| 76 | }; |
| 77 | |
| 78 | static struct inet_frags ip4_frags; |
| 79 | |
| 80 | int ip_frag_nqueues(struct net *net) |
| 81 | { |
| 82 | return net->ipv4.frags.nqueues; |
| 83 | } |
| 84 | |
| 85 | int ip_frag_mem(struct net *net) |
| 86 | { |
| 87 | return atomic_read(&net->ipv4.frags.mem); |
| 88 | } |
| 89 | |
| 90 | static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, |
| 91 | struct net_device *dev); |
| 92 | |
| 93 | struct ip4_create_arg { |
| 94 | struct iphdr *iph; |
| 95 | u32 user; |
| 96 | }; |
| 97 | |
| 98 | static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot) |
| 99 | { |
| 100 | return jhash_3words((__force u32)id << 16 | prot, |
| 101 | (__force u32)saddr, (__force u32)daddr, |
| 102 | ip4_frags.rnd) & (INETFRAGS_HASHSZ - 1); |
| 103 | } |
| 104 | |
| 105 | static unsigned int ip4_hashfn(struct inet_frag_queue *q) |
| 106 | { |
| 107 | struct ipq *ipq; |
| 108 | |
| 109 | ipq = container_of(q, struct ipq, q); |
| 110 | return ipqhashfn(ipq->id, ipq->saddr, ipq->daddr, ipq->protocol); |
| 111 | } |
| 112 | |
| 113 | static int ip4_frag_match(struct inet_frag_queue *q, void *a) |
| 114 | { |
| 115 | struct ipq *qp; |
| 116 | struct ip4_create_arg *arg = a; |
| 117 | |
| 118 | qp = container_of(q, struct ipq, q); |
| 119 | return (qp->id == arg->iph->id && |
| 120 | qp->saddr == arg->iph->saddr && |
| 121 | qp->daddr == arg->iph->daddr && |
| 122 | qp->protocol == arg->iph->protocol && |
| 123 | qp->user == arg->user); |
| 124 | } |
| 125 | |
| 126 | /* Memory Tracking Functions. */ |
| 127 | static void frag_kfree_skb(struct netns_frags *nf, struct sk_buff *skb) |
| 128 | { |
| 129 | atomic_sub(skb->truesize, &nf->mem); |
| 130 | kfree_skb(skb); |
| 131 | } |
| 132 | |
| 133 | static void ip4_frag_init(struct inet_frag_queue *q, void *a) |
| 134 | { |
| 135 | struct ipq *qp = container_of(q, struct ipq, q); |
| 136 | struct ip4_create_arg *arg = a; |
| 137 | |
| 138 | qp->protocol = arg->iph->protocol; |
| 139 | qp->id = arg->iph->id; |
| 140 | qp->saddr = arg->iph->saddr; |
| 141 | qp->daddr = arg->iph->daddr; |
| 142 | qp->user = arg->user; |
| 143 | qp->peer = sysctl_ipfrag_max_dist ? |
| 144 | inet_getpeer(arg->iph->saddr, 1) : NULL; |
| 145 | } |
| 146 | |
| 147 | static __inline__ void ip4_frag_free(struct inet_frag_queue *q) |
| 148 | { |
| 149 | struct ipq *qp; |
| 150 | |
| 151 | qp = container_of(q, struct ipq, q); |
| 152 | if (qp->peer) |
| 153 | inet_putpeer(qp->peer); |
| 154 | } |
| 155 | |
| 156 | |
| 157 | /* Destruction primitives. */ |
| 158 | |
| 159 | static __inline__ void ipq_put(struct ipq *ipq) |
| 160 | { |
| 161 | inet_frag_put(&ipq->q, &ip4_frags); |
| 162 | } |
| 163 | |
| 164 | /* Kill ipq entry. It is not destroyed immediately, |
| 165 | * because caller (and someone more) holds reference count. |
| 166 | */ |
| 167 | static void ipq_kill(struct ipq *ipq) |
| 168 | { |
| 169 | inet_frag_kill(&ipq->q, &ip4_frags); |
| 170 | } |
| 171 | |
| 172 | /* Memory limiting on fragments. Evictor trashes the oldest |
| 173 | * fragment queue until we are back under the threshold. |
| 174 | */ |
| 175 | static void ip_evictor(struct net *net) |
| 176 | { |
| 177 | int evicted; |
| 178 | |
| 179 | evicted = inet_frag_evictor(&net->ipv4.frags, &ip4_frags); |
| 180 | if (evicted) |
| 181 | IP_ADD_STATS_BH(net, IPSTATS_MIB_REASMFAILS, evicted); |
| 182 | } |
| 183 | |
| 184 | /* |
| 185 | * Oops, a fragment queue timed out. Kill it and send an ICMP reply. |
| 186 | */ |
| 187 | static void ip_expire(unsigned long arg) |
| 188 | { |
| 189 | struct ipq *qp; |
| 190 | struct net *net; |
| 191 | |
| 192 | qp = container_of((struct inet_frag_queue *) arg, struct ipq, q); |
| 193 | net = container_of(qp->q.net, struct net, ipv4.frags); |
| 194 | |
| 195 | spin_lock(&qp->q.lock); |
| 196 | |
| 197 | if (qp->q.last_in & INET_FRAG_COMPLETE) |
| 198 | goto out; |
| 199 | |
| 200 | ipq_kill(qp); |
| 201 | |
| 202 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMTIMEOUT); |
| 203 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); |
| 204 | |
| 205 | if ((qp->q.last_in & INET_FRAG_FIRST_IN) && qp->q.fragments != NULL) { |
| 206 | struct sk_buff *head = qp->q.fragments; |
| 207 | |
| 208 | rcu_read_lock(); |
| 209 | head->dev = dev_get_by_index_rcu(net, qp->iif); |
| 210 | if (!head->dev) |
| 211 | goto out_rcu_unlock; |
| 212 | |
| 213 | /* |
| 214 | * Only search router table for the head fragment, |
| 215 | * when defraging timeout at PRE_ROUTING HOOK. |
| 216 | */ |
| 217 | if (qp->user == IP_DEFRAG_CONNTRACK_IN && !skb_dst(head)) { |
| 218 | const struct iphdr *iph = ip_hdr(head); |
| 219 | int err = ip_route_input(head, iph->daddr, iph->saddr, |
| 220 | iph->tos, head->dev); |
| 221 | if (unlikely(err)) |
| 222 | goto out_rcu_unlock; |
| 223 | |
| 224 | /* |
| 225 | * Only an end host needs to send an ICMP |
| 226 | * "Fragment Reassembly Timeout" message, per RFC792. |
| 227 | */ |
| 228 | if (skb_rtable(head)->rt_type != RTN_LOCAL) |
| 229 | goto out_rcu_unlock; |
| 230 | |
| 231 | } |
| 232 | |
| 233 | /* Send an ICMP "Fragment Reassembly Timeout" message. */ |
| 234 | icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0); |
| 235 | out_rcu_unlock: |
| 236 | rcu_read_unlock(); |
| 237 | } |
| 238 | out: |
| 239 | spin_unlock(&qp->q.lock); |
| 240 | ipq_put(qp); |
| 241 | } |
| 242 | |
| 243 | /* Find the correct entry in the "incomplete datagrams" queue for |
| 244 | * this IP datagram, and create new one, if nothing is found. |
| 245 | */ |
| 246 | static inline struct ipq *ip_find(struct net *net, struct iphdr *iph, u32 user) |
| 247 | { |
| 248 | struct inet_frag_queue *q; |
| 249 | struct ip4_create_arg arg; |
| 250 | unsigned int hash; |
| 251 | |
| 252 | arg.iph = iph; |
| 253 | arg.user = user; |
| 254 | |
| 255 | read_lock(&ip4_frags.lock); |
| 256 | hash = ipqhashfn(iph->id, iph->saddr, iph->daddr, iph->protocol); |
| 257 | |
| 258 | q = inet_frag_find(&net->ipv4.frags, &ip4_frags, &arg, hash); |
| 259 | if (q == NULL) |
| 260 | goto out_nomem; |
| 261 | |
| 262 | return container_of(q, struct ipq, q); |
| 263 | |
| 264 | out_nomem: |
| 265 | LIMIT_NETDEBUG(KERN_ERR "ip_frag_create: no memory left !\n"); |
| 266 | return NULL; |
| 267 | } |
| 268 | |
| 269 | /* Is the fragment too far ahead to be part of ipq? */ |
| 270 | static inline int ip_frag_too_far(struct ipq *qp) |
| 271 | { |
| 272 | struct inet_peer *peer = qp->peer; |
| 273 | unsigned int max = sysctl_ipfrag_max_dist; |
| 274 | unsigned int start, end; |
| 275 | |
| 276 | int rc; |
| 277 | |
| 278 | if (!peer || !max) |
| 279 | return 0; |
| 280 | |
| 281 | start = qp->rid; |
| 282 | end = atomic_inc_return(&peer->rid); |
| 283 | qp->rid = end; |
| 284 | |
| 285 | rc = qp->q.fragments && (end - start) > max; |
| 286 | |
| 287 | if (rc) { |
| 288 | struct net *net; |
| 289 | |
| 290 | net = container_of(qp->q.net, struct net, ipv4.frags); |
| 291 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); |
| 292 | } |
| 293 | |
| 294 | return rc; |
| 295 | } |
| 296 | |
| 297 | static int ip_frag_reinit(struct ipq *qp) |
| 298 | { |
| 299 | struct sk_buff *fp; |
| 300 | |
| 301 | if (!mod_timer(&qp->q.timer, jiffies + qp->q.net->timeout)) { |
| 302 | atomic_inc(&qp->q.refcnt); |
| 303 | return -ETIMEDOUT; |
| 304 | } |
| 305 | |
| 306 | fp = qp->q.fragments; |
| 307 | do { |
| 308 | struct sk_buff *xp = fp->next; |
| 309 | frag_kfree_skb(qp->q.net, fp); |
| 310 | fp = xp; |
| 311 | } while (fp); |
| 312 | |
| 313 | qp->q.last_in = 0; |
| 314 | qp->q.len = 0; |
| 315 | qp->q.meat = 0; |
| 316 | qp->q.fragments = NULL; |
| 317 | qp->q.fragments_tail = NULL; |
| 318 | qp->iif = 0; |
| 319 | |
| 320 | return 0; |
| 321 | } |
| 322 | |
| 323 | /* Add new segment to existing queue. */ |
| 324 | static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) |
| 325 | { |
| 326 | struct sk_buff *prev, *next; |
| 327 | struct net_device *dev; |
| 328 | int flags, offset; |
| 329 | int ihl, end; |
| 330 | int err = -ENOENT; |
| 331 | |
| 332 | if (qp->q.last_in & INET_FRAG_COMPLETE) |
| 333 | goto err; |
| 334 | |
| 335 | if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && |
| 336 | unlikely(ip_frag_too_far(qp)) && |
| 337 | unlikely(err = ip_frag_reinit(qp))) { |
| 338 | ipq_kill(qp); |
| 339 | goto err; |
| 340 | } |
| 341 | |
| 342 | offset = ntohs(ip_hdr(skb)->frag_off); |
| 343 | flags = offset & ~IP_OFFSET; |
| 344 | offset &= IP_OFFSET; |
| 345 | offset <<= 3; /* offset is in 8-byte chunks */ |
| 346 | ihl = ip_hdrlen(skb); |
| 347 | |
| 348 | /* Determine the position of this fragment. */ |
| 349 | end = offset + skb->len - ihl; |
| 350 | err = -EINVAL; |
| 351 | |
| 352 | /* Is this the final fragment? */ |
| 353 | if ((flags & IP_MF) == 0) { |
| 354 | /* If we already have some bits beyond end |
| 355 | * or have different end, the segment is corrrupted. |
| 356 | */ |
| 357 | if (end < qp->q.len || |
| 358 | ((qp->q.last_in & INET_FRAG_LAST_IN) && end != qp->q.len)) |
| 359 | goto err; |
| 360 | qp->q.last_in |= INET_FRAG_LAST_IN; |
| 361 | qp->q.len = end; |
| 362 | } else { |
| 363 | if (end&7) { |
| 364 | end &= ~7; |
| 365 | if (skb->ip_summed != CHECKSUM_UNNECESSARY) |
| 366 | skb->ip_summed = CHECKSUM_NONE; |
| 367 | } |
| 368 | if (end > qp->q.len) { |
| 369 | /* Some bits beyond end -> corruption. */ |
| 370 | if (qp->q.last_in & INET_FRAG_LAST_IN) |
| 371 | goto err; |
| 372 | qp->q.len = end; |
| 373 | } |
| 374 | } |
| 375 | if (end == offset) |
| 376 | goto err; |
| 377 | |
| 378 | err = -ENOMEM; |
| 379 | if (pskb_pull(skb, ihl) == NULL) |
| 380 | goto err; |
| 381 | |
| 382 | err = pskb_trim_rcsum(skb, end - offset); |
| 383 | if (err) |
| 384 | goto err; |
| 385 | |
| 386 | /* Find out which fragments are in front and at the back of us |
| 387 | * in the chain of fragments so far. We must know where to put |
| 388 | * this fragment, right? |
| 389 | */ |
| 390 | prev = qp->q.fragments_tail; |
| 391 | if (!prev || FRAG_CB(prev)->offset < offset) { |
| 392 | next = NULL; |
| 393 | goto found; |
| 394 | } |
| 395 | prev = NULL; |
| 396 | for (next = qp->q.fragments; next != NULL; next = next->next) { |
| 397 | if (FRAG_CB(next)->offset >= offset) |
| 398 | break; /* bingo! */ |
| 399 | prev = next; |
| 400 | } |
| 401 | |
| 402 | found: |
| 403 | /* We found where to put this one. Check for overlap with |
| 404 | * preceding fragment, and, if needed, align things so that |
| 405 | * any overlaps are eliminated. |
| 406 | */ |
| 407 | if (prev) { |
| 408 | int i = (FRAG_CB(prev)->offset + prev->len) - offset; |
| 409 | |
| 410 | if (i > 0) { |
| 411 | offset += i; |
| 412 | err = -EINVAL; |
| 413 | if (end <= offset) |
| 414 | goto err; |
| 415 | err = -ENOMEM; |
| 416 | if (!pskb_pull(skb, i)) |
| 417 | goto err; |
| 418 | if (skb->ip_summed != CHECKSUM_UNNECESSARY) |
| 419 | skb->ip_summed = CHECKSUM_NONE; |
| 420 | } |
| 421 | } |
| 422 | |
| 423 | err = -ENOMEM; |
| 424 | |
| 425 | while (next && FRAG_CB(next)->offset < end) { |
| 426 | int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ |
| 427 | |
| 428 | if (i < next->len) { |
| 429 | /* Eat head of the next overlapped fragment |
| 430 | * and leave the loop. The next ones cannot overlap. |
| 431 | */ |
| 432 | if (!pskb_pull(next, i)) |
| 433 | goto err; |
| 434 | FRAG_CB(next)->offset += i; |
| 435 | qp->q.meat -= i; |
| 436 | if (next->ip_summed != CHECKSUM_UNNECESSARY) |
| 437 | next->ip_summed = CHECKSUM_NONE; |
| 438 | break; |
| 439 | } else { |
| 440 | struct sk_buff *free_it = next; |
| 441 | |
| 442 | /* Old fragment is completely overridden with |
| 443 | * new one drop it. |
| 444 | */ |
| 445 | next = next->next; |
| 446 | |
| 447 | if (prev) |
| 448 | prev->next = next; |
| 449 | else |
| 450 | qp->q.fragments = next; |
| 451 | |
| 452 | qp->q.meat -= free_it->len; |
| 453 | frag_kfree_skb(qp->q.net, free_it); |
| 454 | } |
| 455 | } |
| 456 | |
| 457 | FRAG_CB(skb)->offset = offset; |
| 458 | |
| 459 | /* Insert this fragment in the chain of fragments. */ |
| 460 | skb->next = next; |
| 461 | if (!next) |
| 462 | qp->q.fragments_tail = skb; |
| 463 | if (prev) |
| 464 | prev->next = skb; |
| 465 | else |
| 466 | qp->q.fragments = skb; |
| 467 | |
| 468 | dev = skb->dev; |
| 469 | if (dev) { |
| 470 | qp->iif = dev->ifindex; |
| 471 | skb->dev = NULL; |
| 472 | } |
| 473 | qp->q.stamp = skb->tstamp; |
| 474 | qp->q.meat += skb->len; |
| 475 | atomic_add(skb->truesize, &qp->q.net->mem); |
| 476 | if (offset == 0) |
| 477 | qp->q.last_in |= INET_FRAG_FIRST_IN; |
| 478 | |
| 479 | if (qp->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && |
| 480 | qp->q.meat == qp->q.len) |
| 481 | return ip_frag_reasm(qp, prev, dev); |
| 482 | |
| 483 | write_lock(&ip4_frags.lock); |
| 484 | list_move_tail(&qp->q.lru_list, &qp->q.net->lru_list); |
| 485 | write_unlock(&ip4_frags.lock); |
| 486 | return -EINPROGRESS; |
| 487 | |
| 488 | err: |
| 489 | kfree_skb(skb); |
| 490 | return err; |
| 491 | } |
| 492 | |
| 493 | |
| 494 | /* Build a new IP datagram from all its fragments. */ |
| 495 | |
| 496 | static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, |
| 497 | struct net_device *dev) |
| 498 | { |
| 499 | struct net *net = container_of(qp->q.net, struct net, ipv4.frags); |
| 500 | struct iphdr *iph; |
| 501 | struct sk_buff *fp, *head = qp->q.fragments; |
| 502 | int len; |
| 503 | int ihlen; |
| 504 | int err; |
| 505 | |
| 506 | ipq_kill(qp); |
| 507 | |
| 508 | /* Make the one we just received the head. */ |
| 509 | if (prev) { |
| 510 | head = prev->next; |
| 511 | fp = skb_clone(head, GFP_ATOMIC); |
| 512 | if (!fp) |
| 513 | goto out_nomem; |
| 514 | |
| 515 | fp->next = head->next; |
| 516 | if (!fp->next) |
| 517 | qp->q.fragments_tail = fp; |
| 518 | prev->next = fp; |
| 519 | |
| 520 | skb_morph(head, qp->q.fragments); |
| 521 | head->next = qp->q.fragments->next; |
| 522 | |
| 523 | kfree_skb(qp->q.fragments); |
| 524 | qp->q.fragments = head; |
| 525 | } |
| 526 | |
| 527 | WARN_ON(head == NULL); |
| 528 | WARN_ON(FRAG_CB(head)->offset != 0); |
| 529 | |
| 530 | /* Allocate a new buffer for the datagram. */ |
| 531 | ihlen = ip_hdrlen(head); |
| 532 | len = ihlen + qp->q.len; |
| 533 | |
| 534 | err = -E2BIG; |
| 535 | if (len > 65535) |
| 536 | goto out_oversize; |
| 537 | |
| 538 | /* Head of list must not be cloned. */ |
| 539 | if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) |
| 540 | goto out_nomem; |
| 541 | |
| 542 | /* If the first fragment is fragmented itself, we split |
| 543 | * it to two chunks: the first with data and paged part |
| 544 | * and the second, holding only fragments. */ |
| 545 | if (skb_has_frags(head)) { |
| 546 | struct sk_buff *clone; |
| 547 | int i, plen = 0; |
| 548 | |
| 549 | if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) |
| 550 | goto out_nomem; |
| 551 | clone->next = head->next; |
| 552 | head->next = clone; |
| 553 | skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; |
| 554 | skb_frag_list_init(head); |
| 555 | for (i=0; i<skb_shinfo(head)->nr_frags; i++) |
| 556 | plen += skb_shinfo(head)->frags[i].size; |
| 557 | clone->len = clone->data_len = head->data_len - plen; |
| 558 | head->data_len -= clone->len; |
| 559 | head->len -= clone->len; |
| 560 | clone->csum = 0; |
| 561 | clone->ip_summed = head->ip_summed; |
| 562 | atomic_add(clone->truesize, &qp->q.net->mem); |
| 563 | } |
| 564 | |
| 565 | skb_shinfo(head)->frag_list = head->next; |
| 566 | skb_push(head, head->data - skb_network_header(head)); |
| 567 | |
| 568 | for (fp=head->next; fp; fp = fp->next) { |
| 569 | head->data_len += fp->len; |
| 570 | head->len += fp->len; |
| 571 | if (head->ip_summed != fp->ip_summed) |
| 572 | head->ip_summed = CHECKSUM_NONE; |
| 573 | else if (head->ip_summed == CHECKSUM_COMPLETE) |
| 574 | head->csum = csum_add(head->csum, fp->csum); |
| 575 | head->truesize += fp->truesize; |
| 576 | } |
| 577 | atomic_sub(head->truesize, &qp->q.net->mem); |
| 578 | |
| 579 | head->next = NULL; |
| 580 | head->dev = dev; |
| 581 | head->tstamp = qp->q.stamp; |
| 582 | |
| 583 | iph = ip_hdr(head); |
| 584 | iph->frag_off = 0; |
| 585 | iph->tot_len = htons(len); |
| 586 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS); |
| 587 | qp->q.fragments = NULL; |
| 588 | qp->q.fragments_tail = NULL; |
| 589 | return 0; |
| 590 | |
| 591 | out_nomem: |
| 592 | LIMIT_NETDEBUG(KERN_ERR "IP: queue_glue: no memory for gluing " |
| 593 | "queue %p\n", qp); |
| 594 | err = -ENOMEM; |
| 595 | goto out_fail; |
| 596 | out_oversize: |
| 597 | if (net_ratelimit()) |
| 598 | printk(KERN_INFO "Oversized IP packet from %pI4.\n", |
| 599 | &qp->saddr); |
| 600 | out_fail: |
| 601 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); |
| 602 | return err; |
| 603 | } |
| 604 | |
| 605 | /* Process an incoming IP datagram fragment. */ |
| 606 | int ip_defrag(struct sk_buff *skb, u32 user) |
| 607 | { |
| 608 | struct ipq *qp; |
| 609 | struct net *net; |
| 610 | |
| 611 | net = skb->dev ? dev_net(skb->dev) : dev_net(skb_dst(skb)->dev); |
| 612 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMREQDS); |
| 613 | |
| 614 | /* Start by cleaning up the memory. */ |
| 615 | if (atomic_read(&net->ipv4.frags.mem) > net->ipv4.frags.high_thresh) |
| 616 | ip_evictor(net); |
| 617 | |
| 618 | /* Lookup (or create) queue header */ |
| 619 | if ((qp = ip_find(net, ip_hdr(skb), user)) != NULL) { |
| 620 | int ret; |
| 621 | |
| 622 | spin_lock(&qp->q.lock); |
| 623 | |
| 624 | ret = ip_frag_queue(qp, skb); |
| 625 | |
| 626 | spin_unlock(&qp->q.lock); |
| 627 | ipq_put(qp); |
| 628 | return ret; |
| 629 | } |
| 630 | |
| 631 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); |
| 632 | kfree_skb(skb); |
| 633 | return -ENOMEM; |
| 634 | } |
| 635 | |
| 636 | #ifdef CONFIG_SYSCTL |
| 637 | static int zero; |
| 638 | |
| 639 | static struct ctl_table ip4_frags_ns_ctl_table[] = { |
| 640 | { |
| 641 | .procname = "ipfrag_high_thresh", |
| 642 | .data = &init_net.ipv4.frags.high_thresh, |
| 643 | .maxlen = sizeof(int), |
| 644 | .mode = 0644, |
| 645 | .proc_handler = proc_dointvec |
| 646 | }, |
| 647 | { |
| 648 | .procname = "ipfrag_low_thresh", |
| 649 | .data = &init_net.ipv4.frags.low_thresh, |
| 650 | .maxlen = sizeof(int), |
| 651 | .mode = 0644, |
| 652 | .proc_handler = proc_dointvec |
| 653 | }, |
| 654 | { |
| 655 | .procname = "ipfrag_time", |
| 656 | .data = &init_net.ipv4.frags.timeout, |
| 657 | .maxlen = sizeof(int), |
| 658 | .mode = 0644, |
| 659 | .proc_handler = proc_dointvec_jiffies, |
| 660 | }, |
| 661 | { } |
| 662 | }; |
| 663 | |
| 664 | static struct ctl_table ip4_frags_ctl_table[] = { |
| 665 | { |
| 666 | .procname = "ipfrag_secret_interval", |
| 667 | .data = &ip4_frags.secret_interval, |
| 668 | .maxlen = sizeof(int), |
| 669 | .mode = 0644, |
| 670 | .proc_handler = proc_dointvec_jiffies, |
| 671 | }, |
| 672 | { |
| 673 | .procname = "ipfrag_max_dist", |
| 674 | .data = &sysctl_ipfrag_max_dist, |
| 675 | .maxlen = sizeof(int), |
| 676 | .mode = 0644, |
| 677 | .proc_handler = proc_dointvec_minmax, |
| 678 | .extra1 = &zero |
| 679 | }, |
| 680 | { } |
| 681 | }; |
| 682 | |
| 683 | static int __net_init ip4_frags_ns_ctl_register(struct net *net) |
| 684 | { |
| 685 | struct ctl_table *table; |
| 686 | struct ctl_table_header *hdr; |
| 687 | |
| 688 | table = ip4_frags_ns_ctl_table; |
| 689 | if (!net_eq(net, &init_net)) { |
| 690 | table = kmemdup(table, sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL); |
| 691 | if (table == NULL) |
| 692 | goto err_alloc; |
| 693 | |
| 694 | table[0].data = &net->ipv4.frags.high_thresh; |
| 695 | table[1].data = &net->ipv4.frags.low_thresh; |
| 696 | table[2].data = &net->ipv4.frags.timeout; |
| 697 | } |
| 698 | |
| 699 | hdr = register_net_sysctl_table(net, net_ipv4_ctl_path, table); |
| 700 | if (hdr == NULL) |
| 701 | goto err_reg; |
| 702 | |
| 703 | net->ipv4.frags_hdr = hdr; |
| 704 | return 0; |
| 705 | |
| 706 | err_reg: |
| 707 | if (!net_eq(net, &init_net)) |
| 708 | kfree(table); |
| 709 | err_alloc: |
| 710 | return -ENOMEM; |
| 711 | } |
| 712 | |
| 713 | static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net) |
| 714 | { |
| 715 | struct ctl_table *table; |
| 716 | |
| 717 | table = net->ipv4.frags_hdr->ctl_table_arg; |
| 718 | unregister_net_sysctl_table(net->ipv4.frags_hdr); |
| 719 | kfree(table); |
| 720 | } |
| 721 | |
| 722 | static void ip4_frags_ctl_register(void) |
| 723 | { |
| 724 | register_net_sysctl_rotable(net_ipv4_ctl_path, ip4_frags_ctl_table); |
| 725 | } |
| 726 | #else |
| 727 | static inline int ip4_frags_ns_ctl_register(struct net *net) |
| 728 | { |
| 729 | return 0; |
| 730 | } |
| 731 | |
| 732 | static inline void ip4_frags_ns_ctl_unregister(struct net *net) |
| 733 | { |
| 734 | } |
| 735 | |
| 736 | static inline void ip4_frags_ctl_register(void) |
| 737 | { |
| 738 | } |
| 739 | #endif |
| 740 | |
| 741 | static int __net_init ipv4_frags_init_net(struct net *net) |
| 742 | { |
| 743 | /* |
| 744 | * Fragment cache limits. We will commit 256K at one time. Should we |
| 745 | * cross that limit we will prune down to 192K. This should cope with |
| 746 | * even the most extreme cases without allowing an attacker to |
| 747 | * measurably harm machine performance. |
| 748 | */ |
| 749 | net->ipv4.frags.high_thresh = 256 * 1024; |
| 750 | net->ipv4.frags.low_thresh = 192 * 1024; |
| 751 | /* |
| 752 | * Important NOTE! Fragment queue must be destroyed before MSL expires. |
| 753 | * RFC791 is wrong proposing to prolongate timer each fragment arrival |
| 754 | * by TTL. |
| 755 | */ |
| 756 | net->ipv4.frags.timeout = IP_FRAG_TIME; |
| 757 | |
| 758 | inet_frags_init_net(&net->ipv4.frags); |
| 759 | |
| 760 | return ip4_frags_ns_ctl_register(net); |
| 761 | } |
| 762 | |
| 763 | static void __net_exit ipv4_frags_exit_net(struct net *net) |
| 764 | { |
| 765 | ip4_frags_ns_ctl_unregister(net); |
| 766 | inet_frags_exit_net(&net->ipv4.frags, &ip4_frags); |
| 767 | } |
| 768 | |
| 769 | static struct pernet_operations ip4_frags_ops = { |
| 770 | .init = ipv4_frags_init_net, |
| 771 | .exit = ipv4_frags_exit_net, |
| 772 | }; |
| 773 | |
| 774 | void __init ipfrag_init(void) |
| 775 | { |
| 776 | ip4_frags_ctl_register(); |
| 777 | register_pernet_subsys(&ip4_frags_ops); |
| 778 | ip4_frags.hashfn = ip4_hashfn; |
| 779 | ip4_frags.constructor = ip4_frag_init; |
| 780 | ip4_frags.destructor = ip4_frag_free; |
| 781 | ip4_frags.skb_free = NULL; |
| 782 | ip4_frags.qsize = sizeof(struct ipq); |
| 783 | ip4_frags.match = ip4_frag_match; |
| 784 | ip4_frags.frag_expire = ip_expire; |
| 785 | ip4_frags.secret_interval = 10 * 60 * HZ; |
| 786 | inet_frags_init(&ip4_frags); |
| 787 | } |
| 788 | |
| 789 | EXPORT_SYMBOL(ip_defrag); |