11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * INET An implementation of the TCP/IP protocol suite for the LINUX 31da177e4SLinus Torvalds * operating system. INET is implemented using the BSD Socket 41da177e4SLinus Torvalds * interface as the means of communication with the user level. 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * The IP fragmentation functionality. 71da177e4SLinus Torvalds * 81da177e4SLinus Torvalds * Version: $Id: ip_fragment.c,v 1.59 2002/01/12 07:54:56 davem Exp $ 91da177e4SLinus Torvalds * 101da177e4SLinus Torvalds * Authors: Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG> 111da177e4SLinus Torvalds * Alan Cox <Alan.Cox@linux.org> 121da177e4SLinus Torvalds * 131da177e4SLinus Torvalds * Fixes: 141da177e4SLinus Torvalds * Alan Cox : Split from ip.c , see ip_input.c for history. 151da177e4SLinus Torvalds * David S. Miller : Begin massive cleanup... 161da177e4SLinus Torvalds * Andi Kleen : Add sysctls. 171da177e4SLinus Torvalds * xxxx : Overlapfrag bug. 181da177e4SLinus Torvalds * Ultima : ip_expire() kernel panic. 191da177e4SLinus Torvalds * Bill Hawes : Frag accounting and evictor fixes. 201da177e4SLinus Torvalds * John McDonald : 0 length frag bug. 211da177e4SLinus Torvalds * Alexey Kuznetsov: SMP races, threading, cleanup. 221da177e4SLinus Torvalds * Patrick McHardy : LRU queue of frag heads for evictor. 231da177e4SLinus Torvalds */ 241da177e4SLinus Torvalds 2589cee8b1SHerbert Xu #include <linux/compiler.h> 261da177e4SLinus Torvalds #include <linux/module.h> 271da177e4SLinus Torvalds #include <linux/types.h> 281da177e4SLinus Torvalds #include <linux/mm.h> 291da177e4SLinus Torvalds #include <linux/jiffies.h> 301da177e4SLinus Torvalds #include <linux/skbuff.h> 311da177e4SLinus Torvalds #include <linux/list.h> 321da177e4SLinus Torvalds #include <linux/ip.h> 331da177e4SLinus Torvalds #include <linux/icmp.h> 341da177e4SLinus Torvalds #include <linux/netdevice.h> 351da177e4SLinus Torvalds #include <linux/jhash.h> 361da177e4SLinus Torvalds #include <linux/random.h> 371da177e4SLinus Torvalds #include <net/sock.h> 381da177e4SLinus Torvalds #include <net/ip.h> 391da177e4SLinus Torvalds #include <net/icmp.h> 401da177e4SLinus Torvalds #include <net/checksum.h> 4189cee8b1SHerbert Xu #include <net/inetpeer.h> 425ab11c98SPavel Emelyanov #include <net/inet_frag.h> 431da177e4SLinus Torvalds #include <linux/tcp.h> 441da177e4SLinus Torvalds #include <linux/udp.h> 451da177e4SLinus Torvalds #include <linux/inet.h> 461da177e4SLinus Torvalds #include <linux/netfilter_ipv4.h> 471da177e4SLinus Torvalds 481da177e4SLinus Torvalds /* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6 491da177e4SLinus Torvalds * code now. If you change something here, _PLEASE_ update ipv6/reassembly.c 501da177e4SLinus Torvalds * as well. Or notify me, at least. --ANK 511da177e4SLinus Torvalds */ 521da177e4SLinus Torvalds 538d8354d2SPavel Emelyanov static int sysctl_ipfrag_max_dist __read_mostly = 64; 5489cee8b1SHerbert Xu 551da177e4SLinus Torvalds struct ipfrag_skb_cb 561da177e4SLinus Torvalds { 571da177e4SLinus Torvalds struct inet_skb_parm h; 581da177e4SLinus Torvalds int offset; 591da177e4SLinus Torvalds }; 601da177e4SLinus Torvalds 611da177e4SLinus Torvalds #define FRAG_CB(skb) ((struct ipfrag_skb_cb*)((skb)->cb)) 621da177e4SLinus Torvalds 631da177e4SLinus Torvalds /* Describe an entry in the "incomplete datagrams" queue. */ 641da177e4SLinus Torvalds struct ipq { 655ab11c98SPavel Emelyanov struct inet_frag_queue q; 665ab11c98SPavel Emelyanov 671da177e4SLinus Torvalds u32 user; 6818277770SAl Viro __be32 saddr; 6918277770SAl Viro __be32 daddr; 7018277770SAl Viro __be16 id; 711da177e4SLinus Torvalds u8 protocol; 7289cee8b1SHerbert Xu int iif; 7389cee8b1SHerbert Xu unsigned int rid; 7489cee8b1SHerbert Xu struct inet_peer *peer; 751da177e4SLinus Torvalds }; 761da177e4SLinus Torvalds 778d8354d2SPavel Emelyanov static struct inet_frags_ctl ip4_frags_ctl __read_mostly = { 7804128f23SPavel Emelyanov /* 7904128f23SPavel Emelyanov * Fragment cache limits. We will commit 256K at one time. Should we 8004128f23SPavel Emelyanov * cross that limit we will prune down to 192K. This should cope with 8104128f23SPavel Emelyanov * even the most extreme cases without allowing an attacker to 8204128f23SPavel Emelyanov * measurably harm machine performance. 8304128f23SPavel Emelyanov */ 8404128f23SPavel Emelyanov .high_thresh = 256 * 1024, 8504128f23SPavel Emelyanov .low_thresh = 192 * 1024, 8604128f23SPavel Emelyanov .secret_interval = 10 * 60 * HZ, 8704128f23SPavel Emelyanov }; 8804128f23SPavel Emelyanov 897eb95156SPavel Emelyanov static struct inet_frags ip4_frags; 901da177e4SLinus Torvalds 91e5a2bb84SPavel Emelyanov int ip_frag_nqueues(struct net *net) 927eb95156SPavel Emelyanov { 93e5a2bb84SPavel Emelyanov return net->ipv4.frags.nqueues; 947eb95156SPavel Emelyanov } 951da177e4SLinus Torvalds 966ddc0822SPavel Emelyanov int ip_frag_mem(struct net *net) 977eb95156SPavel Emelyanov { 986ddc0822SPavel Emelyanov return atomic_read(&net->ipv4.frags.mem); 997eb95156SPavel Emelyanov } 1001da177e4SLinus Torvalds 1011706d587SHerbert Xu static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, 1021706d587SHerbert Xu struct net_device *dev); 1031706d587SHerbert Xu 104c6fda282SPavel Emelyanov struct ip4_create_arg { 105c6fda282SPavel Emelyanov struct iphdr *iph; 106c6fda282SPavel Emelyanov u32 user; 107c6fda282SPavel Emelyanov }; 108c6fda282SPavel Emelyanov 10918277770SAl Viro static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot) 1101da177e4SLinus Torvalds { 11118277770SAl Viro return jhash_3words((__force u32)id << 16 | prot, 11218277770SAl Viro (__force u32)saddr, (__force u32)daddr, 1137eb95156SPavel Emelyanov ip4_frags.rnd) & (INETFRAGS_HASHSZ - 1); 1141da177e4SLinus Torvalds } 1151da177e4SLinus Torvalds 116321a3a99SPavel Emelyanov static unsigned int ip4_hashfn(struct inet_frag_queue *q) 1171da177e4SLinus Torvalds { 118321a3a99SPavel Emelyanov struct ipq *ipq; 1191da177e4SLinus Torvalds 120321a3a99SPavel Emelyanov ipq = container_of(q, struct ipq, q); 121321a3a99SPavel Emelyanov return ipqhashfn(ipq->id, ipq->saddr, ipq->daddr, ipq->protocol); 1221da177e4SLinus Torvalds } 1231da177e4SLinus Torvalds 124abd6523dSPavel Emelyanov static int ip4_frag_match(struct inet_frag_queue *q, void *a) 125abd6523dSPavel Emelyanov { 126abd6523dSPavel Emelyanov struct ipq *qp; 127abd6523dSPavel Emelyanov struct ip4_create_arg *arg = a; 128abd6523dSPavel Emelyanov 129abd6523dSPavel Emelyanov qp = container_of(q, struct ipq, q); 130abd6523dSPavel Emelyanov return (qp->id == arg->iph->id && 131abd6523dSPavel Emelyanov qp->saddr == arg->iph->saddr && 132abd6523dSPavel Emelyanov qp->daddr == arg->iph->daddr && 133abd6523dSPavel Emelyanov qp->protocol == arg->iph->protocol && 134abd6523dSPavel Emelyanov qp->user == arg->user); 135abd6523dSPavel Emelyanov } 136abd6523dSPavel Emelyanov 1371da177e4SLinus Torvalds /* Memory Tracking Functions. */ 1386ddc0822SPavel Emelyanov static __inline__ void frag_kfree_skb(struct netns_frags *nf, 1396ddc0822SPavel Emelyanov struct sk_buff *skb, int *work) 1401da177e4SLinus Torvalds { 1411da177e4SLinus Torvalds if (work) 1421da177e4SLinus Torvalds *work -= skb->truesize; 1436ddc0822SPavel Emelyanov atomic_sub(skb->truesize, &nf->mem); 1441da177e4SLinus Torvalds kfree_skb(skb); 1451da177e4SLinus Torvalds } 1461da177e4SLinus Torvalds 147c6fda282SPavel Emelyanov static void ip4_frag_init(struct inet_frag_queue *q, void *a) 148c6fda282SPavel Emelyanov { 149c6fda282SPavel Emelyanov struct ipq *qp = container_of(q, struct ipq, q); 150c6fda282SPavel Emelyanov struct ip4_create_arg *arg = a; 151c6fda282SPavel Emelyanov 152c6fda282SPavel Emelyanov qp->protocol = arg->iph->protocol; 153c6fda282SPavel Emelyanov qp->id = arg->iph->id; 154c6fda282SPavel Emelyanov qp->saddr = arg->iph->saddr; 155c6fda282SPavel Emelyanov qp->daddr = arg->iph->daddr; 156c6fda282SPavel Emelyanov qp->user = arg->user; 157c6fda282SPavel Emelyanov qp->peer = sysctl_ipfrag_max_dist ? 158c6fda282SPavel Emelyanov inet_getpeer(arg->iph->saddr, 1) : NULL; 159c6fda282SPavel Emelyanov } 160c6fda282SPavel Emelyanov 1611e4b8287SPavel Emelyanov static __inline__ void ip4_frag_free(struct inet_frag_queue *q) 1621da177e4SLinus Torvalds { 1631e4b8287SPavel Emelyanov struct ipq *qp; 1641e4b8287SPavel Emelyanov 1651e4b8287SPavel Emelyanov qp = container_of(q, struct ipq, q); 1661e4b8287SPavel Emelyanov if (qp->peer) 1671e4b8287SPavel Emelyanov inet_putpeer(qp->peer); 1681da177e4SLinus Torvalds } 1691da177e4SLinus Torvalds 1701da177e4SLinus Torvalds 1711da177e4SLinus Torvalds /* Destruction primitives. */ 1721da177e4SLinus Torvalds 1734b6cb5d8SPavel Emelyanov static __inline__ void ipq_put(struct ipq *ipq) 1741da177e4SLinus Torvalds { 175762cc408SPavel Emelyanov inet_frag_put(&ipq->q, &ip4_frags); 1761da177e4SLinus Torvalds } 1771da177e4SLinus Torvalds 1781da177e4SLinus Torvalds /* Kill ipq entry. It is not destroyed immediately, 1791da177e4SLinus Torvalds * because caller (and someone more) holds reference count. 1801da177e4SLinus Torvalds */ 1811da177e4SLinus Torvalds static void ipq_kill(struct ipq *ipq) 1821da177e4SLinus Torvalds { 183277e650dSPavel Emelyanov inet_frag_kill(&ipq->q, &ip4_frags); 1841da177e4SLinus Torvalds } 1851da177e4SLinus Torvalds 1861da177e4SLinus Torvalds /* Memory limiting on fragments. Evictor trashes the oldest 1871da177e4SLinus Torvalds * fragment queue until we are back under the threshold. 1881da177e4SLinus Torvalds */ 1896ddc0822SPavel Emelyanov static void ip_evictor(struct net *net) 1901da177e4SLinus Torvalds { 1918e7999c4SPavel Emelyanov int evicted; 1921da177e4SLinus Torvalds 1936ddc0822SPavel Emelyanov evicted = inet_frag_evictor(&net->ipv4.frags, &ip4_frags); 1948e7999c4SPavel Emelyanov if (evicted) 1958e7999c4SPavel Emelyanov IP_ADD_STATS_BH(IPSTATS_MIB_REASMFAILS, evicted); 1961da177e4SLinus Torvalds } 1971da177e4SLinus Torvalds 1981da177e4SLinus Torvalds /* 1991da177e4SLinus Torvalds * Oops, a fragment queue timed out. Kill it and send an ICMP reply. 2001da177e4SLinus Torvalds */ 2011da177e4SLinus Torvalds static void ip_expire(unsigned long arg) 2021da177e4SLinus Torvalds { 203e521db9dSPavel Emelyanov struct ipq *qp; 204e521db9dSPavel Emelyanov 205e521db9dSPavel Emelyanov qp = container_of((struct inet_frag_queue *) arg, struct ipq, q); 2061da177e4SLinus Torvalds 2075ab11c98SPavel Emelyanov spin_lock(&qp->q.lock); 2081da177e4SLinus Torvalds 2095ab11c98SPavel Emelyanov if (qp->q.last_in & COMPLETE) 2101da177e4SLinus Torvalds goto out; 2111da177e4SLinus Torvalds 2121da177e4SLinus Torvalds ipq_kill(qp); 2131da177e4SLinus Torvalds 2141da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMTIMEOUT); 2151da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 2161da177e4SLinus Torvalds 2175ab11c98SPavel Emelyanov if ((qp->q.last_in&FIRST_IN) && qp->q.fragments != NULL) { 2185ab11c98SPavel Emelyanov struct sk_buff *head = qp->q.fragments; 2191da177e4SLinus Torvalds /* Send an ICMP "Fragment Reassembly Timeout" message. */ 220881d966bSEric W. Biederman if ((head->dev = dev_get_by_index(&init_net, qp->iif)) != NULL) { 2211da177e4SLinus Torvalds icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0); 2221da177e4SLinus Torvalds dev_put(head->dev); 2231da177e4SLinus Torvalds } 2241da177e4SLinus Torvalds } 2251da177e4SLinus Torvalds out: 2265ab11c98SPavel Emelyanov spin_unlock(&qp->q.lock); 2274b6cb5d8SPavel Emelyanov ipq_put(qp); 2281da177e4SLinus Torvalds } 2291da177e4SLinus Torvalds 230abd6523dSPavel Emelyanov /* Find the correct entry in the "incomplete datagrams" queue for 231abd6523dSPavel Emelyanov * this IP datagram, and create new one, if nothing is found. 232abd6523dSPavel Emelyanov */ 233ac18e750SPavel Emelyanov static inline struct ipq *ip_find(struct net *net, struct iphdr *iph, u32 user) 2341da177e4SLinus Torvalds { 235c6fda282SPavel Emelyanov struct inet_frag_queue *q; 236c6fda282SPavel Emelyanov struct ip4_create_arg arg; 237abd6523dSPavel Emelyanov unsigned int hash; 2381da177e4SLinus Torvalds 239c6fda282SPavel Emelyanov arg.iph = iph; 240c6fda282SPavel Emelyanov arg.user = user; 241abd6523dSPavel Emelyanov hash = ipqhashfn(iph->id, iph->saddr, iph->daddr, iph->protocol); 242c6fda282SPavel Emelyanov 243ac18e750SPavel Emelyanov q = inet_frag_find(&net->ipv4.frags, &ip4_frags, &arg, hash); 244c6fda282SPavel Emelyanov if (q == NULL) 2451da177e4SLinus Torvalds goto out_nomem; 2461da177e4SLinus Torvalds 247c6fda282SPavel Emelyanov return container_of(q, struct ipq, q); 2481da177e4SLinus Torvalds 2491da177e4SLinus Torvalds out_nomem: 25064ce2073SPatrick McHardy LIMIT_NETDEBUG(KERN_ERR "ip_frag_create: no memory left !\n"); 2511da177e4SLinus Torvalds return NULL; 2521da177e4SLinus Torvalds } 2531da177e4SLinus Torvalds 25489cee8b1SHerbert Xu /* Is the fragment too far ahead to be part of ipq? */ 25589cee8b1SHerbert Xu static inline int ip_frag_too_far(struct ipq *qp) 25689cee8b1SHerbert Xu { 25789cee8b1SHerbert Xu struct inet_peer *peer = qp->peer; 25889cee8b1SHerbert Xu unsigned int max = sysctl_ipfrag_max_dist; 25989cee8b1SHerbert Xu unsigned int start, end; 26089cee8b1SHerbert Xu 26189cee8b1SHerbert Xu int rc; 26289cee8b1SHerbert Xu 26389cee8b1SHerbert Xu if (!peer || !max) 26489cee8b1SHerbert Xu return 0; 26589cee8b1SHerbert Xu 26689cee8b1SHerbert Xu start = qp->rid; 26789cee8b1SHerbert Xu end = atomic_inc_return(&peer->rid); 26889cee8b1SHerbert Xu qp->rid = end; 26989cee8b1SHerbert Xu 2705ab11c98SPavel Emelyanov rc = qp->q.fragments && (end - start) > max; 27189cee8b1SHerbert Xu 27289cee8b1SHerbert Xu if (rc) { 27389cee8b1SHerbert Xu IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 27489cee8b1SHerbert Xu } 27589cee8b1SHerbert Xu 27689cee8b1SHerbert Xu return rc; 27789cee8b1SHerbert Xu } 27889cee8b1SHerbert Xu 27989cee8b1SHerbert Xu static int ip_frag_reinit(struct ipq *qp) 28089cee8b1SHerbert Xu { 28189cee8b1SHerbert Xu struct sk_buff *fp; 28289cee8b1SHerbert Xu 283b2fd5321SPavel Emelyanov if (!mod_timer(&qp->q.timer, jiffies + qp->q.net->timeout)) { 2845ab11c98SPavel Emelyanov atomic_inc(&qp->q.refcnt); 28589cee8b1SHerbert Xu return -ETIMEDOUT; 28689cee8b1SHerbert Xu } 28789cee8b1SHerbert Xu 2885ab11c98SPavel Emelyanov fp = qp->q.fragments; 28989cee8b1SHerbert Xu do { 29089cee8b1SHerbert Xu struct sk_buff *xp = fp->next; 2916ddc0822SPavel Emelyanov frag_kfree_skb(qp->q.net, fp, NULL); 29289cee8b1SHerbert Xu fp = xp; 29389cee8b1SHerbert Xu } while (fp); 29489cee8b1SHerbert Xu 2955ab11c98SPavel Emelyanov qp->q.last_in = 0; 2965ab11c98SPavel Emelyanov qp->q.len = 0; 2975ab11c98SPavel Emelyanov qp->q.meat = 0; 2985ab11c98SPavel Emelyanov qp->q.fragments = NULL; 29989cee8b1SHerbert Xu qp->iif = 0; 30089cee8b1SHerbert Xu 30189cee8b1SHerbert Xu return 0; 30289cee8b1SHerbert Xu } 30389cee8b1SHerbert Xu 3041da177e4SLinus Torvalds /* Add new segment to existing queue. */ 3051706d587SHerbert Xu static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) 3061da177e4SLinus Torvalds { 3071da177e4SLinus Torvalds struct sk_buff *prev, *next; 3081706d587SHerbert Xu struct net_device *dev; 3091da177e4SLinus Torvalds int flags, offset; 3101da177e4SLinus Torvalds int ihl, end; 3111706d587SHerbert Xu int err = -ENOENT; 3121da177e4SLinus Torvalds 3135ab11c98SPavel Emelyanov if (qp->q.last_in & COMPLETE) 3141da177e4SLinus Torvalds goto err; 3151da177e4SLinus Torvalds 31689cee8b1SHerbert Xu if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && 3171706d587SHerbert Xu unlikely(ip_frag_too_far(qp)) && 3181706d587SHerbert Xu unlikely(err = ip_frag_reinit(qp))) { 31989cee8b1SHerbert Xu ipq_kill(qp); 32089cee8b1SHerbert Xu goto err; 32189cee8b1SHerbert Xu } 32289cee8b1SHerbert Xu 323eddc9ec5SArnaldo Carvalho de Melo offset = ntohs(ip_hdr(skb)->frag_off); 3241da177e4SLinus Torvalds flags = offset & ~IP_OFFSET; 3251da177e4SLinus Torvalds offset &= IP_OFFSET; 3261da177e4SLinus Torvalds offset <<= 3; /* offset is in 8-byte chunks */ 327c9bdd4b5SArnaldo Carvalho de Melo ihl = ip_hdrlen(skb); 3281da177e4SLinus Torvalds 3291da177e4SLinus Torvalds /* Determine the position of this fragment. */ 3301da177e4SLinus Torvalds end = offset + skb->len - ihl; 3311706d587SHerbert Xu err = -EINVAL; 3321da177e4SLinus Torvalds 3331da177e4SLinus Torvalds /* Is this the final fragment? */ 3341da177e4SLinus Torvalds if ((flags & IP_MF) == 0) { 3351da177e4SLinus Torvalds /* If we already have some bits beyond end 3361da177e4SLinus Torvalds * or have different end, the segment is corrrupted. 3371da177e4SLinus Torvalds */ 3385ab11c98SPavel Emelyanov if (end < qp->q.len || 3395ab11c98SPavel Emelyanov ((qp->q.last_in & LAST_IN) && end != qp->q.len)) 3401da177e4SLinus Torvalds goto err; 3415ab11c98SPavel Emelyanov qp->q.last_in |= LAST_IN; 3425ab11c98SPavel Emelyanov qp->q.len = end; 3431da177e4SLinus Torvalds } else { 3441da177e4SLinus Torvalds if (end&7) { 3451da177e4SLinus Torvalds end &= ~7; 3461da177e4SLinus Torvalds if (skb->ip_summed != CHECKSUM_UNNECESSARY) 3471da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_NONE; 3481da177e4SLinus Torvalds } 3495ab11c98SPavel Emelyanov if (end > qp->q.len) { 3501da177e4SLinus Torvalds /* Some bits beyond end -> corruption. */ 3515ab11c98SPavel Emelyanov if (qp->q.last_in & LAST_IN) 3521da177e4SLinus Torvalds goto err; 3535ab11c98SPavel Emelyanov qp->q.len = end; 3541da177e4SLinus Torvalds } 3551da177e4SLinus Torvalds } 3561da177e4SLinus Torvalds if (end == offset) 3571da177e4SLinus Torvalds goto err; 3581da177e4SLinus Torvalds 3591706d587SHerbert Xu err = -ENOMEM; 3601da177e4SLinus Torvalds if (pskb_pull(skb, ihl) == NULL) 3611da177e4SLinus Torvalds goto err; 3621706d587SHerbert Xu 3631706d587SHerbert Xu err = pskb_trim_rcsum(skb, end - offset); 3641706d587SHerbert Xu if (err) 3651da177e4SLinus Torvalds goto err; 3661da177e4SLinus Torvalds 3671da177e4SLinus Torvalds /* Find out which fragments are in front and at the back of us 3681da177e4SLinus Torvalds * in the chain of fragments so far. We must know where to put 3691da177e4SLinus Torvalds * this fragment, right? 3701da177e4SLinus Torvalds */ 3711da177e4SLinus Torvalds prev = NULL; 3725ab11c98SPavel Emelyanov for (next = qp->q.fragments; next != NULL; next = next->next) { 3731da177e4SLinus Torvalds if (FRAG_CB(next)->offset >= offset) 3741da177e4SLinus Torvalds break; /* bingo! */ 3751da177e4SLinus Torvalds prev = next; 3761da177e4SLinus Torvalds } 3771da177e4SLinus Torvalds 3781da177e4SLinus Torvalds /* We found where to put this one. Check for overlap with 3791da177e4SLinus Torvalds * preceding fragment, and, if needed, align things so that 3801da177e4SLinus Torvalds * any overlaps are eliminated. 3811da177e4SLinus Torvalds */ 3821da177e4SLinus Torvalds if (prev) { 3831da177e4SLinus Torvalds int i = (FRAG_CB(prev)->offset + prev->len) - offset; 3841da177e4SLinus Torvalds 3851da177e4SLinus Torvalds if (i > 0) { 3861da177e4SLinus Torvalds offset += i; 3871706d587SHerbert Xu err = -EINVAL; 3881da177e4SLinus Torvalds if (end <= offset) 3891da177e4SLinus Torvalds goto err; 3901706d587SHerbert Xu err = -ENOMEM; 3911da177e4SLinus Torvalds if (!pskb_pull(skb, i)) 3921da177e4SLinus Torvalds goto err; 3931da177e4SLinus Torvalds if (skb->ip_summed != CHECKSUM_UNNECESSARY) 3941da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_NONE; 3951da177e4SLinus Torvalds } 3961da177e4SLinus Torvalds } 3971da177e4SLinus Torvalds 3981706d587SHerbert Xu err = -ENOMEM; 3991706d587SHerbert Xu 4001da177e4SLinus Torvalds while (next && FRAG_CB(next)->offset < end) { 4011da177e4SLinus Torvalds int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ 4021da177e4SLinus Torvalds 4031da177e4SLinus Torvalds if (i < next->len) { 4041da177e4SLinus Torvalds /* Eat head of the next overlapped fragment 4051da177e4SLinus Torvalds * and leave the loop. The next ones cannot overlap. 4061da177e4SLinus Torvalds */ 4071da177e4SLinus Torvalds if (!pskb_pull(next, i)) 4081da177e4SLinus Torvalds goto err; 4091da177e4SLinus Torvalds FRAG_CB(next)->offset += i; 4105ab11c98SPavel Emelyanov qp->q.meat -= i; 4111da177e4SLinus Torvalds if (next->ip_summed != CHECKSUM_UNNECESSARY) 4121da177e4SLinus Torvalds next->ip_summed = CHECKSUM_NONE; 4131da177e4SLinus Torvalds break; 4141da177e4SLinus Torvalds } else { 4151da177e4SLinus Torvalds struct sk_buff *free_it = next; 4161da177e4SLinus Torvalds 41747c6bf77SPeter Zijlstra /* Old fragment is completely overridden with 4181da177e4SLinus Torvalds * new one drop it. 4191da177e4SLinus Torvalds */ 4201da177e4SLinus Torvalds next = next->next; 4211da177e4SLinus Torvalds 4221da177e4SLinus Torvalds if (prev) 4231da177e4SLinus Torvalds prev->next = next; 4241da177e4SLinus Torvalds else 4255ab11c98SPavel Emelyanov qp->q.fragments = next; 4261da177e4SLinus Torvalds 4275ab11c98SPavel Emelyanov qp->q.meat -= free_it->len; 4286ddc0822SPavel Emelyanov frag_kfree_skb(qp->q.net, free_it, NULL); 4291da177e4SLinus Torvalds } 4301da177e4SLinus Torvalds } 4311da177e4SLinus Torvalds 4321da177e4SLinus Torvalds FRAG_CB(skb)->offset = offset; 4331da177e4SLinus Torvalds 4341da177e4SLinus Torvalds /* Insert this fragment in the chain of fragments. */ 4351da177e4SLinus Torvalds skb->next = next; 4361da177e4SLinus Torvalds if (prev) 4371da177e4SLinus Torvalds prev->next = skb; 4381da177e4SLinus Torvalds else 4395ab11c98SPavel Emelyanov qp->q.fragments = skb; 4401da177e4SLinus Torvalds 4411706d587SHerbert Xu dev = skb->dev; 4421706d587SHerbert Xu if (dev) { 4431706d587SHerbert Xu qp->iif = dev->ifindex; 4441da177e4SLinus Torvalds skb->dev = NULL; 4451706d587SHerbert Xu } 4465ab11c98SPavel Emelyanov qp->q.stamp = skb->tstamp; 4475ab11c98SPavel Emelyanov qp->q.meat += skb->len; 4486ddc0822SPavel Emelyanov atomic_add(skb->truesize, &qp->q.net->mem); 4491da177e4SLinus Torvalds if (offset == 0) 4505ab11c98SPavel Emelyanov qp->q.last_in |= FIRST_IN; 4511da177e4SLinus Torvalds 4525ab11c98SPavel Emelyanov if (qp->q.last_in == (FIRST_IN | LAST_IN) && qp->q.meat == qp->q.len) 4531706d587SHerbert Xu return ip_frag_reasm(qp, prev, dev); 4541706d587SHerbert Xu 4557eb95156SPavel Emelyanov write_lock(&ip4_frags.lock); 4567eb95156SPavel Emelyanov list_move_tail(&qp->q.lru_list, &ip4_frags.lru_list); 4577eb95156SPavel Emelyanov write_unlock(&ip4_frags.lock); 4581706d587SHerbert Xu return -EINPROGRESS; 4591da177e4SLinus Torvalds 4601da177e4SLinus Torvalds err: 4611da177e4SLinus Torvalds kfree_skb(skb); 4621706d587SHerbert Xu return err; 4631da177e4SLinus Torvalds } 4641da177e4SLinus Torvalds 4651da177e4SLinus Torvalds 4661da177e4SLinus Torvalds /* Build a new IP datagram from all its fragments. */ 4671da177e4SLinus Torvalds 4681706d587SHerbert Xu static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, 4691706d587SHerbert Xu struct net_device *dev) 4701da177e4SLinus Torvalds { 4711da177e4SLinus Torvalds struct iphdr *iph; 4725ab11c98SPavel Emelyanov struct sk_buff *fp, *head = qp->q.fragments; 4731da177e4SLinus Torvalds int len; 4741da177e4SLinus Torvalds int ihlen; 4751706d587SHerbert Xu int err; 4761da177e4SLinus Torvalds 4771da177e4SLinus Torvalds ipq_kill(qp); 4781da177e4SLinus Torvalds 4791706d587SHerbert Xu /* Make the one we just received the head. */ 4801706d587SHerbert Xu if (prev) { 4811706d587SHerbert Xu head = prev->next; 4821706d587SHerbert Xu fp = skb_clone(head, GFP_ATOMIC); 4831706d587SHerbert Xu if (!fp) 4841706d587SHerbert Xu goto out_nomem; 4851706d587SHerbert Xu 4861706d587SHerbert Xu fp->next = head->next; 4871706d587SHerbert Xu prev->next = fp; 4881706d587SHerbert Xu 4895ab11c98SPavel Emelyanov skb_morph(head, qp->q.fragments); 4905ab11c98SPavel Emelyanov head->next = qp->q.fragments->next; 4911706d587SHerbert Xu 4925ab11c98SPavel Emelyanov kfree_skb(qp->q.fragments); 4935ab11c98SPavel Emelyanov qp->q.fragments = head; 4941706d587SHerbert Xu } 4951706d587SHerbert Xu 4961da177e4SLinus Torvalds BUG_TRAP(head != NULL); 4971da177e4SLinus Torvalds BUG_TRAP(FRAG_CB(head)->offset == 0); 4981da177e4SLinus Torvalds 4991da177e4SLinus Torvalds /* Allocate a new buffer for the datagram. */ 500c9bdd4b5SArnaldo Carvalho de Melo ihlen = ip_hdrlen(head); 5015ab11c98SPavel Emelyanov len = ihlen + qp->q.len; 5021da177e4SLinus Torvalds 5031706d587SHerbert Xu err = -E2BIG; 5041da177e4SLinus Torvalds if (len > 65535) 5051da177e4SLinus Torvalds goto out_oversize; 5061da177e4SLinus Torvalds 5071da177e4SLinus Torvalds /* Head of list must not be cloned. */ 5081da177e4SLinus Torvalds if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) 5091da177e4SLinus Torvalds goto out_nomem; 5101da177e4SLinus Torvalds 5111da177e4SLinus Torvalds /* If the first fragment is fragmented itself, we split 5121da177e4SLinus Torvalds * it to two chunks: the first with data and paged part 5131da177e4SLinus Torvalds * and the second, holding only fragments. */ 5141da177e4SLinus Torvalds if (skb_shinfo(head)->frag_list) { 5151da177e4SLinus Torvalds struct sk_buff *clone; 5161da177e4SLinus Torvalds int i, plen = 0; 5171da177e4SLinus Torvalds 5181da177e4SLinus Torvalds if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) 5191da177e4SLinus Torvalds goto out_nomem; 5201da177e4SLinus Torvalds clone->next = head->next; 5211da177e4SLinus Torvalds head->next = clone; 5221da177e4SLinus Torvalds skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; 5231da177e4SLinus Torvalds skb_shinfo(head)->frag_list = NULL; 5241da177e4SLinus Torvalds for (i=0; i<skb_shinfo(head)->nr_frags; i++) 5251da177e4SLinus Torvalds plen += skb_shinfo(head)->frags[i].size; 5261da177e4SLinus Torvalds clone->len = clone->data_len = head->data_len - plen; 5271da177e4SLinus Torvalds head->data_len -= clone->len; 5281da177e4SLinus Torvalds head->len -= clone->len; 5291da177e4SLinus Torvalds clone->csum = 0; 5301da177e4SLinus Torvalds clone->ip_summed = head->ip_summed; 5316ddc0822SPavel Emelyanov atomic_add(clone->truesize, &qp->q.net->mem); 5321da177e4SLinus Torvalds } 5331da177e4SLinus Torvalds 5341da177e4SLinus Torvalds skb_shinfo(head)->frag_list = head->next; 535d56f90a7SArnaldo Carvalho de Melo skb_push(head, head->data - skb_network_header(head)); 5366ddc0822SPavel Emelyanov atomic_sub(head->truesize, &qp->q.net->mem); 5371da177e4SLinus Torvalds 5381da177e4SLinus Torvalds for (fp=head->next; fp; fp = fp->next) { 5391da177e4SLinus Torvalds head->data_len += fp->len; 5401da177e4SLinus Torvalds head->len += fp->len; 5411da177e4SLinus Torvalds if (head->ip_summed != fp->ip_summed) 5421da177e4SLinus Torvalds head->ip_summed = CHECKSUM_NONE; 54384fa7933SPatrick McHardy else if (head->ip_summed == CHECKSUM_COMPLETE) 5441da177e4SLinus Torvalds head->csum = csum_add(head->csum, fp->csum); 5451da177e4SLinus Torvalds head->truesize += fp->truesize; 5466ddc0822SPavel Emelyanov atomic_sub(fp->truesize, &qp->q.net->mem); 5471da177e4SLinus Torvalds } 5481da177e4SLinus Torvalds 5491da177e4SLinus Torvalds head->next = NULL; 5501da177e4SLinus Torvalds head->dev = dev; 5515ab11c98SPavel Emelyanov head->tstamp = qp->q.stamp; 5521da177e4SLinus Torvalds 553eddc9ec5SArnaldo Carvalho de Melo iph = ip_hdr(head); 5541da177e4SLinus Torvalds iph->frag_off = 0; 5551da177e4SLinus Torvalds iph->tot_len = htons(len); 5561da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMOKS); 5575ab11c98SPavel Emelyanov qp->q.fragments = NULL; 5581706d587SHerbert Xu return 0; 5591da177e4SLinus Torvalds 5601da177e4SLinus Torvalds out_nomem: 56164ce2073SPatrick McHardy LIMIT_NETDEBUG(KERN_ERR "IP: queue_glue: no memory for gluing " 56264ce2073SPatrick McHardy "queue %p\n", qp); 56345542479SDavid Howells err = -ENOMEM; 5641da177e4SLinus Torvalds goto out_fail; 5651da177e4SLinus Torvalds out_oversize: 5661da177e4SLinus Torvalds if (net_ratelimit()) 5671da177e4SLinus Torvalds printk(KERN_INFO 5681da177e4SLinus Torvalds "Oversized IP packet from %d.%d.%d.%d.\n", 5691da177e4SLinus Torvalds NIPQUAD(qp->saddr)); 5701da177e4SLinus Torvalds out_fail: 5711da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 5721706d587SHerbert Xu return err; 5731da177e4SLinus Torvalds } 5741da177e4SLinus Torvalds 5751da177e4SLinus Torvalds /* Process an incoming IP datagram fragment. */ 576776c729eSHerbert Xu int ip_defrag(struct sk_buff *skb, u32 user) 5771da177e4SLinus Torvalds { 5781da177e4SLinus Torvalds struct ipq *qp; 579ac18e750SPavel Emelyanov struct net *net; 5801da177e4SLinus Torvalds 5811da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMREQDS); 5821da177e4SLinus Torvalds 583ac18e750SPavel Emelyanov net = skb->dev->nd_net; 5841da177e4SLinus Torvalds /* Start by cleaning up the memory. */ 5856ddc0822SPavel Emelyanov if (atomic_read(&net->ipv4.frags.mem) > ip4_frags_ctl.high_thresh) 5866ddc0822SPavel Emelyanov ip_evictor(net); 5871da177e4SLinus Torvalds 5881da177e4SLinus Torvalds /* Lookup (or create) queue header */ 589ac18e750SPavel Emelyanov if ((qp = ip_find(net, ip_hdr(skb), user)) != NULL) { 5901706d587SHerbert Xu int ret; 5911da177e4SLinus Torvalds 5925ab11c98SPavel Emelyanov spin_lock(&qp->q.lock); 5931da177e4SLinus Torvalds 5941706d587SHerbert Xu ret = ip_frag_queue(qp, skb); 5951da177e4SLinus Torvalds 5965ab11c98SPavel Emelyanov spin_unlock(&qp->q.lock); 5974b6cb5d8SPavel Emelyanov ipq_put(qp); 598776c729eSHerbert Xu return ret; 5991da177e4SLinus Torvalds } 6001da177e4SLinus Torvalds 6011da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 6021da177e4SLinus Torvalds kfree_skb(skb); 603776c729eSHerbert Xu return -ENOMEM; 6041da177e4SLinus Torvalds } 6051da177e4SLinus Torvalds 6068d8354d2SPavel Emelyanov #ifdef CONFIG_SYSCTL 6078d8354d2SPavel Emelyanov static int zero; 6088d8354d2SPavel Emelyanov 6098d8354d2SPavel Emelyanov static struct ctl_table ip4_frags_ctl_table[] = { 6108d8354d2SPavel Emelyanov { 6118d8354d2SPavel Emelyanov .ctl_name = NET_IPV4_IPFRAG_HIGH_THRESH, 6128d8354d2SPavel Emelyanov .procname = "ipfrag_high_thresh", 6138d8354d2SPavel Emelyanov .data = &ip4_frags_ctl.high_thresh, 6148d8354d2SPavel Emelyanov .maxlen = sizeof(int), 6158d8354d2SPavel Emelyanov .mode = 0644, 6168d8354d2SPavel Emelyanov .proc_handler = &proc_dointvec 6178d8354d2SPavel Emelyanov }, 6188d8354d2SPavel Emelyanov { 6198d8354d2SPavel Emelyanov .ctl_name = NET_IPV4_IPFRAG_LOW_THRESH, 6208d8354d2SPavel Emelyanov .procname = "ipfrag_low_thresh", 6218d8354d2SPavel Emelyanov .data = &ip4_frags_ctl.low_thresh, 6228d8354d2SPavel Emelyanov .maxlen = sizeof(int), 6238d8354d2SPavel Emelyanov .mode = 0644, 6248d8354d2SPavel Emelyanov .proc_handler = &proc_dointvec 6258d8354d2SPavel Emelyanov }, 6268d8354d2SPavel Emelyanov { 6278d8354d2SPavel Emelyanov .ctl_name = NET_IPV4_IPFRAG_TIME, 6288d8354d2SPavel Emelyanov .procname = "ipfrag_time", 629b2fd5321SPavel Emelyanov .data = &init_net.ipv4.frags.timeout, 6308d8354d2SPavel Emelyanov .maxlen = sizeof(int), 6318d8354d2SPavel Emelyanov .mode = 0644, 6328d8354d2SPavel Emelyanov .proc_handler = &proc_dointvec_jiffies, 6338d8354d2SPavel Emelyanov .strategy = &sysctl_jiffies 6348d8354d2SPavel Emelyanov }, 6358d8354d2SPavel Emelyanov { 6368d8354d2SPavel Emelyanov .ctl_name = NET_IPV4_IPFRAG_SECRET_INTERVAL, 6378d8354d2SPavel Emelyanov .procname = "ipfrag_secret_interval", 6388d8354d2SPavel Emelyanov .data = &ip4_frags_ctl.secret_interval, 6398d8354d2SPavel Emelyanov .maxlen = sizeof(int), 6408d8354d2SPavel Emelyanov .mode = 0644, 6418d8354d2SPavel Emelyanov .proc_handler = &proc_dointvec_jiffies, 6428d8354d2SPavel Emelyanov .strategy = &sysctl_jiffies 6438d8354d2SPavel Emelyanov }, 6448d8354d2SPavel Emelyanov { 6458d8354d2SPavel Emelyanov .procname = "ipfrag_max_dist", 6468d8354d2SPavel Emelyanov .data = &sysctl_ipfrag_max_dist, 6478d8354d2SPavel Emelyanov .maxlen = sizeof(int), 6488d8354d2SPavel Emelyanov .mode = 0644, 6498d8354d2SPavel Emelyanov .proc_handler = &proc_dointvec_minmax, 6508d8354d2SPavel Emelyanov .extra1 = &zero 6518d8354d2SPavel Emelyanov }, 6528d8354d2SPavel Emelyanov { } 6538d8354d2SPavel Emelyanov }; 6548d8354d2SPavel Emelyanov 6558d8354d2SPavel Emelyanov static int ip4_frags_ctl_register(struct net *net) 6568d8354d2SPavel Emelyanov { 657e4a2d5c2SPavel Emelyanov struct ctl_table *table; 6588d8354d2SPavel Emelyanov struct ctl_table_header *hdr; 6598d8354d2SPavel Emelyanov 660e4a2d5c2SPavel Emelyanov table = ip4_frags_ctl_table; 661e4a2d5c2SPavel Emelyanov if (net != &init_net) { 662e4a2d5c2SPavel Emelyanov table = kmemdup(table, sizeof(ip4_frags_ctl_table), GFP_KERNEL); 663e4a2d5c2SPavel Emelyanov if (table == NULL) 664e4a2d5c2SPavel Emelyanov goto err_alloc; 665e4a2d5c2SPavel Emelyanov 666e4a2d5c2SPavel Emelyanov table[0].mode &= ~0222; 667e4a2d5c2SPavel Emelyanov table[1].mode &= ~0222; 668b2fd5321SPavel Emelyanov table[2].data = &net->ipv4.frags.timeout; 669e4a2d5c2SPavel Emelyanov table[3].mode &= ~0222; 670e4a2d5c2SPavel Emelyanov table[4].mode &= ~0222; 671e4a2d5c2SPavel Emelyanov } 672e4a2d5c2SPavel Emelyanov 673e4a2d5c2SPavel Emelyanov hdr = register_net_sysctl_table(net, net_ipv4_ctl_path, table); 674e4a2d5c2SPavel Emelyanov if (hdr == NULL) 675e4a2d5c2SPavel Emelyanov goto err_reg; 676e4a2d5c2SPavel Emelyanov 677e4a2d5c2SPavel Emelyanov net->ipv4.frags_hdr = hdr; 678e4a2d5c2SPavel Emelyanov return 0; 679e4a2d5c2SPavel Emelyanov 680e4a2d5c2SPavel Emelyanov err_reg: 681e4a2d5c2SPavel Emelyanov if (net != &init_net) 682e4a2d5c2SPavel Emelyanov kfree(table); 683e4a2d5c2SPavel Emelyanov err_alloc: 684e4a2d5c2SPavel Emelyanov return -ENOMEM; 685e4a2d5c2SPavel Emelyanov } 686e4a2d5c2SPavel Emelyanov 687e4a2d5c2SPavel Emelyanov static void ip4_frags_ctl_unregister(struct net *net) 688e4a2d5c2SPavel Emelyanov { 689e4a2d5c2SPavel Emelyanov struct ctl_table *table; 690e4a2d5c2SPavel Emelyanov 691e4a2d5c2SPavel Emelyanov table = net->ipv4.frags_hdr->ctl_table_arg; 692e4a2d5c2SPavel Emelyanov unregister_net_sysctl_table(net->ipv4.frags_hdr); 693e4a2d5c2SPavel Emelyanov kfree(table); 6948d8354d2SPavel Emelyanov } 6958d8354d2SPavel Emelyanov #else 6968d8354d2SPavel Emelyanov static inline int ip4_frags_ctl_register(struct net *net) 6978d8354d2SPavel Emelyanov { 6988d8354d2SPavel Emelyanov return 0; 6998d8354d2SPavel Emelyanov } 700e4a2d5c2SPavel Emelyanov 701e4a2d5c2SPavel Emelyanov static inline void ip4_frags_ctl_unregister(struct net *net) 702e4a2d5c2SPavel Emelyanov { 703e4a2d5c2SPavel Emelyanov } 7048d8354d2SPavel Emelyanov #endif 7058d8354d2SPavel Emelyanov 7068d8354d2SPavel Emelyanov static int ipv4_frags_init_net(struct net *net) 7078d8354d2SPavel Emelyanov { 708b2fd5321SPavel Emelyanov /* 709b2fd5321SPavel Emelyanov * Important NOTE! Fragment queue must be destroyed before MSL expires. 710b2fd5321SPavel Emelyanov * RFC791 is wrong proposing to prolongate timer each fragment arrival 711b2fd5321SPavel Emelyanov * by TTL. 712b2fd5321SPavel Emelyanov */ 713b2fd5321SPavel Emelyanov net->ipv4.frags.timeout = IP_FRAG_TIME; 714b2fd5321SPavel Emelyanov 715e5a2bb84SPavel Emelyanov inet_frags_init_net(&net->ipv4.frags); 716e5a2bb84SPavel Emelyanov 7178d8354d2SPavel Emelyanov return ip4_frags_ctl_register(net); 7188d8354d2SPavel Emelyanov } 7198d8354d2SPavel Emelyanov 720b7aa0bf7SEric Dumazet void __init ipfrag_init(void) 7211da177e4SLinus Torvalds { 7228d8354d2SPavel Emelyanov ipv4_frags_init_net(&init_net); 72304128f23SPavel Emelyanov ip4_frags.ctl = &ip4_frags_ctl; 724321a3a99SPavel Emelyanov ip4_frags.hashfn = ip4_hashfn; 725c6fda282SPavel Emelyanov ip4_frags.constructor = ip4_frag_init; 7261e4b8287SPavel Emelyanov ip4_frags.destructor = ip4_frag_free; 7271e4b8287SPavel Emelyanov ip4_frags.skb_free = NULL; 7281e4b8287SPavel Emelyanov ip4_frags.qsize = sizeof(struct ipq); 729abd6523dSPavel Emelyanov ip4_frags.match = ip4_frag_match; 730e521db9dSPavel Emelyanov ip4_frags.frag_expire = ip_expire; 7317eb95156SPavel Emelyanov inet_frags_init(&ip4_frags); 7321da177e4SLinus Torvalds } 7331da177e4SLinus Torvalds 7341da177e4SLinus Torvalds EXPORT_SYMBOL(ip_defrag); 735