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 8704128f23SPavel Emelyanov /* 8804128f23SPavel Emelyanov * Important NOTE! Fragment queue must be destroyed before MSL expires. 8904128f23SPavel Emelyanov * RFC791 is wrong proposing to prolongate timer each fragment arrival 9004128f23SPavel Emelyanov * by TTL. 9104128f23SPavel Emelyanov */ 9204128f23SPavel Emelyanov .timeout = IP_FRAG_TIME, 9304128f23SPavel Emelyanov .secret_interval = 10 * 60 * HZ, 9404128f23SPavel Emelyanov }; 9504128f23SPavel Emelyanov 967eb95156SPavel Emelyanov static struct inet_frags ip4_frags; 971da177e4SLinus Torvalds 98e5a2bb84SPavel Emelyanov int ip_frag_nqueues(struct net *net) 997eb95156SPavel Emelyanov { 100e5a2bb84SPavel Emelyanov return net->ipv4.frags.nqueues; 1017eb95156SPavel Emelyanov } 1021da177e4SLinus Torvalds 103*6ddc0822SPavel Emelyanov int ip_frag_mem(struct net *net) 1047eb95156SPavel Emelyanov { 105*6ddc0822SPavel Emelyanov return atomic_read(&net->ipv4.frags.mem); 1067eb95156SPavel Emelyanov } 1071da177e4SLinus Torvalds 1081706d587SHerbert Xu static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, 1091706d587SHerbert Xu struct net_device *dev); 1101706d587SHerbert Xu 111c6fda282SPavel Emelyanov struct ip4_create_arg { 112c6fda282SPavel Emelyanov struct iphdr *iph; 113c6fda282SPavel Emelyanov u32 user; 114c6fda282SPavel Emelyanov }; 115c6fda282SPavel Emelyanov 11618277770SAl Viro static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot) 1171da177e4SLinus Torvalds { 11818277770SAl Viro return jhash_3words((__force u32)id << 16 | prot, 11918277770SAl Viro (__force u32)saddr, (__force u32)daddr, 1207eb95156SPavel Emelyanov ip4_frags.rnd) & (INETFRAGS_HASHSZ - 1); 1211da177e4SLinus Torvalds } 1221da177e4SLinus Torvalds 123321a3a99SPavel Emelyanov static unsigned int ip4_hashfn(struct inet_frag_queue *q) 1241da177e4SLinus Torvalds { 125321a3a99SPavel Emelyanov struct ipq *ipq; 1261da177e4SLinus Torvalds 127321a3a99SPavel Emelyanov ipq = container_of(q, struct ipq, q); 128321a3a99SPavel Emelyanov return ipqhashfn(ipq->id, ipq->saddr, ipq->daddr, ipq->protocol); 1291da177e4SLinus Torvalds } 1301da177e4SLinus Torvalds 131abd6523dSPavel Emelyanov static int ip4_frag_match(struct inet_frag_queue *q, void *a) 132abd6523dSPavel Emelyanov { 133abd6523dSPavel Emelyanov struct ipq *qp; 134abd6523dSPavel Emelyanov struct ip4_create_arg *arg = a; 135abd6523dSPavel Emelyanov 136abd6523dSPavel Emelyanov qp = container_of(q, struct ipq, q); 137abd6523dSPavel Emelyanov return (qp->id == arg->iph->id && 138abd6523dSPavel Emelyanov qp->saddr == arg->iph->saddr && 139abd6523dSPavel Emelyanov qp->daddr == arg->iph->daddr && 140abd6523dSPavel Emelyanov qp->protocol == arg->iph->protocol && 141abd6523dSPavel Emelyanov qp->user == arg->user); 142abd6523dSPavel Emelyanov } 143abd6523dSPavel Emelyanov 1441da177e4SLinus Torvalds /* Memory Tracking Functions. */ 145*6ddc0822SPavel Emelyanov static __inline__ void frag_kfree_skb(struct netns_frags *nf, 146*6ddc0822SPavel Emelyanov struct sk_buff *skb, int *work) 1471da177e4SLinus Torvalds { 1481da177e4SLinus Torvalds if (work) 1491da177e4SLinus Torvalds *work -= skb->truesize; 150*6ddc0822SPavel Emelyanov atomic_sub(skb->truesize, &nf->mem); 1511da177e4SLinus Torvalds kfree_skb(skb); 1521da177e4SLinus Torvalds } 1531da177e4SLinus Torvalds 154c6fda282SPavel Emelyanov static void ip4_frag_init(struct inet_frag_queue *q, void *a) 155c6fda282SPavel Emelyanov { 156c6fda282SPavel Emelyanov struct ipq *qp = container_of(q, struct ipq, q); 157c6fda282SPavel Emelyanov struct ip4_create_arg *arg = a; 158c6fda282SPavel Emelyanov 159c6fda282SPavel Emelyanov qp->protocol = arg->iph->protocol; 160c6fda282SPavel Emelyanov qp->id = arg->iph->id; 161c6fda282SPavel Emelyanov qp->saddr = arg->iph->saddr; 162c6fda282SPavel Emelyanov qp->daddr = arg->iph->daddr; 163c6fda282SPavel Emelyanov qp->user = arg->user; 164c6fda282SPavel Emelyanov qp->peer = sysctl_ipfrag_max_dist ? 165c6fda282SPavel Emelyanov inet_getpeer(arg->iph->saddr, 1) : NULL; 166c6fda282SPavel Emelyanov } 167c6fda282SPavel Emelyanov 1681e4b8287SPavel Emelyanov static __inline__ void ip4_frag_free(struct inet_frag_queue *q) 1691da177e4SLinus Torvalds { 1701e4b8287SPavel Emelyanov struct ipq *qp; 1711e4b8287SPavel Emelyanov 1721e4b8287SPavel Emelyanov qp = container_of(q, struct ipq, q); 1731e4b8287SPavel Emelyanov if (qp->peer) 1741e4b8287SPavel Emelyanov inet_putpeer(qp->peer); 1751da177e4SLinus Torvalds } 1761da177e4SLinus Torvalds 1771da177e4SLinus Torvalds 1781da177e4SLinus Torvalds /* Destruction primitives. */ 1791da177e4SLinus Torvalds 1804b6cb5d8SPavel Emelyanov static __inline__ void ipq_put(struct ipq *ipq) 1811da177e4SLinus Torvalds { 182762cc408SPavel Emelyanov inet_frag_put(&ipq->q, &ip4_frags); 1831da177e4SLinus Torvalds } 1841da177e4SLinus Torvalds 1851da177e4SLinus Torvalds /* Kill ipq entry. It is not destroyed immediately, 1861da177e4SLinus Torvalds * because caller (and someone more) holds reference count. 1871da177e4SLinus Torvalds */ 1881da177e4SLinus Torvalds static void ipq_kill(struct ipq *ipq) 1891da177e4SLinus Torvalds { 190277e650dSPavel Emelyanov inet_frag_kill(&ipq->q, &ip4_frags); 1911da177e4SLinus Torvalds } 1921da177e4SLinus Torvalds 1931da177e4SLinus Torvalds /* Memory limiting on fragments. Evictor trashes the oldest 1941da177e4SLinus Torvalds * fragment queue until we are back under the threshold. 1951da177e4SLinus Torvalds */ 196*6ddc0822SPavel Emelyanov static void ip_evictor(struct net *net) 1971da177e4SLinus Torvalds { 1988e7999c4SPavel Emelyanov int evicted; 1991da177e4SLinus Torvalds 200*6ddc0822SPavel Emelyanov evicted = inet_frag_evictor(&net->ipv4.frags, &ip4_frags); 2018e7999c4SPavel Emelyanov if (evicted) 2028e7999c4SPavel Emelyanov IP_ADD_STATS_BH(IPSTATS_MIB_REASMFAILS, evicted); 2031da177e4SLinus Torvalds } 2041da177e4SLinus Torvalds 2051da177e4SLinus Torvalds /* 2061da177e4SLinus Torvalds * Oops, a fragment queue timed out. Kill it and send an ICMP reply. 2071da177e4SLinus Torvalds */ 2081da177e4SLinus Torvalds static void ip_expire(unsigned long arg) 2091da177e4SLinus Torvalds { 210e521db9dSPavel Emelyanov struct ipq *qp; 211e521db9dSPavel Emelyanov 212e521db9dSPavel Emelyanov qp = container_of((struct inet_frag_queue *) arg, struct ipq, q); 2131da177e4SLinus Torvalds 2145ab11c98SPavel Emelyanov spin_lock(&qp->q.lock); 2151da177e4SLinus Torvalds 2165ab11c98SPavel Emelyanov if (qp->q.last_in & COMPLETE) 2171da177e4SLinus Torvalds goto out; 2181da177e4SLinus Torvalds 2191da177e4SLinus Torvalds ipq_kill(qp); 2201da177e4SLinus Torvalds 2211da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMTIMEOUT); 2221da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 2231da177e4SLinus Torvalds 2245ab11c98SPavel Emelyanov if ((qp->q.last_in&FIRST_IN) && qp->q.fragments != NULL) { 2255ab11c98SPavel Emelyanov struct sk_buff *head = qp->q.fragments; 2261da177e4SLinus Torvalds /* Send an ICMP "Fragment Reassembly Timeout" message. */ 227881d966bSEric W. Biederman if ((head->dev = dev_get_by_index(&init_net, qp->iif)) != NULL) { 2281da177e4SLinus Torvalds icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0); 2291da177e4SLinus Torvalds dev_put(head->dev); 2301da177e4SLinus Torvalds } 2311da177e4SLinus Torvalds } 2321da177e4SLinus Torvalds out: 2335ab11c98SPavel Emelyanov spin_unlock(&qp->q.lock); 2344b6cb5d8SPavel Emelyanov ipq_put(qp); 2351da177e4SLinus Torvalds } 2361da177e4SLinus Torvalds 237abd6523dSPavel Emelyanov /* Find the correct entry in the "incomplete datagrams" queue for 238abd6523dSPavel Emelyanov * this IP datagram, and create new one, if nothing is found. 239abd6523dSPavel Emelyanov */ 240ac18e750SPavel Emelyanov static inline struct ipq *ip_find(struct net *net, struct iphdr *iph, u32 user) 2411da177e4SLinus Torvalds { 242c6fda282SPavel Emelyanov struct inet_frag_queue *q; 243c6fda282SPavel Emelyanov struct ip4_create_arg arg; 244abd6523dSPavel Emelyanov unsigned int hash; 2451da177e4SLinus Torvalds 246c6fda282SPavel Emelyanov arg.iph = iph; 247c6fda282SPavel Emelyanov arg.user = user; 248abd6523dSPavel Emelyanov hash = ipqhashfn(iph->id, iph->saddr, iph->daddr, iph->protocol); 249c6fda282SPavel Emelyanov 250ac18e750SPavel Emelyanov q = inet_frag_find(&net->ipv4.frags, &ip4_frags, &arg, hash); 251c6fda282SPavel Emelyanov if (q == NULL) 2521da177e4SLinus Torvalds goto out_nomem; 2531da177e4SLinus Torvalds 254c6fda282SPavel Emelyanov return container_of(q, struct ipq, q); 2551da177e4SLinus Torvalds 2561da177e4SLinus Torvalds out_nomem: 25764ce2073SPatrick McHardy LIMIT_NETDEBUG(KERN_ERR "ip_frag_create: no memory left !\n"); 2581da177e4SLinus Torvalds return NULL; 2591da177e4SLinus Torvalds } 2601da177e4SLinus Torvalds 26189cee8b1SHerbert Xu /* Is the fragment too far ahead to be part of ipq? */ 26289cee8b1SHerbert Xu static inline int ip_frag_too_far(struct ipq *qp) 26389cee8b1SHerbert Xu { 26489cee8b1SHerbert Xu struct inet_peer *peer = qp->peer; 26589cee8b1SHerbert Xu unsigned int max = sysctl_ipfrag_max_dist; 26689cee8b1SHerbert Xu unsigned int start, end; 26789cee8b1SHerbert Xu 26889cee8b1SHerbert Xu int rc; 26989cee8b1SHerbert Xu 27089cee8b1SHerbert Xu if (!peer || !max) 27189cee8b1SHerbert Xu return 0; 27289cee8b1SHerbert Xu 27389cee8b1SHerbert Xu start = qp->rid; 27489cee8b1SHerbert Xu end = atomic_inc_return(&peer->rid); 27589cee8b1SHerbert Xu qp->rid = end; 27689cee8b1SHerbert Xu 2775ab11c98SPavel Emelyanov rc = qp->q.fragments && (end - start) > max; 27889cee8b1SHerbert Xu 27989cee8b1SHerbert Xu if (rc) { 28089cee8b1SHerbert Xu IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 28189cee8b1SHerbert Xu } 28289cee8b1SHerbert Xu 28389cee8b1SHerbert Xu return rc; 28489cee8b1SHerbert Xu } 28589cee8b1SHerbert Xu 28689cee8b1SHerbert Xu static int ip_frag_reinit(struct ipq *qp) 28789cee8b1SHerbert Xu { 28889cee8b1SHerbert Xu struct sk_buff *fp; 28989cee8b1SHerbert Xu 29004128f23SPavel Emelyanov if (!mod_timer(&qp->q.timer, jiffies + ip4_frags_ctl.timeout)) { 2915ab11c98SPavel Emelyanov atomic_inc(&qp->q.refcnt); 29289cee8b1SHerbert Xu return -ETIMEDOUT; 29389cee8b1SHerbert Xu } 29489cee8b1SHerbert Xu 2955ab11c98SPavel Emelyanov fp = qp->q.fragments; 29689cee8b1SHerbert Xu do { 29789cee8b1SHerbert Xu struct sk_buff *xp = fp->next; 298*6ddc0822SPavel Emelyanov frag_kfree_skb(qp->q.net, fp, NULL); 29989cee8b1SHerbert Xu fp = xp; 30089cee8b1SHerbert Xu } while (fp); 30189cee8b1SHerbert Xu 3025ab11c98SPavel Emelyanov qp->q.last_in = 0; 3035ab11c98SPavel Emelyanov qp->q.len = 0; 3045ab11c98SPavel Emelyanov qp->q.meat = 0; 3055ab11c98SPavel Emelyanov qp->q.fragments = NULL; 30689cee8b1SHerbert Xu qp->iif = 0; 30789cee8b1SHerbert Xu 30889cee8b1SHerbert Xu return 0; 30989cee8b1SHerbert Xu } 31089cee8b1SHerbert Xu 3111da177e4SLinus Torvalds /* Add new segment to existing queue. */ 3121706d587SHerbert Xu static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) 3131da177e4SLinus Torvalds { 3141da177e4SLinus Torvalds struct sk_buff *prev, *next; 3151706d587SHerbert Xu struct net_device *dev; 3161da177e4SLinus Torvalds int flags, offset; 3171da177e4SLinus Torvalds int ihl, end; 3181706d587SHerbert Xu int err = -ENOENT; 3191da177e4SLinus Torvalds 3205ab11c98SPavel Emelyanov if (qp->q.last_in & COMPLETE) 3211da177e4SLinus Torvalds goto err; 3221da177e4SLinus Torvalds 32389cee8b1SHerbert Xu if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && 3241706d587SHerbert Xu unlikely(ip_frag_too_far(qp)) && 3251706d587SHerbert Xu unlikely(err = ip_frag_reinit(qp))) { 32689cee8b1SHerbert Xu ipq_kill(qp); 32789cee8b1SHerbert Xu goto err; 32889cee8b1SHerbert Xu } 32989cee8b1SHerbert Xu 330eddc9ec5SArnaldo Carvalho de Melo offset = ntohs(ip_hdr(skb)->frag_off); 3311da177e4SLinus Torvalds flags = offset & ~IP_OFFSET; 3321da177e4SLinus Torvalds offset &= IP_OFFSET; 3331da177e4SLinus Torvalds offset <<= 3; /* offset is in 8-byte chunks */ 334c9bdd4b5SArnaldo Carvalho de Melo ihl = ip_hdrlen(skb); 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds /* Determine the position of this fragment. */ 3371da177e4SLinus Torvalds end = offset + skb->len - ihl; 3381706d587SHerbert Xu err = -EINVAL; 3391da177e4SLinus Torvalds 3401da177e4SLinus Torvalds /* Is this the final fragment? */ 3411da177e4SLinus Torvalds if ((flags & IP_MF) == 0) { 3421da177e4SLinus Torvalds /* If we already have some bits beyond end 3431da177e4SLinus Torvalds * or have different end, the segment is corrrupted. 3441da177e4SLinus Torvalds */ 3455ab11c98SPavel Emelyanov if (end < qp->q.len || 3465ab11c98SPavel Emelyanov ((qp->q.last_in & LAST_IN) && end != qp->q.len)) 3471da177e4SLinus Torvalds goto err; 3485ab11c98SPavel Emelyanov qp->q.last_in |= LAST_IN; 3495ab11c98SPavel Emelyanov qp->q.len = end; 3501da177e4SLinus Torvalds } else { 3511da177e4SLinus Torvalds if (end&7) { 3521da177e4SLinus Torvalds end &= ~7; 3531da177e4SLinus Torvalds if (skb->ip_summed != CHECKSUM_UNNECESSARY) 3541da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_NONE; 3551da177e4SLinus Torvalds } 3565ab11c98SPavel Emelyanov if (end > qp->q.len) { 3571da177e4SLinus Torvalds /* Some bits beyond end -> corruption. */ 3585ab11c98SPavel Emelyanov if (qp->q.last_in & LAST_IN) 3591da177e4SLinus Torvalds goto err; 3605ab11c98SPavel Emelyanov qp->q.len = end; 3611da177e4SLinus Torvalds } 3621da177e4SLinus Torvalds } 3631da177e4SLinus Torvalds if (end == offset) 3641da177e4SLinus Torvalds goto err; 3651da177e4SLinus Torvalds 3661706d587SHerbert Xu err = -ENOMEM; 3671da177e4SLinus Torvalds if (pskb_pull(skb, ihl) == NULL) 3681da177e4SLinus Torvalds goto err; 3691706d587SHerbert Xu 3701706d587SHerbert Xu err = pskb_trim_rcsum(skb, end - offset); 3711706d587SHerbert Xu if (err) 3721da177e4SLinus Torvalds goto err; 3731da177e4SLinus Torvalds 3741da177e4SLinus Torvalds /* Find out which fragments are in front and at the back of us 3751da177e4SLinus Torvalds * in the chain of fragments so far. We must know where to put 3761da177e4SLinus Torvalds * this fragment, right? 3771da177e4SLinus Torvalds */ 3781da177e4SLinus Torvalds prev = NULL; 3795ab11c98SPavel Emelyanov for (next = qp->q.fragments; next != NULL; next = next->next) { 3801da177e4SLinus Torvalds if (FRAG_CB(next)->offset >= offset) 3811da177e4SLinus Torvalds break; /* bingo! */ 3821da177e4SLinus Torvalds prev = next; 3831da177e4SLinus Torvalds } 3841da177e4SLinus Torvalds 3851da177e4SLinus Torvalds /* We found where to put this one. Check for overlap with 3861da177e4SLinus Torvalds * preceding fragment, and, if needed, align things so that 3871da177e4SLinus Torvalds * any overlaps are eliminated. 3881da177e4SLinus Torvalds */ 3891da177e4SLinus Torvalds if (prev) { 3901da177e4SLinus Torvalds int i = (FRAG_CB(prev)->offset + prev->len) - offset; 3911da177e4SLinus Torvalds 3921da177e4SLinus Torvalds if (i > 0) { 3931da177e4SLinus Torvalds offset += i; 3941706d587SHerbert Xu err = -EINVAL; 3951da177e4SLinus Torvalds if (end <= offset) 3961da177e4SLinus Torvalds goto err; 3971706d587SHerbert Xu err = -ENOMEM; 3981da177e4SLinus Torvalds if (!pskb_pull(skb, i)) 3991da177e4SLinus Torvalds goto err; 4001da177e4SLinus Torvalds if (skb->ip_summed != CHECKSUM_UNNECESSARY) 4011da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_NONE; 4021da177e4SLinus Torvalds } 4031da177e4SLinus Torvalds } 4041da177e4SLinus Torvalds 4051706d587SHerbert Xu err = -ENOMEM; 4061706d587SHerbert Xu 4071da177e4SLinus Torvalds while (next && FRAG_CB(next)->offset < end) { 4081da177e4SLinus Torvalds int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ 4091da177e4SLinus Torvalds 4101da177e4SLinus Torvalds if (i < next->len) { 4111da177e4SLinus Torvalds /* Eat head of the next overlapped fragment 4121da177e4SLinus Torvalds * and leave the loop. The next ones cannot overlap. 4131da177e4SLinus Torvalds */ 4141da177e4SLinus Torvalds if (!pskb_pull(next, i)) 4151da177e4SLinus Torvalds goto err; 4161da177e4SLinus Torvalds FRAG_CB(next)->offset += i; 4175ab11c98SPavel Emelyanov qp->q.meat -= i; 4181da177e4SLinus Torvalds if (next->ip_summed != CHECKSUM_UNNECESSARY) 4191da177e4SLinus Torvalds next->ip_summed = CHECKSUM_NONE; 4201da177e4SLinus Torvalds break; 4211da177e4SLinus Torvalds } else { 4221da177e4SLinus Torvalds struct sk_buff *free_it = next; 4231da177e4SLinus Torvalds 42447c6bf77SPeter Zijlstra /* Old fragment is completely overridden with 4251da177e4SLinus Torvalds * new one drop it. 4261da177e4SLinus Torvalds */ 4271da177e4SLinus Torvalds next = next->next; 4281da177e4SLinus Torvalds 4291da177e4SLinus Torvalds if (prev) 4301da177e4SLinus Torvalds prev->next = next; 4311da177e4SLinus Torvalds else 4325ab11c98SPavel Emelyanov qp->q.fragments = next; 4331da177e4SLinus Torvalds 4345ab11c98SPavel Emelyanov qp->q.meat -= free_it->len; 435*6ddc0822SPavel Emelyanov frag_kfree_skb(qp->q.net, free_it, NULL); 4361da177e4SLinus Torvalds } 4371da177e4SLinus Torvalds } 4381da177e4SLinus Torvalds 4391da177e4SLinus Torvalds FRAG_CB(skb)->offset = offset; 4401da177e4SLinus Torvalds 4411da177e4SLinus Torvalds /* Insert this fragment in the chain of fragments. */ 4421da177e4SLinus Torvalds skb->next = next; 4431da177e4SLinus Torvalds if (prev) 4441da177e4SLinus Torvalds prev->next = skb; 4451da177e4SLinus Torvalds else 4465ab11c98SPavel Emelyanov qp->q.fragments = skb; 4471da177e4SLinus Torvalds 4481706d587SHerbert Xu dev = skb->dev; 4491706d587SHerbert Xu if (dev) { 4501706d587SHerbert Xu qp->iif = dev->ifindex; 4511da177e4SLinus Torvalds skb->dev = NULL; 4521706d587SHerbert Xu } 4535ab11c98SPavel Emelyanov qp->q.stamp = skb->tstamp; 4545ab11c98SPavel Emelyanov qp->q.meat += skb->len; 455*6ddc0822SPavel Emelyanov atomic_add(skb->truesize, &qp->q.net->mem); 4561da177e4SLinus Torvalds if (offset == 0) 4575ab11c98SPavel Emelyanov qp->q.last_in |= FIRST_IN; 4581da177e4SLinus Torvalds 4595ab11c98SPavel Emelyanov if (qp->q.last_in == (FIRST_IN | LAST_IN) && qp->q.meat == qp->q.len) 4601706d587SHerbert Xu return ip_frag_reasm(qp, prev, dev); 4611706d587SHerbert Xu 4627eb95156SPavel Emelyanov write_lock(&ip4_frags.lock); 4637eb95156SPavel Emelyanov list_move_tail(&qp->q.lru_list, &ip4_frags.lru_list); 4647eb95156SPavel Emelyanov write_unlock(&ip4_frags.lock); 4651706d587SHerbert Xu return -EINPROGRESS; 4661da177e4SLinus Torvalds 4671da177e4SLinus Torvalds err: 4681da177e4SLinus Torvalds kfree_skb(skb); 4691706d587SHerbert Xu return err; 4701da177e4SLinus Torvalds } 4711da177e4SLinus Torvalds 4721da177e4SLinus Torvalds 4731da177e4SLinus Torvalds /* Build a new IP datagram from all its fragments. */ 4741da177e4SLinus Torvalds 4751706d587SHerbert Xu static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, 4761706d587SHerbert Xu struct net_device *dev) 4771da177e4SLinus Torvalds { 4781da177e4SLinus Torvalds struct iphdr *iph; 4795ab11c98SPavel Emelyanov struct sk_buff *fp, *head = qp->q.fragments; 4801da177e4SLinus Torvalds int len; 4811da177e4SLinus Torvalds int ihlen; 4821706d587SHerbert Xu int err; 4831da177e4SLinus Torvalds 4841da177e4SLinus Torvalds ipq_kill(qp); 4851da177e4SLinus Torvalds 4861706d587SHerbert Xu /* Make the one we just received the head. */ 4871706d587SHerbert Xu if (prev) { 4881706d587SHerbert Xu head = prev->next; 4891706d587SHerbert Xu fp = skb_clone(head, GFP_ATOMIC); 4901706d587SHerbert Xu if (!fp) 4911706d587SHerbert Xu goto out_nomem; 4921706d587SHerbert Xu 4931706d587SHerbert Xu fp->next = head->next; 4941706d587SHerbert Xu prev->next = fp; 4951706d587SHerbert Xu 4965ab11c98SPavel Emelyanov skb_morph(head, qp->q.fragments); 4975ab11c98SPavel Emelyanov head->next = qp->q.fragments->next; 4981706d587SHerbert Xu 4995ab11c98SPavel Emelyanov kfree_skb(qp->q.fragments); 5005ab11c98SPavel Emelyanov qp->q.fragments = head; 5011706d587SHerbert Xu } 5021706d587SHerbert Xu 5031da177e4SLinus Torvalds BUG_TRAP(head != NULL); 5041da177e4SLinus Torvalds BUG_TRAP(FRAG_CB(head)->offset == 0); 5051da177e4SLinus Torvalds 5061da177e4SLinus Torvalds /* Allocate a new buffer for the datagram. */ 507c9bdd4b5SArnaldo Carvalho de Melo ihlen = ip_hdrlen(head); 5085ab11c98SPavel Emelyanov len = ihlen + qp->q.len; 5091da177e4SLinus Torvalds 5101706d587SHerbert Xu err = -E2BIG; 5111da177e4SLinus Torvalds if (len > 65535) 5121da177e4SLinus Torvalds goto out_oversize; 5131da177e4SLinus Torvalds 5141da177e4SLinus Torvalds /* Head of list must not be cloned. */ 5151da177e4SLinus Torvalds if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) 5161da177e4SLinus Torvalds goto out_nomem; 5171da177e4SLinus Torvalds 5181da177e4SLinus Torvalds /* If the first fragment is fragmented itself, we split 5191da177e4SLinus Torvalds * it to two chunks: the first with data and paged part 5201da177e4SLinus Torvalds * and the second, holding only fragments. */ 5211da177e4SLinus Torvalds if (skb_shinfo(head)->frag_list) { 5221da177e4SLinus Torvalds struct sk_buff *clone; 5231da177e4SLinus Torvalds int i, plen = 0; 5241da177e4SLinus Torvalds 5251da177e4SLinus Torvalds if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) 5261da177e4SLinus Torvalds goto out_nomem; 5271da177e4SLinus Torvalds clone->next = head->next; 5281da177e4SLinus Torvalds head->next = clone; 5291da177e4SLinus Torvalds skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; 5301da177e4SLinus Torvalds skb_shinfo(head)->frag_list = NULL; 5311da177e4SLinus Torvalds for (i=0; i<skb_shinfo(head)->nr_frags; i++) 5321da177e4SLinus Torvalds plen += skb_shinfo(head)->frags[i].size; 5331da177e4SLinus Torvalds clone->len = clone->data_len = head->data_len - plen; 5341da177e4SLinus Torvalds head->data_len -= clone->len; 5351da177e4SLinus Torvalds head->len -= clone->len; 5361da177e4SLinus Torvalds clone->csum = 0; 5371da177e4SLinus Torvalds clone->ip_summed = head->ip_summed; 538*6ddc0822SPavel Emelyanov atomic_add(clone->truesize, &qp->q.net->mem); 5391da177e4SLinus Torvalds } 5401da177e4SLinus Torvalds 5411da177e4SLinus Torvalds skb_shinfo(head)->frag_list = head->next; 542d56f90a7SArnaldo Carvalho de Melo skb_push(head, head->data - skb_network_header(head)); 543*6ddc0822SPavel Emelyanov atomic_sub(head->truesize, &qp->q.net->mem); 5441da177e4SLinus Torvalds 5451da177e4SLinus Torvalds for (fp=head->next; fp; fp = fp->next) { 5461da177e4SLinus Torvalds head->data_len += fp->len; 5471da177e4SLinus Torvalds head->len += fp->len; 5481da177e4SLinus Torvalds if (head->ip_summed != fp->ip_summed) 5491da177e4SLinus Torvalds head->ip_summed = CHECKSUM_NONE; 55084fa7933SPatrick McHardy else if (head->ip_summed == CHECKSUM_COMPLETE) 5511da177e4SLinus Torvalds head->csum = csum_add(head->csum, fp->csum); 5521da177e4SLinus Torvalds head->truesize += fp->truesize; 553*6ddc0822SPavel Emelyanov atomic_sub(fp->truesize, &qp->q.net->mem); 5541da177e4SLinus Torvalds } 5551da177e4SLinus Torvalds 5561da177e4SLinus Torvalds head->next = NULL; 5571da177e4SLinus Torvalds head->dev = dev; 5585ab11c98SPavel Emelyanov head->tstamp = qp->q.stamp; 5591da177e4SLinus Torvalds 560eddc9ec5SArnaldo Carvalho de Melo iph = ip_hdr(head); 5611da177e4SLinus Torvalds iph->frag_off = 0; 5621da177e4SLinus Torvalds iph->tot_len = htons(len); 5631da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMOKS); 5645ab11c98SPavel Emelyanov qp->q.fragments = NULL; 5651706d587SHerbert Xu return 0; 5661da177e4SLinus Torvalds 5671da177e4SLinus Torvalds out_nomem: 56864ce2073SPatrick McHardy LIMIT_NETDEBUG(KERN_ERR "IP: queue_glue: no memory for gluing " 56964ce2073SPatrick McHardy "queue %p\n", qp); 57045542479SDavid Howells err = -ENOMEM; 5711da177e4SLinus Torvalds goto out_fail; 5721da177e4SLinus Torvalds out_oversize: 5731da177e4SLinus Torvalds if (net_ratelimit()) 5741da177e4SLinus Torvalds printk(KERN_INFO 5751da177e4SLinus Torvalds "Oversized IP packet from %d.%d.%d.%d.\n", 5761da177e4SLinus Torvalds NIPQUAD(qp->saddr)); 5771da177e4SLinus Torvalds out_fail: 5781da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 5791706d587SHerbert Xu return err; 5801da177e4SLinus Torvalds } 5811da177e4SLinus Torvalds 5821da177e4SLinus Torvalds /* Process an incoming IP datagram fragment. */ 583776c729eSHerbert Xu int ip_defrag(struct sk_buff *skb, u32 user) 5841da177e4SLinus Torvalds { 5851da177e4SLinus Torvalds struct ipq *qp; 586ac18e750SPavel Emelyanov struct net *net; 5871da177e4SLinus Torvalds 5881da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMREQDS); 5891da177e4SLinus Torvalds 590ac18e750SPavel Emelyanov net = skb->dev->nd_net; 5911da177e4SLinus Torvalds /* Start by cleaning up the memory. */ 592*6ddc0822SPavel Emelyanov if (atomic_read(&net->ipv4.frags.mem) > ip4_frags_ctl.high_thresh) 593*6ddc0822SPavel Emelyanov ip_evictor(net); 5941da177e4SLinus Torvalds 5951da177e4SLinus Torvalds /* Lookup (or create) queue header */ 596ac18e750SPavel Emelyanov if ((qp = ip_find(net, ip_hdr(skb), user)) != NULL) { 5971706d587SHerbert Xu int ret; 5981da177e4SLinus Torvalds 5995ab11c98SPavel Emelyanov spin_lock(&qp->q.lock); 6001da177e4SLinus Torvalds 6011706d587SHerbert Xu ret = ip_frag_queue(qp, skb); 6021da177e4SLinus Torvalds 6035ab11c98SPavel Emelyanov spin_unlock(&qp->q.lock); 6044b6cb5d8SPavel Emelyanov ipq_put(qp); 605776c729eSHerbert Xu return ret; 6061da177e4SLinus Torvalds } 6071da177e4SLinus Torvalds 6081da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 6091da177e4SLinus Torvalds kfree_skb(skb); 610776c729eSHerbert Xu return -ENOMEM; 6111da177e4SLinus Torvalds } 6121da177e4SLinus Torvalds 6138d8354d2SPavel Emelyanov #ifdef CONFIG_SYSCTL 6148d8354d2SPavel Emelyanov static int zero; 6158d8354d2SPavel Emelyanov 6168d8354d2SPavel Emelyanov static struct ctl_table ip4_frags_ctl_table[] = { 6178d8354d2SPavel Emelyanov { 6188d8354d2SPavel Emelyanov .ctl_name = NET_IPV4_IPFRAG_HIGH_THRESH, 6198d8354d2SPavel Emelyanov .procname = "ipfrag_high_thresh", 6208d8354d2SPavel Emelyanov .data = &ip4_frags_ctl.high_thresh, 6218d8354d2SPavel Emelyanov .maxlen = sizeof(int), 6228d8354d2SPavel Emelyanov .mode = 0644, 6238d8354d2SPavel Emelyanov .proc_handler = &proc_dointvec 6248d8354d2SPavel Emelyanov }, 6258d8354d2SPavel Emelyanov { 6268d8354d2SPavel Emelyanov .ctl_name = NET_IPV4_IPFRAG_LOW_THRESH, 6278d8354d2SPavel Emelyanov .procname = "ipfrag_low_thresh", 6288d8354d2SPavel Emelyanov .data = &ip4_frags_ctl.low_thresh, 6298d8354d2SPavel Emelyanov .maxlen = sizeof(int), 6308d8354d2SPavel Emelyanov .mode = 0644, 6318d8354d2SPavel Emelyanov .proc_handler = &proc_dointvec 6328d8354d2SPavel Emelyanov }, 6338d8354d2SPavel Emelyanov { 6348d8354d2SPavel Emelyanov .ctl_name = NET_IPV4_IPFRAG_TIME, 6358d8354d2SPavel Emelyanov .procname = "ipfrag_time", 6368d8354d2SPavel Emelyanov .data = &ip4_frags_ctl.timeout, 6378d8354d2SPavel Emelyanov .maxlen = sizeof(int), 6388d8354d2SPavel Emelyanov .mode = 0644, 6398d8354d2SPavel Emelyanov .proc_handler = &proc_dointvec_jiffies, 6408d8354d2SPavel Emelyanov .strategy = &sysctl_jiffies 6418d8354d2SPavel Emelyanov }, 6428d8354d2SPavel Emelyanov { 6438d8354d2SPavel Emelyanov .ctl_name = NET_IPV4_IPFRAG_SECRET_INTERVAL, 6448d8354d2SPavel Emelyanov .procname = "ipfrag_secret_interval", 6458d8354d2SPavel Emelyanov .data = &ip4_frags_ctl.secret_interval, 6468d8354d2SPavel Emelyanov .maxlen = sizeof(int), 6478d8354d2SPavel Emelyanov .mode = 0644, 6488d8354d2SPavel Emelyanov .proc_handler = &proc_dointvec_jiffies, 6498d8354d2SPavel Emelyanov .strategy = &sysctl_jiffies 6508d8354d2SPavel Emelyanov }, 6518d8354d2SPavel Emelyanov { 6528d8354d2SPavel Emelyanov .procname = "ipfrag_max_dist", 6538d8354d2SPavel Emelyanov .data = &sysctl_ipfrag_max_dist, 6548d8354d2SPavel Emelyanov .maxlen = sizeof(int), 6558d8354d2SPavel Emelyanov .mode = 0644, 6568d8354d2SPavel Emelyanov .proc_handler = &proc_dointvec_minmax, 6578d8354d2SPavel Emelyanov .extra1 = &zero 6588d8354d2SPavel Emelyanov }, 6598d8354d2SPavel Emelyanov { } 6608d8354d2SPavel Emelyanov }; 6618d8354d2SPavel Emelyanov 6628d8354d2SPavel Emelyanov static int ip4_frags_ctl_register(struct net *net) 6638d8354d2SPavel Emelyanov { 6648d8354d2SPavel Emelyanov struct ctl_table_header *hdr; 6658d8354d2SPavel Emelyanov 6668d8354d2SPavel Emelyanov hdr = register_net_sysctl_table(net, net_ipv4_ctl_path, 6678d8354d2SPavel Emelyanov ip4_frags_ctl_table); 6688d8354d2SPavel Emelyanov return hdr == NULL ? -ENOMEM : 0; 6698d8354d2SPavel Emelyanov } 6708d8354d2SPavel Emelyanov #else 6718d8354d2SPavel Emelyanov static inline int ip4_frags_ctl_register(struct net *net) 6728d8354d2SPavel Emelyanov { 6738d8354d2SPavel Emelyanov return 0; 6748d8354d2SPavel Emelyanov } 6758d8354d2SPavel Emelyanov #endif 6768d8354d2SPavel Emelyanov 6778d8354d2SPavel Emelyanov static int ipv4_frags_init_net(struct net *net) 6788d8354d2SPavel Emelyanov { 679e5a2bb84SPavel Emelyanov inet_frags_init_net(&net->ipv4.frags); 680e5a2bb84SPavel Emelyanov 6818d8354d2SPavel Emelyanov return ip4_frags_ctl_register(net); 6828d8354d2SPavel Emelyanov } 6838d8354d2SPavel Emelyanov 684b7aa0bf7SEric Dumazet void __init ipfrag_init(void) 6851da177e4SLinus Torvalds { 6868d8354d2SPavel Emelyanov ipv4_frags_init_net(&init_net); 68704128f23SPavel Emelyanov ip4_frags.ctl = &ip4_frags_ctl; 688321a3a99SPavel Emelyanov ip4_frags.hashfn = ip4_hashfn; 689c6fda282SPavel Emelyanov ip4_frags.constructor = ip4_frag_init; 6901e4b8287SPavel Emelyanov ip4_frags.destructor = ip4_frag_free; 6911e4b8287SPavel Emelyanov ip4_frags.skb_free = NULL; 6921e4b8287SPavel Emelyanov ip4_frags.qsize = sizeof(struct ipq); 693abd6523dSPavel Emelyanov ip4_frags.match = ip4_frag_match; 694e521db9dSPavel Emelyanov ip4_frags.frag_expire = ip_expire; 6957eb95156SPavel Emelyanov inet_frags_init(&ip4_frags); 6961da177e4SLinus Torvalds } 6971da177e4SLinus Torvalds 6981da177e4SLinus Torvalds EXPORT_SYMBOL(ip_defrag); 699