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 53ab32ea5dSBrian Haley 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 7704128f23SPavel Emelyanov 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 987eb95156SPavel Emelyanov int ip_frag_nqueues(void) 997eb95156SPavel Emelyanov { 1007eb95156SPavel Emelyanov return ip4_frags.nqueues; 1017eb95156SPavel Emelyanov } 1021da177e4SLinus Torvalds 1037eb95156SPavel Emelyanov int ip_frag_mem(void) 1047eb95156SPavel Emelyanov { 1057eb95156SPavel Emelyanov return atomic_read(&ip4_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 11118277770SAl Viro static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot) 1121da177e4SLinus Torvalds { 11318277770SAl Viro return jhash_3words((__force u32)id << 16 | prot, 11418277770SAl Viro (__force u32)saddr, (__force u32)daddr, 1157eb95156SPavel Emelyanov ip4_frags.rnd) & (INETFRAGS_HASHSZ - 1); 1161da177e4SLinus Torvalds } 1171da177e4SLinus Torvalds 118321a3a99SPavel Emelyanov static unsigned int ip4_hashfn(struct inet_frag_queue *q) 1191da177e4SLinus Torvalds { 120321a3a99SPavel Emelyanov struct ipq *ipq; 1211da177e4SLinus Torvalds 122321a3a99SPavel Emelyanov ipq = container_of(q, struct ipq, q); 123321a3a99SPavel Emelyanov return ipqhashfn(ipq->id, ipq->saddr, ipq->daddr, ipq->protocol); 1241da177e4SLinus Torvalds } 1251da177e4SLinus Torvalds 1261da177e4SLinus Torvalds /* Memory Tracking Functions. */ 1271da177e4SLinus Torvalds static __inline__ void frag_kfree_skb(struct sk_buff *skb, int *work) 1281da177e4SLinus Torvalds { 1291da177e4SLinus Torvalds if (work) 1301da177e4SLinus Torvalds *work -= skb->truesize; 1317eb95156SPavel Emelyanov atomic_sub(skb->truesize, &ip4_frags.mem); 1321da177e4SLinus Torvalds kfree_skb(skb); 1331da177e4SLinus Torvalds } 1341da177e4SLinus Torvalds 1351e4b8287SPavel Emelyanov static __inline__ void ip4_frag_free(struct inet_frag_queue *q) 1361da177e4SLinus Torvalds { 1371e4b8287SPavel Emelyanov struct ipq *qp; 1381e4b8287SPavel Emelyanov 1391e4b8287SPavel Emelyanov qp = container_of(q, struct ipq, q); 1401e4b8287SPavel Emelyanov if (qp->peer) 1411e4b8287SPavel Emelyanov inet_putpeer(qp->peer); 1421da177e4SLinus Torvalds kfree(qp); 1431da177e4SLinus Torvalds } 1441da177e4SLinus Torvalds 1451da177e4SLinus Torvalds static __inline__ struct ipq *frag_alloc_queue(void) 1461da177e4SLinus Torvalds { 1471da177e4SLinus Torvalds struct ipq *qp = kmalloc(sizeof(struct ipq), GFP_ATOMIC); 1481da177e4SLinus Torvalds 1491da177e4SLinus Torvalds if (!qp) 1501da177e4SLinus Torvalds return NULL; 1517eb95156SPavel Emelyanov atomic_add(sizeof(struct ipq), &ip4_frags.mem); 1521da177e4SLinus Torvalds return qp; 1531da177e4SLinus Torvalds } 1541da177e4SLinus Torvalds 1551da177e4SLinus Torvalds 1561da177e4SLinus Torvalds /* Destruction primitives. */ 1571da177e4SLinus Torvalds 1584b6cb5d8SPavel Emelyanov static __inline__ void ipq_put(struct ipq *ipq) 1591da177e4SLinus Torvalds { 160762cc408SPavel Emelyanov inet_frag_put(&ipq->q, &ip4_frags); 1611da177e4SLinus Torvalds } 1621da177e4SLinus Torvalds 1631da177e4SLinus Torvalds /* Kill ipq entry. It is not destroyed immediately, 1641da177e4SLinus Torvalds * because caller (and someone more) holds reference count. 1651da177e4SLinus Torvalds */ 1661da177e4SLinus Torvalds static void ipq_kill(struct ipq *ipq) 1671da177e4SLinus Torvalds { 168277e650dSPavel Emelyanov inet_frag_kill(&ipq->q, &ip4_frags); 1691da177e4SLinus Torvalds } 1701da177e4SLinus Torvalds 1711da177e4SLinus Torvalds /* Memory limiting on fragments. Evictor trashes the oldest 1721da177e4SLinus Torvalds * fragment queue until we are back under the threshold. 1731da177e4SLinus Torvalds */ 1741da177e4SLinus Torvalds static void ip_evictor(void) 1751da177e4SLinus Torvalds { 1768e7999c4SPavel Emelyanov int evicted; 1771da177e4SLinus Torvalds 1788e7999c4SPavel Emelyanov evicted = inet_frag_evictor(&ip4_frags); 1798e7999c4SPavel Emelyanov if (evicted) 1808e7999c4SPavel Emelyanov IP_ADD_STATS_BH(IPSTATS_MIB_REASMFAILS, evicted); 1811da177e4SLinus Torvalds } 1821da177e4SLinus Torvalds 1831da177e4SLinus Torvalds /* 1841da177e4SLinus Torvalds * Oops, a fragment queue timed out. Kill it and send an ICMP reply. 1851da177e4SLinus Torvalds */ 1861da177e4SLinus Torvalds static void ip_expire(unsigned long arg) 1871da177e4SLinus Torvalds { 1881da177e4SLinus Torvalds struct ipq *qp = (struct ipq *) arg; 1891da177e4SLinus Torvalds 1905ab11c98SPavel Emelyanov spin_lock(&qp->q.lock); 1911da177e4SLinus Torvalds 1925ab11c98SPavel Emelyanov if (qp->q.last_in & COMPLETE) 1931da177e4SLinus Torvalds goto out; 1941da177e4SLinus Torvalds 1951da177e4SLinus Torvalds ipq_kill(qp); 1961da177e4SLinus Torvalds 1971da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMTIMEOUT); 1981da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 1991da177e4SLinus Torvalds 2005ab11c98SPavel Emelyanov if ((qp->q.last_in&FIRST_IN) && qp->q.fragments != NULL) { 2015ab11c98SPavel Emelyanov struct sk_buff *head = qp->q.fragments; 2021da177e4SLinus Torvalds /* Send an ICMP "Fragment Reassembly Timeout" message. */ 203881d966bSEric W. Biederman if ((head->dev = dev_get_by_index(&init_net, qp->iif)) != NULL) { 2041da177e4SLinus Torvalds icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0); 2051da177e4SLinus Torvalds dev_put(head->dev); 2061da177e4SLinus Torvalds } 2071da177e4SLinus Torvalds } 2081da177e4SLinus Torvalds out: 2095ab11c98SPavel Emelyanov spin_unlock(&qp->q.lock); 2104b6cb5d8SPavel Emelyanov ipq_put(qp); 2111da177e4SLinus Torvalds } 2121da177e4SLinus Torvalds 2131da177e4SLinus Torvalds /* Creation primitives. */ 2141da177e4SLinus Torvalds 21555c0022eSDavid S. Miller static struct ipq *ip_frag_intern(struct ipq *qp_in) 2161da177e4SLinus Torvalds { 2171da177e4SLinus Torvalds struct ipq *qp; 218e7c8a41eSYasuyuki Kozakai #ifdef CONFIG_SMP 219e7c8a41eSYasuyuki Kozakai struct hlist_node *n; 220e7c8a41eSYasuyuki Kozakai #endif 22155c0022eSDavid S. Miller unsigned int hash; 22255c0022eSDavid S. Miller 2237eb95156SPavel Emelyanov write_lock(&ip4_frags.lock); 22455c0022eSDavid S. Miller hash = ipqhashfn(qp_in->id, qp_in->saddr, qp_in->daddr, 22555c0022eSDavid S. Miller qp_in->protocol); 2261da177e4SLinus Torvalds #ifdef CONFIG_SMP 2271da177e4SLinus Torvalds /* With SMP race we have to recheck hash table, because 2281da177e4SLinus Torvalds * such entry could be created on other cpu, while we 2291da177e4SLinus Torvalds * promoted read lock to write lock. 2301da177e4SLinus Torvalds */ 2317eb95156SPavel Emelyanov hlist_for_each_entry(qp, n, &ip4_frags.hash[hash], q.list) { 2321da177e4SLinus Torvalds if (qp->id == qp_in->id && 2331da177e4SLinus Torvalds qp->saddr == qp_in->saddr && 2341da177e4SLinus Torvalds qp->daddr == qp_in->daddr && 2351da177e4SLinus Torvalds qp->protocol == qp_in->protocol && 2361da177e4SLinus Torvalds qp->user == qp_in->user) { 2375ab11c98SPavel Emelyanov atomic_inc(&qp->q.refcnt); 2387eb95156SPavel Emelyanov write_unlock(&ip4_frags.lock); 2395ab11c98SPavel Emelyanov qp_in->q.last_in |= COMPLETE; 2404b6cb5d8SPavel Emelyanov ipq_put(qp_in); 2411da177e4SLinus Torvalds return qp; 2421da177e4SLinus Torvalds } 2431da177e4SLinus Torvalds } 2441da177e4SLinus Torvalds #endif 2451da177e4SLinus Torvalds qp = qp_in; 2461da177e4SLinus Torvalds 24704128f23SPavel Emelyanov if (!mod_timer(&qp->q.timer, jiffies + ip4_frags_ctl.timeout)) 2485ab11c98SPavel Emelyanov atomic_inc(&qp->q.refcnt); 2491da177e4SLinus Torvalds 2505ab11c98SPavel Emelyanov atomic_inc(&qp->q.refcnt); 2517eb95156SPavel Emelyanov hlist_add_head(&qp->q.list, &ip4_frags.hash[hash]); 2525ab11c98SPavel Emelyanov INIT_LIST_HEAD(&qp->q.lru_list); 2537eb95156SPavel Emelyanov list_add_tail(&qp->q.lru_list, &ip4_frags.lru_list); 2547eb95156SPavel Emelyanov ip4_frags.nqueues++; 2557eb95156SPavel Emelyanov write_unlock(&ip4_frags.lock); 2561da177e4SLinus Torvalds return qp; 2571da177e4SLinus Torvalds } 2581da177e4SLinus Torvalds 2591da177e4SLinus Torvalds /* Add an entry to the 'ipq' queue for a newly received IP datagram. */ 26055c0022eSDavid S. Miller static struct ipq *ip_frag_create(struct iphdr *iph, u32 user) 2611da177e4SLinus Torvalds { 2621da177e4SLinus Torvalds struct ipq *qp; 2631da177e4SLinus Torvalds 2641da177e4SLinus Torvalds if ((qp = frag_alloc_queue()) == NULL) 2651da177e4SLinus Torvalds goto out_nomem; 2661da177e4SLinus Torvalds 2671da177e4SLinus Torvalds qp->protocol = iph->protocol; 2685ab11c98SPavel Emelyanov qp->q.last_in = 0; 2691da177e4SLinus Torvalds qp->id = iph->id; 2701da177e4SLinus Torvalds qp->saddr = iph->saddr; 2711da177e4SLinus Torvalds qp->daddr = iph->daddr; 2721da177e4SLinus Torvalds qp->user = user; 2735ab11c98SPavel Emelyanov qp->q.len = 0; 2745ab11c98SPavel Emelyanov qp->q.meat = 0; 2755ab11c98SPavel Emelyanov qp->q.fragments = NULL; 2761da177e4SLinus Torvalds qp->iif = 0; 27789cee8b1SHerbert Xu qp->peer = sysctl_ipfrag_max_dist ? inet_getpeer(iph->saddr, 1) : NULL; 2781da177e4SLinus Torvalds 2791da177e4SLinus Torvalds /* Initialize a timer for this entry. */ 2805ab11c98SPavel Emelyanov init_timer(&qp->q.timer); 2815ab11c98SPavel Emelyanov qp->q.timer.data = (unsigned long) qp; /* pointer to queue */ 2825ab11c98SPavel Emelyanov qp->q.timer.function = ip_expire; /* expire function */ 2835ab11c98SPavel Emelyanov spin_lock_init(&qp->q.lock); 2845ab11c98SPavel Emelyanov atomic_set(&qp->q.refcnt, 1); 2851da177e4SLinus Torvalds 28655c0022eSDavid S. Miller return ip_frag_intern(qp); 2871da177e4SLinus Torvalds 2881da177e4SLinus Torvalds out_nomem: 28964ce2073SPatrick McHardy LIMIT_NETDEBUG(KERN_ERR "ip_frag_create: no memory left !\n"); 2901da177e4SLinus Torvalds return NULL; 2911da177e4SLinus Torvalds } 2921da177e4SLinus Torvalds 2931da177e4SLinus Torvalds /* Find the correct entry in the "incomplete datagrams" queue for 2941da177e4SLinus Torvalds * this IP datagram, and create new one, if nothing is found. 2951da177e4SLinus Torvalds */ 2961da177e4SLinus Torvalds static inline struct ipq *ip_find(struct iphdr *iph, u32 user) 2971da177e4SLinus Torvalds { 29876ab608dSAlexey Dobriyan __be16 id = iph->id; 29918277770SAl Viro __be32 saddr = iph->saddr; 30018277770SAl Viro __be32 daddr = iph->daddr; 3011da177e4SLinus Torvalds __u8 protocol = iph->protocol; 30255c0022eSDavid S. Miller unsigned int hash; 3031da177e4SLinus Torvalds struct ipq *qp; 304e7c8a41eSYasuyuki Kozakai struct hlist_node *n; 3051da177e4SLinus Torvalds 3067eb95156SPavel Emelyanov read_lock(&ip4_frags.lock); 30755c0022eSDavid S. Miller hash = ipqhashfn(id, saddr, daddr, protocol); 3087eb95156SPavel Emelyanov hlist_for_each_entry(qp, n, &ip4_frags.hash[hash], q.list) { 3091da177e4SLinus Torvalds if (qp->id == id && 3101da177e4SLinus Torvalds qp->saddr == saddr && 3111da177e4SLinus Torvalds qp->daddr == daddr && 3121da177e4SLinus Torvalds qp->protocol == protocol && 3131da177e4SLinus Torvalds qp->user == user) { 3145ab11c98SPavel Emelyanov atomic_inc(&qp->q.refcnt); 3157eb95156SPavel Emelyanov read_unlock(&ip4_frags.lock); 3161da177e4SLinus Torvalds return qp; 3171da177e4SLinus Torvalds } 3181da177e4SLinus Torvalds } 3197eb95156SPavel Emelyanov read_unlock(&ip4_frags.lock); 3201da177e4SLinus Torvalds 32155c0022eSDavid S. Miller return ip_frag_create(iph, user); 3221da177e4SLinus Torvalds } 3231da177e4SLinus Torvalds 32489cee8b1SHerbert Xu /* Is the fragment too far ahead to be part of ipq? */ 32589cee8b1SHerbert Xu static inline int ip_frag_too_far(struct ipq *qp) 32689cee8b1SHerbert Xu { 32789cee8b1SHerbert Xu struct inet_peer *peer = qp->peer; 32889cee8b1SHerbert Xu unsigned int max = sysctl_ipfrag_max_dist; 32989cee8b1SHerbert Xu unsigned int start, end; 33089cee8b1SHerbert Xu 33189cee8b1SHerbert Xu int rc; 33289cee8b1SHerbert Xu 33389cee8b1SHerbert Xu if (!peer || !max) 33489cee8b1SHerbert Xu return 0; 33589cee8b1SHerbert Xu 33689cee8b1SHerbert Xu start = qp->rid; 33789cee8b1SHerbert Xu end = atomic_inc_return(&peer->rid); 33889cee8b1SHerbert Xu qp->rid = end; 33989cee8b1SHerbert Xu 3405ab11c98SPavel Emelyanov rc = qp->q.fragments && (end - start) > max; 34189cee8b1SHerbert Xu 34289cee8b1SHerbert Xu if (rc) { 34389cee8b1SHerbert Xu IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 34489cee8b1SHerbert Xu } 34589cee8b1SHerbert Xu 34689cee8b1SHerbert Xu return rc; 34789cee8b1SHerbert Xu } 34889cee8b1SHerbert Xu 34989cee8b1SHerbert Xu static int ip_frag_reinit(struct ipq *qp) 35089cee8b1SHerbert Xu { 35189cee8b1SHerbert Xu struct sk_buff *fp; 35289cee8b1SHerbert Xu 35304128f23SPavel Emelyanov if (!mod_timer(&qp->q.timer, jiffies + ip4_frags_ctl.timeout)) { 3545ab11c98SPavel Emelyanov atomic_inc(&qp->q.refcnt); 35589cee8b1SHerbert Xu return -ETIMEDOUT; 35689cee8b1SHerbert Xu } 35789cee8b1SHerbert Xu 3585ab11c98SPavel Emelyanov fp = qp->q.fragments; 35989cee8b1SHerbert Xu do { 36089cee8b1SHerbert Xu struct sk_buff *xp = fp->next; 36189cee8b1SHerbert Xu frag_kfree_skb(fp, NULL); 36289cee8b1SHerbert Xu fp = xp; 36389cee8b1SHerbert Xu } while (fp); 36489cee8b1SHerbert Xu 3655ab11c98SPavel Emelyanov qp->q.last_in = 0; 3665ab11c98SPavel Emelyanov qp->q.len = 0; 3675ab11c98SPavel Emelyanov qp->q.meat = 0; 3685ab11c98SPavel Emelyanov qp->q.fragments = NULL; 36989cee8b1SHerbert Xu qp->iif = 0; 37089cee8b1SHerbert Xu 37189cee8b1SHerbert Xu return 0; 37289cee8b1SHerbert Xu } 37389cee8b1SHerbert Xu 3741da177e4SLinus Torvalds /* Add new segment to existing queue. */ 3751706d587SHerbert Xu static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) 3761da177e4SLinus Torvalds { 3771da177e4SLinus Torvalds struct sk_buff *prev, *next; 3781706d587SHerbert Xu struct net_device *dev; 3791da177e4SLinus Torvalds int flags, offset; 3801da177e4SLinus Torvalds int ihl, end; 3811706d587SHerbert Xu int err = -ENOENT; 3821da177e4SLinus Torvalds 3835ab11c98SPavel Emelyanov if (qp->q.last_in & COMPLETE) 3841da177e4SLinus Torvalds goto err; 3851da177e4SLinus Torvalds 38689cee8b1SHerbert Xu if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && 3871706d587SHerbert Xu unlikely(ip_frag_too_far(qp)) && 3881706d587SHerbert Xu unlikely(err = ip_frag_reinit(qp))) { 38989cee8b1SHerbert Xu ipq_kill(qp); 39089cee8b1SHerbert Xu goto err; 39189cee8b1SHerbert Xu } 39289cee8b1SHerbert Xu 393eddc9ec5SArnaldo Carvalho de Melo offset = ntohs(ip_hdr(skb)->frag_off); 3941da177e4SLinus Torvalds flags = offset & ~IP_OFFSET; 3951da177e4SLinus Torvalds offset &= IP_OFFSET; 3961da177e4SLinus Torvalds offset <<= 3; /* offset is in 8-byte chunks */ 397c9bdd4b5SArnaldo Carvalho de Melo ihl = ip_hdrlen(skb); 3981da177e4SLinus Torvalds 3991da177e4SLinus Torvalds /* Determine the position of this fragment. */ 4001da177e4SLinus Torvalds end = offset + skb->len - ihl; 4011706d587SHerbert Xu err = -EINVAL; 4021da177e4SLinus Torvalds 4031da177e4SLinus Torvalds /* Is this the final fragment? */ 4041da177e4SLinus Torvalds if ((flags & IP_MF) == 0) { 4051da177e4SLinus Torvalds /* If we already have some bits beyond end 4061da177e4SLinus Torvalds * or have different end, the segment is corrrupted. 4071da177e4SLinus Torvalds */ 4085ab11c98SPavel Emelyanov if (end < qp->q.len || 4095ab11c98SPavel Emelyanov ((qp->q.last_in & LAST_IN) && end != qp->q.len)) 4101da177e4SLinus Torvalds goto err; 4115ab11c98SPavel Emelyanov qp->q.last_in |= LAST_IN; 4125ab11c98SPavel Emelyanov qp->q.len = end; 4131da177e4SLinus Torvalds } else { 4141da177e4SLinus Torvalds if (end&7) { 4151da177e4SLinus Torvalds end &= ~7; 4161da177e4SLinus Torvalds if (skb->ip_summed != CHECKSUM_UNNECESSARY) 4171da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_NONE; 4181da177e4SLinus Torvalds } 4195ab11c98SPavel Emelyanov if (end > qp->q.len) { 4201da177e4SLinus Torvalds /* Some bits beyond end -> corruption. */ 4215ab11c98SPavel Emelyanov if (qp->q.last_in & LAST_IN) 4221da177e4SLinus Torvalds goto err; 4235ab11c98SPavel Emelyanov qp->q.len = end; 4241da177e4SLinus Torvalds } 4251da177e4SLinus Torvalds } 4261da177e4SLinus Torvalds if (end == offset) 4271da177e4SLinus Torvalds goto err; 4281da177e4SLinus Torvalds 4291706d587SHerbert Xu err = -ENOMEM; 4301da177e4SLinus Torvalds if (pskb_pull(skb, ihl) == NULL) 4311da177e4SLinus Torvalds goto err; 4321706d587SHerbert Xu 4331706d587SHerbert Xu err = pskb_trim_rcsum(skb, end - offset); 4341706d587SHerbert Xu if (err) 4351da177e4SLinus Torvalds goto err; 4361da177e4SLinus Torvalds 4371da177e4SLinus Torvalds /* Find out which fragments are in front and at the back of us 4381da177e4SLinus Torvalds * in the chain of fragments so far. We must know where to put 4391da177e4SLinus Torvalds * this fragment, right? 4401da177e4SLinus Torvalds */ 4411da177e4SLinus Torvalds prev = NULL; 4425ab11c98SPavel Emelyanov for (next = qp->q.fragments; next != NULL; next = next->next) { 4431da177e4SLinus Torvalds if (FRAG_CB(next)->offset >= offset) 4441da177e4SLinus Torvalds break; /* bingo! */ 4451da177e4SLinus Torvalds prev = next; 4461da177e4SLinus Torvalds } 4471da177e4SLinus Torvalds 4481da177e4SLinus Torvalds /* We found where to put this one. Check for overlap with 4491da177e4SLinus Torvalds * preceding fragment, and, if needed, align things so that 4501da177e4SLinus Torvalds * any overlaps are eliminated. 4511da177e4SLinus Torvalds */ 4521da177e4SLinus Torvalds if (prev) { 4531da177e4SLinus Torvalds int i = (FRAG_CB(prev)->offset + prev->len) - offset; 4541da177e4SLinus Torvalds 4551da177e4SLinus Torvalds if (i > 0) { 4561da177e4SLinus Torvalds offset += i; 4571706d587SHerbert Xu err = -EINVAL; 4581da177e4SLinus Torvalds if (end <= offset) 4591da177e4SLinus Torvalds goto err; 4601706d587SHerbert Xu err = -ENOMEM; 4611da177e4SLinus Torvalds if (!pskb_pull(skb, i)) 4621da177e4SLinus Torvalds goto err; 4631da177e4SLinus Torvalds if (skb->ip_summed != CHECKSUM_UNNECESSARY) 4641da177e4SLinus Torvalds skb->ip_summed = CHECKSUM_NONE; 4651da177e4SLinus Torvalds } 4661da177e4SLinus Torvalds } 4671da177e4SLinus Torvalds 4681706d587SHerbert Xu err = -ENOMEM; 4691706d587SHerbert Xu 4701da177e4SLinus Torvalds while (next && FRAG_CB(next)->offset < end) { 4711da177e4SLinus Torvalds int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ 4721da177e4SLinus Torvalds 4731da177e4SLinus Torvalds if (i < next->len) { 4741da177e4SLinus Torvalds /* Eat head of the next overlapped fragment 4751da177e4SLinus Torvalds * and leave the loop. The next ones cannot overlap. 4761da177e4SLinus Torvalds */ 4771da177e4SLinus Torvalds if (!pskb_pull(next, i)) 4781da177e4SLinus Torvalds goto err; 4791da177e4SLinus Torvalds FRAG_CB(next)->offset += i; 4805ab11c98SPavel Emelyanov qp->q.meat -= i; 4811da177e4SLinus Torvalds if (next->ip_summed != CHECKSUM_UNNECESSARY) 4821da177e4SLinus Torvalds next->ip_summed = CHECKSUM_NONE; 4831da177e4SLinus Torvalds break; 4841da177e4SLinus Torvalds } else { 4851da177e4SLinus Torvalds struct sk_buff *free_it = next; 4861da177e4SLinus Torvalds 48747c6bf77SPeter Zijlstra /* Old fragment is completely overridden with 4881da177e4SLinus Torvalds * new one drop it. 4891da177e4SLinus Torvalds */ 4901da177e4SLinus Torvalds next = next->next; 4911da177e4SLinus Torvalds 4921da177e4SLinus Torvalds if (prev) 4931da177e4SLinus Torvalds prev->next = next; 4941da177e4SLinus Torvalds else 4955ab11c98SPavel Emelyanov qp->q.fragments = next; 4961da177e4SLinus Torvalds 4975ab11c98SPavel Emelyanov qp->q.meat -= free_it->len; 4981da177e4SLinus Torvalds frag_kfree_skb(free_it, NULL); 4991da177e4SLinus Torvalds } 5001da177e4SLinus Torvalds } 5011da177e4SLinus Torvalds 5021da177e4SLinus Torvalds FRAG_CB(skb)->offset = offset; 5031da177e4SLinus Torvalds 5041da177e4SLinus Torvalds /* Insert this fragment in the chain of fragments. */ 5051da177e4SLinus Torvalds skb->next = next; 5061da177e4SLinus Torvalds if (prev) 5071da177e4SLinus Torvalds prev->next = skb; 5081da177e4SLinus Torvalds else 5095ab11c98SPavel Emelyanov qp->q.fragments = skb; 5101da177e4SLinus Torvalds 5111706d587SHerbert Xu dev = skb->dev; 5121706d587SHerbert Xu if (dev) { 5131706d587SHerbert Xu qp->iif = dev->ifindex; 5141da177e4SLinus Torvalds skb->dev = NULL; 5151706d587SHerbert Xu } 5165ab11c98SPavel Emelyanov qp->q.stamp = skb->tstamp; 5175ab11c98SPavel Emelyanov qp->q.meat += skb->len; 5187eb95156SPavel Emelyanov atomic_add(skb->truesize, &ip4_frags.mem); 5191da177e4SLinus Torvalds if (offset == 0) 5205ab11c98SPavel Emelyanov qp->q.last_in |= FIRST_IN; 5211da177e4SLinus Torvalds 5225ab11c98SPavel Emelyanov if (qp->q.last_in == (FIRST_IN | LAST_IN) && qp->q.meat == qp->q.len) 5231706d587SHerbert Xu return ip_frag_reasm(qp, prev, dev); 5241706d587SHerbert Xu 5257eb95156SPavel Emelyanov write_lock(&ip4_frags.lock); 5267eb95156SPavel Emelyanov list_move_tail(&qp->q.lru_list, &ip4_frags.lru_list); 5277eb95156SPavel Emelyanov write_unlock(&ip4_frags.lock); 5281706d587SHerbert Xu return -EINPROGRESS; 5291da177e4SLinus Torvalds 5301da177e4SLinus Torvalds err: 5311da177e4SLinus Torvalds kfree_skb(skb); 5321706d587SHerbert Xu return err; 5331da177e4SLinus Torvalds } 5341da177e4SLinus Torvalds 5351da177e4SLinus Torvalds 5361da177e4SLinus Torvalds /* Build a new IP datagram from all its fragments. */ 5371da177e4SLinus Torvalds 5381706d587SHerbert Xu static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, 5391706d587SHerbert Xu struct net_device *dev) 5401da177e4SLinus Torvalds { 5411da177e4SLinus Torvalds struct iphdr *iph; 5425ab11c98SPavel Emelyanov struct sk_buff *fp, *head = qp->q.fragments; 5431da177e4SLinus Torvalds int len; 5441da177e4SLinus Torvalds int ihlen; 5451706d587SHerbert Xu int err; 5461da177e4SLinus Torvalds 5471da177e4SLinus Torvalds ipq_kill(qp); 5481da177e4SLinus Torvalds 5491706d587SHerbert Xu /* Make the one we just received the head. */ 5501706d587SHerbert Xu if (prev) { 5511706d587SHerbert Xu head = prev->next; 5521706d587SHerbert Xu fp = skb_clone(head, GFP_ATOMIC); 5531706d587SHerbert Xu 5541706d587SHerbert Xu if (!fp) 5551706d587SHerbert Xu goto out_nomem; 5561706d587SHerbert Xu 5571706d587SHerbert Xu fp->next = head->next; 5581706d587SHerbert Xu prev->next = fp; 5591706d587SHerbert Xu 5605ab11c98SPavel Emelyanov skb_morph(head, qp->q.fragments); 5615ab11c98SPavel Emelyanov head->next = qp->q.fragments->next; 5621706d587SHerbert Xu 5635ab11c98SPavel Emelyanov kfree_skb(qp->q.fragments); 5645ab11c98SPavel Emelyanov qp->q.fragments = head; 5651706d587SHerbert Xu } 5661706d587SHerbert Xu 5671da177e4SLinus Torvalds BUG_TRAP(head != NULL); 5681da177e4SLinus Torvalds BUG_TRAP(FRAG_CB(head)->offset == 0); 5691da177e4SLinus Torvalds 5701da177e4SLinus Torvalds /* Allocate a new buffer for the datagram. */ 571c9bdd4b5SArnaldo Carvalho de Melo ihlen = ip_hdrlen(head); 5725ab11c98SPavel Emelyanov len = ihlen + qp->q.len; 5731da177e4SLinus Torvalds 5741706d587SHerbert Xu err = -E2BIG; 5751da177e4SLinus Torvalds if (len > 65535) 5761da177e4SLinus Torvalds goto out_oversize; 5771da177e4SLinus Torvalds 5781da177e4SLinus Torvalds /* Head of list must not be cloned. */ 5791706d587SHerbert Xu err = -ENOMEM; 5801da177e4SLinus Torvalds if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) 5811da177e4SLinus Torvalds goto out_nomem; 5821da177e4SLinus Torvalds 5831da177e4SLinus Torvalds /* If the first fragment is fragmented itself, we split 5841da177e4SLinus Torvalds * it to two chunks: the first with data and paged part 5851da177e4SLinus Torvalds * and the second, holding only fragments. */ 5861da177e4SLinus Torvalds if (skb_shinfo(head)->frag_list) { 5871da177e4SLinus Torvalds struct sk_buff *clone; 5881da177e4SLinus Torvalds int i, plen = 0; 5891da177e4SLinus Torvalds 5901da177e4SLinus Torvalds if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) 5911da177e4SLinus Torvalds goto out_nomem; 5921da177e4SLinus Torvalds clone->next = head->next; 5931da177e4SLinus Torvalds head->next = clone; 5941da177e4SLinus Torvalds skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; 5951da177e4SLinus Torvalds skb_shinfo(head)->frag_list = NULL; 5961da177e4SLinus Torvalds for (i=0; i<skb_shinfo(head)->nr_frags; i++) 5971da177e4SLinus Torvalds plen += skb_shinfo(head)->frags[i].size; 5981da177e4SLinus Torvalds clone->len = clone->data_len = head->data_len - plen; 5991da177e4SLinus Torvalds head->data_len -= clone->len; 6001da177e4SLinus Torvalds head->len -= clone->len; 6011da177e4SLinus Torvalds clone->csum = 0; 6021da177e4SLinus Torvalds clone->ip_summed = head->ip_summed; 6037eb95156SPavel Emelyanov atomic_add(clone->truesize, &ip4_frags.mem); 6041da177e4SLinus Torvalds } 6051da177e4SLinus Torvalds 6061da177e4SLinus Torvalds skb_shinfo(head)->frag_list = head->next; 607d56f90a7SArnaldo Carvalho de Melo skb_push(head, head->data - skb_network_header(head)); 6087eb95156SPavel Emelyanov atomic_sub(head->truesize, &ip4_frags.mem); 6091da177e4SLinus Torvalds 6101da177e4SLinus Torvalds for (fp=head->next; fp; fp = fp->next) { 6111da177e4SLinus Torvalds head->data_len += fp->len; 6121da177e4SLinus Torvalds head->len += fp->len; 6131da177e4SLinus Torvalds if (head->ip_summed != fp->ip_summed) 6141da177e4SLinus Torvalds head->ip_summed = CHECKSUM_NONE; 61584fa7933SPatrick McHardy else if (head->ip_summed == CHECKSUM_COMPLETE) 6161da177e4SLinus Torvalds head->csum = csum_add(head->csum, fp->csum); 6171da177e4SLinus Torvalds head->truesize += fp->truesize; 6187eb95156SPavel Emelyanov atomic_sub(fp->truesize, &ip4_frags.mem); 6191da177e4SLinus Torvalds } 6201da177e4SLinus Torvalds 6211da177e4SLinus Torvalds head->next = NULL; 6221da177e4SLinus Torvalds head->dev = dev; 6235ab11c98SPavel Emelyanov head->tstamp = qp->q.stamp; 6241da177e4SLinus Torvalds 625eddc9ec5SArnaldo Carvalho de Melo iph = ip_hdr(head); 6261da177e4SLinus Torvalds iph->frag_off = 0; 6271da177e4SLinus Torvalds iph->tot_len = htons(len); 6281da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMOKS); 6295ab11c98SPavel Emelyanov qp->q.fragments = NULL; 6301706d587SHerbert Xu return 0; 6311da177e4SLinus Torvalds 6321da177e4SLinus Torvalds out_nomem: 63364ce2073SPatrick McHardy LIMIT_NETDEBUG(KERN_ERR "IP: queue_glue: no memory for gluing " 63464ce2073SPatrick McHardy "queue %p\n", qp); 6351da177e4SLinus Torvalds goto out_fail; 6361da177e4SLinus Torvalds out_oversize: 6371da177e4SLinus Torvalds if (net_ratelimit()) 6381da177e4SLinus Torvalds printk(KERN_INFO 6391da177e4SLinus Torvalds "Oversized IP packet from %d.%d.%d.%d.\n", 6401da177e4SLinus Torvalds NIPQUAD(qp->saddr)); 6411da177e4SLinus Torvalds out_fail: 6421da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 6431706d587SHerbert Xu return err; 6441da177e4SLinus Torvalds } 6451da177e4SLinus Torvalds 6461da177e4SLinus Torvalds /* Process an incoming IP datagram fragment. */ 647776c729eSHerbert Xu int ip_defrag(struct sk_buff *skb, u32 user) 6481da177e4SLinus Torvalds { 6491da177e4SLinus Torvalds struct ipq *qp; 6501da177e4SLinus Torvalds 6511da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMREQDS); 6521da177e4SLinus Torvalds 6531da177e4SLinus Torvalds /* Start by cleaning up the memory. */ 65404128f23SPavel Emelyanov if (atomic_read(&ip4_frags.mem) > ip4_frags_ctl.high_thresh) 6551da177e4SLinus Torvalds ip_evictor(); 6561da177e4SLinus Torvalds 6571da177e4SLinus Torvalds /* Lookup (or create) queue header */ 658eddc9ec5SArnaldo Carvalho de Melo if ((qp = ip_find(ip_hdr(skb), user)) != NULL) { 6591706d587SHerbert Xu int ret; 6601da177e4SLinus Torvalds 6615ab11c98SPavel Emelyanov spin_lock(&qp->q.lock); 6621da177e4SLinus Torvalds 6631706d587SHerbert Xu ret = ip_frag_queue(qp, skb); 6641da177e4SLinus Torvalds 6655ab11c98SPavel Emelyanov spin_unlock(&qp->q.lock); 6664b6cb5d8SPavel Emelyanov ipq_put(qp); 667776c729eSHerbert Xu return ret; 6681da177e4SLinus Torvalds } 6691da177e4SLinus Torvalds 6701da177e4SLinus Torvalds IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); 6711da177e4SLinus Torvalds kfree_skb(skb); 672776c729eSHerbert Xu return -ENOMEM; 6731da177e4SLinus Torvalds } 6741da177e4SLinus Torvalds 675b7aa0bf7SEric Dumazet void __init ipfrag_init(void) 6761da177e4SLinus Torvalds { 67704128f23SPavel Emelyanov ip4_frags.ctl = &ip4_frags_ctl; 678321a3a99SPavel Emelyanov ip4_frags.hashfn = ip4_hashfn; 6791e4b8287SPavel Emelyanov ip4_frags.destructor = ip4_frag_free; 6801e4b8287SPavel Emelyanov ip4_frags.skb_free = NULL; 6811e4b8287SPavel Emelyanov ip4_frags.qsize = sizeof(struct ipq); 6827eb95156SPavel Emelyanov inet_frags_init(&ip4_frags); 6831da177e4SLinus Torvalds } 6841da177e4SLinus Torvalds 6851da177e4SLinus Torvalds EXPORT_SYMBOL(ip_defrag); 686