/* * INET An implementation of the TCP/IP protocol suite for the LINUX * operating system. INET is implemented using the BSD Socket * interface as the means of communication with the user level. * * The User Datagram Protocol (UDP). * * Authors: Ross Biro * Fred N. van Kempen, * Arnt Gulbrandsen, * Alan Cox, * Hirokazu Takahashi, * * Fixes: * Alan Cox : verify_area() calls * Alan Cox : stopped close while in use off icmp * messages. Not a fix but a botch that * for udp at least is 'valid'. * Alan Cox : Fixed icmp handling properly * Alan Cox : Correct error for oversized datagrams * Alan Cox : Tidied select() semantics. * Alan Cox : udp_err() fixed properly, also now * select and read wake correctly on errors * Alan Cox : udp_send verify_area moved to avoid mem leak * Alan Cox : UDP can count its memory * Alan Cox : send to an unknown connection causes * an ECONNREFUSED off the icmp, but * does NOT close. * Alan Cox : Switched to new sk_buff handlers. No more backlog! * Alan Cox : Using generic datagram code. Even smaller and the PEEK * bug no longer crashes it. * Fred Van Kempen : Net2e support for sk->broadcast. * Alan Cox : Uses skb_free_datagram * Alan Cox : Added get/set sockopt support. * Alan Cox : Broadcasting without option set returns EACCES. * Alan Cox : No wakeup calls. Instead we now use the callbacks. * Alan Cox : Use ip_tos and ip_ttl * Alan Cox : SNMP Mibs * Alan Cox : MSG_DONTROUTE, and 0.0.0.0 support. * Matt Dillon : UDP length checks. * Alan Cox : Smarter af_inet used properly. * Alan Cox : Use new kernel side addressing. * Alan Cox : Incorrect return on truncated datagram receive. * Arnt Gulbrandsen : New udp_send and stuff * Alan Cox : Cache last socket * Alan Cox : Route cache * Jon Peatfield : Minor efficiency fix to sendto(). * Mike Shaver : RFC1122 checks. * Alan Cox : Nonblocking error fix. * Willy Konynenberg : Transparent proxying support. * Mike McLagan : Routing by source * David S. Miller : New socket lookup architecture. * Last socket cache retained as it * does have a high hit rate. * Olaf Kirch : Don't linearise iovec on sendmsg. * Andi Kleen : Some cleanups, cache destination entry * for connect. * Vitaly E. Lavrov : Transparent proxy revived after year coma. * Melvin Smith : Check msg_name not msg_namelen in sendto(), * return ENOTCONN for unconnected sockets (POSIX) * Janos Farkas : don't deliver multi/broadcasts to a different * bound-to-device socket * Hirokazu Takahashi : HW checksumming for outgoing UDP * datagrams. * Hirokazu Takahashi : sendfile() on UDP works now. * Arnaldo C. Melo : convert /proc/net/udp to seq_file * YOSHIFUJI Hideaki @USAGI and: Support IPV6_V6ONLY socket option, which * Alexey Kuznetsov: allow both IPv4 and IPv6 sockets to bind * a single port at the same time. * Derek Atkins : Add Encapulation Support * James Chapman : Add L2TP encapsulation type. * * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #define pr_fmt(fmt) "UDP: " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "udp_impl.h" struct udp_table udp_table __read_mostly; EXPORT_SYMBOL(udp_table); long sysctl_udp_mem[3] __read_mostly; EXPORT_SYMBOL(sysctl_udp_mem); int sysctl_udp_rmem_min __read_mostly; EXPORT_SYMBOL(sysctl_udp_rmem_min); int sysctl_udp_wmem_min __read_mostly; EXPORT_SYMBOL(sysctl_udp_wmem_min); atomic_long_t udp_memory_allocated; EXPORT_SYMBOL(udp_memory_allocated); #define MAX_UDP_PORTS 65536 #define PORTS_PER_CHAIN (MAX_UDP_PORTS / UDP_HTABLE_SIZE_MIN) static int udp_lib_lport_inuse(struct net *net, __u16 num, const struct udp_hslot *hslot, unsigned long *bitmap, struct sock *sk, int (*saddr_comp)(const struct sock *sk1, const struct sock *sk2), unsigned int log) { struct sock *sk2; struct hlist_nulls_node *node; kuid_t uid = sock_i_uid(sk); sk_nulls_for_each(sk2, node, &hslot->head) if (net_eq(sock_net(sk2), net) && sk2 != sk && (bitmap || udp_sk(sk2)->udp_port_hash == num) && (!sk2->sk_reuse || !sk->sk_reuse) && (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if || sk2->sk_bound_dev_if == sk->sk_bound_dev_if) && (!sk2->sk_reuseport || !sk->sk_reuseport || !uid_eq(uid, sock_i_uid(sk2))) && (*saddr_comp)(sk, sk2)) { if (bitmap) __set_bit(udp_sk(sk2)->udp_port_hash >> log, bitmap); else return 1; } return 0; } /* * Note: we still hold spinlock of primary hash chain, so no other writer * can insert/delete a socket with local_port == num */ static int udp_lib_lport_inuse2(struct net *net, __u16 num, struct udp_hslot *hslot2, struct sock *sk, int (*saddr_comp)(const struct sock *sk1, const struct sock *sk2)) { struct sock *sk2; struct hlist_nulls_node *node; kuid_t uid = sock_i_uid(sk); int res = 0; spin_lock(&hslot2->lock); udp_portaddr_for_each_entry(sk2, node, &hslot2->head) if (net_eq(sock_net(sk2), net) && sk2 != sk && (udp_sk(sk2)->udp_port_hash == num) && (!sk2->sk_reuse || !sk->sk_reuse) && (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if || sk2->sk_bound_dev_if == sk->sk_bound_dev_if) && (!sk2->sk_reuseport || !sk->sk_reuseport || !uid_eq(uid, sock_i_uid(sk2))) && (*saddr_comp)(sk, sk2)) { res = 1; break; } spin_unlock(&hslot2->lock); return res; } /** * udp_lib_get_port - UDP/-Lite port lookup for IPv4 and IPv6 * * @sk: socket struct in question * @snum: port number to look up * @saddr_comp: AF-dependent comparison of bound local IP addresses * @hash2_nulladdr: AF-dependent hash value in secondary hash chains, * with NULL address */ int udp_lib_get_port(struct sock *sk, unsigned short snum, int (*saddr_comp)(const struct sock *sk1, const struct sock *sk2), unsigned int hash2_nulladdr) { struct udp_hslot *hslot, *hslot2; struct udp_table *udptable = sk->sk_prot->h.udp_table; int error = 1; struct net *net = sock_net(sk); if (!snum) { int low, high, remaining; unsigned int rand; unsigned short first, last; DECLARE_BITMAP(bitmap, PORTS_PER_CHAIN); inet_get_local_port_range(net, &low, &high); remaining = (high - low) + 1; rand = prandom_u32(); first = (((u64)rand * remaining) >> 32) + low; /* * force rand to be an odd multiple of UDP_HTABLE_SIZE */ rand = (rand | 1) * (udptable->mask + 1); last = first + udptable->mask + 1; do { hslot = udp_hashslot(udptable, net, first); bitmap_zero(bitmap, PORTS_PER_CHAIN); spin_lock_bh(&hslot->lock); udp_lib_lport_inuse(net, snum, hslot, bitmap, sk, saddr_comp, udptable->log); snum = first; /* * Iterate on all possible values of snum for this hash. * Using steps of an odd multiple of UDP_HTABLE_SIZE * give us randomization and full range coverage. */ do { if (low <= snum && snum <= high && !test_bit(snum >> udptable->log, bitmap) && !inet_is_local_reserved_port(net, snum)) goto found; snum += rand; } while (snum != first); spin_unlock_bh(&hslot->lock); } while (++first != last); goto fail; } else { hslot = udp_hashslot(udptable, net, snum); spin_lock_bh(&hslot->lock); if (hslot->count > 10) { int exist; unsigned int slot2 = udp_sk(sk)->udp_portaddr_hash ^ snum; slot2 &= udptable->mask; hash2_nulladdr &= udptable->mask; hslot2 = udp_hashslot2(udptable, slot2); if (hslot->count < hslot2->count) goto scan_primary_hash; exist = udp_lib_lport_inuse2(net, snum, hslot2, sk, saddr_comp); if (!exist && (hash2_nulladdr != slot2)) { hslot2 = udp_hashslot2(udptable, hash2_nulladdr); exist = udp_lib_lport_inuse2(net, snum, hslot2, sk, saddr_comp); } if (exist) goto fail_unlock; else goto found; } scan_primary_hash: if (udp_lib_lport_inuse(net, snum, hslot, NULL, sk, saddr_comp, 0)) goto fail_unlock; } found: inet_sk(sk)->inet_num = snum; udp_sk(sk)->udp_port_hash = snum; udp_sk(sk)->udp_portaddr_hash ^= snum; if (sk_unhashed(sk)) { sk_nulls_add_node_rcu(sk, &hslot->head); hslot->count++; sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1); hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash); spin_lock(&hslot2->lock); hlist_nulls_add_head_rcu(&udp_sk(sk)->udp_portaddr_node, &hslot2->head); hslot2->count++; spin_unlock(&hslot2->lock); } error = 0; fail_unlock: spin_unlock_bh(&hslot->lock); fail: return error; } EXPORT_SYMBOL(udp_lib_get_port); static int ipv4_rcv_saddr_equal(const struct sock *sk1, const struct sock *sk2) { struct inet_sock *inet1 = inet_sk(sk1), *inet2 = inet_sk(sk2); return (!ipv6_only_sock(sk2) && (!inet1->inet_rcv_saddr || !inet2->inet_rcv_saddr || inet1->inet_rcv_saddr == inet2->inet_rcv_saddr)); } static unsigned int udp4_portaddr_hash(struct net *net, __be32 saddr, unsigned int port) { return jhash_1word((__force u32)saddr, net_hash_mix(net)) ^ port; } int udp_v4_get_port(struct sock *sk, unsigned short snum) { unsigned int hash2_nulladdr = udp4_portaddr_hash(sock_net(sk), htonl(INADDR_ANY), snum); unsigned int hash2_partial = udp4_portaddr_hash(sock_net(sk), inet_sk(sk)->inet_rcv_saddr, 0); /* precompute partial secondary hash */ udp_sk(sk)->udp_portaddr_hash = hash2_partial; return udp_lib_get_port(sk, snum, ipv4_rcv_saddr_equal, hash2_nulladdr); } static inline int compute_score(struct sock *sk, struct net *net, __be32 saddr, unsigned short hnum, __be16 sport, __be32 daddr, __be16 dport, int dif) { int score = -1; if (net_eq(sock_net(sk), net) && udp_sk(sk)->udp_port_hash == hnum && !ipv6_only_sock(sk)) { struct inet_sock *inet = inet_sk(sk); score = (sk->sk_family == PF_INET ? 2 : 1); if (inet->inet_rcv_saddr) { if (inet->inet_rcv_saddr != daddr) return -1; score += 4; } if (inet->inet_daddr) { if (inet->inet_daddr != saddr) return -1; score += 4; } if (inet->inet_dport) { if (inet->inet_dport != sport) return -1; score += 4; } if (sk->sk_bound_dev_if) { if (sk->sk_bound_dev_if != dif) return -1; score += 4; } } return score; } /* * In this second variant, we check (daddr, dport) matches (inet_rcv_sadd, inet_num) */ static inline int compute_score2(struct sock *sk, struct net *net, __be32 saddr, __be16 sport, __be32 daddr, unsigned int hnum, int dif) { int score = -1; if (net_eq(sock_net(sk), net) && !ipv6_only_sock(sk)) { struct inet_sock *inet = inet_sk(sk); if (inet->inet_rcv_saddr != daddr) return -1; if (inet->inet_num != hnum) return -1; score = (sk->sk_family == PF_INET ? 2 : 1); if (inet->inet_daddr) { if (inet->inet_daddr != saddr) return -1; score += 4; } if (inet->inet_dport) { if (inet->inet_dport != sport) return -1; score += 4; } if (sk->sk_bound_dev_if) { if (sk->sk_bound_dev_if != dif) return -1; score += 4; } } return score; } static unsigned int udp_ehashfn(struct net *net, const __be32 laddr, const __u16 lport, const __be32 faddr, const __be16 fport) { static u32 udp_ehash_secret __read_mostly; net_get_random_once(&udp_ehash_secret, sizeof(udp_ehash_secret)); return __inet_ehashfn(laddr, lport, faddr, fport, udp_ehash_secret + net_hash_mix(net)); } /* called with read_rcu_lock() */ static struct sock *udp4_lib_lookup2(struct net *net, __be32 saddr, __be16 sport, __be32 daddr, unsigned int hnum, int dif, struct udp_hslot *hslot2, unsigned int slot2) { struct sock *sk, *result; struct hlist_nulls_node *node; int score, badness, matches = 0, reuseport = 0; u32 hash = 0; begin: result = NULL; badness = 0; udp_portaddr_for_each_entry_rcu(sk, node, &hslot2->head) { score = compute_score2(sk, net, saddr, sport, daddr, hnum, dif); if (score > badness) { result = sk; badness = score; reuseport = sk->sk_reuseport; if (reuseport) { hash = udp_ehashfn(net, daddr, hnum, saddr, sport); matches = 1; } } else if (score == badness && reuseport) { matches++; if (((u64)hash * matches) >> 32 == 0) result = sk; hash = next_pseudo_random32(hash); } } /* * if the nulls value we got at the end of this lookup is * not the expected one, we must restart lookup. * We probably met an item that was moved to another chain. */ if (get_nulls_value(node) != slot2) goto begin; if (result) { if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2))) result = NULL; else if (unlikely(compute_score2(result, net, saddr, sport, daddr, hnum, dif) < badness)) { sock_put(result); goto begin; } } return result; } /* UDP is nearly always wildcards out the wazoo, it makes no sense to try * harder than this. -DaveM */ struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport, __be32 daddr, __be16 dport, int dif, struct udp_table *udptable) { struct sock *sk, *result; struct hlist_nulls_node *node; unsigned short hnum = ntohs(dport); unsigned int hash2, slot2, slot = udp_hashfn(net, hnum, udptable->mask); struct udp_hslot *hslot2, *hslot = &udptable->hash[slot]; int score, badness, matches = 0, reuseport = 0; u32 hash = 0; rcu_read_lock(); if (hslot->count > 10) { hash2 = udp4_portaddr_hash(net, daddr, hnum); slot2 = hash2 & udptable->mask; hslot2 = &udptable->hash2[slot2]; if (hslot->count < hslot2->count) goto begin; result = udp4_lib_lookup2(net, saddr, sport, daddr, hnum, dif, hslot2, slot2); if (!result) { hash2 = udp4_portaddr_hash(net, htonl(INADDR_ANY), hnum); slot2 = hash2 & udptable->mask; hslot2 = &udptable->hash2[slot2]; if (hslot->count < hslot2->count) goto begin; result = udp4_lib_lookup2(net, saddr, sport, htonl(INADDR_ANY), hnum, dif, hslot2, slot2); } rcu_read_unlock(); return result; } begin: result = NULL; badness = 0; sk_nulls_for_each_rcu(sk, node, &hslot->head) { score = compute_score(sk, net, saddr, hnum, sport, daddr, dport, dif); if (score > badness) { result = sk; badness = score; reuseport = sk->sk_reuseport; if (reuseport) { hash = udp_ehashfn(net, daddr, hnum, saddr, sport); matches = 1; } } else if (score == badness && reuseport) { matches++; if (((u64)hash * matches) >> 32 == 0) result = sk; hash = next_pseudo_random32(hash); } } /* * if the nulls value we got at the end of this lookup is * not the expected one, we must restart lookup. * We probably met an item that was moved to another chain. */ if (get_nulls_value(node) != slot) goto begin; if (result) { if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2))) result = NULL; else if (unlikely(compute_score(result, net, saddr, hnum, sport, daddr, dport, dif) < badness)) { sock_put(result); goto begin; } } rcu_read_unlock(); return result; } EXPORT_SYMBOL_GPL(__udp4_lib_lookup); static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb, __be16 sport, __be16 dport, struct udp_table *udptable) { const struct iphdr *iph = ip_hdr(skb); return __udp4_lib_lookup(dev_net(skb_dst(skb)->dev), iph->saddr, sport, iph->daddr, dport, inet_iif(skb), udptable); } struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport, __be32 daddr, __be16 dport, int dif) { return __udp4_lib_lookup(net, saddr, sport, daddr, dport, dif, &udp_table); } EXPORT_SYMBOL_GPL(udp4_lib_lookup); static inline bool __udp_is_mcast_sock(struct net *net, struct sock *sk, __be16 loc_port, __be32 loc_addr, __be16 rmt_port, __be32 rmt_addr, int dif, unsigned short hnum) { struct inet_sock *inet = inet_sk(sk); if (!net_eq(sock_net(sk), net) || udp_sk(sk)->udp_port_hash != hnum || (inet->inet_daddr && inet->inet_daddr != rmt_addr) || (inet->inet_dport != rmt_port && inet->inet_dport) || (inet->inet_rcv_saddr && inet->inet_rcv_saddr != loc_addr) || ipv6_only_sock(sk) || (sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif)) return false; if (!ip_mc_sf_allow(sk, loc_addr, rmt_addr, dif)) return false; return true; } static inline struct sock *udp_v4_mcast_next(struct net *net, struct sock *sk, __be16 loc_port, __be32 loc_addr, __be16 rmt_port, __be32 rmt_addr, int dif) { struct hlist_nulls_node *node; struct sock *s = sk; unsigned short hnum = ntohs(loc_port); sk_nulls_for_each_from(s, node) { if (__udp_is_mcast_sock(net, s, loc_port, loc_addr, rmt_port, rmt_addr, dif, hnum)) goto found; } s = NULL; found: return s; } /* * This routine is called by the ICMP module when it gets some * sort of error condition. If err < 0 then the socket should * be closed and the error returned to the user. If err > 0 * it's just the icmp type << 8 | icmp code. * Header points to the ip header of the error packet. We move * on past this. Then (as it used to claim before adjustment) * header points to the first 8 bytes of the udp header. We need * to find the appropriate port. */ void __udp4_lib_err(struct sk_buff *skb, u32 info, struct udp_table *udptable) { struct inet_sock *inet; const struct iphdr *iph = (const struct iphdr *)skb->data; struct udphdr *uh = (struct udphdr *)(skb->data+(iph->ihl<<2)); const int type = icmp_hdr(skb)->type; const int code = icmp_hdr(skb)->code; struct sock *sk; int harderr; int err; struct net *net = dev_net(skb->dev); sk = __udp4_lib_lookup(net, iph->daddr, uh->dest, iph->saddr, uh->source, skb->dev->ifindex, udptable); if (sk == NULL) { ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); return; /* No socket for error */ } err = 0; harderr = 0; inet = inet_sk(sk); switch (type) { default: case ICMP_TIME_EXCEEDED: err = EHOSTUNREACH; break; case ICMP_SOURCE_QUENCH: goto out; case ICMP_PARAMETERPROB: err = EPROTO; harderr = 1; break; case ICMP_DEST_UNREACH: if (code == ICMP_FRAG_NEEDED) { /* Path MTU discovery */ ipv4_sk_update_pmtu(skb, sk, info); if (inet->pmtudisc != IP_PMTUDISC_DONT) { err = EMSGSIZE; harderr = 1; break; } goto out; } err = EHOSTUNREACH; if (code <= NR_ICMP_UNREACH) { harderr = icmp_err_convert[code].fatal; err = icmp_err_convert[code].errno; } break; case ICMP_REDIRECT: ipv4_sk_redirect(skb, sk); goto out; } /* * RFC1122: OK. Passes ICMP errors back to application, as per * 4.1.3.3. */ if (!inet->recverr) { if (!harderr || sk->sk_state != TCP_ESTABLISHED) goto out; } else ip_icmp_error(sk, skb, err, uh->dest, info, (u8 *)(uh+1)); sk->sk_err = err; sk->sk_error_report(sk); out: sock_put(sk); } void udp_err(struct sk_buff *skb, u32 info) { __udp4_lib_err(skb, info, &udp_table); } /* * Throw away all pending data and cancel the corking. Socket is locked. */ void udp_flush_pending_frames(struct sock *sk) { struct udp_sock *up = udp_sk(sk); if (up->pending) { up->len = 0; up->pending = 0; ip_flush_pending_frames(sk); } } EXPORT_SYMBOL(udp_flush_pending_frames); /** * udp4_hwcsum - handle outgoing HW checksumming * @skb: sk_buff containing the filled-in UDP header * (checksum field must be zeroed out) * @src: source IP address * @dst: destination IP address */ void udp4_hwcsum(struct sk_buff *skb, __be32 src, __be32 dst) { struct udphdr *uh = udp_hdr(skb); struct sk_buff *frags = skb_shinfo(skb)->frag_list; int offset = skb_transport_offset(skb); int len = skb->len - offset; int hlen = len; __wsum csum = 0; if (!frags) { /* * Only one fragment on the socket. */ skb->csum_start = skb_transport_header(skb) - skb->head; skb->csum_offset = offsetof(struct udphdr, check); uh->check = ~csum_tcpudp_magic(src, dst, len, IPPROTO_UDP, 0); } else { /* * HW-checksum won't work as there are two or more * fragments on the socket so that all csums of sk_buffs * should be together */ do { csum = csum_add(csum, frags->csum); hlen -= frags->len; } while ((frags = frags->next)); csum = skb_checksum(skb, offset, hlen, csum); skb->ip_summed = CHECKSUM_NONE; uh->check = csum_tcpudp_magic(src, dst, len, IPPROTO_UDP, csum); if (uh->check == 0) uh->check = CSUM_MANGLED_0; } } EXPORT_SYMBOL_GPL(udp4_hwcsum); /* Function to set UDP checksum for an IPv4 UDP packet. This is intended * for the simple case like when setting the checksum for a UDP tunnel. */ void udp_set_csum(bool nocheck, struct sk_buff *skb, __be32 saddr, __be32 daddr, int len) { struct udphdr *uh = udp_hdr(skb); if (nocheck) uh->check = 0; else if (skb_is_gso(skb)) uh->check = ~udp_v4_check(len, saddr, daddr, 0); else if (skb_dst(skb) && skb_dst(skb)->dev && (skb_dst(skb)->dev->features & NETIF_F_V4_CSUM)) { BUG_ON(skb->ip_summed == CHECKSUM_PARTIAL); skb->ip_summed = CHECKSUM_PARTIAL; skb->csum_start = skb_transport_header(skb) - skb->head; skb->csum_offset = offsetof(struct udphdr, check); uh->check = ~udp_v4_check(len, saddr, daddr, 0); } else { __wsum csum; BUG_ON(skb->ip_summed == CHECKSUM_PARTIAL); uh->check = 0; csum = skb_checksum(skb, 0, len, 0); uh->check = udp_v4_check(len, saddr, daddr, csum); if (uh->check == 0) uh->check = CSUM_MANGLED_0; skb->ip_summed = CHECKSUM_UNNECESSARY; } } EXPORT_SYMBOL(udp_set_csum); static int udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4) { struct sock *sk = skb->sk; struct inet_sock *inet = inet_sk(sk); struct udphdr *uh; int err = 0; int is_udplite = IS_UDPLITE(sk); int offset = skb_transport_offset(skb); int len = skb->len - offset; __wsum csum = 0; /* * Create a UDP header */ uh = udp_hdr(skb); uh->source = inet->inet_sport; uh->dest = fl4->fl4_dport; uh->len = htons(len); uh->check = 0; if (is_udplite) /* UDP-Lite */ csum = udplite_csum(skb); else if (sk->sk_no_check_tx) { /* UDP csum disabled */ skb->ip_summed = CHECKSUM_NONE; goto send; } else if (skb->ip_summed == CHECKSUM_PARTIAL) { /* UDP hardware csum */ udp4_hwcsum(skb, fl4->saddr, fl4->daddr); goto send; } else csum = udp_csum(skb); /* add protocol-dependent pseudo-header */ uh->check = csum_tcpudp_magic(fl4->saddr, fl4->daddr, len, sk->sk_protocol, csum); if (uh->check == 0) uh->check = CSUM_MANGLED_0; send: err = ip_send_skb(sock_net(sk), skb); if (err) { if (err == -ENOBUFS && !inet->recverr) { UDP_INC_STATS_USER(sock_net(sk), UDP_MIB_SNDBUFERRORS, is_udplite); err = 0; } } else UDP_INC_STATS_USER(sock_net(sk), UDP_MIB_OUTDATAGRAMS, is_udplite); return err; } /* * Push out all pending data as one UDP datagram. Socket is locked. */ int udp_push_pending_frames(struct sock *sk) { struct udp_sock *up = udp_sk(sk); struct inet_sock *inet = inet_sk(sk); struct flowi4 *fl4 = &inet->cork.fl.u.ip4; struct sk_buff *skb; int err = 0; skb = ip_finish_skb(sk, fl4); if (!skb) goto out; err = udp_send_skb(skb, fl4); out: up->len = 0; up->pending = 0; return err; } EXPORT_SYMBOL(udp_push_pending_frames); int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, size_t len) { struct inet_sock *inet = inet_sk(sk); struct udp_sock *up = udp_sk(sk); struct flowi4 fl4_stack; struct flowi4 *fl4; int ulen = len; struct ipcm_cookie ipc; struct rtable *rt = NULL; int free = 0; int connected = 0; __be32 daddr, faddr, saddr; __be16 dport; u8 tos; int err, is_udplite = IS_UDPLITE(sk); int corkreq = up->corkflag || msg->msg_flags&MSG_MORE; int (*getfrag)(void *, char *, int, int, int, struct sk_buff *); struct sk_buff *skb; struct ip_options_data opt_copy; if (len > 0xFFFF) return -EMSGSIZE; /* * Check the flags. */ if (msg->msg_flags & MSG_OOB) /* Mirror BSD error message compatibility */ return -EOPNOTSUPP; ipc.opt = NULL; ipc.tx_flags = 0; ipc.ttl = 0; ipc.tos = -1; getfrag = is_udplite ? udplite_getfrag : ip_generic_getfrag; fl4 = &inet->cork.fl.u.ip4; if (up->pending) { /* * There are pending frames. * The socket lock must be held while it's corked. */ lock_sock(sk); if (likely(up->pending)) { if (unlikely(up->pending != AF_INET)) { release_sock(sk); return -EINVAL; } goto do_append_data; } release_sock(sk); } ulen += sizeof(struct udphdr); /* * Get and verify the address. */ if (msg->msg_name) { DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name); if (msg->msg_namelen < sizeof(*usin)) return -EINVAL; if (usin->sin_family != AF_INET) { if (usin->sin_family != AF_UNSPEC) return -EAFNOSUPPORT; } daddr = usin->sin_addr.s_addr; dport = usin->sin_port; if (dport == 0) return -EINVAL; } else { if (sk->sk_state != TCP_ESTABLISHED) return -EDESTADDRREQ; daddr = inet->inet_daddr; dport = inet->inet_dport; /* Open fast path for connected socket. Route will not be used, if at least one option is set. */ connected = 1; } ipc.addr = inet->inet_saddr; ipc.oif = sk->sk_bound_dev_if; sock_tx_timestamp(sk, &ipc.tx_flags); if (msg->msg_controllen) { err = ip_cmsg_send(sock_net(sk), msg, &ipc, sk->sk_family == AF_INET6); if (err) return err; if (ipc.opt) free = 1; connected = 0; } if (!ipc.opt) { struct ip_options_rcu *inet_opt; rcu_read_lock(); inet_opt = rcu_dereference(inet->inet_opt); if (inet_opt) { memcpy(&opt_copy, inet_opt, sizeof(*inet_opt) + inet_opt->opt.optlen); ipc.opt = &opt_copy.opt; } rcu_read_unlock(); } saddr = ipc.addr; ipc.addr = faddr = daddr; if (ipc.opt && ipc.opt->opt.srr) { if (!daddr) return -EINVAL; faddr = ipc.opt->opt.faddr; connected = 0; } tos = get_rttos(&ipc, inet); if (sock_flag(sk, SOCK_LOCALROUTE) || (msg->msg_flags & MSG_DONTROUTE) || (ipc.opt && ipc.opt->opt.is_strictroute)) { tos |= RTO_ONLINK; connected = 0; } if (ipv4_is_multicast(daddr)) { if (!ipc.oif) ipc.oif = inet->mc_index; if (!saddr) saddr = inet->mc_addr; connected = 0; } else if (!ipc.oif) ipc.oif = inet->uc_index; if (connected) rt = (struct rtable *)sk_dst_check(sk, 0); if (rt == NULL) { struct net *net = sock_net(sk); fl4 = &fl4_stack; flowi4_init_output(fl4, ipc.oif, sk->sk_mark, tos, RT_SCOPE_UNIVERSE, sk->sk_protocol, inet_sk_flowi_flags(sk), faddr, saddr, dport, inet->inet_sport); security_sk_classify_flow(sk, flowi4_to_flowi(fl4)); rt = ip_route_output_flow(net, fl4, sk); if (IS_ERR(rt)) { err = PTR_ERR(rt); rt = NULL; if (err == -ENETUNREACH) IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); goto out; } err = -EACCES; if ((rt->rt_flags & RTCF_BROADCAST) && !sock_flag(sk, SOCK_BROADCAST)) goto out; if (connected) sk_dst_set(sk, dst_clone(&rt->dst)); } if (msg->msg_flags&MSG_CONFIRM) goto do_confirm; back_from_confirm: saddr = fl4->saddr; if (!ipc.addr) daddr = ipc.addr = fl4->daddr; /* Lockless fast path for the non-corking case. */ if (!corkreq) { skb = ip_make_skb(sk, fl4, getfrag, msg->msg_iov, ulen, sizeof(struct udphdr), &ipc, &rt, msg->msg_flags); err = PTR_ERR(skb); if (!IS_ERR_OR_NULL(skb)) err = udp_send_skb(skb, fl4); goto out; } lock_sock(sk); if (unlikely(up->pending)) { /* The socket is already corked while preparing it. */ /* ... which is an evident application bug. --ANK */ release_sock(sk); LIMIT_NETDEBUG(KERN_DEBUG pr_fmt("cork app bug 2\n")); err = -EINVAL; goto out; } /* * Now cork the socket to pend data. */ fl4 = &inet->cork.fl.u.ip4; fl4->daddr = daddr; fl4->saddr = saddr; fl4->fl4_dport = dport; fl4->fl4_sport = inet->inet_sport; up->pending = AF_INET; do_append_data: up->len += ulen; err = ip_append_data(sk, fl4, getfrag, msg->msg_iov, ulen, sizeof(struct udphdr), &ipc, &rt, corkreq ? msg->msg_flags|MSG_MORE : msg->msg_flags); if (err) udp_flush_pending_frames(sk); else if (!corkreq) err = udp_push_pending_frames(sk); else if (unlikely(skb_queue_empty(&sk->sk_write_queue))) up->pending = 0; release_sock(sk); out: ip_rt_put(rt); if (free) kfree(ipc.opt); if (!err) return len; /* * ENOBUFS = no kernel mem, SOCK_NOSPACE = no sndbuf space. Reporting * ENOBUFS might not be good (it's not tunable per se), but otherwise * we don't have a good statistic (IpOutDiscards but it can be too many * things). We could add another new stat but at least for now that * seems like overkill. */ if (err == -ENOBUFS || test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { UDP_INC_STATS_USER(sock_net(sk), UDP_MIB_SNDBUFERRORS, is_udplite); } return err; do_confirm: dst_confirm(&rt->dst); if (!(msg->msg_flags&MSG_PROBE) || len) goto back_from_confirm; err = 0; goto out; } EXPORT_SYMBOL(udp_sendmsg); int udp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, int flags) { struct inet_sock *inet = inet_sk(sk); struct udp_sock *up = udp_sk(sk); int ret; if (flags & MSG_SENDPAGE_NOTLAST) flags |= MSG_MORE; if (!up->pending) { struct msghdr msg = { .msg_flags = flags|MSG_MORE }; /* Call udp_sendmsg to specify destination address which * sendpage interface can't pass. * This will succeed only when the socket is connected. */ ret = udp_sendmsg(NULL, sk, &msg, 0); if (ret < 0) return ret; } lock_sock(sk); if (unlikely(!up->pending)) { release_sock(sk); LIMIT_NETDEBUG(KERN_DEBUG pr_fmt("udp cork app bug 3\n")); return -EINVAL; } ret = ip_append_page(sk, &inet->cork.fl.u.ip4, page, offset, size, flags); if (ret == -EOPNOTSUPP) { release_sock(sk); return sock_no_sendpage(sk->sk_socket, page, offset, size, flags); } if (ret < 0) { udp_flush_pending_frames(sk); goto out; } up->len += size; if (!(up->corkflag || (flags&MSG_MORE))) ret = udp_push_pending_frames(sk); if (!ret) ret = size; out: release_sock(sk); return ret; } /** * first_packet_length - return length of first packet in receive queue * @sk: socket * * Drops all bad checksum frames, until a valid one is found. * Returns the length of found skb, or 0 if none is found. */ static unsigned int first_packet_length(struct sock *sk) { struct sk_buff_head list_kill, *rcvq = &sk->sk_receive_queue; struct sk_buff *skb; unsigned int res; __skb_queue_head_init(&list_kill); spin_lock_bh(&rcvq->lock); while ((skb = skb_peek(rcvq)) != NULL && udp_lib_checksum_complete(skb)) { UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_CSUMERRORS, IS_UDPLITE(sk)); UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_INERRORS, IS_UDPLITE(sk)); atomic_inc(&sk->sk_drops); __skb_unlink(skb, rcvq); __skb_queue_tail(&list_kill, skb); } res = skb ? skb->len : 0; spin_unlock_bh(&rcvq->lock); if (!skb_queue_empty(&list_kill)) { bool slow = lock_sock_fast(sk); __skb_queue_purge(&list_kill); sk_mem_reclaim_partial(sk); unlock_sock_fast(sk, slow); } return res; } /* * IOCTL requests applicable to the UDP protocol */ int udp_ioctl(struct sock *sk, int cmd, unsigned long arg) { switch (cmd) { case SIOCOUTQ: { int amount = sk_wmem_alloc_get(sk); return put_user(amount, (int __user *)arg); } case SIOCINQ: { unsigned int amount = first_packet_length(sk); if (amount) /* * We will only return the amount * of this packet since that is all * that will be read. */ amount -= sizeof(struct udphdr); return put_user(amount, (int __user *)arg); } default: return -ENOIOCTLCMD; } return 0; } EXPORT_SYMBOL(udp_ioctl); /* * This should be easy, if there is something there we * return it, otherwise we block. */ int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, size_t len, int noblock, int flags, int *addr_len) { struct inet_sock *inet = inet_sk(sk); DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name); struct sk_buff *skb; unsigned int ulen, copied; int peeked, off = 0; int err; int is_udplite = IS_UDPLITE(sk); bool slow; if (flags & MSG_ERRQUEUE) return ip_recv_error(sk, msg, len, addr_len); try_again: skb = __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0), &peeked, &off, &err); if (!skb) goto out; ulen = skb->len - sizeof(struct udphdr); copied = len; if (copied > ulen) copied = ulen; else if (copied < ulen) msg->msg_flags |= MSG_TRUNC; /* * If checksum is needed at all, try to do it while copying the * data. If the data is truncated, or if we only want a partial * coverage checksum (UDP-Lite), do it before the copy. */ if (copied < ulen || UDP_SKB_CB(skb)->partial_cov) { if (udp_lib_checksum_complete(skb)) goto csum_copy_err; } if (skb_csum_unnecessary(skb)) err = skb_copy_datagram_iovec(skb, sizeof(struct udphdr), msg->msg_iov, copied); else { err = skb_copy_and_csum_datagram_iovec(skb, sizeof(struct udphdr), msg->msg_iov); if (err == -EINVAL) goto csum_copy_err; } if (unlikely(err)) { trace_kfree_skb(skb, udp_recvmsg); if (!peeked) { atomic_inc(&sk->sk_drops); UDP_INC_STATS_USER(sock_net(sk), UDP_MIB_INERRORS, is_udplite); } goto out_free; } if (!peeked) UDP_INC_STATS_USER(sock_net(sk), UDP_MIB_INDATAGRAMS, is_udplite); sock_recv_ts_and_drops(msg, sk, skb); /* Copy the address. */ if (sin) { sin->sin_family = AF_INET; sin->sin_port = udp_hdr(skb)->source; sin->sin_addr.s_addr = ip_hdr(skb)->saddr; memset(sin->sin_zero, 0, sizeof(sin->sin_zero)); *addr_len = sizeof(*sin); } if (inet->cmsg_flags) ip_cmsg_recv(msg, skb); err = copied; if (flags & MSG_TRUNC) err = ulen; out_free: skb_free_datagram_locked(sk, skb); out: return err; csum_copy_err: slow = lock_sock_fast(sk); if (!skb_kill_datagram(sk, skb, flags)) { UDP_INC_STATS_USER(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite); UDP_INC_STATS_USER(sock_net(sk), UDP_MIB_INERRORS, is_udplite); } unlock_sock_fast(sk, slow); if (noblock) return -EAGAIN; /* starting over for a new packet */ msg->msg_flags &= ~MSG_TRUNC; goto try_again; } int udp_disconnect(struct sock *sk, int flags) { struct inet_sock *inet = inet_sk(sk); /* * 1003.1g - break association. */ sk->sk_state = TCP_CLOSE; inet->inet_daddr = 0; inet->inet_dport = 0; sock_rps_reset_rxhash(sk); sk->sk_bound_dev_if = 0; if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK)) inet_reset_saddr(sk); if (!(sk->sk_userlocks & SOCK_BINDPORT_LOCK)) { sk->sk_prot->unhash(sk); inet->inet_sport = 0; } sk_dst_reset(sk); return 0; } EXPORT_SYMBOL(udp_disconnect); void udp_lib_unhash(struct sock *sk) { if (sk_hashed(sk)) { struct udp_table *udptable = sk->sk_prot->h.udp_table; struct udp_hslot *hslot, *hslot2; hslot = udp_hashslot(udptable, sock_net(sk), udp_sk(sk)->udp_port_hash); hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash); spin_lock_bh(&hslot->lock); if (sk_nulls_del_node_init_rcu(sk)) { hslot->count--; inet_sk(sk)->inet_num = 0; sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1); spin_lock(&hslot2->lock); hlist_nulls_del_init_rcu(&udp_sk(sk)->udp_portaddr_node); hslot2->count--; spin_unlock(&hslot2->lock); } spin_unlock_bh(&hslot->lock); } } EXPORT_SYMBOL(udp_lib_unhash); /* * inet_rcv_saddr was changed, we must rehash secondary hash */ void udp_lib_rehash(struct sock *sk, u16 newhash) { if (sk_hashed(sk)) { struct udp_table *udptable = sk->sk_prot->h.udp_table; struct udp_hslot *hslot, *hslot2, *nhslot2; hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash); nhslot2 = udp_hashslot2(udptable, newhash); udp_sk(sk)->udp_portaddr_hash = newhash; if (hslot2 != nhslot2) { hslot = udp_hashslot(udptable, sock_net(sk), udp_sk(sk)->udp_port_hash); /* we must lock primary chain too */ spin_lock_bh(&hslot->lock); spin_lock(&hslot2->lock); hlist_nulls_del_init_rcu(&udp_sk(sk)->udp_portaddr_node); hslot2->count--; spin_unlock(&hslot2->lock); spin_lock(&nhslot2->lock); hlist_nulls_add_head_rcu(&udp_sk(sk)->udp_portaddr_node, &nhslot2->head); nhslot2->count++; spin_unlock(&nhslot2->lock); spin_unlock_bh(&hslot->lock); } } } EXPORT_SYMBOL(udp_lib_rehash); static void udp_v4_rehash(struct sock *sk) { u16 new_hash = udp4_portaddr_hash(sock_net(sk), inet_sk(sk)->inet_rcv_saddr, inet_sk(sk)->inet_num); udp_lib_rehash(sk, new_hash); } static int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb) { int rc; if (inet_sk(sk)->inet_daddr) { sock_rps_save_rxhash(sk, skb); sk_mark_napi_id(sk, skb); } rc = sock_queue_rcv_skb(sk, skb); if (rc < 0) { int is_udplite = IS_UDPLITE(sk); /* Note that an ENOMEM error is charged twice */ if (rc == -ENOMEM) UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_RCVBUFERRORS, is_udplite); UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_INERRORS, is_udplite); kfree_skb(skb); trace_udp_fail_queue_rcv_skb(rc, sk); return -1; } return 0; } static struct static_key udp_encap_needed __read_mostly; void udp_encap_enable(void) { if (!static_key_enabled(&udp_encap_needed)) static_key_slow_inc(&udp_encap_needed); } EXPORT_SYMBOL(udp_encap_enable); /* returns: * -1: error * 0: success * >0: "udp encap" protocol resubmission * * Note that in the success and error cases, the skb is assumed to * have either been requeued or freed. */ int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb) { struct udp_sock *up = udp_sk(sk); int rc; int is_udplite = IS_UDPLITE(sk); /* * Charge it to the socket, dropping if the queue is full. */ if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) goto drop; nf_reset(skb); if (static_key_false(&udp_encap_needed) && up->encap_type) { int (*encap_rcv)(struct sock *sk, struct sk_buff *skb); /* * This is an encapsulation socket so pass the skb to * the socket's udp_encap_rcv() hook. Otherwise, just * fall through and pass this up the UDP socket. * up->encap_rcv() returns the following value: * =0 if skb was successfully passed to the encap * handler or was discarded by it. * >0 if skb should be passed on to UDP. * <0 if skb should be resubmitted as proto -N */ /* if we're overly short, let UDP handle it */ encap_rcv = ACCESS_ONCE(up->encap_rcv); if (skb->len > sizeof(struct udphdr) && encap_rcv != NULL) { int ret; /* Verify checksum before giving to encap */ if (udp_lib_checksum_complete(skb)) goto csum_error; ret = encap_rcv(sk, skb); if (ret <= 0) { UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_INDATAGRAMS, is_udplite); return -ret; } } /* FALLTHROUGH -- it's a UDP Packet */ } /* * UDP-Lite specific tests, ignored on UDP sockets */ if ((is_udplite & UDPLITE_RECV_CC) && UDP_SKB_CB(skb)->partial_cov) { /* * MIB statistics other than incrementing the error count are * disabled for the following two types of errors: these depend * on the application settings, not on the functioning of the * protocol stack as such. * * RFC 3828 here recommends (sec 3.3): "There should also be a * way ... to ... at least let the receiving application block * delivery of packets with coverage values less than a value * provided by the application." */ if (up->pcrlen == 0) { /* full coverage was set */ LIMIT_NETDEBUG(KERN_WARNING "UDPLite: partial coverage %d while full coverage %d requested\n", UDP_SKB_CB(skb)->cscov, skb->len); goto drop; } /* The next case involves violating the min. coverage requested * by the receiver. This is subtle: if receiver wants x and x is * greater than the buffersize/MTU then receiver will complain * that it wants x while sender emits packets of smaller size y. * Therefore the above ...()->partial_cov statement is essential. */ if (UDP_SKB_CB(skb)->cscov < up->pcrlen) { LIMIT_NETDEBUG(KERN_WARNING "UDPLite: coverage %d too small, need min %d\n", UDP_SKB_CB(skb)->cscov, up->pcrlen); goto drop; } } if (rcu_access_pointer(sk->sk_filter) && udp_lib_checksum_complete(skb)) goto csum_error; if (sk_rcvqueues_full(sk, skb, sk->sk_rcvbuf)) goto drop; rc = 0; ipv4_pktinfo_prepare(sk, skb); bh_lock_sock(sk); if (!sock_owned_by_user(sk)) rc = __udp_queue_rcv_skb(sk, skb); else if (sk_add_backlog(sk, skb, sk->sk_rcvbuf)) { bh_unlock_sock(sk); goto drop; } bh_unlock_sock(sk); return rc; csum_error: UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite); drop: UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_INERRORS, is_udplite); atomic_inc(&sk->sk_drops); kfree_skb(skb); return -1; } static void flush_stack(struct sock **stack, unsigned int count, struct sk_buff *skb, unsigned int final) { unsigned int i; struct sk_buff *skb1 = NULL; struct sock *sk; for (i = 0; i < count; i++) { sk = stack[i]; if (likely(skb1 == NULL)) skb1 = (i == final) ? skb : skb_clone(skb, GFP_ATOMIC); if (!skb1) { atomic_inc(&sk->sk_drops); UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_RCVBUFERRORS, IS_UDPLITE(sk)); UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_INERRORS, IS_UDPLITE(sk)); } if (skb1 && udp_queue_rcv_skb(sk, skb1) <= 0) skb1 = NULL; } if (unlikely(skb1)) kfree_skb(skb1); } /* For TCP sockets, sk_rx_dst is protected by socket lock * For UDP, we use xchg() to guard against concurrent changes. */ static void udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst) { struct dst_entry *old; dst_hold(dst); old = xchg(&sk->sk_rx_dst, dst); dst_release(old); } /* * Multicasts and broadcasts go to each listener. * * Note: called only from the BH handler context. */ static int __udp4_lib_mcast_deliver(struct net *net, struct sk_buff *skb, struct udphdr *uh, __be32 saddr, __be32 daddr, struct udp_table *udptable) { struct sock *sk, *stack[256 / sizeof(struct sock *)]; struct udp_hslot *hslot = udp_hashslot(udptable, net, ntohs(uh->dest)); int dif; unsigned int i, count = 0; spin_lock(&hslot->lock); sk = sk_nulls_head(&hslot->head); dif = skb->dev->ifindex; sk = udp_v4_mcast_next(net, sk, uh->dest, daddr, uh->source, saddr, dif); while (sk) { stack[count++] = sk; sk = udp_v4_mcast_next(net, sk_nulls_next(sk), uh->dest, daddr, uh->source, saddr, dif); if (unlikely(count == ARRAY_SIZE(stack))) { if (!sk) break; flush_stack(stack, count, skb, ~0); count = 0; } } /* * before releasing chain lock, we must take a reference on sockets */ for (i = 0; i < count; i++) sock_hold(stack[i]); spin_unlock(&hslot->lock); /* * do the slow work with no lock held */ if (count) { flush_stack(stack, count, skb, count - 1); for (i = 0; i < count; i++) sock_put(stack[i]); } else { kfree_skb(skb); } return 0; } /* Initialize UDP checksum. If exited with zero value (success), * CHECKSUM_UNNECESSARY means, that no more checks are required. * Otherwise, csum completion requires chacksumming packet body, * including udp header and folding it to skb->csum. */ static inline int udp4_csum_init(struct sk_buff *skb, struct udphdr *uh, int proto) { int err; UDP_SKB_CB(skb)->partial_cov = 0; UDP_SKB_CB(skb)->cscov = skb->len; if (proto == IPPROTO_UDPLITE) { err = udplite_checksum_init(skb, uh); if (err) return err; } return skb_checksum_init_zero_check(skb, proto, uh->check, inet_compute_pseudo); } /* * All we need to do is get the socket, and then do a checksum. */ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable, int proto) { struct sock *sk; struct udphdr *uh; unsigned short ulen; struct rtable *rt = skb_rtable(skb); __be32 saddr, daddr; struct net *net = dev_net(skb->dev); /* * Validate the packet. */ if (!pskb_may_pull(skb, sizeof(struct udphdr))) goto drop; /* No space for header. */ uh = udp_hdr(skb); ulen = ntohs(uh->len); saddr = ip_hdr(skb)->saddr; daddr = ip_hdr(skb)->daddr; if (ulen > skb->len) goto short_packet; if (proto == IPPROTO_UDP) { /* UDP validates ulen. */ if (ulen < sizeof(*uh) || pskb_trim_rcsum(skb, ulen)) goto short_packet; uh = udp_hdr(skb); } if (udp4_csum_init(skb, uh, proto)) goto csum_error; sk = skb_steal_sock(skb); if (sk) { struct dst_entry *dst = skb_dst(skb); int ret; if (unlikely(sk->sk_rx_dst != dst)) udp_sk_rx_dst_set(sk, dst); ret = udp_queue_rcv_skb(sk, skb); sock_put(sk); /* a return value > 0 means to resubmit the input, but * it wants the return to be -protocol, or 0 */ if (ret > 0) return -ret; return 0; } else { if (rt->rt_flags & (RTCF_BROADCAST|RTCF_MULTICAST)) return __udp4_lib_mcast_deliver(net, skb, uh, saddr, daddr, udptable); sk = __udp4_lib_lookup_skb(skb, uh->source, uh->dest, udptable); } if (sk != NULL) { int ret; ret = udp_queue_rcv_skb(sk, skb); sock_put(sk); /* a return value > 0 means to resubmit the input, but * it wants the return to be -protocol, or 0 */ if (ret > 0) return -ret; return 0; } if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) goto drop; nf_reset(skb); /* No socket. Drop packet silently, if checksum is wrong */ if (udp_lib_checksum_complete(skb)) goto csum_error; UDP_INC_STATS_BH(net, UDP_MIB_NOPORTS, proto == IPPROTO_UDPLITE); icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0); /* * Hmm. We got an UDP packet to a port to which we * don't wanna listen. Ignore it. */ kfree_skb(skb); return 0; short_packet: LIMIT_NETDEBUG(KERN_DEBUG "UDP%s: short packet: From %pI4:%u %d/%d to %pI4:%u\n", proto == IPPROTO_UDPLITE ? "Lite" : "", &saddr, ntohs(uh->source), ulen, skb->len, &daddr, ntohs(uh->dest)); goto drop; csum_error: /* * RFC1122: OK. Discards the bad packet silently (as far as * the network is concerned, anyway) as per 4.1.3.4 (MUST). */ LIMIT_NETDEBUG(KERN_DEBUG "UDP%s: bad checksum. From %pI4:%u to %pI4:%u ulen %d\n", proto == IPPROTO_UDPLITE ? "Lite" : "", &saddr, ntohs(uh->source), &daddr, ntohs(uh->dest), ulen); UDP_INC_STATS_BH(net, UDP_MIB_CSUMERRORS, proto == IPPROTO_UDPLITE); drop: UDP_INC_STATS_BH(net, UDP_MIB_INERRORS, proto == IPPROTO_UDPLITE); kfree_skb(skb); return 0; } /* We can only early demux multicast if there is a single matching socket. * If more than one socket found returns NULL */ static struct sock *__udp4_lib_mcast_demux_lookup(struct net *net, __be16 loc_port, __be32 loc_addr, __be16 rmt_port, __be32 rmt_addr, int dif) { struct sock *sk, *result; struct hlist_nulls_node *node; unsigned short hnum = ntohs(loc_port); unsigned int count, slot = udp_hashfn(net, hnum, udp_table.mask); struct udp_hslot *hslot = &udp_table.hash[slot]; rcu_read_lock(); begin: count = 0; result = NULL; sk_nulls_for_each_rcu(sk, node, &hslot->head) { if (__udp_is_mcast_sock(net, sk, loc_port, loc_addr, rmt_port, rmt_addr, dif, hnum)) { result = sk; ++count; } } /* * if the nulls value we got at the end of this lookup is * not the expected one, we must restart lookup. * We probably met an item that was moved to another chain. */ if (get_nulls_value(node) != slot) goto begin; if (result) { if (count != 1 || unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2))) result = NULL; else if (unlikely(!__udp_is_mcast_sock(net, result, loc_port, loc_addr, rmt_port, rmt_addr, dif, hnum))) { sock_put(result); result = NULL; } } rcu_read_unlock(); return result; } /* For unicast we should only early demux connected sockets or we can * break forwarding setups. The chains here can be long so only check * if the first socket is an exact match and if not move on. */ static struct sock *__udp4_lib_demux_lookup(struct net *net, __be16 loc_port, __be32 loc_addr, __be16 rmt_port, __be32 rmt_addr, int dif) { struct sock *sk, *result; struct hlist_nulls_node *node; unsigned short hnum = ntohs(loc_port); unsigned int hash2 = udp4_portaddr_hash(net, loc_addr, hnum); unsigned int slot2 = hash2 & udp_table.mask; struct udp_hslot *hslot2 = &udp_table.hash2[slot2]; INET_ADDR_COOKIE(acookie, rmt_addr, loc_addr); const __portpair ports = INET_COMBINED_PORTS(rmt_port, hnum); rcu_read_lock(); result = NULL; udp_portaddr_for_each_entry_rcu(sk, node, &hslot2->head) { if (INET_MATCH(sk, net, acookie, rmt_addr, loc_addr, ports, dif)) result = sk; /* Only check first socket in chain */ break; } if (result) { if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2))) result = NULL; else if (unlikely(!INET_MATCH(sk, net, acookie, rmt_addr, loc_addr, ports, dif))) { sock_put(result); result = NULL; } } rcu_read_unlock(); return result; } void udp_v4_early_demux(struct sk_buff *skb) { struct net *net = dev_net(skb->dev); const struct iphdr *iph; const struct udphdr *uh; struct sock *sk; struct dst_entry *dst; int dif = skb->dev->ifindex; /* validate the packet */ if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct udphdr))) return; iph = ip_hdr(skb); uh = udp_hdr(skb); if (skb->pkt_type == PACKET_BROADCAST || skb->pkt_type == PACKET_MULTICAST) sk = __udp4_lib_mcast_demux_lookup(net, uh->dest, iph->daddr, uh->source, iph->saddr, dif); else if (skb->pkt_type == PACKET_HOST) sk = __udp4_lib_demux_lookup(net, uh->dest, iph->daddr, uh->source, iph->saddr, dif); else return; if (!sk) return; skb->sk = sk; skb->destructor = sock_edemux; dst = sk->sk_rx_dst; if (dst) dst = dst_check(dst, 0); if (dst) skb_dst_set_noref(skb, dst); } int udp_rcv(struct sk_buff *skb) { return __udp4_lib_rcv(skb, &udp_table, IPPROTO_UDP); } void udp_destroy_sock(struct sock *sk) { struct udp_sock *up = udp_sk(sk); bool slow = lock_sock_fast(sk); udp_flush_pending_frames(sk); unlock_sock_fast(sk, slow); if (static_key_false(&udp_encap_needed) && up->encap_type) { void (*encap_destroy)(struct sock *sk); encap_destroy = ACCESS_ONCE(up->encap_destroy); if (encap_destroy) encap_destroy(sk); } } /* * Socket option code for UDP */ int udp_lib_setsockopt(struct sock *sk, int level, int optname, char __user *optval, unsigned int optlen, int (*push_pending_frames)(struct sock *)) { struct udp_sock *up = udp_sk(sk); int val, valbool; int err = 0; int is_udplite = IS_UDPLITE(sk); if (optlen < sizeof(int)) return -EINVAL; if (get_user(val, (int __user *)optval)) return -EFAULT; valbool = val ? 1 : 0; switch (optname) { case UDP_CORK: if (val != 0) { up->corkflag = 1; } else { up->corkflag = 0; lock_sock(sk); (*push_pending_frames)(sk); release_sock(sk); } break; case UDP_ENCAP: switch (val) { case 0: case UDP_ENCAP_ESPINUDP: case UDP_ENCAP_ESPINUDP_NON_IKE: up->encap_rcv = xfrm4_udp_encap_rcv; /* FALLTHROUGH */ case UDP_ENCAP_L2TPINUDP: up->encap_type = val; udp_encap_enable(); break; default: err = -ENOPROTOOPT; break; } break; case UDP_NO_CHECK6_TX: up->no_check6_tx = valbool; break; case UDP_NO_CHECK6_RX: up->no_check6_rx = valbool; break; /* * UDP-Lite's partial checksum coverage (RFC 3828). */ /* The sender sets actual checksum coverage length via this option. * The case coverage > packet length is handled by send module. */ case UDPLITE_SEND_CSCOV: if (!is_udplite) /* Disable the option on UDP sockets */ return -ENOPROTOOPT; if (val != 0 && val < 8) /* Illegal coverage: use default (8) */ val = 8; else if (val > USHRT_MAX) val = USHRT_MAX; up->pcslen = val; up->pcflag |= UDPLITE_SEND_CC; break; /* The receiver specifies a minimum checksum coverage value. To make * sense, this should be set to at least 8 (as done below). If zero is * used, this again means full checksum coverage. */ case UDPLITE_RECV_CSCOV: if (!is_udplite) /* Disable the option on UDP sockets */ return -ENOPROTOOPT; if (val != 0 && val < 8) /* Avoid silly minimal values. */ val = 8; else if (val > USHRT_MAX) val = USHRT_MAX; up->pcrlen = val; up->pcflag |= UDPLITE_RECV_CC; break; default: err = -ENOPROTOOPT; break; } return err; } EXPORT_SYMBOL(udp_lib_setsockopt); int udp_setsockopt(struct sock *sk, int level, int optname, char __user *optval, unsigned int optlen) { if (level == SOL_UDP || level == SOL_UDPLITE) return udp_lib_setsockopt(sk, level, optname, optval, optlen, udp_push_pending_frames); return ip_setsockopt(sk, level, optname, optval, optlen); } #ifdef CONFIG_COMPAT int compat_udp_setsockopt(struct sock *sk, int level, int optname, char __user *optval, unsigned int optlen) { if (level == SOL_UDP || level == SOL_UDPLITE) return udp_lib_setsockopt(sk, level, optname, optval, optlen, udp_push_pending_frames); return compat_ip_setsockopt(sk, level, optname, optval, optlen); } #endif int udp_lib_getsockopt(struct sock *sk, int level, int optname, char __user *optval, int __user *optlen) { struct udp_sock *up = udp_sk(sk); int val, len; if (get_user(len, optlen)) return -EFAULT; len = min_t(unsigned int, len, sizeof(int)); if (len < 0) return -EINVAL; switch (optname) { case UDP_CORK: val = up->corkflag; break; case UDP_ENCAP: val = up->encap_type; break; case UDP_NO_CHECK6_TX: val = up->no_check6_tx; break; case UDP_NO_CHECK6_RX: val = up->no_check6_rx; break; /* The following two cannot be changed on UDP sockets, the return is * always 0 (which corresponds to the full checksum coverage of UDP). */ case UDPLITE_SEND_CSCOV: val = up->pcslen; break; case UDPLITE_RECV_CSCOV: val = up->pcrlen; break; default: return -ENOPROTOOPT; } if (put_user(len, optlen)) return -EFAULT; if (copy_to_user(optval, &val, len)) return -EFAULT; return 0; } EXPORT_SYMBOL(udp_lib_getsockopt); int udp_getsockopt(struct sock *sk, int level, int optname, char __user *optval, int __user *optlen) { if (level == SOL_UDP || level == SOL_UDPLITE) return udp_lib_getsockopt(sk, level, optname, optval, optlen); return ip_getsockopt(sk, level, optname, optval, optlen); } #ifdef CONFIG_COMPAT int compat_udp_getsockopt(struct sock *sk, int level, int optname, char __user *optval, int __user *optlen) { if (level == SOL_UDP || level == SOL_UDPLITE) return udp_lib_getsockopt(sk, level, optname, optval, optlen); return compat_ip_getsockopt(sk, level, optname, optval, optlen); } #endif /** * udp_poll - wait for a UDP event. * @file - file struct * @sock - socket * @wait - poll table * * This is same as datagram poll, except for the special case of * blocking sockets. If application is using a blocking fd * and a packet with checksum error is in the queue; * then it could get return from select indicating data available * but then block when reading it. Add special case code * to work around these arguably broken applications. */ unsigned int udp_poll(struct file *file, struct socket *sock, poll_table *wait) { unsigned int mask = datagram_poll(file, sock, wait); struct sock *sk = sock->sk; sock_rps_record_flow(sk); /* Check for false positives due to checksum errors */ if ((mask & POLLRDNORM) && !(file->f_flags & O_NONBLOCK) && !(sk->sk_shutdown & RCV_SHUTDOWN) && !first_packet_length(sk)) mask &= ~(POLLIN | POLLRDNORM); return mask; } EXPORT_SYMBOL(udp_poll); struct proto udp_prot = { .name = "UDP", .owner = THIS_MODULE, .close = udp_lib_close, .connect = ip4_datagram_connect, .disconnect = udp_disconnect, .ioctl = udp_ioctl, .destroy = udp_destroy_sock, .setsockopt = udp_setsockopt, .getsockopt = udp_getsockopt, .sendmsg = udp_sendmsg, .recvmsg = udp_recvmsg, .sendpage = udp_sendpage, .backlog_rcv = __udp_queue_rcv_skb, .release_cb = ip4_datagram_release_cb, .hash = udp_lib_hash, .unhash = udp_lib_unhash, .rehash = udp_v4_rehash, .get_port = udp_v4_get_port, .memory_allocated = &udp_memory_allocated, .sysctl_mem = sysctl_udp_mem, .sysctl_wmem = &sysctl_udp_wmem_min, .sysctl_rmem = &sysctl_udp_rmem_min, .obj_size = sizeof(struct udp_sock), .slab_flags = SLAB_DESTROY_BY_RCU, .h.udp_table = &udp_table, #ifdef CONFIG_COMPAT .compat_setsockopt = compat_udp_setsockopt, .compat_getsockopt = compat_udp_getsockopt, #endif .clear_sk = sk_prot_clear_portaddr_nulls, }; EXPORT_SYMBOL(udp_prot); /* ------------------------------------------------------------------------ */ #ifdef CONFIG_PROC_FS static struct sock *udp_get_first(struct seq_file *seq, int start) { struct sock *sk; struct udp_iter_state *state = seq->private; struct net *net = seq_file_net(seq); for (state->bucket = start; state->bucket <= state->udp_table->mask; ++state->bucket) { struct hlist_nulls_node *node; struct udp_hslot *hslot = &state->udp_table->hash[state->bucket]; if (hlist_nulls_empty(&hslot->head)) continue; spin_lock_bh(&hslot->lock); sk_nulls_for_each(sk, node, &hslot->head) { if (!net_eq(sock_net(sk), net)) continue; if (sk->sk_family == state->family) goto found; } spin_unlock_bh(&hslot->lock); } sk = NULL; found: return sk; } static struct sock *udp_get_next(struct seq_file *seq, struct sock *sk) { struct udp_iter_state *state = seq->private; struct net *net = seq_file_net(seq); do { sk = sk_nulls_next(sk); } while (sk && (!net_eq(sock_net(sk), net) || sk->sk_family != state->family)); if (!sk) { if (state->bucket <= state->udp_table->mask) spin_unlock_bh(&state->udp_table->hash[state->bucket].lock); return udp_get_first(seq, state->bucket + 1); } return sk; } static struct sock *udp_get_idx(struct seq_file *seq, loff_t pos) { struct sock *sk = udp_get_first(seq, 0); if (sk) while (pos && (sk = udp_get_next(seq, sk)) != NULL) --pos; return pos ? NULL : sk; } static void *udp_seq_start(struct seq_file *seq, loff_t *pos) { struct udp_iter_state *state = seq->private; state->bucket = MAX_UDP_PORTS; return *pos ? udp_get_idx(seq, *pos-1) : SEQ_START_TOKEN; } static void *udp_seq_next(struct seq_file *seq, void *v, loff_t *pos) { struct sock *sk; if (v == SEQ_START_TOKEN) sk = udp_get_idx(seq, 0); else sk = udp_get_next(seq, v); ++*pos; return sk; } static void udp_seq_stop(struct seq_file *seq, void *v) { struct udp_iter_state *state = seq->private; if (state->bucket <= state->udp_table->mask) spin_unlock_bh(&state->udp_table->hash[state->bucket].lock); } int udp_seq_open(struct inode *inode, struct file *file) { struct udp_seq_afinfo *afinfo = PDE_DATA(inode); struct udp_iter_state *s; int err; err = seq_open_net(inode, file, &afinfo->seq_ops, sizeof(struct udp_iter_state)); if (err < 0) return err; s = ((struct seq_file *)file->private_data)->private; s->family = afinfo->family; s->udp_table = afinfo->udp_table; return err; } EXPORT_SYMBOL(udp_seq_open); /* ------------------------------------------------------------------------ */ int udp_proc_register(struct net *net, struct udp_seq_afinfo *afinfo) { struct proc_dir_entry *p; int rc = 0; afinfo->seq_ops.start = udp_seq_start; afinfo->seq_ops.next = udp_seq_next; afinfo->seq_ops.stop = udp_seq_stop; p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net, afinfo->seq_fops, afinfo); if (!p) rc = -ENOMEM; return rc; } EXPORT_SYMBOL(udp_proc_register); void udp_proc_unregister(struct net *net, struct udp_seq_afinfo *afinfo) { remove_proc_entry(afinfo->name, net->proc_net); } EXPORT_SYMBOL(udp_proc_unregister); /* ------------------------------------------------------------------------ */ static void udp4_format_sock(struct sock *sp, struct seq_file *f, int bucket) { struct inet_sock *inet = inet_sk(sp); __be32 dest = inet->inet_daddr; __be32 src = inet->inet_rcv_saddr; __u16 destp = ntohs(inet->inet_dport); __u16 srcp = ntohs(inet->inet_sport); seq_printf(f, "%5d: %08X:%04X %08X:%04X" " %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d", bucket, src, srcp, dest, destp, sp->sk_state, sk_wmem_alloc_get(sp), sk_rmem_alloc_get(sp), 0, 0L, 0, from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)), 0, sock_i_ino(sp), atomic_read(&sp->sk_refcnt), sp, atomic_read(&sp->sk_drops)); } int udp4_seq_show(struct seq_file *seq, void *v) { seq_setwidth(seq, 127); if (v == SEQ_START_TOKEN) seq_puts(seq, " sl local_address rem_address st tx_queue " "rx_queue tr tm->when retrnsmt uid timeout " "inode ref pointer drops"); else { struct udp_iter_state *state = seq->private; udp4_format_sock(v, seq, state->bucket); } seq_pad(seq, '\n'); return 0; } static const struct file_operations udp_afinfo_seq_fops = { .owner = THIS_MODULE, .open = udp_seq_open, .read = seq_read, .llseek = seq_lseek, .release = seq_release_net }; /* ------------------------------------------------------------------------ */ static struct udp_seq_afinfo udp4_seq_afinfo = { .name = "udp", .family = AF_INET, .udp_table = &udp_table, .seq_fops = &udp_afinfo_seq_fops, .seq_ops = { .show = udp4_seq_show, }, }; static int __net_init udp4_proc_init_net(struct net *net) { return udp_proc_register(net, &udp4_seq_afinfo); } static void __net_exit udp4_proc_exit_net(struct net *net) { udp_proc_unregister(net, &udp4_seq_afinfo); } static struct pernet_operations udp4_net_ops = { .init = udp4_proc_init_net, .exit = udp4_proc_exit_net, }; int __init udp4_proc_init(void) { return register_pernet_subsys(&udp4_net_ops); } void udp4_proc_exit(void) { unregister_pernet_subsys(&udp4_net_ops); } #endif /* CONFIG_PROC_FS */ static __initdata unsigned long uhash_entries; static int __init set_uhash_entries(char *str) { ssize_t ret; if (!str) return 0; ret = kstrtoul(str, 0, &uhash_entries); if (ret) return 0; if (uhash_entries && uhash_entries < UDP_HTABLE_SIZE_MIN) uhash_entries = UDP_HTABLE_SIZE_MIN; return 1; } __setup("uhash_entries=", set_uhash_entries); void __init udp_table_init(struct udp_table *table, const char *name) { unsigned int i; table->hash = alloc_large_system_hash(name, 2 * sizeof(struct udp_hslot), uhash_entries, 21, /* one slot per 2 MB */ 0, &table->log, &table->mask, UDP_HTABLE_SIZE_MIN, 64 * 1024); table->hash2 = table->hash + (table->mask + 1); for (i = 0; i <= table->mask; i++) { INIT_HLIST_NULLS_HEAD(&table->hash[i].head, i); table->hash[i].count = 0; spin_lock_init(&table->hash[i].lock); } for (i = 0; i <= table->mask; i++) { INIT_HLIST_NULLS_HEAD(&table->hash2[i].head, i); table->hash2[i].count = 0; spin_lock_init(&table->hash2[i].lock); } } void __init udp_init(void) { unsigned long limit; udp_table_init(&udp_table, "UDP"); limit = nr_free_buffer_pages() / 8; limit = max(limit, 128UL); sysctl_udp_mem[0] = limit / 4 * 3; sysctl_udp_mem[1] = limit; sysctl_udp_mem[2] = sysctl_udp_mem[0] * 2; sysctl_udp_rmem_min = SK_MEM_QUANTUM; sysctl_udp_wmem_min = SK_MEM_QUANTUM; } struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb, netdev_features_t features) { struct sk_buff *segs = ERR_PTR(-EINVAL); u16 mac_offset = skb->mac_header; int mac_len = skb->mac_len; int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb); __be16 protocol = skb->protocol; netdev_features_t enc_features; int udp_offset, outer_hlen; unsigned int oldlen; bool need_csum; oldlen = (u16)~skb->len; if (unlikely(!pskb_may_pull(skb, tnl_hlen))) goto out; skb->encapsulation = 0; __skb_pull(skb, tnl_hlen); skb_reset_mac_header(skb); skb_set_network_header(skb, skb_inner_network_offset(skb)); skb->mac_len = skb_inner_network_offset(skb); skb->protocol = htons(ETH_P_TEB); need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM); if (need_csum) skb->encap_hdr_csum = 1; /* segment inner packet. */ enc_features = skb->dev->hw_enc_features & netif_skb_features(skb); segs = skb_mac_gso_segment(skb, enc_features); if (!segs || IS_ERR(segs)) { skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset, mac_len); goto out; } outer_hlen = skb_tnl_header_len(skb); udp_offset = outer_hlen - tnl_hlen; skb = segs; do { struct udphdr *uh; int len; skb_reset_inner_headers(skb); skb->encapsulation = 1; skb->mac_len = mac_len; skb_push(skb, outer_hlen); skb_reset_mac_header(skb); skb_set_network_header(skb, mac_len); skb_set_transport_header(skb, udp_offset); len = skb->len - udp_offset; uh = udp_hdr(skb); uh->len = htons(len); if (need_csum) { __be32 delta = htonl(oldlen + len); uh->check = ~csum_fold((__force __wsum) ((__force u32)uh->check + (__force u32)delta)); uh->check = gso_make_checksum(skb, ~uh->check); if (uh->check == 0) uh->check = CSUM_MANGLED_0; } skb->protocol = protocol; } while ((skb = skb->next)); out: return segs; }