/* * net/dccp/ipv4.c * * An implementation of the DCCP protocol * Arnaldo Carvalho de Melo * * 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. */ #include #include #include #include #include #include #include #include #include #include #include #include "ccid.h" #include "dccp.h" struct inet_hashinfo __cacheline_aligned dccp_hashinfo = { .lhash_lock = RW_LOCK_UNLOCKED, .lhash_users = ATOMIC_INIT(0), .lhash_wait = __WAIT_QUEUE_HEAD_INITIALIZER(dccp_hashinfo.lhash_wait), .portalloc_lock = SPIN_LOCK_UNLOCKED, .port_rover = 1024 - 1, }; EXPORT_SYMBOL_GPL(dccp_hashinfo); static int dccp_v4_get_port(struct sock *sk, const unsigned short snum) { return inet_csk_get_port(&dccp_hashinfo, sk, snum); } static void dccp_v4_hash(struct sock *sk) { inet_hash(&dccp_hashinfo, sk); } static void dccp_v4_unhash(struct sock *sk) { inet_unhash(&dccp_hashinfo, sk); } /* called with local bh disabled */ static int __dccp_v4_check_established(struct sock *sk, const __u16 lport, struct inet_timewait_sock **twp) { struct inet_sock *inet = inet_sk(sk); const u32 daddr = inet->rcv_saddr; const u32 saddr = inet->daddr; const int dif = sk->sk_bound_dev_if; INET_ADDR_COOKIE(acookie, saddr, daddr) const __u32 ports = INET_COMBINED_PORTS(inet->dport, lport); const int hash = inet_ehashfn(daddr, lport, saddr, inet->dport, dccp_hashinfo.ehash_size); struct inet_ehash_bucket *head = &dccp_hashinfo.ehash[hash]; const struct sock *sk2; const struct hlist_node *node; struct inet_timewait_sock *tw; write_lock(&head->lock); /* Check TIME-WAIT sockets first. */ sk_for_each(sk2, node, &(head + dccp_hashinfo.ehash_size)->chain) { tw = inet_twsk(sk2); if (INET_TW_MATCH(sk2, acookie, saddr, daddr, ports, dif)) goto not_unique; } tw = NULL; /* And established part... */ sk_for_each(sk2, node, &head->chain) { if (INET_MATCH(sk2, acookie, saddr, daddr, ports, dif)) goto not_unique; } /* Must record num and sport now. Otherwise we will see * in hash table socket with a funny identity. */ inet->num = lport; inet->sport = htons(lport); sk->sk_hashent = hash; BUG_TRAP(sk_unhashed(sk)); __sk_add_node(sk, &head->chain); sock_prot_inc_use(sk->sk_prot); write_unlock(&head->lock); if (twp != NULL) { *twp = tw; NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED); } else if (tw != NULL) { /* Silly. Should hash-dance instead... */ inet_twsk_deschedule(tw, &dccp_death_row); NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED); inet_twsk_put(tw); } return 0; not_unique: write_unlock(&head->lock); return -EADDRNOTAVAIL; } /* * Bind a port for a connect operation and hash it. */ static int dccp_v4_hash_connect(struct sock *sk) { const unsigned short snum = inet_sk(sk)->num; struct inet_bind_hashbucket *head; struct inet_bind_bucket *tb; int ret; if (snum == 0) { int rover; int low = sysctl_local_port_range[0]; int high = sysctl_local_port_range[1]; int remaining = (high - low) + 1; struct hlist_node *node; struct inet_timewait_sock *tw = NULL; local_bh_disable(); /* TODO. Actually it is not so bad idea to remove * dccp_hashinfo.portalloc_lock before next submission to Linus. * As soon as we touch this place at all it is time to think. * * Now it protects single _advisory_ variable dccp_hashinfo.port_rover, * hence it is mostly useless. * Code will work nicely if we just delete it, but * I am afraid in contented case it will work not better or * even worse: another cpu just will hit the same bucket * and spin there. * So some cpu salt could remove both contention and * memory pingpong. Any ideas how to do this in a nice way? */ spin_lock(&dccp_hashinfo.portalloc_lock); rover = dccp_hashinfo.port_rover; do { rover++; if ((rover < low) || (rover > high)) rover = low; head = &dccp_hashinfo.bhash[inet_bhashfn(rover, dccp_hashinfo.bhash_size)]; spin_lock(&head->lock); /* Does not bother with rcv_saddr checks, * because the established check is already * unique enough. */ inet_bind_bucket_for_each(tb, node, &head->chain) { if (tb->port == rover) { BUG_TRAP(!hlist_empty(&tb->owners)); if (tb->fastreuse >= 0) goto next_port; if (!__dccp_v4_check_established(sk, rover, &tw)) goto ok; goto next_port; } } tb = inet_bind_bucket_create(dccp_hashinfo.bind_bucket_cachep, head, rover); if (tb == NULL) { spin_unlock(&head->lock); break; } tb->fastreuse = -1; goto ok; next_port: spin_unlock(&head->lock); } while (--remaining > 0); dccp_hashinfo.port_rover = rover; spin_unlock(&dccp_hashinfo.portalloc_lock); local_bh_enable(); return -EADDRNOTAVAIL; ok: /* All locks still held and bhs disabled */ dccp_hashinfo.port_rover = rover; spin_unlock(&dccp_hashinfo.portalloc_lock); inet_bind_hash(sk, tb, rover); if (sk_unhashed(sk)) { inet_sk(sk)->sport = htons(rover); __inet_hash(&dccp_hashinfo, sk, 0); } spin_unlock(&head->lock); if (tw != NULL) { inet_twsk_deschedule(tw, &dccp_death_row); inet_twsk_put(tw); } ret = 0; goto out; } head = &dccp_hashinfo.bhash[inet_bhashfn(snum, dccp_hashinfo.bhash_size)]; tb = inet_csk(sk)->icsk_bind_hash; spin_lock_bh(&head->lock); if (sk_head(&tb->owners) == sk && sk->sk_bind_node.next == NULL) { __inet_hash(&dccp_hashinfo, sk, 0); spin_unlock_bh(&head->lock); return 0; } else { spin_unlock(&head->lock); /* No definite answer... Walk to established hash table */ ret = __dccp_v4_check_established(sk, snum, NULL); out: local_bh_enable(); return ret; } } static int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) { struct inet_sock *inet = inet_sk(sk); struct dccp_sock *dp = dccp_sk(sk); const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr; struct rtable *rt; u32 daddr, nexthop; int tmp; int err; dp->dccps_role = DCCP_ROLE_CLIENT; if (addr_len < sizeof(struct sockaddr_in)) return -EINVAL; if (usin->sin_family != AF_INET) return -EAFNOSUPPORT; nexthop = daddr = usin->sin_addr.s_addr; if (inet->opt != NULL && inet->opt->srr) { if (daddr == 0) return -EINVAL; nexthop = inet->opt->faddr; } tmp = ip_route_connect(&rt, nexthop, inet->saddr, RT_CONN_FLAGS(sk), sk->sk_bound_dev_if, IPPROTO_DCCP, inet->sport, usin->sin_port, sk); if (tmp < 0) return tmp; if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { ip_rt_put(rt); return -ENETUNREACH; } if (inet->opt == NULL || !inet->opt->srr) daddr = rt->rt_dst; if (inet->saddr == 0) inet->saddr = rt->rt_src; inet->rcv_saddr = inet->saddr; inet->dport = usin->sin_port; inet->daddr = daddr; dp->dccps_ext_header_len = 0; if (inet->opt != NULL) dp->dccps_ext_header_len = inet->opt->optlen; /* * Socket identity is still unknown (sport may be zero). * However we set state to DCCP_REQUESTING and not releasing socket * lock select source port, enter ourselves into the hash tables and * complete initialization after this. */ dccp_set_state(sk, DCCP_REQUESTING); err = dccp_v4_hash_connect(sk); if (err != 0) goto failure; err = ip_route_newports(&rt, inet->sport, inet->dport, sk); if (err != 0) goto failure; /* OK, now commit destination to socket. */ sk_setup_caps(sk, &rt->u.dst); dp->dccps_gar = dp->dccps_iss = secure_dccp_sequence_number(inet->saddr, inet->daddr, inet->sport, usin->sin_port); dccp_update_gss(sk, dp->dccps_iss); inet->id = dp->dccps_iss ^ jiffies; err = dccp_connect(sk); rt = NULL; if (err != 0) goto failure; out: return err; failure: /* This unhashes the socket and releases the local port, if necessary. */ dccp_set_state(sk, DCCP_CLOSED); ip_rt_put(rt); sk->sk_route_caps = 0; inet->dport = 0; goto out; } /* * This routine does path mtu discovery as defined in RFC1191. */ static inline void dccp_do_pmtu_discovery(struct sock *sk, const struct iphdr *iph, u32 mtu) { struct dst_entry *dst; const struct inet_sock *inet = inet_sk(sk); const struct dccp_sock *dp = dccp_sk(sk); /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs * send out by Linux are always < 576bytes so they should go through * unfragmented). */ if (sk->sk_state == DCCP_LISTEN) return; /* We don't check in the destentry if pmtu discovery is forbidden * on this route. We just assume that no packet_to_big packets * are send back when pmtu discovery is not active. * There is a small race when the user changes this flag in the * route, but I think that's acceptable. */ if ((dst = __sk_dst_check(sk, 0)) == NULL) return; dst->ops->update_pmtu(dst, mtu); /* Something is about to be wrong... Remember soft error * for the case, if this connection will not able to recover. */ if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) sk->sk_err_soft = EMSGSIZE; mtu = dst_mtu(dst); if (inet->pmtudisc != IP_PMTUDISC_DONT && dp->dccps_pmtu_cookie > mtu) { dccp_sync_mss(sk, mtu); /* * From: draft-ietf-dccp-spec-11.txt * * DCCP-Sync packets are the best choice for upward probing, * since DCCP-Sync probes do not risk application data loss. */ dccp_send_sync(sk, dp->dccps_gsr); } /* else let the usual retransmit timer handle it */ } static void dccp_v4_ctl_send_ack(struct sk_buff *rxskb) { int err; struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh; const int dccp_hdr_ack_len = sizeof(struct dccp_hdr) + sizeof(struct dccp_hdr_ext) + sizeof(struct dccp_hdr_ack_bits); struct sk_buff *skb; if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL) return; skb = alloc_skb(MAX_DCCP_HEADER + 15, GFP_ATOMIC); if (skb == NULL) return; /* Reserve space for headers. */ skb_reserve(skb, MAX_DCCP_HEADER); skb->dst = dst_clone(rxskb->dst); skb->h.raw = skb_push(skb, dccp_hdr_ack_len); dh = dccp_hdr(skb); memset(dh, 0, dccp_hdr_ack_len); /* Build DCCP header and checksum it. */ dh->dccph_type = DCCP_PKT_ACK; dh->dccph_sport = rxdh->dccph_dport; dh->dccph_dport = rxdh->dccph_sport; dh->dccph_doff = dccp_hdr_ack_len / 4; dh->dccph_x = 1; dccp_hdr_set_seq(dh, DCCP_SKB_CB(rxskb)->dccpd_ack_seq); dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), DCCP_SKB_CB(rxskb)->dccpd_seq); bh_lock_sock(dccp_ctl_socket->sk); err = ip_build_and_send_pkt(skb, dccp_ctl_socket->sk, rxskb->nh.iph->daddr, rxskb->nh.iph->saddr, NULL); bh_unlock_sock(dccp_ctl_socket->sk); if (err == NET_XMIT_CN || err == 0) { DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS); DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS); } } static void dccp_v4_reqsk_send_ack(struct sk_buff *skb, struct request_sock *req) { dccp_v4_ctl_send_ack(skb); } static int dccp_v4_send_response(struct sock *sk, struct request_sock *req, struct dst_entry *dst) { int err = -1; struct sk_buff *skb; /* First, grab a route. */ if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL) goto out; skb = dccp_make_response(sk, dst, req); if (skb != NULL) { const struct inet_request_sock *ireq = inet_rsk(req); err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr, ireq->rmt_addr, ireq->opt); if (err == NET_XMIT_CN) err = 0; } out: dst_release(dst); return err; } /* * 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. * After adjustment header points to the first 8 bytes of the tcp header. We * need to find the appropriate port. * * The locking strategy used here is very "optimistic". When someone else * accesses the socket the ICMP is just dropped and for some paths there is no * check at all. A more general error queue to queue errors for later handling * is probably better. */ void dccp_v4_err(struct sk_buff *skb, u32 info) { const struct iphdr *iph = (struct iphdr *)skb->data; const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + (iph->ihl << 2)); struct dccp_sock *dp; struct inet_sock *inet; const int type = skb->h.icmph->type; const int code = skb->h.icmph->code; struct sock *sk; __u64 seq; int err; if (skb->len < (iph->ihl << 2) + 8) { ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); return; } sk = inet_lookup(&dccp_hashinfo, iph->daddr, dh->dccph_dport, iph->saddr, dh->dccph_sport, inet_iif(skb)); if (sk == NULL) { ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); return; } if (sk->sk_state == DCCP_TIME_WAIT) { inet_twsk_put((struct inet_timewait_sock *)sk); return; } bh_lock_sock(sk); /* If too many ICMPs get dropped on busy * servers this needs to be solved differently. */ if (sock_owned_by_user(sk)) NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS); if (sk->sk_state == DCCP_CLOSED) goto out; dp = dccp_sk(sk); seq = dccp_hdr_seq(skb); if (sk->sk_state != DCCP_LISTEN && !between48(seq, dp->dccps_swl, dp->dccps_swh)) { NET_INC_STATS(LINUX_MIB_OUTOFWINDOWICMPS); goto out; } switch (type) { case ICMP_SOURCE_QUENCH: /* Just silently ignore these. */ goto out; case ICMP_PARAMETERPROB: err = EPROTO; break; case ICMP_DEST_UNREACH: if (code > NR_ICMP_UNREACH) goto out; if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ if (!sock_owned_by_user(sk)) dccp_do_pmtu_discovery(sk, iph, info); goto out; } err = icmp_err_convert[code].errno; break; case ICMP_TIME_EXCEEDED: err = EHOSTUNREACH; break; default: goto out; } switch (sk->sk_state) { struct request_sock *req , **prev; case DCCP_LISTEN: if (sock_owned_by_user(sk)) goto out; req = inet_csk_search_req(sk, &prev, dh->dccph_dport, iph->daddr, iph->saddr); if (!req) goto out; /* * ICMPs are not backlogged, hence we cannot get an established * socket here. */ BUG_TRAP(!req->sk); if (seq != dccp_rsk(req)->dreq_iss) { NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS); goto out; } /* * Still in RESPOND, just remove it silently. * There is no good way to pass the error to the newly * created socket, and POSIX does not want network * errors returned from accept(). */ inet_csk_reqsk_queue_drop(sk, req, prev); goto out; case DCCP_REQUESTING: case DCCP_RESPOND: if (!sock_owned_by_user(sk)) { DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS); sk->sk_err = err; sk->sk_error_report(sk); dccp_done(sk); } else sk->sk_err_soft = err; goto out; } /* If we've already connected we will keep trying * until we time out, or the user gives up. * * rfc1122 4.2.3.9 allows to consider as hard errors * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, * but it is obsoleted by pmtu discovery). * * Note, that in modern internet, where routing is unreliable * and in each dark corner broken firewalls sit, sending random * errors ordered by their masters even this two messages finally lose * their original sense (even Linux sends invalid PORT_UNREACHs) * * Now we are in compliance with RFCs. * --ANK (980905) */ inet = inet_sk(sk); if (!sock_owned_by_user(sk) && inet->recverr) { sk->sk_err = err; sk->sk_error_report(sk); } else /* Only an error on timeout */ sk->sk_err_soft = err; out: bh_unlock_sock(sk); sock_put(sk); } extern struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst, enum dccp_reset_codes code); int dccp_v4_send_reset(struct sock *sk, enum dccp_reset_codes code) { struct sk_buff *skb; /* * FIXME: what if rebuild_header fails? * Should we be doing a rebuild_header here? */ int err = inet_sk_rebuild_header(sk); if (err != 0) return err; skb = dccp_make_reset(sk, sk->sk_dst_cache, code); if (skb != NULL) { const struct dccp_sock *dp = dccp_sk(sk); const struct inet_sock *inet = inet_sk(sk); err = ip_build_and_send_pkt(skb, sk, inet->saddr, inet->daddr, NULL); if (err == NET_XMIT_CN) err = 0; ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk); ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk); } return err; } static inline u64 dccp_v4_init_sequence(const struct sock *sk, const struct sk_buff *skb) { return secure_dccp_sequence_number(skb->nh.iph->daddr, skb->nh.iph->saddr, dccp_hdr(skb)->dccph_dport, dccp_hdr(skb)->dccph_sport); } int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) { struct inet_request_sock *ireq; struct dccp_sock dp; struct request_sock *req; struct dccp_request_sock *dreq; const __u32 saddr = skb->nh.iph->saddr; const __u32 daddr = skb->nh.iph->daddr; struct dst_entry *dst = NULL; /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ if (((struct rtable *)skb->dst)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) goto drop; /* * TW buckets are converted to open requests without * limitations, they conserve resources and peer is * evidently real one. */ if (inet_csk_reqsk_queue_is_full(sk)) goto drop; /* * Accept backlog is full. If we have already queued enough * of warm entries in syn queue, drop request. It is better than * clogging syn queue with openreqs with exponentially increasing * timeout. */ if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) goto drop; req = reqsk_alloc(sk->sk_prot->rsk_prot); if (req == NULL) goto drop; /* FIXME: process options */ dccp_openreq_init(req, &dp, skb); ireq = inet_rsk(req); ireq->loc_addr = daddr; ireq->rmt_addr = saddr; /* FIXME: Merge Aristeu's option parsing code when ready */ req->rcv_wnd = 100; /* Fake, option parsing will get the right value */ ireq->opt = NULL; /* * Step 3: Process LISTEN state * * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie * * In fact we defer setting S.GSR, S.SWL, S.SWH to * dccp_create_openreq_child. */ dreq = dccp_rsk(req); dreq->dreq_isr = DCCP_SKB_CB(skb)->dccpd_seq; dreq->dreq_iss = dccp_v4_init_sequence(sk, skb); dreq->dreq_service = dccp_hdr_request(skb)->dccph_req_service; if (dccp_v4_send_response(sk, req, dst)) goto drop_and_free; inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); return 0; drop_and_free: /* * FIXME: should be reqsk_free after implementing req->rsk_ops */ __reqsk_free(req); drop: DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS); return -1; } /* * The three way handshake has completed - we got a valid ACK or DATAACK - * now create the new socket. * * This is the equivalent of TCP's tcp_v4_syn_recv_sock */ struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb, struct request_sock *req, struct dst_entry *dst) { struct inet_request_sock *ireq; struct inet_sock *newinet; struct dccp_sock *newdp; struct sock *newsk; if (sk_acceptq_is_full(sk)) goto exit_overflow; if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL) goto exit; newsk = dccp_create_openreq_child(sk, req, skb); if (newsk == NULL) goto exit; sk_setup_caps(newsk, dst); newdp = dccp_sk(newsk); newinet = inet_sk(newsk); ireq = inet_rsk(req); newinet->daddr = ireq->rmt_addr; newinet->rcv_saddr = ireq->loc_addr; newinet->saddr = ireq->loc_addr; newinet->opt = ireq->opt; ireq->opt = NULL; newinet->mc_index = inet_iif(skb); newinet->mc_ttl = skb->nh.iph->ttl; newinet->id = jiffies; dccp_sync_mss(newsk, dst_mtu(dst)); __inet_hash(&dccp_hashinfo, newsk, 0); __inet_inherit_port(&dccp_hashinfo, sk, newsk); return newsk; exit_overflow: NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS); exit: NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS); dst_release(dst); return NULL; } static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb) { const struct dccp_hdr *dh = dccp_hdr(skb); const struct iphdr *iph = skb->nh.iph; struct sock *nsk; struct request_sock **prev; /* Find possible connection requests. */ struct request_sock *req = inet_csk_search_req(sk, &prev, dh->dccph_sport, iph->saddr, iph->daddr); if (req != NULL) return dccp_check_req(sk, skb, req, prev); nsk = __inet_lookup_established(&dccp_hashinfo, iph->saddr, dh->dccph_sport, iph->daddr, ntohs(dh->dccph_dport), inet_iif(skb)); if (nsk != NULL) { if (nsk->sk_state != DCCP_TIME_WAIT) { bh_lock_sock(nsk); return nsk; } inet_twsk_put((struct inet_timewait_sock *)nsk); return NULL; } return sk; } int dccp_v4_checksum(const struct sk_buff *skb, const u32 saddr, const u32 daddr) { const struct dccp_hdr* dh = dccp_hdr(skb); int checksum_len; u32 tmp; if (dh->dccph_cscov == 0) checksum_len = skb->len; else { checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32); checksum_len = checksum_len < skb->len ? checksum_len : skb->len; } tmp = csum_partial((unsigned char *)dh, checksum_len, 0); return csum_tcpudp_magic(saddr, daddr, checksum_len, IPPROTO_DCCP, tmp); } static int dccp_v4_verify_checksum(struct sk_buff *skb, const u32 saddr, const u32 daddr) { struct dccp_hdr *dh = dccp_hdr(skb); int checksum_len; u32 tmp; if (dh->dccph_cscov == 0) checksum_len = skb->len; else { checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32); checksum_len = checksum_len < skb->len ? checksum_len : skb->len; } tmp = csum_partial((unsigned char *)dh, checksum_len, 0); return csum_tcpudp_magic(saddr, daddr, checksum_len, IPPROTO_DCCP, tmp) == 0 ? 0 : -1; } static struct dst_entry* dccp_v4_route_skb(struct sock *sk, struct sk_buff *skb) { struct rtable *rt; struct flowi fl = { .oif = ((struct rtable *)skb->dst)->rt_iif, .nl_u = { .ip4_u = { .daddr = skb->nh.iph->saddr, .saddr = skb->nh.iph->daddr, .tos = RT_CONN_FLAGS(sk) } }, .proto = sk->sk_protocol, .uli_u = { .ports = { .sport = dccp_hdr(skb)->dccph_dport, .dport = dccp_hdr(skb)->dccph_sport } } }; if (ip_route_output_flow(&rt, &fl, sk, 0)) { IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES); return NULL; } return &rt->u.dst; } void dccp_v4_ctl_send_reset(struct sk_buff *rxskb) { int err; struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh; const int dccp_hdr_reset_len = sizeof(struct dccp_hdr) + sizeof(struct dccp_hdr_ext) + sizeof(struct dccp_hdr_reset); struct sk_buff *skb; struct dst_entry *dst; /* Never send a reset in response to a reset. */ if (rxdh->dccph_type == DCCP_PKT_RESET) return; if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL) return; dst = dccp_v4_route_skb(dccp_ctl_socket->sk, rxskb); if (dst == NULL) return; skb = alloc_skb(MAX_DCCP_HEADER + 15, GFP_ATOMIC); if (skb == NULL) goto out; /* Reserve space for headers. */ skb_reserve(skb, MAX_DCCP_HEADER); skb->dst = dst_clone(dst); skb->h.raw = skb_push(skb, dccp_hdr_reset_len); dh = dccp_hdr(skb); memset(dh, 0, dccp_hdr_reset_len); /* Build DCCP header and checksum it. */ dh->dccph_type = DCCP_PKT_RESET; dh->dccph_sport = rxdh->dccph_dport; dh->dccph_dport = rxdh->dccph_sport; dh->dccph_doff = dccp_hdr_reset_len / 4; dh->dccph_x = 1; dccp_hdr_reset(skb)->dccph_reset_code = DCCP_SKB_CB(rxskb)->dccpd_reset_code; dccp_hdr_set_seq(dh, DCCP_SKB_CB(rxskb)->dccpd_ack_seq); dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), DCCP_SKB_CB(rxskb)->dccpd_seq); dh->dccph_checksum = dccp_v4_checksum(skb, rxskb->nh.iph->saddr, rxskb->nh.iph->daddr); bh_lock_sock(dccp_ctl_socket->sk); err = ip_build_and_send_pkt(skb, dccp_ctl_socket->sk, rxskb->nh.iph->daddr, rxskb->nh.iph->saddr, NULL); bh_unlock_sock(dccp_ctl_socket->sk); if (err == NET_XMIT_CN || err == 0) { DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS); DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS); } out: dst_release(dst); } int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) { struct dccp_hdr *dh = dccp_hdr(skb); if (sk->sk_state == DCCP_OPEN) { /* Fast path */ if (dccp_rcv_established(sk, skb, dh, skb->len)) goto reset; return 0; } /* * Step 3: Process LISTEN state * If S.state == LISTEN, * If P.type == Request or P contains a valid Init Cookie option, * * Must scan the packet's options to check for an Init * Cookie. Only the Init Cookie is processed here, * however; other options are processed in Step 8. This * scan need only be performed if the endpoint uses Init * Cookies * * * Generate a new socket and switch to that socket * * Set S := new socket for this port pair * S.state = RESPOND * Choose S.ISS (initial seqno) or set from Init Cookie * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie * Continue with S.state == RESPOND * * A Response packet will be generated in Step 11 * * Otherwise, * Generate Reset(No Connection) unless P.type == Reset * Drop packet and return * * NOTE: the check for the packet types is done in dccp_rcv_state_process */ if (sk->sk_state == DCCP_LISTEN) { struct sock *nsk = dccp_v4_hnd_req(sk, skb); if (nsk == NULL) goto discard; if (nsk != sk) { if (dccp_child_process(sk, nsk, skb)) goto reset; return 0; } } if (dccp_rcv_state_process(sk, skb, dh, skb->len)) goto reset; return 0; reset: DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION; dccp_v4_ctl_send_reset(skb); discard: kfree_skb(skb); return 0; } static inline int dccp_invalid_packet(struct sk_buff *skb) { const struct dccp_hdr *dh; if (skb->pkt_type != PACKET_HOST) return 1; if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { dccp_pr_debug("pskb_may_pull failed\n"); return 1; } dh = dccp_hdr(skb); /* If the packet type is not understood, drop packet and return */ if (dh->dccph_type >= DCCP_PKT_INVALID) { dccp_pr_debug("invalid packet type\n"); return 1; } /* * If P.Data Offset is too small for packet type, or too large for * packet, drop packet and return */ if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { dccp_pr_debug("Offset(%u) too small 1\n", dh->dccph_doff); return 1; } if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) { dccp_pr_debug("P.Data Offset(%u) too small 2\n", dh->dccph_doff); return 1; } dh = dccp_hdr(skb); /* * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet * has short sequence numbers), drop packet and return */ if (dh->dccph_x == 0 && dh->dccph_type != DCCP_PKT_DATA && dh->dccph_type != DCCP_PKT_ACK && dh->dccph_type != DCCP_PKT_DATAACK) { dccp_pr_debug("P.type (%s) not Data, Ack nor DataAck and P.X == 0\n", dccp_packet_name(dh->dccph_type)); return 1; } /* If the header checksum is incorrect, drop packet and return */ if (dccp_v4_verify_checksum(skb, skb->nh.iph->saddr, skb->nh.iph->daddr) < 0) { dccp_pr_debug("header checksum is incorrect\n"); return 1; } return 0; } /* this is called when real data arrives */ int dccp_v4_rcv(struct sk_buff *skb) { const struct dccp_hdr *dh; struct sock *sk; int rc; /* Step 1: Check header basics: */ if (dccp_invalid_packet(skb)) goto discard_it; dh = dccp_hdr(skb); #if 0 /* * Use something like this to simulate some DATA/DATAACK loss to test * dccp_ackpkts_add, you'll get something like this on a session that * sends 10 DATA/DATAACK packets: * * dccp_ackpkts_print: 281473596467422 |0,0|3,0|0,0|3,0|0,0|3,0|0,0|3,0|0,1| * * 0, 0 means: DCCP_ACKPKTS_STATE_RECEIVED, RLE == just this packet * 0, 1 means: DCCP_ACKPKTS_STATE_RECEIVED, RLE == two adjacent packets with the same state * 3, 0 means: DCCP_ACKPKTS_STATE_NOT_RECEIVED, RLE == just this packet * * So... * * 281473596467422 was received * 281473596467421 was not received * 281473596467420 was received * 281473596467419 was not received * 281473596467418 was received * 281473596467417 was not received * 281473596467416 was received * 281473596467415 was not received * 281473596467414 was received * 281473596467413 was received (this one was the 3way handshake RESPONSE) * */ if (dh->dccph_type == DCCP_PKT_DATA || dh->dccph_type == DCCP_PKT_DATAACK) { static int discard = 0; if (discard) { discard = 0; goto discard_it; } discard = 1; } #endif DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(skb); DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; dccp_pr_debug("%8.8s " "src=%u.%u.%u.%u@%-5d " "dst=%u.%u.%u.%u@%-5d seq=%llu", dccp_packet_name(dh->dccph_type), NIPQUAD(skb->nh.iph->saddr), ntohs(dh->dccph_sport), NIPQUAD(skb->nh.iph->daddr), ntohs(dh->dccph_dport), (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); if (dccp_packet_without_ack(skb)) { DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; dccp_pr_debug_cat("\n"); } else { DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) DCCP_SKB_CB(skb)->dccpd_ack_seq); } /* Step 2: * Look up flow ID in table and get corresponding socket */ sk = __inet_lookup(&dccp_hashinfo, skb->nh.iph->saddr, dh->dccph_sport, skb->nh.iph->daddr, ntohs(dh->dccph_dport), inet_iif(skb)); /* * Step 2: * If no socket ... * Generate Reset(No Connection) unless P.type == Reset * Drop packet and return */ if (sk == NULL) { dccp_pr_debug("failed to look up flow ID in table and " "get corresponding socket\n"); goto no_dccp_socket; } /* * Step 2: * ... or S.state == TIMEWAIT, * Generate Reset(No Connection) unless P.type == Reset * Drop packet and return */ if (sk->sk_state == DCCP_TIME_WAIT) { dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: " "do_time_wait\n"); goto do_time_wait; } if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) { dccp_pr_debug("xfrm4_policy_check failed\n"); goto discard_and_relse; } if (sk_filter(sk, skb, 0)) { dccp_pr_debug("sk_filter failed\n"); goto discard_and_relse; } skb->dev = NULL; bh_lock_sock(sk); rc = 0; if (!sock_owned_by_user(sk)) rc = dccp_v4_do_rcv(sk, skb); else sk_add_backlog(sk, skb); bh_unlock_sock(sk); sock_put(sk); return rc; no_dccp_socket: if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) goto discard_it; /* * Step 2: * Generate Reset(No Connection) unless P.type == Reset * Drop packet and return */ if (dh->dccph_type != DCCP_PKT_RESET) { DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION; dccp_v4_ctl_send_reset(skb); } discard_it: /* Discard frame. */ kfree_skb(skb); return 0; discard_and_relse: sock_put(sk); goto discard_it; do_time_wait: inet_twsk_put((struct inet_timewait_sock *)sk); goto no_dccp_socket; } static int dccp_v4_init_sock(struct sock *sk) { struct dccp_sock *dp = dccp_sk(sk); static int dccp_ctl_socket_init = 1; dccp_options_init(&dp->dccps_options); if (dp->dccps_options.dccpo_send_ack_vector) { dp->dccps_hc_rx_ackpkts = dccp_ackpkts_alloc(DCCP_MAX_ACK_VECTOR_LEN, GFP_KERNEL); if (dp->dccps_hc_rx_ackpkts == NULL) return -ENOMEM; } /* * FIXME: We're hardcoding the CCID, and doing this at this point makes * the listening (master) sock get CCID control blocks, which is not * necessary, but for now, to not mess with the test userspace apps, * lets leave it here, later the real solution is to do this in a * setsockopt(CCIDs-I-want/accept). -acme */ if (likely(!dccp_ctl_socket_init)) { dp->dccps_hc_rx_ccid = ccid_init(dp->dccps_options.dccpo_ccid, sk); dp->dccps_hc_tx_ccid = ccid_init(dp->dccps_options.dccpo_ccid, sk); if (dp->dccps_hc_rx_ccid == NULL || dp->dccps_hc_tx_ccid == NULL) { ccid_exit(dp->dccps_hc_rx_ccid, sk); ccid_exit(dp->dccps_hc_tx_ccid, sk); dccp_ackpkts_free(dp->dccps_hc_rx_ackpkts); dp->dccps_hc_rx_ackpkts = NULL; dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL; return -ENOMEM; } } else dccp_ctl_socket_init = 0; dccp_init_xmit_timers(sk); inet_csk(sk)->icsk_rto = DCCP_TIMEOUT_INIT; sk->sk_state = DCCP_CLOSED; dp->dccps_mss_cache = 536; dp->dccps_role = DCCP_ROLE_UNDEFINED; return 0; } int dccp_v4_destroy_sock(struct sock *sk) { struct dccp_sock *dp = dccp_sk(sk); /* * DCCP doesn't use sk_qrite_queue, just sk_send_head * for retransmissions */ if (sk->sk_send_head != NULL) { kfree_skb(sk->sk_send_head); sk->sk_send_head = NULL; } /* Clean up a referenced DCCP bind bucket. */ if (inet_csk(sk)->icsk_bind_hash != NULL) inet_put_port(&dccp_hashinfo, sk); dccp_ackpkts_free(dp->dccps_hc_rx_ackpkts); dp->dccps_hc_rx_ackpkts = NULL; ccid_exit(dp->dccps_hc_rx_ccid, sk); ccid_exit(dp->dccps_hc_tx_ccid, sk); dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL; return 0; } static void dccp_v4_reqsk_destructor(struct request_sock *req) { kfree(inet_rsk(req)->opt); } static struct request_sock_ops dccp_request_sock_ops = { .family = PF_INET, .obj_size = sizeof(struct dccp_request_sock), .rtx_syn_ack = dccp_v4_send_response, .send_ack = dccp_v4_reqsk_send_ack, .destructor = dccp_v4_reqsk_destructor, .send_reset = dccp_v4_ctl_send_reset, }; struct proto dccp_v4_prot = { .name = "DCCP", .owner = THIS_MODULE, .close = dccp_close, .connect = dccp_v4_connect, .disconnect = dccp_disconnect, .ioctl = dccp_ioctl, .init = dccp_v4_init_sock, .setsockopt = dccp_setsockopt, .getsockopt = dccp_getsockopt, .sendmsg = dccp_sendmsg, .recvmsg = dccp_recvmsg, .backlog_rcv = dccp_v4_do_rcv, .hash = dccp_v4_hash, .unhash = dccp_v4_unhash, .accept = inet_csk_accept, .get_port = dccp_v4_get_port, .shutdown = dccp_shutdown, .destroy = dccp_v4_destroy_sock, .orphan_count = &dccp_orphan_count, .max_header = MAX_DCCP_HEADER, .obj_size = sizeof(struct dccp_sock), .rsk_prot = &dccp_request_sock_ops, .twsk_obj_size = sizeof(struct inet_timewait_sock), };