diff options
Diffstat (limited to 'net/dccp/ipv4.c')
| -rw-r--r-- | net/dccp/ipv4.c | 1289 |
1 files changed, 1289 insertions, 0 deletions
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c new file mode 100644 index 00000000000..083bacaecb3 --- /dev/null +++ b/net/dccp/ipv4.c @@ -0,0 +1,1289 @@ +/* + * net/dccp/ipv4.c + * + * An implementation of the DCCP protocol + * Arnaldo Carvalho de Melo <acme@conectiva.com.br> + * + * 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 <linux/config.h> +#include <linux/dccp.h> +#include <linux/icmp.h> +#include <linux/module.h> +#include <linux/skbuff.h> +#include <linux/random.h> + +#include <net/icmp.h> +#include <net/inet_hashtables.h> +#include <net/sock.h> +#include <net/tcp_states.h> +#include <net/xfrm.h> + +#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, +}; + +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... */ + dccp_tw_deschedule(tw); + 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) { + dccp_tw_deschedule(tw); + 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(struct sk_buff *skb) +{ + 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_fold(tmp); +} + +static int dccp_v4_verify_checksum(struct sk_buff *skb) +{ + struct dccp_hdr *th = dccp_hdr(skb); + const u16 remote_checksum = th->dccph_checksum; + u16 local_checksum; + + /* FIXME: don't mess with skb payload */ + th->dccph_checksum = 0; /* zero it for computation */ + + local_checksum = dccp_v4_checksum(skb); + + /* FIXME: don't mess with skb payload */ + th->dccph_checksum = remote_checksum; /* put it back */ + + return remote_checksum == local_checksum ? 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); + + 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) < 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), + 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", 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: discard_and_relse\n"); + goto discard_and_relse; + } + + 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; +} + +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); + 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), /* FIXME! create dccp_timewait_sock */ +}; 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