diff options
Diffstat (limited to 'net/dccp/ipv4.c')
| -rw-r--r-- | net/dccp/ipv4.c | 1080 |
1 files changed, 1080 insertions, 0 deletions
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c new file mode 100644 index 000000000..2c7c1bdd3 --- /dev/null +++ b/net/dccp/ipv4.c @@ -0,0 +1,1080 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * net/dccp/ipv4.c + * + * An implementation of the DCCP protocol + * Arnaldo Carvalho de Melo <acme@conectiva.com.br> + */ + +#include <linux/dccp.h> +#include <linux/icmp.h> +#include <linux/slab.h> +#include <linux/module.h> +#include <linux/skbuff.h> +#include <linux/random.h> + +#include <net/icmp.h> +#include <net/inet_common.h> +#include <net/inet_hashtables.h> +#include <net/inet_sock.h> +#include <net/protocol.h> +#include <net/sock.h> +#include <net/timewait_sock.h> +#include <net/tcp_states.h> +#include <net/xfrm.h> +#include <net/secure_seq.h> + +#include "ackvec.h" +#include "ccid.h" +#include "dccp.h" +#include "feat.h" + +/* + * The per-net dccp.v4_ctl_sk socket is used for responding to + * the Out-of-the-blue (OOTB) packets. A control sock will be created + * for this socket at the initialization time. + */ + +int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) +{ + const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr; + struct inet_sock *inet = inet_sk(sk); + struct dccp_sock *dp = dccp_sk(sk); + __be16 orig_sport, orig_dport; + __be32 daddr, nexthop; + struct flowi4 *fl4; + struct rtable *rt; + int err; + struct ip_options_rcu *inet_opt; + + 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; + + inet_opt = rcu_dereference_protected(inet->inet_opt, + lockdep_sock_is_held(sk)); + if (inet_opt != NULL && inet_opt->opt.srr) { + if (daddr == 0) + return -EINVAL; + nexthop = inet_opt->opt.faddr; + } + + orig_sport = inet->inet_sport; + orig_dport = usin->sin_port; + fl4 = &inet->cork.fl.u.ip4; + rt = ip_route_connect(fl4, nexthop, inet->inet_saddr, + RT_CONN_FLAGS(sk), sk->sk_bound_dev_if, + IPPROTO_DCCP, + orig_sport, orig_dport, sk); + if (IS_ERR(rt)) + return PTR_ERR(rt); + + if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { + ip_rt_put(rt); + return -ENETUNREACH; + } + + if (inet_opt == NULL || !inet_opt->opt.srr) + daddr = fl4->daddr; + + if (inet->inet_saddr == 0) + inet->inet_saddr = fl4->saddr; + sk_rcv_saddr_set(sk, inet->inet_saddr); + inet->inet_dport = usin->sin_port; + sk_daddr_set(sk, daddr); + + inet_csk(sk)->icsk_ext_hdr_len = 0; + if (inet_opt) + inet_csk(sk)->icsk_ext_hdr_len = inet_opt->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 = inet_hash_connect(&dccp_death_row, sk); + if (err != 0) + goto failure; + + rt = ip_route_newports(fl4, rt, orig_sport, orig_dport, + inet->inet_sport, inet->inet_dport, sk); + if (IS_ERR(rt)) { + err = PTR_ERR(rt); + rt = NULL; + goto failure; + } + /* OK, now commit destination to socket. */ + sk_setup_caps(sk, &rt->dst); + + dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr, + inet->inet_daddr, + inet->inet_sport, + inet->inet_dport); + inet->inet_id = prandom_u32(); + + 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); + if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK)) + inet_reset_saddr(sk); + ip_rt_put(rt); + sk->sk_route_caps = 0; + inet->inet_dport = 0; + goto out; +} +EXPORT_SYMBOL_GPL(dccp_v4_connect); + +/* + * 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; + + dst = inet_csk_update_pmtu(sk, mtu); + if (!dst) + return; + + /* 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 && + ip_sk_accept_pmtu(sk) && + inet_csk(sk)->icsk_pmtu_cookie > mtu) { + dccp_sync_mss(sk, mtu); + + /* + * From RFC 4340, sec. 14.1: + * + * 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, DCCP_PKT_SYNC); + } /* else let the usual retransmit timer handle it */ +} + +static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk) +{ + struct dst_entry *dst = __sk_dst_check(sk, 0); + + if (dst) + dst->ops->redirect(dst, sk, skb); +} + +void dccp_req_err(struct sock *sk, u64 seq) + { + struct request_sock *req = inet_reqsk(sk); + struct net *net = sock_net(sk); + + /* + * ICMPs are not backlogged, hence we cannot get an established + * socket here. + */ + if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) { + __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); + } else { + /* + * 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(req->rsk_listener, req); + } + reqsk_put(req); +} +EXPORT_SYMBOL(dccp_req_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. + */ +static int dccp_v4_err(struct sk_buff *skb, u32 info) +{ + const struct iphdr *iph = (struct iphdr *)skb->data; + const u8 offset = iph->ihl << 2; + const struct dccp_hdr *dh; + struct dccp_sock *dp; + struct inet_sock *inet; + const int type = icmp_hdr(skb)->type; + const int code = icmp_hdr(skb)->code; + struct sock *sk; + __u64 seq; + int err; + struct net *net = dev_net(skb->dev); + + if (!pskb_may_pull(skb, offset + sizeof(*dh))) + return -EINVAL; + dh = (struct dccp_hdr *)(skb->data + offset); + if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh))) + return -EINVAL; + iph = (struct iphdr *)skb->data; + dh = (struct dccp_hdr *)(skb->data + offset); + + sk = __inet_lookup_established(net, &dccp_hashinfo, + iph->daddr, dh->dccph_dport, + iph->saddr, ntohs(dh->dccph_sport), + inet_iif(skb), 0); + if (!sk) { + __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); + return -ENOENT; + } + + if (sk->sk_state == DCCP_TIME_WAIT) { + inet_twsk_put(inet_twsk(sk)); + return 0; + } + seq = dccp_hdr_seq(dh); + if (sk->sk_state == DCCP_NEW_SYN_RECV) { + dccp_req_err(sk, seq); + return 0; + } + + 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(net, LINUX_MIB_LOCKDROPPEDICMPS); + + if (sk->sk_state == DCCP_CLOSED) + goto out; + + dp = dccp_sk(sk); + if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && + !between48(seq, dp->dccps_awl, dp->dccps_awh)) { + __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); + goto out; + } + + switch (type) { + case ICMP_REDIRECT: + if (!sock_owned_by_user(sk)) + dccp_do_redirect(skb, sk); + goto out; + 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) { + case DCCP_REQUESTING: + case DCCP_RESPOND: + if (!sock_owned_by_user(sk)) { + __DCCP_INC_STATS(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); + return 0; +} + +static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, + __be32 src, __be32 dst) +{ + return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); +} + +void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) +{ + const struct inet_sock *inet = inet_sk(sk); + struct dccp_hdr *dh = dccp_hdr(skb); + + dccp_csum_outgoing(skb); + dh->dccph_checksum = dccp_v4_csum_finish(skb, + inet->inet_saddr, + inet->inet_daddr); +} +EXPORT_SYMBOL_GPL(dccp_v4_send_check); + +static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) +{ + return secure_dccp_sequence_number(ip_hdr(skb)->daddr, + ip_hdr(skb)->saddr, + dccp_hdr(skb)->dccph_dport, + dccp_hdr(skb)->dccph_sport); +} + +/* + * 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(const struct sock *sk, + struct sk_buff *skb, + struct request_sock *req, + struct dst_entry *dst, + struct request_sock *req_unhash, + bool *own_req) +{ + struct inet_request_sock *ireq; + struct inet_sock *newinet; + struct sock *newsk; + + if (sk_acceptq_is_full(sk)) + goto exit_overflow; + + newsk = dccp_create_openreq_child(sk, req, skb); + if (newsk == NULL) + goto exit_nonewsk; + + newinet = inet_sk(newsk); + ireq = inet_rsk(req); + sk_daddr_set(newsk, ireq->ir_rmt_addr); + sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); + newinet->inet_saddr = ireq->ir_loc_addr; + RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt)); + newinet->mc_index = inet_iif(skb); + newinet->mc_ttl = ip_hdr(skb)->ttl; + newinet->inet_id = prandom_u32(); + + if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) + goto put_and_exit; + + sk_setup_caps(newsk, dst); + + dccp_sync_mss(newsk, dst_mtu(dst)); + + if (__inet_inherit_port(sk, newsk) < 0) + goto put_and_exit; + *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL); + if (*own_req) + ireq->ireq_opt = NULL; + else + newinet->inet_opt = NULL; + return newsk; + +exit_overflow: + __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); +exit_nonewsk: + dst_release(dst); +exit: + __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); + return NULL; +put_and_exit: + newinet->inet_opt = NULL; + inet_csk_prepare_forced_close(newsk); + dccp_done(newsk); + goto exit; +} +EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); + +static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, + struct sk_buff *skb) +{ + struct rtable *rt; + const struct iphdr *iph = ip_hdr(skb); + struct flowi4 fl4 = { + .flowi4_oif = inet_iif(skb), + .daddr = iph->saddr, + .saddr = iph->daddr, + .flowi4_tos = RT_CONN_FLAGS(sk), + .flowi4_proto = sk->sk_protocol, + .fl4_sport = dccp_hdr(skb)->dccph_dport, + .fl4_dport = dccp_hdr(skb)->dccph_sport, + }; + + security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); + rt = ip_route_output_flow(net, &fl4, sk); + if (IS_ERR(rt)) { + IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); + return NULL; + } + + return &rt->dst; +} + +static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req) +{ + int err = -1; + struct sk_buff *skb; + struct dst_entry *dst; + struct flowi4 fl4; + + dst = inet_csk_route_req(sk, &fl4, req); + if (dst == NULL) + goto out; + + skb = dccp_make_response(sk, dst, req); + if (skb != NULL) { + const struct inet_request_sock *ireq = inet_rsk(req); + struct dccp_hdr *dh = dccp_hdr(skb); + + dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, + ireq->ir_rmt_addr); + rcu_read_lock(); + err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, + ireq->ir_rmt_addr, + rcu_dereference(ireq->ireq_opt), + inet_sk(sk)->tos); + rcu_read_unlock(); + err = net_xmit_eval(err); + } + +out: + dst_release(dst); + return err; +} + +static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb) +{ + int err; + const struct iphdr *rxiph; + struct sk_buff *skb; + struct dst_entry *dst; + struct net *net = dev_net(skb_dst(rxskb)->dev); + struct sock *ctl_sk = net->dccp.v4_ctl_sk; + + /* Never send a reset in response to a reset. */ + if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) + return; + + if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) + return; + + dst = dccp_v4_route_skb(net, ctl_sk, rxskb); + if (dst == NULL) + return; + + skb = dccp_ctl_make_reset(ctl_sk, rxskb); + if (skb == NULL) + goto out; + + rxiph = ip_hdr(rxskb); + dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, + rxiph->daddr); + skb_dst_set(skb, dst_clone(dst)); + + local_bh_disable(); + bh_lock_sock(ctl_sk); + err = ip_build_and_send_pkt(skb, ctl_sk, + rxiph->daddr, rxiph->saddr, NULL, + inet_sk(ctl_sk)->tos); + bh_unlock_sock(ctl_sk); + + if (net_xmit_eval(err) == 0) { + __DCCP_INC_STATS(DCCP_MIB_OUTSEGS); + __DCCP_INC_STATS(DCCP_MIB_OUTRSTS); + } + local_bh_enable(); +out: + dst_release(dst); +} + +static void dccp_v4_reqsk_destructor(struct request_sock *req) +{ + dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); + kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1)); +} + +void dccp_syn_ack_timeout(const struct request_sock *req) +{ +} +EXPORT_SYMBOL(dccp_syn_ack_timeout); + +static struct request_sock_ops dccp_request_sock_ops __read_mostly = { + .family = PF_INET, + .obj_size = sizeof(struct dccp_request_sock), + .rtx_syn_ack = dccp_v4_send_response, + .send_ack = dccp_reqsk_send_ack, + .destructor = dccp_v4_reqsk_destructor, + .send_reset = dccp_v4_ctl_send_reset, + .syn_ack_timeout = dccp_syn_ack_timeout, +}; + +int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) +{ + struct inet_request_sock *ireq; + struct request_sock *req; + struct dccp_request_sock *dreq; + const __be32 service = dccp_hdr_request(skb)->dccph_req_service; + struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); + + /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ + if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) + return 0; /* discard, don't send a reset here */ + + if (dccp_bad_service_code(sk, service)) { + dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; + goto drop; + } + /* + * TW buckets are converted to open requests without + * limitations, they conserve resources and peer is + * evidently real one. + */ + dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; + if (inet_csk_reqsk_queue_is_full(sk)) + goto drop; + + if (sk_acceptq_is_full(sk)) + goto drop; + + req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true); + if (req == NULL) + goto drop; + + if (dccp_reqsk_init(req, dccp_sk(sk), skb)) + goto drop_and_free; + + dreq = dccp_rsk(req); + if (dccp_parse_options(sk, dreq, skb)) + goto drop_and_free; + + ireq = inet_rsk(req); + sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); + sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); + ireq->ir_mark = inet_request_mark(sk, skb); + ireq->ireq_family = AF_INET; + ireq->ir_iif = sk->sk_bound_dev_if; + + if (security_inet_conn_request(sk, skb, req)) + goto drop_and_free; + + /* + * Step 3: Process LISTEN state + * + * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie + * + * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child(). + */ + dreq->dreq_isr = dcb->dccpd_seq; + dreq->dreq_gsr = dreq->dreq_isr; + dreq->dreq_iss = dccp_v4_init_sequence(skb); + dreq->dreq_gss = dreq->dreq_iss; + dreq->dreq_service = service; + + if (dccp_v4_send_response(sk, req)) + goto drop_and_free; + + inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); + reqsk_put(req); + return 0; + +drop_and_free: + reqsk_free(req); +drop: + __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); + return -1; +} +EXPORT_SYMBOL_GPL(dccp_v4_conn_request); + +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 P.type == Request or P contains a valid Init Cookie option, + * (* Must scan the packet's options to check for Init + * Cookies. Only Init Cookies are 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 Cookies + * Initialize S.GAR := S.ISS + * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies + * 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 (dccp_rcv_state_process(sk, skb, dh, skb->len)) + goto reset; + return 0; + +reset: + dccp_v4_ctl_send_reset(sk, skb); + kfree_skb(skb); + return 0; +} +EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); + +/** + * dccp_invalid_packet - check for malformed packets + * @skb: Packet to validate + * + * Implements RFC 4340, 8.5: Step 1: Check header basics + * Packets that fail these checks are ignored and do not receive Resets. + */ +int dccp_invalid_packet(struct sk_buff *skb) +{ + const struct dccp_hdr *dh; + unsigned int cscov; + u8 dccph_doff; + + if (skb->pkt_type != PACKET_HOST) + return 1; + + /* If the packet is shorter than 12 bytes, drop packet and return */ + if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { + DCCP_WARN("pskb_may_pull failed\n"); + return 1; + } + + dh = dccp_hdr(skb); + + /* If P.type is not understood, drop packet and return */ + if (dh->dccph_type >= DCCP_PKT_INVALID) { + DCCP_WARN("invalid packet type\n"); + return 1; + } + + /* + * If P.Data Offset is too small for packet type, drop packet and return + */ + dccph_doff = dh->dccph_doff; + if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { + DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff); + return 1; + } + /* + * If P.Data Offset is too large for packet, drop packet and return + */ + if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) { + DCCP_WARN("P.Data Offset(%u) too large\n", 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_type < DCCP_PKT_DATA || + dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { + DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", + dccp_packet_name(dh->dccph_type)); + return 1; + } + + /* + * If P.CsCov is too large for the packet size, drop packet and return. + * This must come _before_ checksumming (not as RFC 4340 suggests). + */ + cscov = dccp_csum_coverage(skb); + if (cscov > skb->len) { + DCCP_WARN("P.CsCov %u exceeds packet length %d\n", + dh->dccph_cscov, skb->len); + return 1; + } + + /* If header checksum is incorrect, drop packet and return. + * (This step is completed in the AF-dependent functions.) */ + skb->csum = skb_checksum(skb, 0, cscov, 0); + + return 0; +} +EXPORT_SYMBOL_GPL(dccp_invalid_packet); + +/* this is called when real data arrives */ +static int dccp_v4_rcv(struct sk_buff *skb) +{ + const struct dccp_hdr *dh; + const struct iphdr *iph; + bool refcounted; + struct sock *sk; + int min_cov; + + /* Step 1: Check header basics */ + + if (dccp_invalid_packet(skb)) + goto discard_it; + + iph = ip_hdr(skb); + /* Step 1: If header checksum is incorrect, drop packet and return */ + if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { + DCCP_WARN("dropped packet with invalid checksum\n"); + goto discard_it; + } + + dh = dccp_hdr(skb); + + DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); + DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; + + dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", + dccp_packet_name(dh->dccph_type), + &iph->saddr, ntohs(dh->dccph_sport), + &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); + } + +lookup: + sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh), + dh->dccph_sport, dh->dccph_dport, 0, &refcounted); + if (!sk) { + 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"); + inet_twsk_put(inet_twsk(sk)); + goto no_dccp_socket; + } + + if (sk->sk_state == DCCP_NEW_SYN_RECV) { + struct request_sock *req = inet_reqsk(sk); + struct sock *nsk; + + sk = req->rsk_listener; + if (unlikely(sk->sk_state != DCCP_LISTEN)) { + inet_csk_reqsk_queue_drop_and_put(sk, req); + goto lookup; + } + sock_hold(sk); + refcounted = true; + nsk = dccp_check_req(sk, skb, req); + if (!nsk) { + reqsk_put(req); + goto discard_and_relse; + } + if (nsk == sk) { + reqsk_put(req); + } else if (dccp_child_process(sk, nsk, skb)) { + dccp_v4_ctl_send_reset(sk, skb); + goto discard_and_relse; + } else { + sock_put(sk); + return 0; + } + } + /* + * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage + * o if MinCsCov = 0, only packets with CsCov = 0 are accepted + * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov + */ + min_cov = dccp_sk(sk)->dccps_pcrlen; + if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { + dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", + dh->dccph_cscov, min_cov); + /* FIXME: "Such packets SHOULD be reported using Data Dropped + * options (Section 11.7) with Drop Code 0, Protocol + * Constraints." */ + goto discard_and_relse; + } + + if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) + goto discard_and_relse; + nf_reset_ct(skb); + + return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted); + +no_dccp_socket: + if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) + goto discard_it; + /* + * Step 2: + * If no socket ... + * 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(sk, skb); + } + +discard_it: + kfree_skb(skb); + return 0; + +discard_and_relse: + if (refcounted) + sock_put(sk); + goto discard_it; +} + +static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { + .queue_xmit = ip_queue_xmit, + .send_check = dccp_v4_send_check, + .rebuild_header = inet_sk_rebuild_header, + .conn_request = dccp_v4_conn_request, + .syn_recv_sock = dccp_v4_request_recv_sock, + .net_header_len = sizeof(struct iphdr), + .setsockopt = ip_setsockopt, + .getsockopt = ip_getsockopt, + .addr2sockaddr = inet_csk_addr2sockaddr, + .sockaddr_len = sizeof(struct sockaddr_in), +}; + +static int dccp_v4_init_sock(struct sock *sk) +{ + static __u8 dccp_v4_ctl_sock_initialized; + int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); + + if (err == 0) { + if (unlikely(!dccp_v4_ctl_sock_initialized)) + dccp_v4_ctl_sock_initialized = 1; + inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; + } + + return err; +} + +static struct timewait_sock_ops dccp_timewait_sock_ops = { + .twsk_obj_size = sizeof(struct inet_timewait_sock), +}; + +static 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 = inet_hash, + .unhash = inet_unhash, + .accept = inet_csk_accept, + .get_port = inet_csk_get_port, + .shutdown = dccp_shutdown, + .destroy = dccp_destroy_sock, + .orphan_count = &dccp_orphan_count, + .max_header = MAX_DCCP_HEADER, + .obj_size = sizeof(struct dccp_sock), + .slab_flags = SLAB_TYPESAFE_BY_RCU, + .rsk_prot = &dccp_request_sock_ops, + .twsk_prot = &dccp_timewait_sock_ops, + .h.hashinfo = &dccp_hashinfo, +}; + +static const struct net_protocol dccp_v4_protocol = { + .handler = dccp_v4_rcv, + .err_handler = dccp_v4_err, + .no_policy = 1, + .netns_ok = 1, + .icmp_strict_tag_validation = 1, +}; + +static const struct proto_ops inet_dccp_ops = { + .family = PF_INET, + .owner = THIS_MODULE, + .release = inet_release, + .bind = inet_bind, + .connect = inet_stream_connect, + .socketpair = sock_no_socketpair, + .accept = inet_accept, + .getname = inet_getname, + /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ + .poll = dccp_poll, + .ioctl = inet_ioctl, + .gettstamp = sock_gettstamp, + /* FIXME: work on inet_listen to rename it to sock_common_listen */ + .listen = inet_dccp_listen, + .shutdown = inet_shutdown, + .setsockopt = sock_common_setsockopt, + .getsockopt = sock_common_getsockopt, + .sendmsg = inet_sendmsg, + .recvmsg = sock_common_recvmsg, + .mmap = sock_no_mmap, + .sendpage = sock_no_sendpage, +}; + +static struct inet_protosw dccp_v4_protosw = { + .type = SOCK_DCCP, + .protocol = IPPROTO_DCCP, + .prot = &dccp_v4_prot, + .ops = &inet_dccp_ops, + .flags = INET_PROTOSW_ICSK, +}; + +static int __net_init dccp_v4_init_net(struct net *net) +{ + if (dccp_hashinfo.bhash == NULL) + return -ESOCKTNOSUPPORT; + + return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET, + SOCK_DCCP, IPPROTO_DCCP, net); +} + +static void __net_exit dccp_v4_exit_net(struct net *net) +{ + inet_ctl_sock_destroy(net->dccp.v4_ctl_sk); +} + +static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list) +{ + inet_twsk_purge(&dccp_hashinfo, AF_INET); +} + +static struct pernet_operations dccp_v4_ops = { + .init = dccp_v4_init_net, + .exit = dccp_v4_exit_net, + .exit_batch = dccp_v4_exit_batch, +}; + +static int __init dccp_v4_init(void) +{ + int err = proto_register(&dccp_v4_prot, 1); + + if (err) + goto out; + + inet_register_protosw(&dccp_v4_protosw); + + err = register_pernet_subsys(&dccp_v4_ops); + if (err) + goto out_destroy_ctl_sock; + + err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); + if (err) + goto out_proto_unregister; + +out: + return err; +out_proto_unregister: + unregister_pernet_subsys(&dccp_v4_ops); +out_destroy_ctl_sock: + inet_unregister_protosw(&dccp_v4_protosw); + proto_unregister(&dccp_v4_prot); + goto out; +} + +static void __exit dccp_v4_exit(void) +{ + inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); + unregister_pernet_subsys(&dccp_v4_ops); + inet_unregister_protosw(&dccp_v4_protosw); + proto_unregister(&dccp_v4_prot); +} + +module_init(dccp_v4_init); +module_exit(dccp_v4_exit); + +/* + * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) + * values directly, Also cover the case where the protocol is not specified, + * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP + */ +MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); +MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); +MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); |