File-copy from v4.4.100
This is the result of 'cp' from a linux-stable tree with the 'v4.4.100'
tag checked out (commit 26d6298789e695c9f627ce49a7bbd2286405798a) on
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Please refer to that tree for all history prior to this point.
Change-Id: I8a9ee2aea93cd29c52c847d0ce33091a73ae6afe
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
new file mode 100644
index 0000000..a5d790c
--- /dev/null
+++ b/net/ipv4/tcp_ipv4.c
@@ -0,0 +1,2442 @@
+/*
+ * INET An implementation of the TCP/IP protocol suite for the LINUX
+ * operating system. INET is implemented using the BSD Socket
+ * interface as the means of communication with the user level.
+ *
+ * Implementation of the Transmission Control Protocol(TCP).
+ *
+ * IPv4 specific functions
+ *
+ *
+ * code split from:
+ * linux/ipv4/tcp.c
+ * linux/ipv4/tcp_input.c
+ * linux/ipv4/tcp_output.c
+ *
+ * See tcp.c for author information
+ *
+ * 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.
+ */
+
+/*
+ * Changes:
+ * David S. Miller : New socket lookup architecture.
+ * This code is dedicated to John Dyson.
+ * David S. Miller : Change semantics of established hash,
+ * half is devoted to TIME_WAIT sockets
+ * and the rest go in the other half.
+ * Andi Kleen : Add support for syncookies and fixed
+ * some bugs: ip options weren't passed to
+ * the TCP layer, missed a check for an
+ * ACK bit.
+ * Andi Kleen : Implemented fast path mtu discovery.
+ * Fixed many serious bugs in the
+ * request_sock handling and moved
+ * most of it into the af independent code.
+ * Added tail drop and some other bugfixes.
+ * Added new listen semantics.
+ * Mike McLagan : Routing by source
+ * Juan Jose Ciarlante: ip_dynaddr bits
+ * Andi Kleen: various fixes.
+ * Vitaly E. Lavrov : Transparent proxy revived after year
+ * coma.
+ * Andi Kleen : Fix new listen.
+ * Andi Kleen : Fix accept error reporting.
+ * YOSHIFUJI Hideaki @USAGI and: Support IPV6_V6ONLY socket option, which
+ * Alexey Kuznetsov allow both IPv4 and IPv6 sockets to bind
+ * a single port at the same time.
+ */
+
+#define pr_fmt(fmt) "TCP: " fmt
+
+#include <linux/bottom_half.h>
+#include <linux/types.h>
+#include <linux/fcntl.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/cache.h>
+#include <linux/jhash.h>
+#include <linux/init.h>
+#include <linux/times.h>
+#include <linux/slab.h>
+
+#include <net/net_namespace.h>
+#include <net/icmp.h>
+#include <net/inet_hashtables.h>
+#include <net/tcp.h>
+#include <net/transp_v6.h>
+#include <net/ipv6.h>
+#include <net/inet_common.h>
+#include <net/timewait_sock.h>
+#include <net/xfrm.h>
+#include <net/secure_seq.h>
+#include <net/tcp_memcontrol.h>
+#include <net/busy_poll.h>
+
+#include <linux/inet.h>
+#include <linux/ipv6.h>
+#include <linux/stddef.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+
+#include <linux/crypto.h>
+#include <linux/scatterlist.h>
+
+int sysctl_tcp_tw_reuse __read_mostly;
+int sysctl_tcp_low_latency __read_mostly;
+EXPORT_SYMBOL(sysctl_tcp_low_latency);
+
+#ifdef CONFIG_TCP_MD5SIG
+static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
+ __be32 daddr, __be32 saddr, const struct tcphdr *th);
+#endif
+
+struct inet_hashinfo tcp_hashinfo;
+EXPORT_SYMBOL(tcp_hashinfo);
+
+static __u32 tcp_v4_init_sequence(const struct sk_buff *skb)
+{
+ return secure_tcp_sequence_number(ip_hdr(skb)->daddr,
+ ip_hdr(skb)->saddr,
+ tcp_hdr(skb)->dest,
+ tcp_hdr(skb)->source);
+}
+
+int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
+{
+ const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw);
+ struct tcp_sock *tp = tcp_sk(sk);
+
+ /* With PAWS, it is safe from the viewpoint
+ of data integrity. Even without PAWS it is safe provided sequence
+ spaces do not overlap i.e. at data rates <= 80Mbit/sec.
+
+ Actually, the idea is close to VJ's one, only timestamp cache is
+ held not per host, but per port pair and TW bucket is used as state
+ holder.
+
+ If TW bucket has been already destroyed we fall back to VJ's scheme
+ and use initial timestamp retrieved from peer table.
+ */
+ if (tcptw->tw_ts_recent_stamp &&
+ (!twp || (sysctl_tcp_tw_reuse &&
+ get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
+ tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
+ if (tp->write_seq == 0)
+ tp->write_seq = 1;
+ tp->rx_opt.ts_recent = tcptw->tw_ts_recent;
+ tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
+ sock_hold(sktw);
+ return 1;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(tcp_twsk_unique);
+
+/* This will initiate an outgoing connection. */
+int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
+{
+ struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
+ struct inet_sock *inet = inet_sk(sk);
+ struct tcp_sock *tp = tcp_sk(sk);
+ __be16 orig_sport, orig_dport;
+ __be32 daddr, nexthop;
+ struct flowi4 *fl4;
+ struct rtable *rt;
+ int err;
+ struct ip_options_rcu *inet_opt;
+
+ 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,
+ sock_owned_by_user(sk));
+ if (inet_opt && inet_opt->opt.srr) {
+ if (!daddr)
+ 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_TCP,
+ orig_sport, orig_dport, sk);
+ if (IS_ERR(rt)) {
+ err = PTR_ERR(rt);
+ if (err == -ENETUNREACH)
+ IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
+ return err;
+ }
+
+ if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
+ ip_rt_put(rt);
+ return -ENETUNREACH;
+ }
+
+ if (!inet_opt || !inet_opt->opt.srr)
+ daddr = fl4->daddr;
+
+ if (!inet->inet_saddr)
+ inet->inet_saddr = fl4->saddr;
+ sk_rcv_saddr_set(sk, inet->inet_saddr);
+
+ if (tp->rx_opt.ts_recent_stamp && inet->inet_daddr != daddr) {
+ /* Reset inherited state */
+ tp->rx_opt.ts_recent = 0;
+ tp->rx_opt.ts_recent_stamp = 0;
+ if (likely(!tp->repair))
+ tp->write_seq = 0;
+ }
+
+ if (tcp_death_row.sysctl_tw_recycle &&
+ !tp->rx_opt.ts_recent_stamp && fl4->daddr == daddr)
+ tcp_fetch_timewait_stamp(sk, &rt->dst);
+
+ 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;
+
+ tp->rx_opt.mss_clamp = TCP_MSS_DEFAULT;
+
+ /* Socket identity is still unknown (sport may be zero).
+ * However we set state to SYN-SENT and not releasing socket
+ * lock select source port, enter ourselves into the hash tables and
+ * complete initialization after this.
+ */
+ tcp_set_state(sk, TCP_SYN_SENT);
+ err = inet_hash_connect(&tcp_death_row, sk);
+ if (err)
+ goto failure;
+
+ sk_set_txhash(sk);
+
+ 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->sk_gso_type = SKB_GSO_TCPV4;
+ sk_setup_caps(sk, &rt->dst);
+
+ if (!tp->write_seq && likely(!tp->repair))
+ tp->write_seq = secure_tcp_sequence_number(inet->inet_saddr,
+ inet->inet_daddr,
+ inet->inet_sport,
+ usin->sin_port);
+
+ inet->inet_id = tp->write_seq ^ jiffies;
+
+ err = tcp_connect(sk);
+
+ rt = NULL;
+ if (err)
+ goto failure;
+
+ return 0;
+
+failure:
+ /*
+ * This unhashes the socket and releases the local port,
+ * if necessary.
+ */
+ tcp_set_state(sk, TCP_CLOSE);
+ ip_rt_put(rt);
+ sk->sk_route_caps = 0;
+ inet->inet_dport = 0;
+ return err;
+}
+EXPORT_SYMBOL(tcp_v4_connect);
+
+/*
+ * This routine reacts to ICMP_FRAG_NEEDED mtu indications as defined in RFC1191.
+ * It can be called through tcp_release_cb() if socket was owned by user
+ * at the time tcp_v4_err() was called to handle ICMP message.
+ */
+void tcp_v4_mtu_reduced(struct sock *sk)
+{
+ struct inet_sock *inet = inet_sk(sk);
+ struct dst_entry *dst;
+ u32 mtu;
+
+ if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE))
+ return;
+ mtu = tcp_sk(sk)->mtu_info;
+ 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) {
+ tcp_sync_mss(sk, mtu);
+
+ /* Resend the TCP packet because it's
+ * clear that the old packet has been
+ * dropped. This is the new "fast" path mtu
+ * discovery.
+ */
+ tcp_simple_retransmit(sk);
+ } /* else let the usual retransmit timer handle it */
+}
+EXPORT_SYMBOL(tcp_v4_mtu_reduced);
+
+static void 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);
+}
+
+
+/* handle ICMP messages on TCP_NEW_SYN_RECV request sockets */
+void tcp_req_err(struct sock *sk, u32 seq, bool abort)
+{
+ 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 (seq != tcp_rsk(req)->snt_isn) {
+ NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
+ } else if (abort) {
+ /*
+ * Still in SYN_RECV, 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);
+ NET_INC_STATS_BH(net, LINUX_MIB_LISTENDROPS);
+ }
+ reqsk_put(req);
+}
+EXPORT_SYMBOL(tcp_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.
+ *
+ */
+
+void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
+{
+ const struct iphdr *iph = (const struct iphdr *)icmp_skb->data;
+ struct tcphdr *th = (struct tcphdr *)(icmp_skb->data + (iph->ihl << 2));
+ struct inet_connection_sock *icsk;
+ struct tcp_sock *tp;
+ struct inet_sock *inet;
+ const int type = icmp_hdr(icmp_skb)->type;
+ const int code = icmp_hdr(icmp_skb)->code;
+ struct sock *sk;
+ struct sk_buff *skb;
+ struct request_sock *fastopen;
+ __u32 seq, snd_una;
+ __u32 remaining;
+ int err;
+ struct net *net = dev_net(icmp_skb->dev);
+
+ sk = __inet_lookup_established(net, &tcp_hashinfo, iph->daddr,
+ th->dest, iph->saddr, ntohs(th->source),
+ inet_iif(icmp_skb));
+ if (!sk) {
+ ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
+ return;
+ }
+ if (sk->sk_state == TCP_TIME_WAIT) {
+ inet_twsk_put(inet_twsk(sk));
+ return;
+ }
+ seq = ntohl(th->seq);
+ if (sk->sk_state == TCP_NEW_SYN_RECV)
+ return tcp_req_err(sk, seq,
+ type == ICMP_PARAMETERPROB ||
+ type == ICMP_TIME_EXCEEDED ||
+ (type == ICMP_DEST_UNREACH &&
+ (code == ICMP_NET_UNREACH ||
+ code == ICMP_HOST_UNREACH)));
+
+ bh_lock_sock(sk);
+ /* If too many ICMPs get dropped on busy
+ * servers this needs to be solved differently.
+ * We do take care of PMTU discovery (RFC1191) special case :
+ * we can receive locally generated ICMP messages while socket is held.
+ */
+ if (sock_owned_by_user(sk)) {
+ if (!(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED))
+ NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
+ }
+ if (sk->sk_state == TCP_CLOSE)
+ goto out;
+
+ if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
+ NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
+ goto out;
+ }
+
+ icsk = inet_csk(sk);
+ tp = tcp_sk(sk);
+ /* XXX (TFO) - tp->snd_una should be ISN (tcp_create_openreq_child() */
+ fastopen = tp->fastopen_rsk;
+ snd_una = fastopen ? tcp_rsk(fastopen)->snt_isn : tp->snd_una;
+ if (sk->sk_state != TCP_LISTEN &&
+ !between(seq, snd_una, tp->snd_nxt)) {
+ NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
+ goto out;
+ }
+
+ switch (type) {
+ case ICMP_REDIRECT:
+ if (!sock_owned_by_user(sk))
+ do_redirect(icmp_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) */
+ /* We are not interested in TCP_LISTEN and open_requests
+ * (SYN-ACKs send out by Linux are always <576bytes so
+ * they should go through unfragmented).
+ */
+ if (sk->sk_state == TCP_LISTEN)
+ goto out;
+
+ tp->mtu_info = info;
+ if (!sock_owned_by_user(sk)) {
+ tcp_v4_mtu_reduced(sk);
+ } else {
+ if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED, &tp->tsq_flags))
+ sock_hold(sk);
+ }
+ goto out;
+ }
+
+ err = icmp_err_convert[code].errno;
+ /* check if icmp_skb allows revert of backoff
+ * (see draft-zimmermann-tcp-lcd) */
+ if (code != ICMP_NET_UNREACH && code != ICMP_HOST_UNREACH)
+ break;
+ if (seq != tp->snd_una || !icsk->icsk_retransmits ||
+ !icsk->icsk_backoff || fastopen)
+ break;
+
+ if (sock_owned_by_user(sk))
+ break;
+
+ icsk->icsk_backoff--;
+ icsk->icsk_rto = tp->srtt_us ? __tcp_set_rto(tp) :
+ TCP_TIMEOUT_INIT;
+ icsk->icsk_rto = inet_csk_rto_backoff(icsk, TCP_RTO_MAX);
+
+ skb = tcp_write_queue_head(sk);
+ BUG_ON(!skb);
+
+ remaining = icsk->icsk_rto -
+ min(icsk->icsk_rto,
+ tcp_time_stamp - tcp_skb_timestamp(skb));
+
+ if (remaining) {
+ inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
+ remaining, TCP_RTO_MAX);
+ } else {
+ /* RTO revert clocked out retransmission.
+ * Will retransmit now */
+ tcp_retransmit_timer(sk);
+ }
+
+ break;
+ case ICMP_TIME_EXCEEDED:
+ err = EHOSTUNREACH;
+ break;
+ default:
+ goto out;
+ }
+
+ switch (sk->sk_state) {
+ case TCP_SYN_SENT:
+ case TCP_SYN_RECV:
+ /* Only in fast or simultaneous open. If a fast open socket is
+ * is already accepted it is treated as a connected one below.
+ */
+ if (fastopen && !fastopen->sk)
+ break;
+
+ if (!sock_owned_by_user(sk)) {
+ sk->sk_err = err;
+
+ sk->sk_error_report(sk);
+
+ tcp_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);
+}
+
+void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr)
+{
+ struct tcphdr *th = tcp_hdr(skb);
+
+ if (skb->ip_summed == CHECKSUM_PARTIAL) {
+ th->check = ~tcp_v4_check(skb->len, saddr, daddr, 0);
+ skb->csum_start = skb_transport_header(skb) - skb->head;
+ skb->csum_offset = offsetof(struct tcphdr, check);
+ } else {
+ th->check = tcp_v4_check(skb->len, saddr, daddr,
+ csum_partial(th,
+ th->doff << 2,
+ skb->csum));
+ }
+}
+
+/* This routine computes an IPv4 TCP checksum. */
+void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)
+{
+ const struct inet_sock *inet = inet_sk(sk);
+
+ __tcp_v4_send_check(skb, inet->inet_saddr, inet->inet_daddr);
+}
+EXPORT_SYMBOL(tcp_v4_send_check);
+
+/*
+ * This routine will send an RST to the other tcp.
+ *
+ * Someone asks: why I NEVER use socket parameters (TOS, TTL etc.)
+ * for reset.
+ * Answer: if a packet caused RST, it is not for a socket
+ * existing in our system, if it is matched to a socket,
+ * it is just duplicate segment or bug in other side's TCP.
+ * So that we build reply only basing on parameters
+ * arrived with segment.
+ * Exception: precedence violation. We do not implement it in any case.
+ */
+
+static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
+{
+ const struct tcphdr *th = tcp_hdr(skb);
+ struct {
+ struct tcphdr th;
+#ifdef CONFIG_TCP_MD5SIG
+ __be32 opt[(TCPOLEN_MD5SIG_ALIGNED >> 2)];
+#endif
+ } rep;
+ struct ip_reply_arg arg;
+#ifdef CONFIG_TCP_MD5SIG
+ struct tcp_md5sig_key *key;
+ const __u8 *hash_location = NULL;
+ unsigned char newhash[16];
+ int genhash;
+ struct sock *sk1 = NULL;
+#endif
+ struct net *net;
+
+ /* Never send a reset in response to a reset. */
+ if (th->rst)
+ return;
+
+ /* If sk not NULL, it means we did a successful lookup and incoming
+ * route had to be correct. prequeue might have dropped our dst.
+ */
+ if (!sk && skb_rtable(skb)->rt_type != RTN_LOCAL)
+ return;
+
+ /* Swap the send and the receive. */
+ memset(&rep, 0, sizeof(rep));
+ rep.th.dest = th->source;
+ rep.th.source = th->dest;
+ rep.th.doff = sizeof(struct tcphdr) / 4;
+ rep.th.rst = 1;
+
+ if (th->ack) {
+ rep.th.seq = th->ack_seq;
+ } else {
+ rep.th.ack = 1;
+ rep.th.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
+ skb->len - (th->doff << 2));
+ }
+
+ memset(&arg, 0, sizeof(arg));
+ arg.iov[0].iov_base = (unsigned char *)&rep;
+ arg.iov[0].iov_len = sizeof(rep.th);
+
+ net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
+#ifdef CONFIG_TCP_MD5SIG
+ hash_location = tcp_parse_md5sig_option(th);
+ if (!sk && hash_location) {
+ /*
+ * active side is lost. Try to find listening socket through
+ * source port, and then find md5 key through listening socket.
+ * we are not loose security here:
+ * Incoming packet is checked with md5 hash with finding key,
+ * no RST generated if md5 hash doesn't match.
+ */
+ sk1 = __inet_lookup_listener(net,
+ &tcp_hashinfo, ip_hdr(skb)->saddr,
+ th->source, ip_hdr(skb)->daddr,
+ ntohs(th->source), inet_iif(skb));
+ /* don't send rst if it can't find key */
+ if (!sk1)
+ return;
+ rcu_read_lock();
+ key = tcp_md5_do_lookup(sk1, (union tcp_md5_addr *)
+ &ip_hdr(skb)->saddr, AF_INET);
+ if (!key)
+ goto release_sk1;
+
+ genhash = tcp_v4_md5_hash_skb(newhash, key, NULL, skb);
+ if (genhash || memcmp(hash_location, newhash, 16) != 0)
+ goto release_sk1;
+ } else {
+ key = sk ? tcp_md5_do_lookup(sk, (union tcp_md5_addr *)
+ &ip_hdr(skb)->saddr,
+ AF_INET) : NULL;
+ }
+
+ if (key) {
+ rep.opt[0] = htonl((TCPOPT_NOP << 24) |
+ (TCPOPT_NOP << 16) |
+ (TCPOPT_MD5SIG << 8) |
+ TCPOLEN_MD5SIG);
+ /* Update length and the length the header thinks exists */
+ arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
+ rep.th.doff = arg.iov[0].iov_len / 4;
+
+ tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[1],
+ key, ip_hdr(skb)->saddr,
+ ip_hdr(skb)->daddr, &rep.th);
+ }
+#endif
+ arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
+ ip_hdr(skb)->saddr, /* XXX */
+ arg.iov[0].iov_len, IPPROTO_TCP, 0);
+ arg.csumoffset = offsetof(struct tcphdr, check) / 2;
+ arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0;
+ /* When socket is gone, all binding information is lost.
+ * routing might fail in this case. No choice here, if we choose to force
+ * input interface, we will misroute in case of asymmetric route.
+ */
+ if (sk)
+ arg.bound_dev_if = sk->sk_bound_dev_if;
+
+ arg.tos = ip_hdr(skb)->tos;
+ ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk),
+ skb, &TCP_SKB_CB(skb)->header.h4.opt,
+ ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
+ &arg, arg.iov[0].iov_len);
+
+ TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
+ TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
+
+#ifdef CONFIG_TCP_MD5SIG
+release_sk1:
+ if (sk1) {
+ rcu_read_unlock();
+ sock_put(sk1);
+ }
+#endif
+}
+
+/* The code following below sending ACKs in SYN-RECV and TIME-WAIT states
+ outside socket context is ugly, certainly. What can I do?
+ */
+
+static void tcp_v4_send_ack(struct net *net,
+ struct sk_buff *skb, u32 seq, u32 ack,
+ u32 win, u32 tsval, u32 tsecr, int oif,
+ struct tcp_md5sig_key *key,
+ int reply_flags, u8 tos)
+{
+ const struct tcphdr *th = tcp_hdr(skb);
+ struct {
+ struct tcphdr th;
+ __be32 opt[(TCPOLEN_TSTAMP_ALIGNED >> 2)
+#ifdef CONFIG_TCP_MD5SIG
+ + (TCPOLEN_MD5SIG_ALIGNED >> 2)
+#endif
+ ];
+ } rep;
+ struct ip_reply_arg arg;
+
+ memset(&rep.th, 0, sizeof(struct tcphdr));
+ memset(&arg, 0, sizeof(arg));
+
+ arg.iov[0].iov_base = (unsigned char *)&rep;
+ arg.iov[0].iov_len = sizeof(rep.th);
+ if (tsecr) {
+ rep.opt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
+ (TCPOPT_TIMESTAMP << 8) |
+ TCPOLEN_TIMESTAMP);
+ rep.opt[1] = htonl(tsval);
+ rep.opt[2] = htonl(tsecr);
+ arg.iov[0].iov_len += TCPOLEN_TSTAMP_ALIGNED;
+ }
+
+ /* Swap the send and the receive. */
+ rep.th.dest = th->source;
+ rep.th.source = th->dest;
+ rep.th.doff = arg.iov[0].iov_len / 4;
+ rep.th.seq = htonl(seq);
+ rep.th.ack_seq = htonl(ack);
+ rep.th.ack = 1;
+ rep.th.window = htons(win);
+
+#ifdef CONFIG_TCP_MD5SIG
+ if (key) {
+ int offset = (tsecr) ? 3 : 0;
+
+ rep.opt[offset++] = htonl((TCPOPT_NOP << 24) |
+ (TCPOPT_NOP << 16) |
+ (TCPOPT_MD5SIG << 8) |
+ TCPOLEN_MD5SIG);
+ arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
+ rep.th.doff = arg.iov[0].iov_len/4;
+
+ tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[offset],
+ key, ip_hdr(skb)->saddr,
+ ip_hdr(skb)->daddr, &rep.th);
+ }
+#endif
+ arg.flags = reply_flags;
+ arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
+ ip_hdr(skb)->saddr, /* XXX */
+ arg.iov[0].iov_len, IPPROTO_TCP, 0);
+ arg.csumoffset = offsetof(struct tcphdr, check) / 2;
+ if (oif)
+ arg.bound_dev_if = oif;
+ arg.tos = tos;
+ ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk),
+ skb, &TCP_SKB_CB(skb)->header.h4.opt,
+ ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
+ &arg, arg.iov[0].iov_len);
+
+ TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
+}
+
+static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
+{
+ struct inet_timewait_sock *tw = inet_twsk(sk);
+ struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
+
+ tcp_v4_send_ack(sock_net(sk), skb,
+ tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
+ tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
+ tcp_time_stamp + tcptw->tw_ts_offset,
+ tcptw->tw_ts_recent,
+ tw->tw_bound_dev_if,
+ tcp_twsk_md5_key(tcptw),
+ tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0,
+ tw->tw_tos
+ );
+
+ inet_twsk_put(tw);
+}
+
+static void tcp_v4_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
+ struct request_sock *req)
+{
+ /* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
+ * sk->sk_state == TCP_SYN_RECV -> for Fast Open.
+ */
+ u32 seq = (sk->sk_state == TCP_LISTEN) ? tcp_rsk(req)->snt_isn + 1 :
+ tcp_sk(sk)->snd_nxt;
+
+ /* RFC 7323 2.3
+ * The window field (SEG.WND) of every outgoing segment, with the
+ * exception of <SYN> segments, MUST be right-shifted by
+ * Rcv.Wind.Shift bits:
+ */
+ tcp_v4_send_ack(sock_net(sk), skb, seq,
+ tcp_rsk(req)->rcv_nxt,
+ req->rsk_rcv_wnd >> inet_rsk(req)->rcv_wscale,
+ tcp_time_stamp,
+ req->ts_recent,
+ 0,
+ tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&ip_hdr(skb)->daddr,
+ AF_INET),
+ inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0,
+ ip_hdr(skb)->tos);
+}
+
+/*
+ * Send a SYN-ACK after having received a SYN.
+ * This still operates on a request_sock only, not on a big
+ * socket.
+ */
+static int tcp_v4_send_synack(const struct sock *sk, struct dst_entry *dst,
+ struct flowi *fl,
+ struct request_sock *req,
+ struct tcp_fastopen_cookie *foc,
+ bool attach_req)
+{
+ const struct inet_request_sock *ireq = inet_rsk(req);
+ struct flowi4 fl4;
+ int err = -1;
+ struct sk_buff *skb;
+
+ /* First, grab a route. */
+ if (!dst && (dst = inet_csk_route_req(sk, &fl4, req)) == NULL)
+ return -1;
+
+ skb = tcp_make_synack(sk, dst, req, foc, attach_req);
+
+ if (skb) {
+ __tcp_v4_send_check(skb, ireq->ir_loc_addr, ireq->ir_rmt_addr);
+
+ err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
+ ireq->ir_rmt_addr,
+ ireq_opt_deref(ireq));
+ err = net_xmit_eval(err);
+ }
+
+ return err;
+}
+
+/*
+ * IPv4 request_sock destructor.
+ */
+static void tcp_v4_reqsk_destructor(struct request_sock *req)
+{
+ kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1));
+}
+
+
+#ifdef CONFIG_TCP_MD5SIG
+/*
+ * RFC2385 MD5 checksumming requires a mapping of
+ * IP address->MD5 Key.
+ * We need to maintain these in the sk structure.
+ */
+
+/* Find the Key structure for an address. */
+struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
+ const union tcp_md5_addr *addr,
+ int family)
+{
+ const struct tcp_sock *tp = tcp_sk(sk);
+ struct tcp_md5sig_key *key;
+ unsigned int size = sizeof(struct in_addr);
+ const struct tcp_md5sig_info *md5sig;
+
+ /* caller either holds rcu_read_lock() or socket lock */
+ md5sig = rcu_dereference_check(tp->md5sig_info,
+ sock_owned_by_user(sk) ||
+ lockdep_is_held((spinlock_t *)&sk->sk_lock.slock));
+ if (!md5sig)
+ return NULL;
+#if IS_ENABLED(CONFIG_IPV6)
+ if (family == AF_INET6)
+ size = sizeof(struct in6_addr);
+#endif
+ hlist_for_each_entry_rcu(key, &md5sig->head, node) {
+ if (key->family != family)
+ continue;
+ if (!memcmp(&key->addr, addr, size))
+ return key;
+ }
+ return NULL;
+}
+EXPORT_SYMBOL(tcp_md5_do_lookup);
+
+struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
+ const struct sock *addr_sk)
+{
+ const union tcp_md5_addr *addr;
+
+ addr = (const union tcp_md5_addr *)&addr_sk->sk_daddr;
+ return tcp_md5_do_lookup(sk, addr, AF_INET);
+}
+EXPORT_SYMBOL(tcp_v4_md5_lookup);
+
+/* This can be called on a newly created socket, from other files */
+int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
+ int family, const u8 *newkey, u8 newkeylen, gfp_t gfp)
+{
+ /* Add Key to the list */
+ struct tcp_md5sig_key *key;
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct tcp_md5sig_info *md5sig;
+
+ key = tcp_md5_do_lookup(sk, addr, family);
+ if (key) {
+ /* Pre-existing entry - just update that one. */
+ memcpy(key->key, newkey, newkeylen);
+ key->keylen = newkeylen;
+ return 0;
+ }
+
+ md5sig = rcu_dereference_protected(tp->md5sig_info,
+ sock_owned_by_user(sk) ||
+ lockdep_is_held(&sk->sk_lock.slock));
+ if (!md5sig) {
+ md5sig = kmalloc(sizeof(*md5sig), gfp);
+ if (!md5sig)
+ return -ENOMEM;
+
+ sk_nocaps_add(sk, NETIF_F_GSO_MASK);
+ INIT_HLIST_HEAD(&md5sig->head);
+ rcu_assign_pointer(tp->md5sig_info, md5sig);
+ }
+
+ key = sock_kmalloc(sk, sizeof(*key), gfp);
+ if (!key)
+ return -ENOMEM;
+ if (!tcp_alloc_md5sig_pool()) {
+ sock_kfree_s(sk, key, sizeof(*key));
+ return -ENOMEM;
+ }
+
+ memcpy(key->key, newkey, newkeylen);
+ key->keylen = newkeylen;
+ key->family = family;
+ memcpy(&key->addr, addr,
+ (family == AF_INET6) ? sizeof(struct in6_addr) :
+ sizeof(struct in_addr));
+ hlist_add_head_rcu(&key->node, &md5sig->head);
+ return 0;
+}
+EXPORT_SYMBOL(tcp_md5_do_add);
+
+int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, int family)
+{
+ struct tcp_md5sig_key *key;
+
+ key = tcp_md5_do_lookup(sk, addr, family);
+ if (!key)
+ return -ENOENT;
+ hlist_del_rcu(&key->node);
+ atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
+ kfree_rcu(key, rcu);
+ return 0;
+}
+EXPORT_SYMBOL(tcp_md5_do_del);
+
+static void tcp_clear_md5_list(struct sock *sk)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct tcp_md5sig_key *key;
+ struct hlist_node *n;
+ struct tcp_md5sig_info *md5sig;
+
+ md5sig = rcu_dereference_protected(tp->md5sig_info, 1);
+
+ hlist_for_each_entry_safe(key, n, &md5sig->head, node) {
+ hlist_del_rcu(&key->node);
+ atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
+ kfree_rcu(key, rcu);
+ }
+}
+
+static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
+ int optlen)
+{
+ struct tcp_md5sig cmd;
+ struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr;
+
+ if (optlen < sizeof(cmd))
+ return -EINVAL;
+
+ if (copy_from_user(&cmd, optval, sizeof(cmd)))
+ return -EFAULT;
+
+ if (sin->sin_family != AF_INET)
+ return -EINVAL;
+
+ if (!cmd.tcpm_keylen)
+ return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr,
+ AF_INET);
+
+ if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
+ return -EINVAL;
+
+ return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr,
+ AF_INET, cmd.tcpm_key, cmd.tcpm_keylen,
+ GFP_KERNEL);
+}
+
+static int tcp_v4_md5_hash_pseudoheader(struct tcp_md5sig_pool *hp,
+ __be32 daddr, __be32 saddr, int nbytes)
+{
+ struct tcp4_pseudohdr *bp;
+ struct scatterlist sg;
+
+ bp = &hp->md5_blk.ip4;
+
+ /*
+ * 1. the TCP pseudo-header (in the order: source IP address,
+ * destination IP address, zero-padded protocol number, and
+ * segment length)
+ */
+ bp->saddr = saddr;
+ bp->daddr = daddr;
+ bp->pad = 0;
+ bp->protocol = IPPROTO_TCP;
+ bp->len = cpu_to_be16(nbytes);
+
+ sg_init_one(&sg, bp, sizeof(*bp));
+ return crypto_hash_update(&hp->md5_desc, &sg, sizeof(*bp));
+}
+
+static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
+ __be32 daddr, __be32 saddr, const struct tcphdr *th)
+{
+ struct tcp_md5sig_pool *hp;
+ struct hash_desc *desc;
+
+ hp = tcp_get_md5sig_pool();
+ if (!hp)
+ goto clear_hash_noput;
+ desc = &hp->md5_desc;
+
+ if (crypto_hash_init(desc))
+ goto clear_hash;
+ if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, th->doff << 2))
+ goto clear_hash;
+ if (tcp_md5_hash_header(hp, th))
+ goto clear_hash;
+ if (tcp_md5_hash_key(hp, key))
+ goto clear_hash;
+ if (crypto_hash_final(desc, md5_hash))
+ goto clear_hash;
+
+ tcp_put_md5sig_pool();
+ return 0;
+
+clear_hash:
+ tcp_put_md5sig_pool();
+clear_hash_noput:
+ memset(md5_hash, 0, 16);
+ return 1;
+}
+
+int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
+ const struct sock *sk,
+ const struct sk_buff *skb)
+{
+ struct tcp_md5sig_pool *hp;
+ struct hash_desc *desc;
+ const struct tcphdr *th = tcp_hdr(skb);
+ __be32 saddr, daddr;
+
+ if (sk) { /* valid for establish/request sockets */
+ saddr = sk->sk_rcv_saddr;
+ daddr = sk->sk_daddr;
+ } else {
+ const struct iphdr *iph = ip_hdr(skb);
+ saddr = iph->saddr;
+ daddr = iph->daddr;
+ }
+
+ hp = tcp_get_md5sig_pool();
+ if (!hp)
+ goto clear_hash_noput;
+ desc = &hp->md5_desc;
+
+ if (crypto_hash_init(desc))
+ goto clear_hash;
+
+ if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, skb->len))
+ goto clear_hash;
+ if (tcp_md5_hash_header(hp, th))
+ goto clear_hash;
+ if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2))
+ goto clear_hash;
+ if (tcp_md5_hash_key(hp, key))
+ goto clear_hash;
+ if (crypto_hash_final(desc, md5_hash))
+ goto clear_hash;
+
+ tcp_put_md5sig_pool();
+ return 0;
+
+clear_hash:
+ tcp_put_md5sig_pool();
+clear_hash_noput:
+ memset(md5_hash, 0, 16);
+ return 1;
+}
+EXPORT_SYMBOL(tcp_v4_md5_hash_skb);
+
+#endif
+
+/* Called with rcu_read_lock() */
+static bool tcp_v4_inbound_md5_hash(const struct sock *sk,
+ const struct sk_buff *skb)
+{
+#ifdef CONFIG_TCP_MD5SIG
+ /*
+ * This gets called for each TCP segment that arrives
+ * so we want to be efficient.
+ * We have 3 drop cases:
+ * o No MD5 hash and one expected.
+ * o MD5 hash and we're not expecting one.
+ * o MD5 hash and its wrong.
+ */
+ const __u8 *hash_location = NULL;
+ struct tcp_md5sig_key *hash_expected;
+ const struct iphdr *iph = ip_hdr(skb);
+ const struct tcphdr *th = tcp_hdr(skb);
+ int genhash;
+ unsigned char newhash[16];
+
+ hash_expected = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&iph->saddr,
+ AF_INET);
+ hash_location = tcp_parse_md5sig_option(th);
+
+ /* We've parsed the options - do we have a hash? */
+ if (!hash_expected && !hash_location)
+ return false;
+
+ if (hash_expected && !hash_location) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
+ return true;
+ }
+
+ if (!hash_expected && hash_location) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
+ return true;
+ }
+
+ /* Okay, so this is hash_expected and hash_location -
+ * so we need to calculate the checksum.
+ */
+ genhash = tcp_v4_md5_hash_skb(newhash,
+ hash_expected,
+ NULL, skb);
+
+ if (genhash || memcmp(hash_location, newhash, 16) != 0) {
+ net_info_ratelimited("MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s\n",
+ &iph->saddr, ntohs(th->source),
+ &iph->daddr, ntohs(th->dest),
+ genhash ? " tcp_v4_calc_md5_hash failed"
+ : "");
+ return true;
+ }
+ return false;
+#endif
+ return false;
+}
+
+static void tcp_v4_init_req(struct request_sock *req,
+ const struct sock *sk_listener,
+ struct sk_buff *skb)
+{
+ struct inet_request_sock *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->no_srccheck = inet_sk(sk_listener)->transparent;
+ RCU_INIT_POINTER(ireq->ireq_opt, tcp_v4_save_options(skb));
+}
+
+static struct dst_entry *tcp_v4_route_req(const struct sock *sk,
+ struct flowi *fl,
+ const struct request_sock *req,
+ bool *strict)
+{
+ struct dst_entry *dst = inet_csk_route_req(sk, &fl->u.ip4, req);
+
+ if (strict) {
+ if (fl->u.ip4.daddr == inet_rsk(req)->ir_rmt_addr)
+ *strict = true;
+ else
+ *strict = false;
+ }
+
+ return dst;
+}
+
+struct request_sock_ops tcp_request_sock_ops __read_mostly = {
+ .family = PF_INET,
+ .obj_size = sizeof(struct tcp_request_sock),
+ .rtx_syn_ack = tcp_rtx_synack,
+ .send_ack = tcp_v4_reqsk_send_ack,
+ .destructor = tcp_v4_reqsk_destructor,
+ .send_reset = tcp_v4_send_reset,
+ .syn_ack_timeout = tcp_syn_ack_timeout,
+};
+
+static const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
+ .mss_clamp = TCP_MSS_DEFAULT,
+#ifdef CONFIG_TCP_MD5SIG
+ .req_md5_lookup = tcp_v4_md5_lookup,
+ .calc_md5_hash = tcp_v4_md5_hash_skb,
+#endif
+ .init_req = tcp_v4_init_req,
+#ifdef CONFIG_SYN_COOKIES
+ .cookie_init_seq = cookie_v4_init_sequence,
+#endif
+ .route_req = tcp_v4_route_req,
+ .init_seq = tcp_v4_init_sequence,
+ .send_synack = tcp_v4_send_synack,
+};
+
+int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
+{
+ /* Never answer to SYNs send to broadcast or multicast */
+ if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
+ goto drop;
+
+ return tcp_conn_request(&tcp_request_sock_ops,
+ &tcp_request_sock_ipv4_ops, sk, skb);
+
+drop:
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
+ return 0;
+}
+EXPORT_SYMBOL(tcp_v4_conn_request);
+
+
+/*
+ * The three way handshake has completed - we got a valid synack -
+ * now create the new socket.
+ */
+struct sock *tcp_v4_syn_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 tcp_sock *newtp;
+ struct sock *newsk;
+#ifdef CONFIG_TCP_MD5SIG
+ struct tcp_md5sig_key *key;
+#endif
+ struct ip_options_rcu *inet_opt;
+
+ if (sk_acceptq_is_full(sk))
+ goto exit_overflow;
+
+ newsk = tcp_create_openreq_child(sk, req, skb);
+ if (!newsk)
+ goto exit_nonewsk;
+
+ newsk->sk_gso_type = SKB_GSO_TCPV4;
+ inet_sk_rx_dst_set(newsk, skb);
+
+ newtp = tcp_sk(newsk);
+ 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;
+ inet_opt = rcu_dereference(ireq->ireq_opt);
+ RCU_INIT_POINTER(newinet->inet_opt, inet_opt);
+ newinet->mc_index = inet_iif(skb);
+ newinet->mc_ttl = ip_hdr(skb)->ttl;
+ newinet->rcv_tos = ip_hdr(skb)->tos;
+ inet_csk(newsk)->icsk_ext_hdr_len = 0;
+ if (inet_opt)
+ inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
+ newinet->inet_id = newtp->write_seq ^ jiffies;
+
+ if (!dst) {
+ dst = inet_csk_route_child_sock(sk, newsk, req);
+ if (!dst)
+ goto put_and_exit;
+ } else {
+ /* syncookie case : see end of cookie_v4_check() */
+ }
+ sk_setup_caps(newsk, dst);
+
+ tcp_ca_openreq_child(newsk, dst);
+
+ tcp_sync_mss(newsk, dst_mtu(dst));
+ newtp->advmss = dst_metric_advmss(dst);
+ if (tcp_sk(sk)->rx_opt.user_mss &&
+ tcp_sk(sk)->rx_opt.user_mss < newtp->advmss)
+ newtp->advmss = tcp_sk(sk)->rx_opt.user_mss;
+
+ tcp_initialize_rcv_mss(newsk);
+
+#ifdef CONFIG_TCP_MD5SIG
+ /* Copy over the MD5 key from the original socket */
+ key = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&newinet->inet_daddr,
+ AF_INET);
+ if (key) {
+ /*
+ * We're using one, so create a matching key
+ * on the newsk structure. If we fail to get
+ * memory, then we end up not copying the key
+ * across. Shucks.
+ */
+ tcp_md5_do_add(newsk, (union tcp_md5_addr *)&newinet->inet_daddr,
+ AF_INET, key->key, key->keylen, GFP_ATOMIC);
+ sk_nocaps_add(newsk, NETIF_F_GSO_MASK);
+ }
+#endif
+
+ if (__inet_inherit_port(sk, newsk) < 0)
+ goto put_and_exit;
+ *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash));
+ if (likely(*own_req)) {
+ tcp_move_syn(newtp, req);
+ ireq->ireq_opt = NULL;
+ } else {
+ newinet->inet_opt = NULL;
+ }
+ return newsk;
+
+exit_overflow:
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
+exit_nonewsk:
+ dst_release(dst);
+exit:
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
+ return NULL;
+put_and_exit:
+ newinet->inet_opt = NULL;
+ inet_csk_prepare_forced_close(newsk);
+ tcp_done(newsk);
+ goto exit;
+}
+EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
+
+static struct sock *tcp_v4_cookie_check(struct sock *sk, struct sk_buff *skb)
+{
+#ifdef CONFIG_SYN_COOKIES
+ const struct tcphdr *th = tcp_hdr(skb);
+
+ if (!th->syn)
+ sk = cookie_v4_check(sk, skb);
+#endif
+ return sk;
+}
+
+/* The socket must have it's spinlock held when we get
+ * here, unless it is a TCP_LISTEN socket.
+ *
+ * We have a potential double-lock case here, so even when
+ * doing backlog processing we use the BH locking scheme.
+ * This is because we cannot sleep with the original spinlock
+ * held.
+ */
+int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
+{
+ struct sock *rsk;
+
+ if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
+ struct dst_entry *dst = sk->sk_rx_dst;
+
+ sock_rps_save_rxhash(sk, skb);
+ sk_mark_napi_id(sk, skb);
+ if (dst) {
+ if (inet_sk(sk)->rx_dst_ifindex != skb->skb_iif ||
+ !dst->ops->check(dst, 0)) {
+ dst_release(dst);
+ sk->sk_rx_dst = NULL;
+ }
+ }
+ tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len);
+ return 0;
+ }
+
+ if (tcp_checksum_complete(skb))
+ goto csum_err;
+
+ if (sk->sk_state == TCP_LISTEN) {
+ struct sock *nsk = tcp_v4_cookie_check(sk, skb);
+
+ if (!nsk)
+ goto discard;
+ if (nsk != sk) {
+ sock_rps_save_rxhash(nsk, skb);
+ sk_mark_napi_id(nsk, skb);
+ if (tcp_child_process(sk, nsk, skb)) {
+ rsk = nsk;
+ goto reset;
+ }
+ return 0;
+ }
+ } else
+ sock_rps_save_rxhash(sk, skb);
+
+ if (tcp_rcv_state_process(sk, skb)) {
+ rsk = sk;
+ goto reset;
+ }
+ return 0;
+
+reset:
+ tcp_v4_send_reset(rsk, skb);
+discard:
+ kfree_skb(skb);
+ /* Be careful here. If this function gets more complicated and
+ * gcc suffers from register pressure on the x86, sk (in %ebx)
+ * might be destroyed here. This current version compiles correctly,
+ * but you have been warned.
+ */
+ return 0;
+
+csum_err:
+ TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_CSUMERRORS);
+ TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
+ goto discard;
+}
+EXPORT_SYMBOL(tcp_v4_do_rcv);
+
+void tcp_v4_early_demux(struct sk_buff *skb)
+{
+ const struct iphdr *iph;
+ const struct tcphdr *th;
+ struct sock *sk;
+
+ if (skb->pkt_type != PACKET_HOST)
+ return;
+
+ if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct tcphdr)))
+ return;
+
+ iph = ip_hdr(skb);
+ th = tcp_hdr(skb);
+
+ if (th->doff < sizeof(struct tcphdr) / 4)
+ return;
+
+ sk = __inet_lookup_established(dev_net(skb->dev), &tcp_hashinfo,
+ iph->saddr, th->source,
+ iph->daddr, ntohs(th->dest),
+ skb->skb_iif);
+ if (sk) {
+ skb->sk = sk;
+ skb->destructor = sock_edemux;
+ if (sk_fullsock(sk)) {
+ struct dst_entry *dst = READ_ONCE(sk->sk_rx_dst);
+
+ if (dst)
+ dst = dst_check(dst, 0);
+ if (dst &&
+ inet_sk(sk)->rx_dst_ifindex == skb->skb_iif)
+ skb_dst_set_noref(skb, dst);
+ }
+ }
+}
+
+/* Packet is added to VJ-style prequeue for processing in process
+ * context, if a reader task is waiting. Apparently, this exciting
+ * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
+ * failed somewhere. Latency? Burstiness? Well, at least now we will
+ * see, why it failed. 8)8) --ANK
+ *
+ */
+bool tcp_prequeue(struct sock *sk, struct sk_buff *skb)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+
+ if (sysctl_tcp_low_latency || !tp->ucopy.task)
+ return false;
+
+ if (skb->len <= tcp_hdrlen(skb) &&
+ skb_queue_len(&tp->ucopy.prequeue) == 0)
+ return false;
+
+ /* Before escaping RCU protected region, we need to take care of skb
+ * dst. Prequeue is only enabled for established sockets.
+ * For such sockets, we might need the skb dst only to set sk->sk_rx_dst
+ * Instead of doing full sk_rx_dst validity here, let's perform
+ * an optimistic check.
+ */
+ if (likely(sk->sk_rx_dst))
+ skb_dst_drop(skb);
+ else
+ skb_dst_force_safe(skb);
+
+ __skb_queue_tail(&tp->ucopy.prequeue, skb);
+ tp->ucopy.memory += skb->truesize;
+ if (tp->ucopy.memory > sk->sk_rcvbuf) {
+ struct sk_buff *skb1;
+
+ BUG_ON(sock_owned_by_user(sk));
+
+ while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
+ sk_backlog_rcv(sk, skb1);
+ NET_INC_STATS_BH(sock_net(sk),
+ LINUX_MIB_TCPPREQUEUEDROPPED);
+ }
+
+ tp->ucopy.memory = 0;
+ } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
+ wake_up_interruptible_sync_poll(sk_sleep(sk),
+ POLLIN | POLLRDNORM | POLLRDBAND);
+ if (!inet_csk_ack_scheduled(sk))
+ inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
+ (3 * tcp_rto_min(sk)) / 4,
+ TCP_RTO_MAX);
+ }
+ return true;
+}
+EXPORT_SYMBOL(tcp_prequeue);
+
+int tcp_filter(struct sock *sk, struct sk_buff *skb)
+{
+ struct tcphdr *th = (struct tcphdr *)skb->data;
+ unsigned int eaten = skb->len;
+ int err;
+
+ err = sk_filter_trim_cap(sk, skb, th->doff * 4);
+ if (!err) {
+ eaten -= skb->len;
+ TCP_SKB_CB(skb)->end_seq -= eaten;
+ }
+ return err;
+}
+EXPORT_SYMBOL(tcp_filter);
+
+/*
+ * From tcp_input.c
+ */
+
+int tcp_v4_rcv(struct sk_buff *skb)
+{
+ const struct iphdr *iph;
+ const struct tcphdr *th;
+ struct sock *sk;
+ int ret;
+ struct net *net = dev_net(skb->dev);
+
+ if (skb->pkt_type != PACKET_HOST)
+ goto discard_it;
+
+ /* Count it even if it's bad */
+ TCP_INC_STATS_BH(net, TCP_MIB_INSEGS);
+
+ if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
+ goto discard_it;
+
+ th = tcp_hdr(skb);
+
+ if (th->doff < sizeof(struct tcphdr) / 4)
+ goto bad_packet;
+ if (!pskb_may_pull(skb, th->doff * 4))
+ goto discard_it;
+
+ /* An explanation is required here, I think.
+ * Packet length and doff are validated by header prediction,
+ * provided case of th->doff==0 is eliminated.
+ * So, we defer the checks. */
+
+ if (skb_checksum_init(skb, IPPROTO_TCP, inet_compute_pseudo))
+ goto csum_error;
+
+ th = tcp_hdr(skb);
+ iph = ip_hdr(skb);
+ /* This is tricky : We move IPCB at its correct location into TCP_SKB_CB()
+ * barrier() makes sure compiler wont play fool^Waliasing games.
+ */
+ memmove(&TCP_SKB_CB(skb)->header.h4, IPCB(skb),
+ sizeof(struct inet_skb_parm));
+ barrier();
+
+ TCP_SKB_CB(skb)->seq = ntohl(th->seq);
+ TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
+ skb->len - th->doff * 4);
+ TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
+ TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th);
+ TCP_SKB_CB(skb)->tcp_tw_isn = 0;
+ TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph);
+ TCP_SKB_CB(skb)->sacked = 0;
+
+lookup:
+ sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
+ if (!sk)
+ goto no_tcp_socket;
+
+process:
+ if (sk->sk_state == TCP_TIME_WAIT)
+ goto do_time_wait;
+
+ if (sk->sk_state == TCP_NEW_SYN_RECV) {
+ struct request_sock *req = inet_reqsk(sk);
+ struct sock *nsk;
+
+ sk = req->rsk_listener;
+ if (unlikely(tcp_v4_inbound_md5_hash(sk, skb))) {
+ reqsk_put(req);
+ goto discard_it;
+ }
+ if (unlikely(sk->sk_state != TCP_LISTEN)) {
+ inet_csk_reqsk_queue_drop_and_put(sk, req);
+ goto lookup;
+ }
+ sock_hold(sk);
+ nsk = tcp_check_req(sk, skb, req, false);
+ if (!nsk) {
+ reqsk_put(req);
+ goto discard_and_relse;
+ }
+ if (nsk == sk) {
+ reqsk_put(req);
+ } else if (tcp_child_process(sk, nsk, skb)) {
+ tcp_v4_send_reset(nsk, skb);
+ goto discard_and_relse;
+ } else {
+ sock_put(sk);
+ return 0;
+ }
+ }
+ if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
+ NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
+ goto discard_and_relse;
+ }
+
+ if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
+ goto discard_and_relse;
+
+ if (tcp_v4_inbound_md5_hash(sk, skb))
+ goto discard_and_relse;
+
+ nf_reset(skb);
+
+ if (tcp_filter(sk, skb))
+ goto discard_and_relse;
+ th = (const struct tcphdr *)skb->data;
+ iph = ip_hdr(skb);
+
+ skb->dev = NULL;
+
+ if (sk->sk_state == TCP_LISTEN) {
+ ret = tcp_v4_do_rcv(sk, skb);
+ goto put_and_return;
+ }
+
+ sk_incoming_cpu_update(sk);
+
+ bh_lock_sock_nested(sk);
+ tcp_sk(sk)->segs_in += max_t(u16, 1, skb_shinfo(skb)->gso_segs);
+ ret = 0;
+ if (!sock_owned_by_user(sk)) {
+ if (!tcp_prequeue(sk, skb))
+ ret = tcp_v4_do_rcv(sk, skb);
+ } else if (unlikely(sk_add_backlog(sk, skb,
+ sk->sk_rcvbuf + sk->sk_sndbuf))) {
+ bh_unlock_sock(sk);
+ NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
+ goto discard_and_relse;
+ }
+ bh_unlock_sock(sk);
+
+put_and_return:
+ sock_put(sk);
+
+ return ret;
+
+no_tcp_socket:
+ if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
+ goto discard_it;
+
+ if (tcp_checksum_complete(skb)) {
+csum_error:
+ TCP_INC_STATS_BH(net, TCP_MIB_CSUMERRORS);
+bad_packet:
+ TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
+ } else {
+ tcp_v4_send_reset(NULL, skb);
+ }
+
+discard_it:
+ /* Discard frame. */
+ kfree_skb(skb);
+ return 0;
+
+discard_and_relse:
+ sock_put(sk);
+ goto discard_it;
+
+do_time_wait:
+ if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
+ inet_twsk_put(inet_twsk(sk));
+ goto discard_it;
+ }
+
+ if (tcp_checksum_complete(skb)) {
+ inet_twsk_put(inet_twsk(sk));
+ goto csum_error;
+ }
+ switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
+ case TCP_TW_SYN: {
+ struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev),
+ &tcp_hashinfo,
+ iph->saddr, th->source,
+ iph->daddr, th->dest,
+ inet_iif(skb));
+ if (sk2) {
+ inet_twsk_deschedule_put(inet_twsk(sk));
+ sk = sk2;
+ goto process;
+ }
+ /* Fall through to ACK */
+ }
+ case TCP_TW_ACK:
+ tcp_v4_timewait_ack(sk, skb);
+ break;
+ case TCP_TW_RST:
+ goto no_tcp_socket;
+ case TCP_TW_SUCCESS:;
+ }
+ goto discard_it;
+}
+
+static struct timewait_sock_ops tcp_timewait_sock_ops = {
+ .twsk_obj_size = sizeof(struct tcp_timewait_sock),
+ .twsk_unique = tcp_twsk_unique,
+ .twsk_destructor= tcp_twsk_destructor,
+};
+
+void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
+{
+ struct dst_entry *dst = skb_dst(skb);
+
+ if (dst && dst_hold_safe(dst)) {
+ sk->sk_rx_dst = dst;
+ inet_sk(sk)->rx_dst_ifindex = skb->skb_iif;
+ }
+}
+EXPORT_SYMBOL(inet_sk_rx_dst_set);
+
+const struct inet_connection_sock_af_ops ipv4_specific = {
+ .queue_xmit = ip_queue_xmit,
+ .send_check = tcp_v4_send_check,
+ .rebuild_header = inet_sk_rebuild_header,
+ .sk_rx_dst_set = inet_sk_rx_dst_set,
+ .conn_request = tcp_v4_conn_request,
+ .syn_recv_sock = tcp_v4_syn_recv_sock,
+ .net_header_len = sizeof(struct iphdr),
+ .setsockopt = ip_setsockopt,
+ .getsockopt = ip_getsockopt,
+ .addr2sockaddr = inet_csk_addr2sockaddr,
+ .sockaddr_len = sizeof(struct sockaddr_in),
+ .bind_conflict = inet_csk_bind_conflict,
+#ifdef CONFIG_COMPAT
+ .compat_setsockopt = compat_ip_setsockopt,
+ .compat_getsockopt = compat_ip_getsockopt,
+#endif
+ .mtu_reduced = tcp_v4_mtu_reduced,
+};
+EXPORT_SYMBOL(ipv4_specific);
+
+#ifdef CONFIG_TCP_MD5SIG
+static const struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
+ .md5_lookup = tcp_v4_md5_lookup,
+ .calc_md5_hash = tcp_v4_md5_hash_skb,
+ .md5_parse = tcp_v4_parse_md5_keys,
+};
+#endif
+
+/* NOTE: A lot of things set to zero explicitly by call to
+ * sk_alloc() so need not be done here.
+ */
+static int tcp_v4_init_sock(struct sock *sk)
+{
+ struct inet_connection_sock *icsk = inet_csk(sk);
+
+ tcp_init_sock(sk);
+
+ icsk->icsk_af_ops = &ipv4_specific;
+
+#ifdef CONFIG_TCP_MD5SIG
+ tcp_sk(sk)->af_specific = &tcp_sock_ipv4_specific;
+#endif
+
+ return 0;
+}
+
+void tcp_v4_destroy_sock(struct sock *sk)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+
+ tcp_clear_xmit_timers(sk);
+
+ tcp_cleanup_congestion_control(sk);
+
+ /* Cleanup up the write buffer. */
+ tcp_write_queue_purge(sk);
+
+ /* Cleans up our, hopefully empty, out_of_order_queue. */
+ __skb_queue_purge(&tp->out_of_order_queue);
+
+#ifdef CONFIG_TCP_MD5SIG
+ /* Clean up the MD5 key list, if any */
+ if (tp->md5sig_info) {
+ tcp_clear_md5_list(sk);
+ kfree_rcu(tp->md5sig_info, rcu);
+ tp->md5sig_info = NULL;
+ }
+#endif
+
+ /* Clean prequeue, it must be empty really */
+ __skb_queue_purge(&tp->ucopy.prequeue);
+
+ /* Clean up a referenced TCP bind bucket. */
+ if (inet_csk(sk)->icsk_bind_hash)
+ inet_put_port(sk);
+
+ BUG_ON(tp->fastopen_rsk);
+
+ /* If socket is aborted during connect operation */
+ tcp_free_fastopen_req(tp);
+ tcp_saved_syn_free(tp);
+
+ sk_sockets_allocated_dec(sk);
+ sock_release_memcg(sk);
+}
+EXPORT_SYMBOL(tcp_v4_destroy_sock);
+
+#ifdef CONFIG_PROC_FS
+/* Proc filesystem TCP sock list dumping. */
+
+/*
+ * Get next listener socket follow cur. If cur is NULL, get first socket
+ * starting from bucket given in st->bucket; when st->bucket is zero the
+ * very first socket in the hash table is returned.
+ */
+static void *listening_get_next(struct seq_file *seq, void *cur)
+{
+ struct inet_connection_sock *icsk;
+ struct hlist_nulls_node *node;
+ struct sock *sk = cur;
+ struct inet_listen_hashbucket *ilb;
+ struct tcp_iter_state *st = seq->private;
+ struct net *net = seq_file_net(seq);
+
+ if (!sk) {
+ ilb = &tcp_hashinfo.listening_hash[st->bucket];
+ spin_lock_bh(&ilb->lock);
+ sk = sk_nulls_head(&ilb->head);
+ st->offset = 0;
+ goto get_sk;
+ }
+ ilb = &tcp_hashinfo.listening_hash[st->bucket];
+ ++st->num;
+ ++st->offset;
+
+ sk = sk_nulls_next(sk);
+get_sk:
+ sk_nulls_for_each_from(sk, node) {
+ if (!net_eq(sock_net(sk), net))
+ continue;
+ if (sk->sk_family == st->family) {
+ cur = sk;
+ goto out;
+ }
+ icsk = inet_csk(sk);
+ }
+ spin_unlock_bh(&ilb->lock);
+ st->offset = 0;
+ if (++st->bucket < INET_LHTABLE_SIZE) {
+ ilb = &tcp_hashinfo.listening_hash[st->bucket];
+ spin_lock_bh(&ilb->lock);
+ sk = sk_nulls_head(&ilb->head);
+ goto get_sk;
+ }
+ cur = NULL;
+out:
+ return cur;
+}
+
+static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
+{
+ struct tcp_iter_state *st = seq->private;
+ void *rc;
+
+ st->bucket = 0;
+ st->offset = 0;
+ rc = listening_get_next(seq, NULL);
+
+ while (rc && *pos) {
+ rc = listening_get_next(seq, rc);
+ --*pos;
+ }
+ return rc;
+}
+
+static inline bool empty_bucket(const struct tcp_iter_state *st)
+{
+ return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain);
+}
+
+/*
+ * Get first established socket starting from bucket given in st->bucket.
+ * If st->bucket is zero, the very first socket in the hash is returned.
+ */
+static void *established_get_first(struct seq_file *seq)
+{
+ struct tcp_iter_state *st = seq->private;
+ struct net *net = seq_file_net(seq);
+ void *rc = NULL;
+
+ st->offset = 0;
+ for (; st->bucket <= tcp_hashinfo.ehash_mask; ++st->bucket) {
+ struct sock *sk;
+ struct hlist_nulls_node *node;
+ spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
+
+ /* Lockless fast path for the common case of empty buckets */
+ if (empty_bucket(st))
+ continue;
+
+ spin_lock_bh(lock);
+ sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
+ if (sk->sk_family != st->family ||
+ !net_eq(sock_net(sk), net)) {
+ continue;
+ }
+ rc = sk;
+ goto out;
+ }
+ spin_unlock_bh(lock);
+ }
+out:
+ return rc;
+}
+
+static void *established_get_next(struct seq_file *seq, void *cur)
+{
+ struct sock *sk = cur;
+ struct hlist_nulls_node *node;
+ struct tcp_iter_state *st = seq->private;
+ struct net *net = seq_file_net(seq);
+
+ ++st->num;
+ ++st->offset;
+
+ sk = sk_nulls_next(sk);
+
+ sk_nulls_for_each_from(sk, node) {
+ if (sk->sk_family == st->family && net_eq(sock_net(sk), net))
+ return sk;
+ }
+
+ spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
+ ++st->bucket;
+ return established_get_first(seq);
+}
+
+static void *established_get_idx(struct seq_file *seq, loff_t pos)
+{
+ struct tcp_iter_state *st = seq->private;
+ void *rc;
+
+ st->bucket = 0;
+ rc = established_get_first(seq);
+
+ while (rc && pos) {
+ rc = established_get_next(seq, rc);
+ --pos;
+ }
+ return rc;
+}
+
+static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
+{
+ void *rc;
+ struct tcp_iter_state *st = seq->private;
+
+ st->state = TCP_SEQ_STATE_LISTENING;
+ rc = listening_get_idx(seq, &pos);
+
+ if (!rc) {
+ st->state = TCP_SEQ_STATE_ESTABLISHED;
+ rc = established_get_idx(seq, pos);
+ }
+
+ return rc;
+}
+
+static void *tcp_seek_last_pos(struct seq_file *seq)
+{
+ struct tcp_iter_state *st = seq->private;
+ int offset = st->offset;
+ int orig_num = st->num;
+ void *rc = NULL;
+
+ switch (st->state) {
+ case TCP_SEQ_STATE_LISTENING:
+ if (st->bucket >= INET_LHTABLE_SIZE)
+ break;
+ st->state = TCP_SEQ_STATE_LISTENING;
+ rc = listening_get_next(seq, NULL);
+ while (offset-- && rc)
+ rc = listening_get_next(seq, rc);
+ if (rc)
+ break;
+ st->bucket = 0;
+ st->state = TCP_SEQ_STATE_ESTABLISHED;
+ /* Fallthrough */
+ case TCP_SEQ_STATE_ESTABLISHED:
+ if (st->bucket > tcp_hashinfo.ehash_mask)
+ break;
+ rc = established_get_first(seq);
+ while (offset-- && rc)
+ rc = established_get_next(seq, rc);
+ }
+
+ st->num = orig_num;
+
+ return rc;
+}
+
+static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
+{
+ struct tcp_iter_state *st = seq->private;
+ void *rc;
+
+ if (*pos && *pos == st->last_pos) {
+ rc = tcp_seek_last_pos(seq);
+ if (rc)
+ goto out;
+ }
+
+ st->state = TCP_SEQ_STATE_LISTENING;
+ st->num = 0;
+ st->bucket = 0;
+ st->offset = 0;
+ rc = *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
+
+out:
+ st->last_pos = *pos;
+ return rc;
+}
+
+static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+ struct tcp_iter_state *st = seq->private;
+ void *rc = NULL;
+
+ if (v == SEQ_START_TOKEN) {
+ rc = tcp_get_idx(seq, 0);
+ goto out;
+ }
+
+ switch (st->state) {
+ case TCP_SEQ_STATE_LISTENING:
+ rc = listening_get_next(seq, v);
+ if (!rc) {
+ st->state = TCP_SEQ_STATE_ESTABLISHED;
+ st->bucket = 0;
+ st->offset = 0;
+ rc = established_get_first(seq);
+ }
+ break;
+ case TCP_SEQ_STATE_ESTABLISHED:
+ rc = established_get_next(seq, v);
+ break;
+ }
+out:
+ ++*pos;
+ st->last_pos = *pos;
+ return rc;
+}
+
+static void tcp_seq_stop(struct seq_file *seq, void *v)
+{
+ struct tcp_iter_state *st = seq->private;
+
+ switch (st->state) {
+ case TCP_SEQ_STATE_LISTENING:
+ if (v != SEQ_START_TOKEN)
+ spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock);
+ break;
+ case TCP_SEQ_STATE_ESTABLISHED:
+ if (v)
+ spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
+ break;
+ }
+}
+
+int tcp_seq_open(struct inode *inode, struct file *file)
+{
+ struct tcp_seq_afinfo *afinfo = PDE_DATA(inode);
+ struct tcp_iter_state *s;
+ int err;
+
+ err = seq_open_net(inode, file, &afinfo->seq_ops,
+ sizeof(struct tcp_iter_state));
+ if (err < 0)
+ return err;
+
+ s = ((struct seq_file *)file->private_data)->private;
+ s->family = afinfo->family;
+ s->last_pos = 0;
+ return 0;
+}
+EXPORT_SYMBOL(tcp_seq_open);
+
+int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo)
+{
+ int rc = 0;
+ struct proc_dir_entry *p;
+
+ afinfo->seq_ops.start = tcp_seq_start;
+ afinfo->seq_ops.next = tcp_seq_next;
+ afinfo->seq_ops.stop = tcp_seq_stop;
+
+ p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net,
+ afinfo->seq_fops, afinfo);
+ if (!p)
+ rc = -ENOMEM;
+ return rc;
+}
+EXPORT_SYMBOL(tcp_proc_register);
+
+void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
+{
+ remove_proc_entry(afinfo->name, net->proc_net);
+}
+EXPORT_SYMBOL(tcp_proc_unregister);
+
+static void get_openreq4(const struct request_sock *req,
+ struct seq_file *f, int i)
+{
+ const struct inet_request_sock *ireq = inet_rsk(req);
+ long delta = req->rsk_timer.expires - jiffies;
+
+ seq_printf(f, "%4d: %08X:%04X %08X:%04X"
+ " %02X %08X:%08X %02X:%08lX %08X %5u %8d %u %d %pK",
+ i,
+ ireq->ir_loc_addr,
+ ireq->ir_num,
+ ireq->ir_rmt_addr,
+ ntohs(ireq->ir_rmt_port),
+ TCP_SYN_RECV,
+ 0, 0, /* could print option size, but that is af dependent. */
+ 1, /* timers active (only the expire timer) */
+ jiffies_delta_to_clock_t(delta),
+ req->num_timeout,
+ from_kuid_munged(seq_user_ns(f),
+ sock_i_uid(req->rsk_listener)),
+ 0, /* non standard timer */
+ 0, /* open_requests have no inode */
+ 0,
+ req);
+}
+
+static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i)
+{
+ int timer_active;
+ unsigned long timer_expires;
+ const struct tcp_sock *tp = tcp_sk(sk);
+ const struct inet_connection_sock *icsk = inet_csk(sk);
+ const struct inet_sock *inet = inet_sk(sk);
+ const struct fastopen_queue *fastopenq = &icsk->icsk_accept_queue.fastopenq;
+ __be32 dest = inet->inet_daddr;
+ __be32 src = inet->inet_rcv_saddr;
+ __u16 destp = ntohs(inet->inet_dport);
+ __u16 srcp = ntohs(inet->inet_sport);
+ int rx_queue;
+ int state;
+
+ if (icsk->icsk_pending == ICSK_TIME_RETRANS ||
+ icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS ||
+ icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) {
+ timer_active = 1;
+ timer_expires = icsk->icsk_timeout;
+ } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
+ timer_active = 4;
+ timer_expires = icsk->icsk_timeout;
+ } else if (timer_pending(&sk->sk_timer)) {
+ timer_active = 2;
+ timer_expires = sk->sk_timer.expires;
+ } else {
+ timer_active = 0;
+ timer_expires = jiffies;
+ }
+
+ state = sk_state_load(sk);
+ if (state == TCP_LISTEN)
+ rx_queue = sk->sk_ack_backlog;
+ else
+ /* Because we don't lock the socket,
+ * we might find a transient negative value.
+ */
+ rx_queue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0);
+
+ seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
+ "%08X %5u %8d %lu %d %pK %lu %lu %u %u %d",
+ i, src, srcp, dest, destp, state,
+ tp->write_seq - tp->snd_una,
+ rx_queue,
+ timer_active,
+ jiffies_delta_to_clock_t(timer_expires - jiffies),
+ icsk->icsk_retransmits,
+ from_kuid_munged(seq_user_ns(f), sock_i_uid(sk)),
+ icsk->icsk_probes_out,
+ sock_i_ino(sk),
+ atomic_read(&sk->sk_refcnt), sk,
+ jiffies_to_clock_t(icsk->icsk_rto),
+ jiffies_to_clock_t(icsk->icsk_ack.ato),
+ (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
+ tp->snd_cwnd,
+ state == TCP_LISTEN ?
+ fastopenq->max_qlen :
+ (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh));
+}
+
+static void get_timewait4_sock(const struct inet_timewait_sock *tw,
+ struct seq_file *f, int i)
+{
+ long delta = tw->tw_timer.expires - jiffies;
+ __be32 dest, src;
+ __u16 destp, srcp;
+
+ dest = tw->tw_daddr;
+ src = tw->tw_rcv_saddr;
+ destp = ntohs(tw->tw_dport);
+ srcp = ntohs(tw->tw_sport);
+
+ seq_printf(f, "%4d: %08X:%04X %08X:%04X"
+ " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK",
+ i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
+ 3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
+ atomic_read(&tw->tw_refcnt), tw);
+}
+
+#define TMPSZ 150
+
+static int tcp4_seq_show(struct seq_file *seq, void *v)
+{
+ struct tcp_iter_state *st;
+ struct sock *sk = v;
+
+ seq_setwidth(seq, TMPSZ - 1);
+ if (v == SEQ_START_TOKEN) {
+ seq_puts(seq, " sl local_address rem_address st tx_queue "
+ "rx_queue tr tm->when retrnsmt uid timeout "
+ "inode");
+ goto out;
+ }
+ st = seq->private;
+
+ if (sk->sk_state == TCP_TIME_WAIT)
+ get_timewait4_sock(v, seq, st->num);
+ else if (sk->sk_state == TCP_NEW_SYN_RECV)
+ get_openreq4(v, seq, st->num);
+ else
+ get_tcp4_sock(v, seq, st->num);
+out:
+ seq_pad(seq, '\n');
+ return 0;
+}
+
+static const struct file_operations tcp_afinfo_seq_fops = {
+ .owner = THIS_MODULE,
+ .open = tcp_seq_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release_net
+};
+
+static struct tcp_seq_afinfo tcp4_seq_afinfo = {
+ .name = "tcp",
+ .family = AF_INET,
+ .seq_fops = &tcp_afinfo_seq_fops,
+ .seq_ops = {
+ .show = tcp4_seq_show,
+ },
+};
+
+static int __net_init tcp4_proc_init_net(struct net *net)
+{
+ return tcp_proc_register(net, &tcp4_seq_afinfo);
+}
+
+static void __net_exit tcp4_proc_exit_net(struct net *net)
+{
+ tcp_proc_unregister(net, &tcp4_seq_afinfo);
+}
+
+static struct pernet_operations tcp4_net_ops = {
+ .init = tcp4_proc_init_net,
+ .exit = tcp4_proc_exit_net,
+};
+
+int __init tcp4_proc_init(void)
+{
+ return register_pernet_subsys(&tcp4_net_ops);
+}
+
+void tcp4_proc_exit(void)
+{
+ unregister_pernet_subsys(&tcp4_net_ops);
+}
+#endif /* CONFIG_PROC_FS */
+
+struct proto tcp_prot = {
+ .name = "TCP",
+ .owner = THIS_MODULE,
+ .close = tcp_close,
+ .connect = tcp_v4_connect,
+ .disconnect = tcp_disconnect,
+ .accept = inet_csk_accept,
+ .ioctl = tcp_ioctl,
+ .init = tcp_v4_init_sock,
+ .destroy = tcp_v4_destroy_sock,
+ .shutdown = tcp_shutdown,
+ .setsockopt = tcp_setsockopt,
+ .getsockopt = tcp_getsockopt,
+ .recvmsg = tcp_recvmsg,
+ .sendmsg = tcp_sendmsg,
+ .sendpage = tcp_sendpage,
+ .backlog_rcv = tcp_v4_do_rcv,
+ .release_cb = tcp_release_cb,
+ .hash = inet_hash,
+ .unhash = inet_unhash,
+ .get_port = inet_csk_get_port,
+ .enter_memory_pressure = tcp_enter_memory_pressure,
+ .stream_memory_free = tcp_stream_memory_free,
+ .sockets_allocated = &tcp_sockets_allocated,
+ .orphan_count = &tcp_orphan_count,
+ .memory_allocated = &tcp_memory_allocated,
+ .memory_pressure = &tcp_memory_pressure,
+ .sysctl_mem = sysctl_tcp_mem,
+ .sysctl_wmem = sysctl_tcp_wmem,
+ .sysctl_rmem = sysctl_tcp_rmem,
+ .max_header = MAX_TCP_HEADER,
+ .obj_size = sizeof(struct tcp_sock),
+ .slab_flags = SLAB_DESTROY_BY_RCU,
+ .twsk_prot = &tcp_timewait_sock_ops,
+ .rsk_prot = &tcp_request_sock_ops,
+ .h.hashinfo = &tcp_hashinfo,
+ .no_autobind = true,
+#ifdef CONFIG_COMPAT
+ .compat_setsockopt = compat_tcp_setsockopt,
+ .compat_getsockopt = compat_tcp_getsockopt,
+#endif
+#ifdef CONFIG_MEMCG_KMEM
+ .init_cgroup = tcp_init_cgroup,
+ .destroy_cgroup = tcp_destroy_cgroup,
+ .proto_cgroup = tcp_proto_cgroup,
+#endif
+};
+EXPORT_SYMBOL(tcp_prot);
+
+static void __net_exit tcp_sk_exit(struct net *net)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu)
+ inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.tcp_sk, cpu));
+ free_percpu(net->ipv4.tcp_sk);
+}
+
+static int __net_init tcp_sk_init(struct net *net)
+{
+ int res, cpu;
+
+ net->ipv4.tcp_sk = alloc_percpu(struct sock *);
+ if (!net->ipv4.tcp_sk)
+ return -ENOMEM;
+
+ for_each_possible_cpu(cpu) {
+ struct sock *sk;
+
+ res = inet_ctl_sock_create(&sk, PF_INET, SOCK_RAW,
+ IPPROTO_TCP, net);
+ if (res)
+ goto fail;
+ *per_cpu_ptr(net->ipv4.tcp_sk, cpu) = sk;
+ }
+
+ net->ipv4.sysctl_tcp_ecn = 2;
+ net->ipv4.sysctl_tcp_ecn_fallback = 1;
+
+ net->ipv4.sysctl_tcp_base_mss = TCP_BASE_MSS;
+ net->ipv4.sysctl_tcp_probe_threshold = TCP_PROBE_THRESHOLD;
+ net->ipv4.sysctl_tcp_probe_interval = TCP_PROBE_INTERVAL;
+
+ return 0;
+fail:
+ tcp_sk_exit(net);
+
+ return res;
+}
+
+static void __net_exit tcp_sk_exit_batch(struct list_head *net_exit_list)
+{
+ inet_twsk_purge(&tcp_hashinfo, &tcp_death_row, AF_INET);
+}
+
+static struct pernet_operations __net_initdata tcp_sk_ops = {
+ .init = tcp_sk_init,
+ .exit = tcp_sk_exit,
+ .exit_batch = tcp_sk_exit_batch,
+};
+
+void __init tcp_v4_init(void)
+{
+ inet_hashinfo_init(&tcp_hashinfo);
+ if (register_pernet_subsys(&tcp_sk_ops))
+ panic("Failed to create the TCP control socket.\n");
+}