tcp: do not drop syn_recv on all icmp reports

Petr Novopashenniy reported that ICMP redirects on SYN_RECV sockets
were leading to RST.

This is of course incorrect.

A specific list of ICMP messages should be able to drop a SYN_RECV.

For instance, a REDIRECT on SYN_RECV shall be ignored, as we do
not hold a dst per SYN_RECV pseudo request.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=111751
Fixes: 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table")
Reported-by: Petr Novopashenniy <pety@rusnet.ru>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/tcp.h b/include/net/tcp.h
index f6f8f03..ae6468f 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -447,7 +447,7 @@ const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
 
 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
 void tcp_v4_mtu_reduced(struct sock *sk);
-void tcp_req_err(struct sock *sk, u32 seq);
+void tcp_req_err(struct sock *sk, u32 seq, bool abort);
 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
 struct sock *tcp_create_openreq_child(const struct sock *sk,
                                      struct request_sock *req,

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index a4d5237..7f6ff03 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -311,7 +311,7 @@ static void do_redirect(struct sk_buff *skb, struct sock *sk)
 
 
 /* handle ICMP messages on TCP_NEW_SYN_RECV request sockets */
-void tcp_req_err(struct sock *sk, u32 seq)
+void tcp_req_err(struct sock *sk, u32 seq, bool abort)
 {
        struct request_sock *req = inet_reqsk(sk);
        struct net *net = sock_net(sk);
@@ -323,7 +323,7 @@ void tcp_req_err(struct sock *sk, u32 seq)
 
        if (seq != tcp_rsk(req)->snt_isn) {
                NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
-       } else {
+       } else if (abort) {
                /*
                 * Still in SYN_RECV, just remove it silently.
                 * There is no good way to pass the error to the newly
@@ -383,7 +383,12 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
        }
        seq = ntohl(th->seq);
        if (sk->sk_state == TCP_NEW_SYN_RECV)
-               return tcp_req_err(sk, seq);
+               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

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 006396e..1a5a70f 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -327,6 +327,7 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
        struct tcp_sock *tp;
        __u32 seq, snd_una;
        struct sock *sk;
+       bool fatal;
        int err;
 
        sk = __inet6_lookup_established(net, &tcp_hashinfo,
@@ -345,8 +346,9 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
                return;
        }
        seq = ntohl(th->seq);
+       fatal = icmpv6_err_convert(type, code, &err);
        if (sk->sk_state == TCP_NEW_SYN_RECV)
-               return tcp_req_err(sk, seq);
+               return tcp_req_err(sk, seq, fatal);
 
        bh_lock_sock(sk);
        if (sock_owned_by_user(sk) && type != ICMPV6_PKT_TOOBIG)
@@ -400,7 +402,6 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
                goto out;
        }
 
-       icmpv6_err_convert(type, code, &err);
 
        /* Might be for an request_sock */
        switch (sk->sk_state) {