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tcp/dccp: fix ireq->pktopts race 

IPv6 request sockets store a pointer to skb containing the SYN packet
to be able to transfer it to full blown socket when 3WHS is done
(ireq->pktopts -> np->pktoptions)

As explained in commit 5e0724d027 ("tcp/dccp: fix hashdance race for
passive sessions"), we must transfer the skb only if we won the
hashdance race, if multiple cpus receive the 'ack' packet completing
3WHS at the same time.

Fixes: e994b2f0fb ("tcp: do not lock listener to process SYN packets")
Fixes: 079096f103 ("tcp/dccp: install syn_recv requests into ehash table")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2015-10-30 09:46:12 -07:00 committed by David S. Miller
parent 7b5654349e
commit ce1050089c
2 changed files with 17 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
net/dccp/ipv6.c
View File

@ -477,15 +477,7 @@ static struct sock *dccp_v6_request_recv_sock(const struct sock *sk,
/* Clone RX bits */
newnp->rxopt.all = np->rxopt.all;
/* Clone pktoptions received with SYN */
newnp->pktoptions = NULL;
if (ireq->pktopts != NULL) {
newnp->pktoptions = skb_clone(ireq->pktopts, GFP_ATOMIC);
consume_skb(ireq->pktopts);
ireq->pktopts = NULL;
if (newnp->pktoptions)
skb_set_owner_r(newnp->pktoptions, newsk);
}
newnp->opt = NULL;
newnp->mcast_oif = inet6_iif(skb);
newnp->mcast_hops = ipv6_hdr(skb)->hop_limit;
@ -515,6 +507,14 @@ static struct sock *dccp_v6_request_recv_sock(const struct sock *sk,
goto out;
}
*own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash));
/* Clone pktoptions received with SYN, if we own the req */
if (*own_req && ireq->pktopts) {
newnp->pktoptions = skb_clone(ireq->pktopts, GFP_ATOMIC);
consume_skb(ireq->pktopts);
ireq->pktopts = NULL;
if (newnp->pktoptions)
skb_set_owner_r(newnp->pktoptions, newsk);
}
return newsk;

18
net/ipv6/tcp_ipv6.c
View File

@ -1084,16 +1084,7 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
/* Clone RX bits */
newnp->rxopt.all = np->rxopt.all;
/* Clone pktoptions received with SYN */
newnp->pktoptions = NULL;
if (ireq->pktopts) {
newnp->pktoptions = skb_clone(ireq->pktopts,
sk_gfp_atomic(sk, GFP_ATOMIC));
consume_skb(ireq->pktopts);
ireq->pktopts = NULL;
if (newnp->pktoptions)
skb_set_owner_r(newnp->pktoptions, newsk);
}
newnp->opt = NULL;
newnp->mcast_oif = tcp_v6_iif(skb);
newnp->mcast_hops = ipv6_hdr(skb)->hop_limit;
@ -1149,6 +1140,15 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
goto out;
}
*own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash));
/* Clone pktoptions received with SYN, if we own the req */
if (*own_req && ireq->pktopts) {
newnp->pktoptions = skb_clone(ireq->pktopts,
sk_gfp_atomic(sk, GFP_ATOMIC));
consume_skb(ireq->pktopts);
ireq->pktopts = NULL;
if (newnp->pktoptions)
skb_set_owner_r(newnp->pktoptions, newsk);
}
return newsk;