From f6d8bd051c391c1c0458a30b2a7abcd939329259 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 21 Apr 2011 09:45:37 +0000 Subject: inet: add RCU protection to inet->opt We lack proper synchronization to manipulate inet->opt ip_options Problem is ip_make_skb() calls ip_setup_cork() and ip_setup_cork() possibly makes a copy of ipc->opt (struct ip_options), without any protection against another thread manipulating inet->opt. Another thread can change inet->opt pointer and free old one under us. Use RCU to protect inet->opt (changed to inet->inet_opt). Instead of handling atomic refcounts, just copy ip_options when necessary, to avoid cache line dirtying. We cant insert an rcu_head in struct ip_options since its included in skb->cb[], so this patch is large because I had to introduce a new ip_options_rcu structure. Signed-off-by: Eric Dumazet Cc: Herbert Xu Signed-off-by: David S. Miller --- net/ipv4/syncookies.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'net/ipv4/syncookies.c') diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c index 71e029691908..26461492a847 100644 --- a/net/ipv4/syncookies.c +++ b/net/ipv4/syncookies.c @@ -321,10 +321,10 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, * the ACK carries the same options again (see RFC1122 4.2.3.8) */ if (opt && opt->optlen) { - int opt_size = sizeof(struct ip_options) + opt->optlen; + int opt_size = sizeof(struct ip_options_rcu) + opt->optlen; ireq->opt = kmalloc(opt_size, GFP_ATOMIC); - if (ireq->opt != NULL && ip_options_echo(ireq->opt, skb)) { + if (ireq->opt != NULL && ip_options_echo(&ireq->opt->opt, skb)) { kfree(ireq->opt); ireq->opt = NULL; } -- cgit v1.2.3-58-ga151