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/raw.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) (limited to 'net/ipv4/raw.c') diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c index abf14dbcb3b..a8659e0c4a6 100644 --- a/net/ipv4/raw.c +++ b/net/ipv4/raw.c @@ -460,6 +460,7 @@ static int raw_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, __be32 saddr; u8 tos; int err; + struct ip_options_data opt_copy; err = -EMSGSIZE; if (len > 0xFFFF) @@ -520,8 +521,18 @@ static int raw_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, saddr = ipc.addr; ipc.addr = daddr; - if (!ipc.opt) - ipc.opt = inet->opt; + if (!ipc.opt) { + struct ip_options_rcu *inet_opt; + + rcu_read_lock(); + inet_opt = rcu_dereference(inet->inet_opt); + if (inet_opt) { + memcpy(&opt_copy, inet_opt, + sizeof(*inet_opt) + inet_opt->opt.optlen); + ipc.opt = &opt_copy.opt; + } + rcu_read_unlock(); + } if (ipc.opt) { err = -EINVAL; @@ -530,10 +541,10 @@ static int raw_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, */ if (inet->hdrincl) goto done; - if (ipc.opt->srr) { + if (ipc.opt->opt.srr) { if (!daddr) goto done; - daddr = ipc.opt->faddr; + daddr = ipc.opt->opt.faddr; } } tos = RT_CONN_FLAGS(sk); -- cgit v1.2.3