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/udp.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) (limited to 'net/ipv4/udp.c') diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index bc0dab2593e0..544f435d1aff 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -804,6 +804,7 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, int corkreq = up->corkflag || msg->msg_flags&MSG_MORE; int (*getfrag)(void *, char *, int, int, int, struct sk_buff *); struct sk_buff *skb; + struct ip_options_data opt_copy; if (len > 0xFFFF) return -EMSGSIZE; @@ -877,22 +878,32 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, free = 1; connected = 0; } - 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(); + } saddr = ipc.addr; ipc.addr = faddr = daddr; - if (ipc.opt && ipc.opt->srr) { + if (ipc.opt && ipc.opt->opt.srr) { if (!daddr) return -EINVAL; - faddr = ipc.opt->faddr; + faddr = ipc.opt->opt.faddr; connected = 0; } tos = RT_TOS(inet->tos); if (sock_flag(sk, SOCK_LOCALROUTE) || (msg->msg_flags & MSG_DONTROUTE) || - (ipc.opt && ipc.opt->is_strictroute)) { + (ipc.opt && ipc.opt->opt.is_strictroute)) { tos |= RTO_ONLINK; connected = 0; } -- cgit v1.2.3