diff options
| author | Eric Dumazet <eric.dumazet@gmail.com> | 2011-04-21 09:45:37 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2011-04-28 13:16:35 -0700 |
| commit | f6d8bd051c391c1c0458a30b2a7abcd939329259 (patch) | |
| tree | 1dc4daecdeb0b42c2c6b59d7d6b41e091c11db5f /net/ipv4/ip_sockglue.c | |
| parent | 0a14842f5a3c0e88a1e59fac5c3025db39721f74 (diff) | |
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 <eric.dumazet@gmail.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/ip_sockglue.c')
| -rw-r--r-- | net/ipv4/ip_sockglue.c | 35 |
1 files changed, 24 insertions, 11 deletions
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index 9640900309b..ab0c9efd1ef 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -451,6 +451,11 @@ out: } +static void opt_kfree_rcu(struct rcu_head *head) +{ + kfree(container_of(head, struct ip_options_rcu, rcu)); +} + /* * Socket option code for IP. This is the end of the line after any * TCP,UDP etc options on an IP socket. @@ -497,13 +502,16 @@ static int do_ip_setsockopt(struct sock *sk, int level, switch (optname) { case IP_OPTIONS: { - struct ip_options *opt = NULL; + struct ip_options_rcu *old, *opt = NULL; + if (optlen > 40) goto e_inval; err = ip_options_get_from_user(sock_net(sk), &opt, optval, optlen); if (err) break; + old = rcu_dereference_protected(inet->inet_opt, + sock_owned_by_user(sk)); if (inet->is_icsk) { struct inet_connection_sock *icsk = inet_csk(sk); #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) @@ -512,17 +520,18 @@ static int do_ip_setsockopt(struct sock *sk, int level, (TCPF_LISTEN | TCPF_CLOSE)) && inet->inet_daddr != LOOPBACK4_IPV6)) { #endif - if (inet->opt) - icsk->icsk_ext_hdr_len -= inet->opt->optlen; + if (old) + icsk->icsk_ext_hdr_len -= old->opt.optlen; if (opt) - icsk->icsk_ext_hdr_len += opt->optlen; + icsk->icsk_ext_hdr_len += opt->opt.optlen; icsk->icsk_sync_mss(sk, icsk->icsk_pmtu_cookie); #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) } #endif } - opt = xchg(&inet->opt, opt); - kfree(opt); + rcu_assign_pointer(inet->inet_opt, opt); + if (old) + call_rcu(&old->rcu, opt_kfree_rcu); break; } case IP_PKTINFO: @@ -1081,12 +1090,16 @@ static int do_ip_getsockopt(struct sock *sk, int level, int optname, case IP_OPTIONS: { unsigned char optbuf[sizeof(struct ip_options)+40]; - struct ip_options * opt = (struct ip_options *)optbuf; + struct ip_options *opt = (struct ip_options *)optbuf; + struct ip_options_rcu *inet_opt; + + inet_opt = rcu_dereference_protected(inet->inet_opt, + sock_owned_by_user(sk)); opt->optlen = 0; - if (inet->opt) - memcpy(optbuf, inet->opt, - sizeof(struct ip_options)+ - inet->opt->optlen); + if (inet_opt) + memcpy(optbuf, &inet_opt->opt, + sizeof(struct ip_options) + + inet_opt->opt.optlen); release_sock(sk); if (opt->optlen == 0) |