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authorEric Dumazet <eric.dumazet@gmail.com>2011-04-21 09:45:37 +0000
committerDavid S. Miller <davem@davemloft.net>2011-04-28 13:16:35 -0700
commitf6d8bd051c391c1c0458a30b2a7abcd939329259 (patch)
tree1dc4daecdeb0b42c2c6b59d7d6b41e091c11db5f /net/ipv4/tcp_ipv4.c
parent0a14842f5a3c0e88a1e59fac5c3025db39721f74 (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/tcp_ipv4.c')
-rw-r--r--net/ipv4/tcp_ipv4.c34
1 files changed, 20 insertions, 14 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 310454c2f4d1..d60732fe5f21 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -154,6 +154,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
struct flowi4 fl4;
struct rtable *rt;
int err;
+ struct ip_options_rcu *inet_opt;
if (addr_len < sizeof(struct sockaddr_in))
return -EINVAL;
@@ -162,10 +163,12 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
return -EAFNOSUPPORT;
nexthop = daddr = usin->sin_addr.s_addr;
- if (inet->opt && inet->opt->srr) {
+ inet_opt = rcu_dereference_protected(inet->inet_opt,
+ sock_owned_by_user(sk));
+ if (inet_opt && inet_opt->opt.srr) {
if (!daddr)
return -EINVAL;
- nexthop = inet->opt->faddr;
+ nexthop = inet_opt->opt.faddr;
}
orig_sport = inet->inet_sport;
@@ -186,7 +189,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
return -ENETUNREACH;
}
- if (!inet->opt || !inet->opt->srr)
+ if (!inet_opt || !inet_opt->opt.srr)
daddr = rt->rt_dst;
if (!inet->inet_saddr)
@@ -222,8 +225,8 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
inet->inet_daddr = daddr;
inet_csk(sk)->icsk_ext_hdr_len = 0;
- if (inet->opt)
- inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
+ if (inet_opt)
+ inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
tp->rx_opt.mss_clamp = TCP_MSS_DEFAULT;
@@ -820,17 +823,18 @@ static void syn_flood_warning(const struct sk_buff *skb)
/*
* Save and compile IPv4 options into the request_sock if needed.
*/
-static struct ip_options *tcp_v4_save_options(struct sock *sk,
- struct sk_buff *skb)
+static struct ip_options_rcu *tcp_v4_save_options(struct sock *sk,
+ struct sk_buff *skb)
{
- struct ip_options *opt = &(IPCB(skb)->opt);
- struct ip_options *dopt = NULL;
+ const struct ip_options *opt = &(IPCB(skb)->opt);
+ struct ip_options_rcu *dopt = NULL;
if (opt && opt->optlen) {
- int opt_size = optlength(opt);
+ int opt_size = sizeof(*dopt) + opt->optlen;
+
dopt = kmalloc(opt_size, GFP_ATOMIC);
if (dopt) {
- if (ip_options_echo(dopt, skb)) {
+ if (ip_options_echo(&dopt->opt, skb)) {
kfree(dopt);
dopt = NULL;
}
@@ -1411,6 +1415,7 @@ struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
#ifdef CONFIG_TCP_MD5SIG
struct tcp_md5sig_key *key;
#endif
+ struct ip_options_rcu *inet_opt;
if (sk_acceptq_is_full(sk))
goto exit_overflow;
@@ -1431,13 +1436,14 @@ struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
newinet->inet_daddr = ireq->rmt_addr;
newinet->inet_rcv_saddr = ireq->loc_addr;
newinet->inet_saddr = ireq->loc_addr;
- newinet->opt = ireq->opt;
+ inet_opt = ireq->opt;
+ rcu_assign_pointer(newinet->inet_opt, inet_opt);
ireq->opt = NULL;
newinet->mc_index = inet_iif(skb);
newinet->mc_ttl = ip_hdr(skb)->ttl;
inet_csk(newsk)->icsk_ext_hdr_len = 0;
- if (newinet->opt)
- inet_csk(newsk)->icsk_ext_hdr_len = newinet->opt->optlen;
+ if (inet_opt)
+ inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
newinet->inet_id = newtp->write_seq ^ jiffies;
tcp_mtup_init(newsk);

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