From 9ea88a153001ffeb3d8810917e8eea62ca9b6f25 Mon Sep 17 00:00:00 2001 From: Dmitry Popov Date: Thu, 7 Aug 2014 02:38:22 +0400 Subject: [PATCH] tcp: md5: check md5 signature without socket lock Since a8afca032 (tcp: md5: protects md5sig_info with RCU) tcp_md5_do_lookup doesn't require socket lock, rcu_read_lock is enough. Therefore socket lock is no longer required for tcp_v{4,6}_inbound_md5_hash too, so we can move these calls (wrapped with rcu_read_{,un}lock) before bh_lock_sock: from tcp_v{4,6}_do_rcv to tcp_v{4,6}_rcv. Signed-off-by: Dmitry Popov Signed-off-by: David S. Miller --- net/ipv4/tcp_ipv4.c | 36 +++++++++++++++++++++++++----------- net/ipv6/tcp_ipv6.c | 25 +++++++++++++++++++------ 2 files changed, 44 insertions(+), 17 deletions(-) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 992a1f926009..dceff5fe8e66 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1167,7 +1167,8 @@ clear_hash_noput: } EXPORT_SYMBOL(tcp_v4_md5_hash_skb); -static bool tcp_v4_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb) +static bool __tcp_v4_inbound_md5_hash(struct sock *sk, + const struct sk_buff *skb) { /* * This gets called for each TCP segment that arrives @@ -1220,6 +1221,17 @@ static bool tcp_v4_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb) return false; } +static bool tcp_v4_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb) +{ + bool ret; + + rcu_read_lock(); + ret = __tcp_v4_inbound_md5_hash(sk, skb); + rcu_read_unlock(); + + return ret; +} + #endif static void tcp_v4_init_req(struct request_sock *req, struct sock *sk, @@ -1432,16 +1444,6 @@ static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb) int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) { struct sock *rsk; -#ifdef CONFIG_TCP_MD5SIG - /* - * We really want to reject the packet as early as possible - * if: - * o We're expecting an MD5'd packet and this is no MD5 tcp option - * o There is an MD5 option and we're not expecting one - */ - if (tcp_v4_inbound_md5_hash(sk, skb)) - goto discard; -#endif if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */ struct dst_entry *dst = sk->sk_rx_dst; @@ -1644,6 +1646,18 @@ process: if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) goto discard_and_relse; + +#ifdef CONFIG_TCP_MD5SIG + /* + * We really want to reject the packet as early as possible + * if: + * o We're expecting an MD5'd packet and this is no MD5 tcp option + * o There is an MD5 option and we're not expecting one + */ + if (tcp_v4_inbound_md5_hash(sk, skb)) + goto discard_and_relse; +#endif + nf_reset(skb); if (sk_filter(sk, skb)) diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 22055b098428..f2ce95502392 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -667,7 +667,8 @@ clear_hash_noput: return 1; } -static int tcp_v6_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb) +static int __tcp_v6_inbound_md5_hash(struct sock *sk, + const struct sk_buff *skb) { const __u8 *hash_location = NULL; struct tcp_md5sig_key *hash_expected; @@ -707,6 +708,18 @@ static int tcp_v6_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb) } return 0; } + +static int tcp_v6_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb) +{ + int ret; + + rcu_read_lock(); + ret = __tcp_v6_inbound_md5_hash(sk, skb); + rcu_read_unlock(); + + return ret; +} + #endif static void tcp_v6_init_req(struct request_sock *req, struct sock *sk, @@ -1247,11 +1260,6 @@ static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb) if (skb->protocol == htons(ETH_P_IP)) return tcp_v4_do_rcv(sk, skb); -#ifdef CONFIG_TCP_MD5SIG - if (tcp_v6_inbound_md5_hash(sk, skb)) - goto discard; -#endif - if (sk_filter(sk, skb)) goto discard; @@ -1424,6 +1432,11 @@ process: if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) goto discard_and_relse; +#ifdef CONFIG_TCP_MD5SIG + if (tcp_v6_inbound_md5_hash(sk, skb)) + goto discard_and_relse; +#endif + if (sk_filter(sk, skb)) goto discard_and_relse; -- 2.20.1