From 35790c0421121364883a167bab8a2e37e1f67f78 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 16 May 2010 00:34:04 -0700 Subject: tcp: fix MD5 (RFC2385) support TCP MD5 support uses percpu data for temporary storage. It currently disables preemption so that same storage cannot be reclaimed by another thread on same cpu. We also have to make sure a softirq handler wont try to use also same context. Various bug reports demonstrated corruptions. Fix is to disable preemption and BH. Reported-by: Bhaskar Dutta Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp.c | 34 ++++++++++++++++++++++++---------- 1 file changed, 24 insertions(+), 10 deletions(-) (limited to 'net/ipv4/tcp.c') diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 0f8caf64caa3..296150b2a62f 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2839,7 +2839,6 @@ static void __tcp_free_md5sig_pool(struct tcp_md5sig_pool * __percpu *pool) if (p->md5_desc.tfm) crypto_free_hash(p->md5_desc.tfm); kfree(p); - p = NULL; } } free_percpu(pool); @@ -2937,25 +2936,40 @@ retry: EXPORT_SYMBOL(tcp_alloc_md5sig_pool); -struct tcp_md5sig_pool *__tcp_get_md5sig_pool(int cpu) + +/** + * tcp_get_md5sig_pool - get md5sig_pool for this user + * + * We use percpu structure, so if we succeed, we exit with preemption + * and BH disabled, to make sure another thread or softirq handling + * wont try to get same context. + */ +struct tcp_md5sig_pool *tcp_get_md5sig_pool(void) { struct tcp_md5sig_pool * __percpu *p; - spin_lock_bh(&tcp_md5sig_pool_lock); + + local_bh_disable(); + + spin_lock(&tcp_md5sig_pool_lock); p = tcp_md5sig_pool; if (p) tcp_md5sig_users++; - spin_unlock_bh(&tcp_md5sig_pool_lock); - return (p ? *per_cpu_ptr(p, cpu) : NULL); -} + spin_unlock(&tcp_md5sig_pool_lock); + + if (p) + return *per_cpu_ptr(p, smp_processor_id()); -EXPORT_SYMBOL(__tcp_get_md5sig_pool); + local_bh_enable(); + return NULL; +} +EXPORT_SYMBOL(tcp_get_md5sig_pool); -void __tcp_put_md5sig_pool(void) +void tcp_put_md5sig_pool(void) { + local_bh_enable(); tcp_free_md5sig_pool(); } - -EXPORT_SYMBOL(__tcp_put_md5sig_pool); +EXPORT_SYMBOL(tcp_put_md5sig_pool); int tcp_md5_hash_header(struct tcp_md5sig_pool *hp, struct tcphdr *th) -- cgit v1.2.3