From 459837b522f7dff3b6681f534d8fff4eca19b7d1 Mon Sep 17 00:00:00 2001 From: Dmitry Safonov Date: Wed, 23 Nov 2022 17:38:57 +0000 Subject: net/tcp: Disable TCP-MD5 static key on tcp_md5sig_info destruction To do that, separate two scenarios: - where it's the first MD5 key on the system, which means that enabling of the static key may need to sleep; - copying of an existing key from a listening socket to the request socket upon receiving a signed TCP segment, where static key was already enabled (when the key was added to the listening socket). Now the life-time of the static branch for TCP-MD5 is until: - last tcp_md5sig_info is destroyed - last socket in time-wait state with MD5 key is closed. Which means that after all sockets with TCP-MD5 keys are gone, the system gets back the performance of disabled md5-key static branch. While at here, provide static_key_fast_inc() helper that does ref counter increment in atomic fashion (without grabbing cpus_read_lock() on CONFIG_JUMP_LABEL=y). This is needed to add a new user for a static_key when the caller controls the lifetime of another user. Signed-off-by: Dmitry Safonov Acked-by: Jakub Kicinski Reviewed-by: Eric Dumazet Signed-off-by: Jakub Kicinski --- net/ipv4/tcp_minisocks.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) (limited to 'net/ipv4/tcp_minisocks.c') diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index c375f603a16c..6908812d50d3 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -291,13 +291,19 @@ void tcp_time_wait(struct sock *sk, int state, int timeo) */ do { tcptw->tw_md5_key = NULL; - if (static_branch_unlikely(&tcp_md5_needed)) { + if (static_branch_unlikely(&tcp_md5_needed.key)) { struct tcp_md5sig_key *key; key = tp->af_specific->md5_lookup(sk, sk); if (key) { tcptw->tw_md5_key = kmemdup(key, sizeof(*key), GFP_ATOMIC); - BUG_ON(tcptw->tw_md5_key && !tcp_alloc_md5sig_pool()); + if (!tcptw->tw_md5_key) + break; + BUG_ON(!tcp_alloc_md5sig_pool()); + if (!static_key_fast_inc_not_disabled(&tcp_md5_needed.key.key)) { + kfree(tcptw->tw_md5_key); + tcptw->tw_md5_key = NULL; + } } } } while (0); @@ -337,11 +343,13 @@ EXPORT_SYMBOL(tcp_time_wait); void tcp_twsk_destructor(struct sock *sk) { #ifdef CONFIG_TCP_MD5SIG - if (static_branch_unlikely(&tcp_md5_needed)) { + if (static_branch_unlikely(&tcp_md5_needed.key)) { struct tcp_timewait_sock *twsk = tcp_twsk(sk); - if (twsk->tw_md5_key) + if (twsk->tw_md5_key) { kfree_rcu(twsk->tw_md5_key, rcu); + static_branch_slow_dec_deferred(&tcp_md5_needed); + } } #endif } -- cgit v1.2.3-70-g09d2 From c5b8b515a211377e78bb7807fe3e6e7212626545 Mon Sep 17 00:00:00 2001 From: Dmitry Safonov Date: Wed, 23 Nov 2022 17:38:59 +0000 Subject: net/tcp: Separate initialization of twsk Convert BUG_ON() to WARN_ON_ONCE() and warn as well for unlikely static key int overflow error-path. Signed-off-by: Dmitry Safonov Acked-by: Jakub Kicinski Reviewed-by: Eric Dumazet Signed-off-by: Jakub Kicinski --- net/ipv4/tcp_minisocks.c | 61 +++++++++++++++++++++++++++--------------------- 1 file changed, 35 insertions(+), 26 deletions(-) (limited to 'net/ipv4/tcp_minisocks.c') diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index 6908812d50d3..e002f2e1d4f2 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -240,6 +240,40 @@ kill: } EXPORT_SYMBOL(tcp_timewait_state_process); +static void tcp_time_wait_init(struct sock *sk, struct tcp_timewait_sock *tcptw) +{ +#ifdef CONFIG_TCP_MD5SIG + const struct tcp_sock *tp = tcp_sk(sk); + struct tcp_md5sig_key *key; + + /* + * The timewait bucket does not have the key DB from the + * sock structure. We just make a quick copy of the + * md5 key being used (if indeed we are using one) + * so the timewait ack generating code has the key. + */ + tcptw->tw_md5_key = NULL; + if (!static_branch_unlikely(&tcp_md5_needed.key)) + return; + + key = tp->af_specific->md5_lookup(sk, sk); + if (key) { + tcptw->tw_md5_key = kmemdup(key, sizeof(*key), GFP_ATOMIC); + if (!tcptw->tw_md5_key) + return; + if (!tcp_alloc_md5sig_pool()) + goto out_free; + if (!static_key_fast_inc_not_disabled(&tcp_md5_needed.key.key)) + goto out_free; + } + return; +out_free: + WARN_ON_ONCE(1); + kfree(tcptw->tw_md5_key); + tcptw->tw_md5_key = NULL; +#endif +} + /* * Move a socket to time-wait or dead fin-wait-2 state. */ @@ -282,32 +316,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo) } #endif -#ifdef CONFIG_TCP_MD5SIG - /* - * The timewait bucket does not have the key DB from the - * sock structure. We just make a quick copy of the - * md5 key being used (if indeed we are using one) - * so the timewait ack generating code has the key. - */ - do { - tcptw->tw_md5_key = NULL; - if (static_branch_unlikely(&tcp_md5_needed.key)) { - struct tcp_md5sig_key *key; - - key = tp->af_specific->md5_lookup(sk, sk); - if (key) { - tcptw->tw_md5_key = kmemdup(key, sizeof(*key), GFP_ATOMIC); - if (!tcptw->tw_md5_key) - break; - BUG_ON(!tcp_alloc_md5sig_pool()); - if (!static_key_fast_inc_not_disabled(&tcp_md5_needed.key.key)) { - kfree(tcptw->tw_md5_key); - tcptw->tw_md5_key = NULL; - } - } - } - } while (0); -#endif + tcp_time_wait_init(sk, tcptw); /* Get the TIME_WAIT timeout firing. */ if (timeo < rto) -- cgit v1.2.3-70-g09d2