From: Eric Dumazet edumazet@google.com
[ Upstream commit ddf251fa2bc1d3699eec0bae6ed0bc373b8fda79 ]
Whenever tcpm_new() reclaims an old entry, tcpm_suck_dst() would overwrite data that could be read from tcp_fastopen_cache_get() or tcp_metrics_fill_info().
We need to acquire fastopen_seqlock to maintain consistency.
For newly allocated objects, tcpm_new() can switch to kzalloc() to avoid an extra fastopen_seqlock acquisition.
Fixes: 1fe4c481ba63 ("net-tcp: Fast Open client - cookie cache") Signed-off-by: Eric Dumazet edumazet@google.com Cc: Yuchung Cheng ycheng@google.com Reviewed-by: Kuniyuki Iwashima kuniyu@amazon.com Link: https://lore.kernel.org/r/20230802131500.1478140-7-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/tcp_metrics.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c index 3d0452bb6c2a1..e89e19a6852ce 100644 --- a/net/ipv4/tcp_metrics.c +++ b/net/ipv4/tcp_metrics.c @@ -93,6 +93,7 @@ static struct tcpm_hash_bucket *tcp_metrics_hash __read_mostly; static unsigned int tcp_metrics_hash_log __read_mostly;
static DEFINE_SPINLOCK(tcp_metrics_lock); +static DEFINE_SEQLOCK(fastopen_seqlock);
static void tcpm_suck_dst(struct tcp_metrics_block *tm, const struct dst_entry *dst, @@ -129,11 +130,13 @@ static void tcpm_suck_dst(struct tcp_metrics_block *tm, tcp_metric_set(tm, TCP_METRIC_REORDERING, dst_metric_raw(dst, RTAX_REORDERING)); if (fastopen_clear) { + write_seqlock(&fastopen_seqlock); tm->tcpm_fastopen.mss = 0; tm->tcpm_fastopen.syn_loss = 0; tm->tcpm_fastopen.try_exp = 0; tm->tcpm_fastopen.cookie.exp = false; tm->tcpm_fastopen.cookie.len = 0; + write_sequnlock(&fastopen_seqlock); } }
@@ -194,7 +197,7 @@ static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst, } tm = oldest; } else { - tm = kmalloc(sizeof(*tm), GFP_ATOMIC); + tm = kzalloc(sizeof(*tm), GFP_ATOMIC); if (!tm) goto out_unlock; } @@ -204,7 +207,7 @@ static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst, tm->tcpm_saddr = *saddr; tm->tcpm_daddr = *daddr;
- tcpm_suck_dst(tm, dst, true); + tcpm_suck_dst(tm, dst, reclaim);
if (likely(!reclaim)) { tm->tcpm_next = tcp_metrics_hash[hash].chain; @@ -551,8 +554,6 @@ bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst) return ret; }
-static DEFINE_SEQLOCK(fastopen_seqlock); - void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, struct tcp_fastopen_cookie *cookie) {