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authorJakub Kicinski <jakub.kicinski@netronome.com>2019-11-05 14:24:35 -0800
committerDavid S. Miller <davem@davemloft.net>2019-11-06 17:33:32 -0800
commit79ffe6087e9145d2377385cac48d0d6a6b4225a5 (patch)
tree7ad119676734db269b7ae127d3bf0908339306eb /net/tls/tls_main.c
parent02b1fa07bb58f5d1f349b5b09eb936739a7b20fc (diff)
net/tls: add a TX lock
TLS TX needs to release and re-acquire the socket lock if send buffer fills up. TLS SW TX path currently depends on only allowing one thread to enter the function by the abuse of sk_write_pending. If another writer is already waiting for memory no new ones are allowed in. This has two problems: - writers don't wake other threads up when they leave the kernel; meaning that this scheme works for single extra thread (second application thread or delayed work) because memory becoming available will send a wake up request, but as Mallesham and Pooja report with larger number of threads it leads to threads being put to sleep indefinitely; - the delayed work does not get _scheduled_ but it may _run_ when other writers are present leading to crashes as writers don't expect state to change under their feet (same records get pushed and freed multiple times); it's hard to reliably bail from the work, however, because the mere presence of a writer does not guarantee that the writer will push pending records before exiting. Ensuring wakeups always happen will make the code basically open code a mutex. Just use a mutex. The TLS HW TX path does not have any locking (not even the sk_write_pending hack), yet it uses a per-socket sg_tx_data array to push records. Fixes: a42055e8d2c3 ("net/tls: Add support for async encryption of records for performance") Reported-by: Mallesham Jatharakonda <mallesh537@gmail.com> Reported-by: Pooja Trivedi <poojatrivedi@gmail.com> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Reviewed-by: Simon Horman <simon.horman@netronome.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tls/tls_main.c')
-rw-r--r--net/tls/tls_main.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index ac88877dcade..0775ae40fcfb 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -267,6 +267,7 @@ void tls_ctx_free(struct sock *sk, struct tls_context *ctx)
memzero_explicit(&ctx->crypto_send, sizeof(ctx->crypto_send));
memzero_explicit(&ctx->crypto_recv, sizeof(ctx->crypto_recv));
+ mutex_destroy(&ctx->tx_lock);
if (sk)
kfree_rcu(ctx, rcu);
@@ -612,6 +613,7 @@ static struct tls_context *create_ctx(struct sock *sk)
if (!ctx)
return NULL;
+ mutex_init(&ctx->tx_lock);
rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
ctx->sk_proto = sk->sk_prot;
return ctx;