[PATCH v2 6.1.y] net: tls: handle backlogging of crypto requests

Srish Srinivasan
2024-03-29T10:25:54Z

From: Jakub Kicinski <kuba@kernel.org>

commit 8590541473188741055d27b955db0777569438e3 upstream

Since we're setting the CRYPTO_TFM_REQ_MAY_BACKLOG flag on our
requests to the crypto API, crypto_aead_{encrypt,decrypt} can return
-EBUSY instead of -EINPROGRESS in valid situations. For example, when
the cryptd queue for AESNI is full (easy to trigger with an
artificially low cryptd.cryptd_max_cpu_qlen), requests will be enqueued
to the backlog but still processed. In that case, the async callback
will also be called twice: first with err == -EINPROGRESS, which it
seems we can just ignore, then with err == 0.

Compared to Sabrina's original patch this version uses the new
tls_*crypt_async_wait() helpers and converts the EBUSY to
EINPROGRESS to avoid having to modify all the error handling
paths. The handling is identical.

Fixes: a54667f6728c ("tls: Add support for encryption using async offload accelerator")
Fixes: 94524d8fc965 ("net/tls: Add support for async decryption of tls records")
Co-developed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://lore.kernel.org/netdev/9681d1febfec295449a62300938ed2ae66983f28.1694018970.git.sd@queasysnail.net/
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[Srish: v2: fixed hunk failures
fixed merge-conflict in stable branch linux-6.1.y,
needs to go on top of https://lore.kernel.org/stable/20240307155930.913525-1-lee@kernel.org/]
Signed-off-by: Srish Srinivasan <srish.srinivasan@broadcom.com>
---
net/tls/tls_sw.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index d53587ff9..e723584fc 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -195,6 +195,17 @@ static void tls_decrypt_done(crypto_completion_data_t *data, int err)
struct sock *sk;
int aead_size;

+ /* If requests get too backlogged crypto API returns -EBUSY and calls
+ * ->complete(-EINPROGRESS) immediately followed by ->complete(0)
+ * to make waiting for backlog to flush with crypto_wait_req() easier.
+ * First wait converts -EBUSY -> -EINPROGRESS, and the second one
+ * -EINPROGRESS -> 0.
+ * We have a single struct crypto_async_request per direction, this
+ * scheme doesn't help us, so just ignore the first ->complete().
+ */
+ if (err == -EINPROGRESS)
+ return;
+
aead_size = sizeof(*aead_req) + crypto_aead_reqsize(aead);
aead_size = ALIGN(aead_size, __alignof__(*dctx));
dctx = (void *)((u8 *)aead_req + aead_size);
@@ -268,6 +279,10 @@ static int tls_do_decryption(struct sock *sk,
}

ret = crypto_aead_decrypt(aead_req);
+ if (ret == -EBUSY) {
+ ret = tls_decrypt_async_wait(ctx);
+ ret = ret ?: -EINPROGRESS;
+ }
if (ret == -EINPROGRESS) {
if (darg->async)
return 0;
@@ -451,6 +466,9 @@ static void tls_encrypt_done(crypto_completion_data_t *data, int err)
struct tls_rec *rec;
struct sock *sk;

+ if (err == -EINPROGRESS) /* see the comment in tls_decrypt_done() */
+ return;
+
rec = container_of(aead_req, struct tls_rec, aead_req);
msg_en = &rec->msg_encrypted;

@@ -556,6 +574,10 @@ static int tls_do_encryption(struct sock *sk,
atomic_inc(&ctx->encrypt_pending);

rc = crypto_aead_encrypt(aead_req);
+ if (rc == -EBUSY) {
+ rc = tls_encrypt_async_wait(ctx);
+ rc = rc ?: -EINPROGRESS;
+ }
if (!rc || rc != -EINPROGRESS) {
atomic_dec(&ctx->encrypt_pending);
sge->offset -= prot->prepend_size;
--
2.39.0