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

28 Mar 2024

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/9681d1febfec295449a62300938ed2ae66983f28.1694...
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: 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 2bd27b777..61b01dfc6 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;
@@ -452,6 +467,9 @@ static void tls_encrypt_done(crypto_completion_data_t *data, int err)
    bool ready = false;
    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;
@@ -560,6 +578,10 @@ 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;
-- 
2.34.1


    

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