net: tls: handle backlogging of crypto requests

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>

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 9374a61cef00b4f80eb78880e87b6eb513fc9452..63bef5666e36d71d39ace33c5fef07417a678810 100644 (file)
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -196,6 +196,17 @@ static void tls_decrypt_done(void *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);
@@ -269,6 +280,10 @@ 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;
@@ -449,6 +464,9 @@ static void tls_encrypt_done(void *data, int err)
        struct sk_msg *msg_en;
        struct sock *sk;
 
+       if (err == -EINPROGRESS) /* see the comment in tls_decrypt_done() */
+               return;
+
        msg_en = &rec->msg_encrypted;
 
        sk = rec->sk;
@@ -553,6 +571,10 @@ 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;