On 2025-06-04 11:54, Herbert Xu wrote:
On Tue, Jun 03, 2025 at 03:49:16PM +0200, Harald Freudenberger wrote:
Hello Herbert
I am facing a weird issue with my phmac implementation since kernel
5.15 has
been released. The algorithm registers fine but obviously it is not
self-tested
and thus you can't access it via AF_ALG or with an in-kernel customer.
So the issue is that this algorithm cannot have a fallback, because
the key is held in hardware only.
Please try the following patch and set the bit CRYPTO_ALG_NO_FALLBACK
and see if it works.
Thanks,
---8<---
Some drivers cannot have a fallback, e.g., because the key is held
in hardwre. Allow these to be used with ahash by adding the bit
CRYPTO_ALG_NO_FALLBACK.
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
diff --git a/crypto/ahash.c b/crypto/ahash.c
index e10bc2659ae4..bd9e49950201 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -347,6 +347,9 @@ static int ahash_do_req_chain(struct ahash_request
*req,
if (crypto_ahash_statesize(tfm) > HASH_MAX_STATESIZE)
return -ENOSYS;
+ if (!crypto_ahash_need_fallback(tfm))
+ return -ENOSYS;
+
{
u8 state[HASH_MAX_STATESIZE];
@@ -952,6 +955,10 @@ static int ahash_prepare_alg(struct ahash_alg
*alg)
base->cra_reqsize > MAX_SYNC_HASH_REQSIZE)
return -EINVAL;
+ if (base->cra_flags & CRYPTO_ALG_NEED_FALLBACK &&
+ base->cra_flags & CRYPTO_ALG_NO_FALLBACK)
+ return -EINVAL;
+
err = hash_prepare_alg(&alg->halg);
if (err)
return err;
@@ -960,7 +967,8 @@ static int ahash_prepare_alg(struct ahash_alg *alg)
base->cra_flags |= CRYPTO_ALG_TYPE_AHASH;
if ((base->cra_flags ^ CRYPTO_ALG_REQ_VIRT) &
- (CRYPTO_ALG_ASYNC | CRYPTO_ALG_REQ_VIRT))
+ (CRYPTO_ALG_ASYNC | CRYPTO_ALG_REQ_VIRT) &&
+ !(base->cra_flags & CRYPTO_ALG_NO_FALLBACK))
base->cra_flags |= CRYPTO_ALG_NEED_FALLBACK;
if (!alg->setkey)
diff --git a/include/linux/crypto.h b/include/linux/crypto.h
index b50f1954d1bb..a2137e19be7d 100644
--- a/include/linux/crypto.h
+++ b/include/linux/crypto.h
@@ -136,6 +136,9 @@
/* Set if the algorithm supports virtual addresses. */
#define CRYPTO_ALG_REQ_VIRT 0x00040000
+/* Set if the algorithm cannot have a fallback (e.g., phmac). */
+#define CRYPTO_ALG_NO_FALLBACK 0x00080000
+
/* The high bits 0xff000000 are reserved for type-specific flags. */
/*
Works perfect - tested on a fresh clone of cryptodev-2.6 with my
phmac v12 patches on top.
Add a Tested-by: Harald Freudenberger <freude@xxxxxxxxxxxxx>
Please push into next, maybe fix the typo "hardwre" -> "hardware"
Thanks
