arm: crypto: reduce priority of bit-sliced AES cipher

Hi,

I'd like the following patch to be applied to stable for versions between 4.1 and 4.10 (inclusively).

This is a minimal fix for a bug where arm32 kernels can use a much slower implementation of AES than is actually available, potentially forcing vendors to disable encryption on their devices.

Min version is 4.1 because that was the first version to include the aes-ce algorithms.

Max version is 4.10 because in 4.11, this bug was fixed incidentally as part of a complete rewrite of the bit-sliced AES implementation.

---8<---

All the aes-bs (bit-sliced) and aes-ce (cryptographic extensions) algorithms had a priority of 300. This is undesirable because it means an aes-bs algorithm may be used when an aes-ce algorithm is available. The aes-ce algorithms have much better performance (up to 10x faster).

Fix it by decreasing the priority of the aes-bs algorithms to 250.

This was fixed upstream by commit cc477bf64573 ("crypto: arm/aes - replace bit-sliced OpenSSL NEON code"), but it was just a small part of a complete rewrite. This patch just fixes the priority bug for older kernels.

---
 arch/arm/crypto/aesbs-glue.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

index 0511a6cafe24..5d934a0039d7 100644
@@ -363,7 +363,7 @@ static struct crypto_alg aesbs_algs[] = { {
 }, {
 	.cra_name		= "cbc(aes)",
 	.cra_driver_name	= "cbc-aes-neonbs",
-	.cra_priority		= 300,
+	.cra_priority		= 250,
 	.cra_flags		= CRYPTO_ALG_TYPE_ABLKCIPHER|CRYPTO_ALG_ASYNC,
 	.cra_blocksize		= AES_BLOCK_SIZE,
 	.cra_ctxsize		= sizeof(struct async_helper_ctx),

@@ -383,7 +383,7 @@ static struct crypto_alg aesbs_algs[] = { {
 }, {
 	.cra_name		= "ctr(aes)",
 	.cra_driver_name	= "ctr-aes-neonbs",
-	.cra_priority		= 300,
+	.cra_priority		= 250,
 	.cra_flags		= CRYPTO_ALG_TYPE_ABLKCIPHER|CRYPTO_ALG_ASYNC,
 	.cra_blocksize		= 1,
 	.cra_ctxsize		= sizeof(struct async_helper_ctx),

@@ -403,7 +403,7 @@ static struct crypto_alg aesbs_algs[] = { {
 }, {
 	.cra_name		= "xts(aes)",
 	.cra_driver_name	= "xts-aes-neonbs",
-	.cra_priority		= 300,
+	.cra_priority		= 250,
 	.cra_flags		= CRYPTO_ALG_TYPE_ABLKCIPHER|CRYPTO_ALG_ASYNC,
 	.cra_blocksize		= AES_BLOCK_SIZE,
 	.cra_ctxsize		= sizeof(struct async_helper_ctx),

2.15.0.448.gf294e3d99a-goog

I'd say up to 20x is more accurate.

Thanks for the patch, now queued up.

greg k-h

This is a note to let you know that I've just added the patch titled

[PATCH -stable] arm: crypto: reduce priority of bit-sliced AES cipher

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arm-crypto-reduce-priority-of-bit-sliced-aes-cipher.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Eric Biggers <[email protected]>
Date: Fri, 17 Nov 2017 11:50:27 -0800
Subject: [PATCH -stable] arm: crypto: reduce priority of bit-sliced AES cipher
To: [email protected]
Cc: Ard Biesheuvel <[email protected]>, [email protected], Eric Biggers <[email protected]>
Message-ID: <[email protected]>

From: Eric Biggers <[email protected]>

[ Not upstream because this is a minimal fix for a bug where arm32
kernels can use a much slower implementation of AES than is actually available, potentially forcing vendors to disable encryption on their devices.]

All the aes-bs (bit-sliced) and aes-ce (cryptographic extensions) algorithms had a priority of 300. This is undesirable because it means an aes-bs algorithm may be used when an aes-ce algorithm is available. The aes-ce algorithms have much better performance (up to 10x faster).

Fix it by decreasing the priority of the aes-bs algorithms to 250.

This was fixed upstream by commit cc477bf64573 ("crypto: arm/aes - replace bit-sliced OpenSSL NEON code"), but it was just a small part of a complete rewrite. This patch just fixes the priority bug for older kernels.

---
 arch/arm/crypto/aesbs-glue.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

@@ -363,7 +363,7 @@ static struct crypto_alg aesbs_algs[] =
 }, {
 	.cra_name		= "cbc(aes)",
 	.cra_driver_name	= "cbc-aes-neonbs",
-	.cra_priority		= 300,
+	.cra_priority		= 250,
 	.cra_flags		= CRYPTO_ALG_TYPE_ABLKCIPHER|CRYPTO_ALG_ASYNC,
 	.cra_blocksize		= AES_BLOCK_SIZE,
 	.cra_ctxsize		= sizeof(struct async_helper_ctx),

@@ -383,7 +383,7 @@ static struct crypto_alg aesbs_algs[] =
 }, {
 	.cra_name		= "ctr(aes)",
 	.cra_driver_name	= "ctr-aes-neonbs",
-	.cra_priority		= 300,
+	.cra_priority		= 250,
 	.cra_flags		= CRYPTO_ALG_TYPE_ABLKCIPHER|CRYPTO_ALG_ASYNC,
 	.cra_blocksize		= 1,
 	.cra_ctxsize		= sizeof(struct async_helper_ctx),

@@ -403,7 +403,7 @@ static struct crypto_alg aesbs_algs[] =
 }, {
 	.cra_name		= "xts(aes)",
 	.cra_driver_name	= "xts-aes-neonbs",
-	.cra_priority		= 300,
+	.cra_priority		= 250,
 	.cra_flags		= CRYPTO_ALG_TYPE_ABLKCIPHER|CRYPTO_ALG_ASYNC,
 	.cra_blocksize		= AES_BLOCK_SIZE,
 	.cra_ctxsize		= sizeof(struct async_helper_ctx),

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/arm-crypto-reduce-priority-of-bit-sliced-aes-cipher.patch

This is a note to let you know that I've just added the patch titled

[PATCH -stable] arm: crypto: reduce priority of bit-sliced AES cipher

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arm-crypto-reduce-priority-of-bit-sliced-aes-cipher.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Eric Biggers <[email protected]>
Date: Fri, 17 Nov 2017 11:50:27 -0800
Subject: [PATCH -stable] arm: crypto: reduce priority of bit-sliced AES cipher
To: [email protected]
Cc: Ard Biesheuvel <[email protected]>, [email protected], Eric Biggers <[email protected]>
Message-ID: <[email protected]>

From: Eric Biggers <[email protected]>

[ Not upstream because this is a minimal fix for a bug where arm32
kernels can use a much slower implementation of AES than is actually available, potentially forcing vendors to disable encryption on their devices.]

All the aes-bs (bit-sliced) and aes-ce (cryptographic extensions) algorithms had a priority of 300. This is undesirable because it means an aes-bs algorithm may be used when an aes-ce algorithm is available. The aes-ce algorithms have much better performance (up to 10x faster).

Fix it by decreasing the priority of the aes-bs algorithms to 250.

This was fixed upstream by commit cc477bf64573 ("crypto: arm/aes - replace bit-sliced OpenSSL NEON code"), but it was just a small part of a complete rewrite. This patch just fixes the priority bug for older kernels.

---
 arch/arm/crypto/aesbs-glue.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

@@ -357,7 +357,7 @@ static struct crypto_alg aesbs_algs[] =
 }, {
 	.cra_name		= "cbc(aes)",
 	.cra_driver_name	= "cbc-aes-neonbs",
-	.cra_priority		= 300,
+	.cra_priority		= 250,
 	.cra_flags		= CRYPTO_ALG_TYPE_ABLKCIPHER|CRYPTO_ALG_ASYNC,
 	.cra_blocksize		= AES_BLOCK_SIZE,
 	.cra_ctxsize		= sizeof(struct async_helper_ctx),

@@ -377,7 +377,7 @@ static struct crypto_alg aesbs_algs[] =
 }, {
 	.cra_name		= "ctr(aes)",
 	.cra_driver_name	= "ctr-aes-neonbs",
-	.cra_priority		= 300,
+	.cra_priority		= 250,
 	.cra_flags		= CRYPTO_ALG_TYPE_ABLKCIPHER|CRYPTO_ALG_ASYNC,
 	.cra_blocksize		= 1,
 	.cra_ctxsize		= sizeof(struct async_helper_ctx),

@@ -397,7 +397,7 @@ static struct crypto_alg aesbs_algs[] =
 }, {
 	.cra_name		= "xts(aes)",
 	.cra_driver_name	= "xts-aes-neonbs",
-	.cra_priority		= 300,
+	.cra_priority		= 250,
 	.cra_flags		= CRYPTO_ALG_TYPE_ABLKCIPHER|CRYPTO_ALG_ASYNC,
 	.cra_blocksize		= AES_BLOCK_SIZE,
 	.cra_ctxsize		= sizeof(struct async_helper_ctx),

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/arm-crypto-reduce-priority-of-bit-sliced-aes-cipher.patch