From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D9E9B39E6FD; Fri, 25 Sep 2026 20:24:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790367845; cv=none; b=C8geZNAJ4vOLq9IkbpX9NBOE7rPklKeQtr7KgDU8Q4uy/8xKNp0pdeQKjLdoUwg7oWshJctz5tsFf4PKNInIYf/Vj0X2yP2giYf0mOW16Ac/PX28zBrvf4c3yY4rvcdh0eNlo+bwUIRHxD4G4J3yi0FCjRP6Z7J7Anx4PIRhUwI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790367845; c=relaxed/simple; bh=sEy0iS3lMe+7dT7VRMQG77lvgBadr1yYxPHFXErlTAg=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=pNVmbEjahIhXBel5dBRvWX5/j9ynxjRCtCkzEnhRUJMLJU3FTUokhJlT1c9VgpQXy2R4O8eVeSN5EfolSLXDc56cMmiKu8anCzH5CCP8n+l4uggAfLig5ixUhiuIZPEYlXFh5dkY6q0AvLIxGU746iIgzr3ePPt5h4+IIk+ACCQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fXk6iOiF; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fXk6iOiF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 39DB31F000FF; Fri, 25 Sep 2026 20:24:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790367843; bh=0XtDr7CWLuuPjZmyPXX7gre02vj8EXdAecl3xCM4xLI=; h=From:To:Cc:Subject:Date; b=fXk6iOiFDfp2qzi6JReKLwJ9xcBr9WCwQ3EDjSGqsfsFnEt0x4ArV9IxRDkcj1hyF IlIovwFjZBVOkluBJ2OMvXgmWNqKDIrtXeZt2oZldErQlX77+InRPdO47h2YmPvh/W znwzDi6aAnO3NwYy9s0toEwgGlbc7+PxQIqV3Oh0RQVPkR/2aNKfEjCpd2jkyiGbAK YidyHZmRlEmvwYFEn7q1msBUbNqsy9ZQZjz0hEfwNCLLY1GJul0X6Z3NZsyS7LIsP7 92nvTRMGfN0ozGsODR6QE0lygvoGTKm1ZtYusv7GebbhctfHOo6FMxgSE5o3fc0Uw6 csQ/vsaXQG3Kw== From: Eric Biggers To: linux-crypto@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel , "Jason A . Donenfeld" , Herbert Xu , Eric Biggers Subject: [PATCH v2] crypto: aes - Fix undesired override of some optimized AES modes Date: Fri, 25 Sep 2026 13:23:53 -0700 Message-ID: <20260925202353.10763-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The new library APIs for AES encryption modes were wired up to the traditional crypto API via crypto/aes.c. However, for now the kernel is still in a transitional state where various architectures still have architecture-optimized implementations of AES modes in arch/*/crypto/, wired up to the traditional crypto API only. Because of that, the crypto/aes.c algorithms were given a cra_priority of only 110 to prevent them from overriding arch/*/crypto/ in the traditional crypto API. However, because of how the traditional crypto API works, the cra_priority trick doesn't work in cases where the relevant algorithm isn't directly implemented by arch/*/crypto/ but rather is provided by a template instance using other code in arch/*/crypto/. For example, x86 doesn't have its own "ccm(aes)" but rather relies on the "ccm" template constructing it from the x86-optimized "ctr(aes)". The existence of the library-based "ccm(aes)" prevents that, even though its priority is lower than what the template would produce. Thus, "ccm(aes)" ends up using the slower single-block AES code. Therefore, skip wiring up the relevant library-based code to the traditional crypto API on architectures where this problem can occur, as determined by what exists in arch/*/crypto/ for each architecture. This is ugly, but it's also temporary: these conditions will go away as architecture-optimized implementations of AES modes are migrated into the library. But until then, we need to prevent performance regressions by ensuring that the optimized code continues to be used. Note: "xts(aes)" is left alone. Though the "xts" template can use "ecb(aes)" as an inner algorithm, in practice this isn't very efficient and a dedicated "xts(aes)" is already provided in all the important cases anyway. (This omission is also consistent with the fact that the library isn't planned to provide a similar ECB-to-XTS "adapter".) Fixes: 20df21a482aa ("crypto: aes - Add CBC and CBC-CTS support using library") Fixes: 8ca62072faa1 ("crypto: aes - Add GCM support using library") Fixes: f70ad727d1d6 ("crypto: aes - Add CCM support using library") Signed-off-by: Eric Biggers --- This patch is intended to be taken through libcrypto-fixes v2: Fixed PowerPC config option, and resent as standalone patch crypto/aes.c | 39 ++++++++++++++++++++++++++++++++++++--- 1 file changed, 36 insertions(+), 3 deletions(-) diff --git a/crypto/aes.c b/crypto/aes.c index 94791f481e984..5046b887ac9a0 100644 --- a/crypto/aes.c +++ b/crypto/aes.c @@ -637,7 +637,17 @@ static struct skcipher_alg skcipher_algs[] = { .decrypt = crypto_aes_cbc_decrypt, }, #endif -#if IS_ENABLED(CONFIG_CRYPTO_CTS) +#if IS_ENABLED(CONFIG_CRYPTO_CTS) && \ + /* + * Skip registering this when it might block a "better" implementation + * from being instantiated via the "cts" template wrapping an arch- + * optimized "cbc(aes)" that hasn't yet been migrated into the library. + */ \ + !(IS_ENABLED(CONFIG_ARM) || \ + IS_ENABLED(CONFIG_ARM64) || \ + IS_ENABLED(CONFIG_PPC) || \ + IS_ENABLED(CONFIG_S390) || \ + IS_ENABLED(CONFIG_SPARC)) { .base.cra_name = "cts(cbc(aes))", .base.cra_driver_name = "cts-cbc-aes-lib", @@ -980,7 +990,18 @@ static __maybe_unused int crypto_aes_ccm_decrypt(struct aead_request *req) } static struct aead_alg aead_algs[] = { -#if IS_ENABLED(CONFIG_CRYPTO_GCM) +#if IS_ENABLED(CONFIG_CRYPTO_GCM) && \ + /* + * Skip registering these when they might block "better" implementations + * from being instantiated via the corresponding templates using + * arch-optimized code that hasn't yet been migrated into the library. + */ \ + !(IS_ENABLED(CONFIG_ARM) || \ + IS_ENABLED(CONFIG_ARM64) || \ + IS_ENABLED(CONFIG_PPC) || \ + IS_ENABLED(CONFIG_RISCV) || \ + IS_ENABLED(CONFIG_S390) || \ + IS_ENABLED(CONFIG_SPARC)) { .base.cra_name = "gcm(aes)", .base.cra_driver_name = "gcm-aes-lib", @@ -1012,7 +1033,19 @@ static struct aead_alg aead_algs[] = { .chunksize = AES_BLOCK_SIZE, }, #endif /* CONFIG_CRYPTO_GCM */ -#if IS_ENABLED(CONFIG_CRYPTO_CCM) +#if IS_ENABLED(CONFIG_CRYPTO_CCM) && \ + /* + * Skip registering this when it might block a "better" implementation + * from being instantiated via the "ccm" template wrapping an arch- + * optimized "ctr(aes)" that hasn't yet been migrated into the library. + */ \ + !(IS_ENABLED(CONFIG_ARM) || \ + IS_ENABLED(CONFIG_ARM64) || \ + IS_ENABLED(CONFIG_PPC) || \ + IS_ENABLED(CONFIG_RISCV) || \ + IS_ENABLED(CONFIG_S390) || \ + IS_ENABLED(CONFIG_SPARC) || \ + IS_ENABLED(CONFIG_X86)) { .base.cra_name = "ccm(aes)", .base.cra_driver_name = "ccm-aes-lib", base-commit: 93f51579e7df248780214094418f205253383cc5 -- 2.55.0