From bb40d32689d73c46de39a0529d551f523f21dc9b Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Sun, 8 Oct 2023 19:31:16 -0700 Subject: [PATCH 1/1] crypto: xts - use 'spawn' for underlying single-block cipher Since commit adad556efcdd ("crypto: api - Fix built-in testing dependency failures"), the following warning appears when booting an x86_64 kernel that is configured with CONFIG_CRYPTO_MANAGER_EXTRA_TESTS=y and CONFIG_CRYPTO_AES_NI_INTEL=y, even when CONFIG_CRYPTO_XTS=y and CONFIG_CRYPTO_AES=y: alg: skcipher: skipping comparison tests for xts-aes-aesni because xts(ecb(aes-generic)) is unavailable This is caused by an issue in the xts template where it allocates an "aes" single-block cipher without declaring a dependency on it via the crypto_spawn mechanism. This issue was exposed by the above commit because it reversed the order that the algorithms are tested in. Specifically, when "xts(ecb(aes-generic))" is instantiated and tested during the comparison tests for "xts-aes-aesni", the "xts" template allocates an "aes" crypto_cipher for encrypting tweaks. This resolves to "aes-aesni". (Getting "aes-aesni" instead of "aes-generic" here is a bit weird, but it's apparently intended.) Due to the above-mentioned commit, the testing of "aes-aesni", and the finalization of its registration, now happens at this point instead of before. At the end of that, crypto_remove_spawns() unregisters all algorithm instances that depend on a lower-priority "aes" implementation such as "aes-generic" but that do not depend on "aes-aesni". However, because "xts" does not use the crypto_spawn mechanism for its "aes", its dependency on "aes-aesni" is not recognized by crypto_remove_spawns(). Thus, crypto_remove_spawns() unexpectedly unregisters "xts(ecb(aes-generic))". Fix this issue by making the "xts" template use the crypto_spawn mechanism for its "aes" dependency, like what other templates do. Note, this fix could be applied as far back as commit f1c131b45410 ("crypto: xts - Convert to skcipher"). However, the issue only got exposed by the much more recent changes to how the crypto API runs the self-tests, so there should be no need to backport this to very old kernels. Also, an alternative fix would be to flip the list iteration order in crypto_start_tests() to restore the original testing order. I'm thinking we should do that too, since the original order seems more natural, but it shouldn't be relied on for correctness. Fixes: adad556efcdd ("crypto: api - Fix built-in testing dependency failures") Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu --- crypto/xts.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/crypto/xts.c b/crypto/xts.c index 9237b14333672..672e1a3f0b0c9 100644 --- a/crypto/xts.c +++ b/crypto/xts.c @@ -28,7 +28,7 @@ struct xts_tfm_ctx { struct xts_instance_ctx { struct crypto_skcipher_spawn spawn; - char name[CRYPTO_MAX_ALG_NAME]; + struct crypto_cipher_spawn tweak_spawn; }; struct xts_request_ctx { @@ -306,7 +306,7 @@ static int xts_init_tfm(struct crypto_skcipher *tfm) ctx->child = child; - tweak = crypto_alloc_cipher(ictx->name, 0, 0); + tweak = crypto_spawn_cipher(&ictx->tweak_spawn); if (IS_ERR(tweak)) { crypto_free_skcipher(ctx->child); return PTR_ERR(tweak); @@ -333,12 +333,14 @@ static void xts_free_instance(struct skcipher_instance *inst) struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst); crypto_drop_skcipher(&ictx->spawn); + crypto_drop_cipher(&ictx->tweak_spawn); kfree(inst); } static int xts_create(struct crypto_template *tmpl, struct rtattr **tb) { struct skcipher_alg_common *alg; + char name[CRYPTO_MAX_ALG_NAME]; struct skcipher_instance *inst; struct xts_instance_ctx *ctx; const char *cipher_name; @@ -363,13 +365,13 @@ static int xts_create(struct crypto_template *tmpl, struct rtattr **tb) cipher_name, 0, mask); if (err == -ENOENT) { err = -ENAMETOOLONG; - if (snprintf(ctx->name, CRYPTO_MAX_ALG_NAME, "ecb(%s)", + if (snprintf(name, CRYPTO_MAX_ALG_NAME, "ecb(%s)", cipher_name) >= CRYPTO_MAX_ALG_NAME) goto err_free_inst; err = crypto_grab_skcipher(&ctx->spawn, skcipher_crypto_instance(inst), - ctx->name, 0, mask); + name, 0, mask); } if (err) @@ -398,23 +400,28 @@ static int xts_create(struct crypto_template *tmpl, struct rtattr **tb) if (!strncmp(cipher_name, "ecb(", 4)) { int len; - len = strscpy(ctx->name, cipher_name + 4, sizeof(ctx->name)); + len = strscpy(name, cipher_name + 4, sizeof(name)); if (len < 2) goto err_free_inst; - if (ctx->name[len - 1] != ')') + if (name[len - 1] != ')') goto err_free_inst; - ctx->name[len - 1] = 0; + name[len - 1] = 0; if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, - "xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME) { + "xts(%s)", name) >= CRYPTO_MAX_ALG_NAME) { err = -ENAMETOOLONG; goto err_free_inst; } } else goto err_free_inst; + err = crypto_grab_cipher(&ctx->tweak_spawn, + skcipher_crypto_instance(inst), name, 0, mask); + if (err) + goto err_free_inst; + inst->alg.base.cra_priority = alg->base.cra_priority; inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE; inst->alg.base.cra_alignmask = alg->base.cra_alignmask | -- 2.39.2