From 2eb27c11937ee9984c04b75d213a737291c5f58c Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Thu, 9 Jul 2020 23:20:39 -0700 Subject: [PATCH] crypto: algapi - add NEED_FALLBACK to INHERITED_FLAGS CRYPTO_ALG_NEED_FALLBACK is handled inconsistently. When it's requested to be clear, some templates propagate that request to child algorithms, while others don't. It's apparently desired for NEED_FALLBACK to be propagated, to avoid deadlocks where a module tries to load itself while it's being initialized, and to avoid unnecessarily complex fallback chains where we have e.g. cbc-aes-$driver falling back to cbc(aes-$driver) where aes-$driver itself falls back to aes-generic, instead of cbc-aes-$driver simply falling back to cbc(aes-generic). There have been a number of fixes to this effect: commit 89027579bc6c ("crypto: xts - Propagate NEED_FALLBACK bit") commit d2c2a85cfe82 ("crypto: ctr - Propagate NEED_FALLBACK bit") commit e6c2e65c70a6 ("crypto: cbc - Propagate NEED_FALLBACK bit") But it seems that other templates can have the same problems too. To avoid this whack-a-mole, just add NEED_FALLBACK to INHERITED_FLAGS so that it's always inherited. Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu --- crypto/ctr.c | 2 -- crypto/skcipher.c | 2 -- crypto/xts.c | 2 -- include/crypto/algapi.h | 3 ++- include/linux/crypto.h | 4 ++-- 5 files changed, 4 insertions(+), 9 deletions(-) diff --git a/crypto/ctr.c b/crypto/ctr.c index ae8d88c..c39fcff 100644 --- a/crypto/ctr.c +++ b/crypto/ctr.c @@ -265,8 +265,6 @@ static int crypto_rfc3686_create(struct crypto_template *tmpl, err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask); if (err) return err; - mask |= crypto_requires_off(crypto_get_attr_type(tb), - CRYPTO_ALG_NEED_FALLBACK); inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); if (!inst) diff --git a/crypto/skcipher.c b/crypto/skcipher.c index 3b93a74..467af52 100644 --- a/crypto/skcipher.c +++ b/crypto/skcipher.c @@ -943,8 +943,6 @@ struct skcipher_instance *skcipher_alloc_instance_simple( err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask); if (err) return ERR_PTR(err); - mask |= crypto_requires_off(crypto_get_attr_type(tb), - CRYPTO_ALG_NEED_FALLBACK); inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); if (!inst) diff --git a/crypto/xts.c b/crypto/xts.c index 35a3061..9a7adab 100644 --- a/crypto/xts.c +++ b/crypto/xts.c @@ -340,8 +340,6 @@ static int create(struct crypto_template *tmpl, struct rtattr **tb) err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask); if (err) return err; - mask |= crypto_requires_off(crypto_get_attr_type(tb), - CRYPTO_ALG_NEED_FALLBACK); cipher_name = crypto_attr_alg_name(tb[1]); if (IS_ERR(cipher_name)) diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h index da64c37..22cf4d8 100644 --- a/include/crypto/algapi.h +++ b/include/crypto/algapi.h @@ -245,7 +245,8 @@ static inline u32 crypto_requires_off(struct crypto_attr_type *algt, u32 off) * template), these are the flags that should always be set on the "outer" * algorithm if any "inner" algorithm has them set. */ -#define CRYPTO_ALG_INHERITED_FLAGS CRYPTO_ALG_ASYNC +#define CRYPTO_ALG_INHERITED_FLAGS \ + (CRYPTO_ALG_ASYNC | CRYPTO_ALG_NEED_FALLBACK) /* * Given the type and mask that specify the flags restrictions on a template diff --git a/include/linux/crypto.h b/include/linux/crypto.h index 7cd2d00..f73f0b5 100644 --- a/include/linux/crypto.h +++ b/include/linux/crypto.h @@ -60,8 +60,8 @@ #define CRYPTO_ALG_ASYNC 0x00000080 /* - * Set this bit if and only if the algorithm requires another algorithm of - * the same type to handle corner cases. + * Set if the algorithm (or an algorithm which it uses) requires another + * algorithm of the same type to handle corner cases. */ #define CRYPTO_ALG_NEED_FALLBACK 0x00000100 -- 2.7.4