From fbb6cda44190d72aa5199d728797aabc6d2ed816 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Thu, 9 Jul 2020 23:20:40 -0700 Subject: crypto: algapi - introduce the flag CRYPTO_ALG_ALLOCATES_MEMORY Introduce a new algorithm flag CRYPTO_ALG_ALLOCATES_MEMORY. If this flag is set, then the driver allocates memory in its request routine. Such drivers are not suitable for disk encryption because GFP_ATOMIC allocation can fail anytime (causing random I/O errors) and GFP_KERNEL allocation can recurse into the block layer, causing a deadlock. For now, this flag is only implemented for some algorithm types. We also assume some usage constraints for it to be meaningful, since there are lots of edge cases the crypto API allows (e.g., misaligned or fragmented scatterlists) that mean that nearly any crypto algorithm can allocate memory in some case. See the comment for details. Also add this flag to CRYPTO_ALG_INHERITED_FLAGS so that when a template is instantiated, this flag is set on the template instance if it is set on any algorithm the instance uses. Based on a patch by Mikulas Patocka (https://lore.kernel.org/r/alpine.LRH.2.02.2006301414580.30526@file01.intranet.prod.int.rdu2.redhat.com). Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu --- include/crypto/algapi.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/crypto') diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h index 22cf4d80959f..143d884d65c7 100644 --- a/include/crypto/algapi.h +++ b/include/crypto/algapi.h @@ -246,7 +246,8 @@ static inline u32 crypto_requires_off(struct crypto_attr_type *algt, u32 off) * algorithm if any "inner" algorithm has them set. */ #define CRYPTO_ALG_INHERITED_FLAGS \ - (CRYPTO_ALG_ASYNC | CRYPTO_ALG_NEED_FALLBACK) + (CRYPTO_ALG_ASYNC | CRYPTO_ALG_NEED_FALLBACK | \ + CRYPTO_ALG_ALLOCATES_MEMORY) /* * Given the type and mask that specify the flags restrictions on a template -- cgit v1.2.3