From eddbab1384841db30b270bc791ad623ad0cd5a38 Mon Sep 17 00:00:00 2001 From: Matthew Garrett Date: Fri, 8 Jun 2018 14:57:42 -0700 Subject: evm: Don't deadlock if a crypto algorithm is unavailable [ Upstream commit e2861fa71641c6414831d628a1f4f793b6562580 ] When EVM attempts to appraise a file signed with a crypto algorithm the kernel doesn't have support for, it will cause the kernel to trigger a module load. If the EVM policy includes appraisal of kernel modules this will in turn call back into EVM - since EVM is holding a lock until the crypto initialisation is complete, this triggers a deadlock. Add a CRYPTO_NOLOAD flag and skip module loading if it's set, and add that flag in the EVM case in order to fail gracefully with an error message instead of deadlocking. Signed-off-by: Matthew Garrett Acked-by: Herbert Xu Signed-off-by: Mimi Zohar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- include/linux/crypto.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include') diff --git a/include/linux/crypto.h b/include/linux/crypto.h index 8edb3ba6f640..9de26962338e 100644 --- a/include/linux/crypto.h +++ b/include/linux/crypto.h @@ -108,6 +108,11 @@ */ #define CRYPTO_ALG_OPTIONAL_KEY 0x00004000 +/* + * Don't trigger module loading + */ +#define CRYPTO_NOLOAD 0x00008000 + /* * Transform masks and values (for crt_flags). */ -- cgit v1.2.3