xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

evm: Don't deadlock if a crypto algorithm is unavailable

Browse Source 
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 <mjg59@google.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
This commit is contained in:
Matthew Garrett
2018-06-08 14:57:42 -07:00
committed by Mimi Zohar
parent ac2409a521
commit e2861fa716
3 changed files with 8 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
security/integrity/evm/evm_crypto.c
View File

@@ -97,7 +97,8 @@ static struct shash_desc *init_desc(char type)
mutex_lock(&mutex);
if (*tfm)
goto out;
*tfm = crypto_alloc_shash(algo, 0, CRYPTO_ALG_ASYNC);
*tfm = crypto_alloc_shash(algo, 0,
CRYPTO_ALG_ASYNC | CRYPTO_NOLOAD);
if (IS_ERR(*tfm)) {
rc = PTR_ERR(*tfm);
pr_err("Can not allocate %s (reason: %ld)\n", algo, rc);