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authorMatthew Garrett <mjg59@google.com>2018-06-08 14:57:42 -0700
committerMimi Zohar <zohar@linux.vnet.ibm.com>2018-07-18 07:27:22 -0400
commite2861fa71641c6414831d628a1f4f793b6562580 (patch)
treee832d4eac8fb33e2838a76cc9457bd3c2d6a2065 /security/integrity
parentac2409a521f7ec5978fd582567398d19f4a2fdbd (diff)
downloadlinux-stericsson-e2861fa71641c6414831d628a1f4f793b6562580.tar.gz
evm: Don't deadlock if a crypto algorithm is unavailable
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>
Diffstat (limited to 'security/integrity')
-rw-r--r--security/integrity/evm/evm_crypto.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index b60524310855..c20e3142b541 100644
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -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);