tree e832d4eac8fb33e2838a76cc9457bd3c2d6a2065
parent ac2409a521f7ec5978fd582567398d19f4a2fdbd
author Matthew Garrett <mjg59@google.com> 1528495062 -0700
committer Mimi Zohar <zohar@linux.vnet.ibm.com> 1531913242 -0400

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>