tree 45316853ff7c76f3cc9958dc9c865f566e3a9515
parent 23bd97eaebc55d5eef9d3cd41e3bd6189a0e9dd6
author Matthew Garrett <mjg59@google.com> 1528495062 -0700
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1537943797 +0200

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 <mjg59@google.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>