[PATCH 5.9 222/757] ima: Fail rule parsing when asymmetric key measurement isnt supportable

Greg Kroah-Hartman
2020-10-27T15:58:41Z

From: Tyler Hicks <tyhicks@linux.microsoft.com>

[ Upstream commit 48ce1ddce16b0d1e3ff948da40a0d5125a4ee1a0 ]

Measuring keys is currently only supported for asymmetric keys. In the
future, this might change.

For now, the "func=KEY_CHECK" and "keyrings=" options are only
appropriate when CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS is enabled. Make
this clear at policy load so that IMA policy authors don't assume that
these policy language constructs are supported.

Fixes: 2b60c0ecedf8 ("IMA: Read keyrings= option from the IMA policy")
Fixes: 5808611cccb2 ("IMA: Add KEY_CHECK func to measure keys")
Suggested-by: Nayna Jain <nayna@linux.ibm.com>
Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Reviewed-by: Nayna Jain <nayna@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
security/integrity/ima/ima_policy.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 9354e7cf4a09f..4a7a4b6bf79b2 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -1233,7 +1233,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
entry->func = POLICY_CHECK;
else if (strcmp(args[0].from, "KEXEC_CMDLINE") == 0)
entry->func = KEXEC_CMDLINE;
- else if (strcmp(args[0].from, "KEY_CHECK") == 0)
+ else if (IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) &&
+ strcmp(args[0].from, "KEY_CHECK") == 0)
entry->func = KEY_CHECK;
else
result = -EINVAL;
@@ -1290,7 +1291,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
case Opt_keyrings:
ima_log_string(ab, "keyrings", args[0].from);

- if (entry->keyrings) {
+ if (!IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) ||
+ entry->keyrings) {
result = -EINVAL;
break;
}
--
2.25.1