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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Nayna Jain <nayna@linux.ibm.com>,
        Tyler Hicks <tyhicks@linux.microsoft.com>,
        Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
        Mimi Zohar <zohar@linux.ibm.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.9 222/757] ima: Fail rule parsing when asymmetric key measurement isnt supportable
Date:   Tue, 27 Oct 2020 14:47:52 +0100
Message-Id: <20201027135501.034151230@linuxfoundation.org>
In-Reply-To: <20201027135450.497324313@linuxfoundation.org>
References: <20201027135450.497324313@linuxfoundation.org>
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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