linux-kernel - [PATCH v6 1/3] IMA: Add KEY

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Message-Id: <20191113184658.2862-2-nramas@linux.microsoft.com>
Date:   Wed, 13 Nov 2019 10:46:56 -0800
From:   Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
To:     zohar@...ux.ibm.com, dhowells@...hat.com,
        matthewgarrett@...gle.com, sashal@...nel.org,
        jamorris@...ux.microsoft.com, linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, keyrings@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v6 1/3] IMA: Add KEY_CHECK func to measure keys

Measure keys loaded onto any keyring.

This patch defines a new IMA policy func namely KEY_CHECK to
measure keys. Updated ima_match_rules() to check for KEY_CHECK
and ima_parse_rule() to handle KEY_CHECK.

Signed-off-by: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
---
 Documentation/ABI/testing/ima_policy | 6 +++++-
 security/integrity/ima/ima.h         | 1 +
 security/integrity/ima/ima_main.c    | 7 +++++++
 security/integrity/ima/ima_policy.c  | 4 +++-
 4 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index 29aaedf33246..066d32797500 100644
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -29,7 +29,7 @@ Description:
 		base: 	func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK][MODULE_CHECK]
 				[FIRMWARE_CHECK]
 				[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
-				[KEXEC_CMDLINE]
+				[KEXEC_CMDLINE] [KEY_CHECK]
 			mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
 			       [[^]MAY_EXEC]
 			fsmagic:= hex value
@@ -113,3 +113,7 @@ Description:
 		Example of appraise rule allowing modsig appended signatures:
 
 			appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig
+
+		Example of measure rule using KEY_CHECK to measure all keys:
+
+			measure func=KEY_CHECK
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index df4ca482fb53..fe6c698617bd 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -193,6 +193,7 @@ static inline unsigned long ima_hash_key(u8 *digest)
 	hook(KEXEC_INITRAMFS_CHECK)	\
 	hook(POLICY_CHECK)		\
 	hook(KEXEC_CMDLINE)		\
+	hook(KEY_CHECK)			\
 	hook(MAX_CHECK)
 #define __ima_hook_enumify(ENUM)	ENUM,
 
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index d7e987baf127..12684e8d7124 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -655,6 +655,13 @@ void process_buffer_measurement(const void *buf, int size,
 	int action = 0;
 	u32 secid;
 
+	/*
+	 * If IMA is not yet initialized or IMA policy is empty
+	 * then there is no need to measure.
+	 */
+	if (!ima_policy_flag)
+		return;
+
 	/*
 	 * Both LSM hooks and auxilary based buffer measurements are
 	 * based on policy.  To avoid code duplication, differentiate
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index f19a895ad7cd..1525a28fd705 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -373,7 +373,7 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
 {
 	int i;
 
-	if (func == KEXEC_CMDLINE) {
+	if ((func == KEXEC_CMDLINE) || (func == KEY_CHECK)) {
 		if ((rule->flags & IMA_FUNC) && (rule->func == func))
 			return true;
 		return false;
@@ -997,6 +997,8 @@ 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)
+				entry->func = KEY_CHECK;
 			else
 				result = -EINVAL;
 			if (!result)
-- 
2.17.1