[PATCH v5 02/10] IMA: Added keyrings= option in IMA policy to only measure keys added to the specifi

[Lakshmi Ramasubramanian <nramas@linux.microsoft.com>]

IMA policy needs to support measuring only those keys linked to
a specific set of keyrings.

This patch defines a new IMA policy option namely "keyrings=" that
can be used to specify a set of keyrings. If this option is specified
in the policy for func=KEYRING_CHECK then only the keys linked to
the keyrings given in "keyrings=" option are measured.

If "keyrings=" option is not specified for func=KEYRING_CHECK then
all keys are measured.

Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
---
 Documentation/ABI/testing/ima_policy | 10 +++++++++-
 security/integrity/ima/ima_policy.c  |  2 ++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index 341df49b5ad1..be2874fa3928 100644
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -25,7 +25,7 @@ Description:
 			lsm:	[[subj_user=] [subj_role=] [subj_type=]
 				 [obj_user=] [obj_role=] [obj_type=]]
 			option:	[[appraise_type=]] [template=] [permit_directio]
-				[appraise_flag=]
+				[appraise_flag=] [keyrings=]
 		base: 	func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK][MODULE_CHECK]
 				[FIRMWARE_CHECK]
 				[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
@@ -43,6 +43,9 @@ Description:
 			appraise_flag:= [check_blacklist]
 			Currently, blacklist check is only for files signed with appended
 			signature.
+			keyrings:= list of keyrings
+			(eg, .builtin_trusted_keys|.ima). Only valid
+			when action is "measure" and func is KEYRING_CHECK.
 			template:= name of a defined IMA template type
 			(eg, ima-ng). Only valid when action is "measure".
 			pcr:= decimal value
@@ -119,3 +122,8 @@ Description:
 		all keys:
 
 			measure func=KEYRING_CHECK
+
+		Example of measure rule using KEYRING_CHECK to only measure
+		keys added to .builtin_trusted_keys or .ima keyring:
+
+			measure func=KEYRING_CHECK keyrings=.builtin_trusted_keys|.ima
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 9ca32ffaaa9d..a0f7ffa80736 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -34,6 +34,7 @@
 #define IMA_EUID	0x0080
 #define IMA_PCR		0x0100
 #define IMA_FSNAME	0x0200
+#define IMA_KEYRINGS	0x0400
 
 #define UNKNOWN		0
 #define MEASURE		0x0001	/* same as IMA_MEASURE */
@@ -79,6 +80,7 @@ struct ima_rule_entry {
 		int type;	/* audit type */
 	} lsm[MAX_LSM_RULES];
 	char *fsname;
+	char *keyrings; /* Measure keys added to these keyrings */
 	struct ima_template_desc *template;
 };
 
-- 
2.17.1