[PATCH v4 03/10] IMA: Added keyrings= option in IMA policy to only measure keys added to the specified keyrings.

Lakshmi Ramasubramanian
2019-11-06T19:02:07Z

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 4344b7354fc5..4d68ad8ed91c 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