From: Tushar Sugandhi <tusharsu@linux.microsoft.com>
To: zohar@linux.ibm.com, stephen.smalley.work@gmail.com,
casey@schaufler-ca.com, agk@redhat.com, snitzer@redhat.com,
gmazyland@gmail.com, paul@paul-moore.com
Cc: tyhicks@linux.microsoft.com, sashal@kernel.org,
jmorris@namei.org, nramas@linux.microsoft.com,
linux-integrity@vger.kernel.org, selinux@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, dm-devel@redhat.com
Subject: [PATCH v8 4/8] IMA: add policy rule to measure critical data
Date: Fri, 11 Dec 2020 15:58:03 -0800 [thread overview]
Message-ID: <20201211235807.30815-5-tusharsu@linux.microsoft.com> (raw)
In-Reply-To: <20201211235807.30815-1-tusharsu@linux.microsoft.com>
A new IMA policy rule is needed for the IMA hook
ima_measure_critical_data() and the corresponding func CRITICAL_DATA for
measuring the input buffer. The policy rule should ensure the buffer
would get measured only when the policy rule allows the action. The
policy rule should also support the necessary constraints (flags etc.)
for integrity critical buffer data measurements.
Add a policy rule to define the constraints for restricting integrity
critical data measurements.
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
---
Documentation/ABI/testing/ima_policy | 2 +-
security/integrity/ima/ima_policy.c | 34 ++++++++++++++++++++++++----
2 files changed, 31 insertions(+), 5 deletions(-)
diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index e35263f97fc1..6ec7daa87cba 100644
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -32,7 +32,7 @@ Description:
func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK]MODULE_CHECK]
[FIRMWARE_CHECK]
[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
- [KEXEC_CMDLINE] [KEY_CHECK]
+ [KEXEC_CMDLINE] [KEY_CHECK] [CRITICAL_DATA]
mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
[[^]MAY_EXEC]
fsmagic:= hex value
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index a09d1a41a290..07116ff35c25 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -85,6 +85,7 @@ struct ima_rule_entry {
} lsm[MAX_LSM_RULES];
char *fsname;
struct ima_rule_opt_list *keyrings; /* Measure keys added to these keyrings */
+ struct ima_rule_opt_list *data_source; /* Measure data from this source */
struct ima_template_desc *template;
};
@@ -479,6 +480,12 @@ static bool ima_match_rule_data(struct ima_rule_entry *rule,
opt_list = rule->keyrings;
break;
+ case CRITICAL_DATA:
+ if (!rule->data_source)
+ return true;
+
+ opt_list = rule->data_source;
+ break;
default:
return false;
}
@@ -515,13 +522,19 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
{
int i;
- if (func == KEY_CHECK) {
- return (rule->flags & IMA_FUNC) && (rule->func == func) &&
- ima_match_rule_data(rule, func_data, cred);
- }
if ((rule->flags & IMA_FUNC) &&
(rule->func != func && func != POST_SETATTR))
return false;
+
+ switch (func) {
+ case KEY_CHECK:
+ case CRITICAL_DATA:
+ return ((rule->func == func) &&
+ ima_match_rule_data(rule, func_data, cred));
+ default:
+ break;
+ }
+
if ((rule->flags & IMA_MASK) &&
(rule->mask != mask && func != POST_SETATTR))
return false;
@@ -1116,6 +1129,17 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
if (ima_rule_contains_lsm_cond(entry))
return false;
+ break;
+ case CRITICAL_DATA:
+ if (entry->action & ~(MEASURE | DONT_MEASURE))
+ return false;
+
+ if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR))
+ return false;
+
+ if (ima_rule_contains_lsm_cond(entry))
+ return false;
+
break;
default:
return false;
@@ -1248,6 +1272,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
else if (IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) &&
strcmp(args[0].from, "KEY_CHECK") == 0)
entry->func = KEY_CHECK;
+ else if (strcmp(args[0].from, "CRITICAL_DATA") == 0)
+ entry->func = CRITICAL_DATA;
else
result = -EINVAL;
if (!result)
--
2.17.1
next prev parent reply other threads:[~2020-12-12 0:09 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-11 23:57 [PATCH v8 0/8] IMA: support for measuring kernel integrity critical data Tushar Sugandhi
2020-12-11 23:58 ` [PATCH v8 1/8] IMA: generalize keyring specific measurement constructs Tushar Sugandhi
2020-12-12 0:08 ` Tyler Hicks
2020-12-11 23:58 ` [PATCH v8 2/8] IMA: add support to measure buffer data hash Tushar Sugandhi
2020-12-12 0:09 ` Tyler Hicks
2020-12-11 23:58 ` [PATCH v8 3/8] IMA: define a hook to measure kernel integrity critical data Tushar Sugandhi
2020-12-12 0:13 ` Tyler Hicks
2020-12-11 23:58 ` Tushar Sugandhi [this message]
2020-12-12 0:25 ` [PATCH v8 4/8] IMA: add policy rule to measure " Tyler Hicks
2020-12-12 1:17 ` Tushar Sugandhi
2020-12-12 14:47 ` Tyler Hicks
2020-12-12 17:34 ` Tushar Sugandhi
2020-12-11 23:58 ` [PATCH v8 5/8] IMA: limit critical data measurement based on a label Tushar Sugandhi
2020-12-11 23:58 ` [PATCH v8 6/8] IMA: extend critical data hook to limit the " Tushar Sugandhi
2020-12-11 23:58 ` [PATCH v8 7/8] IMA: define a builtin critical data measurement policy Tushar Sugandhi
2020-12-11 23:58 ` [PATCH v8 8/8] selinux: include a consumer of the new IMA critical data hook Tushar Sugandhi
2020-12-12 0:32 ` Tyler Hicks
2020-12-12 0:33 ` Lakshmi Ramasubramanian
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