Re: [PATCH v3 06/12] ima: Fail rule parsing when the KEY_CHECK hook is combined with an invalid cond

On 2020-07-17 14:56:46, Nayna wrote:

quoted

On 7/9/20 2:19 AM, Tyler Hicks wrote:

quoted

The KEY_CHECK function only supports the uid, pcr, and keyrings
conditionals. Make this clear at policy load so that IMA policy authors
don't assume that other conditionals are supported.

Fixes: 5808611cccb2 ("IMA: Add KEY_CHECK func to measure keys")
Signed-off-by: Tyler Hicks <redacted>
Reviewed-by: Lakshmi Ramasubramanian <redacted>
---

* v3
   - Added Lakshmi's Reviewed-by
   - Adjust for the indentation change introduced in patch #4
* v2
   - No change

  security/integrity/ima/ima_policy.c | 7 +++++++
  1 file changed, 7 insertions(+)

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 1c64bd6f1728..81da02071d41 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c

@@ -1023,6 +1023,13 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
  		if (entry->action & ~(MEASURE | DONT_MEASURE))
  			return false;

+		if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR |
+				     IMA_KEYRINGS))
+			return false;
+
+		if (ima_rule_contains_lsm_cond(entry))
+			return false;
+
  		break;
  	default:
  		return false;

Should there be a check for IMA_MEASURE_ASYMMETRIC_KEYS in Opt_keyrings in
ima_parse_rule() to return immediately if not enabled ?

I didn't notice that "keyrings=" could be disabled at build time. I
think you're right that something like what I have below would be a good idea.

@Lakshmi, do you agree?

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 81da02071d41..bd687560f88e 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c

@@ -1212,6 +1212,11 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 		case Opt_keyrings:
 			ima_log_string(ab, "keyrings", args[0].from);
 
+			if (!IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS)) {
+				result = -EINVAL;
+				break;
+			}
+
 			keyrings_len = strlen(args[0].from) + 1;
 
 			if ((entry->keyrings) ||