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authorTyler Hicks <tyhicks@linux.microsoft.com>2020-07-09 01:19:04 -0500
committerMimi Zohar <zohar@linux.ibm.com>2020-07-16 21:53:55 -0400
commitdb2045f5892a9db7354442bf77f9b03b50ff9ee1 (patch)
tree071449c083f538a668b58ba87788dbe2139abd36 /security
parent712183437ebebc89cd086ef96cf9a521fd97fd09 (diff)
ima: Fail rule parsing when the KEXEC_CMDLINE hook is combined with an invalid cond
The KEXEC_CMDLINE hook function only supports the pcr conditional. Make this clear at policy load so that IMA policy authors don't assume that other conditionals are supported. Since KEXEC_CMDLINE's inception, ima_match_rules() has always returned true on any loaded KEXEC_CMDLINE rule without any consideration for other conditionals present in the rule. Make it clear that pcr is the only supported KEXEC_CMDLINE conditional by returning an error during policy load. An example of why this is a problem can be explained with the following rule: dont_measure func=KEXEC_CMDLINE obj_type=foo_t An IMA policy author would have assumed that rule is valid because the parser accepted it but the result was that measurements for all KEXEC_CMDLINE operations would be disabled. Fixes: b0935123a183 ("IMA: Define a new hook to measure the kexec boot command line arguments") Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com> Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Diffstat (limited to 'security')
-rw-r--r--security/integrity/ima/ima_policy.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 40c28f1a6a5a..1c64bd6f1728 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -343,6 +343,17 @@ static int ima_lsm_update_rule(struct ima_rule_entry *entry)
return 0;
}
+static bool ima_rule_contains_lsm_cond(struct ima_rule_entry *entry)
+{
+ int i;
+
+ for (i = 0; i < MAX_LSM_RULES; i++)
+ if (entry->lsm[i].args_p)
+ return true;
+
+ return false;
+}
+
/*
* The LSM policy can be reloaded, leaving the IMA LSM based rules referring
* to the old, stale LSM policy. Update the IMA LSM based rules to reflect
@@ -998,6 +1009,16 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
/* Validation of these hook functions is in ima_parse_rule() */
break;
case KEXEC_CMDLINE:
+ if (entry->action & ~(MEASURE | DONT_MEASURE))
+ return false;
+
+ if (entry->flags & ~(IMA_FUNC | IMA_PCR))
+ return false;
+
+ if (ima_rule_contains_lsm_cond(entry))
+ return false;
+
+ break;
case KEY_CHECK:
if (entry->action & ~(MEASURE | DONT_MEASURE))
return false;