From: Tyler Hicks tyhicks@linux.microsoft.com
[ Upstream commit db2045f5892a9db7354442bf77f9b03b50ff9ee1 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- security/integrity/ima/ima_policy.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index a3d72342408ad..a77e0b34e72f7 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;