[lkml]   [2020]   [Jul]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH v3 05/12] 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

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 <>
Reviewed-by: Mimi Zohar <>
Reviewed-by: Lakshmi Ramasubramanian <>

* v3
- Adjust for the indentation change introduced in patch #4
- Added Lakshmi's Reviewed-by
* v2
- Added Mimi's Reviewed-by

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 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() */
+ 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;
if (entry->action & ~(MEASURE | DONT_MEASURE))
return false;
 \ /
  Last update: 2020-07-09 08:20    [W:0.149 / U:0.388 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site