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authorTyler Hicks <tyhicks@linux.microsoft.com>2020-07-09 01:19:06 -0500
committerMimi Zohar <zohar@linux.ibm.com>2020-07-20 13:06:26 -0400
commit5f3e92657bbfb63ad3109433d843c89996114b03 (patch)
treeac5c817f82eff72c557ebfa6ee21221bedd0ad77 /security
parenteb624fe214a2e156ddafd9868377cf91499f789d (diff)
downloadlwn-5f3e92657bbfb63ad3109433d843c89996114b03.tar.gz
lwn-5f3e92657bbfb63ad3109433d843c89996114b03.zip
ima: Fail rule parsing when appraise_flag=blacklist is unsupportable
Verifying that a file hash is not blacklisted is currently only supported for files with appended signatures (modsig). In the future, this might change. For now, the "appraise_flag" option is only appropriate for appraise actions and its "blacklist" value is only appropriate when CONFIG_IMA_APPRAISE_MODSIG is enabled and "appraise_flag=blacklist" is only appropriate when "appraise_type=imasig|modsig" is also present. Make this clear at policy load so that IMA policy authors don't assume that other uses of "appraise_flag=blacklist" are supported. Fixes: 273df864cf74 ("ima: Check against blacklisted hashes for files with modsig") Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com> Reivewed-by: Nayna Jain <nayna@linux.ibm.com> Tested-by: Nayna Jain <nayna@linux.ibm.com> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Diffstat (limited to 'security')
-rw-r--r--security/integrity/ima/ima_policy.c15
1 files changed, 14 insertions, 1 deletions
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 81da02071d41..cf3ddb38dfa8 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -1035,6 +1035,11 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
return false;
}
+ /* Ensure that combinations of flags are compatible with each other */
+ if (entry->flags & IMA_CHECK_BLACKLIST &&
+ !(entry->flags & IMA_MODSIG_ALLOWED))
+ return false;
+
return true;
}
@@ -1371,9 +1376,17 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
result = -EINVAL;
break;
case Opt_appraise_flag:
+ if (entry->action != APPRAISE) {
+ result = -EINVAL;
+ break;
+ }
+
ima_log_string(ab, "appraise_flag", args[0].from);
- if (strstr(args[0].from, "blacklist"))
+ if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) &&
+ strstr(args[0].from, "blacklist"))
entry->flags |= IMA_CHECK_BLACKLIST;
+ else
+ result = -EINVAL;
break;
case Opt_permit_directio:
entry->flags |= IMA_PERMIT_DIRECTIO;