Re: [PATCH v3 07/12] ima: Fail rule parsing when appraise_flag=blacklist is unsupportable
From: Mimi Zohar <zohar@linux.ibm.com>
Date: 2020-07-16 18:15:04
Also in:
linux-integrity, lkml
On Thu, 2020-07-09 at 01:19 -0500, Tyler Hicks wrote:
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.
The code looks correct, but this patch description could be written at a higher level. Perhaps it just needs to be prefixed with something like this: 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, ... Mimi
Fixes: 273df864cf74 ("ima: Check against blacklisted hashes for files with modsig")
Signed-off-by: Tyler Hicks <redacted>
Cc: Nayna Jain <nayna@linux.ibm.com>quoted hunk ↗ jump to hunk
--- * v3 - New patch security/integrity/ima/ima_policy.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 81da02071d41..9842e2e0bc6d 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; }@@ -1371,8 +1376,14 @@ 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; break; case Opt_permit_directio: