From: GUO Zihua guozihua@huawei.com
[ Upstream commit c7423dbdbc9ecef7fff5239d144cad4b9887f4de ]
IMA relies on the blocking LSM policy notifier callback to update the LSM based IMA policy rules.
When SELinux update its policies, IMA would be notified and starts updating all its lsm rules one-by-one. During this time, -ESTALE would be returned by ima_filter_rule_match() if it is called with a LSM rule that has not yet been updated. In ima_match_rules(), -ESTALE is not handled, and the LSM rule is considered a match, causing extra files to be measured by IMA.
Fix it by re-initializing a temporary rule if -ESTALE is returned by ima_filter_rule_match(). The origin rule in the rule list would be updated by the LSM policy notifier callback.
Fixes: b16942455193 ("ima: use the lsm policy update notifier") Signed-off-by: GUO Zihua guozihua@huawei.com Reviewed-by: Roberto Sassu roberto.sassu@huawei.com Signed-off-by: Mimi Zohar zohar@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- security/integrity/ima/ima_policy.c | 41 ++++++++++++++++++++++------- 1 file changed, 32 insertions(+), 9 deletions(-)
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index a8802b8da946..bb3707160b01 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -549,6 +549,9 @@ static bool ima_match_rules(struct ima_rule_entry *rule, const char *func_data) { int i; + bool result = false; + struct ima_rule_entry *lsm_rule = rule; + bool rule_reinitialized = false;
if ((rule->flags & IMA_FUNC) && (rule->func != func && func != POST_SETATTR)) @@ -610,35 +613,55 @@ static bool ima_match_rules(struct ima_rule_entry *rule, int rc = 0; u32 osid;
- if (!rule->lsm[i].rule) { - if (!rule->lsm[i].args_p) + if (!lsm_rule->lsm[i].rule) { + if (!lsm_rule->lsm[i].args_p) continue; else return false; } + +retry: switch (i) { case LSM_OBJ_USER: case LSM_OBJ_ROLE: case LSM_OBJ_TYPE: security_inode_getsecid(inode, &osid); - rc = ima_filter_rule_match(osid, rule->lsm[i].type, + rc = ima_filter_rule_match(osid, lsm_rule->lsm[i].type, Audit_equal, - rule->lsm[i].rule); + lsm_rule->lsm[i].rule); break; case LSM_SUBJ_USER: case LSM_SUBJ_ROLE: case LSM_SUBJ_TYPE: - rc = ima_filter_rule_match(secid, rule->lsm[i].type, + rc = ima_filter_rule_match(secid, lsm_rule->lsm[i].type, Audit_equal, - rule->lsm[i].rule); + lsm_rule->lsm[i].rule); break; default: break; } - if (!rc) - return false; + + if (rc == -ESTALE && !rule_reinitialized) { + lsm_rule = ima_lsm_copy_rule(rule); + if (lsm_rule) { + rule_reinitialized = true; + goto retry; + } + } + if (!rc) { + result = false; + goto out; + } } - return true; + result = true; + +out: + if (rule_reinitialized) { + for (i = 0; i < MAX_LSM_RULES; i++) + ima_filter_rule_free(lsm_rule->lsm[i].rule); + kfree(lsm_rule); + } + return result; }
/*