[PATCH] ima: ima/lsm policy rule loading logic bug fixes

[Janne Karhunen <janne.karhunen@xxxxxxxxx>]

Keep the ima policy rules around from the beginning even
if they appear invalid at the time of loading, as they
may become active after the lsm policy load. In other
words, now the lsm and the ima can be initialized in any
order and the handling logic is the same as with the lsm
rule reload event.

Patch also fixes the rule re-use during the lsm policy
reload and makes some prints a bit more human readable.

Cc: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
Reported-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
Signed-off-by: Janne Karhunen <janne.karhunen@xxxxxxxxx>
Signed-off-by: Konsta Karsisto <konsta.karsisto@xxxxxxxxx>
---
 security/integrity/ima/ima_policy.c | 44 ++++++++++++++---------------
 1 file changed, 21 insertions(+), 23 deletions(-)

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index a4dde9d575b2..4022c7736fc3 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -265,7 +265,7 @@ static void ima_lsm_free_rule(struct ima_rule_entry *entry)
 static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
 {
 	struct ima_rule_entry *nentry;
-	int i, result;
+	int i;
 
 	nentry = kmalloc(sizeof(*nentry), GFP_KERNEL);
 	if (!nentry)
@@ -279,7 +279,7 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
 	memset(nentry->lsm, 0, FIELD_SIZEOF(struct ima_rule_entry, lsm));
 
 	for (i = 0; i < MAX_LSM_RULES; i++) {
-		if (!entry->lsm[i].rule)
+		if (!entry->lsm[i].args_p)
 			continue;
 
 		nentry->lsm[i].type = entry->lsm[i].type;
@@ -288,13 +288,13 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
 		if (!nentry->lsm[i].args_p)
 			goto out_err;
 
-		result = security_filter_rule_init(nentry->lsm[i].type,
-						   Audit_equal,
-						   nentry->lsm[i].args_p,
-						   &nentry->lsm[i].rule);
-		if (result == -EINVAL)
-			pr_warn("ima: rule for LSM \'%d\' is undefined\n",
-				entry->lsm[i].type);
+		security_filter_rule_init(nentry->lsm[i].type,
+					  Audit_equal,
+					  nentry->lsm[i].args_p,
+					  &nentry->lsm[i].rule);
+		if (!nentry->lsm[i].rule)
+			pr_warn("rule for LSM \'%s\' is undefined\n",
+				(char *)entry->lsm[i].args_p);
 	}
 	return nentry;
 
@@ -331,7 +331,9 @@ static void ima_lsm_update_rules(void)
 	list_for_each_entry_safe(entry, e, &ima_policy_rules, list) {
 		needs_update = 0;
 		for (i = 0; i < MAX_LSM_RULES; i++) {
-			if (entry->lsm[i].rule) {
+			if (entry->lsm[i].args_p) {
+				pr_info("rule for LSM \'%s\' needs update\n",
+					(char *)entry->lsm[i].args_p);
 				needs_update = 1;
 				break;
 			}
@@ -341,8 +343,7 @@ static void ima_lsm_update_rules(void)
 
 		result = ima_lsm_update_rule(entry);
 		if (result) {
-			pr_err("ima: lsm rule update error %d\n",
-				result);
+			pr_err("lsm rule update error %d\n", result);
 			return;
 		}
 	}
@@ -865,8 +866,6 @@ static const match_table_t policy_tokens = {
 static int ima_lsm_rule_init(struct ima_rule_entry *entry,
 			     substring_t *args, int lsm_rule, int audit_type)
 {
-	int result;
-
 	if (entry->lsm[lsm_rule].rule)
 		return -EINVAL;
 
@@ -875,16 +874,15 @@ static int ima_lsm_rule_init(struct ima_rule_entry *entry,
 		return -ENOMEM;
 
 	entry->lsm[lsm_rule].type = audit_type;
-	result = security_filter_rule_init(entry->lsm[lsm_rule].type,
-					   Audit_equal,
-					   entry->lsm[lsm_rule].args_p,
-					   &entry->lsm[lsm_rule].rule);
-	if (!entry->lsm[lsm_rule].rule) {
-		kfree(entry->lsm[lsm_rule].args_p);
-		return -EINVAL;
-	}
+	security_filter_rule_init(entry->lsm[lsm_rule].type,
+				  Audit_equal,
+				  entry->lsm[lsm_rule].args_p,
+				  &entry->lsm[lsm_rule].rule);
+	if (!entry->lsm[lsm_rule].rule)
+		pr_warn("rule for LSM \'%s\' is undefined\n",
+			(char *)entry->lsm[lsm_rule].args_p);
 
-	return result;
+	return 0;
 }
 
 static void ima_log_string_op(struct audit_buffer *ab, char *key, char *value,
-- 
2.17.1