ima: handle multiple rules per write

Currently IMA will only accept one rule per write().  This patch allows IMA to
accept writes which contain multiple rules but only processes one rule per
write.  \n is used as the delimiter between rules.  IMA will return a short
write indicating that it only accepted up to the first \n.

This allows simple userspace utilities like cat to be used to load an IMA
policy instead of needing a special userspace utility that understood 'one
write per rule'

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 11 insertions, 7 deletions

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 4759d0f99335..49998f90e441 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -261,7 +261,7 @@ static int ima_parse_rule(char *rule, struct ima_measure_rule_entry *entry)
 	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);
 
 	entry->action = -1;
-	while ((p = strsep(&rule, " \n")) != NULL) {
+	while ((p = strsep(&rule, " ")) != NULL) {
 		substring_t args[MAX_OPT_ARGS];
 		int token;
 		unsigned long lnum;
@@ -269,7 +269,7 @@ static int ima_parse_rule(char *rule, struct ima_measure_rule_entry *entry)
 		if (result < 0)
 			break;
 		if (!*p)
-			continue;
+			break;
 		token = match_token(p, policy_tokens, args);
 		switch (token) {
 		case Opt_measure:
@@ -373,7 +373,7 @@ static int ima_parse_rule(char *rule, struct ima_measure_rule_entry *entry)
 	if (entry->action == UNKNOWN)
 		result = -EINVAL;
 
-	audit_log_format(ab, "res=%d", !result ? 0 : 1);
+	audit_log_format(ab, "res=%d", !!result);
 	audit_log_end(ab);
 	return result;
 }
@@ -383,13 +383,14 @@ static int ima_parse_rule(char *rule, struct ima_measure_rule_entry *entry)
  * @rule - ima measurement policy rule
  *
  * Uses a mutex to protect the policy list from multiple concurrent writers.
- * Returns 0 on success, an error code on failure.
+ * Returns the length of the rule parsed, an error code on failure
  */
-int ima_parse_add_rule(char *rule)
+ssize_t ima_parse_add_rule(char *rule)
 {
 	const char *op = "update_policy";
+	char *p;
 	struct ima_measure_rule_entry *entry;
-	int result = 0;
+	ssize_t result, len;
 	int audit_info = 0;
 
 	/* Prevent installed policy from changing */
@@ -409,8 +410,11 @@ int ima_parse_add_rule(char *rule)
 
 	INIT_LIST_HEAD(&entry->list);
 
-	result = ima_parse_rule(rule, entry);
+	p = strsep(&rule, "\n");
+	len = strlen(p) + 1;
+	result = ima_parse_rule(p, entry);
 	if (!result) {
+		result = len;
 		mutex_lock(&ima_measure_mutex);
 		list_add_tail(&entry->list, &measure_policy_rules);
 		mutex_unlock(&ima_measure_mutex);