Smack: smackfs cipso seq read repair

Commit 272cd7a8 introduced
a change to the way rule lists are handled and reported in
the smackfs filesystem. One of the issues addressed had to
do with the termination of read requests on /smack/load.
This change introduced a error in /smack/cipso, which shares
some of the same list processing code.

This patch updates all the file access list handling in
smackfs to use the code introduced for /smack/load.
Signed-off-by: NCasey Schaufler <casey@schaufler-ca.com>

security/smack/smackfs.c

@@ -102,9 +102,6 @@ static int smk_cipso_doi_value = SMACK_CIPSO_DOI_DEFAULT;
 
 const char *smack_cipso_option = SMACK_CIPSO_OPTION;
 
-
-#define	SEQ_READ_FINISHED	((loff_t)-1)
-
 /*
  * Values for parsing cipso rules
  * SMK_DIGITLEN: Length of a digit field in a rule.
@@ -357,10 +354,12 @@ static ssize_t smk_write_load_list(struct file *file, const char __user *buf,
 
 	rc = count;
 	/*
+	 * If this is "load" as opposed to "load-self" and a new rule
+	 * it needs to get added for reporting.
 	 * smk_set_access returns true if there was already a rule
 	 * for the subject/object pair, and false if it was new.
 	 */
-	if (!smk_set_access(rule, rule_list, rule_lock)) {
+	if (load && !smk_set_access(rule, rule_list, rule_lock)) {
 		smlp = kzalloc(sizeof(*smlp), GFP_KERNEL);
 		if (smlp != NULL) {
 			smlp->smk_rule = rule;
@@ -377,12 +376,12 @@ static ssize_t smk_write_load_list(struct file *file, const char __user *buf,
 	return rc;
 }
 
-
 /*
- * Seq_file read operations for /smack/load
+ * Core logic for smackfs seq list operations.
  */
 
-static void *load_seq_start(struct seq_file *s, loff_t *pos)
+static void *smk_seq_start(struct seq_file *s, loff_t *pos,
+				struct list_head *head)
 {
 	struct list_head *list;
 
@@ -390,7 +389,7 @@ static void *load_seq_start(struct seq_file *s, loff_t *pos)
 	 * This is 0 the first time through.
 	 */
 	if (s->index == 0)
-		s->private = &smack_rule_list;
+		s->private = head;
 
 	if (s->private == NULL)
 		return NULL;
@@ -404,11 +403,12 @@ static void *load_seq_start(struct seq_file *s, loff_t *pos)
 	return list;
 }
 
-static void *load_seq_next(struct seq_file *s, void *v, loff_t *pos)
+static void *smk_seq_next(struct seq_file *s, void *v, loff_t *pos,
+				struct list_head *head)
 {
 	struct list_head *list = v;
 
-	if (list_is_last(list, &smack_rule_list)) {
+	if (list_is_last(list, head)) {
 		s->private = NULL;
 		return NULL;
 	}
@@ -416,6 +416,25 @@ static void *load_seq_next(struct seq_file *s, void *v, loff_t *pos)
 	return list->next;
 }
 
+static void smk_seq_stop(struct seq_file *s, void *v)
+{
+	/* No-op */
+}
+
+/*
+ * Seq_file read operations for /smack/load
+ */
+
+static void *load_seq_start(struct seq_file *s, loff_t *pos)
+{
+	return smk_seq_start(s, pos, &smack_rule_list);
+}
+
+static void *load_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	return smk_seq_next(s, v, pos, &smack_rule_list);
+}
+
 static int load_seq_show(struct seq_file *s, void *v)
 {
 	struct list_head *list = v;
@@ -446,16 +465,11 @@ static int load_seq_show(struct seq_file *s, void *v)
 	return 0;
 }
 
-static void load_seq_stop(struct seq_file *s, void *v)
-{
-	/* No-op */
-}
-
 static const struct seq_operations load_seq_ops = {
 	.start = load_seq_start,
 	.next  = load_seq_next,
 	.show  = load_seq_show,
-	.stop  = load_seq_stop,
+	.stop  = smk_seq_stop,
 };
 
 /**
@@ -574,28 +588,12 @@ static void smk_unlbl_ambient(char *oldambient)
 
 static void *cipso_seq_start(struct seq_file *s, loff_t *pos)
 {
-	if (*pos == SEQ_READ_FINISHED)
-		return NULL;
-	if (list_empty(&smack_known_list))
-		return NULL;
-
-	return smack_known_list.next;
+	return smk_seq_start(s, pos, &smack_known_list);
 }
 
 static void *cipso_seq_next(struct seq_file *s, void *v, loff_t *pos)
 {
-	struct list_head  *list = v;
-
-	/*
-	 * labels with no associated cipso value wont be printed
-	 * in cipso_seq_show
-	 */
-	if (list_is_last(list, &smack_known_list)) {
-		*pos = SEQ_READ_FINISHED;
-		return NULL;
-	}
-
-	return list->next;
+	return smk_seq_next(s, v, pos, &smack_known_list);
 }
 
 /*
@@ -634,16 +632,11 @@ static int cipso_seq_show(struct seq_file *s, void *v)
 	return 0;
 }
 
-static void cipso_seq_stop(struct seq_file *s, void *v)
-{
-	/* No-op */
-}
-
 static const struct seq_operations cipso_seq_ops = {
 	.start = cipso_seq_start,
-	.stop  = cipso_seq_stop,
 	.next  = cipso_seq_next,
 	.show  = cipso_seq_show,
+	.stop  = smk_seq_stop,
 };
 
 /**
@@ -788,23 +781,12 @@ static const struct file_operations smk_cipso_ops = {
 
 static void *netlbladdr_seq_start(struct seq_file *s, loff_t *pos)
 {
-	if (*pos == SEQ_READ_FINISHED)
-		return NULL;
-	if (list_empty(&smk_netlbladdr_list))
-		return NULL;
-	return smk_netlbladdr_list.next;
+	return smk_seq_start(s, pos, &smk_netlbladdr_list);
 }
 
 static void *netlbladdr_seq_next(struct seq_file *s, void *v, loff_t *pos)
 {
-	struct list_head *list = v;
-
-	if (list_is_last(list, &smk_netlbladdr_list)) {
-		*pos = SEQ_READ_FINISHED;
-		return NULL;
-	}
-
-	return list->next;
+	return smk_seq_next(s, v, pos, &smk_netlbladdr_list);
 }
 #define BEBITS	(sizeof(__be32) * 8)
 
@@ -828,16 +810,11 @@ static int netlbladdr_seq_show(struct seq_file *s, void *v)
 	return 0;
 }
 
-static void netlbladdr_seq_stop(struct seq_file *s, void *v)
-{
-	/* No-op */
-}
-
 static const struct seq_operations netlbladdr_seq_ops = {
 	.start = netlbladdr_seq_start,
-	.stop  = netlbladdr_seq_stop,
 	.next  = netlbladdr_seq_next,
 	.show  = netlbladdr_seq_show,
+	.stop  = smk_seq_stop,
 };
 
 /**
@@ -1405,23 +1382,14 @@ static void *load_self_seq_start(struct seq_file *s, loff_t *pos)
 {
 	struct task_smack *tsp = current_security();
 
-	if (*pos == SEQ_READ_FINISHED)
-		return NULL;
-	if (list_empty(&tsp->smk_rules))
-		return NULL;
-	return tsp->smk_rules.next;
+	return smk_seq_start(s, pos, &tsp->smk_rules);
 }
 
 static void *load_self_seq_next(struct seq_file *s, void *v, loff_t *pos)
 {
 	struct task_smack *tsp = current_security();
-	struct list_head *list = v;
 
-	if (list_is_last(list, &tsp->smk_rules)) {
-		*pos = SEQ_READ_FINISHED;
-		return NULL;
-	}
-	return list->next;
+	return smk_seq_next(s, v, pos, &tsp->smk_rules);
 }
 
 static int load_self_seq_show(struct seq_file *s, void *v)
@@ -1453,16 +1421,11 @@ static int load_self_seq_show(struct seq_file *s, void *v)
 	return 0;
 }
 
-static void load_self_seq_stop(struct seq_file *s, void *v)
-{
-	/* No-op */
-}
-
 static const struct seq_operations load_self_seq_ops = {
 	.start = load_self_seq_start,
 	.next  = load_self_seq_next,
 	.show  = load_self_seq_show,
-	.stop  = load_self_seq_stop,
+	.stop  = smk_seq_stop,
 };