ima: properly free ima_template_entry structures

The new templates management mechanism records information associated
to an event into an array of 'ima_field_data' structures and makes it
available through the 'template_data' field of the 'ima_template_entry'
structure (the element of the measurements list created by IMA).

Since 'ima_field_data' contains dynamically allocated data (which length
varies depending on the data associated to a selected template field),
it is not enough to just free the memory reserved for a
'ima_template_entry' structure if something goes wrong.

This patch creates the new function ima_free_template_entry() which
walks the array of 'ima_field_data' structures, frees the memory
referenced by the 'data' pointer and finally the space reserved for
the 'ima_template_entry' structure. Further, it replaces existing kfree()
that have a pointer to an 'ima_template_entry' structure as argument
with calls to the new function.

Fixes: a71dc65d: ima: switch to new template management mechanism
Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>

security/integrity/ima/ima.h

@@ -148,6 +148,7 @@ int ima_alloc_init_template(struct integrity_iint_cache *iint,
 			    int xattr_len, struct ima_template_entry **entry);
 int ima_store_template(struct ima_template_entry *entry, int violation,
 		       struct inode *inode, const unsigned char *filename);
+void ima_free_template_entry(struct ima_template_entry *entry);
 const char *ima_d_path(struct path *path, char **pathbuf);
 
 /* rbtree tree calls to lookup, insert, delete

security/integrity/ima/ima_api.c

@@ -21,6 +21,19 @@
 #include <crypto/hash_info.h>
 #include "ima.h"
 
+/*
+ * ima_free_template_entry - free an existing template entry
+ */
+void ima_free_template_entry(struct ima_template_entry *entry)
+{
+	int i;
+
+	for (i = 0; i < entry->template_desc->num_fields; i++)
+		kfree(entry->template_data[i].data);
+
+	kfree(entry);
+}
+
 /*
  * ima_alloc_init_template - create and initialize a new template entry
  */
@@ -37,6 +50,7 @@ int ima_alloc_init_template(struct integrity_iint_cache *iint,
 	if (!*entry)
 		return -ENOMEM;
 
+	(*entry)->template_desc = template_desc;
 	for (i = 0; i < template_desc->num_fields; i++) {
 		struct ima_template_field *field = template_desc->fields[i];
 		u32 len;
@@ -51,10 +65,9 @@ int ima_alloc_init_template(struct integrity_iint_cache *iint,
 		(*entry)->template_data_len += sizeof(len);
 		(*entry)->template_data_len += len;
 	}
-	(*entry)->template_desc = template_desc;
 	return 0;
 out:
-	kfree(*entry);
+	ima_free_template_entry(*entry);
 	*entry = NULL;
 	return result;
 }
@@ -134,7 +147,7 @@ void ima_add_violation(struct file *file, const unsigned char *filename,
 	}
 	result = ima_store_template(entry, violation, inode, filename);
 	if (result < 0)
-		kfree(entry);
+		ima_free_template_entry(entry);
 err_out:
 	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
 			    op, cause, result, 0);
@@ -269,7 +282,7 @@ void ima_store_measurement(struct integrity_iint_cache *iint,
 	if (!result || result == -EEXIST)
 		iint->flags |= IMA_MEASURED;
 	if (result < 0)
-		kfree(entry);
+		ima_free_template_entry(entry);
 }
 
 void ima_audit_measurement(struct integrity_iint_cache *iint,

security/integrity/ima/ima_init.c

@@ -75,7 +75,7 @@ static void __init ima_add_boot_aggregate(void)
 	result = ima_store_template(entry, violation, NULL,
 				    boot_aggregate_name);
 	if (result < 0)
-		kfree(entry);
+		ima_free_template_entry(entry);
 	return;
 err_out:
 	integrity_audit_msg(AUDIT_INTEGRITY_PCR, NULL, boot_aggregate_name, op,