[PATCH v3 7/9] ima: support restoring multiple template formats

[Mimi Zohar]

The configured IMA measurement list template format can be replaced at
runtime on the boot command line, including a custom template format.
This patch adds support for restoring a measuremement list containing
multiple builtin/custom template formats.

Changelog v3:
- initialize template format list in ima_template_desc_current(), as it
might be called during __setup before normal initialization. (kernel
test robot)
- remove __init annotation of ima_init_template_list()

Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
---
 security/integrity/ima/ima_template.c | 64 ++++++++++++++++++++++++++++++++---
 1 file changed, 59 insertions(+), 5 deletions(-)

diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c
index e1f9ce7..e689b572f 100644
--- a/security/integrity/ima/ima_template.c
+++ b/security/integrity/ima/ima_template.c
@@ -57,6 +57,8 @@ static int __init ima_template_setup(char *str)
 	if (ima_template)
 		return 1;
 
+	ima_init_template_list();
+
 	/*
 	 * Verify that a template with the supplied name exists.
 	 * If not, use CONFIG_IMA_DEFAULT_TEMPLATE.
@@ -153,9 +155,14 @@ static int template_desc_init_fields(const char *template_fmt,
 {
 	const char *template_fmt_ptr;
 	struct ima_template_field *found_fields[IMA_TEMPLATE_NUM_FIELDS_MAX];
-	int template_num_fields = template_fmt_size(template_fmt);
+	int template_num_fields;
 	int i, len;
 
+	if (num_fields && *num_fields > 0) /* already initialized? */
+		return 0;
+
+	template_num_fields = template_fmt_size(template_fmt);
+
 	if (template_num_fields > IMA_TEMPLATE_NUM_FIELDS_MAX) {
 		pr_err("format string '%s' contains too many fields\n",
 		       template_fmt);
@@ -193,10 +200,13 @@ static int template_desc_init_fields(const char *template_fmt,
 	return 0;
 }
 
-void __init ima_init_template_list(void)
+void ima_init_template_list(void)
 {
 	int i;
 
+	if (!list_empty(&defined_templates))
+		return;
+
 	spin_lock(&template_list);
 	for (i = 0; i < ARRAY_SIZE(builtin_templates); i++) {
 		list_add_tail_rcu(&builtin_templates[i].list,
@@ -208,9 +218,11 @@ void __init ima_init_template_list(void)
 
 struct ima_template_desc *ima_template_desc_current(void)
 {
-	if (!ima_template)
+	if (!ima_template) {
+		ima_init_template_list();
 		ima_template =
 		    lookup_template_desc(CONFIG_IMA_DEFAULT_TEMPLATE);
+	}
 	return ima_template;
 }
 
@@ -230,6 +242,35 @@ int __init ima_init_template(void)
 	return result;
 }
 
+static struct ima_template_desc *restore_template_fmt(char *template_name)
+{
+	struct ima_template_desc *template_desc = NULL;
+	int ret;
+
+	ret = template_desc_init_fields(template_name, NULL, NULL);
+	if (ret < 0) {
+		pr_err("attempting to initialize the template \"%s\" failed\n",
+			template_name);
+		goto out;
+	}
+
+	template_desc = kzalloc(sizeof(*template_desc), GFP_KERNEL);
+	if (!template_desc)
+		goto out;
+
+	template_desc->name = "";
+	template_desc->fmt = kstrdup(template_name, GFP_KERNEL);
+	if (!template_desc->fmt)
+		goto out;
+
+	spin_lock(&template_list);
+	list_add_tail_rcu(&template_desc->list, &defined_templates);
+	spin_unlock(&template_list);
+	synchronize_rcu();
+out:
+	return template_desc;
+}
+
 static int ima_restore_template_data(struct ima_template_desc *template_desc,
 				     void *template_data,
 				     int template_data_size,
@@ -360,10 +401,23 @@ int ima_restore_measurement_list(loff_t size, void *buf)
 		}
 		data_v1 = bufp += (u_int8_t)hdr_v1->template_name_len;
 
-		/* get template format */
 		template_desc = lookup_template_desc(template_name);
 		if (!template_desc) {
-			pr_err("template \"%s\" not found\n", template_name);
+			template_desc = restore_template_fmt(template_name);
+			if (!template_desc)
+				break;
+		}
+
+		/*
+		 * Only the running system's template format is initialized
+		 * on boot.  As needed, initialize the other template formats.
+		 */
+		ret = template_desc_init_fields(template_desc->fmt,
+						&(template_desc->fields),
+						&(template_desc->num_fields));
+		if (ret < 0) {
+			pr_err("attempting to restore the template fmt \"%s\" \
+				failed\n", template_desc->fmt);
 			ret = -EINVAL;
 			break;
 		}
-- 
2.1.0