Thread (30 messages) 30 messages, 7 authors, 2016-08-11

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

From: Mimi Zohar <hidden>
Date: 2016-08-04 15:34:27
Also in: linuxppc-dev, lkml
Subsystem: extended verification module (evm), integrity measurement architecture (ima), security subsystem, the rest · Maintainers: Mimi Zohar, Roberto Sassu, Dmitry Kasatkin, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds

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.

Signed-off-by: Mimi Zohar <redacted>
---
 security/integrity/ima/ima_template.c | 58 +++++++++++++++++++++++++++++++++--
 1 file changed, 55 insertions(+), 3 deletions(-)
diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c
index b7bcb62..3923718 100644
--- a/security/integrity/ima/ima_template.c
+++ b/security/integrity/ima/ima_template.c
@@ -56,6 +56,8 @@ 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.
@@ -150,9 +152,14 @@ 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);
@@ -202,6 +209,9 @@ void __init 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,
@@ -227,6 +237,35 @@ 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,
@@ -359,10 +398,23 @@ 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


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