linux-kernel - [PATCH 6/7] ima: store the builtin/custom template definitions in a list

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Date:	Thu,  4 Aug 2016 08:24:34 -0400
From:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:	linux-security-module@...r.kernel.org
Cc:	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	linux-ima-devel@...ts.sourceforge.net,
	Dave Young <dyoung@...hat.com>, kexec@...ts.infradead.org,
	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>
Subject: [PATCH 6/7] ima: store the builtin/custom template definitions in a list

The builtin and single custom templates are currently stored in an
array.  In preparation for being able to restore a measurement list
containing multiple builtin/custom templates, this patch stores the
builtin and custom templates as a linked list.  This will permit
defining more than one custom template per boot.

Signed-off-by: Mimi Zohar <zohar@...ux.vnet.ibm.com>
---
 security/integrity/ima/ima.h          |  2 ++
 security/integrity/ima/ima_main.c     |  1 +
 security/integrity/ima/ima_template.c | 37 +++++++++++++++++++++++++++--------
 3 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index f972296..9d7fdd5 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -81,6 +81,7 @@ struct ima_template_field {
 
 /* IMA template descriptor definition */
 struct ima_template_desc {
+	struct list_head list;
 	char *name;
 	char *fmt;
 	int num_fields;
@@ -135,6 +136,7 @@ int ima_restore_measurement_list(loff_t bufsize, void *buf);
 int ima_measurements_show(struct seq_file *m, void *v);
 unsigned long ima_get_binary_runtime_size(void);
 int ima_init_template(void);
+void ima_init_template_list(void);
 
 /*
  * used to protect h_table and sha_table
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 596ef61..592f318 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -418,6 +418,7 @@ static int __init init_ima(void)
 {
 	int error;
 
+	ima_init_template_list();
 	hash_setup(CONFIG_IMA_DEFAULT_HASH);
 	error = ima_init();
 	if (!error) {
diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c
index c6510f0..b7bcb62 100644
--- a/security/integrity/ima/ima_template.c
+++ b/security/integrity/ima/ima_template.c
@@ -15,16 +15,20 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/rculist.h>
 #include "ima.h"
 #include "ima_template_lib.h"
 
-static struct ima_template_desc defined_templates[] = {
+static struct ima_template_desc builtin_templates[] = {
 	{.name = IMA_TEMPLATE_IMA_NAME, .fmt = IMA_TEMPLATE_IMA_FMT},
 	{.name = "ima-ng", .fmt = "d-ng|n-ng"},
 	{.name = "ima-sig", .fmt = "d-ng|n-ng|sig"},
 	{.name = "", .fmt = ""},	/* placeholder for a custom format */
 };
 
+static LIST_HEAD(defined_templates);
+spinlock_t template_list;
+
 static struct ima_template_field supported_fields[] = {
 	{.field_id = "d", .field_init = ima_eventdigest_init,
 	 .field_show = ima_show_template_digest},
@@ -80,7 +84,7 @@ __setup("ima_template=", ima_template_setup);
 
 static int __init ima_template_fmt_setup(char *str)
 {
-	int num_templates = ARRAY_SIZE(defined_templates);
+	int num_templates = ARRAY_SIZE(builtin_templates);
 
 	if (ima_template)
 		return 1;
@@ -91,20 +95,24 @@ static int __init ima_template_fmt_setup(char *str)
 		return 1;
 	}
 
-	defined_templates[num_templates - 1].fmt = str;
-	ima_template = defined_templates + num_templates - 1;
+	builtin_templates[num_templates - 1].fmt = str;
+	ima_template = builtin_templates + num_templates - 1;
+
 	return 1;
 }
 __setup("ima_template_fmt=", ima_template_fmt_setup);
 
 static struct ima_template_desc *lookup_template_desc(const char *name)
 {
-	int i;
+	struct ima_template_desc *template_desc;
 
-	for (i = 0; i < ARRAY_SIZE(defined_templates); i++) {
-		if (strcmp(defined_templates[i].name, name) == 0)
-			return defined_templates + i;
+	rcu_read_lock();
+	list_for_each_entry_rcu(template_desc, &defined_templates, list) {
+		if ((strcmp(template_desc->name, name) == 0) ||
+		    (strcmp(template_desc->fmt, name) == 0))
+			return template_desc;
 	}
+	rcu_read_unlock();
 
 	return NULL;
 }
@@ -190,6 +198,19 @@ struct ima_template_desc *ima_template_desc_current(void)
 	return ima_template;
 }
 
+void __init ima_init_template_list(void)
+{
+	int i;
+
+	spin_lock(&template_list);
+	for (i = 0; i < ARRAY_SIZE(builtin_templates); i++) {
+		list_add_tail_rcu(&builtin_templates[i].list,
+				  &defined_templates);
+	}
+	spin_unlock(&template_list);
+	synchronize_rcu();
+}
+
 int __init ima_init_template(void)
 {
 	struct ima_template_desc *template = ima_template_desc_current();
-- 
2.1.0