ima: define kernel parameter 'ima_template=' to change configured default

This patch allows users to specify from the kernel command line the
template descriptor, among those defined, that will be used to generate
and display measurement entries. If an user specifies a wrong template,
IMA reverts to the template descriptor set in the kernel configuration.

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 1a036cd972fb0c205109ed66b968c3d771f66418..2b78cb55ac34e66a0a5b2ab936be823c1641b940 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1190,6 +1190,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                        programs exec'd, files mmap'd for exec, and all files
                        opened for read by uid=0.
 
+       ima_template=   [IMA]
+                       Select one of defined IMA measurements template formats.
+                       Formats: { "ima" | "ima-ng" }
+                       Default: "ima-ng"
+
        init=           [KNL]
                        Format: <full_path>
                        Run specified binary instead of /sbin/init as init

diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c
index c28ff9bf8f327e6d19c7c25025a728bdc6d00716..000221419f6c95d0efcec7bdc69c1be4e2269186 100644 (file)
--- a/security/integrity/ima/ima_template.c
+++ b/security/integrity/ima/ima_template.c
@@ -12,6 +12,8 @@
  * File: ima_template.c
  *      Helpers to manage template descriptors.
  */
+#include <crypto/hash_info.h>
+
 #include "ima.h"
 #include "ima_template_lib.h"
 
@@ -32,6 +34,35 @@ static struct ima_template_field supported_fields[] = {
 };
 
 static struct ima_template_desc *ima_template;
+static struct ima_template_desc *lookup_template_desc(const char *name);
+
+static int __init ima_template_setup(char *str)
+{
+       struct ima_template_desc *template_desc;
+       int template_len = strlen(str);
+
+       /*
+        * Verify that a template with the supplied name exists.
+        * If not, use CONFIG_IMA_DEFAULT_TEMPLATE.
+        */
+       template_desc = lookup_template_desc(str);
+       if (!template_desc)
+               return 1;
+
+       /*
+        * Verify whether the current hash algorithm is supported
+        * by the 'ima' template.
+        */
+       if (template_len == 3 && strcmp(str, IMA_TEMPLATE_IMA_NAME) == 0 &&
+           ima_hash_algo != HASH_ALGO_SHA1 && ima_hash_algo != HASH_ALGO_MD5) {
+               pr_err("IMA: template does not support hash alg\n");
+               return 1;
+       }
+
+       ima_template = template_desc;
+       return 1;
+}
+__setup("ima_template=", ima_template_setup);
 
 static struct ima_template_desc *lookup_template_desc(const char *name)
 {