ima: added error messages to template-related functions

This patch adds some error messages to inform users about the following
events: template descriptor not found, invalid template descriptor,
template field not found and template initialization failed.

Changelog:
 - v2:
   - display an error message if the format string contains too many
     fields (Roberto Sassu)

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

diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c
index e854862..1310afc 100644 (file)
--- a/security/integrity/ima/ima_template.c
+++ b/security/integrity/ima/ima_template.c
@@ -52,8 +52,11 @@ static int __init ima_template_setup(char *str)
         * If not, use CONFIG_IMA_DEFAULT_TEMPLATE.
         */
        template_desc = lookup_template_desc(str);
-       if (!template_desc)
+       if (!template_desc) {
+               pr_err("template %s not found, using %s\n",
+                      str, CONFIG_IMA_DEFAULT_TEMPLATE);
                return 1;
+       }
 
        /*
         * Verify whether the current hash algorithm is supported
@@ -117,8 +120,11 @@ static int template_desc_init_fields(const char *template_fmt,
        int template_num_fields = template_fmt_size(template_fmt);
        int i, result = 0;
 
-       if (template_num_fields > IMA_TEMPLATE_NUM_FIELDS_MAX)
+       if (template_num_fields > IMA_TEMPLATE_NUM_FIELDS_MAX) {
+               pr_err("format string '%s' contains too many fields\n",
+                      template_fmt);
                return -EINVAL;
+       }
 
        /* copying is needed as strsep() modifies the original buffer */
        template_fmt_copy = kstrdup(template_fmt, GFP_KERNEL);
@@ -137,6 +143,7 @@ static int template_desc_init_fields(const char *template_fmt,
                struct ima_template_field *f = lookup_template_field(c);
 
                if (!f) {
+                       pr_err("field '%s' not found\n", c);
                        result = -ENOENT;
                        goto out;
                }
@@ -163,8 +170,13 @@ struct ima_template_desc *ima_template_desc_current(void)
 int __init ima_init_template(void)
 {
        struct ima_template_desc *template = ima_template_desc_current();
+       int result;
 
-       return template_desc_init_fields(template->fmt,
-                                        &(template->fields),
-                                        &(template->num_fields));
+       result = template_desc_init_fields(template->fmt,
+                                          &(template->fields),
+                                          &(template->num_fields));
+       if (result < 0)
+               pr_err("template %s init failed, result: %d\n", template->name);
+
+       return result;
 }