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>

1 files changed, 17 insertions, 5 deletions

diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c
index e854862c9337..1310afc587f3 100644
--- 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;
 }