ima: added support for new kernel cmdline parameter ima_template_fmt

This patch allows users to provide a custom template format through the
new kernel command line parameter 'ima_template_fmt'. If the supplied
format is not valid, IMA uses the default template descriptor.

Changelog:
 - v3:
   - added check for 'fields' and 'num_fields' in
     template_desc_init_fields() (suggested by Mimi Zohar)

 - v2:
   - using template_desc_init_fields() to validate a format string
     (Roberto Sassu)
   - updated documentation by stating that only the chosen template
     descriptor is initialized (Roberto Sassu)

 - v1:
   - simplified code of ima_template_fmt_setup()
     (Roberto Sassu, suggested by Mimi Zohar)

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

1 files changed, 4 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 802a3fd9e485..06b2cd5739dd 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1318,6 +1318,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			Formats: { "ima" | "ima-ng" }
 			Default: "ima-ng"
 
+	ima_template_fmt=
+	                [IMA] Define a custom template format.
+			Format: { "field1|...|fieldN" }
+
 	ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage
 			Format: <min_file_size>
 			Set the minimal file size for using asynchronous hash.