ima: extend the measurement list to include the file signature

This patch defines a new template called 'ima-sig', which includes
the file signature in the template data, in addition to the file's
digest and pathname.

A template is composed of a set of fields.  Associated with each
field is an initialization and display function.  This patch defines
a new template field called 'sig', the initialization function
ima_eventsig_init(), and the display function ima_show_template_sig().

This patch modifies the .field_init() function definition to include
the 'security.ima' extended attribute and length.

Changelog:
- remove unused code (Dmitry Kasatkin)
- avoid calling ima_write_template_field_data() unnecesarily (Roberto Sassu)
- rename DATA_FMT_SIG to DATA_FMT_HEX
- cleanup ima_eventsig_init() based on Roberto's comments

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

1 files changed, 36 insertions, 2 deletions

diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
index 7d841448f246..6d66ad6ed265 100644
--- a/security/integrity/ima/ima_template_lib.c
+++ b/security/integrity/ima/ima_template_lib.c
@@ -28,7 +28,8 @@ enum data_formats {
         DATA_FMT_DIGEST = 0,
         DATA_FMT_DIGEST_WITH_ALGO,
         DATA_FMT_EVENT_NAME,
-        DATA_FMT_STRING
+        DATA_FMT_STRING,
+        DATA_FMT_HEX
 };
 
 static int ima_write_template_field_data(const void *data, const u32 datalen,
@@ -90,6 +91,9 @@ static void ima_show_template_data_ascii(struct seq_file *m,
                 buf_ptr += 2;
                 buflen -= buf_ptr - field_data->data;
         case DATA_FMT_DIGEST:
+        case DATA_FMT_HEX:
+                if (!buflen)
+                        break;
                 ima_print_digest(m, buf_ptr, buflen);
                 break;
         case DATA_FMT_STRING:
@@ -147,6 +151,12 @@ void ima_show_template_string(struct seq_file *m, enum ima_show_type show,
         ima_show_template_field_data(m, show, DATA_FMT_STRING, field_data);
 }
 
+void ima_show_template_sig(struct seq_file *m, enum ima_show_type show,
+                           struct ima_field_data *field_data)
+{
+        ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
+}
+
 static int ima_eventdigest_init_common(u8 *digest, u32 digestsize, u8 hash_algo,
                                        struct ima_field_data *field_data,
                                        bool size_limit)
@@ -190,6 +200,7 @@ static int ima_eventdigest_init_common(u8 *digest, u32 digestsize, u8 hash_algo,
  */
 int ima_eventdigest_init(struct integrity_iint_cache *iint, struct file *file,
                          const unsigned char *filename,
+                         struct evm_ima_xattr_data *xattr_value, int xattr_len,
                          struct ima_field_data *field_data)
 {
         struct {
@@ -237,7 +248,8 @@ out:
  */
 int ima_eventdigest_ng_init(struct integrity_iint_cache *iint,
                             struct file *file, const unsigned char *filename,
-                            struct ima_field_data *field_data)
+                            struct evm_ima_xattr_data *xattr_value,
+                            int xattr_len, struct ima_field_data *field_data)
 {
         u8 *cur_digest = NULL, hash_algo = HASH_ALGO__LAST;
         u32 cur_digestsize = 0;
@@ -295,6 +307,7 @@ out:
  */
 int ima_eventname_init(struct integrity_iint_cache *iint, struct file *file,
                        const unsigned char *filename,
+                       struct evm_ima_xattr_data *xattr_value, int xattr_len,
                        struct ima_field_data *field_data)
 {
         return ima_eventname_init_common(iint, file, filename,
@@ -306,8 +319,29 @@ int ima_eventname_init(struct integrity_iint_cache *iint, struct file *file,
  */
 int ima_eventname_ng_init(struct integrity_iint_cache *iint, struct file *file,
                           const unsigned char *filename,
+                          struct evm_ima_xattr_data *xattr_value, int xattr_len,
                           struct ima_field_data *field_data)
 {
         return ima_eventname_init_common(iint, file, filename,
                                          field_data, false);
 }
+
+/*
+ *  ima_eventsig_init - include the file signature as part of the template data
+ */
+int ima_eventsig_init(struct integrity_iint_cache *iint, struct file *file,
+                      const unsigned char *filename,
+                      struct evm_ima_xattr_data *xattr_value, int xattr_len,
+                      struct ima_field_data *field_data)
+{
+        enum data_formats fmt = DATA_FMT_HEX;
+        int rc = 0;
+
+        if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG))
+                goto out;
+
+        rc = ima_write_template_field_data(xattr_value, xattr_len, fmt,
+                                           field_data);
+out:
+        return rc;
+}