[PATCH v4 20/23] appendedsig: Read default DB keys from the ELF Note

[Sudhakar Kuppusamy <sudhakar@linux.ibm.com>]

If Secure Boot is enabled with PKS and the use_static_keys flag is set,
then read the static keys as a DB default keys from the ELF note and
add stored in the db list.

Signed-off-by: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Avnish Chouhan <avnish@linux.ibm.com>
---
 grub-core/commands/appendedsig/appendedsig.c | 59 ++++++++++++++------
 1 file changed, 43 insertions(+), 16 deletions(-)

diff --git a/grub-core/commands/appendedsig/appendedsig.c b/grub-core/commands/appendedsig/appendedsig.c
index 1224fab9e..733cb32db 100644
--- a/grub-core/commands/appendedsig/appendedsig.c
+++ b/grub-core/commands/appendedsig/appendedsig.c
@@ -989,7 +989,7 @@ create_dbx_list (void)
  * parse it, and add it to the db list.
  */
 static grub_err_t
-build_static_db_list (const struct grub_module_header *header)
+build_static_db_list (const struct grub_module_header *header, const bool is_pks)
 {
   grub_err_t err;
   struct grub_file pseudo_file;
@@ -1008,6 +1008,12 @@ build_static_db_list (const struct grub_module_header *header)
   if (err != GRUB_ERR_NONE)
     return err;
 
+  if (is_pks == true)
+    {
+      if (is_dbx_cert_hash (cert_data, cert_data_size) == true)
+        return GRUB_ERR_ACCESS_DENIED;
+    }
+
   err = add_certificate (cert_data, cert_data_size, &db, true);
   grub_free (cert_data);
 
@@ -1060,6 +1066,25 @@ free_dbx_list (void)
   grub_memset (&dbx, 0, sizeof (dbx));
 }
 
+static grub_err_t
+load_static_keys (const struct grub_module_header *header, const bool is_pks)
+{
+  int rc = GRUB_ERR_NONE;
+
+  FOR_MODULES (header)
+    {
+      /* Not an ELF module, skip.  */
+      if (header->type != OBJ_TYPE_X509_PUBKEY)
+        continue;
+
+      rc = build_static_db_list (header, is_pks);
+      if (rc != GRUB_ERR_NONE)
+        return rc;
+    }
+
+  return rc;
+}
+
 GRUB_MOD_INIT (appendedsig)
 {
   int rc;
@@ -1078,26 +1103,28 @@ GRUB_MOD_INIT (appendedsig)
 
   if (!grub_pks_use_keystore && check_sigs == CHECK_SIGS_FORCED)
     {
-      FOR_MODULES (header)
+      rc = load_static_keys (header, false);
+      if (rc != GRUB_ERR_NONE)
         {
-          /* Not an ELF module, skip.  */
-          if (header->type != OBJ_TYPE_X509_PUBKEY)
-            continue;
-
-          rc = build_static_db_list (header);
-          if (rc != GRUB_ERR_NONE)
-            {
-              free_db_list ();
-              grub_error (rc, "static db list creation failed.");
-            }
-          else
-            grub_dprintf ("appendedsig", "the db list now has %" PRIuGRUB_SIZE " static keys.\n",
-                          db.cert_entries);
+          free_db_list ();
+          grub_error (rc, "static db list creation failed.");
         }
+      else
+        grub_dprintf ("appendedsig", "the db list now has %" PRIuGRUB_SIZE " static keys.\n",
+                      db.cert_entries);
     }
   else if (grub_pks_use_keystore && check_sigs == CHECK_SIGS_FORCED)
     {
-      rc = create_db_list ();
+
+      if (grub_pks_keystore.use_static_keys == true)
+        {
+          grub_printf ("Warning: db variable is not available at PKS and using a static keys "
+                       "as a default key in db list\n");
+          rc = load_static_keys (header, grub_pks_keystore.use_static_keys);
+        }
+      else
+        rc = create_db_list ();
+
       if (rc != GRUB_ERR_NONE)
         {
           free_db_list ();
-- 
2.39.5 (Apple Git-154)


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