From 228734ab023191ff8df42e83c615d7ab610a3aea Mon Sep 17 00:00:00 2001
From: Vladimir 'phcoder' Serbinenko <phcoder@gmail.com>
Date: Sun, 15 Nov 2009 23:36:42 +0100
Subject: [PATCH] MAX_PASSLEN based authentication

---
 commands/password.c | 13 ++++++++---
 include/grub/auth.h |  7 +-----
 normal/auth.c       | 56 ++-------------------------------------------
 3 files changed, 13 insertions(+), 63 deletions(-)

diff --git a/commands/password.c b/commands/password.c
index 0e048797e..247e0bffd 100644
--- a/commands/password.c
+++ b/commands/password.c
@@ -26,18 +26,20 @@
 
 static grub_dl_t my_mod;
 
+#define MAX_PASSLEN 1024
+
 static grub_err_t
 check_password (const char *user,
 		void *password)
 {
-  char entered[1024];
+  char entered[MAX_PASSLEN];
 
   grub_memset (entered, 0, sizeof (entered));
 
   if (!GRUB_GET_PASSWORD (entered, sizeof (entered) - 1))
     return GRUB_ACCESS_DENIED;
 
-  if (grub_auth_strcmp (entered, password) != 0)
+  if (grub_crypto_memcmp (entered, password, MAX_PASSLEN) != 0)
     return GRUB_ACCESS_DENIED;
 
   grub_auth_authenticate (user);
@@ -51,13 +53,18 @@ grub_cmd_password (grub_command_t cmd __attribute__ ((unused)),
 {
   grub_err_t err;
   char *pass;
+  int copylen;
 
   if (argc != 2)
     return grub_error (GRUB_ERR_BAD_ARGUMENT, "Two arguments expected.");
 
-  pass = grub_strdup (args[1]);
+  pass = grub_zalloc (MAX_PASSLEN);
   if (!pass)
     return grub_errno;
+  copylen = grub_strlen (argv[1]);
+  if (copylen >= MAX_PASSLEN)
+    copylen = MAX_PASSLEN - 1;
+  grub_memcpy (pass, argv[1], copylen);
 
   err = grub_auth_register_authentication (args[0], check_password, pass);
   if (err)
diff --git a/include/grub/auth.h b/include/grub/auth.h
index da930eeda..e72d984ae 100644
--- a/include/grub/auth.h
+++ b/include/grub/auth.h
@@ -15,7 +15,7 @@
  *  You should have received a copy of the GNU General Public License
  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  */
-#ifndef GRUB_AURH_HEADER
+#ifndef GRUB_AUTH_HEADER
 #define GRUB_AUTH_HEADER	1
 
 #include <grub/err.h>
@@ -26,11 +26,6 @@
 							 string, len,	\
 							 '*', 0, 0)
 
-/* Like strcmp but untimeable. Accepts NULL as second argument.  */
-int grub_auth_strcmp (const char *user_input, const char *template);
-/* Like strcmp but untimeable and ignores commas in needle.  */
-int grub_auth_strword (const char *haystack, const char *needle);
-
 typedef grub_err_t (*grub_auth_callback_t) (const char*, void *);
 
 grub_err_t grub_auth_register_authentication (const char *user,
diff --git a/normal/auth.c b/normal/auth.c
index c71262584..7d5a07d26 100644
--- a/normal/auth.c
+++ b/normal/auth.c
@@ -35,58 +35,6 @@ struct grub_auth_user
 
 struct grub_auth_user *users = NULL;
 
-int
-grub_auth_strcmp (const char *s1, const char *s2)
-{
-  int ret;
-  grub_uint64_t end;
-
-  end = grub_get_time_ms () + 100;
-  ret = grub_strcmp (s1, s2);
-
-  /* This prevents an attacker from deriving information about the
-     password from the time it took to execute this function.  */
-  while (grub_get_time_ms () < end);
-
-  return ret;
-}
-
-static int
-grub_iswordseparator (int c)
-{
-  return (grub_isspace (c) || c == ',' || c == ';' || c == '|' || c == '&');
-}
-
-int
-grub_auth_strword (const char *haystack, const char *needle)
-{
-  const char *n_pos = needle;
-  int found = 0;
-
-  while (grub_iswordseparator (*haystack))
-    haystack++;
-
-  while (*haystack)
-    {
-      int ok = 1;
-      /* Crawl both the needle and the haystack word we're on.  */
-      while(*haystack && !grub_iswordseparator (*haystack))
-        {
-	  if (*haystack == *n_pos && ok)
-	    n_pos++;
-	  else
-	    ok = 0;
-
-          haystack++;
-        }
-
-      if (ok)
-	found = 1;
-    }
-
-  return found;
-}
-
 grub_err_t
 grub_auth_register_authentication (const char *user,
 				   grub_auth_callback_t callback,
@@ -193,8 +141,8 @@ is_authenticated (const char *userlist)
       return 0;
     name = ((struct grub_auth_user *) item)->name;
 
-    return (userlist && grub_auth_strword (userlist, name))
-      || grub_auth_strword (superusers, name);
+    return (userlist && grub_strword (userlist, name))
+      || grub_strword (superusers, name);
   }
 
   superusers = grub_env_get ("superusers");