From 389f8af28dcc1f7620fabf5032f680fba0bd28e3 Mon Sep 17 00:00:00 2001

From: Vladimir 'phcoder' Serbinenko <phcoder@gmail.com>

Date: Wed, 3 Apr 2013 17:32:33 +0200

Subject: [PATCH 249/482] 	* grub-core/commands/verify.c: Save verified

 file to avoid it being 	tampered with after verification was done.

---

 ChangeLog                   |  5 +++

 grub-core/commands/verify.c | 98 +++++++++++++++++++++++++++++++++++++--------

 include/grub/misc.h         |  2 +

 3 files changed, 88 insertions(+), 17 deletions(-)

diff --git a/ChangeLog b/ChangeLog

index b0c57bb..6dc95ba 100644

--- a/ChangeLog

+++ b/ChangeLog

@@ -1,5 +1,10 @@

 2013-04-03  Vladimir Serbinenko  <phcoder@gmail.com>

+	* grub-core/commands/verify.c: Save verified file to avoid it being

+	tampered with after verification was done.

+

+2013-04-03  Vladimir Serbinenko  <phcoder@gmail.com>

+

 	* grub-core/term/i386/pc/console.c (grub_console_getwh): Decrease

 	reported width by one to compensate for curesor algorithm problem.

diff --git a/grub-core/commands/verify.c b/grub-core/commands/verify.c

index b4d5e7b..bd47611 100644

--- a/grub-core/commands/verify.c

+++ b/grub-core/commands/verify.c

@@ -1,6 +1,6 @@

 /*

  *  GRUB  --  GRand Unified Bootloader

- *  Copyright (C) 2011  Free Software Foundation, Inc.

+ *  Copyright (C) 2013  Free Software Foundation, Inc.

  *

  *  GRUB is free software: you can redistribute it and/or modify

  *  it under the terms of the GNU General Public License as published by

@@ -338,9 +338,10 @@ grub_crypto_pk_locate_subkey_in_trustdb (grub_uint64_t keyid)

   return 0;

 }

-grub_err_t

-grub_verify_signature (grub_file_t f, grub_file_t sig,

-		       struct grub_public_key *pkey)

+static grub_err_t

+grub_verify_signature_real (char *buf, grub_size_t size,

+			    grub_file_t f, grub_file_t sig,

+			    struct grub_public_key *pkey)

 {

   grub_size_t len;

   grub_uint8_t v;

@@ -404,16 +405,19 @@ grub_verify_signature (grub_file_t f, grub_file_t sig,

     grub_memset (context, 0, sizeof (context));

     hash->init (context);

-    while (1)

-      {

-	grub_uint8_t readbuf[4096];

-	r = grub_file_read (f, readbuf, sizeof (readbuf));

-	if (r < 0)

-	  return grub_errno;

-	if (r == 0)

-	  break;

-	hash->write (context, readbuf, r);

-      }

+    if (buf)

+      hash->write (context, buf, size);

+    else 

+      while (1)

+	{

+	  grub_uint8_t readbuf[4096];

+	  r = grub_file_read (f, readbuf, sizeof (readbuf));

+	  if (r < 0)

+	    return grub_errno;

+	  if (r == 0)

+	    break;

+	  hash->write (context, readbuf, r);

+	}

     hash->write (context, &v, sizeof (v));

     hash->write (context, &v4, sizeof (v4));

@@ -532,6 +536,13 @@ grub_verify_signature (grub_file_t f, grub_file_t sig,

   return GRUB_ERR_NONE;

 }

+grub_err_t

+grub_verify_signature (grub_file_t f, grub_file_t sig,

+		       struct grub_public_key *pkey)

+{

+  return grub_verify_signature_real (0, 0, f, sig, pkey);

+}

+

 static grub_err_t

 grub_cmd_trust (grub_command_t cmd  __attribute__ ((unused)),

 			   int argc, char **args)

@@ -665,6 +676,28 @@ grub_cmd_verify_signature (grub_command_t cmd  __attribute__ ((unused)),

 static int sec = 0;

+static grub_ssize_t

+verified_read (struct grub_file *file, char *buf, grub_size_t len)

+{

+  grub_memcpy (buf, (char *) file->data + file->offset, len);

+  return len;

+}

+

+static grub_err_t

+verified_close (struct grub_file *file)

+{

+  grub_free (file->data);

+  file->data = 0;

+  return GRUB_ERR_NONE;

+}

+

+struct grub_fs verified_fs =

+{

+  .name = "verified_read",

+  .read = verified_read,

+  .close = verified_close

+};

+

 static grub_file_t

 grub_pubkey_open (grub_file_t io, const char *filename)

 {

@@ -672,9 +705,12 @@ grub_pubkey_open (grub_file_t io, const char *filename)

   char *fsuf, *ptr;

   grub_err_t err;

   grub_file_filter_t curfilt[GRUB_FILE_FILTER_MAX];

+  grub_file_t ret;

   if (!sec)

     return io;

+  if (io->device->disk && io->device->disk->id == GRUB_DISK_DEVICE_MEMDISK_ID)

+    return io;

   fsuf = grub_malloc (grub_strlen (filename) + sizeof (".sig"));

   if (!fsuf)

     return NULL;

@@ -691,12 +727,40 @@ grub_pubkey_open (grub_file_t io, const char *filename)

   if (!sig)

     return NULL;

-  err = grub_verify_signature (io, sig, NULL);

+  ret = grub_malloc (sizeof (*ret));

+  if (!ret)

+    return NULL;

+  *ret = *io;

+

+  ret->fs = &verified_fs;

+  ret->not_easily_seekable = 0;

+  if (ret->size >> (sizeof (grub_size_t) * GRUB_CHAR_BIT - 1))

+    {

+      grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,

+		  "big file signature isn't implemented yet");

+      return NULL;

+    }

+  ret->data = grub_malloc (ret->size);

+  if (!ret->data)

+    {

+      grub_free (ret);

+      return NULL;

+    }

+  if (grub_file_read (io, ret->data, ret->size) != (grub_ssize_t) ret->size)

+    {

+      if (!grub_errno)

+	grub_error (GRUB_ERR_FILE_READ_ERROR, N_("premature end of file %s"),

+		    filename);

+      return NULL;

+    }

+

+  err = grub_verify_signature_real (ret->data, ret->size, 0, sig, NULL);

   grub_file_close (sig);

   if (err)

     return NULL;

-  grub_file_seek (io, 0);

-  return io;

+  io->device = 0;

+  grub_file_close (io);

+  return ret;

 }

 static char *

diff --git a/include/grub/misc.h b/include/grub/misc.h

index c953a00..0ea5114 100644

--- a/include/grub/misc.h

+++ b/include/grub/misc.h

@@ -481,4 +481,6 @@ void EXPORT_FUNC(grub_real_boot_time) (const char *file,

 #define grub_max(a, b) (((a) > (b)) ? (a) : (b))

 #define grub_min(a, b) (((a) < (b)) ? (a) : (b))

+#define GRUB_CHAR_BIT 8

+

 #endif /* ! GRUB_MISC_HEADER */

-- 

1.8.2.1