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Description: Detect other software using embedding area
When embedding the core image in a post-MBR gap, check for and avoid
sectors matching any of the signatures in embed_signatures.
Author: Colin Watson <cjwatson@ubuntu.com>
Origin: upstream, http://bzr.sv.gnu.org/r/grub/branches/embed-sectors/
Forwarded: http://lists.gnu.org/archive/html/grub-devel/2010-08/msg00137.html
Last-Update: 2011-04-21
Index: b/ChangeLog.embed-sectors
===================================================================
--- /dev/null
+++ b/ChangeLog.embed-sectors
@@ -0,0 +1,12 @@
+2011-03-14 Colin Watson <cjwatson@ubuntu.com>
+
+ * include/grub/partition.h (grub_partition_map): Change prototype of
+ embed to take a maximum value for nsectors.
+ * grub-core/partmap/msdos.c (embed_signatures): New array.
+ (pc_partition_map_embed): Check for and avoid sectors matching any
+ of the signatures in embed_signatures, up to max_nsectors.
+ * grub-core/partmap/gpt.c (gpt_partition_map_embed): Restrict
+ returned sector map to max_nsectors.
+ * util/grub-setup.c (setup): Allow for the embedding area being
+ split into multiple blocklists. Tell dest_partmap->embed the
+ maximum number of sectors we care about.
Index: b/grub-core/partmap/gpt.c
===================================================================
--- a/grub-core/partmap/gpt.c
+++ b/grub-core/partmap/gpt.c
@@ -127,6 +127,7 @@
#ifdef GRUB_UTIL
static grub_err_t
gpt_partition_map_embed (struct grub_disk *disk, unsigned int *nsectors,
+ unsigned int max_nsectors,
grub_embed_type_t embed_type,
grub_disk_addr_t **sectors)
{
@@ -176,6 +177,8 @@
" embedding won't be possible!");
*nsectors = len;
+ if (*nsectors > max_nsectors)
+ *nsectors = max_nsectors;
*sectors = grub_malloc (*nsectors * sizeof (**sectors));
if (!*sectors)
return grub_errno;
Index: b/grub-core/partmap/msdos.c
===================================================================
--- a/grub-core/partmap/msdos.c
+++ b/grub-core/partmap/msdos.c
@@ -29,6 +29,66 @@
static struct grub_partition_map grub_msdos_partition_map;
+#ifdef GRUB_UTIL
+#include <grub/emu/misc.h>
+
+struct embed_signature
+{
+ const char *name;
+ const char *signature;
+ int signature_len;
+ enum { TYPE_SOFTWARE, TYPE_RAID } type;
+};
+
+const char message_warn[][200] = {
+ [TYPE_RAID] = "Sector %llu is already in use by %s; avoiding it. "
+ "Please ask the manufacturer not to store data in MBR gap",
+ [TYPE_SOFTWARE] = "Sector %llu is already in use by %s; avoiding it. "
+ "This software may cause boot or other problems in "
+ "future. Please ask its authors not to store data "
+ "in the boot track"
+};
+
+
+/* Signatures of other software that may be using sectors in the embedding
+ area. */
+struct embed_signature embed_signatures[] =
+ {
+ {
+ .name = "ZISD",
+ .signature = "ZISD",
+ .signature_len = 4,
+ .type = TYPE_SOFTWARE
+ },
+ {
+ .name = "FlexNet",
+ .signature = "\xd4\x41\xa0\xf5\x03\x00\x03\x00",
+ .signature_len = 8,
+ .type = TYPE_SOFTWARE
+ },
+ {
+ .name = "FlexNet",
+ .signature = "\xd8\x41\xa0\xf5\x02\x00\x02\x00",
+ .signature_len = 8,
+ .type = TYPE_SOFTWARE
+ },
+ {
+ /* from Ryan Perkins */
+ .name = "HP Backup and Recovery Manager (?)",
+ .signature = "\x70\x8a\x5d\x46\x35\xc5\x1b\x93"
+ "\xae\x3d\x86\xfd\xb1\x55\x3e\xe0",
+ .signature_len = 16,
+ .type = TYPE_SOFTWARE
+ },
+ {
+ .name = "HighPoint RAID controller",
+ .signature = "ycgl",
+ .signature_len = 4,
+ .type = TYPE_RAID
+ }
+ };
+#endif
+
grub_err_t
grub_partition_msdos_iterate (grub_disk_t disk,
int (*hook) (grub_disk_t disk,
@@ -148,6 +208,7 @@
#ifdef GRUB_UTIL
static grub_err_t
pc_partition_map_embed (struct grub_disk *disk, unsigned int *nsectors,
+ unsigned int max_nsectors,
grub_embed_type_t embed_type,
grub_disk_addr_t **sectors)
{
@@ -236,13 +297,65 @@
if (end >= *nsectors + 2)
{
- unsigned i;
+ unsigned i, j;
+ char *embed_signature_check;
+ unsigned int orig_nsectors, avail_nsectors;
+
+ orig_nsectors = *nsectors;
*nsectors = end - 2;
+ avail_nsectors = *nsectors;
+ if (*nsectors > max_nsectors)
+ *nsectors = max_nsectors;
*sectors = grub_malloc (*nsectors * sizeof (**sectors));
if (!*sectors)
return grub_errno;
for (i = 0; i < *nsectors; i++)
(*sectors)[i] = 1 + i;
+
+ /* Check for software that is already using parts of the embedding
+ * area.
+ */
+ embed_signature_check = grub_malloc (GRUB_DISK_SECTOR_SIZE);
+ for (i = 0; i < *nsectors; i++)
+ {
+ if (grub_disk_read (disk, (*sectors)[i], 0, GRUB_DISK_SECTOR_SIZE,
+ embed_signature_check))
+ continue;
+
+ for (j = 0; j < ARRAY_SIZE (embed_signatures); j++)
+ if (! grub_memcmp (embed_signatures[j].signature,
+ embed_signature_check,
+ embed_signatures[j].signature_len))
+ break;
+ if (j == ARRAY_SIZE (embed_signatures))
+ continue;
+ grub_util_warn (message_warn[embed_signatures[j].type],
+ (*sectors)[i], embed_signatures[j].name);
+ avail_nsectors--;
+ if (avail_nsectors < *nsectors)
+ *nsectors = avail_nsectors;
+
+ /* Avoid this sector. */
+ for (j = i; j < *nsectors; j++)
+ (*sectors)[j]++;
+
+ /* Have we run out of space? */
+ if (avail_nsectors < orig_nsectors)
+ break;
+
+ /* Make sure to check the next sector. */
+ i--;
+ }
+ grub_free (embed_signature_check);
+
+ if (*nsectors < orig_nsectors)
+ return grub_error (GRUB_ERR_OUT_OF_RANGE,
+ "Other software is using the embedding area, and "
+ "there is not enough room for core.img. Such "
+ "software is often trying to store data in a way "
+ "that avoids detection. We recommend you "
+ "investigate.");
+
return GRUB_ERR_NONE;
}
Index: b/include/grub/partition.h
===================================================================
--- a/include/grub/partition.h
+++ b/include/grub/partition.h
@@ -49,6 +49,7 @@
#ifdef GRUB_UTIL
/* Determine sectors available for embedding. */
grub_err_t (*embed) (struct grub_disk *disk, unsigned int *nsectors,
+ unsigned int max_nsectors,
grub_embed_type_t embed_type,
grub_disk_addr_t **sectors);
#endif
Index: b/util/grub-setup.c
===================================================================
--- a/util/grub-setup.c
+++ b/util/grub-setup.c
@@ -428,10 +428,8 @@
}
nsec = core_sectors;
- err = dest_partmap->embed (dest_dev->disk, &nsec,
+ err = dest_partmap->embed (dest_dev->disk, &nsec, 2 * core_sectors,
GRUB_EMBED_PCBIOS, §ors);
- if (nsec > 2 * core_sectors)
- nsec = 2 * core_sectors;
if (err)
{
@@ -460,6 +458,13 @@
save_blocklists (sectors[i] + grub_partition_get_start (container),
0, GRUB_DISK_SECTOR_SIZE);
+ /* Make sure that the last blocklist is a terminator. */
+ if (block == first_block)
+ block--;
+ block->start = 0;
+ block->len = 0;
+ block->segment = 0;
+
write_rootdev (core_img, root_dev, boot_img, first_sector);
core_img = realloc (core_img, nsec * GRUB_DISK_SECTOR_SIZE);
@@ -476,12 +481,6 @@
nsec * GRUB_DISK_SECTOR_SIZE
- core_size);
- /* Make sure that the second blocklist is a terminator. */
- block = first_block - 1;
- block->start = 0;
- block->len = 0;
- block->segment = 0;
-
/* Write the core image onto the disk. */
for (i = 0; i < nsec; i++)
grub_disk_write (dest_dev->disk, sectors[i], 0,
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