[PATCH] Enforce inherent limitations of the dos partition table format.
Jim Meyering
meyering at redhat.com
Thu Jan 10 13:51:56 UTC 2008
* libparted/disk.c (_check_partition): Enforce the 32-bit limitation
on a partition's starting sector number and length (in sectors).
With the usual 512-byte sector size, this limits the maximum
partition size to just under 2TB.
* tests/t4100-msdos-partition-limits.sh: New file. Test the above.
* tests/Makefile.am (TESTS): Add t4100-msdos-partition-limits.sh.
Signed-off-by: Jim Meyering <meyering at redhat.com>
---
libparted/disk.c | 41 ++++++++-
tests/Makefile.am | 3 +-
tests/t4100-msdos-partition-limits.sh | 169 +++++++++++++++++++++++++++++++++
3 files changed, 211 insertions(+), 2 deletions(-)
create mode 100755 tests/t4100-msdos-partition-limits.sh
diff --git a/libparted/disk.c b/libparted/disk.c
index 087fbbf..135e230 100644
--- a/libparted/disk.c
+++ b/libparted/disk.c
@@ -1,6 +1,6 @@
/*
libparted - a library for manipulating disk partitions
- Copyright (C) 1999, 2000, 2001, 2002, 2003, 2005, 2007
+ Copyright (C) 1999, 2000, 2001, 2002, 2003, 2005, 2007, 2008
Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
@@ -1735,6 +1735,45 @@ _check_partition (PedDisk* disk, PedPartition* part)
return 0;
}
+ if (!(part->type & PED_PARTITION_METADATA)
+ && strcmp (disk->type->name, "msdos") == 0) {
+ /* Enforce some restrictions inherent in the DOS
+ partition table format. Without these, one would be able
+ to create a 2TB partition (or larger), and it would work,
+ but only until the next reboot. This was insidious: the
+ too-large partition would work initially, because with
+ Linux-2.4.x and newer we set the partition start sector
+ and length (in sectors) accurately and directly via the
+ BLKPG ioctl. However, only the last 32 bits of each
+ number would be written to the partition table, and the
+ next time the system would read/use those corrupted numbers
+ it would usually complain about an invalid partition.
+ The same applies to the starting sector number. */
+
+ /* The partition length, in sectors, must fit in 32 bytes. */
+ if (part->geom.length > UINT32_MAX) {
+ ped_exception_throw (
+ PED_EXCEPTION_ERROR,
+ PED_EXCEPTION_CANCEL,
+ _("partition length of %jd sectors exceeds"
+ " the DOS-partition-table-imposed maximum"
+ " of 2^32-1"),
+ part->geom.length);
+ return 0;
+ }
+
+ /* The starting sector number must fit in 32 bytes. */
+ if (part->geom.start > UINT32_MAX) {
+ ped_exception_throw (
+ PED_EXCEPTION_ERROR,
+ PED_EXCEPTION_CANCEL,
+ _("starting sector number, %jd exceeds"
+ " the DOS-partition-table-imposed maximum"
+ " of 2^32-1"), part->geom.start);
+ return 0;
+ }
+ }
+
return 1;
}
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 3a3020e..b9cd205 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -7,7 +7,8 @@ TESTS = \
t2000-mkfs.sh \
t2100-mkswap.sh \
t3000-constraints.sh \
- t3100-resize-ext2-partion.sh
+ t3100-resize-ext2-partion.sh \
+ t4100-msdos-partition-limits.sh
EXTRA_DIST = \
$(TESTS) test-lib.sh mkdtemp
diff --git a/tests/t4100-msdos-partition-limits.sh b/tests/t4100-msdos-partition-limits.sh
new file mode 100755
index 0000000..13e32af
--- /dev/null
+++ b/tests/t4100-msdos-partition-limits.sh
@@ -0,0 +1,169 @@
+#!/bin/sh
+
+# Copyright (C) 2008 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+test_description='msdos: enforce limits on partition start sector and length'
+
+# Need root privileges to use mount.
+privileges_required_=1
+
+. ./init.sh
+
+####################################################
+# Create and mount a file system capable of dealing with >=2TB files.
+# We must be able to create a file with an apparent length of 2TB or larger.
+# It needn't be a large file system.
+fs=fs_file
+mp=`pwd`/mount-point
+n=128
+
+test_expect_success \
+ 'create an XFS file system' \
+ '
+ dd if=/dev/zero of=$fs bs=1MB count=2 seek=20 &&
+ mkfs.xfs -q $fs &&
+ mkdir "$mp"
+
+ '
+
+# Unmount upon interrupt, failure, etc., as well as upon normal completion.
+cleanup_() { cd "$test_dir_" && umount "$mp" > /dev/null 2>&1; }
+
+test_expect_success \
+ 'mount it' \
+ '
+ mount -o loop $fs "$mp" &&
+ cd "$mp"
+
+ '
+dev=loop-file
+
+do_mkpart()
+{
+ start_sector=$1
+ end_sector=$2
+ # echo '********' $(echo $end_sector - $start_sector + 1 |bc)
+ dd if=/dev/zero of=$dev bs=1b count=2k seek=$end_sector 2> /dev/null &&
+ parted -s $dev mklabel msdos &&
+ parted -s $dev mkpart p xfs ${start_sector}s ${end_sector}s
+}
+
+# Specify the starting sector number and length in sectors,
+# rather than start and end.
+do_mkpart_start_and_len()
+{
+ start_sector=$1
+ len=$2
+ end_sector=$(echo $start_sector + $len - 1|bc)
+ do_mkpart $start_sector $end_sector
+}
+
+test_expect_success \
+ 'a partition length of 2^32-1 works.' \
+ '
+ end=$(echo $n+2^32-2|bc) &&
+ do_mkpart $n $end
+ '
+
+cat > exp <<EOF
+Model: (file)
+Disk: 4294969470s
+Sector size (logical/physical): 512B/512B
+Partition Table: msdos
+
+Number Start End Size Type File system Flags
+ 1 ${n}s ${end}s 4294967295s primary
+
+EOF
+
+test_expect_success \
+ 'print the result' \
+ 'parted -s $dev unit s p > out 2>&1 &&
+ sed "s/Disk .*:/Disk:/;s/ *$//" out > k && mv k out &&
+ diff -u out exp
+ '
+
+test_expect_failure \
+ 'a partition length of exactly 2^32 sectors provokes failure.' \
+ 'do_mkpart $n $(echo $n+2^32-1|bc) > err 2>&1'
+
+msg='Error: partition length of 4294967296 sectors exceeds the '\
+'DOS-partition-table-imposed maximum of 2^32-1'
+test_expect_success \
+ 'check for new diagnostic' \
+ 'echo "$msg" > exp && diff -u err exp'
+
+# FIXME: investigate this.
+# Unexpectedly to me, both of these failed with this same diagnostic:
+#
+# Error: partition length of 4294967296 sectors exceeds the \
+# DOS-partition-table-imposed maximum of 2^32-1" > exp &&
+#
+# I expected the one below to fail with a length of _4294967297_.
+# Debugging, I see that _check_partition *does* detect this,
+# but the diagnostic doesn't get displayed because of the wonders
+# of parted's exception mechanism.
+
+test_expect_failure \
+ 'a partition length of 2^32+1 sectors provokes failure.' \
+ 'do_mkpart $n $(echo $n+2^32|bc) > err 2>&1'
+
+test_expect_success \
+ 'check for new diagnostic' \
+ 'echo "$msg" > exp && diff -u err exp'
+
+# =========================================================
+# Now consider partition starting sector numbers.
+msg='Error: starting sector number, 4294967296 exceeds the '\
+'DOS-partition-table-imposed maximum of 2^32-1'
+
+test_expect_success \
+ 'a partition start sector number of 2^32-1 works.' \
+ 'do_mkpart_start_and_len $(echo 2^32-1|bc) 1000'
+
+cat > exp <<EOF
+Model: (file)
+Disk: 4294970342s
+Sector size (logical/physical): 512B/512B
+Partition Table: msdos
+
+Number Start End Size Type File system Flags
+ 1 4294967295s 4294968294s 1000s primary
+
+EOF
+
+test_expect_success \
+ 'print the result' \
+ 'parted -s $dev unit s p > out 2>&1 &&
+ sed "s/Disk .*:/Disk:/;s/ *$//" out > k && mv k out &&
+ diff -u out exp
+ '
+
+test_expect_failure \
+ 'a partition start sector number of 2^32 must fail.' \
+ 'do_mkpart_start_and_len $(echo 2^32|bc) 1000 > err 2>&1'
+test_expect_success \
+ 'check for new diagnostic' \
+ 'echo "$msg" > exp && diff -u err exp'
+
+test_expect_failure \
+ 'a partition start sector number of 2^32+1 must fail, too.' \
+ 'do_mkpart_start_and_len $(echo 2^32+1|bc) 1000 > err 2>&1'
+test_expect_success \
+ 'check for new diagnostic' \
+ 'echo "$msg" > exp && diff -u err exp'
+
+test_done
--
1.5.4.rc2.85.g71fd
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