* [PATCH] Btrfs-progs: Validate super block checksum
@ 2013-05-29 12:36 Filipe David Borba Manana
2013-06-06 13:51 ` Filipe David Manana
0 siblings, 1 reply; 2+ messages in thread
From: Filipe David Borba Manana @ 2013-05-29 12:36 UTC (permalink / raw)
To: linux-btrfs; +Cc: Filipe David Borba Manana
After finding a super block in a device also validate its
checksum. This validation is done in the kernel but it was
missing in btrfs-progs.
The function btrfs_check_super_csum() is imported from the
file fs/btrfs/disk-io.c in the kernel source tree.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
---
disk-io.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++------------
1 file changed, 62 insertions(+), 14 deletions(-)
diff --git a/disk-io.c b/disk-io.c
index 21b410d..bde58f2 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -1085,47 +1085,95 @@ struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
return info->fs_root;
}
+static int btrfs_check_super_csum(char *raw_disk_sb)
+{
+ struct btrfs_super_block *disk_sb =
+ (struct btrfs_super_block *)raw_disk_sb;
+ u16 csum_type = btrfs_super_csum_type(disk_sb);
+ int ret = 0;
+
+ if (csum_type == BTRFS_CSUM_TYPE_CRC32) {
+ u32 crc = ~(u32)0;
+ const int csum_size = sizeof(crc);
+ char result[csum_size];
+
+ /*
+ * The super_block structure does not span the whole
+ * BTRFS_SUPER_INFO_SIZE range, we expect that the unused space
+ * is filled with zeros and is included in the checkum.
+ */
+ crc = btrfs_csum_data(NULL, raw_disk_sb + BTRFS_CSUM_SIZE,
+ crc, BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
+ btrfs_csum_final(crc, result);
+
+ if (memcmp(raw_disk_sb, result, csum_size))
+ ret = 1;
+
+ if (ret && btrfs_super_generation(disk_sb) < 10) {
+ fprintf(stderr, "btrfs: super block crcs don't match, "
+ "older mkfs detected\n");
+ ret = 0;
+ }
+ }
+
+ if (csum_type >= ARRAY_SIZE(btrfs_csum_sizes)) {
+ fprintf(stderr, "btrfs: unsupported checksum algorithm %u\n",
+ csum_type);
+ ret = 1;
+ }
+
+ return ret;
+}
+
int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr)
{
u8 fsid[BTRFS_FSID_SIZE];
int fsid_is_initialized = 0;
- struct btrfs_super_block buf;
+ char buf[BTRFS_SUPER_INFO_SIZE];
+ struct btrfs_super_block *tmp_sb;
int i;
int ret;
u64 transid = 0;
u64 bytenr;
if (sb_bytenr != BTRFS_SUPER_INFO_OFFSET) {
- ret = pread64(fd, &buf, sizeof(buf), sb_bytenr);
+ ret = pread64(fd, buf, sizeof(buf), sb_bytenr);
if (ret < sizeof(buf))
return -1;
- if (btrfs_super_bytenr(&buf) != sb_bytenr ||
- buf.magic != cpu_to_le64(BTRFS_MAGIC))
+ tmp_sb = (struct btrfs_super_block *)buf;
+
+ if (btrfs_super_bytenr(tmp_sb) != sb_bytenr ||
+ tmp_sb->magic != cpu_to_le64(BTRFS_MAGIC) ||
+ btrfs_check_super_csum(buf))
return -1;
- memcpy(sb, &buf, sizeof(*sb));
+ memcpy(sb, buf, sizeof(*sb));
return 0;
}
for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
bytenr = btrfs_sb_offset(i);
- ret = pread64(fd, &buf, sizeof(buf), bytenr);
+ ret = pread64(fd, buf, sizeof(buf), bytenr);
if (ret < sizeof(buf))
break;
- if (btrfs_super_bytenr(&buf) != bytenr )
+ tmp_sb = (struct btrfs_super_block *)buf;
+
+ if (btrfs_super_bytenr(tmp_sb) != bytenr )
continue;
/* if magic is NULL, the device was removed */
- if (buf.magic == 0 && i == 0)
+ if (tmp_sb->magic == 0 && i == 0)
return -1;
- if (buf.magic != cpu_to_le64(BTRFS_MAGIC))
+ if (tmp_sb->magic != cpu_to_le64(BTRFS_MAGIC))
+ continue;
+ if (btrfs_check_super_csum(buf))
continue;
if (!fsid_is_initialized) {
- memcpy(fsid, buf.fsid, sizeof(fsid));
+ memcpy(fsid, tmp_sb->fsid, sizeof(fsid));
fsid_is_initialized = 1;
- } else if (memcmp(fsid, buf.fsid, sizeof(fsid))) {
+ } else if (memcmp(fsid, tmp_sb->fsid, sizeof(fsid))) {
/*
* the superblocks (the original one and
* its backups) contain data of different
@@ -1134,9 +1182,9 @@ int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr)
continue;
}
- if (btrfs_super_generation(&buf) > transid) {
- memcpy(sb, &buf, sizeof(*sb));
- transid = btrfs_super_generation(&buf);
+ if (btrfs_super_generation(tmp_sb) > transid) {
+ memcpy(sb, buf, sizeof(*sb));
+ transid = btrfs_super_generation(tmp_sb);
}
}
--
1.7.9.5
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] Btrfs-progs: Validate super block checksum
2013-05-29 12:36 [PATCH] Btrfs-progs: Validate super block checksum Filipe David Borba Manana
@ 2013-06-06 13:51 ` Filipe David Manana
0 siblings, 0 replies; 2+ messages in thread
From: Filipe David Manana @ 2013-06-06 13:51 UTC (permalink / raw)
To: linux-btrfs
Hello,
Any feedback?
thanks
On Wed, May 29, 2013 at 1:36 PM, Filipe David Borba Manana
<fdmanana@gmail.com> wrote:
> After finding a super block in a device also validate its
> checksum. This validation is done in the kernel but it was
> missing in btrfs-progs.
>
> The function btrfs_check_super_csum() is imported from the
> file fs/btrfs/disk-io.c in the kernel source tree.
>
> Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
> ---
> disk-io.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++------------
> 1 file changed, 62 insertions(+), 14 deletions(-)
>
> diff --git a/disk-io.c b/disk-io.c
> index 21b410d..bde58f2 100644
> --- a/disk-io.c
> +++ b/disk-io.c
> @@ -1085,47 +1085,95 @@ struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
> return info->fs_root;
> }
>
> +static int btrfs_check_super_csum(char *raw_disk_sb)
> +{
> + struct btrfs_super_block *disk_sb =
> + (struct btrfs_super_block *)raw_disk_sb;
> + u16 csum_type = btrfs_super_csum_type(disk_sb);
> + int ret = 0;
> +
> + if (csum_type == BTRFS_CSUM_TYPE_CRC32) {
> + u32 crc = ~(u32)0;
> + const int csum_size = sizeof(crc);
> + char result[csum_size];
> +
> + /*
> + * The super_block structure does not span the whole
> + * BTRFS_SUPER_INFO_SIZE range, we expect that the unused space
> + * is filled with zeros and is included in the checkum.
> + */
> + crc = btrfs_csum_data(NULL, raw_disk_sb + BTRFS_CSUM_SIZE,
> + crc, BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
> + btrfs_csum_final(crc, result);
> +
> + if (memcmp(raw_disk_sb, result, csum_size))
> + ret = 1;
> +
> + if (ret && btrfs_super_generation(disk_sb) < 10) {
> + fprintf(stderr, "btrfs: super block crcs don't match, "
> + "older mkfs detected\n");
> + ret = 0;
> + }
> + }
> +
> + if (csum_type >= ARRAY_SIZE(btrfs_csum_sizes)) {
> + fprintf(stderr, "btrfs: unsupported checksum algorithm %u\n",
> + csum_type);
> + ret = 1;
> + }
> +
> + return ret;
> +}
> +
> int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr)
> {
> u8 fsid[BTRFS_FSID_SIZE];
> int fsid_is_initialized = 0;
> - struct btrfs_super_block buf;
> + char buf[BTRFS_SUPER_INFO_SIZE];
> + struct btrfs_super_block *tmp_sb;
> int i;
> int ret;
> u64 transid = 0;
> u64 bytenr;
>
> if (sb_bytenr != BTRFS_SUPER_INFO_OFFSET) {
> - ret = pread64(fd, &buf, sizeof(buf), sb_bytenr);
> + ret = pread64(fd, buf, sizeof(buf), sb_bytenr);
> if (ret < sizeof(buf))
> return -1;
>
> - if (btrfs_super_bytenr(&buf) != sb_bytenr ||
> - buf.magic != cpu_to_le64(BTRFS_MAGIC))
> + tmp_sb = (struct btrfs_super_block *)buf;
> +
> + if (btrfs_super_bytenr(tmp_sb) != sb_bytenr ||
> + tmp_sb->magic != cpu_to_le64(BTRFS_MAGIC) ||
> + btrfs_check_super_csum(buf))
> return -1;
>
> - memcpy(sb, &buf, sizeof(*sb));
> + memcpy(sb, buf, sizeof(*sb));
> return 0;
> }
>
> for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
> bytenr = btrfs_sb_offset(i);
> - ret = pread64(fd, &buf, sizeof(buf), bytenr);
> + ret = pread64(fd, buf, sizeof(buf), bytenr);
> if (ret < sizeof(buf))
> break;
>
> - if (btrfs_super_bytenr(&buf) != bytenr )
> + tmp_sb = (struct btrfs_super_block *)buf;
> +
> + if (btrfs_super_bytenr(tmp_sb) != bytenr )
> continue;
> /* if magic is NULL, the device was removed */
> - if (buf.magic == 0 && i == 0)
> + if (tmp_sb->magic == 0 && i == 0)
> return -1;
> - if (buf.magic != cpu_to_le64(BTRFS_MAGIC))
> + if (tmp_sb->magic != cpu_to_le64(BTRFS_MAGIC))
> + continue;
> + if (btrfs_check_super_csum(buf))
> continue;
>
> if (!fsid_is_initialized) {
> - memcpy(fsid, buf.fsid, sizeof(fsid));
> + memcpy(fsid, tmp_sb->fsid, sizeof(fsid));
> fsid_is_initialized = 1;
> - } else if (memcmp(fsid, buf.fsid, sizeof(fsid))) {
> + } else if (memcmp(fsid, tmp_sb->fsid, sizeof(fsid))) {
> /*
> * the superblocks (the original one and
> * its backups) contain data of different
> @@ -1134,9 +1182,9 @@ int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr)
> continue;
> }
>
> - if (btrfs_super_generation(&buf) > transid) {
> - memcpy(sb, &buf, sizeof(*sb));
> - transid = btrfs_super_generation(&buf);
> + if (btrfs_super_generation(tmp_sb) > transid) {
> + memcpy(sb, buf, sizeof(*sb));
> + transid = btrfs_super_generation(tmp_sb);
> }
> }
>
> --
> 1.7.9.5
>
--
Filipe David Manana,
"Reasonable men adapt themselves to the world.
Unreasonable men adapt the world to themselves.
That's why all progress depends on unreasonable men."
^ permalink raw reply [flat|nested] 2+ messages in thread
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2013-05-29 12:36 [PATCH] Btrfs-progs: Validate super block checksum Filipe David Borba Manana
2013-06-06 13:51 ` Filipe David Manana
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