Calculate and verify a checksum of the MMP block.
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
debugfs/debugfs.c | 1 +
debugfs/set_fields.c | 1 +
lib/ext2fs/csum.c | 34 ++++++++++++++++++++++++++++++++++
lib/ext2fs/ext2_err.et.in | 3 +++
lib/ext2fs/ext2fs.h | 3 +++
lib/ext2fs/mmp.c | 19 +++++++++++++++++--
lib/ext2fs/swapfs.c | 1 +
7 files changed, 60 insertions(+), 2 deletions(-)
diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c
index 2e46cd5..9c8e48e 100644
--- a/debugfs/debugfs.c
+++ b/debugfs/debugfs.c
@@ -2218,6 +2218,7 @@ void do_dump_mmp(int argc EXT2FS_ATTR((unused)), char *argv[])
fprintf(stdout, "node_name: %s\n", mmp_s->mmp_nodename);
fprintf(stdout, "device_name: %s\n", mmp_s->mmp_bdevname);
fprintf(stdout, "magic: 0x%x\n", mmp_s->mmp_magic);
+ fprintf(stdout, "checksum: 0x%08x\n", mmp_s->mmp_checksum);
}
static int source_file(const char *cmd_file, int sci_idx)
diff --git a/debugfs/set_fields.c b/debugfs/set_fields.c
index 871bf20..986e404 100644
--- a/debugfs/set_fields.c
+++ b/debugfs/set_fields.c
@@ -256,6 +256,7 @@ static struct field_set_info mmp_fields[] = {
{ "bdevname", &set_mmp.mmp_bdevname, NULL, sizeof(set_mmp.mmp_bdevname),
parse_string },
{ "check_interval", &set_mmp.mmp_check_interval, NULL, 2, parse_uint },
+ { "checksum", &set_mmp.mmp_checksum, NULL, 4, parse_uint },
};
static int check_suffix(const char *field)
diff --git a/lib/ext2fs/csum.c b/lib/ext2fs/csum.c
index d4f98e0..425f736 100644
--- a/lib/ext2fs/csum.c
+++ b/lib/ext2fs/csum.c
@@ -30,6 +30,40 @@
#define STATIC static
#endif
+static __u32 ext2fs_mmp_csum(ext2_filsys fs, struct mmp_struct *mmp)
+{
+ int offset = offsetof(struct mmp_struct, mmp_checksum);
+
+ return ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)mmp, offset);
+}
+
+int ext2fs_mmp_csum_verify(ext2_filsys fs, struct mmp_struct *mmp)
+{
+ __u32 calculated;
+
+ if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+ return 1;
+
+ calculated = ext2fs_mmp_csum(fs, mmp);
+
+ return ext2fs_le32_to_cpu(mmp->mmp_checksum) == calculated;
+}
+
+errcode_t ext2fs_mmp_csum_set(ext2_filsys fs, struct mmp_struct *mmp)
+{
+ __u32 crc;
+
+ if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+ return 0;
+
+ crc = ext2fs_mmp_csum(fs, mmp);
+ mmp->mmp_checksum = ext2fs_cpu_to_le32(crc);
+
+ return 0;
+}
+
int ext2fs_verify_csum_type(ext2_filsys fs, struct ext2_super_block *sb)
{
if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
diff --git a/lib/ext2fs/ext2_err.et.in b/lib/ext2fs/ext2_err.et.in
index 01f9f7b..a42ed9a 100644
--- a/lib/ext2fs/ext2_err.et.in
+++ b/lib/ext2fs/ext2_err.et.in
@@ -467,4 +467,7 @@ ec EXT2_ET_SB_CSUM_INVALID,
ec EXT2_ET_UNKNOWN_CSUM,
"Unknown checksum algorithm"
+ec EXT2_ET_MMP_CSUM_INVALID,
+ "MMP block checksum does not match MMP block"
+
end
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index eeac04d..49d9271 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -958,6 +958,8 @@ extern __u32 ext2fs_crc32c_be(__u32 crc, unsigned char const *p, size_t len);
extern __u32 ext2fs_crc32c_le(__u32 crc, unsigned char const *p, size_t len);
/* csum.c */
+extern errcode_t ext2fs_mmp_csum_set(ext2_filsys fs, struct mmp_struct *mmp);
+extern int ext2fs_mmp_csum_verify(ext2_filsys, struct mmp_struct *mmp);
extern int ext2fs_verify_csum_type(ext2_filsys fs, struct ext2_super_block *sb);
extern errcode_t ext2fs_superblock_csum_set(ext2_filsys fs,
struct ext2_super_block *sb);
@@ -1451,6 +1453,7 @@ errcode_t ext2fs_mmp_clear(ext2_filsys fs);
errcode_t ext2fs_mmp_init(ext2_filsys fs);
errcode_t ext2fs_mmp_start(ext2_filsys fs);
errcode_t ext2fs_mmp_update(ext2_filsys fs);
+errcode_t ext2fs_mmp_update2(ext2_filsys fs, int immediately);
errcode_t ext2fs_mmp_stop(ext2_filsys fs);
unsigned ext2fs_mmp_new_seq(void);
diff --git a/lib/ext2fs/mmp.c b/lib/ext2fs/mmp.c
index b27d9a4..20a98f5 100644
--- a/lib/ext2fs/mmp.c
+++ b/lib/ext2fs/mmp.c
@@ -91,6 +91,11 @@ errcode_t ext2fs_mmp_read(ext2_filsys fs, blk64_t mmp_blk, void *buf)
}
mmp_cmp = fs->mmp_cmp;
+
+ if (!(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS) &&
+ !ext2fs_mmp_csum_verify(fs, mmp_cmp))
+ retval = EXT2_ET_MMP_CSUM_INVALID;
+
#ifdef WORDS_BIGENDIAN
ext2fs_swap_mmp(mmp_cmp);
#endif
@@ -125,6 +130,10 @@ errcode_t ext2fs_mmp_write(ext2_filsys fs, blk64_t mmp_blk, void *buf)
ext2fs_swap_mmp(mmp_s);
#endif
+ retval = ext2fs_mmp_csum_set(fs, mmp_s);
+ if (retval)
+ return retval;
+
/* I was tempted to make this use O_DIRECT and the mmp_fd, but
* this caused no end of grief, while leaving it as-is works. */
retval = io_channel_write_blk64(fs->io, mmp_blk, -(int)sizeof(struct mmp_struct), buf);
@@ -381,7 +390,7 @@ mmp_error:
/*
* Update the on-disk mmp buffer, after checking that it hasn't been changed.
*/
-errcode_t ext2fs_mmp_update(ext2_filsys fs)
+errcode_t ext2fs_mmp_update2(ext2_filsys fs, int immediately)
{
struct mmp_struct *mmp, *mmp_cmp;
struct timeval tv;
@@ -392,7 +401,8 @@ errcode_t ext2fs_mmp_update(ext2_filsys fs)
return 0;
gettimeofday(&tv, 0);
- if (tv.tv_sec - fs->mmp_last_written < EXT2_MIN_MMP_UPDATE_INTERVAL)
+ if (!immediately &&
+ tv.tv_sec - fs->mmp_last_written < EXT2_MIN_MMP_UPDATE_INTERVAL)
return 0;
retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, NULL);
@@ -412,3 +422,8 @@ errcode_t ext2fs_mmp_update(ext2_filsys fs)
mmp_error:
return retval;
}
+
+errcode_t ext2fs_mmp_update(ext2_filsys fs)
+{
+ return ext2fs_mmp_update2(fs, 0);
+}
diff --git a/lib/ext2fs/swapfs.c b/lib/ext2fs/swapfs.c
index de178a4..1295e81 100644
--- a/lib/ext2fs/swapfs.c
+++ b/lib/ext2fs/swapfs.c
@@ -349,6 +349,7 @@ void ext2fs_swap_mmp(struct mmp_struct *mmp)
mmp->mmp_seq = ext2fs_swab32(mmp->mmp_seq);
mmp->mmp_time = ext2fs_swab64(mmp->mmp_time);
mmp->mmp_check_interval = ext2fs_swab16(mmp->mmp_check_interval);
+ mmp->mmp_checksum = ext2fs_swab32(mmp->mmp_checksum);
}
errcode_t ext2fs_dirent_swab_in(ext2_filsys fs, char *buf, int flags)
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