On 2011-08-31, at 6:35 PM, "Darrick J. Wong" <djwong@xxxxxxxxxx> wrote:
> This patch adds the ability for the libext2fs functions to read and write the
> inode checksum. It also fixes a few fields that were omitted from the byte
> swapping routines.
>
> Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> ---
> lib/ext2fs/csum.c | 59 +++++++++++++++++++++++++++++++++++++++++++++
> lib/ext2fs/ext2_err.et.in | 9 +++++++
> lib/ext2fs/ext2_fs.h | 4 ++-
> lib/ext2fs/ext2fs.h | 6 +++++
> lib/ext2fs/inode.c | 20 +++++++++++++++
> lib/ext2fs/swapfs.c | 10 ++++++--
> 6 files changed, 104 insertions(+), 4 deletions(-)
>
>
> diff --git a/lib/ext2fs/csum.c b/lib/ext2fs/csum.c
> index 2fece68..57adc4c 100644
> --- a/lib/ext2fs/csum.c
> +++ b/lib/ext2fs/csum.c
> @@ -29,6 +29,65 @@
> #define STATIC static
> #endif
>
> +__u32 ext2fs_inode_csum(ext2_filsys fs, ext2_ino_t inum,
> + struct ext2_inode_large *inode)
> +{
> + struct ext2_inode_large *desc = inode;
> + int offset = offsetof(struct ext2_inode_large, i_checksum);
> + int extra_size = inode->i_extra_isize;
> + size_t size = fs->super->s_inode_size;
> + __u32 crc = 0;
> +
> + if (size < EXT2_GOOD_OLD_INODE_SIZE + extra_size)
> + printf("ERROR: inode %d size %d != extra_size %d!\n", inum,
> + size, extra_size + EXT2_GOOD_OLD_INODE_SIZE);
This shouldn't have to be checked for every inode checksum. If the checksum is covering the whole inode size then this is a constant size, and e2fsck is already checking the value of i_extra_isize.
> + if (fs->super->s_creator_os != EXT2_OS_LINUX)
> + return 0;
> +
> + if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
> + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
> +
> + return 0;
> +
> +#ifdef WORDS_BIGENDIAN
> + char buf[EXT2_INODE_CORE_SIZE(fs->super)];
> + struct ext2_inode_large *swabinode = (struct ext2_inode_large *)buf;
> +
> + /* Have to swab back to little-endian to do the checksum */
> + memcpy(swabinode, inode, size);
> + ext2fs_swap_inode_full(fs, swabinode, swabinode, 1, size);
> + desc = swabinode;
> +#endif
> + inum = ext2fs_cpu_to_le32(inum);
> + crc = crc32c_le(~0, fs->super->s_uuid, sizeof(fs->super->s_uuid));
> + crc = crc32c_le(crc, (char *)&inum, sizeof(inum));
> + crc = crc32c_le(crc, (char *)desc, offset);
> + offset += sizeof(inode->i_checksum); /* skip checksum */
> + crc = crc32c_le(crc, (char *)desc + offset,
> + EXT2_GOOD_OLD_INODE_SIZE + extra_size - offset);
> + return crc;
> +}
> +
> +int ext2fs_inode_csum_verify(ext2_filsys fs, ext2_ino_t inum,
> + struct ext2_inode_large *inode)
> +{
> + if (fs->super->s_creator_os == EXT2_OS_LINUX &&
> + EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
> + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) &&
> + (inode->i_checksum != ext2fs_inode_csum(fs, inum, inode)))
> + return 0;
> + return 1;
> +}
> +
> +void ext2fs_inode_csum_set(ext2_filsys fs, ext2_ino_t inum,
> + struct ext2_inode_large *inode)
> +{
> + if (fs->super->s_creator_os != EXT2_OS_LINUX)
> + return;
> + inode->i_checksum = ext2fs_inode_csum(fs, inum, inode);
> +}
> +
> STATIC __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
> {
> __u16 crc = 0;
> diff --git a/lib/ext2fs/ext2_err.et.in b/lib/ext2fs/ext2_err.et.in
> index 995ddc3..31c8fe1 100644
> --- a/lib/ext2fs/ext2_err.et.in
> +++ b/lib/ext2fs/ext2_err.et.in
> @@ -422,4 +422,13 @@ ec EXT2_NO_MTAB_FILE,
> ec EXT2_ET_CANT_USE_LEGACY_BITMAPS,
> "Filesystem too large to use legacy bitmaps"
>
> +ec EXT2_ET_INODE_CSUM_INVALID,
> + "Inode checksum is incorrect"
> +
> +ec EXT2_ET_INODE_CORRUPT,
> + "Inode checksum indicates corruption"
> +
> +ec EXT2_ET_INODE_CSUM_NONZERO,
> + "Inode checksum should not be set"
> +
> end
> diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h
> index ae7662e..1f08673 100644
> --- a/lib/ext2fs/ext2_fs.h
> +++ b/lib/ext2fs/ext2_fs.h
> @@ -362,7 +362,7 @@ struct ext2_inode_large {
> __u16 l_i_file_acl_high;
> __u16 l_i_uid_high; /* these 2 fields */
> __u16 l_i_gid_high; /* were reserved2[0] */
> - __u32 l_i_reserved2;
> + __u32 l_i_checksum; /* crc32c(uuid+inum+inode) */
> } linux2;
> struct {
> __u8 h_i_frag; /* Fragment number */
> @@ -393,7 +393,7 @@ struct ext2_inode_large {
> #define i_gid_low i_gid
> #define i_uid_high osd2.linux2.l_i_uid_high
> #define i_gid_high osd2.linux2.l_i_gid_high
> -#define i_reserved2 osd2.linux2.l_i_reserved2
> +#define i_checksum osd2.linux2.l_i_checksum
> #else
> #if defined(__GNU__)
>
> diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
> index e571508..db8b28b 100644
> --- a/lib/ext2fs/ext2fs.h
> +++ b/lib/ext2fs/ext2fs.h
> @@ -892,6 +892,12 @@ extern __u32 crc32c_be(__u32 crc, unsigned char const *p, size_t len);
> extern __u32 crc32c_le(__u32 crc, unsigned char const *p, size_t len);
>
> /* csum.c */
> +extern __u32 ext2fs_inode_csum(ext2_filsys fs, ext2_ino_t inum,
> + struct ext2_inode_large *inode);
> +extern void ext2fs_inode_csum_set(ext2_filsys fs, ext2_ino_t inum,
> + struct ext2_inode_large *inode);
> +extern int ext2fs_inode_csum_verify(ext2_filsys fs, ext2_ino_t inum,
> + struct ext2_inode_large *inode);
> extern void ext2fs_group_desc_csum_set(ext2_filsys fs, dgrp_t group);
> extern int ext2fs_group_desc_csum_verify(ext2_filsys fs, dgrp_t group);
> extern errcode_t ext2fs_set_gdt_csum(ext2_filsys fs);
> diff --git a/lib/ext2fs/inode.c b/lib/ext2fs/inode.c
> index 76893fd..0789505 100644
> --- a/lib/ext2fs/inode.c
> +++ b/lib/ext2fs/inode.c
> @@ -509,6 +509,12 @@ errcode_t ext2fs_get_next_inode_full(ext2_inode_scan scan, ext2_ino_t *ino,
> if (EXT2_INODE_SIZE(scan->fs->super) == EXT2_GOOD_OLD_INODE_SIZE)
> inode->i_extra_isize = 0;
>
> + /* Verify the inode checksum. */
> + if (!(scan->fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS) &&
> + !ext2fs_inode_csum_verify(scan->fs, scan->current_inode, inode))
> + return EXT2_ET_INODE_CSUM_INVALID;
> +
> +
> scan->inodes_left--;
> scan->current_inode++;
> *ino = scan->current_inode;
> @@ -617,6 +623,10 @@ errcode_t ext2fs_read_inode_full(ext2_filsys fs, ext2_ino_t ino,
> (struct ext2_inode_large *) inode,
> 0, bufsize);
> #endif
> + /* Verify the inode checksum. */
> + if (!(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS) &&
> + !ext2fs_inode_csum_verify(fs, ino, inode))
> + return EXT2_ET_INODE_CSUM_INVALID;
>
> /* Update the inode cache */
> fs->icache->cache_last = (fs->icache->cache_last + 1) %
> @@ -685,6 +695,16 @@ errcode_t ext2fs_write_inode_full(ext2_filsys fs, ext2_ino_t ino,
> w_inode = &temp_inode;
> memset(w_inode, 0, length);
>
> + /*
> + * If inode checksum enabled, ensure that we actually have the whole
> + * inode in memory.
> + */
> + if (EXT2_INODE_SIZE(fs->super) > EXT2_GOOD_OLD_INODE_SIZE &&
> + bufsize <= EXT2_GOOD_OLD_INODE_SIZE) {
> + fprintf(stderr, "inode %d has a too-short buffer!\n", ino);
> + abort();
> + }
> + ext2fs_inode_csum_set(fs, ino, inode);
> #ifdef WORDS_BIGENDIAN
> ext2fs_swap_inode_full(fs, w_inode, inode, 1, bufsize);
> #else
> diff --git a/lib/ext2fs/swapfs.c b/lib/ext2fs/swapfs.c
> index 517f1d7..df604ba 100644
> --- a/lib/ext2fs/swapfs.c
> +++ b/lib/ext2fs/swapfs.c
> @@ -244,8 +244,7 @@ void ext2fs_swap_inode_full(ext2_filsys fs, struct ext2_inode_large *t,
> ext2fs_swab16 (f->osd2.linux2.l_i_uid_high);
> t->osd2.linux2.l_i_gid_high =
> ext2fs_swab16 (f->osd2.linux2.l_i_gid_high);
> - t->osd2.linux2.l_i_reserved2 =
> - ext2fs_swab32(f->osd2.linux2.l_i_reserved2);
> + t->i_checksum = ext2fs_swab32(f->i_checksum);
> break;
> case EXT2_OS_HURD:
> t->osd1.hurd1.h_i_translator =
> @@ -279,6 +278,13 @@ void ext2fs_swap_inode_full(ext2_filsys fs, struct ext2_inode_large *t,
> return;
> }
>
> + t->i_ctime_extra = ext2fs_swab32(f->i_ctime_extra);
> + t->i_mtime_extra = ext2fs_swab32(f->i_mtime_extra);
> + t->i_atime_extra = ext2fs_swab32(f->i_atime_extra);
> + t->i_crtime = ext2fs_swab32(f->i_crtime);
> + t->i_crtime_extra = ext2fs_swab32(f->i_crtime_extra);
> + t->i_version_hi = ext2fs_swab32(f->i_version_hi);
> +
> i = EXT2_GOOD_OLD_INODE_SIZE + extra_isize + sizeof(__u32);
> if (bufsize < (int) i)
> return; /* no space for EA magic */
>
> --
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