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xfs: refactor superblock verifiers
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Split the superblock verifier into the common checks, the read-time
checks, and the write-time check functions.  No functional changes, but
we're setting up to add more write-only checks.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
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Darrick J. Wong committed Jul 31, 2018
1 parent 86d969b commit eca383f
Showing 1 changed file with 111 additions and 94 deletions.
205 changes: 111 additions & 94 deletions fs/xfs/libxfs/xfs_sb.c
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Original file line number Diff line number Diff line change
Expand Up @@ -96,80 +96,94 @@ xfs_perag_put(
trace_xfs_perag_put(pag->pag_mount, pag->pag_agno, ref, _RET_IP_);
}

/*
* Check the validity of the SB found.
*/
/* Check all the superblock fields we care about when reading one in. */
STATIC int
xfs_mount_validate_sb(
xfs_mount_t *mp,
xfs_sb_t *sbp,
bool check_inprogress,
bool check_version)
xfs_validate_sb_read(
struct xfs_mount *mp,
struct xfs_sb *sbp)
{
uint32_t agcount = 0;
uint32_t rem;

if (sbp->sb_magicnum != XFS_SB_MAGIC) {
xfs_warn(mp, "bad magic number");
return -EWRONGFS;
}


if (!xfs_sb_good_version(sbp)) {
xfs_warn(mp, "bad version");
return -EWRONGFS;
}
if (XFS_SB_VERSION_NUM(sbp) != XFS_SB_VERSION_5)
return 0;

/*
* Version 5 superblock feature mask validation. Reject combinations the
* kernel cannot support up front before checking anything else. For
* write validation, we don't need to check feature masks.
* Version 5 superblock feature mask validation. Reject combinations
* the kernel cannot support up front before checking anything else.
*/
if (check_version && XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5) {
if (xfs_sb_has_compat_feature(sbp,
XFS_SB_FEAT_COMPAT_UNKNOWN)) {
xfs_warn(mp,
if (xfs_sb_has_compat_feature(sbp, XFS_SB_FEAT_COMPAT_UNKNOWN)) {
xfs_warn(mp,
"Superblock has unknown compatible features (0x%x) enabled.",
(sbp->sb_features_compat &
XFS_SB_FEAT_COMPAT_UNKNOWN));
xfs_warn(mp,
(sbp->sb_features_compat & XFS_SB_FEAT_COMPAT_UNKNOWN));
xfs_warn(mp,
"Using a more recent kernel is recommended.");
}
}

if (xfs_sb_has_ro_compat_feature(sbp,
XFS_SB_FEAT_RO_COMPAT_UNKNOWN)) {
xfs_alert(mp,
if (xfs_sb_has_ro_compat_feature(sbp, XFS_SB_FEAT_RO_COMPAT_UNKNOWN)) {
xfs_alert(mp,
"Superblock has unknown read-only compatible features (0x%x) enabled.",
(sbp->sb_features_ro_compat &
XFS_SB_FEAT_RO_COMPAT_UNKNOWN));
if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
xfs_warn(mp,
(sbp->sb_features_ro_compat &
XFS_SB_FEAT_RO_COMPAT_UNKNOWN));
if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
xfs_warn(mp,
"Attempted to mount read-only compatible filesystem read-write.");
xfs_warn(mp,
xfs_warn(mp,
"Filesystem can only be safely mounted read only.");

return -EINVAL;
}
}
if (xfs_sb_has_incompat_feature(sbp,
XFS_SB_FEAT_INCOMPAT_UNKNOWN)) {
xfs_warn(mp,
"Superblock has unknown incompatible features (0x%x) enabled.",
(sbp->sb_features_incompat &
XFS_SB_FEAT_INCOMPAT_UNKNOWN));
xfs_warn(mp,
"Filesystem can not be safely mounted by this kernel.");
return -EINVAL;
}
} else if (xfs_sb_version_hascrc(sbp)) {
/*
* We can't read verify the sb LSN because the read verifier is
* called before the log is allocated and processed. We know the
* log is set up before write verifier (!check_version) calls,
* so just check it here.
*/
if (!xfs_log_check_lsn(mp, sbp->sb_lsn))
return -EFSCORRUPTED;
}
if (xfs_sb_has_incompat_feature(sbp, XFS_SB_FEAT_INCOMPAT_UNKNOWN)) {
xfs_warn(mp,
"Superblock has unknown incompatible features (0x%x) enabled.",
(sbp->sb_features_incompat &
XFS_SB_FEAT_INCOMPAT_UNKNOWN));
xfs_warn(mp,
"Filesystem cannot be safely mounted by this kernel.");
return -EINVAL;
}

return 0;
}

/* Check all the superblock fields we care about when writing one out. */
STATIC int
xfs_validate_sb_write(
struct xfs_mount *mp,
struct xfs_sb *sbp)
{
if (XFS_SB_VERSION_NUM(sbp) != XFS_SB_VERSION_5)
return 0;

/* XXX: For write validation, we don't need to check feature masks?? */

/*
* We can't read verify the sb LSN because the read verifier is called
* before the log is allocated and processed. We know the log is set up
* before write verifier calls, so check it here.
*/
if (!xfs_log_check_lsn(mp, sbp->sb_lsn))
return -EFSCORRUPTED;

return 0;
}

/* Check the validity of the SB. */
STATIC int
xfs_validate_sb_common(
struct xfs_mount *mp,
struct xfs_buf *bp,
struct xfs_sb *sbp)
{
uint32_t agcount = 0;
uint32_t rem;

if (sbp->sb_magicnum != XFS_SB_MAGIC) {
xfs_warn(mp, "bad magic number");
return -EWRONGFS;
}

if (!xfs_sb_good_version(sbp)) {
xfs_warn(mp, "bad version");
return -EWRONGFS;
}

if (xfs_sb_version_has_pquotino(sbp)) {
Expand Down Expand Up @@ -321,7 +335,12 @@ xfs_mount_validate_sb(
return -EFBIG;
}

if (check_inprogress && sbp->sb_inprogress) {
/*
* Don't touch the filesystem if a user tool thinks it owns the primary
* superblock. mkfs doesn't clear the flag from secondary supers, so
* we don't check them at all.
*/
if (XFS_BUF_ADDR(bp) == XFS_SB_DADDR && sbp->sb_inprogress) {
xfs_warn(mp, "Offline file system operation in progress!");
return -EFSCORRUPTED;
}
Expand Down Expand Up @@ -596,29 +615,6 @@ xfs_sb_to_disk(
}
}

static int
xfs_sb_verify(
struct xfs_buf *bp,
bool check_version)
{
struct xfs_mount *mp = bp->b_target->bt_mount;
struct xfs_sb sb;

/*
* Use call variant which doesn't convert quota flags from disk
* format, because xfs_mount_validate_sb checks the on-disk flags.
*/
__xfs_sb_from_disk(&sb, XFS_BUF_TO_SBP(bp), false);

/*
* Only check the in progress field for the primary superblock as
* mkfs.xfs doesn't clear it from secondary superblocks.
*/
return xfs_mount_validate_sb(mp, &sb,
bp->b_maps[0].bm_bn == XFS_SB_DADDR,
check_version);
}

/*
* If the superblock has the CRC feature bit set or the CRC field is non-null,
* check that the CRC is valid. We check the CRC field is non-null because a
Expand All @@ -633,11 +629,12 @@ xfs_sb_verify(
*/
static void
xfs_sb_read_verify(
struct xfs_buf *bp)
struct xfs_buf *bp)
{
struct xfs_mount *mp = bp->b_target->bt_mount;
struct xfs_dsb *dsb = XFS_BUF_TO_SBP(bp);
int error;
struct xfs_sb sb;
struct xfs_mount *mp = bp->b_target->bt_mount;
struct xfs_dsb *dsb = XFS_BUF_TO_SBP(bp);
int error;

/*
* open code the version check to avoid needing to convert the entire
Expand All @@ -657,7 +654,16 @@ xfs_sb_read_verify(
}
}
}
error = xfs_sb_verify(bp, true);

/*
* Check all the superblock fields. Don't byteswap the xquota flags
* because _verify_common checks the on-disk values.
*/
__xfs_sb_from_disk(&sb, XFS_BUF_TO_SBP(bp), false);
error = xfs_validate_sb_common(mp, bp, &sb);
if (error)
goto out_error;
error = xfs_validate_sb_read(mp, &sb);

out_error:
if (error == -EFSCORRUPTED || error == -EFSBADCRC)
Expand Down Expand Up @@ -691,15 +697,22 @@ static void
xfs_sb_write_verify(
struct xfs_buf *bp)
{
struct xfs_sb sb;
struct xfs_mount *mp = bp->b_target->bt_mount;
struct xfs_buf_log_item *bip = bp->b_log_item;
int error;

error = xfs_sb_verify(bp, false);
if (error) {
xfs_verifier_error(bp, error, __this_address);
return;
}
/*
* Check all the superblock fields. Don't byteswap the xquota flags
* because _verify_common checks the on-disk values.
*/
__xfs_sb_from_disk(&sb, XFS_BUF_TO_SBP(bp), false);
error = xfs_validate_sb_common(mp, bp, &sb);
if (error)
goto out_error;
error = xfs_validate_sb_write(mp, &sb);
if (error)
goto out_error;

if (!xfs_sb_version_hascrc(&mp->m_sb))
return;
Expand All @@ -708,6 +721,10 @@ xfs_sb_write_verify(
XFS_BUF_TO_SBP(bp)->sb_lsn = cpu_to_be64(bip->bli_item.li_lsn);

xfs_buf_update_cksum(bp, XFS_SB_CRC_OFF);
return;

out_error:
xfs_verifier_error(bp, error, __this_address);
}

const struct xfs_buf_ops xfs_sb_buf_ops = {
Expand Down

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