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xfs: check directory bestfree information in the verifier 

Create a variant of xfs_dir2_data_freefind that is suitable for use in a
verifier.  Because _freefind is called by the verifier, we simply
duplicate the _freefind function, convert the ASSERTs to return
__this_address, and modify the verifier to call our new function.  Once
we've made it impossible for directory blocks with bad bestfree data to
make it into the filesystem we can remove the DEBUG code from the
regular _freefind function.

Underlying argument: corruption of on-disk metadata should return
-EFSCORRUPTED instead of blowing ASSERTs.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
This commit is contained in:
Darrick J. Wong 2018-06-03 16:10:13 -07:00
parent 924cade4df
commit e4f45eff86
1 changed files with 69 additions and 36 deletions
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105
fs/xfs/libxfs/xfs_dir2_data.c
View File

@ -33,6 +33,11 @@
#include "xfs_cksum.h"
#include "xfs_log.h"
static xfs_failaddr_t xfs_dir2_data_freefind_verify(
struct xfs_dir2_data_hdr *hdr, struct xfs_dir2_data_free *bf,
struct xfs_dir2_data_unused *dup,
struct xfs_dir2_data_free **bf_ent);
/*
* Check the consistency of the data block.
* The input can also be a block-format directory.
@ -147,6 +152,8 @@ __xfs_dir3_data_check(
* doesn't need to be there.
*/
if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
xfs_failaddr_t fa;
if (lastfree != 0)
return __this_address;
if (endp < p + be16_to_cpu(dup->length))
@ -154,7 +161,9 @@ __xfs_dir3_data_check(
if (be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)) !=
(char *)dup - (char *)hdr)
return __this_address;
dfp = xfs_dir2_data_freefind(hdr, bf, dup);
fa = xfs_dir2_data_freefind_verify(hdr, bf, dup, &dfp);
if (fa)
return fa;
if (dfp) {
i = (int)(dfp - bf);
if ((freeseen & (1 << i)) != 0)
@ -380,6 +389,65 @@ xfs_dir3_data_readahead(
XFS_DATA_FORK, &xfs_dir3_data_reada_buf_ops);
}
/*
* Find the bestfree entry that exactly coincides with unused directory space
* or a verifier error because the bestfree data are bad.
*/
static xfs_failaddr_t
xfs_dir2_data_freefind_verify(
struct xfs_dir2_data_hdr *hdr,
struct xfs_dir2_data_free *bf,
struct xfs_dir2_data_unused *dup,
struct xfs_dir2_data_free **bf_ent)
{
struct xfs_dir2_data_free *dfp;
xfs_dir2_data_aoff_t off;
bool matched = false;
bool seenzero = false;
*bf_ent = NULL;
off = (xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr);
/*
* Validate some consistency in the bestfree table.
* Check order, non-overlapping entries, and if we find the
* one we're looking for it has to be exact.
*/
for (dfp = &bf[0]; dfp < &bf[XFS_DIR2_DATA_FD_COUNT]; dfp++) {
if (!dfp->offset) {
if (dfp->length)
return __this_address;
seenzero = true;
continue;
}
if (seenzero)
return __this_address;
if (be16_to_cpu(dfp->offset) == off) {
matched = true;
if (dfp->length != dup->length)
return __this_address;
} else if (be16_to_cpu(dfp->offset) > off) {
if (off + be16_to_cpu(dup->length) >
be16_to_cpu(dfp->offset))
return __this_address;
} else {
if (be16_to_cpu(dfp->offset) +
be16_to_cpu(dfp->length) > off)
return __this_address;
}
if (!matched &&
be16_to_cpu(dfp->length) < be16_to_cpu(dup->length))
return __this_address;
if (dfp > &bf[0] &&
be16_to_cpu(dfp[-1].length) < be16_to_cpu(dfp[0].length))
return __this_address;
}
/* Looks ok so far; now try to match up with a bestfree entry. */
*bf_ent = xfs_dir2_data_freefind(hdr, bf, dup);
return NULL;
}
/*
* Given a data block and an unused entry from that block,
* return the bestfree entry if any that corresponds to it.
@ -392,44 +460,9 @@ xfs_dir2_data_freefind(
{
xfs_dir2_data_free_t *dfp; /* bestfree entry */
xfs_dir2_data_aoff_t off; /* offset value needed */
#ifdef DEBUG
int matched; /* matched the value */
int seenzero; /* saw a 0 bestfree entry */
#endif
off = (xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr);
#ifdef DEBUG
/*
* Validate some consistency in the bestfree table.
* Check order, non-overlapping entries, and if we find the
* one we're looking for it has to be exact.
*/
ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
hdr->magic == cpu_to_be32(XFS_DIR3_DATA_MAGIC) ||
hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC) ||
hdr->magic == cpu_to_be32(XFS_DIR3_BLOCK_MAGIC));
for (dfp = &bf[0], seenzero = matched = 0;
dfp < &bf[XFS_DIR2_DATA_FD_COUNT];
dfp++) {
if (!dfp->offset) {
ASSERT(!dfp->length);
seenzero = 1;
continue;
}
ASSERT(seenzero == 0);
if (be16_to_cpu(dfp->offset) == off) {
matched = 1;
ASSERT(dfp->length == dup->length);
} else if (off < be16_to_cpu(dfp->offset))
ASSERT(off + be16_to_cpu(dup->length) <= be16_to_cpu(dfp->offset));
else
ASSERT(be16_to_cpu(dfp->offset) + be16_to_cpu(dfp->length) <= off);
ASSERT(matched || be16_to_cpu(dfp->length) >= be16_to_cpu(dup->length));
if (dfp > &bf[0])
ASSERT(be16_to_cpu(dfp[-1].length) >= be16_to_cpu(dfp[0].length));
}
#endif
/*
* If this is smaller than the smallest bestfree entry,
* it can't be there since they're sorted.