[PATCH 6.6 149/299] dm-integrity: recheck the integrity tag after a failure

Greg Kroah-Hartman
2024-02-27T13:53:39Z

From: Mikulas Patocka <mpatocka@redhat.com>

commit c88f5e553fe38b2ffc4c33d08654e5281b297677 upstream.

If a userspace process reads (with O_DIRECT) multiple blocks into the same
buffer, dm-integrity reports an error [1]. The error is reported in a log
and it may cause RAID leg being kicked out of the array.

This commit fixes dm-integrity, so that if integrity verification fails,
the data is read again into a kernel buffer (where userspace can't modify
it) and the integrity tag is rechecked. If the recheck succeeds, the
content of the kernel buffer is copied into the user buffer; if the
recheck fails, an integrity error is reported.

[1] https://people.redhat.com/~mpatocka/testcases/blk-auth-modify/read2.c

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/md/dm-integrity.c | 93 +++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 84 insertions(+), 9 deletions(-)

--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -278,6 +278,8 @@ struct dm_integrity_c {

atomic64_t number_of_mismatches;

+ mempool_t recheck_pool;
+
struct notifier_block reboot_notifier;
};

@@ -1699,6 +1701,79 @@ failed:
get_random_bytes(result, ic->tag_size);
}

+static void integrity_recheck(struct dm_integrity_io *dio)
+{
+ struct bio *bio = dm_bio_from_per_bio_data(dio, sizeof(struct dm_integrity_io));
+ struct dm_integrity_c *ic = dio->ic;
+ struct bvec_iter iter;
+ struct bio_vec bv;
+ sector_t sector, logical_sector, area, offset;
+ char checksum_onstack[max_t(size_t, HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)];
+ struct page *page;
+ void *buffer;
+
+ get_area_and_offset(ic, dio->range.logical_sector, &area, &offset);
+ dio->metadata_block = get_metadata_sector_and_offset(ic, area, offset,
+ &dio->metadata_offset);
+ sector = get_data_sector(ic, area, offset);
+ logical_sector = dio->range.logical_sector;
+
+ page = mempool_alloc(&ic->recheck_pool, GFP_NOIO);
+ buffer = page_to_virt(page);
+
+ __bio_for_each_segment(bv, bio, iter, dio->bio_details.bi_iter) {
+ unsigned pos = 0;
+
+ do {
+ char *mem;
+ int r;
+ struct dm_io_request io_req;
+ struct dm_io_region io_loc;
+ io_req.bi_opf = REQ_OP_READ;
+ io_req.mem.type = DM_IO_KMEM;
+ io_req.mem.ptr.addr = buffer;
+ io_req.notify.fn = NULL;
+ io_req.client = ic->io;
+ io_loc.bdev = ic->dev->bdev;
+ io_loc.sector = sector;
+ io_loc.count = ic->sectors_per_block;
+
+ r = dm_io(&io_req, 1, &io_loc, NULL);
+ if (unlikely(r)) {
+ dio->bi_status = errno_to_blk_status(r);
+ goto free_ret;
+ }
+
+ integrity_sector_checksum(ic, logical_sector, buffer,
+ checksum_onstack);
+ r = dm_integrity_rw_tag(ic, checksum_onstack, &dio->metadata_block,
+ &dio->metadata_offset, ic->tag_size, TAG_CMP);
+ if (r) {
+ if (r > 0) {
+ DMERR_LIMIT("%pg: Checksum failed at sector 0x%llx",
+ bio->bi_bdev, logical_sector);
+ atomic64_inc(&ic->number_of_mismatches);
+ dm_audit_log_bio(DM_MSG_PREFIX, "integrity-checksum",
+ bio, logical_sector, 0);
+ r = -EILSEQ;
+ }
+ dio->bi_status = errno_to_blk_status(r);
+ goto free_ret;
+ }
+
+ mem = bvec_kmap_local(&bv);
+ memcpy(mem + pos, buffer, ic->sectors_per_block << SECTOR_SHIFT);
+ kunmap_local(mem);
+
+ pos += ic->sectors_per_block << SECTOR_SHIFT;
+ sector += ic->sectors_per_block;
+ logical_sector += ic->sectors_per_block;
+ } while (pos < bv.bv_len);
+ }
+free_ret:
+ mempool_free(page, &ic->recheck_pool);
+}
+
static void integrity_metadata(struct work_struct *w)
{
struct dm_integrity_io *dio = container_of(w, struct dm_integrity_io, work);
@@ -1786,15 +1861,8 @@ again:
checksums_ptr - checksums, dio->op == REQ_OP_READ ? TAG_CMP : TAG_WRITE);
if (unlikely(r)) {
if (r > 0) {
- sector_t s;
-
- s = sector - ((r + ic->tag_size - 1) / ic->tag_size);
- DMERR_LIMIT("%pg: Checksum failed at sector 0x%llx",
- bio->bi_bdev, s);
- r = -EILSEQ;
- atomic64_inc(&ic->number_of_mismatches);
- dm_audit_log_bio(DM_MSG_PREFIX, "integrity-checksum",
- bio, s, 0);
+ integrity_recheck(dio);
+ goto skip_io;
}
if (likely(checksums != checksums_onstack))
kfree(checksums);
@@ -4271,6 +4339,12 @@ static int dm_integrity_ctr(struct dm_ta
goto bad;
}

+ r = mempool_init_page_pool(&ic->recheck_pool, 1, 0);
+ if (r) {
+ ti->error = "Cannot allocate mempool";
+ goto bad;
+ }
+
ic->metadata_wq = alloc_workqueue("dm-integrity-metadata",
WQ_MEM_RECLAIM, METADATA_WORKQUEUE_MAX_ACTIVE);
if (!ic->metadata_wq) {
@@ -4619,6 +4693,7 @@ static void dm_integrity_dtr(struct dm_t
kvfree(ic->bbs);
if (ic->bufio)
dm_bufio_client_destroy(ic->bufio);
+ mempool_exit(&ic->recheck_pool);
mempool_exit(&ic->journal_io_mempool);
if (ic->io)
dm_io_client_destroy(ic->io);