From 98dc08bae6780bb950b5c0cdefeb662b22482655 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Mon, 28 Nov 2022 23:04:01 -0800
Subject: [PATCH 1/2] fsverity: stop using PG_error to track error status
As a step towards freeing the PG_error flag for other uses, change ext4
and f2fs to stop using PG_error to track verity errors. Instead, if a
verity error occurs, just mark the whole bio as failed. The coarser
granularity isn't really a problem since it isn't any worse than what
the block layer provides, and errors from a multi-page readahead aren't
reported to applications unless a single-page read fails too.
f2fs supports compression, which makes the f2fs changes a bit more
complicated than desired, but the basic premise still works.
Note: there are still a few uses of PageError in f2fs, but they are on
the write path, so they are unrelated and this patch doesn't touch them.
Reviewed-by: Chao Yu <chao@kernel.org>
Acked-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20221129070401.156114-1-ebiggers@kernel.org
---
fs/ext4/readpage.c | 8 ++----
fs/f2fs/compress.c | 64 ++++++++++++++++++++++------------------------
fs/f2fs/data.c | 53 +++++++++++++++++++++++---------------
fs/verity/verify.c | 12 ++++-----
4 files changed, 72 insertions(+), 65 deletions(-)
diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
index 3d21eae267fca..e604ea4e102b7 100644
--- a/fs/ext4/readpage.c
+++ b/fs/ext4/readpage.c
@@ -75,14 +75,10 @@ static void __read_end_io(struct bio *bio)
bio_for_each_segment_all(bv, bio, iter_all) {
page = bv->bv_page;
- /* PG_error was set if verity failed. */
- if (bio->bi_status || PageError(page)) {
+ if (bio->bi_status)
ClearPageUptodate(page);
- /* will re-read again later */
- ClearPageError(page);
- } else {
+ else
SetPageUptodate(page);
- }
unlock_page(page);
}
if (bio->bi_private)
diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index d315c2de136f2..2b7a5cc4ed662 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -1711,50 +1711,27 @@ static void f2fs_put_dic(struct decompress_io_ctx *dic, bool in_task)
}
}
-/*
- * Update and unlock the cluster's pagecache pages, and release the reference to
- * the decompress_io_ctx that was being held for I/O completion.
- */
-static void __f2fs_decompress_end_io(struct decompress_io_ctx *dic, bool failed,
- bool in_task)
+static void f2fs_verify_cluster(struct work_struct *work)
{
+ struct decompress_io_ctx *dic =
+ container_of(work, struct decompress_io_ctx, verity_work);
int i;
+ /* Verify, update, and unlock the decompressed pages. */
for (i = 0; i < dic->cluster_size; i++) {
struct page *rpage = dic->rpages[i];
if (!rpage)
continue;
- /* PG_error was set if verity failed. */
- if (failed || PageError(rpage)) {
- ClearPageUptodate(rpage);
- /* will re-read again later */
- ClearPageError(rpage);
- } else {
+ if (fsverity_verify_page(rpage))
SetPageUptodate(rpage);
- }
+ else
+ ClearPageUptodate(rpage);
unlock_page(rpage);
}
- f2fs_put_dic(dic, in_task);
-}
-
-static void f2fs_verify_cluster(struct work_struct *work)
-{
- struct decompress_io_ctx *dic =
- container_of(work, struct decompress_io_ctx, verity_work);
- int i;
-
- /* Verify the cluster's decompressed pages with fs-verity. */
- for (i = 0; i < dic->cluster_size; i++) {
- struct page *rpage = dic->rpages[i];
-
- if (rpage && !fsverity_verify_page(rpage))
- SetPageError(rpage);
- }
-
- __f2fs_decompress_end_io(dic, false, true);
+ f2fs_put_dic(dic, true);
}
/*
@@ -1764,6 +1741,8 @@ static void f2fs_verify_cluster(struct work_struct *work)
void f2fs_decompress_end_io(struct decompress_io_ctx *dic, bool failed,
bool in_task)
{
+ int i;
+
if (!failed && dic->need_verity) {
/*
* Note that to avoid deadlocks, the verity work can't be done
@@ -1773,9 +1752,28 @@ void f2fs_decompress_end_io(struct decompress_io_ctx *dic, bool failed,
*/
INIT_WORK(&dic->verity_work, f2fs_verify_cluster);
fsverity_enqueue_verify_work(&dic->verity_work);
- } else {
- __f2fs_decompress_end_io(dic, failed, in_task);
+ return;
+ }
+
+ /* Update and unlock the cluster's pagecache pages. */
+ for (i = 0; i < dic->cluster_size; i++) {
+ struct page *rpage = dic->rpages[i];
+
+ if (!rpage)
+ continue;
+
+ if (failed)
+ ClearPageUptodate(rpage);
+ else
+ SetPageUptodate(rpage);
+ unlock_page(rpage);
}
+
+ /*
+ * Release the reference to the decompress_io_ctx that was being held
+ * for I/O completion.
+ */
+ f2fs_put_dic(dic, in_task);
}
/*
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index a71e818cd67b4..7af75041bd81b 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -116,43 +116,56 @@ struct bio_post_read_ctx {
struct f2fs_sb_info *sbi;
struct work_struct work;
unsigned int enabled_steps;
+ /*
+ * decompression_attempted keeps track of whether
+ * f2fs_end_read_compressed_page() has been called on the pages in the
+ * bio that belong to a compressed cluster yet.
+ */
+ bool decompression_attempted;
block_t fs_blkaddr;
};
+/*
+ * Update and unlock a bio's pages, and free the bio.
+ *
+ * This marks pages up-to-date only if there was no error in the bio (I/O error,
+ * decryption error, or verity error), as indicated by bio->bi_status.
+ *
+ * "Compressed pages" (pagecache pages backed by a compressed cluster on-disk)
+ * aren't marked up-to-date here, as decompression is done on a per-compression-
+ * cluster basis rather than a per-bio basis. Instead, we only must do two
+ * things for each compressed page here: call f2fs_end_read_compressed_page()
+ * with failed=true if an error occurred before it would have normally gotten
+ * called (i.e., I/O error or decryption error, but *not* verity error), and
+ * release the bio's reference to the decompress_io_ctx of the page's cluster.
+ */
static void f2fs_finish_read_bio(struct bio *bio, bool in_task)
{
struct bio_vec *bv;
struct bvec_iter_all iter_all;
+ struct bio_post_read_ctx *ctx = bio->bi_private;
- /*
- * Update and unlock the bio's pagecache pages, and put the
- * decompression context for any compressed pages.
- */
bio_for_each_segment_all(bv, bio, iter_all) {
struct page *page = bv->bv_page;
if (f2fs_is_compressed_page(page)) {
- if (bio->bi_status)
+ if (ctx && !ctx->decompression_attempted)
f2fs_end_read_compressed_page(page, true, 0,
in_task);
f2fs_put_page_dic(page, in_task);
continue;
}
- /* PG_error was set if verity failed. */
- if (bio->bi_status || PageError(page)) {
+ if (bio->bi_status)
ClearPageUptodate(page);
- /* will re-read again later */
- ClearPageError(page);
- } else {
+ else
SetPageUptodate(page);
- }
dec_page_count(F2FS_P_SB(page), __read_io_type(page));
unlock_page(page);
}
- if (bio->bi_private)
- mempool_free(bio->bi_private, bio_post_read_ctx_pool);
+ if (ctx)
+ mempool_free(ctx, bio_post_read_ctx_pool);
bio_put(bio);
}
@@ -185,8 +198,10 @@ static void f2fs_verify_bio(struct work_struct *work)
struct page *page = bv->bv_page;
if (!f2fs_is_compressed_page(page) &&
- !fsverity_verify_page(page))
- SetPageError(page);
+ !fsverity_verify_page(page)) {
+ bio->bi_status = BLK_STS_IOERR;
+ break;
+ }
}
} else {
fsverity_verify_bio(bio);
@@ -245,6 +260,8 @@ static void f2fs_handle_step_decompress(struct bio_post_read_ctx *ctx,
blkaddr++;
}
+ ctx->decompression_attempted = true;
+
/*
* Optimization: if all the bio's pages are compressed, then scheduling
* the per-bio verity work is unnecessary, as verity will be fully
@@ -1062,6 +1079,7 @@ static struct bio *f2fs_grab_read_bio(struct inode *inode, block_t blkaddr,
ctx->sbi = sbi;
ctx->enabled_steps = post_read_steps;
ctx->fs_blkaddr = blkaddr;
+ ctx->decompression_attempted = false;
bio->bi_private = ctx;
}
iostat_alloc_and_bind_ctx(sbi, bio, ctx);
@@ -1089,7 +1107,6 @@ static int f2fs_submit_page_read(struct inode *inode, struct page *page,
bio_put(bio);
return -EFAULT;
}
- ClearPageError(page);
inc_page_count(sbi, F2FS_RD_DATA);
f2fs_update_iostat(sbi, NULL, FS_DATA_READ_IO, F2FS_BLKSIZE);
__submit_bio(sbi, bio, DATA);
@@ -2141,7 +2158,6 @@ static int f2fs_read_single_page(struct inode *inode, struct page *page,
inc_page_count(F2FS_I_SB(inode), F2FS_RD_DATA);
f2fs_update_iostat(F2FS_I_SB(inode), NULL, FS_DATA_READ_IO,
F2FS_BLKSIZE);
- ClearPageError(page);
*last_block_in_bio = block_nr;
goto out;
out:
@@ -2289,7 +2305,6 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
inc_page_count(sbi, F2FS_RD_DATA);
f2fs_update_iostat(sbi, inode, FS_DATA_READ_IO, F2FS_BLKSIZE);
- ClearPageError(page);
*last_block_in_bio = blkaddr;
}
@@ -2306,7 +2321,6 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
for (i = 0; i < cc->cluster_size; i++) {
if (cc->rpages[i]) {
ClearPageUptodate(cc->rpages[i]);
- ClearPageError(cc->rpages[i]);
unlock_page(cc->rpages[i]);
}
}
@@ -2403,7 +2417,6 @@ static int f2fs_mpage_readpages(struct inode *inode,
#ifdef CONFIG_F2FS_FS_COMPRESSION
set_error_page:
#endif
- SetPageError(page);
zero_user_segment(page, 0, PAGE_SIZE);
unlock_page(page);
}
diff --git a/fs/verity/verify.c b/fs/verity/verify.c
index bde8c9b7d25f6..961ba248021f9 100644
--- a/fs/verity/verify.c
+++ b/fs/verity/verify.c
@@ -200,9 +200,8 @@ EXPORT_SYMBOL_GPL(fsverity_verify_page);
* @bio: the bio to verify
*
* Verify a set of pages that have just been read from a verity file. The pages
- * must be pagecache pages that are still locked and not yet uptodate. Pages
- * that fail verification are set to the Error state. Verification is skipped
- * for pages already in the Error state, e.g. due to fscrypt decryption failure.
+ * must be pagecache pages that are still locked and not yet uptodate. If a
+ * page fails verification, then bio->bi_status is set to an error status.
*
* This is a helper function for use by the ->readahead() method of filesystems
* that issue bios to read data directly into the page cache. Filesystems that
@@ -244,9 +243,10 @@ void fsverity_verify_bio(struct bio *bio)
unsigned long level0_ra_pages =
min(max_ra_pages, params->level0_blocks - level0_index);
- if (!PageError(page) &&
- !verify_page(inode, vi, req, page, level0_ra_pages))
- SetPageError(page);
+ if (!verify_page(inode, vi, req, page, level0_ra_pages)) {
+ bio->bi_status = BLK_STS_IOERR;
+ break;
+ }
}
fsverity_free_hash_request(params->hash_alg, req);
From a4bbf53d88c728da9ff6c316b1e4ded63a8f3940 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Mon, 28 Nov 2022 20:51:39 -0800
Subject: [PATCH 2/2] fsverity: simplify fsverity_get_digest()
Instead of looking up the algorithm by name in hash_algo_name[] to get
its hash_algo ID, just store the hash_algo ID in the fsverity_hash_alg
struct. Verify at boot time that every fsverity_hash_alg has a valid
hash_algo ID with matching digest size.
Remove an unnecessary memset() of the whole digest array to 0 before the
digest is copied into it.
Finally, remove the pr_debug statement. There is already a pr_debug for
the fsverity digest when the file is opened.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Link: https://lore.kernel.org/r/20221129045139.69803-1-ebiggers@kernel.org
---
fs/verity/fsverity_private.h | 5 +++++
fs/verity/hash_algs.c | 6 ++++++
fs/verity/measure.c | 19 ++-----------------
3 files changed, 13 insertions(+), 17 deletions(-)
diff --git a/fs/verity/fsverity_private.h b/fs/verity/fsverity_private.h
index dbe1ce5b450a8..c7fcb855e0682 100644
--- a/fs/verity/fsverity_private.h
+++ b/fs/verity/fsverity_private.h
@@ -32,6 +32,11 @@ struct fsverity_hash_alg {
unsigned int digest_size; /* digest size in bytes, e.g. 32 for SHA-256 */
unsigned int block_size; /* block size in bytes, e.g. 64 for SHA-256 */
mempool_t req_pool; /* mempool with a preallocated hash request */
+ /*
+ * The HASH_ALGO_* constant for this algorithm. This is different from
+ * FS_VERITY_HASH_ALG_*, which uses a different numbering scheme.
+ */
+ enum hash_algo algo_id;
};
/* Merkle tree parameters: hash algorithm, initial hash state, and topology */
diff --git a/fs/verity/hash_algs.c b/fs/verity/hash_algs.c
index 71d0fccb6d4c4..6f8170cf4ae71 100644
--- a/fs/verity/hash_algs.c
+++ b/fs/verity/hash_algs.c
@@ -16,11 +16,13 @@ struct fsverity_hash_alg fsverity_hash_algs[] = {
.name = "sha256",
.digest_size = SHA256_DIGEST_SIZE,
.block_size = SHA256_BLOCK_SIZE,
+ .algo_id = HASH_ALGO_SHA256,
},
[FS_VERITY_HASH_ALG_SHA512] = {
.name = "sha512",
.digest_size = SHA512_DIGEST_SIZE,
.block_size = SHA512_BLOCK_SIZE,
+ .algo_id = HASH_ALGO_SHA512,
},
};
@@ -324,5 +326,9 @@ void __init fsverity_check_hash_algs(void)
*/
BUG_ON(!is_power_of_2(alg->digest_size));
BUG_ON(!is_power_of_2(alg->block_size));
+
+ /* Verify that there is a valid mapping to HASH_ALGO_*. */
+ BUG_ON(alg->algo_id == 0);
+ BUG_ON(alg->digest_size != hash_digest_size[alg->algo_id]);
}
}
diff --git a/fs/verity/measure.c b/fs/verity/measure.c
index e99c00350c28d..5c79ea1b24687 100644
--- a/fs/verity/measure.c
+++ b/fs/verity/measure.c
@@ -65,8 +65,7 @@ EXPORT_SYMBOL_GPL(fsverity_ioctl_measure);
* @alg: (out) pointer to the hash algorithm enumeration
*
* Return the file hash algorithm and digest of an fsverity protected file.
- * Assumption: before calling fsverity_get_digest(), the file must have been
- * opened.
+ * Assumption: before calling this, the file must have been opened.
*
* Return: 0 on success, -errno on failure
*/
@@ -76,27 +75,13 @@ int fsverity_get_digest(struct inode *inode,
{
const struct fsverity_info *vi;
const struct fsverity_hash_alg *hash_alg;
- int i;
vi = fsverity_get_info(inode);
if (!vi)
return -ENODATA; /* not a verity file */
hash_alg = vi->tree_params.hash_alg;
- memset(digest, 0, FS_VERITY_MAX_DIGEST_SIZE);
-
- /* convert the verity hash algorithm name to a hash_algo_name enum */
- i = match_string(hash_algo_name, HASH_ALGO__LAST, hash_alg->name);
- if (i < 0)
- return -EINVAL;
- *alg = i;
-
- if (WARN_ON_ONCE(hash_alg->digest_size != hash_digest_size[*alg]))
- return -EINVAL;
memcpy(digest, vi->file_digest, hash_alg->digest_size);
-
- pr_debug("file digest %s:%*phN\n", hash_algo_name[*alg],
- hash_digest_size[*alg], digest);
-
+ *alg = hash_alg->algo_id;
return 0;
}