[PATCH RFC 06/29] fsverity: report validation errors back to the filesystem

[Andrey Albershteyn <aalbersh@redhat.com>]

From: "Darrick J. Wong" <djwong@kernel.org>

Provide a new function call so that validation errors can be reported
back to the filesystem.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/verity/verify.c              |  4 ++++
 include/linux/fsverity.h        | 14 ++++++++++++++
 include/trace/events/fsverity.h | 19 +++++++++++++++++++
 3 files changed, 37 insertions(+)

diff --git a/fs/verity/verify.c b/fs/verity/verify.c
index 580486168467..917a5fb5388f 100644
--- a/fs/verity/verify.c
+++ b/fs/verity/verify.c
@@ -243,6 +243,10 @@ verify_data_block(struct inode *inode, struct fsverity_info *vi,
 		     data_pos, level - 1,
 		     params->hash_alg->name, hsize, want_hash,
 		     params->hash_alg->name, hsize, real_hash);
+	trace_fsverity_file_corrupt(inode, data_pos, params->block_size);
+	if (inode->i_sb->s_vop->file_corrupt)
+		inode->i_sb->s_vop->file_corrupt(inode, data_pos,
+						 params->block_size);
 error:
 	for (; level > 0; level--) {
 		kunmap_local(hblocks[level - 1].addr);
diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h
index 9b91bd54fb75..d263e988bec2 100644
--- a/include/linux/fsverity.h
+++ b/include/linux/fsverity.h
@@ -120,6 +120,20 @@ struct fsverity_operations {
 	 */
 	int (*write_merkle_tree_block)(struct inode *inode, const void *buf,
 				       u64 pos, unsigned int size);
+
+	/**
+	 * Notify the filesystem that file data is corrupt.
+	 *
+	 * @inode: the inode being validated
+	 * @pos: the file position of the invalid data
+	 * @len: the length of the invalid data
+	 *
+	 * This function is called when fs-verity detects that a portion of a
+	 * file's data is inconsistent with the Merkle tree, or a Merkle tree
+	 * block needed to validate the data is inconsistent with the level
+	 * above it.
+	 */
+	void (*file_corrupt)(struct inode *inode, loff_t pos, size_t len);
 };
 
 #ifdef CONFIG_FS_VERITY
diff --git a/include/trace/events/fsverity.h b/include/trace/events/fsverity.h
index dab220884b89..375fdddac6a9 100644
--- a/include/trace/events/fsverity.h
+++ b/include/trace/events/fsverity.h
@@ -137,6 +137,25 @@ TRACE_EVENT(fsverity_verify_merkle_block,
 		__entry->hidx)
 );
 
+TRACE_EVENT(fsverity_file_corrupt,
+	TP_PROTO(const struct inode *inode, loff_t pos, size_t len),
+	TP_ARGS(inode, pos, len),
+	TP_STRUCT__entry(
+		__field(ino_t, ino)
+		__field(loff_t, pos)
+		__field(size_t, len)
+	),
+	TP_fast_assign(
+		__entry->ino = inode->i_ino;
+		__entry->pos = pos;
+		__entry->len = len;
+	),
+	TP_printk("ino %lu pos %llu len %zu",
+		(unsigned long) __entry->ino,
+		__entry->pos,
+		__entry->len)
+);
+
 #endif /* _TRACE_FSVERITY_H */
 
 /* This part must be outside protection */

-- 
2.50.0