[PATCH 17/40] fsverity: report validation errors back to the filesystem

["Darrick J. Wong" <djwong@kernel.org>]

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       |   14 +++++++++++++-
 include/linux/fsverity.h |   11 +++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)


diff --git a/fs/verity/verify.c b/fs/verity/verify.c
index 494225f60608..0782e94bc818 100644
--- a/fs/verity/verify.c
+++ b/fs/verity/verify.c
@@ -255,6 +255,15 @@ verify_data_block(struct inode *inode, struct fsverity_info *vi,
 	return false;
 }
 
+static void fsverity_fail_validation(struct inode *inode, loff_t pos,
+				     size_t len)
+{
+	const struct fsverity_operations *vops = inode->i_sb->s_vop;
+
+	if (vops->fail_validation)
+		vops->fail_validation(inode, pos, len);
+}
+
 static bool
 verify_data_blocks(struct folio *data_folio, size_t len, size_t offset,
 		   unsigned long max_ra_bytes)
@@ -277,8 +286,11 @@ verify_data_blocks(struct folio *data_folio, size_t len, size_t offset,
 		valid = verify_data_block(inode, vi, data, pos + offset,
 					  max_ra_bytes);
 		kunmap_local(data);
-		if (!valid)
+		if (!valid) {
+			fsverity_fail_validation(inode, pos + offset,
+						 block_size);
 			return false;
+		}
 		offset += block_size;
 		len -= block_size;
 	} while (len);
diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h
index da23f1e30151..57df509295f4 100644
--- a/include/linux/fsverity.h
+++ b/include/linux/fsverity.h
@@ -236,6 +236,17 @@ struct fsverity_operations {
 	 * be implemented.
 	 */
 	void (*drop_merkle_tree_block)(struct fsverity_blockbuf *block);
+
+	/**
+	 * Notify the filesystem that file data validation failed
+	 *
+	 * @inode: the inode being validated
+	 * @pos: the file position of the invalid data
+	 * @len: the length of the invalid data
+	 *
+	 * This is called when fs-verity cannot validate the file contents.
+	 */
+	void (*fail_validation)(struct inode *inode, loff_t pos, size_t len);
 };
 
 #ifdef CONFIG_FS_VERITY