[05/24] fsverity: expose merkle tree geometry to callers

Commit Message

Andrey Albershteyn Dec. 29, 2024, 1:39 p.m. UTC

From: "Darrick J. Wong" <[e-mail]>

Create a function that will return selected information about the
geometry of the merkle tree.  Online fsck for XFS will need this piece
to perform basic checks of the merkle tree.

Signed-off-by: Darrick J. Wong <[e-mail]>
---
 fs/verity/open.c         | 37 +++++++++++++++++++++++++++++++++++++
 include/linux/fsverity.h | 11 +++++++++++
 2 files changed, 48 insertions(+)

Patch

diff --git a/fs/verity/open.c b/fs/verity/open.c
index fdeb95eca3af..de1d0bd6e703 100644
--- a/fs/verity/open.c
+++ b/fs/verity/open.c
@@ -407,6 +407,43 @@  void __fsverity_cleanup_inode(struct inode *inode)
 }
 EXPORT_SYMBOL_GPL(__fsverity_cleanup_inode);
 
+/**
+ * fsverity_merkle_tree_geometry() - return Merkle tree geometry
+ * @inode: the inode to query
+ * @block_size: will be set to the log2 of the size of a merkle tree block
+ * @block_size: will be set to the size of a merkle tree block, in bytes
+ * @tree_size: will be set to the size of the merkle tree, in bytes
+ *
+ * Callers are not required to have opened the file.
+ *
+ * Return: 0 for success, -ENODATA if verity is not enabled, or any of the
+ * error codes that can result from loading verity information while opening a
+ * file.
+ */
+int fsverity_merkle_tree_geometry(struct inode *inode, u8 *log_blocksize,
+				  unsigned int *block_size, u64 *tree_size)
+{
+	struct fsverity_info *vi;
+	int error;
+
+	if (!IS_VERITY(inode))
+		return -ENODATA;
+
+	error = ensure_verity_info(inode);
+	if (error)
+		return error;
+
+	vi = inode->i_verity_info;
+	if (log_blocksize)
+		*log_blocksize = vi->tree_params.log_blocksize;
+	if (block_size)
+		*block_size = vi->tree_params.block_size;
+	if (tree_size)
+		*tree_size = vi->tree_params.tree_size;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fsverity_merkle_tree_geometry);
+
 void __init fsverity_init_info_cache(void)
 {
 	fsverity_info_cachep = KMEM_CACHE_USERCOPY(
diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h
index 81b07909d783..8627b11082b0 100644
--- a/include/linux/fsverity.h
+++ b/include/linux/fsverity.h
@@ -157,6 +157,9 @@  int __fsverity_file_open(struct inode *inode, struct file *filp);
 int __fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr);
 void __fsverity_cleanup_inode(struct inode *inode);
 
+int fsverity_merkle_tree_geometry(struct inode *inode, u8 *log_blocksize,
+				  unsigned int *block_size, u64 *tree_size);
+
 /**
  * fsverity_cleanup_inode() - free the inode's verity info, if present
  * @inode: an inode being evicted
@@ -229,6 +232,14 @@  static inline void fsverity_cleanup_inode(struct inode *inode)
 {
 }
 
+static inline int fsverity_merkle_tree_geometry(struct inode *inode,
+						u8 *log_blocksize,
+						unsigned int *block_size,
+						u64 *tree_size)
+{
+	return -EOPNOTSUPP;
+}
+
 /* read_metadata.c */
 
 static inline int fsverity_ioctl_read_metadata(struct file *filp,