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authorEric Biggers <ebiggers@google.com>2021-01-15 21:18:17 +0300
committerEric Biggers <ebiggers@google.com>2021-02-08 01:51:14 +0300
commit622699cfe6ec5578f52727002d5717ff3f092e23 (patch)
tree70afcd4d36b8ca0d535043f3e64ec23000bc6bff /Documentation/filesystems/fsverity.rst
parente17fe6579de023725ec22a16965e9099e4a05ac9 (diff)
downloadlinux-622699cfe6ec5578f52727002d5717ff3f092e23.tar.xz
fs-verity: support reading Merkle tree with ioctl
Add support for FS_VERITY_METADATA_TYPE_MERKLE_TREE to FS_IOC_READ_VERITY_METADATA. This allows a userspace server program to retrieve the Merkle tree of a verity file for serving to a client which implements fs-verity compatible verification. See the patch which introduced FS_IOC_READ_VERITY_METADATA for more details. This has been tested using a new xfstest which calls this ioctl via a new subcommand for the 'fsverity' program from fsverity-utils. Link: https://lore.kernel.org/r/20210115181819.34732-5-ebiggers@kernel.org Reviewed-by: Victor Hsieh <victorhsieh@google.com> Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org> Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Eric Biggers <ebiggers@google.com>
Diffstat (limited to 'Documentation/filesystems/fsverity.rst')
-rw-r--r--Documentation/filesystems/fsverity.rst10
1 files changed, 9 insertions, 1 deletions
diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst
index 9ef7a7de6008..50b47a6d9ea1 100644
--- a/Documentation/filesystems/fsverity.rst
+++ b/Documentation/filesystems/fsverity.rst
@@ -234,6 +234,8 @@ need this ioctl.
This ioctl takes in a pointer to the following structure::
+ #define FS_VERITY_METADATA_TYPE_MERKLE_TREE 1
+
struct fsverity_read_metadata_arg {
__u64 metadata_type;
__u64 offset;
@@ -242,7 +244,13 @@ This ioctl takes in a pointer to the following structure::
__u64 __reserved;
};
-``metadata_type`` specifies the type of metadata to read.
+``metadata_type`` specifies the type of metadata to read:
+
+- ``FS_VERITY_METADATA_TYPE_MERKLE_TREE`` reads the blocks of the
+ Merkle tree. The blocks are returned in order from the root level
+ to the leaf level. Within each level, the blocks are returned in
+ the same order that their hashes are themselves hashed.
+ See `Merkle tree`_ for more information.
The semantics are similar to those of ``pread()``. ``offset``
specifies the offset in bytes into the metadata item to read from, and