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| author | Eric Biggers <ebiggers@google.com> | 2021-01-15 10:18:19 -0800 |
|---|---|---|
| committer | Eric Biggers <ebiggers@google.com> | 2021-02-07 14:51:19 -0800 |
| commit | 07c99001312cbf90a357d4877a358f796eede65b (patch) | |
| tree | 12c2787f495d8fdbf605e1fa1bbd835aa204458a /Documentation/filesystems | |
| parent | 947191ac8caba85e25e0e036b0f097fee9e817f3 (diff) | |
| download | linux-07c99001312cbf90a357d4877a358f796eede65b.tar.bz2 | |
fs-verity: support reading signature with ioctl
Add support for FS_VERITY_METADATA_TYPE_SIGNATURE to
FS_IOC_READ_VERITY_METADATA. This allows a userspace server program to
retrieve the built-in signature (if present) 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.
The ability for userspace to read the built-in signatures is also useful
because it allows a system that is using the in-kernel signature
verification to migrate to userspace signature verification.
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/20210115181819.34732-7-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')
| -rw-r--r-- | Documentation/filesystems/fsverity.rst | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst index 6dc5772037ef..1d831e3cbcb3 100644 --- a/Documentation/filesystems/fsverity.rst +++ b/Documentation/filesystems/fsverity.rst @@ -236,6 +236,7 @@ This ioctl takes in a pointer to the following structure:: #define FS_VERITY_METADATA_TYPE_MERKLE_TREE 1 #define FS_VERITY_METADATA_TYPE_DESCRIPTOR 2 + #define FS_VERITY_METADATA_TYPE_SIGNATURE 3 struct fsverity_read_metadata_arg { __u64 metadata_type; @@ -256,6 +257,10 @@ This ioctl takes in a pointer to the following structure:: - ``FS_VERITY_METADATA_TYPE_DESCRIPTOR`` reads the fs-verity descriptor. See `fs-verity descriptor`_. +- ``FS_VERITY_METADATA_TYPE_SIGNATURE`` reads the signature which was + passed to FS_IOC_ENABLE_VERITY, if any. See `Built-in signature + verification`_. + The semantics are similar to those of ``pread()``. ``offset`` specifies the offset in bytes into the metadata item to read from, and ``length`` specifies the maximum number of bytes to read from the @@ -279,7 +284,9 @@ FS_IOC_READ_VERITY_METADATA can fail with the following errors: - ``EINTR``: the ioctl was interrupted before any data was read - ``EINVAL``: reserved fields were set, or ``offset + length`` overflowed -- ``ENODATA``: the file is not a verity file +- ``ENODATA``: the file is not a verity file, or + FS_VERITY_METADATA_TYPE_SIGNATURE was requested but the file doesn't + have a built-in signature - ``ENOTTY``: this type of filesystem does not implement fs-verity, or this ioctl is not yet implemented on it - ``EOPNOTSUPP``: the kernel was not configured with fs-verity |