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author | Eric Biggers <ebiggers@google.com> | 2021-01-15 10:18:19 -0800 |
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committer | Eric Biggers <ebiggers@google.com> | 2021-02-07 14:51:19 -0800 |
commit | 07c99001312cbf90a357d4877a358f796eede65b (patch) | |
tree | 12c2787f495d8fdbf605e1fa1bbd835aa204458a /fs/verity/read_metadata.c | |
parent | 947191ac8caba85e25e0e036b0f097fee9e817f3 (diff) | |
download | linux-07c99001312cbf90a357d4877a358f796eede65b.tar.gz linux-07c99001312cbf90a357d4877a358f796eede65b.tar.bz2 linux-07c99001312cbf90a357d4877a358f796eede65b.zip |
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 'fs/verity/read_metadata.c')
-rw-r--r-- | fs/verity/read_metadata.c | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/fs/verity/read_metadata.c b/fs/verity/read_metadata.c index 2dea6dd3bb05..7e2d0c7bdf0d 100644 --- a/fs/verity/read_metadata.c +++ b/fs/verity/read_metadata.c @@ -114,6 +114,34 @@ static int fsverity_read_descriptor(struct inode *inode, kfree(desc); return res; } + +static int fsverity_read_signature(struct inode *inode, + void __user *buf, u64 offset, int length) +{ + struct fsverity_descriptor *desc; + size_t desc_size; + int res; + + res = fsverity_get_descriptor(inode, &desc, &desc_size); + if (res) + return res; + + if (desc->sig_size == 0) { + res = -ENODATA; + goto out; + } + + /* + * Include only the signature. Note that fsverity_get_descriptor() + * already verified that sig_size is in-bounds. + */ + res = fsverity_read_buffer(buf, offset, length, desc->signature, + le32_to_cpu(desc->sig_size)); +out: + kfree(desc); + return res; +} + /** * fsverity_ioctl_read_metadata() - read verity metadata from a file * @filp: file to read the metadata from @@ -158,6 +186,8 @@ int fsverity_ioctl_read_metadata(struct file *filp, const void __user *uarg) length); case FS_VERITY_METADATA_TYPE_DESCRIPTOR: return fsverity_read_descriptor(inode, buf, arg.offset, length); + case FS_VERITY_METADATA_TYPE_SIGNATURE: + return fsverity_read_signature(inode, buf, arg.offset, length); default: return -EINVAL; } |