On Thu, Jun 06, 2019 at 08:51:59AM -0700, Eric Biggers wrote:
> From: Eric Biggers <[email protected]>
>
> Add a function for filesystems to call to implement the
> FS_IOC_ENABLE_VERITY ioctl. This ioctl enables fs-verity on a file.
>
> See the "FS_IOC_ENABLE_VERITY" section of
> Documentation/filesystems/fsverity.rst for the documentation.
>
> Signed-off-by: Eric Biggers <[email protected]>
> diff --git a/fs/verity/enable.c b/fs/verity/enable.c
> new file mode 100644
> index 000000000000..7e7ef9d3c376
> --- /dev/null
> +++ b/fs/verity/enable.c
> + /* Tell the filesystem to finish enabling verity on the file */
> + err = vops->end_enable_verity(filp, desc, desc_size, params.tree_size);
> + if (err) {
> + fsverity_err(inode, "%ps() failed with err %d",
> + vops->end_enable_verity, err);
> + fsverity_free_info(vi);
> + } else {
> + /* Successfully enabled verity */
> +
> + WARN_ON(!IS_VERITY(inode));
> +
> + /*
> + * Readers can start using ->i_verity_info immediately, so it
> + * can't be rolled back once set. So don't set it until just
> + * after the filesystem has successfully enabled verity.
> + */
> + fsverity_set_info(inode, vi);
> + }
If end_enable_Verity() retuns success, and IS_VERITY is not set, I
would think that we should report the error via fsverity_err() and
return an error to userspace, and *not* call fsverity_set_info(). I
don't think the stack trace printed by WARN_ON is going to very
interesting, since the call path which gets us to enable_verity() is
not going to be surprising.
> +
> + if (inode->i_size <= 0) {
> + err = -EINVAL;
> + goto out_unlock;
> + }
How hard would it be to support fsverity for zero-length files? There
would be no Merkle tree, but there still would be an fsverity header
file on which we can calculate a checksum for the digital signature.
- Ted
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