Re: [PATCH v4 10/16] fs-verity: implement FS_IOC_ENABLE_VERITY ioctl
From: "Theodore Ts'o" <tytso@mit.edu>
Date: 2019-06-15 15:08:48
Also in:
linux-ext4, linux-f2fs-devel, linux-fscrypt, linux-fsdevel, linux-integrity
On Thu, Jun 06, 2019 at 08:51:59AM -0700, Eric Biggers wrote:
From: Eric Biggers <redacted> 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 <redacted>
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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.
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+ + 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