Re: [PATCH 11/13] fsverity: report validation errors back to the filesystem

Darrick J. Wong
2024-04-24T19:03:30Z

On Wed, Apr 24, 2024 at 06:52:30PM +0000, Eric Biggers wrote:
> On Wed, Apr 24, 2024 at 11:18:26AM -0700, Darrick J. Wong wrote:
> > On Thu, Apr 04, 2024 at 11:09:11PM -0400, Eric Biggers wrote:
> > > On Fri, Mar 29, 2024 at 05:35:32PM -0700, Darrick J. Wong wrote:
> > > > + /**
> > > > + * Notify the filesystem that file data validation failed
> > > > + *
> > > > + * @inode: the inode being validated
> > > > + * @pos: the file position of the invalid data
> > > > + * @len: the length of the invalid data
> > > > + *
> > > > + * This is called when fs-verity cannot validate the file contents.
> > > > + */
> > > > + void (*fail_validation)(struct inode *inode, loff_t pos, size_t len);
> > >
> > > There is a difference between the file actually being corrupt (mismatching
> > > hashes) and other problems like disk errors reading from the Merkle tree.
> > > "Validation failed" is a bit ambiguous, and "cannot validate the file contents"
> > > even more so. Do you want only file corruption errors? If so it may be a good
> > > idea to call this 'file_corrupt', which would be consistent with the
> > > "FILE CORRUPTED" error message in fs/verity/verify.c. Or do you actually want
> > > all errors? Either way, it needs to be clarified what is actually meant.
> >
> > I only want actual file corruption errors -- XFS can handle disk errors
> > from reading merkle tree blocks on its own. I'll change this to
> > file_corrupt. How's this?
> >
> > /**
> > * Notify the filesystem that file data is corrupt.
> > *
> > * @inode: the inode being validated
> > * @pos: the file position of the invalid data
> > * @len: the length of the invalid data
> > *
> > * This function is called when fs-verity cannot validate the file
> > * contents against the merkle tree hashes and logs a FILE CORRUPTED
> > * error message.
> > */
> > void (*file_corrupt)(struct inode *inode, loff_t pos, size_t len);
>
> It looks good except for the last sentence, which still has the potentially
> misleading "cannot validate the file contents" wording. How about something
> like the following:
>
> "This function is called when fs-verity detects that a portion of a file's data
> is inconsistent with the Merkle tree, or a Merkle tree block needed to validate
> the data is inconsistent with the level above it."

Much better! I'll change it to that, thank you for the suggestion.

--D

> - Eric
>