diff mbox series

[RFC,5/7] fs/xfs: support `DISABLE_FS_CSUM_VERIFICATION` config option

Message ID 20221014084837.1787196-6-hrkanabar@gmail.com
State New
Headers
Series fs: Debug config option to disable filesystem checksum verification for fuzzing |

Commit Message

Hrutvik Kanabar Oct. 14, 2022, 8:48 a.m. UTC 
  From: Hrutvik Kanabar <hrutvik@google.com>

When `DISABLE_FS_CSUM_VERIFICATION` is enabled, return truthy value for
`xfs_verify_cksum`, which is the key function implementing checksum
verification for XFS.

Signed-off-by: Hrutvik Kanabar <hrutvik@google.com>
---
 fs/xfs/libxfs/xfs_cksum.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

Darrick J. Wong Oct. 14, 2022, 3:44 p.m. UTC | #1 
On Fri, Oct 14, 2022 at 08:48:35AM +0000, Hrutvik Kanabar wrote:
> From: Hrutvik Kanabar <hrutvik@google.com>
> 
> When `DISABLE_FS_CSUM_VERIFICATION` is enabled, return truthy value for
> `xfs_verify_cksum`, which is the key function implementing checksum
> verification for XFS.
> 
> Signed-off-by: Hrutvik Kanabar <hrutvik@google.com>

NAK, we're not going to break XFS for the sake of automated fuzz tools.

You'll have to adapt your fuzzing tools to rewrite the block header
checksums, like the existing xfs fuzz testing framework does.  See
the xfs_db 'fuzz -d' command and the relevant fstests.

--D

> ---
>  fs/xfs/libxfs/xfs_cksum.h | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_cksum.h b/fs/xfs/libxfs/xfs_cksum.h
> index 999a290cfd72..ba55b1afa382 100644
> --- a/fs/xfs/libxfs/xfs_cksum.h
> +++ b/fs/xfs/libxfs/xfs_cksum.h
> @@ -76,7 +76,10 @@ xfs_verify_cksum(char *buffer, size_t length, unsigned long cksum_offset)
>  {
>  	uint32_t crc = xfs_start_cksum_safe(buffer, length, cksum_offset);
>  
> -	return *(__le32 *)(buffer + cksum_offset) == xfs_end_cksum(crc);
> +	if (IS_ENABLED(CONFIG_DISABLE_FS_CSUM_VERIFICATION))
> +		return 1;
> +	else
> +		return *(__le32 *)(buffer + cksum_offset) == xfs_end_cksum(crc);
>  }
>  
>  #endif /* _XFS_CKSUM_H */
> -- 
> 2.38.0.413.g74048e4d9e-goog
>
Dmitry Vyukov Oct. 17, 2022, 8:32 a.m. UTC | #2 
On Fri, 14 Oct 2022 at 17:44, Darrick J. Wong <djwong@kernel.org> wrote:
>
> On Fri, Oct 14, 2022 at 08:48:35AM +0000, Hrutvik Kanabar wrote:
> > From: Hrutvik Kanabar <hrutvik@google.com>
> >
> > When `DISABLE_FS_CSUM_VERIFICATION` is enabled, return truthy value for
> > `xfs_verify_cksum`, which is the key function implementing checksum
> > verification for XFS.
> >
> > Signed-off-by: Hrutvik Kanabar <hrutvik@google.com>
>
> NAK, we're not going to break XFS for the sake of automated fuzz tools.

Hi Darrick,

What do you mean by "break"? If this config is not enabled the
behavior is not affected as far as I see.

> You'll have to adapt your fuzzing tools to rewrite the block header
> checksums, like the existing xfs fuzz testing framework does.  See
> the xfs_db 'fuzz -d' command and the relevant fstests.
>
> --D
>
> > ---
> >  fs/xfs/libxfs/xfs_cksum.h | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/xfs/libxfs/xfs_cksum.h b/fs/xfs/libxfs/xfs_cksum.h
> > index 999a290cfd72..ba55b1afa382 100644
> > --- a/fs/xfs/libxfs/xfs_cksum.h
> > +++ b/fs/xfs/libxfs/xfs_cksum.h
> > @@ -76,7 +76,10 @@ xfs_verify_cksum(char *buffer, size_t length, unsigned long cksum_offset)
> >  {
> >       uint32_t crc = xfs_start_cksum_safe(buffer, length, cksum_offset);
> >
> > -     return *(__le32 *)(buffer + cksum_offset) == xfs_end_cksum(crc);
> > +     if (IS_ENABLED(CONFIG_DISABLE_FS_CSUM_VERIFICATION))
> > +             return 1;
> > +     else
> > +             return *(__le32 *)(buffer + cksum_offset) == xfs_end_cksum(crc);
> >  }
> >
> >  #endif /* _XFS_CKSUM_H */
> > --
> > 2.38.0.413.g74048e4d9e-goog
> >
>
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diff mbox series

Patch

diff --git a/fs/xfs/libxfs/xfs_cksum.h b/fs/xfs/libxfs/xfs_cksum.h
index 999a290cfd72..ba55b1afa382 100644
--- a/fs/xfs/libxfs/xfs_cksum.h
+++ b/fs/xfs/libxfs/xfs_cksum.h
@@ -76,7 +76,10 @@  xfs_verify_cksum(char *buffer, size_t length, unsigned long cksum_offset)
 {
 	uint32_t crc = xfs_start_cksum_safe(buffer, length, cksum_offset);
 
-	return *(__le32 *)(buffer + cksum_offset) == xfs_end_cksum(crc);
+	if (IS_ENABLED(CONFIG_DISABLE_FS_CSUM_VERIFICATION))
+		return 1;
+	else
+		return *(__le32 *)(buffer + cksum_offset) == xfs_end_cksum(crc);
 }
 
 #endif /* _XFS_CKSUM_H */