[PATCH] xfs: check for negatives in xfs_exchange_range_checks()

[PATCH] xfs: check for negatives in xfs_exchange_range_checks()

[Dan Carpenter]

The fxr->file1_offset and fxr->file2_offset variables come from the user
in xfs_ioc_exchange_range().  They are size loff_t which is an s64.
Check the they aren't negative.

Fixes: 9a64d9b3109d ("xfs: introduce new file range exchange ioctl")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
From static analysis.  Untested.  Sorry!

 fs/xfs/xfs_exchrange.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/xfs/xfs_exchrange.c b/fs/xfs/xfs_exchrange.c
index c8a655c92c92..3465e152d928 100644
--- a/fs/xfs/xfs_exchrange.c
+++ b/fs/xfs/xfs_exchrange.c
@@ -337,6 +337,9 @@ xfs_exchange_range_checks(
 	if (IS_SWAPFILE(inode1) || IS_SWAPFILE(inode2))
 		return -ETXTBSY;
 
+	if (fxr->file1_offset < 0 || fxr->file2_offset < 0)
+		return -EINVAL;
+
 	size1 = i_size_read(inode1);
 	size2 = i_size_read(inode2);
 
-- 
2.43.0

Re: [PATCH] xfs: check for negatives in xfs_exchange_range_checks()

[Markus Elfring]

…
> Check the they aren't negative.

Would you like to use the word “that” (instead of “the”) in this sentence?

Regards,
Markus

Re: [PATCH] xfs: check for negatives in xfs_exchange_range_checks()

[Christoph Hellwig]

On Sat, May 04, 2024 at 02:27:36PM +0300, Dan Carpenter wrote:
> The fxr->file1_offset and fxr->file2_offset variables come from the user
> in xfs_ioc_exchange_range().  They are size loff_t which is an s64.
> Check the they aren't negative.
> 
> Fixes: 9a64d9b3109d ("xfs: introduce new file range exchange ioctl")

In this commit file1_offset and file2_offset are u64.  They used to
be u64 in the initial submission, but we changed that as part of the
review process.

Re: [PATCH] xfs: check for negatives in xfs_exchange_range_checks()

[Dan Carpenter]

On Mon, May 06, 2024 at 11:06:17PM -0700, Christoph Hellwig wrote:
> On Sat, May 04, 2024 at 02:27:36PM +0300, Dan Carpenter wrote:
> > The fxr->file1_offset and fxr->file2_offset variables come from the user
> > in xfs_ioc_exchange_range().  They are size loff_t which is an s64.
> > Check the they aren't negative.
> > 
> > Fixes: 9a64d9b3109d ("xfs: introduce new file range exchange ioctl")
> 
> In this commit file1_offset and file2_offset are u64.  They used to
> be u64 in the initial submission, but we changed that as part of the
> review process.

I've just checked again, and I think it was loff_t in that commit.
There are two related structs, the one that's userspace API and the
one that's internal.  The userspace API is u64 but internally it's
loff_t.

fs/xfs/libxfs/xfs_fs.h
   818  struct xfs_exchange_range {
   819          __s32           file1_fd;
   820          __u32           pad;            /* must be zeroes */
   821          __u64           file1_offset;   /* file1 offset, bytes */
   822          __u64           file2_offset;   /* file2 offset, bytes */
   823          __u64           length;         /* bytes to exchange */
   824  
   825          __u64           flags;          /* see XFS_EXCHANGE_RANGE_* below */
   826  };

fs/xfs/xfs_exchrange.h
    16  struct xfs_exchrange {
    17          struct file             *file1;
    18          struct file             *file2;
    19  
    20          loff_t                  file1_offset;
    21          loff_t                  file2_offset;
    22          u64                     length;
    23  
    24          u64                     flags;  /* XFS_EXCHANGE_RANGE flags */
    25  };

regards,
dan carpenter

Re: [PATCH] xfs: check for negatives in xfs_exchange_range_checks()

[Christoph Hellwig]

On Tue, May 07, 2024 at 09:33:40AM +0300, Dan Carpenter wrote:
> On Mon, May 06, 2024 at 11:06:17PM -0700, Christoph Hellwig wrote:
> > On Sat, May 04, 2024 at 02:27:36PM +0300, Dan Carpenter wrote:
> > > The fxr->file1_offset and fxr->file2_offset variables come from the user
> > > in xfs_ioc_exchange_range().  They are size loff_t which is an s64.
> > > Check the they aren't negative.
> > > 
> > > Fixes: 9a64d9b3109d ("xfs: introduce new file range exchange ioctl")
> > 
> > In this commit file1_offset and file2_offset are u64.  They used to
> > be u64 in the initial submission, but we changed that as part of the
> > review process.
> 
> I've just checked again, and I think it was loff_t in that commit.
> There are two related structs, the one that's userspace API and the
> one that's internal.  The userspace API is u64 but internally it's
> loff_t.

Ah, yes.  The in-kernel ones probably just needs to move to use u64
as well.

Re: [PATCH] xfs: check for negatives in xfs_exchange_range_checks()

[Darrick J. Wong]

On Mon, May 06, 2024 at 11:40:25PM -0700, Christoph Hellwig wrote:
> On Tue, May 07, 2024 at 09:33:40AM +0300, Dan Carpenter wrote:
> > On Mon, May 06, 2024 at 11:06:17PM -0700, Christoph Hellwig wrote:
> > > On Sat, May 04, 2024 at 02:27:36PM +0300, Dan Carpenter wrote:
> > > > The fxr->file1_offset and fxr->file2_offset variables come from the user
> > > > in xfs_ioc_exchange_range().  They are size loff_t which is an s64.
> > > > Check the they aren't negative.
> > > > 
> > > > Fixes: 9a64d9b3109d ("xfs: introduce new file range exchange ioctl")
> > > 
> > > In this commit file1_offset and file2_offset are u64.  They used to
> > > be u64 in the initial submission, but we changed that as part of the
> > > review process.
> > 
> > I've just checked again, and I think it was loff_t in that commit.
> > There are two related structs, the one that's userspace API and the
> > one that's internal.  The userspace API is u64 but internally it's
> > loff_t.
> 
> Ah, yes.  The in-kernel ones probably just needs to move to use u64
> as well.

I don't think we want userspace to be able to exchangerange data at file
positions that they can't read or write with a standard fs syscall.

--D

Re: [PATCH] xfs: check for negatives in xfs_exchange_range_checks()

[Darrick J. Wong]

On Sat, May 04, 2024 at 02:27:36PM +0300, Dan Carpenter wrote:
> The fxr->file1_offset and fxr->file2_offset variables come from the user
> in xfs_ioc_exchange_range().  They are size loff_t which is an s64.
> Check the they aren't negative.
> 
> Fixes: 9a64d9b3109d ("xfs: introduce new file range exchange ioctl")
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> ---
> From static analysis.  Untested.  Sorry!

Not a fan of this        ^^^^^^^^

> 
>  fs/xfs/xfs_exchrange.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/fs/xfs/xfs_exchrange.c b/fs/xfs/xfs_exchrange.c
> index c8a655c92c92..3465e152d928 100644
> --- a/fs/xfs/xfs_exchrange.c
> +++ b/fs/xfs/xfs_exchrange.c
> @@ -337,6 +337,9 @@ xfs_exchange_range_checks(
>  	if (IS_SWAPFILE(inode1) || IS_SWAPFILE(inode2))
>  		return -ETXTBSY;
>  
> +	if (fxr->file1_offset < 0 || fxr->file2_offset < 0)
> +		return -EINVAL;

but this looks right to me.

If you actually test your changes, then
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D


> +
>  	size1 = i_size_read(inode1);
>  	size2 = i_size_read(inode2);
>  
> -- 
> 2.43.0
> 
> 

Re: [PATCH] xfs: check for negatives in xfs_exchange_range_checks()

[Dave Chinner]

On Sat, May 04, 2024 at 02:27:36PM +0300, Dan Carpenter wrote:
> The fxr->file1_offset and fxr->file2_offset variables come from the user
> in xfs_ioc_exchange_range().  They are size loff_t which is an s64.
> Check the they aren't negative.
> 
> Fixes: 9a64d9b3109d ("xfs: introduce new file range exchange ioctl")
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> ---
> From static analysis.  Untested.  Sorry!
> 
>  fs/xfs/xfs_exchrange.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/fs/xfs/xfs_exchrange.c b/fs/xfs/xfs_exchrange.c
> index c8a655c92c92..3465e152d928 100644
> --- a/fs/xfs/xfs_exchrange.c
> +++ b/fs/xfs/xfs_exchrange.c
> @@ -337,6 +337,9 @@ xfs_exchange_range_checks(
>  	if (IS_SWAPFILE(inode1) || IS_SWAPFILE(inode2))
>  		return -ETXTBSY;
>  
> +	if (fxr->file1_offset < 0 || fxr->file2_offset < 0)
> +		return -EINVAL;

Aren't the operational offset/lengths already checked for underflow
and overflow via xfs_exchange_range_verify_area()?

-Dave.
-- 
Dave Chinner
david@fromorbit.com

Re: [PATCH] xfs: check for negatives in xfs_exchange_range_checks()

[Darrick J. Wong]

On Wed, May 08, 2024 at 11:29:15AM +1000, Dave Chinner wrote:
> On Sat, May 04, 2024 at 02:27:36PM +0300, Dan Carpenter wrote:
> > The fxr->file1_offset and fxr->file2_offset variables come from the user
> > in xfs_ioc_exchange_range().  They are size loff_t which is an s64.
> > Check the they aren't negative.
> > 
> > Fixes: 9a64d9b3109d ("xfs: introduce new file range exchange ioctl")
> > Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> > ---
> > From static analysis.  Untested.  Sorry!
> > 
> >  fs/xfs/xfs_exchrange.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/fs/xfs/xfs_exchrange.c b/fs/xfs/xfs_exchrange.c
> > index c8a655c92c92..3465e152d928 100644
> > --- a/fs/xfs/xfs_exchrange.c
> > +++ b/fs/xfs/xfs_exchrange.c
> > @@ -337,6 +337,9 @@ xfs_exchange_range_checks(
> >  	if (IS_SWAPFILE(inode1) || IS_SWAPFILE(inode2))
> >  		return -ETXTBSY;
> >  
> > +	if (fxr->file1_offset < 0 || fxr->file2_offset < 0)
> > +		return -EINVAL;
> 
> Aren't the operational offset/lengths already checked for underflow
> and overflow via xfs_exchange_range_verify_area()?

Oh, yeah, they are.  I was just thinking surely I wrote some tests to
pass in garbage offsets and bounce back out...

--D

> -Dave.
> -- 
> Dave Chinner
> david@fromorbit.com

Re: [PATCH] xfs: check for negatives in xfs_exchange_range_checks()

[Dan Carpenter]

On Wed, May 08, 2024 at 11:29:15AM +1000, Dave Chinner wrote:
> On Sat, May 04, 2024 at 02:27:36PM +0300, Dan Carpenter wrote:
> > The fxr->file1_offset and fxr->file2_offset variables come from the user
> > in xfs_ioc_exchange_range().  They are size loff_t which is an s64.
> > Check the they aren't negative.
> > 
> > Fixes: 9a64d9b3109d ("xfs: introduce new file range exchange ioctl")
> > Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> > ---
> > From static analysis.  Untested.  Sorry!
> > 
> >  fs/xfs/xfs_exchrange.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/fs/xfs/xfs_exchrange.c b/fs/xfs/xfs_exchrange.c
> > index c8a655c92c92..3465e152d928 100644
> > --- a/fs/xfs/xfs_exchrange.c
> > +++ b/fs/xfs/xfs_exchrange.c
> > @@ -337,6 +337,9 @@ xfs_exchange_range_checks(
> >  	if (IS_SWAPFILE(inode1) || IS_SWAPFILE(inode2))
> >  		return -ETXTBSY;
> >  
> > +	if (fxr->file1_offset < 0 || fxr->file2_offset < 0)
> > +		return -EINVAL;
> 
> Aren't the operational offset/lengths already checked for underflow
> and overflow via xfs_exchange_range_verify_area()?

Ah right.  Smatch complains in the middle of the two calls to
xfs_exchange_range_verify_area().  (It get's called in different places
depending on if the XFS_EXCHANGE_RANGE_TO_EOF flag is set).

regards,
dan carpenter