[f2fs-dev] [PATCH] f2fs: fix fileattr_set unsupported attribute handling

[f2fs-dev] [PATCH] f2fs: fix fileattr_set unsupported attribute handling

[Harry Austen]

FS_IOC_SETFLAGS ioctl should return EOPNOTSUPP if the file attribute
(e.g. FS_NOCOW_FL) is not supported, rather than silently ignoring it
and returning success.

Fixes: 9b1bb01c8ae7 (f2fs: convert to fileattr)
Signed-off-by: Harry Austen <harryausten@hotmail.co.uk>
---
 fs/f2fs/file.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 92ec2699bc85..061bf35c2582 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -3085,9 +3085,8 @@ int f2fs_fileattr_set(struct user_namespace *mnt_userns,
 		return -EIO;
 	if (!f2fs_is_checkpoint_ready(F2FS_I_SB(inode)))
 		return -ENOSPC;
-	if (fsflags & ~F2FS_GETTABLE_FS_FL)
+	if (fsflags & ~F2FS_SETTABLE_FS_FL)
 		return -EOPNOTSUPP;
-	fsflags &= F2FS_SETTABLE_FS_FL;
 	if (!fa->flags_valid)
 		mask &= FS_COMMON_FL;
 
-- 
2.34.1



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Re: [f2fs-dev] [PATCH] f2fs: fix fileattr_set unsupported attribute handling

[Chao Yu]

On 2022/1/22 20:59, Harry Austen wrote:
> FS_IOC_SETFLAGS ioctl should return EOPNOTSUPP if the file attribute
> (e.g. FS_NOCOW_FL) is not supported, rather than silently ignoring it
> and returning success.
> 
> Fixes: 9b1bb01c8ae7 (f2fs: convert to fileattr)
> Signed-off-by: Harry Austen <harryausten@hotmail.co.uk>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,


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Re: [f2fs-dev] [PATCH] f2fs: fix fileattr_set unsupported attribute handling

[Eric Biggers]

On Sat, Jan 22, 2022 at 12:59:03PM +0000, Harry Austen wrote:
> FS_IOC_SETFLAGS ioctl should return EOPNOTSUPP if the file attribute
> (e.g. FS_NOCOW_FL) is not supported, rather than silently ignoring it
> and returning success.
> 
> Fixes: 9b1bb01c8ae7 (f2fs: convert to fileattr)
> Signed-off-by: Harry Austen <harryausten@hotmail.co.uk>
> ---
>  fs/f2fs/file.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 92ec2699bc85..061bf35c2582 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -3085,9 +3085,8 @@ int f2fs_fileattr_set(struct user_namespace *mnt_userns,
>  		return -EIO;
>  	if (!f2fs_is_checkpoint_ready(F2FS_I_SB(inode)))
>  		return -ENOSPC;
> -	if (fsflags & ~F2FS_GETTABLE_FS_FL)
> +	if (fsflags & ~F2FS_SETTABLE_FS_FL)
>  		return -EOPNOTSUPP;
> -	fsflags &= F2FS_SETTABLE_FS_FL;
>  	if (!fa->flags_valid)
>  		mask &= FS_COMMON_FL;

This is intentional, and matches what ext4 does; see the comment in the ext4
implementation of this:

        /*
         * chattr(1) grabs flags via GETFLAGS, modifies the result and
         * passes that to SETFLAGS. So we cannot easily make SETFLAGS
         * more restrictive than just silently masking off visible but
         * not settable flags as we always did.
         */

Also, even if this patch was correct, the Fixes tag is wrong.

- Eric


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Re: [f2fs-dev] [PATCH] f2fs: fix fileattr_set unsupported attribute handling

[Harry Austen]

On Monday, 24 January 2022 19:25:44 GMT Eric Biggers wrote:
> On Sat, Jan 22, 2022 at 12:59:03PM +0000, Harry Austen wrote:
> > FS_IOC_SETFLAGS ioctl should return EOPNOTSUPP if the file attribute
> > (e.g. FS_NOCOW_FL) is not supported, rather than silently ignoring it
> > and returning success.
> > 
> > Fixes: 9b1bb01c8ae7 (f2fs: convert to fileattr)
> > Signed-off-by: Harry Austen <harryausten@hotmail.co.uk>
> > ---
> > 
> >  fs/f2fs/file.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 92ec2699bc85..061bf35c2582 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -3085,9 +3085,8 @@ int f2fs_fileattr_set(struct user_namespace
> > *mnt_userns,> 
> >  		return -EIO;
> >  	
> >  	if (!f2fs_is_checkpoint_ready(F2FS_I_SB(inode)))
> >  	
> >  		return -ENOSPC;
> > 
> > -	if (fsflags & ~F2FS_GETTABLE_FS_FL)
> > +	if (fsflags & ~F2FS_SETTABLE_FS_FL)
> > 
> >  		return -EOPNOTSUPP;
> > 
> > -	fsflags &= F2FS_SETTABLE_FS_FL;
> > 
> >  	if (!fa->flags_valid)
> >  	
> >  		mask &= FS_COMMON_FL;
> 
> This is intentional, and matches what ext4 does; see the comment in the ext4
> implementation of this:
> 
>         /*
>          * chattr(1) grabs flags via GETFLAGS, modifies the result and
>          * passes that to SETFLAGS. So we cannot easily make SETFLAGS
>          * more restrictive than just silently masking off visible but
>          * not settable flags as we always did.
>          */

Ah, my apologies. I thought it looked a little too obvious. Clearly I
should have looked at the ext4 code. Please disregard this patch.

Is there anything else that could be done to improve unsettable
attribute handling? For example, is there a reason FS_NOCOW_FL is
gettable but not settable? Could it be added to the settable list?

> 
> Also, even if this patch was correct, the Fixes tag is wrong.

Having looked at this a bit more, I assume you are saying this due to
the missing double quotes around the commit summary? (just so I know for
next time as this is my first attempt at sending a kernel patch)

> 
> - Eric

Many thanks for your help Eric,
Harry




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Re: [f2fs-dev] [PATCH] f2fs: fix fileattr_set unsupported attribute handling

[Eric Biggers]

On Tue, Jan 25, 2022 at 10:01:49PM +0000, Harry Austen wrote:
> On Monday, 24 January 2022 19:25:44 GMT Eric Biggers wrote:
> > On Sat, Jan 22, 2022 at 12:59:03PM +0000, Harry Austen wrote:
> > > FS_IOC_SETFLAGS ioctl should return EOPNOTSUPP if the file attribute
> > > (e.g. FS_NOCOW_FL) is not supported, rather than silently ignoring it
> > > and returning success.
> > > 
> > > Fixes: 9b1bb01c8ae7 (f2fs: convert to fileattr)
> > > Signed-off-by: Harry Austen <harryausten@hotmail.co.uk>
> > > ---
> > > 
> > >  fs/f2fs/file.c | 3 +--
> > >  1 file changed, 1 insertion(+), 2 deletions(-)
> > > 
> > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > > index 92ec2699bc85..061bf35c2582 100644
> > > --- a/fs/f2fs/file.c
> > > +++ b/fs/f2fs/file.c
> > > @@ -3085,9 +3085,8 @@ int f2fs_fileattr_set(struct user_namespace
> > > *mnt_userns,> 
> > >  		return -EIO;
> > >  	
> > >  	if (!f2fs_is_checkpoint_ready(F2FS_I_SB(inode)))
> > >  	
> > >  		return -ENOSPC;
> > > 
> > > -	if (fsflags & ~F2FS_GETTABLE_FS_FL)
> > > +	if (fsflags & ~F2FS_SETTABLE_FS_FL)
> > > 
> > >  		return -EOPNOTSUPP;
> > > 
> > > -	fsflags &= F2FS_SETTABLE_FS_FL;
> > > 
> > >  	if (!fa->flags_valid)
> > >  	
> > >  		mask &= FS_COMMON_FL;
> > 
> > This is intentional, and matches what ext4 does; see the comment in the ext4
> > implementation of this:
> > 
> >         /*
> >          * chattr(1) grabs flags via GETFLAGS, modifies the result and
> >          * passes that to SETFLAGS. So we cannot easily make SETFLAGS
> >          * more restrictive than just silently masking off visible but
> >          * not settable flags as we always did.
> >          */
> 
> Ah, my apologies. I thought it looked a little too obvious. Clearly I
> should have looked at the ext4 code. Please disregard this patch.
> 
> Is there anything else that could be done to improve unsettable
> attribute handling? For example, is there a reason FS_NOCOW_FL is
> gettable but not settable? Could it be added to the settable list?

A lot of flags are gettable by FS_IOC_GETFLAGS but not settable by
FS_IOC_SETFLAGS, typically because they can only be set through a dedicated
interface.  For example, the encrypt flag can only be set using
FS_IOC_SET_ENCRYPTION_POLICY, or via inheritance.

> > 
> > Also, even if this patch was correct, the Fixes tag is wrong.
> 
> Having looked at this a bit more, I assume you are saying this due to
> the missing double quotes around the commit summary? (just so I know for
> next time as this is my first attempt at sending a kernel patch)
> 

There's that, but more importantly the commit you listed is wrong.  The relevant
code was added by an earlier commit, and that commit just moved it.

- Eric


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