[PATCH] Subject: [PATCH] xfs: fix sgid inheritance for subdirectories inheriting default acls [V3]

[Carlos Maiolino]

Hi, any comments on this one?

On Fri, Jun 21, 2013 at 02:45:53PM -0300, Carlos Maiolino wrote:
> XFS removes sgid bits of subdirectories under a directory containing a default
> acl.
> 
> When a default acl is set, it implies xfs to call xfs_setattr_nonsize() in its
> code path. Such function is shared among mkdir and chmod system calls, and
> does some checks unneeded by mkdir (calling inode_change_ok()). Such checks
> remove sgid bit from the inode after it has been granted.
> 
> With this patch, we extend the meaning of XFS_ATTR_NOACL flag to avoid these
> checks when acls are being inherited (thanks hch).
> 
> Also, xfs_setattr_mode, doesn't need to re-check for group id and capabilities
> permissions, this only implies in another try to remove sgid bit from the
> directories. Such check is already done either on inode_change_ok() or
> xfs_setattr_nonsize().
> 
> Changelog:
> 
> V2: Extends the meaning of XFS_ATTR_NOACL instead of wrap the tests into another
>     function
> 
> V3: Remove S_ISDIR check in xfs_setattr_nonsize() from the patch
> 
> Signed-off-by: Carlos Maiolino <cmaiolino at redhat.com>
> ---
>  fs/xfs/xfs_iops.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index ca9ecaa..2e5aca8 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -467,9 +467,6 @@ xfs_setattr_mode(
>  	ASSERT(tp);
>  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
>  
> -	if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
> -		mode &= ~S_ISGID;
> -
>  	ip->i_d.di_mode &= S_IFMT;
>  	ip->i_d.di_mode |= mode & ~S_IFMT;
>  
> @@ -495,15 +492,18 @@ xfs_setattr_nonsize(
>  
>  	trace_xfs_setattr(ip);
>  
> -	if (mp->m_flags & XFS_MOUNT_RDONLY)
> -		return XFS_ERROR(EROFS);
> +	/* If acls are being inherited, we already have this checked */
> +	if (!(flags & XFS_ATTR_NOACL)) {
> +		if (mp->m_flags & XFS_MOUNT_RDONLY)
> +			return XFS_ERROR(EROFS);
>  
> -	if (XFS_FORCED_SHUTDOWN(mp))
> -		return XFS_ERROR(EIO);
> +		if (XFS_FORCED_SHUTDOWN(mp))
> +			return XFS_ERROR(EIO);
>  
> -	error = -inode_change_ok(inode, iattr);
> -	if (error)
> -		return XFS_ERROR(error);
> +		error = -inode_change_ok(inode, iattr);
> +		if (error)
> +			return XFS_ERROR(error);
> +	}
>  
>  	ASSERT((mask & ATTR_SIZE) == 0);
>  
> -- 
> 1.8.1.4
> 
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-- 
Carlos