linux-kernel - Re: [PATCH 3.12 01/58] nfsd: fix problem with setting ACL on directories

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Date:	Wed, 16 Mar 2016 13:24:04 +0100
From:	Sergio Gelato <Sergio.Gelato@...ro.su.se>
To:	Jiri Slaby <jslaby@...e.cz>
Cc:	stable@...r.kernel.org, linux-kernel@...r.kernel.org,
	NeilBrown <neilb@...e.com>
Subject: Re: [PATCH 3.12 01/58] nfsd: fix problem with setting ACL on
 directories

* Jiri Slaby [2016-03-16 11:58:46 +0100]:
> From: NeilBrown <neilb@...e.com>
> 
> 3.12-stable review patch.  If anyone has any objections, please let me know.

> If a non-inherited ACL is set on a directory, nfsd will try to set the Posix
> default ACL to NULL.  This gets converted to "" by generic_setxattr().
> As "" is not a valid posix acl attribute value, this results in an error.
> 
> So instead of setting the xattr to NULL, remove it.

There is similar code in nfsd_set_posix_acl() further down in the same source
file which skips the vfs_removexattr() call for default ACLs on non-directories
(there shouldn't be too many of these) and ignores ENODATA returns from
vfs_removexattr(). Are these precautions guaranteed to be unnecessary here in
set_nfsv4_acl_one() ?

> Fixes: ba1816b40a ("nfsd: fix NFS regression")
> Signed-off-by: NeilBrown <neilb@...e.com>
> Cc: Sergio Gelato <Sergio.Gelato@...ro.su.se>
> Signed-off-by: Jiri Slaby <jslaby@...e.cz>
> ---
>  fs/nfsd/vfs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> index fafac65804d6..e5f146c7c871 100644
> --- a/fs/nfsd/vfs.c
> +++ b/fs/nfsd/vfs.c
> @@ -510,7 +510,7 @@ set_nfsv4_acl_one(struct dentry *dentry, struct posix_acl *pacl, char *key)
>  	int error = 0;
>  
>  	if (!pacl)
> -		return vfs_setxattr(dentry, key, NULL, 0, 0);
> +		return vfs_removexattr(dentry, key);
>  
>  	buflen = posix_acl_xattr_size(pacl->a_count);
>  	buf = kmalloc(buflen, GFP_KERNEL);
> -- 
> 2.7.3
>