Re: [PATCH 1/2] kill attr_capable callbacks

[Timothy Shimmin <tes@sgi.com>]

Hi Christoph,

Looks reasonable to me - comparing xattr_permission() with
attr_user_capable() and attr_trusted_capable().
Also the xattr_permission() makes more sense with its MAY_WRITE
testing otherwise it looks like we'd be doing some unfair
tests in the getxattr case.

I'll run thru qa and check in soon.

--Tim


Christoph Hellwig wrote:
> No need for addition permission checks in the xattr handler,
> fs/xattr.c:xattr_permission() already does them, and in fact slightly
> more strict then what was in the attr_capable handlers.
> 
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> 
> Index: linux-2.6-xfs/fs/xfs/linux-2.6/xfs_iops.c
> ===================================================================
> --- linux-2.6-xfs.orig/fs/xfs/linux-2.6/xfs_iops.c	2008-04-29 21:32:56.000000000 +0200
> +++ linux-2.6-xfs/fs/xfs/linux-2.6/xfs_iops.c	2008-04-29 21:33:30.000000000 +0200
> @@ -747,15 +747,11 @@ xfs_vn_setxattr(
>  	char		*attr = (char *)name;
>  	attrnames_t	*namesp;
>  	int		xflags = 0;
> -	int		error;
>  
>  	namesp = attr_lookup_namespace(attr, attr_namespaces, ATTR_NAMECOUNT);
>  	if (!namesp)
>  		return -EOPNOTSUPP;
>  	attr += namesp->attr_namelen;
> -	error = namesp->attr_capable(vp, NULL);
> -	if (error)
> -		return error;
>  
>  	/* Convert Linux syscall to XFS internal ATTR flags */
>  	if (flags & XATTR_CREATE)
> @@ -777,15 +773,11 @@ xfs_vn_getxattr(
>  	char		*attr = (char *)name;
>  	attrnames_t	*namesp;
>  	int		xflags = 0;
> -	ssize_t		error;
>  
>  	namesp = attr_lookup_namespace(attr, attr_namespaces, ATTR_NAMECOUNT);
>  	if (!namesp)
>  		return -EOPNOTSUPP;
>  	attr += namesp->attr_namelen;
> -	error = namesp->attr_capable(vp, NULL);
> -	if (error)
> -		return error;
>  
>  	/* Convert Linux syscall to XFS internal ATTR flags */
>  	if (!size) {
> @@ -825,15 +817,12 @@ xfs_vn_removexattr(
>  	char		*attr = (char *)name;
>  	attrnames_t	*namesp;
>  	int		xflags = 0;
> -	int		error;
>  
>  	namesp = attr_lookup_namespace(attr, attr_namespaces, ATTR_NAMECOUNT);
>  	if (!namesp)
>  		return -EOPNOTSUPP;
>  	attr += namesp->attr_namelen;
> -	error = namesp->attr_capable(vp, NULL);
> -	if (error)
> -		return error;
> +
>  	xflags |= namesp->attr_flag;
>  	return namesp->attr_remove(vp, attr, xflags);
>  }
> Index: linux-2.6-xfs/fs/xfs/xfs_attr.c
> ===================================================================
> --- linux-2.6-xfs.orig/fs/xfs/xfs_attr.c	2008-04-29 21:32:25.000000000 +0200
> +++ linux-2.6-xfs/fs/xfs/xfs_attr.c	2008-04-29 21:32:51.000000000 +0200
> @@ -2622,43 +2622,6 @@ attr_lookup_namespace(
>  	return NULL;
>  }
>  
> -/*
> - * Some checks to prevent people abusing EAs to get over quota:
> - * - Don't allow modifying user EAs on devices/symlinks;
> - * - Don't allow modifying user EAs if sticky bit set;
> - */
> -STATIC int
> -attr_user_capable(
> -	bhv_vnode_t	*vp,
> -	cred_t		*cred)
> -{
> -	struct inode	*inode = vn_to_inode(vp);
> -
> -	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
> -		return -EPERM;
> -	if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode) &&
> -	    !capable(CAP_SYS_ADMIN))
> -		return -EPERM;
> -	if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
> -	    (current_fsuid(cred) != inode->i_uid) && !capable(CAP_FOWNER))
> -		return -EPERM;
> -	return 0;
> -}
> -
> -STATIC int
> -attr_trusted_capable(
> -	bhv_vnode_t	*vp,
> -	cred_t		*cred)
> -{
> -	struct inode	*inode = vn_to_inode(vp);
> -
> -	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
> -		return -EPERM;
> -	if (!capable(CAP_SYS_ADMIN))
> -		return -EPERM;
> -	return 0;
> -}
> -
>  STATIC int
>  attr_system_set(
>  	bhv_vnode_t *vp, char *name, void *data, size_t size, int xflags)
> @@ -2709,7 +2672,6 @@ struct attrnames attr_system = {
>  	.attr_get	= attr_system_get,
>  	.attr_set	= attr_system_set,
>  	.attr_remove	= attr_system_remove,
> -	.attr_capable	= (attrcapable_t)fs_noerr,
>  };
>  
>  struct attrnames attr_trusted = {
> @@ -2719,7 +2681,6 @@ struct attrnames attr_trusted = {
>  	.attr_get	= attr_generic_get,
>  	.attr_set	= attr_generic_set,
>  	.attr_remove	= attr_generic_remove,
> -	.attr_capable	= attr_trusted_capable,
>  };
>  
>  struct attrnames attr_secure = {
> @@ -2729,7 +2690,6 @@ struct attrnames attr_secure = {
>  	.attr_get	= attr_generic_get,
>  	.attr_set	= attr_generic_set,
>  	.attr_remove	= attr_generic_remove,
> -	.attr_capable	= (attrcapable_t)fs_noerr,
>  };
>  
>  struct attrnames attr_user = {
> @@ -2738,7 +2698,6 @@ struct attrnames attr_user = {
>  	.attr_get	= attr_generic_get,
>  	.attr_set	= attr_generic_set,
>  	.attr_remove	= attr_generic_remove,
> -	.attr_capable	= attr_user_capable,
>  };
>  
>  struct attrnames *attr_namespaces[] =
> Index: linux-2.6-xfs/fs/xfs/xfs_attr.h
> ===================================================================
> --- linux-2.6-xfs.orig/fs/xfs/xfs_attr.h	2008-04-29 21:33:38.000000000 +0200
> +++ linux-2.6-xfs/fs/xfs/xfs_attr.h	2008-04-29 21:33:52.000000000 +0200
> @@ -42,7 +42,6 @@ typedef int (*attrset_t)(bhv_vnode_t *, 
>  typedef int (*attrget_t)(bhv_vnode_t *, char *, void *, size_t, int);
>  typedef int (*attrremove_t)(bhv_vnode_t *, char *, int);
>  typedef int (*attrexists_t)(bhv_vnode_t *);
> -typedef int (*attrcapable_t)(bhv_vnode_t *, struct cred *);
>  
>  typedef struct attrnames {
>  	char *		attr_name;
> @@ -52,7 +51,6 @@ typedef struct attrnames {
>  	attrset_t	attr_set;
>  	attrremove_t	attr_remove;
>  	attrexists_t	attr_exists;
> -	attrcapable_t	attr_capable;
>  } attrnames_t;
>  
>  #define ATTR_NAMECOUNT	4
>