xfs_acl.c

linux 内核源代码

/*
 * Copyright (c) 2001-2002,2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_bit.h"
#include "xfs_inum.h"
#include "xfs_ag.h"
#include "xfs_dir2.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dir2_sf.h"
#include "xfs_attr_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_btree.h"
#include "xfs_acl.h"
#include "xfs_attr.h"
#include "xfs_vnodeops.h"

#include <linux/capability.h>
#include <linux/posix_acl_xattr.h>

STATIC int	xfs_acl_setmode(bhv_vnode_t *, xfs_acl_t *, int *);
STATIC void     xfs_acl_filter_mode(mode_t, xfs_acl_t *);
STATIC void	xfs_acl_get_endian(xfs_acl_t *);
STATIC int	xfs_acl_access(uid_t, gid_t, xfs_acl_t *, mode_t, cred_t *);
STATIC int	xfs_acl_invalid(xfs_acl_t *);
STATIC void	xfs_acl_sync_mode(mode_t, xfs_acl_t *);
STATIC void	xfs_acl_get_attr(bhv_vnode_t *, xfs_acl_t *, int, int, int *);
STATIC void	xfs_acl_set_attr(bhv_vnode_t *, xfs_acl_t *, int, int *);
STATIC int	xfs_acl_allow_set(bhv_vnode_t *, int);

kmem_zone_t *xfs_acl_zone;


/*
 * Test for existence of access ACL attribute as efficiently as possible.
 */
int
xfs_acl_vhasacl_access(
	bhv_vnode_t	*vp)
{
	int		error;

	xfs_acl_get_attr(vp, NULL, _ACL_TYPE_ACCESS, ATTR_KERNOVAL, &error);
	return (error == 0);
}

/*
 * Test for existence of default ACL attribute as efficiently as possible.
 */
int
xfs_acl_vhasacl_default(
	bhv_vnode_t	*vp)
{
	int		error;

	if (!VN_ISDIR(vp))
		return 0;
	xfs_acl_get_attr(vp, NULL, _ACL_TYPE_DEFAULT, ATTR_KERNOVAL, &error);
	return (error == 0);
}

/*
 * Convert from extended attribute representation to in-memory for XFS.
 */
STATIC int
posix_acl_xattr_to_xfs(
	posix_acl_xattr_header	*src,
	size_t			size,
	xfs_acl_t		*dest)
{
	posix_acl_xattr_entry	*src_entry;
	xfs_acl_entry_t		*dest_entry;
	int			n;

	if (!src || !dest)
		return EINVAL;

	if (size < sizeof(posix_acl_xattr_header))
		return EINVAL;

	if (src->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
		return EOPNOTSUPP;

	memset(dest, 0, sizeof(xfs_acl_t));
	dest->acl_cnt = posix_acl_xattr_count(size);
	if (dest->acl_cnt < 0 || dest->acl_cnt > XFS_ACL_MAX_ENTRIES)
		return EINVAL;

	/*
	 * acl_set_file(3) may request that we set default ACLs with
	 * zero length -- defend (gracefully) against that here.
	 */
	if (!dest->acl_cnt)
		return 0;

	src_entry = (posix_acl_xattr_entry *)((char *)src + sizeof(*src));
	dest_entry = &dest->acl_entry[0];

	for (n = 0; n < dest->acl_cnt; n++, src_entry++, dest_entry++) {
		dest_entry->ae_perm = le16_to_cpu(src_entry->e_perm);
		if (_ACL_PERM_INVALID(dest_entry->ae_perm))
			return EINVAL;
		dest_entry->ae_tag  = le16_to_cpu(src_entry->e_tag);
		switch(dest_entry->ae_tag) {
		case ACL_USER:
		case ACL_GROUP:
			dest_entry->ae_id = le32_to_cpu(src_entry->e_id);
			break;
		case ACL_USER_OBJ:
		case ACL_GROUP_OBJ:
		case ACL_MASK:
		case ACL_OTHER:
			dest_entry->ae_id = ACL_UNDEFINED_ID;
			break;
		default:
			return EINVAL;
		}
	}
	if (xfs_acl_invalid(dest))
		return EINVAL;

	return 0;
}

/*
 * Comparison function called from xfs_sort().
 * Primary key is ae_tag, secondary key is ae_id.
 */
STATIC int
xfs_acl_entry_compare(
	const void	*va,
	const void	*vb)
{
	xfs_acl_entry_t	*a = (xfs_acl_entry_t *)va,
			*b = (xfs_acl_entry_t *)vb;

	if (a->ae_tag == b->ae_tag)
		return (a->ae_id - b->ae_id);
	return (a->ae_tag - b->ae_tag);
}

/*
 * Convert from in-memory XFS to extended attribute representation.
 */
STATIC int
posix_acl_xfs_to_xattr(
	xfs_acl_t		*src,
	posix_acl_xattr_header	*dest,
	size_t			size)
{
	int			n;
	size_t			new_size = posix_acl_xattr_size(src->acl_cnt);
	posix_acl_xattr_entry	*dest_entry;
	xfs_acl_entry_t		*src_entry;

	if (size < new_size)
		return -ERANGE;

	/* Need to sort src XFS ACL by <ae_tag,ae_id> */
	xfs_sort(src->acl_entry, src->acl_cnt, sizeof(src->acl_entry[0]),
		 xfs_acl_entry_compare);

	dest->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
	dest_entry = &dest->a_entries[0];
	src_entry = &src->acl_entry[0];
	for (n = 0; n < src->acl_cnt; n++, dest_entry++, src_entry++) {
		dest_entry->e_perm = cpu_to_le16(src_entry->ae_perm);
		if (_ACL_PERM_INVALID(src_entry->ae_perm))
			return -EINVAL;
		dest_entry->e_tag  = cpu_to_le16(src_entry->ae_tag);
		switch (src_entry->ae_tag) {
		case ACL_USER:
		case ACL_GROUP:
			dest_entry->e_id = cpu_to_le32(src_entry->ae_id);
				break;
		case ACL_USER_OBJ:
		case ACL_GROUP_OBJ:
		case ACL_MASK:
		case ACL_OTHER:
			dest_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
			break;
		default:
			return -EINVAL;
		}
	}
	return new_size;
}

int
xfs_acl_vget(
	bhv_vnode_t	*vp,
	void		*acl,
	size_t		size,
	int		kind)
{
	int			error;
	xfs_acl_t		*xfs_acl = NULL;
	posix_acl_xattr_header	*ext_acl = acl;
	int			flags = 0;

	VN_HOLD(vp);
	if(size) {
		if (!(_ACL_ALLOC(xfs_acl))) {
			error = ENOMEM;
			goto out;
		}
		memset(xfs_acl, 0, sizeof(xfs_acl_t));
	} else
		flags = ATTR_KERNOVAL;

	xfs_acl_get_attr(vp, xfs_acl, kind, flags, &error);
	if (error)
		goto out;

	if (!size) {
		error = -posix_acl_xattr_size(XFS_ACL_MAX_ENTRIES);
	} else {
		if (xfs_acl_invalid(xfs_acl)) {
			error = EINVAL;
			goto out;
		}
		if (kind == _ACL_TYPE_ACCESS) {
			bhv_vattr_t	va;

			va.va_mask = XFS_AT_MODE;
			error = xfs_getattr(xfs_vtoi(vp), &va, 0);
			if (error)
				goto out;
			xfs_acl_sync_mode(va.va_mode, xfs_acl);
		}
		error = -posix_acl_xfs_to_xattr(xfs_acl, ext_acl, size);
	}
out:
	VN_RELE(vp);
	if(xfs_acl)
		_ACL_FREE(xfs_acl);
	return -error;
}

int
xfs_acl_vremove(
	bhv_vnode_t	*vp,
	int		kind)
{
	int		error;

	VN_HOLD(vp);
	error = xfs_acl_allow_set(vp, kind);
	if (!error) {
		error = xfs_attr_remove(xfs_vtoi(vp),
						kind == _ACL_TYPE_DEFAULT?
						SGI_ACL_DEFAULT: SGI_ACL_FILE,
						ATTR_ROOT);
		if (error == ENOATTR)
			error = 0;	/* 'scool */
	}
	VN_RELE(vp);
	return -error;
}

int
xfs_acl_vset(
	bhv_vnode_t		*vp,
	void			*acl,
	size_t			size,
	int			kind)
{
	posix_acl_xattr_header	*ext_acl = acl;
	xfs_acl_t		*xfs_acl;
	int			error;
	int			basicperms = 0; /* more than std unix perms? */

	if (!acl)
		return -EINVAL;

	if (!(_ACL_ALLOC(xfs_acl)))
		return -ENOMEM;

	error = posix_acl_xattr_to_xfs(ext_acl, size, xfs_acl);
	if (error) {
		_ACL_FREE(xfs_acl);
		return -error;
	}
	if (!xfs_acl->acl_cnt) {
		_ACL_FREE(xfs_acl);
		return 0;
	}

	VN_HOLD(vp);
	error = xfs_acl_allow_set(vp, kind);
	if (error)
		goto out;

	/* Incoming ACL exists, set file mode based on its value */
	if (kind == _ACL_TYPE_ACCESS)
		xfs_acl_setmode(vp, xfs_acl, &basicperms);

	/*
	 * If we have more than std unix permissions, set up the actual attr.
	 * Otherwise, delete any existing attr.  This prevents us from
	 * having actual attrs for permissions that can be stored in the
	 * standard permission bits.
	 */
	if (!basicperms) {
		xfs_acl_set_attr(vp, xfs_acl, kind, &error);
	} else {
		xfs_acl_vremove(vp, _ACL_TYPE_ACCESS);
	}

out:
	VN_RELE(vp);
	_ACL_FREE(xfs_acl);
	return -error;
}

int
xfs_acl_iaccess(
	xfs_inode_t	*ip,
	mode_t		mode,
	cred_t		*cr)
{
	xfs_acl_t	*acl;
	int		rval;

	if (!(_ACL_ALLOC(acl)))
		return -1;

	/* If the file has no ACL return -1. */
	rval = sizeof(xfs_acl_t);
	if (xfs_attr_fetch(ip, SGI_ACL_FILE, SGI_ACL_FILE_SIZE,
			(char *)acl, &rval, ATTR_ROOT | ATTR_KERNACCESS, cr)) {
		_ACL_FREE(acl);
		return -1;
	}
	xfs_acl_get_endian(acl);

	/* If the file has an empty ACL return -1. */
	if (acl->acl_cnt == XFS_ACL_NOT_PRESENT) {
		_ACL_FREE(acl);
		return -1;
	}

	/* Synchronize ACL with mode bits */
	xfs_acl_sync_mode(ip->i_d.di_mode, acl);

	rval = xfs_acl_access(ip->i_d.di_uid, ip->i_d.di_gid, acl, mode, cr);
	_ACL_FREE(acl);
	return rval;
}

STATIC int
xfs_acl_allow_set(
	bhv_vnode_t	*vp,
	int		kind)
{
	xfs_inode_t	*ip = xfs_vtoi(vp);
	bhv_vattr_t	va;
	int		error;

	if (vp->i_flags & (S_IMMUTABLE|S_APPEND))
		return EPERM;
	if (kind == _ACL_TYPE_DEFAULT && !VN_ISDIR(vp))
		return ENOTDIR;
	if (vp->i_sb->s_flags & MS_RDONLY)
		return EROFS;
	va.va_mask = XFS_AT_UID;
	error = xfs_getattr(ip, &va, 0);
	if (error)
		return error;
	if (va.va_uid != current->fsuid && !capable(CAP_FOWNER))
		return EPERM;
	return error;
}

/*
 * The access control process to determine the access permission:
 *	if uid == file owner id, use the file owner bits.
 *	if gid == file owner group id, use the file group bits.
 *	scan ACL for a matching user or group, and use matched entry
 *	permission. Use total permissions of all matching group entries,
 *	until all acl entries are exhausted. The final permission produced
 *	by matching acl entry or entries needs to be & with group permission.
 *	if not owner, owning group, or matching entry in ACL, use file
 *	other bits.  
 */
STATIC int
xfs_acl_capability_check(
	mode_t		mode,
	cred_t		*cr)
{
	if ((mode & ACL_READ) && !capable_cred(cr, CAP_DAC_READ_SEARCH))
		return EACCES;
	if ((mode & ACL_WRITE) && !capable_cred(cr, CAP_DAC_OVERRIDE))
		return EACCES;
	if ((mode & ACL_EXECUTE) && !capable_cred(cr, CAP_DAC_OVERRIDE))
		return EACCES;

	return 0;
}

/*
 * Note: cr is only used here for the capability check if the ACL test fails.
 *       It is not used to find out the credentials uid or groups etc, as was
 *       done in IRIX. It is assumed that the uid and groups for the current
 *       thread are taken from "current" instead of the cr parameter.
 */
STATIC int
xfs_acl_access(
	uid_t		fuid,
	gid_t		fgid,
	xfs_acl_t	*fap,
	mode_t		md,
	cred_t		*cr)
{
	xfs_acl_entry_t	matched;
	int		i, allows;
	int		maskallows = -1;	/* true, but not 1, either */
	int		seen_userobj = 0;

	matched.ae_tag = 0;	/* Invalid type */
	matched.ae_perm = 0;
	md >>= 6;	/* Normalize the bits for comparison */

	for (i = 0; i < fap->acl_cnt; i++) {
		/*
		 * Break out if we've got a user_obj entry or
		 * a user entry and the mask (and have processed USER_OBJ)
		 */
		if (matched.ae_tag == ACL_USER_OBJ)
			break;
		if (matched.ae_tag == ACL_USER) {
			if (maskallows != -1 && seen_userobj)
				break;
			if (fap->acl_entry[i].ae_tag != ACL_MASK &&
			    fap->acl_entry[i].ae_tag != ACL_USER_OBJ)
				continue;
		}
		/* True if this entry allows the requested access */
		allows = ((fap->acl_entry[i].ae_perm & md) == md);

		switch (fap->acl_entry[i].ae_tag) {
		case ACL_USER_OBJ:
			seen_userobj = 1;
			if (fuid != current->fsuid)
				continue;
			matched.ae_tag = ACL_USER_OBJ;