Return to xfs_acl.c CVS log

Up to [Development] / xfs-linux

convert over from struct acl and other ACL related types/macros to
an xfs_acl_t variant so we can tell what is XFS-specific and what
is not.  will help our transition to a common EA/ACL codebase while
keeping our existing ondisk format intact.

/*
 * Copyright (c) 2001 Silicon Graphics, Inc.  All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 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.
 *
 * Further, this software is distributed without any warranty that it is
 * free of the rightful claim of any third person regarding infringement
 * or the like.  Any license provided herein, whether implied or
 * otherwise, applies only to this software file.  Patent licenses, if
 * any, provided herein do not apply to combinations of this program with
 * other software, or any other product whatsoever.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write the Free Software Foundation, Inc., 59
 * Temple Place - Suite 330, Boston MA 02111-1307, USA.
 *
 * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
 * Mountain View, CA  94043, or:
 *
 * http://www.sgi.com
 *
 * For further information regarding this notice, see:
 *
 * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
 */

#include <xfs.h>

#define ACL_TYPE_ACCESS		0
#define ACL_TYPE_DEFAULT	1

#define SGI_ACL_FILE	"SGI_ACL_FILE"
#define SGI_ACL_DEFAULT	"SGI_ACL_DEFAULT"

#define ACL_PERM_NONE	0x00
#define ACL_READ	0x04
#define ACL_WRITE	0x02
#define ACL_EXECUTE	0x01

#define ACL_USER_OBJ	0x01
#define ACL_USER	0x02
#define ACL_GROUP_OBJ	0x04
#define ACL_GROUP	0x08
#define ACL_MASK	0x10
#define ACL_OTHER	0x20

STATIC int	xfs_acl_setmode(vnode_t *, xfs_acl_t *);
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 *aclp);
STATIC void	xfs_acl_sync_mode(mode_t mode, xfs_acl_t *acl);

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

	/* If the file has no ACL return -1. */
	if (xfs_attr_fetch(ip, SGI_ACL_FILE, (char *)&acl, sizeof(xfs_acl_t)))
		return -1;
	xfs_acl_get_endian(&acl);

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

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

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

/*
 * 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 maching 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)
{
	int i;
	xfs_acl_entry_t matched;
	int maskallows = -1;	/* true, but not 1, either */
	int allows;
        int seen_userobj = 0;

	matched.ae_tag = 0;	/* Invalid type */
	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;
			matched.ae_perm = allows;
			break;
		case ACL_USER:
			if (fap->acl_entry[i].ae_id != current->fsuid)
				continue;
			matched.ae_tag = ACL_USER;
			matched.ae_perm = allows;
			break;
		case ACL_GROUP_OBJ:
			if ((matched.ae_tag == ACL_GROUP_OBJ ||
			    matched.ae_tag == ACL_GROUP) && !allows)
				continue;
			if (!in_group_p(fgid))
				continue;
			matched.ae_tag = ACL_GROUP_OBJ;
			matched.ae_perm = allows;
			break;
		case ACL_GROUP:
			if ((matched.ae_tag == ACL_GROUP_OBJ ||
			    matched.ae_tag == ACL_GROUP) && !allows)
				continue;
			if (!in_group_p(fap->acl_entry[i].ae_id))
				continue;
			matched.ae_tag = ACL_GROUP;
			matched.ae_perm = allows;
			break;
		case ACL_MASK:
			maskallows = allows;
			break;
		case ACL_OTHER:
			if (matched.ae_tag != 0)
				continue;
			matched.ae_tag = ACL_OTHER;
			matched.ae_perm = allows;
			break;
		}
	}
	/*
	 * First possibility is that no matched entry allows access.
	 * The capability to override DAC may exist, so check for it.
	 */
	switch (matched.ae_tag) {
	case ACL_OTHER:
	case ACL_USER_OBJ:
		if (matched.ae_perm)
			return 0;
		break;
	case ACL_USER:
	case ACL_GROUP_OBJ:
	case ACL_GROUP:
		if (maskallows && matched.ae_perm)
			return 0;
		break;
	case 0:
		break;
	}
	return xfs_acl_capability_check(md, cr);
}

/*
 * ACL validity checker.
 *   This acl validation routine checks each ACL entry read in makes sense.
 */
STATIC int
xfs_acl_invalid(xfs_acl_t *aclp)
{
	xfs_acl_entry_t *entry, *e;
	int user = 0, group = 0, other = 0, mask = 0, mask_required = 0;
	int i, j;

	if (aclp == NULL)
		goto acl_invalid;

	if (aclp->acl_cnt > XFS_ACL_MAX_ENTRIES)
		goto acl_invalid;

	for (i = 0; i < aclp->acl_cnt; i++) {
		entry = &aclp->acl_entry[i];
		switch (entry->ae_tag) {
			case ACL_USER_OBJ:
				if (user++)
					goto acl_invalid;
				break;
			case ACL_GROUP_OBJ:
				if (group++)
					goto acl_invalid;
				break;
			case ACL_OTHER:
				if (other++)
					goto acl_invalid;
				break;
			case ACL_USER:
			case ACL_GROUP:
				for (j = i + 1; j < aclp->acl_cnt; j++) {
					e = &aclp->acl_entry[j];
					if (e->ae_id == entry->ae_id &&
					    e->ae_tag == entry->ae_tag)
						goto acl_invalid;
				}
				mask_required++;
				break;
			case ACL_MASK:
				if (mask++)
					goto acl_invalid;
				break;
			default:
				goto acl_invalid;
		}
	}
	if (!user || !group || !other || (mask_required && !mask))
		goto acl_invalid;
	else
		return 0;
acl_invalid:
	return EINVAL;
}

/*
 * Do ACL endian conversion.
 */
STATIC void
xfs_acl_get_endian(xfs_acl_t *aclp)
{
	xfs_acl_entry_t *ace, *end;

	INT_SET(aclp->acl_cnt, ARCH_CONVERT, aclp->acl_cnt);

	end = &aclp->acl_entry[0]+aclp->acl_cnt;
	for (ace=&aclp->acl_entry[0]; ace < end; ace++) {
		INT_SET(ace->ae_tag, ARCH_CONVERT, ace->ae_tag);
		INT_SET(ace->ae_id, ARCH_CONVERT, ace->ae_id);
		INT_SET(ace->ae_perm, ARCH_CONVERT, ace->ae_perm);
	}
}

/*
 * Get the ACL from the EA and do endian conversion.
 */
STATIC void
xfs_acl_get_attr(vnode_t *vp, xfs_acl_t *aclp, int kind, int *error)
{
	int len = sizeof(xfs_acl_t);

	VOP_ATTR_GET(vp, kind==ACL_TYPE_ACCESS ? SGI_ACL_FILE: SGI_ACL_DEFAULT, 
		     (char *)aclp, &len, ATTR_ROOT, sys_cred, *error);
	if (*error)
		return;
	xfs_acl_get_endian(aclp);
}

/*
 * Set the EA with the ACL and do endian conversion.
 */
STATIC void
xfs_acl_set_attr(vnode_t *vp, xfs_acl_t *aclp, int kind, int *error)
{
	xfs_acl_entry_t *ace, *newace, *end;
	xfs_acl_t newacl;
	int len = sizeof(xfs_acl_t);

	end = &aclp->acl_entry[0]+aclp->acl_cnt;
	for (ace = &aclp->acl_entry[0], newace = &newacl.acl_entry[0];
	     ace < end;
	     ace++, newace++) {
		INT_SET(newace->ae_tag, ARCH_CONVERT, ace->ae_tag);
		INT_SET(newace->ae_id, ARCH_CONVERT, ace->ae_id);
		INT_SET(newace->ae_perm, ARCH_CONVERT, ace->ae_perm);
	}
	INT_SET(newacl.acl_cnt, ARCH_CONVERT, aclp->acl_cnt);

	VOP_ATTR_SET(vp, kind==ACL_TYPE_ACCESS ? SGI_ACL_FILE: SGI_ACL_DEFAULT, 
		     (char *)&newacl, len, ATTR_ROOT, sys_cred, *error);
}

int
xfs_acl_vtoacl(vnode_t *vp, xfs_acl_t *access_acl, xfs_acl_t *default_acl)
{
	int error = 0;
	vattr_t	va;

	if (access_acl != NULL) {
		/*
		 * Get the Access ACL and the mode.  If either cannot
		 * be obtained for some reason, invalidate the access ACL.
		 */
                xfs_acl_get_attr(vp, access_acl, ACL_TYPE_ACCESS, &error);
		if (!error) {
			/* Got the ACL, need the mode... */
			va.va_mask = AT_MODE;
			VOP_GETATTR(vp, &va, 0, sys_cred, error);
		}

		if (error)
			access_acl->acl_cnt = XFS_ACL_NOT_PRESENT;
		else /* We have a good ACL and the file mode, synchronize. */
			xfs_acl_sync_mode(va.va_mode, access_acl);
	}

	if (default_acl != NULL) {
		xfs_acl_get_attr(vp, default_acl, ACL_TYPE_DEFAULT, &error);
		if (error)
			default_acl->acl_cnt = XFS_ACL_NOT_PRESENT;
	}
	return error;
}

/*
 * This function retrieves the parent directory's acl, processes it
 * and lets the child inherit the acl(s) that it should.
 */
int
xfs_acl_inherit(vnode_t *vp, vattr_t *vap, xfs_acl_t *pdaclp)
{
	xfs_acl_t cacl;
	int error = 0;

	/*
	 * If the parent does not have a default ACL, or it's an
	 * invalid ACL, we're done.
	 */
	if (vp == NULL)
		return (0);
	if (pdaclp == NULL || xfs_acl_invalid(pdaclp))
		return (0);

	/*
	 * Copy the default ACL of the containing directory to
	 * the access ACL of the new file and use the mode that
	 * was passed in to set up the correct initial values for
	 * the u::,g::[m::], and o:: entries.  This is what makes
	 * umask() "work" with ACL's.
	 */
        memcpy(&cacl, pdaclp, sizeof(cacl));
	xfs_acl_filter_mode(vap->va_mode, &cacl);

	/* Set the mode to the acl */ 
	xfs_acl_setmode(vp, &cacl);

	/*
	 * Set the default and access acl on the file.  The mode is already
	 * set on the file, so we don't need to worry about that.
	 *
	 * If the new file is a directory, its default ACL is a copy of
	 * the containing directory's default ACL.
	 *
	 */
	if (vp->v_type == VDIR)
		xfs_acl_set_attr(vp, pdaclp, ACL_TYPE_DEFAULT, &error);
	if (!error)
		xfs_acl_set_attr(vp, &cacl, ACL_TYPE_ACCESS, &error);
	return error;
}

STATIC int
xfs_acl_vget(vnode_t *vp, int kind, xfs_acl_t *acl)
{
	xfs_acl_t kacl;
	int size = sizeof(kacl);
	int error = 0;
	vattr_t	va;

	memset(&kacl, 0, size);
	xfs_acl_get_attr(vp, &kacl, kind, &error);

	if (!error && xfs_acl_invalid(&kacl))
		error = EINVAL;

	if (!error && (kind == ACL_TYPE_ACCESS)) {
		/* For Access ACLs, get the mode for synchronization. */
		va.va_mask = AT_MODE;
		VOP_GETATTR(vp, &va, 0, sys_cred, error);
	}

	/*
	 * If there was an error retrieving or validating the ACL or 
	 * an Access ACL and we had trouble synchronizing the mode with the
	 * ACL, then the ACL is deemed NOT PRESENT.
	 */
	if (error)
		kacl.acl_cnt = XFS_ACL_NOT_PRESENT;
	else if (kind == ACL_TYPE_ACCESS)
		/* Synchronize an Access ACL with the mode */
		xfs_acl_sync_mode(va.va_mode, &kacl);


	/*
	 * If the whole problem was that the requested ACL does not exist, then
	 * there is no problem.  Just copy out a NOT PRESENT ACL.  Otherwise,
	 * don't do the copyout (an error should leave user level data
	 * unchanged).
	 */
	if (error == ENOATTR)
		error = 0;

	if (!error && copyout((caddr_t)&kacl, (caddr_t)acl, sizeof(kacl)))
		error = EFAULT;
	return error;
}

int
xfs_acl_get(vnode_t *vp, xfs_acl_t *acl, xfs_acl_t *dacl)
{
	int error;
	int derror = 0;

	if (!acl && !dacl)
		return (EINVAL);

	VN_HOLD(vp);
	error = _MAC_VACCESS(vp, get_current_cred(), VREAD);
	if (!error) {
		if (acl)
			error = xfs_acl_vget(vp, ACL_TYPE_ACCESS, acl);
		if (dacl)
			derror = xfs_acl_vget(vp, ACL_TYPE_DEFAULT, dacl);
	}
	VN_RELE(vp);

	if (!error && derror)
		error = derror;
	return error;
}

STATIC int
xfs_acl_vset(vnode_t *vp, xfs_acl_t *acl)
{
	int error;

	/*
	 * Check for an ACL deletion (the caller specifies a NOT PRESENT ACL).
	 */
	if (acl->acl_cnt == XFS_ACL_NOT_PRESENT) {
		/* Deletion, remove the ACL if there is one. */
		VOP_ATTR_REMOVE(vp, SGI_ACL_FILE, ATTR_ROOT, sys_cred, error);
		if (error == ENOATTR) {
			/* There was no Access ACL to delete, no big deal. */
			error = 0;
		}
		return error;
	}

	/* The incoming ACL exists, so set the file mode based on it. */
	xfs_acl_setmode(vp, acl);

	xfs_acl_set_attr(vp, acl, ACL_TYPE_ACCESS, &error);
	return error;
}

STATIC int
xfs_dacl_vset(vnode_t *vp, xfs_acl_t *dacl)
{
	int	error = 0;

	if (dacl->acl_cnt != XFS_ACL_NOT_PRESENT) {
		/*  Apply the default ACL to the file */
		xfs_acl_set_attr(vp, dacl, ACL_TYPE_DEFAULT, &error);
	} else {
		/*
		 * Delete the ACL on the file.  If none is there, ignore the
		 * error.  Report other errors to the caller.
		 */
		VOP_ATTR_REMOVE(vp, SGI_ACL_DEFAULT, ATTR_ROOT, sys_cred,
				error);
		if (error == ENOATTR) {
			/* There was no default ACL to delete, no big deal. */
			error = 0;
		}
	}
	return error;
}

/*
 * Set the ACLs on a file system object.  Either or both the Access or
 * Default ACL may be set using this function.  If the 'acl' pointer is
 * non-NULL the Access ACL is set, if the 'dacl' pointer is non-NULL the
 * Default ACL is set.
 */
int
xfs_acl_set(vnode_t *vp, xfs_acl_t *acl, xfs_acl_t *dacl)
{
	xfs_acl_t kacl;
	xfs_acl_t kdacl;
	vattr_t va;
	int error;

	if (!acl && !dacl)
		return (EINVAL);
	if (acl) {
		if (copy_from_user(&kacl, acl, sizeof(kacl)))
			return (EFAULT);
		if (xfs_acl_invalid(&kacl) && kacl.acl_cnt != XFS_ACL_NOT_PRESENT)
			return (EINVAL);
	}
	if (dacl) {
		if (copy_from_user(&kdacl, dacl, sizeof(kdacl)))
			return (EFAULT);
		if (xfs_acl_invalid(&kdacl) && kdacl.acl_cnt != XFS_ACL_NOT_PRESENT)
			return (EINVAL);
	}
	VN_HOLD(vp);

	/*
	 * Only directories may have default acls
	 * Better not try to update a read-only file system.
	 */
	if (dacl && vp->v_type != VDIR)
		error = ENOTDIR;
	else if (vp->v_vfsp->vfs_flag & VFS_RDONLY)
		error = EROFS;
	else {
		error = _MAC_VACCESS(vp, NULL, VWRITE);
		if (!error) {
			va.va_mask = AT_UID;
			VOP_GETATTR(vp, &va, 0, NULL, error);
			if (!error && va.va_uid != current->fsuid &&
			    !capable(CAP_FOWNER))
				error = EACCES;
		}
		if (!error && acl)	/* Set the access ACL. */
			error = xfs_acl_vset(vp, &kacl);
		if (!error && dacl)	/* Set the default ACL. */
			error = xfs_dacl_vset(vp, &kdacl);
	}

	VN_RELE(vp);
	return error;
}

/*
 * Set up the correct mode on the file based on the supplied ACL.  This
 * makes sure that the mode on the file reflects the state of the
 * u::,g::[m::], and o:: entries in the ACL.  Since the mode is where
 * the ACL is going to get the permissions for these entries, we must
 * synchronize the mode whenever we set the ACL on a file.
 */
STATIC int
xfs_acl_setmode(vnode_t *vp, xfs_acl_t *acl)
{
	vattr_t		va;
	xfs_acl_entry_t	*gap = NULL;
	xfs_acl_entry_t	*ap;
	int		nomask = 1;
	int		i;
	int		error;

	if (acl->acl_cnt == XFS_ACL_NOT_PRESENT)
		return (0);

	/*
	 * Copy the u::, g::, o::, and m:: bits from the ACL into the
	 * mode.  The m:: bits take precedence over the g:: bits.
	 */
	va.va_mask = AT_MODE;
	VOP_GETATTR(vp, &va, 0, sys_cred, error);
	if (error)
		return error;

	va.va_mask = AT_MODE;
	va.va_mode &= ~(S_IRWXU|S_IRWXG|S_IRWXO);
	ap = acl->acl_entry;
	for (i = 0; i < acl->acl_cnt; ++i) {
		switch (ap->ae_tag) {
		case ACL_USER_OBJ:
			va.va_mode |= ap->ae_perm << 6;
			break;
		case ACL_GROUP_OBJ:
			gap = ap;
			break;
		case ACL_MASK:
			nomask = 0;
			va.va_mode |= ap->ae_perm << 3;
			break;
		case ACL_OTHER:
			va.va_mode |= ap->ae_perm;
			break;
		default:
			break;
		}
		ap++;
	}

	/* Set the group bits from ACL_GROUP_OBJ if there's no ACL_MASK */
	if (gap && nomask)
		va.va_mode |= gap->ae_perm << 3;

	VOP_SETATTR(vp, &va, 0, sys_cred, error);
	return error;
}

/*
 * The permissions for the special ACL entries (u::, g::[m::], o::) are
 * actually stored in the file mode (if there is both a group and a mask,
 * the group is stored in the ACL entry and the mask is stored on the file).
 * This allows the mode to remain automatically in sync with the ACL without
 * the need for a call-back to the ACL system at every point where the mode
 * could change.  This function takes the permissions from the specified mode
 * and places it in the supplied ACL.
 *
 * This implementation draws its validity from the fact that, when the ACL
 * was assigned, the mode was copied from the ACL.
 * If the mode did not change, therefore, the mode remains exactly what was
 * taken from the special ACL entries at assignment.
 * If a subsequent chmod() was done, the POSIX spec says that the change in
 * mode must cause an update to the ACL seen at user level and used for
 * access checks.  Before and after a mode change, therefore, the file mode
 * most accurately reflects what the special ACL entries should permit/deny.
 *
 * CAVEAT: If someone sets the SGI_ACL_FILE attribute directly,
 *         the existing mode bits will override whatever is in the
 *         ACL. Similarly, if there is a pre-existing ACL that was
 *         never in sync with its mode (owing to a bug in 6.5 and
 *         before), it will now magically (or mystically) be
 *         synchronized.  This could cause slight astonishment, but
 *         it is better than inconsistent permissions.
 *
 * The supplied ACL is a template that may contain any combination
 * of special entries.  These are treated as place holders when we fill
 * out the ACL.  This routine does not add or remove special entries, it
 * simply unites each special entry with its associated set of permissions.
 */
STATIC void
xfs_acl_sync_mode(mode_t mode, xfs_acl_t *acl)
{
	int i;
	int nomask = 1;
	xfs_acl_entry_t *ap;
	xfs_acl_entry_t *gap = NULL;

	/*
	 * Set ACL entries. POSIX1003.1eD16 requires that the MASK
	 * be set instead of the GROUP entry, if there is a MASK.
	 */
	for (ap = acl->acl_entry, i = 0; i < acl->acl_cnt; ap++, i++) {
		switch (ap->ae_tag) {
		case ACL_USER_OBJ:
			ap->ae_perm = (mode >> 6) & 0x7;
			break;
		case ACL_GROUP_OBJ:
			gap = ap;
			break;
		case ACL_MASK:
			nomask = 0;
			ap->ae_perm = (mode >> 3) & 0x7;
			break;
		case ACL_OTHER:
			ap->ae_perm = mode & 0x7;
			break;
		default:
			break;
		}
	}
	/* Set the ACL_GROUP_OBJ if there's no ACL_MASK */
	if (gap && nomask)
		gap->ae_perm = (mode >> 3) & 0x7;
}

/* 
 * When inheriting an Access ACL from a directory Default ACL,
 * the ACL bits are set to the intersection of the ACL default 
 * permission bits and the file permission bits in mode. If there
 * are no permission bits on the file then we must not give them
 * the ACL. This is what what makes umask() work with ACLs.
 */
STATIC void
xfs_acl_filter_mode(mode_t mode, xfs_acl_t *acl)
{
	int i;
	int nomask = 1;
	xfs_acl_entry_t *ap;
	xfs_acl_entry_t *gap = NULL;

	/*
	 * Set ACL entries. POSIX1003.1eD16 requires that the MASK
	 * be merged with GROUP entry, if there is a MASK.
	 */
	for (ap = acl->acl_entry, i = 0; i < acl->acl_cnt; ap++, i++) {
		switch (ap->ae_tag) {
		case ACL_USER_OBJ:
			ap->ae_perm &= (mode >> 6) & 0x7;
			break;
		case ACL_GROUP_OBJ:
			gap = ap;
			break;
		case ACL_MASK:
			nomask = 0;
			ap->ae_perm &= (mode >> 3) & 0x7;
			break;
		case ACL_OTHER:
			ap->ae_perm &= mode & 0x7;
			break;
		default:
			break;
		}
	}
	/* Set the ACL_GROUP_OBJ if there's no ACL_MASK */
	if (gap && nomask)
		gap->ae_perm &= (mode >> 3) & 0x7;
}