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linux-sg2042/fs/xfs/xfs_acl.c

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/*
* 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;
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;
int mask_required = 0;
int i, j;
if (!aclp)
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(
bhv_vnode_t *vp,
xfs_acl_t *aclp,
int kind,
int flags,
int *error)
{
int len = sizeof(xfs_acl_t);
ASSERT((flags & ATTR_KERNOVAL) ? (aclp == NULL) : 1);
flags |= ATTR_ROOT;
*error = xfs_attr_get(xfs_vtoi(vp),
kind == _ACL_TYPE_ACCESS ?
SGI_ACL_FILE : SGI_ACL_DEFAULT,
(char *)aclp, &len, flags, sys_cred);
if (*error || (flags & ATTR_KERNOVAL))
return;
xfs_acl_get_endian(aclp);
}
/*
* Set the EA with the ACL and do endian conversion.
*/
STATIC void
xfs_acl_set_attr(
bhv_vnode_t *vp,
xfs_acl_t *aclp,
int kind,
int *error)
{
xfs_acl_entry_t *ace, *newace, *end;
xfs_acl_t *newacl;
int len;
if (!(_ACL_ALLOC(newacl))) {
*error = ENOMEM;
return;
}
len = sizeof(xfs_acl_t) -
(sizeof(xfs_acl_entry_t) * (XFS_ACL_MAX_ENTRIES - aclp->acl_cnt));
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);
*error = xfs_attr_set(xfs_vtoi(vp),
kind == _ACL_TYPE_ACCESS ?
SGI_ACL_FILE: SGI_ACL_DEFAULT,
(char *)newacl, len, ATTR_ROOT);
_ACL_FREE(newacl);
}
int
xfs_acl_vtoacl(
bhv_vnode_t *vp,
xfs_acl_t *access_acl,
xfs_acl_t *default_acl)
{
bhv_vattr_t va;
int error = 0;
if (access_acl) {
/*
* 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, 0, &error);
if (!error) {
/* Got the ACL, need the mode... */
va.va_mask = XFS_AT_MODE;
error = xfs_getattr(xfs_vtoi(vp), &va, 0);
}
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) {
xfs_acl_get_attr(vp, default_acl, _ACL_TYPE_DEFAULT, 0, &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(
bhv_vnode_t *vp,
mode_t mode,
xfs_acl_t *pdaclp)
{
xfs_acl_t *cacl;
int error = 0;
int basicperms = 0;
/*
* If the parent does not have a default ACL, or it's an
* invalid ACL, we're done.
*/
if (!vp)
return 0;
if (!pdaclp || 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.
*/
if (!(_ACL_ALLOC(cacl)))
return ENOMEM;
memcpy(cacl, pdaclp, sizeof(xfs_acl_t));
xfs_acl_filter_mode(mode, cacl);
xfs_acl_setmode(vp, cacl, &basicperms);
/*
* 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 (VN_ISDIR(vp))
xfs_acl_set_attr(vp, pdaclp, _ACL_TYPE_DEFAULT, &error);
if (!error && !basicperms)
xfs_acl_set_attr(vp, cacl, _ACL_TYPE_ACCESS, &error);
_ACL_FREE(cacl);
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(
bhv_vnode_t *vp,
xfs_acl_t *acl,
int *basicperms)
{
bhv_vattr_t va;
xfs_acl_entry_t *ap;
xfs_acl_entry_t *gap = NULL;
int i, error, nomask = 1;
*basicperms = 1;
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 = XFS_AT_MODE;
error = xfs_getattr(xfs_vtoi(vp), &va, 0);
if (error)
return error;
va.va_mask = XFS_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: /* more than just standard modes */
nomask = 0;
va.va_mode |= ap->ae_perm << 3;
*basicperms = 0;
break;
case ACL_OTHER:
va.va_mode |= ap->ae_perm;
break;
default: /* more than just standard modes */
*basicperms = 0;
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;
return xfs_setattr(xfs_vtoi(vp), &va, 0, sys_cred);
}
/*
* 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, 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, 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;
}
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