339 lines
9.0 KiB
C
339 lines
9.0 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 1999-2006 Robert N. M. Watson
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* All rights reserved.
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*
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* This software was developed by Robert Watson for the TrustedBSD Project.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Developed by the TrustedBSD Project.
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*
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* ACL support routines specific to POSIX.1e access control lists. These are
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* utility routines for code common across file systems implementing POSIX.1e
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* ACLs.
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*/
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#include <sys/cdefs.h>
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#if 0
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__FBSDID("$FreeBSD: head/sys/kern/subr_acl_posix1e.c 341827 2018-12-11 19:32:16Z mjg $");
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#endif
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__KERNEL_RCSID(0, "$NetBSD: subr_acl_posix1e.c,v 1.1 2020/05/16 18:31:50 christos Exp $");
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/module.h>
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#include <sys/systm.h>
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#include <sys/mount.h>
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#include <sys/vnode.h>
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#include <sys/kauth.h>
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#include <sys/errno.h>
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#include <sys/stat.h>
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#include <sys/acl.h>
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/*
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* For the purposes of filesystems maintaining the _OBJ entries in an inode
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* with a mode_t field, this routine converts a mode_t entry to an
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* acl_perm_t.
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*/
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acl_perm_t
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acl_posix1e_mode_to_perm(acl_tag_t tag, mode_t mode)
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{
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acl_perm_t perm = 0;
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switch(tag) {
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case ACL_USER_OBJ:
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if (mode & S_IXUSR)
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perm |= ACL_EXECUTE;
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if (mode & S_IRUSR)
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perm |= ACL_READ;
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if (mode & S_IWUSR)
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perm |= ACL_WRITE;
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return (perm);
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case ACL_GROUP_OBJ:
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if (mode & S_IXGRP)
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perm |= ACL_EXECUTE;
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if (mode & S_IRGRP)
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perm |= ACL_READ;
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if (mode & S_IWGRP)
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perm |= ACL_WRITE;
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return (perm);
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case ACL_OTHER:
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if (mode & S_IXOTH)
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perm |= ACL_EXECUTE;
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if (mode & S_IROTH)
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perm |= ACL_READ;
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if (mode & S_IWOTH)
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perm |= ACL_WRITE;
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return (perm);
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default:
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printf("%s: invalid tag (%u)\n", __func__, tag);
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return (0);
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}
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}
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/*
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* Given inode information (uid, gid, mode), return an acl entry of the
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* appropriate type.
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*/
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struct acl_entry
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acl_posix1e_mode_to_entry(acl_tag_t tag, uid_t uid, gid_t gid, mode_t mode)
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{
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struct acl_entry acl_entry;
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acl_entry.ae_tag = tag;
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acl_entry.ae_perm = acl_posix1e_mode_to_perm(tag, mode);
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acl_entry.ae_entry_type = 0;
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acl_entry.ae_flags = 0;
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switch(tag) {
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case ACL_USER_OBJ:
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acl_entry.ae_id = uid;
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break;
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case ACL_GROUP_OBJ:
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acl_entry.ae_id = gid;
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break;
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case ACL_OTHER:
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acl_entry.ae_id = ACL_UNDEFINED_ID;
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break;
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default:
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acl_entry.ae_id = ACL_UNDEFINED_ID;
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printf("acl_posix1e_mode_to_entry: invalid tag (%d)\n", tag);
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}
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return (acl_entry);
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}
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/*
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* Utility function to generate a file mode given appropriate ACL entries.
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*/
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mode_t
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acl_posix1e_perms_to_mode(struct acl_entry *acl_user_obj_entry,
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struct acl_entry *acl_group_obj_entry, struct acl_entry *acl_other_entry)
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{
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mode_t mode;
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mode = 0;
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if (acl_user_obj_entry->ae_perm & ACL_EXECUTE)
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mode |= S_IXUSR;
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if (acl_user_obj_entry->ae_perm & ACL_READ)
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mode |= S_IRUSR;
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if (acl_user_obj_entry->ae_perm & ACL_WRITE)
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mode |= S_IWUSR;
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if (acl_group_obj_entry->ae_perm & ACL_EXECUTE)
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mode |= S_IXGRP;
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if (acl_group_obj_entry->ae_perm & ACL_READ)
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mode |= S_IRGRP;
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if (acl_group_obj_entry->ae_perm & ACL_WRITE)
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mode |= S_IWGRP;
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if (acl_other_entry->ae_perm & ACL_EXECUTE)
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mode |= S_IXOTH;
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if (acl_other_entry->ae_perm & ACL_READ)
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mode |= S_IROTH;
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if (acl_other_entry->ae_perm & ACL_WRITE)
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mode |= S_IWOTH;
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return (mode);
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}
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/*
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* Utility function to generate a file mode given a complete POSIX.1e access
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* ACL. Note that if the ACL is improperly formed, this may result in a
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* panic.
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*/
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mode_t
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acl_posix1e_acl_to_mode(struct acl *acl)
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{
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struct acl_entry *acl_mask, *acl_user_obj, *acl_group_obj, *acl_other;
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int i;
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/*
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* Find the ACL entries relevant to a POSIX permission mode.
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*/
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acl_user_obj = acl_group_obj = acl_other = acl_mask = NULL;
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for (i = 0; i < acl->acl_cnt; i++) {
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switch (acl->acl_entry[i].ae_tag) {
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case ACL_USER_OBJ:
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acl_user_obj = &acl->acl_entry[i];
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break;
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case ACL_GROUP_OBJ:
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acl_group_obj = &acl->acl_entry[i];
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break;
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case ACL_OTHER:
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acl_other = &acl->acl_entry[i];
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break;
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case ACL_MASK:
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acl_mask = &acl->acl_entry[i];
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break;
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case ACL_USER:
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case ACL_GROUP:
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break;
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default:
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panic("acl_posix1e_acl_to_mode: bad ae_tag");
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}
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}
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if (acl_user_obj == NULL || acl_group_obj == NULL || acl_other == NULL)
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panic("acl_posix1e_acl_to_mode: missing base ae_tags");
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/*
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* POSIX.1e specifies that if there is an ACL_MASK entry, we replace
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* the mode "group" bits with its permissions. If there isn't, we
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* use the ACL_GROUP_OBJ permissions.
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*/
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if (acl_mask != NULL)
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return (acl_posix1e_perms_to_mode(acl_user_obj, acl_mask,
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acl_other));
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else
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return (acl_posix1e_perms_to_mode(acl_user_obj, acl_group_obj,
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acl_other));
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}
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/*
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* Perform a syntactic check of the ACL, sufficient to allow an implementing
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* filesystem to determine if it should accept this and rely on the POSIX.1e
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* ACL properties.
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*/
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int
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acl_posix1e_check(struct acl *acl)
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{
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int num_acl_user_obj, num_acl_user, num_acl_group_obj, num_acl_group;
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int num_acl_mask, num_acl_other, i;
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/*
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* Verify that the number of entries does not exceed the maximum
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* defined for acl_t.
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*
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* Verify that the correct number of various sorts of ae_tags are
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* present:
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* Exactly one ACL_USER_OBJ
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* Exactly one ACL_GROUP_OBJ
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* Exactly one ACL_OTHER
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* If any ACL_USER or ACL_GROUP entries appear, then exactly one
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* ACL_MASK entry must also appear.
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*
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* Verify that all ae_perm entries are in ACL_PERM_BITS.
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*
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* Verify all ae_tag entries are understood by this implementation.
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*
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* Note: Does not check for uniqueness of qualifier (ae_id) field.
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*/
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num_acl_user_obj = num_acl_user = num_acl_group_obj = num_acl_group =
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num_acl_mask = num_acl_other = 0;
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if (acl->acl_cnt > ACL_MAX_ENTRIES)
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return (EINVAL);
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for (i = 0; i < acl->acl_cnt; i++) {
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struct acl_entry *ae = &acl->acl_entry[i];
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/*
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* Check for a valid tag.
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*/
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switch(ae->ae_tag) {
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case ACL_USER_OBJ:
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ae->ae_id = ACL_UNDEFINED_ID; /* XXX */
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if (ae->ae_id != ACL_UNDEFINED_ID)
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return (EINVAL);
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num_acl_user_obj++;
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break;
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case ACL_GROUP_OBJ:
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ae->ae_id = ACL_UNDEFINED_ID; /* XXX */
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if (ae->ae_id != ACL_UNDEFINED_ID)
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return (EINVAL);
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num_acl_group_obj++;
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break;
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case ACL_USER:
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if (ae->ae_id == ACL_UNDEFINED_ID)
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return (EINVAL);
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num_acl_user++;
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break;
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case ACL_GROUP:
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if (ae->ae_id == ACL_UNDEFINED_ID)
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return (EINVAL);
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num_acl_group++;
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break;
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case ACL_OTHER:
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ae->ae_id = ACL_UNDEFINED_ID; /* XXX */
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if (ae->ae_id != ACL_UNDEFINED_ID)
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return (EINVAL);
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num_acl_other++;
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break;
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case ACL_MASK:
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ae->ae_id = ACL_UNDEFINED_ID; /* XXX */
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if (ae->ae_id != ACL_UNDEFINED_ID)
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return (EINVAL);
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num_acl_mask++;
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break;
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default:
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return (EINVAL);
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}
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/*
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* Check for valid perm entries.
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*/
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if ((acl->acl_entry[i].ae_perm | ACL_PERM_BITS) !=
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ACL_PERM_BITS)
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return (EINVAL);
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}
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if ((num_acl_user_obj != 1) || (num_acl_group_obj != 1) ||
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(num_acl_other != 1) || (num_acl_mask != 0 && num_acl_mask != 1))
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return (EINVAL);
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if (((num_acl_group != 0) || (num_acl_user != 0)) &&
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(num_acl_mask != 1))
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return (EINVAL);
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return (0);
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}
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/*
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* Given a requested mode for a new object, and a default ACL, combine the
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* two to produce a new mode. Be careful not to clear any bits that aren't
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* intended to be affected by the POSIX.1e ACL. Eventually, this might also
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* take the cmask as an argument, if we push that down into
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* per-filesystem-code.
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*/
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mode_t
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acl_posix1e_newfilemode(mode_t cmode, struct acl *dacl)
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{
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mode_t mode;
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mode = cmode;
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/*
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* The current composition policy is that a permission bit must be
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* set in *both* the ACL and the requested creation mode for it to
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* appear in the resulting mode/ACL. First clear any possibly
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* effected bits, then reconstruct.
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*/
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mode &= ACL_PRESERVE_MASK;
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mode |= (ACL_OVERRIDE_MASK & cmode & acl_posix1e_acl_to_mode(dacl));
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return (mode);
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}
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