449 lines
10 KiB
C
449 lines
10 KiB
C
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/*-
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* Copyright (c) 1999 Robert N. M. Watson
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* All rights reserved.
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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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* $FreeBSD$
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*/
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/*
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* Support functionality for the POSIX.1e ACL interface
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* These calls are intended only to be called within the library.
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*/
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#include <sys/types.h>
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#include <sys/acl.h>
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#include <errno.h>
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#include <grp.h>
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#include <pwd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "acl_support.h"
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#define ACL_STRING_PERM_WRITE 'w'
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#define ACL_STRING_PERM_READ 'r'
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#define ACL_STRING_PERM_EXEC 'x'
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#define ACL_STRING_PERM_NONE '-'
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/*
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* acl_entry_compare -- compare two acl_entry structures to determine the
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* order they should appear in. Used by acl_sort to sort ACL entries into
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* the kernel-desired order -- i.e., the order useful for evaluation and
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* O(n) validity checking. Beter to have an O(nlogn) sort in userland and
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* an O(n) in kernel than to have both in kernel.
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*/
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typedef int (*compare)(const void *, const void *);
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static int
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acl_entry_compare(struct acl_entry *a, struct acl_entry *b)
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{
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/*
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* First, sort between tags -- conveniently defined in the correct
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* order for verification.
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*/
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if (a->ae_tag < b->ae_tag)
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return (-1);
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if (a->ae_tag > b->ae_tag)
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return (1);
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/*
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* Next compare uids/gids on appropriate types.
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*/
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if (a->ae_tag == ACL_USER || a->ae_tag == ACL_GROUP) {
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if (a->ae_id < b->ae_id)
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return (-1);
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if (a->ae_id > b->ae_id)
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return (1);
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/* shouldn't be equal, fall through to the invalid case */
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}
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/*
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* Don't know how to sort multiple entries of the rest--either it's
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* a bad entry, or there shouldn't be more than one. Ignore and the
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* validity checker can get it later.
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*/
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return (0);
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}
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/*
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* acl_sort -- sort ACL entries.
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* Give the opportunity to fail, althouh we don't currently have a way
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* to fail.
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*/
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int
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acl_sort(acl_t acl)
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{
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qsort(&acl->acl_entry[0], acl->acl_cnt, sizeof(struct acl_entry),
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(compare) acl_entry_compare);
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return (0);
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}
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/*
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* acl_posix1e -- use a heuristic to determine if this is a POSIX.1e
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* semantics ACL. This will be used by other routines to determine if
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* they should call acl_sort() on the ACL before submitting to the kernel,
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* as the POSIX.1e ACL semantics code requires sorted ACL submission.
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* Also, acl_valid will use this to determine if it understands the
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* semantics enough to check that the ACL is correct.
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*/
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int
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acl_posix1e(acl_t acl)
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{
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int i;
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/* assume it's POSIX.1e, and return 0 if otherwise */
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for (i = 0; i < acl->acl_cnt; i++) {
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/* is the tag type POSIX.1e? */
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switch(acl->acl_entry[i].ae_tag) {
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case ACL_USER_OBJ:
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case ACL_USER:
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case ACL_GROUP_OBJ:
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case ACL_GROUP:
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case ACL_MASK:
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case ACL_OTHER:
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break;
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default:
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return (0);
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}
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/* are the permissions POSIX.1e, or FreeBSD extensions? */
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if (((acl->acl_entry[i].ae_perm | ACL_POSIX1E_BITS) !=
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ACL_POSIX1E_BITS) &&
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((acl->acl_entry[i].ae_perm | ACL_PERM_BITS) !=
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ACL_PERM_BITS))
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return (0);
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}
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return(1);
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}
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/*
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* acl_check -- given an ACL, check its validity. This is mirrored from
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* code in sys/kern/kern_acl.c, and if changes are made in one, they should
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* be made in the other also. This copy of acl_check is made available
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* in userland for the benefit of processes wanting to check ACLs for
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* validity before submitting them to the kernel, or for performing
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* in userland file system checking. Needless to say, the kernel makes
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* the real checks on calls to get/setacl.
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*
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* See the comments in kernel for explanation -- just briefly, it assumes
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* an already sorted ACL, and checks based on that assumption. The
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* POSIX.1e interface, acl_valid(), will perform the sort before calling
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* this. Returns 0 on success, EINVAL on failure.
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*/
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int
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acl_check(struct acl *acl)
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{
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struct acl_entry *entry; /* current entry */
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uid_t obj_uid=-1, obj_gid=-1, highest_uid=0, highest_gid=0;
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int stage = ACL_USER_OBJ;
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int i = 0;
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int count_user_obj=0, count_user=0, count_group_obj=0,
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count_group=0, count_mask=0, count_other=0;
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/* printf("acl_check: checking acl with %d entries\n", acl->acl_cnt); */
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while (i < acl->acl_cnt) {
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entry = &acl->acl_entry[i];
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if ((entry->ae_perm | ACL_PERM_BITS) != ACL_PERM_BITS)
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return (EINVAL);
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switch(entry->ae_tag) {
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case ACL_USER_OBJ:
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/* printf("acl_check: %d: ACL_USER_OBJ\n", i); */
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if (stage > ACL_USER_OBJ)
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return (EINVAL);
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stage = ACL_USER;
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count_user_obj++;
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obj_uid = entry->ae_id;
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break;
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case ACL_USER:
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/* printf("acl_check: %d: ACL_USER\n", i); */
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if (stage > ACL_USER)
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return (EINVAL);
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stage = ACL_USER;
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if (entry->ae_id == obj_uid)
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return (EINVAL);
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if (count_user && (entry->ae_id <= highest_uid))
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return (EINVAL);
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highest_uid = entry->ae_id;
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count_user++;
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break;
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case ACL_GROUP_OBJ:
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/* printf("acl_check: %d: ACL_GROUP_OBJ\n", i); */
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if (stage > ACL_GROUP_OBJ)
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return (EINVAL);
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stage = ACL_GROUP;
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count_group_obj++;
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obj_gid = entry->ae_id;
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break;
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case ACL_GROUP:
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/* printf("acl_check: %d: ACL_GROUP\n", i); */
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if (stage > ACL_GROUP)
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return (EINVAL);
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stage = ACL_GROUP;
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if (entry->ae_id == obj_gid)
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return (EINVAL);
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if (count_group && (entry->ae_id <= highest_gid))
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return (EINVAL);
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highest_gid = entry->ae_id;
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count_group++;
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break;
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case ACL_MASK:
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/* printf("acl_check: %d: ACL_MASK\n", i); */
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if (stage > ACL_MASK)
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return (EINVAL);
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stage = ACL_MASK;
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count_mask++;
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break;
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case ACL_OTHER:
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/* printf("acl_check: %d: ACL_OTHER\n", i); */
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if (stage > ACL_OTHER)
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return (EINVAL);
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stage = ACL_OTHER;
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count_other++;
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break;
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default:
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/* printf("acl_check: %d: INVALID\n", i); */
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return (EINVAL);
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}
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i++;
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}
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if (count_user_obj != 1)
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return (EINVAL);
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if (count_group_obj != 1)
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return (EINVAL);
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if (count_mask != 0 && count_mask != 1)
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return (EINVAL);
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if (count_other != 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 uid/gid, return a username/groupname for the text form of an ACL
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* XXX NOT THREAD SAFE, RELIES ON GETPWUID, GETGRGID
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* XXX USES *PW* AND *GR* WHICH ARE STATEFUL AND THEREFORE THIS ROUTINE
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* MAY HAVE SIDE-EFFECTS
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*/
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int
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acl_id_to_name(acl_tag_t tag, uid_t id, ssize_t buf_len, char *buf)
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{
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struct group *g;
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struct passwd *p;
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int i;
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switch(tag) {
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case ACL_USER:
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p = getpwuid(id);
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if (!p)
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i = snprintf(buf, buf_len, "%d", id);
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else
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i = snprintf(buf, buf_len, "%s", p->pw_name);
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if (i >= buf_len) {
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errno = ENOMEM;
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return (-1);
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}
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return (0);
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case ACL_GROUP:
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g = getgrgid(id);
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if (!g)
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i = snprintf(buf, buf_len, "%d", id);
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else
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i = snprintf(buf, buf_len, "%s", g->gr_name);
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if (i >= buf_len) {
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errno = ENOMEM;
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return (-1);
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}
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return (0);
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default:
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return (EINVAL);
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}
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}
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/*
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* Given a username/groupname from a text form of an ACL, return the uid/gid
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* XXX NOT THREAD SAFE, RELIES ON GETPWNAM, GETGRNAM
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* XXX USES *PW* AND *GR* WHICH ARE STATEFUL AND THEREFORE THIS ROUTINE
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* MAY HAVE SIDE-EFFECTS
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*
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* XXX currently doesn't deal correctly with a numeric uid being passed
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* instead of a username. What is correct behavior here? Check chown.
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*/
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int
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acl_name_to_id(acl_tag_t tag, char *name, uid_t *id)
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{
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struct group *g;
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struct passwd *p;
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switch(tag) {
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case ACL_USER:
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p = getpwnam(name);
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if (!p) {
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errno = EINVAL;
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return (-1);
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}
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*id = p->pw_uid;
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return (0);
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case ACL_GROUP:
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g = getgrnam(name);
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if (g) {
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errno = EINVAL;
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return (-1);
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}
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*id = g->gr_gid;
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return (0);
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default:
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return (EINVAL);
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}
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}
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/*
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* Given a right-shifted permission (i.e., direct ACL_PERM_* mask), fill
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* in a string describing the permissions.
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*/
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int
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acl_perm_to_string(acl_perm_t perm, ssize_t buf_len, char *buf)
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{
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if (buf_len < ACL_STRING_PERM_MAXSIZE + 1) {
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errno = ENOMEM;
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return (-1);
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}
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if ((perm | ACL_PERM_BITS) != ACL_PERM_BITS) {
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errno = EINVAL;
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return (-1);
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}
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buf[3] = 0; /* null terminate */
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if (perm & ACL_PERM_READ)
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buf[0] = ACL_STRING_PERM_READ;
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else
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buf[0] = ACL_STRING_PERM_NONE;
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if (perm & ACL_PERM_WRITE)
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buf[1] = ACL_STRING_PERM_WRITE;
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else
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buf[1] = ACL_STRING_PERM_NONE;
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if (perm & ACL_PERM_EXEC)
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buf[2] = ACL_STRING_PERM_EXEC;
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else
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buf[2] = ACL_STRING_PERM_NONE;
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return (0);
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}
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/*
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* given a string, return a permission describing it
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*/
|
||
|
|
int
|
||
|
|
acl_string_to_perm(char *string, acl_perm_t *perm)
|
||
|
|
{
|
||
|
|
acl_perm_t myperm = ACL_PERM_NONE;
|
||
|
|
char *ch;
|
||
|
|
|
||
|
|
ch = string;
|
||
|
|
while (*ch) {
|
||
|
|
switch(*ch) {
|
||
|
|
case ACL_STRING_PERM_READ:
|
||
|
|
myperm |= ACL_PERM_READ;
|
||
|
|
break;
|
||
|
|
case ACL_STRING_PERM_WRITE:
|
||
|
|
myperm |= ACL_PERM_WRITE;
|
||
|
|
break;
|
||
|
|
case ACL_STRING_PERM_EXEC:
|
||
|
|
myperm |= ACL_PERM_EXEC;
|
||
|
|
break;
|
||
|
|
case ACL_STRING_PERM_NONE:
|
||
|
|
break;
|
||
|
|
default:
|
||
|
|
return (EINVAL);
|
||
|
|
}
|
||
|
|
ch++;
|
||
|
|
}
|
||
|
|
|
||
|
|
*perm = myperm;
|
||
|
|
return (0);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Add an ACL entry without doing much checking, et al
|
||
|
|
*/
|
||
|
|
int
|
||
|
|
acl_add_entry(acl_t acl, acl_tag_t tag, uid_t id, acl_perm_t perm)
|
||
|
|
{
|
||
|
|
struct acl_entry *e;
|
||
|
|
|
||
|
|
if (acl->acl_cnt >= MAX_ACL_ENTRIES) {
|
||
|
|
errno = ENOMEM;
|
||
|
|
return (-1);
|
||
|
|
}
|
||
|
|
|
||
|
|
e = &(acl->acl_entry[acl->acl_cnt]);
|
||
|
|
e->ae_perm = perm;
|
||
|
|
e->ae_tag = tag;
|
||
|
|
e->ae_id = id;
|
||
|
|
acl->acl_cnt++;
|
||
|
|
|
||
|
|
return (0);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
|