1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22/*
23 * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
24 */
25
26/*	Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T	*/
27/*	  All Rights Reserved  	*/
28
29/*
30 * Portions of this source code were derived from Berkeley 4.3 BSD
31 * under license from the Regents of the University of California.
32 */
33
34#include <sys/param.h>
35#include <sys/isa_defs.h>
36#include <sys/types.h>
37#include <sys/sysmacros.h>
38#include <sys/cred_impl.h>
39#include <sys/systm.h>
40#include <sys/errno.h>
41#include <sys/pathname.h>
42#include <sys/vnode.h>
43#include <sys/uio.h>
44#include <sys/cmn_err.h>
45#include <sys/debug.h>
46#include <sys/file.h>
47#include <fs/fs_subr.h>
48#include <c2/audit.h>
49#include <sys/fcntl.h>
50
51/*
52 * Determine accessibility of file.
53 */
54
55#define	E_OK	010	/* use effective ids */
56#define	R_OK	004
57#define	W_OK	002
58#define	X_OK	001
59
60static int
61caccess(char *fname, int fmode, vnode_t *startvp)
62{
63	vnode_t *vp;
64	cred_t *tmpcr;
65	int error;
66	int mode;
67	int eok;
68	cred_t *cr;
69	int estale_retry = 0;
70
71	if (fmode & ~(E_OK|R_OK|W_OK|X_OK))
72		return (EINVAL);
73
74	mode = ((fmode & (R_OK|W_OK|X_OK)) << 6);
75
76	cr = CRED();
77
78	/* OK to use effective uid/gid, i.e., no need to crdup(CRED())? */
79	eok = (fmode & E_OK) ||
80	    (cr->cr_uid == cr->cr_ruid && cr->cr_gid == cr->cr_rgid);
81
82	if (eok)
83		tmpcr = cr;
84	else {
85		tmpcr = crdup(cr);
86		tmpcr->cr_uid = cr->cr_ruid;
87		tmpcr->cr_gid = cr->cr_rgid;
88		tmpcr->cr_ruid = cr->cr_uid;
89		tmpcr->cr_rgid = cr->cr_gid;
90	}
91
92lookup:
93	if (error = lookupnameatcred(fname, UIO_USERSPACE, FOLLOW, NULLVPP, &vp,
94	    startvp, tmpcr)) {
95		if ((error == ESTALE) && fs_need_estale_retry(estale_retry++))
96			goto lookup;
97		if (!eok)
98			crfree(tmpcr);
99		return (error);
100	}
101
102	if (mode) {
103		error = VOP_ACCESS(vp, mode, 0, tmpcr, NULL);
104		if (error) {
105			if ((error == ESTALE) &&
106			    fs_need_estale_retry(estale_retry++)) {
107				VN_RELE(vp);
108				goto lookup;
109			}
110		}
111	}
112
113	if (!eok)
114		crfree(tmpcr);
115	VN_RELE(vp);
116	return (error);
117}
118
119int
120faccessat(int fd, char *fname, int fmode, int flag)
121{
122	vnode_t *startvp;
123	int error;
124
125	if ((flag & ~AT_EACCESS) != 0)
126		return (set_errno(EINVAL));
127
128	if (fname == NULL)
129		return (set_errno(EFAULT));
130	if ((error = fgetstartvp(fd, fname, &startvp)) != 0)
131		return (set_errno(error));
132	if (AU_AUDITING() && startvp != NULL)
133		audit_setfsat_path(1);
134
135	/* Do not allow E_OK unless AT_EACCESS flag is set */
136	fmode &= ~E_OK;
137	if (flag & AT_EACCESS)
138		fmode |= E_OK;
139
140	error = caccess(fname, fmode, startvp);
141	if (startvp != NULL)
142		VN_RELE(startvp);
143	if (error)
144		return (set_errno(error));
145	return (0);
146}
147
148int
149access(char *fname, int fmode)
150{
151	return (faccessat(AT_FDCWD, fname, fmode, 0));
152}
153