xref: /illumos-gate/usr/src/uts/common/syscall/access.c (revision 6a634c9d)
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 
60 static int
caccess(char * fname,int fmode,vnode_t * startvp)61 caccess(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 
92 lookup:
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 
119 int
faccessat(int fd,char * fname,int fmode,int flag)120 faccessat(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 
148 int
access(char * fname,int fmode)149 access(char *fname, int fmode)
150 {
151 	return (faccessat(AT_FDCWD, fname, fmode, 0));
152 }
153