1 /* $NetBSD: chroot.c,v 1.19 2011/09/20 14:28:52 christos Exp $ */
2
3 /*
4 * Copyright (c) 1988, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 #ifndef lint
34 __COPYRIGHT("@(#) Copyright (c) 1988, 1993\
35 The Regents of the University of California. All rights reserved.");
36 #endif /* not lint */
37
38 #ifndef lint
39 #if 0
40 static char sccsid[] = "@(#)chroot.c 8.1 (Berkeley) 6/9/93";
41 #else
42 __RCSID("$NetBSD: chroot.c,v 1.19 2011/09/20 14:28:52 christos Exp $");
43 #endif
44 #endif /* not lint */
45
46 #include <sys/param.h>
47
48 #include <err.h>
49 #include <errno.h>
50 #include <grp.h>
51 #include <paths.h>
52 #include <pwd.h>
53 #include <stdio.h>
54 #include <stdlib.h>
55 #include <inttypes.h>
56 #include <string.h>
57 #include <unistd.h>
58
59 static void usage(void) __dead;
60
61 static int
getnum(const char * str,uintmax_t * num)62 getnum(const char *str, uintmax_t *num)
63 {
64 char *ep;
65
66 errno = 0;
67
68 *num = strtoumax(str, &ep, 0);
69 if (str[0] == '\0' || *ep != '\0') {
70 errno = EINVAL;
71 return -1;
72 }
73
74 if (errno == ERANGE && *num == UINTMAX_MAX)
75 return -1;
76
77 return 0;
78 }
79
80
81 static gid_t
getgroup(const char * group)82 getgroup(const char *group)
83 {
84 uintmax_t num;
85 struct group *gp;
86
87 if ((gp = getgrnam(group)) != NULL)
88 return gp->gr_gid;
89
90 if (getnum(group, &num) == -1)
91 errx(1, "no such group `%s'", group);
92
93 return (gid_t)num;
94 }
95
96 static uid_t
getuser(const char * user)97 getuser(const char *user)
98 {
99 uintmax_t num;
100 struct passwd *pw;
101
102 if ((pw = getpwnam(user)) != NULL)
103 return pw->pw_uid;
104
105 if (getnum(user, &num) == -1)
106 errx(1, "no such user `%s'", user);
107
108 return (uid_t)num;
109 }
110
111 int
main(int argc,char * argv[])112 main(int argc, char *argv[])
113 {
114 char *user; /* user to switch to before running program */
115 char *group; /* group to switch to ... */
116 char *grouplist; /* group list to switch to ... */
117 char *p;
118 const char *shell;
119 gid_t gid, gidlist[NGROUPS_MAX];
120 uid_t uid;
121 int ch, gids;
122
123 user = NULL;
124 group = NULL;
125 grouplist = NULL;
126 gid = 0;
127 uid = 0;
128 gids = 0;
129 while ((ch = getopt(argc, argv, "G:g:u:")) != -1) {
130 switch(ch) {
131 case 'u':
132 user = optarg;
133 if (*user == '\0')
134 usage();
135 break;
136 case 'g':
137 group = optarg;
138 if (*group == '\0')
139 usage();
140 break;
141 case 'G':
142 grouplist = optarg;
143 if (*grouplist == '\0')
144 usage();
145 break;
146 case '?':
147 default:
148 usage();
149 }
150 }
151 argc -= optind;
152 argv += optind;
153
154 if (argc < 1)
155 usage();
156
157 if (user != NULL)
158 uid = getuser(user);
159
160 if (group != NULL)
161 gid = getgroup(group);
162
163 if (grouplist != NULL) {
164 while ((p = strsep(&grouplist, ",")) != NULL) {
165 if (*p == '\0')
166 continue;
167
168 if (gids == NGROUPS_MAX)
169 errx(1,
170 "too many supplementary groups provided");
171
172 gidlist[gids++] = getgroup(p);
173 }
174 }
175
176 if (chdir(argv[0]) == -1 || chroot(".") == -1)
177 err(1, "%s", argv[0]);
178
179 if (gids && setgroups(gids, gidlist) == -1)
180 err(1, "setgroups");
181 if (group && setgid(gid) == -1)
182 err(1, "setgid");
183 if (user && setuid(uid) == -1)
184 err(1, "setuid");
185
186 if (argv[1]) {
187 execvp(argv[1], &argv[1]);
188 err(1, "%s", argv[1]);
189 }
190
191 if ((shell = getenv("SHELL")) == NULL)
192 shell = _PATH_BSHELL;
193 execlp(shell, shell, "-i", NULL);
194 err(1, "%s", shell);
195 /* NOTREACHED */
196 }
197
198 static void
usage(void)199 usage(void)
200 {
201
202 (void)fprintf(stderr, "Usage: %s [-G group,group,...] [-g group] "
203 "[-u user] newroot [command]\n", getprogname());
204 exit(1);
205 }
206