Replace all casts of NULL to something with NULL.
[dragonfly.git] / usr.bin / newgrp / newgrp.c
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1/*-
2 * Copyright (c) 2002 Tim J. Robbins.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: /src/usr.bin/newgrp/newgrp.c,v 1.2 2003/10/30 15:14:34 harti Exp $
9acc8450 27 * $DragonFly: src/usr.bin/newgrp/newgrp.c,v 1.3 2004/12/08 22:26:42 liamfoy Exp $
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28 */
29
30/*
31 * newgrp -- change to a new group
32 */
33
34#include <sys/types.h>
35
36#include <err.h>
37#include <errno.h>
38#include <grp.h>
39#include <libgen.h>
40#include <limits.h>
41#include <login_cap.h>
42#include <paths.h>
43#include <pwd.h>
44#include <stdio.h>
45#include <stdlib.h>
46#include <string.h>
47#include <unistd.h>
48
49static void addgroup(const char *grpname);
50static void doshell(void);
51static int inarray(gid_t, const gid_t[], int);
52static void loginshell(void);
53static void restoregrps(void);
54static void usage(void);
55
56static struct passwd *pwd;
57static uid_t euid;
58
59extern char **environ;
60
61/* Manipulate effective user ID. */
62#define PRIV_START do { \
63 if (seteuid(euid) < 0) \
64 err(1, "seteuid"); \
65 } while (0)
66#define PRIV_END do { \
67 if (seteuid(getuid()) < 0) \
68 err(1, "seteuid"); \
69 } while (0)
70
71int
72main(int argc, char *argv[])
73{
74 int ch, login;
75
76 euid = geteuid();
77 if (seteuid(getuid()) < 0)
78 err(1, "seteuid");
79
80 if ((pwd = getpwuid(getuid())) == NULL)
81 errx(1, "unknown user");
82
83 login = 0;
84 while ((ch = getopt(argc, argv, "-l")) != -1) {
85 switch (ch) {
86 case '-': /* Obsolescent */
87 case 'l':
88 login = 1;
89 break;
90 default:
91 usage();
92 }
93 }
94 argc -= optind;
95 argv += optind;
96
97 switch (argc) {
98 case 0:
99 restoregrps();
100 break;
101 case 1:
102 addgroup(*argv);
103 break;
104 default:
105 usage();
106 }
107
108 if (seteuid(euid) < 0)
109 err(1, "seteuid");
110 if (setuid(getuid()) < 0)
111 err(1, "setuid");
112
113 if (login)
114 loginshell();
115 else
116 doshell();
117
118 /*NOTREACHED*/
119 exit(1);
120}
121
122static void
123usage(void)
124{
125
126 fprintf(stderr, "usage: newgrp [-l] [group]\n");
127 exit(1);
128}
129
130static void
131restoregrps(void)
132{
133 int initres, setres;
134
135 PRIV_START;
136 initres = initgroups(pwd->pw_name, pwd->pw_gid);
137 setres = setgid(pwd->pw_gid);
138 PRIV_END;
139
140 if (initres < 0)
141 warn("initgroups");
142 if (setres < 0)
143 warn("setgroups");
144}
145
146static void
147addgroup(const char *grpname)
148{
149 gid_t grps[NGROUPS_MAX];
150 long lgid;
151 int dbmember, i, ngrps;
152 gid_t egid;
153 struct group *grp;
154 char *ep, *pass;
155 char **p;
156
157 egid = getegid();
158
159 /* Try it as a group name, then a group id. */
160 if ((grp = getgrnam(grpname)) == NULL)
161 if ((lgid = strtol(grpname, &ep, 10)) <= 0 || *ep != '\0' ||
162 (grp = getgrgid((gid_t)lgid)) == NULL ) {
163 warnx("%s: bad group name", grpname);
164 return;
165 }
166
167 /*
168 * If the user is not a member of the requested group and the group
169 * has a password, prompt and check it.
170 */
171 dbmember = 0;
172 if (pwd->pw_gid == grp->gr_gid)
173 dbmember = 1;
174 for (p = grp->gr_mem; *p != NULL; p++)
175 if (strcmp(*p, pwd->pw_name) == 0) {
176 dbmember = 1;
177 break;
178 }
179 if (!dbmember && *grp->gr_passwd != '\0' && getuid() != 0) {
180 pass = getpass("Password:");
181 if (pass == NULL ||
182 strcmp(grp->gr_passwd, crypt(pass, grp->gr_passwd)) != 0) {
183 fprintf(stderr, "Sorry\n");
184 return;
185 }
186 }
187
188 if ((ngrps = getgroups(NGROUPS_MAX, (gid_t *)grps)) < 0) {
189 warn("getgroups");
190 return;
191 }
192
193 /* Remove requested gid from supp. list if it exists. */
194 if (grp->gr_gid != egid && inarray(grp->gr_gid, grps, ngrps)) {
195 for (i = 0; i < ngrps; i++)
196 if (grps[i] == grp->gr_gid)
197 break;
198 ngrps--;
199 memmove(&grps[i], &grps[i + 1], (ngrps - i) * sizeof(gid_t));
200 PRIV_START;
201 if (setgroups(ngrps, (const gid_t *)grps) < 0) {
202 PRIV_END;
203 warn("setgroups");
204 return;
205 }
206 PRIV_END;
207 }
208
209 PRIV_START;
210 if (setgid(grp->gr_gid)) {
211 PRIV_END;
212 warn("setgid");
213 return;
214 }
215 PRIV_END;
216 grps[0] = grp->gr_gid;
217
218 /* Add old effective gid to supp. list if it does not exist. */
219 if (egid != grp->gr_gid && !inarray(egid, grps, ngrps)) {
220 if (ngrps == NGROUPS_MAX)
221 warnx("too many groups");
222 else {
223 grps[ngrps++] = egid;
224 PRIV_START;
225 if (setgroups(ngrps, (const gid_t *)grps)) {
226 PRIV_END;
227 warn("setgroups");
228 return;
229 }
230 PRIV_END;
231 }
232 }
233
234}
235
236static int
237inarray(gid_t gid, const gid_t grps[], int ngrps)
238{
239 int i;
240
241 for (i = 0; i < ngrps; i++)
242 if (grps[i] == gid)
243 return (1);
244 return (0);
245}
246
247/*
248 * Set the environment to what would be expected if the user logged in
249 * again; this performs the same steps as su(1)'s -l option.
250 */
251static void
252loginshell(void)
253{
254 char *args[2], **cleanenv, *term, *ticket;
255 const char *shell;
256 login_cap_t *lc;
257
258 shell = pwd->pw_shell;
259 if (*shell == '\0')
260 shell = _PATH_BSHELL;
261 if (chdir(pwd->pw_dir) < 0) {
262 warn("%s", pwd->pw_dir);
263 chdir("/");
264 }
265
266 term = getenv("TERM");
267 ticket = getenv("KRBTKFILE");
268
269 if ((cleanenv = calloc(20, sizeof(char *))) == NULL)
270 err(1, "calloc");
271 *cleanenv = NULL;
272 environ = cleanenv;
273
274 lc = login_getpwclass(pwd);
275 setusercontext(lc, pwd, pwd->pw_uid,
276 LOGIN_SETPATH|LOGIN_SETUMASK|LOGIN_SETENV);
277 login_close(lc);
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278 if (setenv("USER", pwd->pw_name, 1) == -1)
279 err(EXIT_FAILURE, "setenv failed");
280
281 if (setenv("SHELL", shell, 1) == -1)
282 err(EXIT_FAILURE, "setenv failed");
283
284 if (setenv("HOME", pwd->pw_dir, 1) == -1)
285 err(EXIT_FAILURE, "setenv failed");
286
333227be 287 if (term != NULL)
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288 if (setenv("TERM", term, 1) == -1)
289 err(EXIT_FAILURE, "setenv failed");
333227be 290 if (ticket != NULL)
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291 if (setenv("KRBTKFILE", ticket, 1) == -1)
292 err(EXIT_FAILURE, "setenv failed");
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293
294 if (asprintf(args, "-%s", basename(shell)) < 0)
295 err(1, "asprintf");
296 args[1] = NULL;
297
298 execv(shell, args);
299 err(1, "%s", shell);
300}
301
302static void
303doshell(void)
304{
305 const char *shell;
306
307 shell = pwd->pw_shell;
308 if (*shell == '\0')
309 shell = _PATH_BSHELL;
2038fb68 310 execl(shell, basename(shell), NULL);
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311 err(1, "%s", shell);
312}