Annotation of src/usr.bin/su/su.c, Revision 1.44
1.44 ! millert 1: /* $OpenBSD: su.c,v 1.43 2002/02/16 21:27:54 millert Exp $ */
1.4 deraadt 2:
1.1 deraadt 3: /*
4: * Copyright (c) 1988 The Regents of the University of California.
5: * 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. All advertising materials mentioning features or use of this software
16: * must display the following acknowledgement:
17: * This product includes software developed by the University of
18: * California, Berkeley and its contributors.
19: * 4. Neither the name of the University nor the names of its contributors
20: * may be used to endorse or promote products derived from this software
21: * without specific prior written permission.
22: *
23: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33: * SUCH DAMAGE.
34: */
35:
36: #ifndef lint
1.41 millert 37: static const char copyright[] =
1.1 deraadt 38: "@(#) Copyright (c) 1988 The Regents of the University of California.\n\
39: All rights reserved.\n";
40: #endif /* not lint */
41:
42: #ifndef lint
1.41 millert 43: #if 0
44: static const char sccsid[] = "from: @(#)su.c 5.26 (Berkeley) 7/6/91";
45: #else
1.44 ! millert 46: static const char rcsid[] = "$OpenBSD: su.c,v 1.43 2002/02/16 21:27:54 millert Exp $";
1.41 millert 47: #endif
1.1 deraadt 48: #endif /* not lint */
49:
50: #include <sys/param.h>
51: #include <sys/time.h>
52: #include <sys/resource.h>
1.8 millert 53:
54: #include <err.h>
55: #include <errno.h>
56: #include <grp.h>
1.33 millert 57: #include <login_cap.h>
1.8 millert 58: #include <paths.h>
59: #include <pwd.h>
1.1 deraadt 60: #include <stdio.h>
61: #include <stdlib.h>
62: #include <string.h>
1.8 millert 63: #include <syslog.h>
1.1 deraadt 64: #include <unistd.h>
1.36 millert 65: #include <stdarg.h>
66: #include <bsd_auth.h>
67:
1.43 millert 68: char *ontty(void);
69: int chshell(char *);
70: void usage(void);
71: void auth_err(auth_session_t *, int, const char *, ...);
72: void auth_errx(auth_session_t *, int, const char *, ...);
1.1 deraadt 73:
74: int
75: main(argc, argv)
76: int argc;
77: char **argv;
78: {
79: extern char **environ;
1.36 millert 80: enum { UNSET, YES, NO } iscsh;
81: struct passwd *pwd;
1.1 deraadt 82: struct group *gr;
1.9 millert 83: uid_t ruid;
1.33 millert 84: login_cap_t *lc;
1.36 millert 85: auth_session_t *as;
86: int asme, asthem, authok, ch, fastlogin, prio;
87: char *class, *style, *p, **g;
88: char *user, *shell, *avshell, *username, **np, *fullname;
1.41 millert 89: char avshellbuf[MAXPATHLEN];
1.1 deraadt 90:
1.33 millert 91: iscsh = UNSET;
1.36 millert 92: class = shell = style = NULL;
1.1 deraadt 93: asme = asthem = fastlogin = 0;
1.37 millert 94: while ((ch = getopt(argc, argv, "-a:c:fKlm")) != -1)
1.36 millert 95: switch(ch) {
96: case 'a':
97: if (style)
98: usage();
99: style = optarg;
1.1 deraadt 100: break;
1.33 millert 101: case 'c':
1.36 millert 102: if (class)
103: usage();
1.33 millert 104: class = optarg;
105: break;
1.1 deraadt 106: case 'f':
107: fastlogin = 1;
108: break;
1.36 millert 109: case 'K':
110: if (style)
111: usage();
112: style = "passwd";
113: break;
1.1 deraadt 114: case '-':
115: case 'l':
116: asme = 0;
117: asthem = 1;
118: break;
119: case 'm':
120: asme = 1;
121: asthem = 0;
122: break;
123: case '?':
124: default:
1.36 millert 125: usage();
1.1 deraadt 126: }
127: argv += optind;
128:
129: errno = 0;
130: prio = getpriority(PRIO_PROCESS, 0);
131: if (errno)
132: prio = 0;
133: (void)setpriority(PRIO_PROCESS, 0, -2);
134: openlog("su", LOG_CONS, 0);
135:
1.36 millert 136: if ((as = auth_open()) == NULL) {
137: syslog(LOG_ERR, "auth_open: %m");
1.39 millert 138: err(1, "unable to initialize BSD authentication");
1.36 millert 139: }
1.39 millert 140: auth_setoption(as, "login", "yes");
1.36 millert 141:
1.1 deraadt 142: /* get current login name and shell */
143: ruid = getuid();
144: username = getlogin();
1.40 hin 145:
1.41 millert 146: if (username != NULL)
1.40 hin 147: auth_setoption(as, "invokinguser", username);
148:
1.1 deraadt 149: if (username == NULL || (pwd = getpwnam(username)) == NULL ||
150: pwd->pw_uid != ruid)
151: pwd = getpwuid(ruid);
1.8 millert 152: if (pwd == NULL)
1.36 millert 153: auth_errx(as, 1, "who are you?");
1.9 millert 154: if ((username = strdup(pwd->pw_name)) == NULL)
1.41 millert 155: auth_errx(as, 1, "can't allocate memory");
1.31 art 156: if (asme) {
1.10 millert 157: if (pwd->pw_shell && *pwd->pw_shell) {
1.42 millert 158: if ((shell = strdup(pwd->pw_shell)) == NULL)
159: auth_errx(as, 1, "can't allocate memory");
1.10 millert 160: } else {
1.1 deraadt 161: shell = _PATH_BSHELL;
162: iscsh = NO;
163: }
1.31 art 164: }
1.1 deraadt 165:
166: /* get target login information, default to root */
167: user = *argv ? *argv : "root";
1.36 millert 168: np = *argv ? argv : argv - 1;
1.1 deraadt 169:
1.8 millert 170: if ((pwd = getpwnam(user)) == NULL)
1.36 millert 171: auth_errx(as, 1, "unknown login %s", user);
1.41 millert 172: if ((pwd = pw_dup(pwd)) == NULL)
173: auth_errx(as, 1, "can't allocate memory");
174: user = pwd->pw_name;
1.1 deraadt 175:
1.33 millert 176: /* If the user specified a login class and we are root, use it */
177: if (ruid && class)
1.36 millert 178: auth_errx(as, 1, "only the superuser may specify a login class");
1.33 millert 179: if (class)
180: pwd->pw_class = class;
181: if ((lc = login_getclass(pwd->pw_class)) == NULL)
1.36 millert 182: auth_errx(as, 1, "no such login class: %s",
1.33 millert 183: class ? class : LOGIN_DEFCLASS);
184:
1.1 deraadt 185: if (ruid) {
1.36 millert 186: /*
187: * If we are trying to become root and the default style
188: * is being used, don't bother to look it up (we might be
189: * be su'ing up to fix /etc/login.conf)
190: */
191: if ((pwd->pw_uid || !style || strcmp(style, LOGIN_DEFSTYLE)) &&
192: (style = login_getstyle(lc, style, "auth-su")) == NULL)
193: auth_errx(as, 1, "invalid authentication type");
1.40 hin 194: fullname = user;
1.36 millert 195: /*
196: * Let the authentication program know whether they are
197: * in group wheel or not (if trying to become super user)
198: */
1.3 deraadt 199: if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0))
1.36 millert 200: && gr->gr_mem && *(gr->gr_mem)) {
201: for (g = gr->gr_mem; *g; ++g) {
202: if (strcmp(username, *g) == 0) {
203: auth_setoption(as, "wheel", "yes");
1.1 deraadt 204: break;
1.36 millert 205: }
206: }
207: if (!*g)
208: auth_setoption(as, "wheel", "no");
1.1 deraadt 209: }
1.36 millert 210:
211: auth_verify(as, style, fullname, lc->lc_class, NULL);
212: authok = auth_getstate(as);
213: if ((authok & AUTH_ALLOW) == 0) {
214: if ((p = auth_getvalue(as, "errormsg")) != NULL)
215: fprintf(stderr, "%s\n", p);
216: fprintf(stderr, "Sorry\n");
217: syslog(LOG_AUTH|LOG_WARNING,
218: "BAD SU %s to %s%s", username, user, ontty());
219: auth_close(as);
220: exit(1);
1.1 deraadt 221: }
222: }
223:
224: if (asme) {
225: /* if asme and non-standard target shell, must be root */
1.8 millert 226: if (!chshell(pwd->pw_shell) && ruid)
1.36 millert 227: auth_errx(as, 1, "permission denied (shell).");
1.1 deraadt 228: } else if (pwd->pw_shell && *pwd->pw_shell) {
229: shell = pwd->pw_shell;
230: iscsh = UNSET;
231: } else {
232: shell = _PATH_BSHELL;
233: iscsh = NO;
234: }
235:
1.30 deraadt 236: if ((p = strrchr(shell, '/')))
1.1 deraadt 237: avshell = p+1;
238: else
239: avshell = shell;
240:
241: /* if we're forking a csh, we want to slightly muck the args */
242: if (iscsh == UNSET)
243: iscsh = strcmp(avshell, "csh") ? NO : YES;
244:
245: if (!asme) {
246: if (asthem) {
247: p = getenv("TERM");
1.23 deraadt 248: if ((environ = calloc(1, sizeof (char *))) == NULL)
1.36 millert 249: auth_errx(as, 1, "calloc");
1.33 millert 250: if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETPATH))
1.36 millert 251: auth_err(as, 1, "unable to set user context");
252: if (p && setenv("TERM", p, 1) == -1)
253: auth_err(as, 1, "unable to set environment");
1.5 deraadt 254:
255: seteuid(pwd->pw_uid);
256: setegid(pwd->pw_gid);
1.8 millert 257: if (chdir(pwd->pw_dir) < 0)
1.36 millert 258: auth_err(as, 1, "%s", pwd->pw_dir);
1.5 deraadt 259: seteuid(0);
260: setegid(0); /* XXX use a saved gid instead? */
1.33 millert 261: } else if (pwd->pw_uid == 0) {
262: if (setusercontext(lc,
263: pwd, pwd->pw_uid, LOGIN_SETPATH|LOGIN_SETUMASK))
1.36 millert 264: auth_err(as, 1, "unable to set user context");
1.1 deraadt 265: }
1.15 millert 266: if (asthem || pwd->pw_uid) {
1.34 deraadt 267: if (setenv("LOGNAME", pwd->pw_name, 1) == -1 ||
268: setenv("USER", pwd->pw_name, 1) == -1)
1.36 millert 269: auth_err(as, 1, "unable to set environment");
1.15 millert 270: }
1.34 deraadt 271: if (setenv("HOME", pwd->pw_dir, 1) == -1 ||
272: setenv("SHELL", shell, 1) == -1)
1.36 millert 273: auth_err(as, 1, "unable to set environment");
1.34 deraadt 274: }
1.28 deraadt 275:
1.1 deraadt 276: if (iscsh == YES) {
277: if (fastlogin)
278: *np-- = "-f";
279: if (asme)
280: *np-- = "-m";
281: }
282:
283: if (asthem) {
284: avshellbuf[0] = '-';
1.36 millert 285: strlcpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 1);
1.1 deraadt 286: avshell = avshellbuf;
287: } else if (iscsh == YES) {
288: /* csh strips the first character... */
289: avshellbuf[0] = '_';
1.36 millert 290: strlcpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 1);
1.1 deraadt 291: avshell = avshellbuf;
292: }
293:
294: *np = avshell;
295:
296: if (ruid != 0)
297: syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s",
298: username, user, ontty());
299:
300: (void)setpriority(PRIO_PROCESS, 0, prio);
1.33 millert 301: if (setusercontext(lc, pwd, pwd->pw_uid,
302: (asthem ? (LOGIN_SETPRIORITY | LOGIN_SETUMASK) : 0) |
303: LOGIN_SETRESOURCES | LOGIN_SETGROUP | LOGIN_SETUSER))
1.36 millert 304: auth_err(as, 1, "unable to set user context");
305: if (pwd->pw_uid && auth_approval(as, lc, pwd->pw_name, "su") <= 0)
306: auth_err(as, 1, "approval failure");
307: auth_close(as);
1.1 deraadt 308:
309: execv(shell, np);
1.32 millert 310: err(1, "%s", shell);
1.1 deraadt 311: }
312:
313: int
314: chshell(sh)
315: char *sh;
316: {
1.36 millert 317: char *cp;
1.1 deraadt 318:
319: while ((cp = getusershell()) != NULL)
1.8 millert 320: if (strcmp(cp, sh) == 0)
1.1 deraadt 321: return (1);
322: return (0);
323: }
324:
325: char *
326: ontty()
327: {
328: static char buf[MAXPATHLEN + 4];
1.36 millert 329: char *p;
1.1 deraadt 330:
331: buf[0] = 0;
1.30 deraadt 332: if ((p = ttyname(STDERR_FILENO)))
1.8 millert 333: snprintf(buf, sizeof(buf), " on %s", p);
1.1 deraadt 334: return (buf);
335: }
336:
1.36 millert 337: void
338: usage()
1.1 deraadt 339: {
1.36 millert 340: extern char *__progname;
1.1 deraadt 341:
1.37 millert 342: fprintf(stderr, "usage: %s [-fKlm] [-a auth-type] %s ", __progname,
1.38 millert 343: "[-c login-class] [login [shell arguments]]\n");
1.36 millert 344: exit(1);
1.1 deraadt 345: }
346:
1.36 millert 347: void
348: auth_err(auth_session_t *as, int eval, const char *fmt, ...)
1.1 deraadt 349: {
1.36 millert 350: va_list ap;
351: va_start(ap, fmt);
352: verr(eval, fmt, ap);
353: auth_close(as);
354: va_end(ap);
1.28 deraadt 355: }
356:
1.36 millert 357: void
358: auth_errx(auth_session_t *as, int eval, const char *fmt, ...)
1.28 deraadt 359: {
1.36 millert 360: va_list ap;
361: va_start(ap, fmt);
362: verrx(eval, fmt, ap);
363: auth_close(as);
364: va_end(ap);
1.1 deraadt 365: }
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