Annotation of src/usr.bin/su/su.c, Revision 1.42
1.42 ! millert 1: /* $OpenBSD: su.c,v 1.41 2001/09/18 04:41:09 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
1.42 ! millert 46: static const char rcsid[] = "$OpenBSD: su.c,v 1.41 2001/09/18 04:41:09 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: #ifdef __STDC__
66: #include <stdarg.h>
1.1 deraadt 67: #else
1.36 millert 68: #include <varargs.h>
1.1 deraadt 69: #endif
1.36 millert 70: #include <bsd_auth.h>
71:
1.8 millert 72: char *ontty __P((void));
73: int chshell __P((char *));
1.36 millert 74: void usage __P((void));
75: void auth_err __P((auth_session_t *, int, const char *, ...));
76: void auth_errx __P((auth_session_t *, int, const char *, ...));
1.1 deraadt 77:
78: int
79: main(argc, argv)
80: int argc;
81: char **argv;
82: {
83: extern char **environ;
1.36 millert 84: enum { UNSET, YES, NO } iscsh;
85: struct passwd *pwd;
1.1 deraadt 86: struct group *gr;
1.9 millert 87: uid_t ruid;
1.33 millert 88: login_cap_t *lc;
1.36 millert 89: auth_session_t *as;
90: int asme, asthem, authok, ch, fastlogin, prio;
91: char *class, *style, *p, **g;
92: char *user, *shell, *avshell, *username, **np, *fullname;
1.41 millert 93: char avshellbuf[MAXPATHLEN];
1.1 deraadt 94:
1.33 millert 95: iscsh = UNSET;
1.36 millert 96: class = shell = style = NULL;
1.1 deraadt 97: asme = asthem = fastlogin = 0;
1.37 millert 98: while ((ch = getopt(argc, argv, "-a:c:fKlm")) != -1)
1.36 millert 99: switch(ch) {
100: case 'a':
101: if (style)
102: usage();
103: style = optarg;
1.1 deraadt 104: break;
1.33 millert 105: case 'c':
1.36 millert 106: if (class)
107: usage();
1.33 millert 108: class = optarg;
109: break;
1.1 deraadt 110: case 'f':
111: fastlogin = 1;
112: break;
1.36 millert 113: case 'K':
114: if (style)
115: usage();
116: style = "passwd";
117: break;
1.1 deraadt 118: case '-':
119: case 'l':
120: asme = 0;
121: asthem = 1;
122: break;
123: case 'm':
124: asme = 1;
125: asthem = 0;
126: break;
127: case '?':
128: default:
1.36 millert 129: usage();
1.1 deraadt 130: }
131: argv += optind;
132:
133: errno = 0;
134: prio = getpriority(PRIO_PROCESS, 0);
135: if (errno)
136: prio = 0;
137: (void)setpriority(PRIO_PROCESS, 0, -2);
138: openlog("su", LOG_CONS, 0);
139:
1.36 millert 140: if ((as = auth_open()) == NULL) {
141: syslog(LOG_ERR, "auth_open: %m");
1.39 millert 142: err(1, "unable to initialize BSD authentication");
1.36 millert 143: }
1.39 millert 144: auth_setoption(as, "login", "yes");
1.36 millert 145:
1.1 deraadt 146: /* get current login name and shell */
147: ruid = getuid();
148: username = getlogin();
1.40 hin 149:
1.41 millert 150: if (username != NULL)
1.40 hin 151: auth_setoption(as, "invokinguser", username);
152:
1.1 deraadt 153: if (username == NULL || (pwd = getpwnam(username)) == NULL ||
154: pwd->pw_uid != ruid)
155: pwd = getpwuid(ruid);
1.8 millert 156: if (pwd == NULL)
1.36 millert 157: auth_errx(as, 1, "who are you?");
1.9 millert 158: if ((username = strdup(pwd->pw_name)) == NULL)
1.41 millert 159: auth_errx(as, 1, "can't allocate memory");
1.31 art 160: if (asme) {
1.10 millert 161: if (pwd->pw_shell && *pwd->pw_shell) {
1.42 ! millert 162: if ((shell = strdup(pwd->pw_shell)) == NULL)
! 163: auth_errx(as, 1, "can't allocate memory");
1.10 millert 164: } else {
1.1 deraadt 165: shell = _PATH_BSHELL;
166: iscsh = NO;
167: }
1.31 art 168: }
1.1 deraadt 169:
170: /* get target login information, default to root */
171: user = *argv ? *argv : "root";
1.36 millert 172: np = *argv ? argv : argv - 1;
1.1 deraadt 173:
1.8 millert 174: if ((pwd = getpwnam(user)) == NULL)
1.36 millert 175: auth_errx(as, 1, "unknown login %s", user);
1.41 millert 176: if ((pwd = pw_dup(pwd)) == NULL)
177: auth_errx(as, 1, "can't allocate memory");
178: user = pwd->pw_name;
1.1 deraadt 179:
1.33 millert 180: /* If the user specified a login class and we are root, use it */
181: if (ruid && class)
1.36 millert 182: auth_errx(as, 1, "only the superuser may specify a login class");
1.33 millert 183: if (class)
184: pwd->pw_class = class;
185: if ((lc = login_getclass(pwd->pw_class)) == NULL)
1.36 millert 186: auth_errx(as, 1, "no such login class: %s",
1.33 millert 187: class ? class : LOGIN_DEFCLASS);
188:
1.1 deraadt 189: if (ruid) {
1.36 millert 190: /*
191: * If we are trying to become root and the default style
192: * is being used, don't bother to look it up (we might be
193: * be su'ing up to fix /etc/login.conf)
194: */
195: if ((pwd->pw_uid || !style || strcmp(style, LOGIN_DEFSTYLE)) &&
196: (style = login_getstyle(lc, style, "auth-su")) == NULL)
197: auth_errx(as, 1, "invalid authentication type");
1.40 hin 198: fullname = user;
1.36 millert 199: /*
200: * Let the authentication program know whether they are
201: * in group wheel or not (if trying to become super user)
202: */
1.3 deraadt 203: if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0))
1.36 millert 204: && gr->gr_mem && *(gr->gr_mem)) {
205: for (g = gr->gr_mem; *g; ++g) {
206: if (strcmp(username, *g) == 0) {
207: auth_setoption(as, "wheel", "yes");
1.1 deraadt 208: break;
1.36 millert 209: }
210: }
211: if (!*g)
212: auth_setoption(as, "wheel", "no");
1.1 deraadt 213: }
1.36 millert 214:
215: auth_verify(as, style, fullname, lc->lc_class, NULL);
216: authok = auth_getstate(as);
217: if ((authok & AUTH_ALLOW) == 0) {
218: if ((p = auth_getvalue(as, "errormsg")) != NULL)
219: fprintf(stderr, "%s\n", p);
220: fprintf(stderr, "Sorry\n");
221: syslog(LOG_AUTH|LOG_WARNING,
222: "BAD SU %s to %s%s", username, user, ontty());
223: auth_close(as);
224: exit(1);
1.1 deraadt 225: }
226: }
227:
228: if (asme) {
229: /* if asme and non-standard target shell, must be root */
1.8 millert 230: if (!chshell(pwd->pw_shell) && ruid)
1.36 millert 231: auth_errx(as, 1, "permission denied (shell).");
1.1 deraadt 232: } else if (pwd->pw_shell && *pwd->pw_shell) {
233: shell = pwd->pw_shell;
234: iscsh = UNSET;
235: } else {
236: shell = _PATH_BSHELL;
237: iscsh = NO;
238: }
239:
1.30 deraadt 240: if ((p = strrchr(shell, '/')))
1.1 deraadt 241: avshell = p+1;
242: else
243: avshell = shell;
244:
245: /* if we're forking a csh, we want to slightly muck the args */
246: if (iscsh == UNSET)
247: iscsh = strcmp(avshell, "csh") ? NO : YES;
248:
249: if (!asme) {
250: if (asthem) {
251: p = getenv("TERM");
1.23 deraadt 252: if ((environ = calloc(1, sizeof (char *))) == NULL)
1.36 millert 253: auth_errx(as, 1, "calloc");
1.33 millert 254: if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETPATH))
1.36 millert 255: auth_err(as, 1, "unable to set user context");
256: if (p && setenv("TERM", p, 1) == -1)
257: auth_err(as, 1, "unable to set environment");
1.5 deraadt 258:
259: seteuid(pwd->pw_uid);
260: setegid(pwd->pw_gid);
1.8 millert 261: if (chdir(pwd->pw_dir) < 0)
1.36 millert 262: auth_err(as, 1, "%s", pwd->pw_dir);
1.5 deraadt 263: seteuid(0);
264: setegid(0); /* XXX use a saved gid instead? */
1.33 millert 265: } else if (pwd->pw_uid == 0) {
266: if (setusercontext(lc,
267: pwd, pwd->pw_uid, LOGIN_SETPATH|LOGIN_SETUMASK))
1.36 millert 268: auth_err(as, 1, "unable to set user context");
1.1 deraadt 269: }
1.15 millert 270: if (asthem || pwd->pw_uid) {
1.34 deraadt 271: if (setenv("LOGNAME", pwd->pw_name, 1) == -1 ||
272: setenv("USER", pwd->pw_name, 1) == -1)
1.36 millert 273: auth_err(as, 1, "unable to set environment");
1.15 millert 274: }
1.34 deraadt 275: if (setenv("HOME", pwd->pw_dir, 1) == -1 ||
276: setenv("SHELL", shell, 1) == -1)
1.36 millert 277: auth_err(as, 1, "unable to set environment");
1.34 deraadt 278: }
1.28 deraadt 279:
1.1 deraadt 280: if (iscsh == YES) {
281: if (fastlogin)
282: *np-- = "-f";
283: if (asme)
284: *np-- = "-m";
285: }
286:
287: if (asthem) {
288: avshellbuf[0] = '-';
1.36 millert 289: strlcpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 1);
1.1 deraadt 290: avshell = avshellbuf;
291: } else if (iscsh == YES) {
292: /* csh strips the first character... */
293: avshellbuf[0] = '_';
1.36 millert 294: strlcpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 1);
1.1 deraadt 295: avshell = avshellbuf;
296: }
297:
298: *np = avshell;
299:
300: if (ruid != 0)
301: syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s",
302: username, user, ontty());
303:
304: (void)setpriority(PRIO_PROCESS, 0, prio);
1.33 millert 305: if (setusercontext(lc, pwd, pwd->pw_uid,
306: (asthem ? (LOGIN_SETPRIORITY | LOGIN_SETUMASK) : 0) |
307: LOGIN_SETRESOURCES | LOGIN_SETGROUP | LOGIN_SETUSER))
1.36 millert 308: auth_err(as, 1, "unable to set user context");
309: if (pwd->pw_uid && auth_approval(as, lc, pwd->pw_name, "su") <= 0)
310: auth_err(as, 1, "approval failure");
311: auth_close(as);
1.1 deraadt 312:
313: execv(shell, np);
1.32 millert 314: err(1, "%s", shell);
1.1 deraadt 315: }
316:
317: int
318: chshell(sh)
319: char *sh;
320: {
1.36 millert 321: char *cp;
1.1 deraadt 322:
323: while ((cp = getusershell()) != NULL)
1.8 millert 324: if (strcmp(cp, sh) == 0)
1.1 deraadt 325: return (1);
326: return (0);
327: }
328:
329: char *
330: ontty()
331: {
332: static char buf[MAXPATHLEN + 4];
1.36 millert 333: char *p;
1.1 deraadt 334:
335: buf[0] = 0;
1.30 deraadt 336: if ((p = ttyname(STDERR_FILENO)))
1.8 millert 337: snprintf(buf, sizeof(buf), " on %s", p);
1.1 deraadt 338: return (buf);
339: }
340:
1.36 millert 341: void
342: usage()
1.1 deraadt 343: {
1.36 millert 344: extern char *__progname;
1.1 deraadt 345:
1.37 millert 346: fprintf(stderr, "usage: %s [-fKlm] [-a auth-type] %s ", __progname,
1.38 millert 347: "[-c login-class] [login [shell arguments]]\n");
1.36 millert 348: exit(1);
1.1 deraadt 349: }
350:
1.36 millert 351: void
352: #ifdef __STDC__
353: auth_err(auth_session_t *as, int eval, const char *fmt, ...)
354: #else
355: auth_err(va_alist)
356: va_dcl
357: #endif
1.1 deraadt 358: {
1.36 millert 359: va_list ap;
360: #ifdef __STDC__
361: va_start(ap, fmt);
362: #else
363: auth_session_t *as;
364: int eval;
365: const char *fmt;
366:
367: va_start(ap);
368: as = va_arg(ap, auth_session_t *);
369: eval = va_arg(ap, int);
370: fmt = va_arg(ap, const char *);
371: #endif
372: verr(eval, fmt, ap);
373: auth_close(as);
374: va_end(ap);
1.28 deraadt 375: }
376:
1.36 millert 377: void
378: #ifdef __STDC__
379: auth_errx(auth_session_t *as, int eval, const char *fmt, ...)
380: #else
381: auth_errx(va_alist)
382: va_dcl
383: #endif
1.28 deraadt 384: {
1.36 millert 385: va_list ap;
386: #ifdef __STDC__
387: va_start(ap, fmt);
388: #else
389: auth_session_t *as;
390: int eval;
391: const char *fmt;
392:
393: va_start(ap);
394: as = va_arg(ap, auth_session_t *);
395: eval = va_arg(ap, int);
396: fmt = va_arg(ap, const char *);
397: #endif
398: verrx(eval, fmt, ap);
399: auth_close(as);
400: va_end(ap);
1.1 deraadt 401: }
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