Annotation of src/usr.bin/su/su.c, Revision 1.57
1.57 ! deraadt 1: /* $OpenBSD: su.c,v 1.56 2003/11/09 20:13:58 otto 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.
1.52 millert 15: * 3. Neither the name of the University nor the names of its contributors
1.1 deraadt 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: #ifndef lint
1.41 millert 33: static const char copyright[] =
1.1 deraadt 34: "@(#) Copyright (c) 1988 The Regents of the University of California.\n\
35: All rights reserved.\n";
36: #endif /* not lint */
37:
38: #ifndef lint
1.41 millert 39: #if 0
40: static const char sccsid[] = "from: @(#)su.c 5.26 (Berkeley) 7/6/91";
41: #else
1.57 ! deraadt 42: static const char rcsid[] = "$OpenBSD: su.c,v 1.56 2003/11/09 20:13:58 otto Exp $";
1.41 millert 43: #endif
1.1 deraadt 44: #endif /* not lint */
45:
46: #include <sys/param.h>
47: #include <sys/time.h>
48: #include <sys/resource.h>
1.8 millert 49:
50: #include <err.h>
51: #include <errno.h>
52: #include <grp.h>
1.33 millert 53: #include <login_cap.h>
1.8 millert 54: #include <paths.h>
55: #include <pwd.h>
1.1 deraadt 56: #include <stdio.h>
57: #include <stdlib.h>
58: #include <string.h>
1.8 millert 59: #include <syslog.h>
1.1 deraadt 60: #include <unistd.h>
1.47 millert 61: #include <utmp.h>
1.36 millert 62: #include <stdarg.h>
63: #include <bsd_auth.h>
64:
1.47 millert 65: char *getloginname(void);
1.43 millert 66: char *ontty(void);
1.53 millert 67: int chshell(const char *);
1.47 millert 68: int verify_user(char *, struct passwd *, char *, login_cap_t *,
69: auth_session_t *);
1.43 millert 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
1.47 millert 75: main(int argc, char **argv)
1.1 deraadt 76: {
1.54 deraadt 77: int asme = 0, asthem = 0, ch, fastlogin = 0, emlogin = 0, prio;
1.45 deraadt 78: char *user, *shell = NULL, *avshell, *username, **np;
1.47 millert 79: char *class = NULL, *style = NULL, *p;
1.45 deraadt 80: enum { UNSET, YES, NO } iscsh = UNSET;
81: char avshellbuf[MAXPATHLEN];
1.1 deraadt 82: extern char **environ;
1.45 deraadt 83: auth_session_t *as;
1.36 millert 84: struct passwd *pwd;
1.45 deraadt 85: login_cap_t *lc;
1.9 millert 86: uid_t ruid;
1.54 deraadt 87: u_int flags;
1.1 deraadt 88:
1.50 millert 89: while ((ch = getopt(argc, argv, "a:c:fKLlm-")) != -1)
1.45 deraadt 90: switch (ch) {
1.36 millert 91: case 'a':
92: if (style)
93: usage();
94: style = optarg;
1.1 deraadt 95: break;
1.33 millert 96: case 'c':
1.36 millert 97: if (class)
98: usage();
1.33 millert 99: class = optarg;
100: break;
1.1 deraadt 101: case 'f':
102: fastlogin = 1;
103: break;
1.36 millert 104: case 'K':
105: if (style)
106: usage();
107: style = "passwd";
108: break;
1.47 millert 109: case 'L':
110: emlogin = 1;
111: break;
112: case 'l':
1.1 deraadt 113: case '-':
114: asme = 0;
115: asthem = 1;
116: break;
117: case 'm':
118: asme = 1;
119: asthem = 0;
120: break;
121: default:
1.36 millert 122: usage();
1.1 deraadt 123: }
124: argv += optind;
125:
126: errno = 0;
127: prio = getpriority(PRIO_PROCESS, 0);
128: if (errno)
129: prio = 0;
130: (void)setpriority(PRIO_PROCESS, 0, -2);
131: openlog("su", LOG_CONS, 0);
132:
1.36 millert 133: if ((as = auth_open()) == NULL) {
134: syslog(LOG_ERR, "auth_open: %m");
1.39 millert 135: err(1, "unable to initialize BSD authentication");
1.36 millert 136: }
1.39 millert 137: auth_setoption(as, "login", "yes");
1.36 millert 138:
1.1 deraadt 139: /* get current login name and shell */
140: ruid = getuid();
141: username = getlogin();
1.40 hin 142:
1.47 millert 143: if (ruid && class)
144: auth_errx(as, 1, "only the superuser may specify a login class");
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:
1.47 millert 166: for (;;) {
167: /* get target user, default to root unless in -L mode */
168: if (*argv) {
169: user = *argv;
170: } else if (emlogin) {
171: if ((user = getloginname()) == NULL) {
172: auth_close(as);
173: exit(1);
174: }
175: } else {
176: user = "root";
177: }
178: /* style may be specified as part of the username */
179: if ((p = strchr(user, ':')) != NULL) {
180: *p++ = '\0';
1.49 millert 181: style = p; /* XXX overrides -a flag */
182: }
1.47 millert 183:
1.36 millert 184: /*
1.47 millert 185: * Clean and setup our current authentication session.
186: * Note that options *are* not cleared.
1.36 millert 187: */
1.47 millert 188: auth_clean(as);
189: if (auth_setitem(as, AUTHV_INTERACTIVE, "True") != 0 ||
190: auth_setitem(as, AUTHV_NAME, user) != 0)
191: auth_errx(as, 1, "can't allocate memory");
192: if ((user = auth_getitem(as, AUTHV_NAME)) == NULL)
193: auth_errx(as, 1, "internal error");
194: if (auth_setpwd(as, NULL) || (pwd = auth_getpwd(as)) == NULL) {
195: if (emlogin)
196: pwd = NULL;
197: else
198: auth_errx(as, 1, "unknown login %s", user);
1.1 deraadt 199: }
1.36 millert 200:
1.47 millert 201: /* If the user specified a login class, use it */
202: if (!class && pwd && pwd->pw_class && pwd->pw_class[0] != '\0')
203: class = pwd->pw_class;
204: if ((lc = login_getclass(class)) == NULL)
205: auth_errx(as, 1, "no such login class: %s",
206: class ? class : LOGIN_DEFCLASS);
207:
208: if ((ruid == 0 && !emlogin) ||
209: verify_user(username, pwd, style, lc, as) == 0)
210: break;
211: syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s%s",
212: username, user, ontty());
213: if (!emlogin) {
1.36 millert 214: fprintf(stderr, "Sorry\n");
215: auth_close(as);
216: exit(1);
1.1 deraadt 217: }
1.47 millert 218: fprintf(stderr, "Login incorrect\n");
1.1 deraadt 219: }
220:
221: if (asme) {
222: /* if asme and non-standard target shell, must be root */
1.8 millert 223: if (!chshell(pwd->pw_shell) && ruid)
1.36 millert 224: auth_errx(as, 1, "permission denied (shell).");
1.1 deraadt 225: } else if (pwd->pw_shell && *pwd->pw_shell) {
1.47 millert 226: if ((shell = strdup(pwd->pw_shell)) == NULL)
227: auth_errx(as, 1, "can't allocate memory");
1.1 deraadt 228: iscsh = UNSET;
229: } else {
230: shell = _PATH_BSHELL;
231: iscsh = NO;
232: }
233:
1.30 deraadt 234: if ((p = strrchr(shell, '/')))
1.1 deraadt 235: avshell = p+1;
236: else
237: avshell = shell;
238:
239: /* if we're forking a csh, we want to slightly muck the args */
240: if (iscsh == UNSET)
241: iscsh = strcmp(avshell, "csh") ? NO : YES;
242:
243: if (!asme) {
244: if (asthem) {
245: p = getenv("TERM");
1.23 deraadt 246: if ((environ = calloc(1, sizeof (char *))) == NULL)
1.36 millert 247: auth_errx(as, 1, "calloc");
1.33 millert 248: if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETPATH))
1.36 millert 249: auth_err(as, 1, "unable to set user context");
250: if (p && setenv("TERM", p, 1) == -1)
251: auth_err(as, 1, "unable to set environment");
1.5 deraadt 252:
1.57 ! deraadt 253: setegid(pwd->pw_gid);
1.5 deraadt 254: seteuid(pwd->pw_uid);
1.8 millert 255: if (chdir(pwd->pw_dir) < 0)
1.36 millert 256: auth_err(as, 1, "%s", pwd->pw_dir);
1.57 ! deraadt 257: setegid(0); /* XXX use a saved gid instead? */
1.5 deraadt 258: seteuid(0);
1.33 millert 259: } else if (pwd->pw_uid == 0) {
260: if (setusercontext(lc,
261: pwd, pwd->pw_uid, LOGIN_SETPATH|LOGIN_SETUMASK))
1.36 millert 262: auth_err(as, 1, "unable to set user context");
1.1 deraadt 263: }
1.15 millert 264: if (asthem || pwd->pw_uid) {
1.34 deraadt 265: if (setenv("LOGNAME", pwd->pw_name, 1) == -1 ||
266: setenv("USER", pwd->pw_name, 1) == -1)
1.36 millert 267: auth_err(as, 1, "unable to set environment");
1.15 millert 268: }
1.34 deraadt 269: if (setenv("HOME", pwd->pw_dir, 1) == -1 ||
270: setenv("SHELL", shell, 1) == -1)
1.36 millert 271: auth_err(as, 1, "unable to set environment");
1.34 deraadt 272: }
1.28 deraadt 273:
1.47 millert 274: np = *argv ? argv : argv - 1;
1.1 deraadt 275: if (iscsh == YES) {
276: if (fastlogin)
277: *np-- = "-f";
278: if (asme)
279: *np-- = "-m";
280: }
281:
282: if (asthem) {
283: avshellbuf[0] = '-';
1.36 millert 284: strlcpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 1);
1.1 deraadt 285: avshell = avshellbuf;
286: } else if (iscsh == YES) {
287: /* csh strips the first character... */
288: avshellbuf[0] = '_';
1.36 millert 289: strlcpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 1);
1.1 deraadt 290: avshell = avshellbuf;
291: }
1.45 deraadt 292:
1.1 deraadt 293: *np = avshell;
294:
295: if (ruid != 0)
296: syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s",
297: username, user, ontty());
298:
299: (void)setpriority(PRIO_PROCESS, 0, prio);
1.51 millert 300: if (emlogin) {
1.48 millert 301: flags = LOGIN_SETALL & ~LOGIN_SETPATH;
1.51 millert 302: /*
1.55 miod 303: * Only call setlogin() if this process is a session leader.
1.51 millert 304: * In practice, this means the login name will be set only if
305: * we are exec'd by a shell. This is important because
306: * otherwise the parent shell's login name would change too.
307: */
308: if (getsid(0) != getpid())
309: flags &= ~LOGIN_SETLOGIN;
310: } else
1.48 millert 311: flags = (asthem ? (LOGIN_SETPRIORITY | LOGIN_SETUMASK) : 0) |
312: LOGIN_SETRESOURCES | LOGIN_SETGROUP | LOGIN_SETUSER;
313: if (setusercontext(lc, pwd, pwd->pw_uid, flags) != 0)
1.36 millert 314: auth_err(as, 1, "unable to set user context");
315: if (pwd->pw_uid && auth_approval(as, lc, pwd->pw_name, "su") <= 0)
316: auth_err(as, 1, "approval failure");
317: auth_close(as);
1.1 deraadt 318:
319: execv(shell, np);
1.32 millert 320: err(1, "%s", shell);
1.1 deraadt 321: }
322:
323: int
1.47 millert 324: verify_user(char *from, struct passwd *pwd, char *style,
325: login_cap_t *lc, auth_session_t *as)
326: {
327: struct group *gr;
328: char **g, *cp;
329: int authok;
330:
331: /*
332: * If we are trying to become root and the default style
333: * is being used, don't bother to look it up (we might be
334: * be su'ing up to fix /etc/login.conf)
335: */
336: if ((pwd == NULL || pwd->pw_uid != 0 || style == NULL ||
337: strcmp(style, LOGIN_DEFSTYLE) != 0) &&
338: (style = login_getstyle(lc, style, "auth-su")) == NULL)
339: auth_errx(as, 1, "invalid authentication type");
340:
341: /*
342: * Let the authentication program know whether they are
343: * in group wheel or not (if trying to become super user)
344: */
345: if (pwd != NULL && pwd->pw_uid == 0 && (gr = getgrgid(0)) != NULL &&
346: gr->gr_mem != NULL && *(gr->gr_mem) != NULL) {
347: for (g = gr->gr_mem; *g; ++g) {
348: if (strcmp(from, *g) == 0) {
349: auth_setoption(as, "wheel", "yes");
350: break;
351: }
352: }
353: if (!*g)
354: auth_setoption(as, "wheel", "no");
355: }
356:
357: auth_verify(as, style, NULL, lc->lc_class, (char *)NULL);
358: authok = auth_getstate(as);
359: if ((authok & AUTH_ALLOW) == 0) {
360: if ((cp = auth_getvalue(as, "errormsg")) != NULL)
361: fprintf(stderr, "%s\n", cp);
362: return(1);
363: }
364: return(0);
365: }
366:
367: int
1.53 millert 368: chshell(const char *sh)
1.1 deraadt 369: {
1.36 millert 370: char *cp;
1.53 millert 371: int found = 0;
1.1 deraadt 372:
1.53 millert 373: setusershell();
374: while ((cp = getusershell()) != NULL) {
375: if (strcmp(cp, sh) == 0) {
376: found = 1;
377: break;
378: }
379: }
380: endusershell();
381: return (found);
1.1 deraadt 382: }
383:
384: char *
1.47 millert 385: ontty(void)
1.1 deraadt 386: {
387: static char buf[MAXPATHLEN + 4];
1.36 millert 388: char *p;
1.1 deraadt 389:
390: buf[0] = 0;
1.30 deraadt 391: if ((p = ttyname(STDERR_FILENO)))
1.8 millert 392: snprintf(buf, sizeof(buf), " on %s", p);
1.1 deraadt 393: return (buf);
394: }
395:
1.47 millert 396: /*
397: * Allow for a '.' and 16 characters for any instance as well as
1.56 otto 398: * space for a ':' and 16 characters defining the authentication type.
1.47 millert 399: */
400: #define NBUFSIZ (UT_NAMESIZE + 1 + 16 + 1 + 16)
401:
402: char *
403: getloginname(void)
404: {
405: static char nbuf[NBUFSIZ], *p;
406: int ch;
407:
408: for (;;) {
409: (void)printf("login: ");
410: for (p = nbuf; (ch = getchar()) != '\n'; ) {
411: if (ch == EOF)
412: return (NULL);
413: if (p < nbuf + (NBUFSIZ - 1))
414: *p++ = ch;
415: }
416: if (p > nbuf) {
417: if (nbuf[0] == '-') {
418: (void)fprintf(stderr,
419: "login names may not start with '-'.\n");
420: } else {
421: *p = '\0';
422: break;
423: }
424: }
425: }
426: return (nbuf);
427: }
428:
1.36 millert 429: void
1.47 millert 430: usage(void)
1.1 deraadt 431: {
1.36 millert 432: extern char *__progname;
1.1 deraadt 433:
1.47 millert 434: fprintf(stderr, "usage: %s [-fKLlm] [-a auth-type] [-c login-class] "
435: "[login [shell arguments]]\n", __progname);
1.36 millert 436: exit(1);
1.1 deraadt 437: }
438:
1.36 millert 439: void
440: auth_err(auth_session_t *as, int eval, const char *fmt, ...)
1.1 deraadt 441: {
1.36 millert 442: va_list ap;
1.46 millert 443:
1.36 millert 444: va_start(ap, fmt);
1.46 millert 445: vwarn(fmt, ap);
446: va_end(ap);
1.36 millert 447: auth_close(as);
1.46 millert 448: exit(eval);
1.28 deraadt 449: }
450:
1.36 millert 451: void
452: auth_errx(auth_session_t *as, int eval, const char *fmt, ...)
1.28 deraadt 453: {
1.36 millert 454: va_list ap;
1.46 millert 455:
1.36 millert 456: va_start(ap, fmt);
1.46 millert 457: vwarnx(fmt, ap);
458: va_end(ap);
1.36 millert 459: auth_close(as);
1.46 millert 460: exit(eval);
1.1 deraadt 461: }
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