Annotation of src/usr.bin/su/su.c, Revision 1.9
1.9 ! millert 1: /* $OpenBSD: su.c,v 1.8 1996/10/12 20:40:37 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
37: char copyright[] =
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
43: /*static char sccsid[] = "from: @(#)su.c 5.26 (Berkeley) 7/6/91";*/
1.9 ! millert 44: static char rcsid[] = "$OpenBSD: su.c,v 1.8 1996/10/12 20:40:37 millert Exp $";
1.1 deraadt 45: #endif /* not lint */
46:
47: #include <sys/param.h>
48: #include <sys/time.h>
49: #include <sys/resource.h>
1.8 millert 50:
51: #include <err.h>
52: #include <errno.h>
53: #include <grp.h>
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>
1.8 millert 61:
62: #ifdef SKEY
63: #include <skey.h>
64: #endif
1.1 deraadt 65:
66: #ifdef KERBEROS
67: #include <kerberosIV/des.h>
68: #include <kerberosIV/krb.h>
69: #include <netdb.h>
70:
71: #define ARGSTR "-Kflm"
72:
73: int use_kerberos = 1;
74: #else
75: #define ARGSTR "-flm"
76: #endif
77:
1.8 millert 78: char *ontty __P((void));
79: int chshell __P((char *));
1.1 deraadt 80:
81: int
82: main(argc, argv)
83: int argc;
84: char **argv;
85: {
86: extern char **environ;
87: register struct passwd *pwd;
88: register char *p, **g;
89: struct group *gr;
1.9 ! millert 90: uid_t ruid;
1.1 deraadt 91: int asme, ch, asthem, fastlogin, prio;
92: enum { UNSET, YES, NO } iscsh = UNSET;
93: char *user, *shell, *avshell, *username, *cleanenv[10], **np;
94: char shellbuf[MAXPATHLEN], avshellbuf[MAXPATHLEN];
95:
96: asme = asthem = fastlogin = 0;
97: while ((ch = getopt(argc, argv, ARGSTR)) != EOF)
98: switch((char)ch) {
99: #ifdef KERBEROS
100: case 'K':
101: use_kerberos = 0;
102: break;
103: #endif
104: case 'f':
105: fastlogin = 1;
106: break;
107: case '-':
108: case 'l':
109: asme = 0;
110: asthem = 1;
111: break;
112: case 'm':
113: asme = 1;
114: asthem = 0;
115: break;
116: case '?':
117: default:
1.7 millert 118: (void)fprintf(stderr,
119: "usage: su [%s] [login [shell arguments]]\n",
1.1 deraadt 120: ARGSTR);
121: exit(1);
122: }
123: argv += optind;
124:
125: errno = 0;
126: prio = getpriority(PRIO_PROCESS, 0);
127: if (errno)
128: prio = 0;
129: (void)setpriority(PRIO_PROCESS, 0, -2);
130: openlog("su", LOG_CONS, 0);
131:
132: /* get current login name and shell */
133: ruid = getuid();
134: username = getlogin();
135: if (username == NULL || (pwd = getpwnam(username)) == NULL ||
136: pwd->pw_uid != ruid)
137: pwd = getpwuid(ruid);
1.8 millert 138: if (pwd == NULL)
139: errx(1, "who are you?");
1.9 ! millert 140: if ((username = strdup(pwd->pw_name)) == NULL)
! 141: err(1, "can't allocate memory");
1.1 deraadt 142: if (asme)
143: if (pwd->pw_shell && *pwd->pw_shell)
1.9 ! millert 144: shell = strcpy(shellbuf, pwd->pw_shell);
1.1 deraadt 145: else {
146: shell = _PATH_BSHELL;
147: iscsh = NO;
148: }
149:
150: /* get target login information, default to root */
151: user = *argv ? *argv : "root";
152: np = *argv ? argv : argv-1;
153:
1.8 millert 154: if ((pwd = getpwnam(user)) == NULL)
155: errx(1, "unknown login %s", user);
1.1 deraadt 156:
157: if (ruid) {
158: #ifdef KERBEROS
159: if (!use_kerberos || kerberos(username, user, pwd->pw_uid))
160: #endif
161: {
162: /* only allow those in group zero to su to root. */
1.3 deraadt 163: if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0))
164: && gr->gr_mem && *(gr->gr_mem))
1.1 deraadt 165: for (g = gr->gr_mem;; ++g) {
1.8 millert 166: if (!*g)
167: errx(1, "you are not in the correct group to su %s.", user);
168: if (strcmp(username, *g) == 0)
1.1 deraadt 169: break;
170: }
171: /* if target requires a password, verify it */
172: if (*pwd->pw_passwd) {
173: p = getpass("Password:");
174: #ifdef SKEY
175: if (strcasecmp(p, "s/key") == 0) {
1.8 millert 176: if (skey_haskey(user))
177: errx(1, "Sorry, you have no s/key.");
178: else if (skey_authenticate(user))
179: goto badlogin;
1.1 deraadt 180: } else
181: #endif
182: if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) {
183: badlogin:
184: fprintf(stderr, "Sorry\n");
185: syslog(LOG_AUTH|LOG_WARNING,
186: "BAD SU %s to %s%s", username,
187: user, ontty());
188: exit(1);
189: }
190: }
191: }
1.8 millert 192: if (pwd->pw_expire && time(NULL) >= pwd->pw_expire) {
193: fprintf(stderr, "Sorry - account expired\n");
194: syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s%s", username,
195: user, ontty());
196: exit(1);
197: }
1.1 deraadt 198: }
199:
200: if (asme) {
201: /* if asme and non-standard target shell, must be root */
1.8 millert 202: if (!chshell(pwd->pw_shell) && ruid)
203: errx(1, "permission denied (shell).");
1.1 deraadt 204: } else if (pwd->pw_shell && *pwd->pw_shell) {
205: shell = pwd->pw_shell;
206: iscsh = UNSET;
207: } else {
208: shell = _PATH_BSHELL;
209: iscsh = NO;
210: }
211:
1.8 millert 212: if (p = strrchr(shell, '/'))
1.1 deraadt 213: avshell = p+1;
214: else
215: avshell = shell;
216:
217: /* if we're forking a csh, we want to slightly muck the args */
218: if (iscsh == UNSET)
219: iscsh = strcmp(avshell, "csh") ? NO : YES;
220:
221: /* set permissions */
1.8 millert 222: if (setgid(pwd->pw_gid) < 0)
223: err(1, "setgid");
224: if (initgroups(user, pwd->pw_gid))
225: err(1, "initgroups failed");
226: if (setuid(pwd->pw_uid) < 0)
227: err(1, "setuid");
1.1 deraadt 228:
229: if (!asme) {
230: if (asthem) {
231: p = getenv("TERM");
232: cleanenv[0] = NULL;
233: environ = cleanenv;
234: (void)setenv("PATH", _PATH_DEFPATH, 1);
1.6 deraadt 235: if (p)
236: (void)setenv("TERM", p, 1);
1.5 deraadt 237:
238: seteuid(pwd->pw_uid);
239: setegid(pwd->pw_gid);
1.8 millert 240: if (chdir(pwd->pw_dir) < 0)
241: errx(1, "no directory");
1.5 deraadt 242: seteuid(0);
243: setegid(0); /* XXX use a saved gid instead? */
1.1 deraadt 244: }
245: if (asthem || pwd->pw_uid)
246: (void)setenv("USER", pwd->pw_name, 1);
247: (void)setenv("HOME", pwd->pw_dir, 1);
248: (void)setenv("SHELL", shell, 1);
249: }
250:
251: if (iscsh == YES) {
252: if (fastlogin)
253: *np-- = "-f";
254: if (asme)
255: *np-- = "-m";
256: }
257:
258: if (asthem) {
259: avshellbuf[0] = '-';
260: strcpy(avshellbuf+1, avshell);
261: avshell = avshellbuf;
262: } else if (iscsh == YES) {
263: /* csh strips the first character... */
264: avshellbuf[0] = '_';
265: strcpy(avshellbuf+1, avshell);
266: avshell = avshellbuf;
267: }
268:
269: *np = avshell;
270:
271: if (ruid != 0)
272: syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s",
273: username, user, ontty());
274:
275: (void)setpriority(PRIO_PROCESS, 0, prio);
276:
277: execv(shell, np);
1.9 ! millert 278: err(1, shell);
1.1 deraadt 279: }
280:
281: int
282: chshell(sh)
283: char *sh;
284: {
285: register char *cp;
286:
287: while ((cp = getusershell()) != NULL)
1.8 millert 288: if (strcmp(cp, sh) == 0)
1.1 deraadt 289: return (1);
290: return (0);
291: }
292:
293: char *
294: ontty()
295: {
296: char *p, *ttyname();
297: static char buf[MAXPATHLEN + 4];
298:
299: buf[0] = 0;
300: if (p = ttyname(STDERR_FILENO))
1.8 millert 301: snprintf(buf, sizeof(buf), " on %s", p);
1.1 deraadt 302: return (buf);
303: }
304:
305: #ifdef KERBEROS
306: kerberos(username, user, uid)
307: char *username, *user;
308: int uid;
309: {
310: KTEXT_ST ticket;
311: AUTH_DAT authdata;
312: struct hostent *hp;
313: register char *p;
314: int kerno;
315: u_long faddr;
316: char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN];
317: char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN];
318: char *ontty(), *krb_get_phost();
319:
320: if (krb_get_lrealm(lrealm, 1) != KSUCCESS)
321: return (1);
322: if (koktologin(username, lrealm, user) && !uid) {
323: (void)fprintf(stderr, "kerberos su: not in %s's ACL.\n", user);
324: return (1);
325: }
1.8 millert 326: (void)snprintf(krbtkfile, sizeof(krbtkfile), "%s_%s_%d", TKT_ROOT,
327: user, getuid());
1.1 deraadt 328:
329: (void)setenv("KRBTKFILE", krbtkfile, 1);
330: (void)krb_set_tkt_string(krbtkfile);
331: /*
332: * Set real as well as effective ID to 0 for the moment,
333: * to make the kerberos library do the right thing.
334: */
335: if (setuid(0) < 0) {
1.8 millert 336: warn("setuid");
1.1 deraadt 337: return (1);
338: }
339:
340: /*
341: * Little trick here -- if we are su'ing to root,
342: * we need to get a ticket for "xxx.root", where xxx represents
343: * the name of the person su'ing. Otherwise (non-root case),
344: * we need to get a ticket for "yyy.", where yyy represents
345: * the name of the person being su'd to, and the instance is null
346: *
347: * We should have a way to set the ticket lifetime,
348: * with a system default for root.
349: */
350: kerno = krb_get_pw_in_tkt((uid == 0 ? username : user),
351: (uid == 0 ? "root" : ""), lrealm,
352: "krbtgt", lrealm, DEFAULT_TKT_LIFE, 0);
353:
354: if (kerno != KSUCCESS) {
355: if (kerno == KDC_PR_UNKNOWN) {
1.8 millert 356: warnx("kerberos principal unknown: %s.%s@%s",
1.1 deraadt 357: (uid == 0 ? username : user),
358: (uid == 0 ? "root" : ""), lrealm);
359: return (1);
360: }
1.8 millert 361: warnx("unable to su: %s", krb_err_txt[kerno]);
1.1 deraadt 362: syslog(LOG_NOTICE|LOG_AUTH,
363: "BAD Kerberos SU: %s to %s%s: %s",
364: username, user, ontty(), krb_err_txt[kerno]);
365: return (1);
366: }
367:
368: if (chown(krbtkfile, uid, -1) < 0) {
1.8 millert 369: warn("chown");
1.1 deraadt 370: (void)unlink(krbtkfile);
371: return (1);
372: }
373:
374: (void)setpriority(PRIO_PROCESS, 0, -2);
375:
376: if (gethostname(hostname, sizeof(hostname)) == -1) {
1.8 millert 377: warn("gethostname");
1.1 deraadt 378: dest_tkt();
379: return (1);
380: }
381:
382: (void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost));
383: savehost[sizeof(savehost) - 1] = '\0';
384:
385: kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33);
386:
387: if (kerno == KDC_PR_UNKNOWN) {
1.8 millert 388: warnx("Warning: TGT not verified.");
1.1 deraadt 389: syslog(LOG_NOTICE|LOG_AUTH,
390: "%s to %s%s, TGT not verified (%s); %s.%s not registered?",
391: username, user, ontty(), krb_err_txt[kerno],
392: "rcmd", savehost);
393: } else if (kerno != KSUCCESS) {
1.8 millert 394: warnx("Unable to use TGT: %s", krb_err_txt[kerno]);
1.1 deraadt 395: syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s",
396: username, user, ontty(), krb_err_txt[kerno]);
397: dest_tkt();
398: return (1);
399: } else {
400: if (!(hp = gethostbyname(hostname))) {
1.8 millert 401: warnx("can't get addr of %s", hostname);
1.1 deraadt 402: dest_tkt();
403: return (1);
404: }
405: (void)bcopy((char *)hp->h_addr, (char *)&faddr, sizeof(faddr));
406:
407: if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr,
408: &authdata, "")) != KSUCCESS) {
1.8 millert 409: warnx("unable to verify rcmd ticket: %s",
410: krb_err_txt[kerno]);
1.1 deraadt 411: syslog(LOG_NOTICE|LOG_AUTH,
412: "failed su: %s to %s%s: %s", username,
413: user, ontty(), krb_err_txt[kerno]);
414: dest_tkt();
415: return (1);
416: }
417: }
418: return (0);
419: }
420:
421: koktologin(name, realm, toname)
422: char *name, *realm, *toname;
423: {
424: register AUTH_DAT *kdata;
425: AUTH_DAT kdata_st;
426:
427: kdata = &kdata_st;
428: bzero((caddr_t) kdata, sizeof(*kdata));
429: (void)strcpy(kdata->pname, name);
430: (void)strcpy(kdata->pinst,
431: ((strcmp(toname, "root") == 0) ? "root" : ""));
432: (void)strcpy(kdata->prealm, realm);
433: return (kuserok(kdata, toname));
434: }
435: #endif
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