Annotation of src/usr.bin/su/su.c, Revision 1.8
1.8 ! millert 1: /* $OpenBSD: su.c,v 1.7 1996/10/12 17:13:57 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";*/
1.8 ! millert 44: static char rcsid[] = "$OpenBSD: su.c,v 1.7 1996/10/12 17:13:57 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;
90: uid_t ruid, getuid();
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?");
1.1 deraadt 140: username = strdup(pwd->pw_name);
141: if (asme)
142: if (pwd->pw_shell && *pwd->pw_shell)
143: shell = strcpy(shellbuf, pwd->pw_shell);
144: else {
145: shell = _PATH_BSHELL;
146: iscsh = NO;
147: }
148:
149: /* get target login information, default to root */
150: user = *argv ? *argv : "root";
151: np = *argv ? argv : argv-1;
152:
1.8 ! millert 153: if ((pwd = getpwnam(user)) == NULL)
! 154: errx(1, "unknown login %s", user);
1.1 deraadt 155:
156: if (ruid) {
157: #ifdef KERBEROS
158: if (!use_kerberos || kerberos(username, user, pwd->pw_uid))
159: #endif
160: {
161: /* only allow those in group zero to su to root. */
1.3 deraadt 162: if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0))
163: && gr->gr_mem && *(gr->gr_mem))
1.1 deraadt 164: for (g = gr->gr_mem;; ++g) {
1.8 ! millert 165: if (!*g)
! 166: errx(1, "you are not in the correct group to su %s.", user);
! 167: if (strcmp(username, *g) == 0)
1.1 deraadt 168: break;
169: }
170: /* if target requires a password, verify it */
171: if (*pwd->pw_passwd) {
172: p = getpass("Password:");
173: #ifdef SKEY
174: if (strcasecmp(p, "s/key") == 0) {
1.8 ! millert 175: if (skey_haskey(user))
! 176: errx(1, "Sorry, you have no s/key.");
! 177: else if (skey_authenticate(user))
! 178: goto badlogin;
1.1 deraadt 179: } else
180: #endif
181: if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) {
182: badlogin:
183: fprintf(stderr, "Sorry\n");
184: syslog(LOG_AUTH|LOG_WARNING,
185: "BAD SU %s to %s%s", username,
186: user, ontty());
187: exit(1);
188: }
189: }
190: }
1.8 ! millert 191: if (pwd->pw_expire && time(NULL) >= pwd->pw_expire) {
! 192: fprintf(stderr, "Sorry - account expired\n");
! 193: syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s%s", username,
! 194: user, ontty());
! 195: exit(1);
! 196: }
1.1 deraadt 197: }
198:
199: if (asme) {
200: /* if asme and non-standard target shell, must be root */
1.8 ! millert 201: if (!chshell(pwd->pw_shell) && ruid)
! 202: errx(1, "permission denied (shell).");
1.1 deraadt 203: } else if (pwd->pw_shell && *pwd->pw_shell) {
204: shell = pwd->pw_shell;
205: iscsh = UNSET;
206: } else {
207: shell = _PATH_BSHELL;
208: iscsh = NO;
209: }
210:
1.8 ! millert 211: if (p = strrchr(shell, '/'))
1.1 deraadt 212: avshell = p+1;
213: else
214: avshell = shell;
215:
216: /* if we're forking a csh, we want to slightly muck the args */
217: if (iscsh == UNSET)
218: iscsh = strcmp(avshell, "csh") ? NO : YES;
219:
220: /* set permissions */
1.8 ! millert 221: if (setgid(pwd->pw_gid) < 0)
! 222: err(1, "setgid");
! 223: if (initgroups(user, pwd->pw_gid))
! 224: err(1, "initgroups failed");
! 225: if (setuid(pwd->pw_uid) < 0)
! 226: err(1, "setuid");
1.1 deraadt 227:
228: if (!asme) {
229: if (asthem) {
230: p = getenv("TERM");
231: cleanenv[0] = NULL;
232: environ = cleanenv;
233: (void)setenv("PATH", _PATH_DEFPATH, 1);
1.6 deraadt 234: if (p)
235: (void)setenv("TERM", p, 1);
1.5 deraadt 236:
237: seteuid(pwd->pw_uid);
238: setegid(pwd->pw_gid);
1.8 ! millert 239: if (chdir(pwd->pw_dir) < 0)
! 240: errx(1, "no directory");
1.5 deraadt 241: seteuid(0);
242: setegid(0); /* XXX use a saved gid instead? */
1.1 deraadt 243: }
244: if (asthem || pwd->pw_uid)
245: (void)setenv("USER", pwd->pw_name, 1);
246: (void)setenv("HOME", pwd->pw_dir, 1);
247: (void)setenv("SHELL", shell, 1);
248: }
249:
250: if (iscsh == YES) {
251: if (fastlogin)
252: *np-- = "-f";
253: if (asme)
254: *np-- = "-m";
255: }
256:
257: if (asthem) {
258: avshellbuf[0] = '-';
259: strcpy(avshellbuf+1, avshell);
260: avshell = avshellbuf;
261: } else if (iscsh == YES) {
262: /* csh strips the first character... */
263: avshellbuf[0] = '_';
264: strcpy(avshellbuf+1, avshell);
265: avshell = avshellbuf;
266: }
267:
268: *np = avshell;
269:
270: if (ruid != 0)
271: syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s",
272: username, user, ontty());
273:
274: (void)setpriority(PRIO_PROCESS, 0, prio);
275:
276: execv(shell, np);
1.8 ! millert 277: err(1, "%s", shell);
1.1 deraadt 278: }
279:
280: int
281: chshell(sh)
282: char *sh;
283: {
284: register char *cp;
285:
286: while ((cp = getusershell()) != NULL)
1.8 ! millert 287: if (strcmp(cp, sh) == 0)
1.1 deraadt 288: return (1);
289: return (0);
290: }
291:
292: char *
293: ontty()
294: {
295: char *p, *ttyname();
296: static char buf[MAXPATHLEN + 4];
297:
298: buf[0] = 0;
299: if (p = ttyname(STDERR_FILENO))
1.8 ! millert 300: snprintf(buf, sizeof(buf), " on %s", p);
1.1 deraadt 301: return (buf);
302: }
303:
304: #ifdef KERBEROS
305: kerberos(username, user, uid)
306: char *username, *user;
307: int uid;
308: {
309: KTEXT_ST ticket;
310: AUTH_DAT authdata;
311: struct hostent *hp;
312: register char *p;
313: int kerno;
314: u_long faddr;
315: char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN];
316: char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN];
317: char *ontty(), *krb_get_phost();
318:
319: if (krb_get_lrealm(lrealm, 1) != KSUCCESS)
320: return (1);
321: if (koktologin(username, lrealm, user) && !uid) {
322: (void)fprintf(stderr, "kerberos su: not in %s's ACL.\n", user);
323: return (1);
324: }
1.8 ! millert 325: (void)snprintf(krbtkfile, sizeof(krbtkfile), "%s_%s_%d", TKT_ROOT,
! 326: user, getuid());
1.1 deraadt 327:
328: (void)setenv("KRBTKFILE", krbtkfile, 1);
329: (void)krb_set_tkt_string(krbtkfile);
330: /*
331: * Set real as well as effective ID to 0 for the moment,
332: * to make the kerberos library do the right thing.
333: */
334: if (setuid(0) < 0) {
1.8 ! millert 335: warn("setuid");
1.1 deraadt 336: return (1);
337: }
338:
339: /*
340: * Little trick here -- if we are su'ing to root,
341: * we need to get a ticket for "xxx.root", where xxx represents
342: * the name of the person su'ing. Otherwise (non-root case),
343: * we need to get a ticket for "yyy.", where yyy represents
344: * the name of the person being su'd to, and the instance is null
345: *
346: * We should have a way to set the ticket lifetime,
347: * with a system default for root.
348: */
349: kerno = krb_get_pw_in_tkt((uid == 0 ? username : user),
350: (uid == 0 ? "root" : ""), lrealm,
351: "krbtgt", lrealm, DEFAULT_TKT_LIFE, 0);
352:
353: if (kerno != KSUCCESS) {
354: if (kerno == KDC_PR_UNKNOWN) {
1.8 ! millert 355: warnx("kerberos principal unknown: %s.%s@%s",
1.1 deraadt 356: (uid == 0 ? username : user),
357: (uid == 0 ? "root" : ""), lrealm);
358: return (1);
359: }
1.8 ! millert 360: warnx("unable to su: %s", krb_err_txt[kerno]);
1.1 deraadt 361: syslog(LOG_NOTICE|LOG_AUTH,
362: "BAD Kerberos SU: %s to %s%s: %s",
363: username, user, ontty(), krb_err_txt[kerno]);
364: return (1);
365: }
366:
367: if (chown(krbtkfile, uid, -1) < 0) {
1.8 ! millert 368: warn("chown");
1.1 deraadt 369: (void)unlink(krbtkfile);
370: return (1);
371: }
372:
373: (void)setpriority(PRIO_PROCESS, 0, -2);
374:
375: if (gethostname(hostname, sizeof(hostname)) == -1) {
1.8 ! millert 376: warn("gethostname");
1.1 deraadt 377: dest_tkt();
378: return (1);
379: }
380:
381: (void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost));
382: savehost[sizeof(savehost) - 1] = '\0';
383:
384: kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33);
385:
386: if (kerno == KDC_PR_UNKNOWN) {
1.8 ! millert 387: warnx("Warning: TGT not verified.");
1.1 deraadt 388: syslog(LOG_NOTICE|LOG_AUTH,
389: "%s to %s%s, TGT not verified (%s); %s.%s not registered?",
390: username, user, ontty(), krb_err_txt[kerno],
391: "rcmd", savehost);
392: } else if (kerno != KSUCCESS) {
1.8 ! millert 393: warnx("Unable to use TGT: %s", krb_err_txt[kerno]);
1.1 deraadt 394: syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s",
395: username, user, ontty(), krb_err_txt[kerno]);
396: dest_tkt();
397: return (1);
398: } else {
399: if (!(hp = gethostbyname(hostname))) {
1.8 ! millert 400: warnx("can't get addr of %s", hostname);
1.1 deraadt 401: dest_tkt();
402: return (1);
403: }
404: (void)bcopy((char *)hp->h_addr, (char *)&faddr, sizeof(faddr));
405:
406: if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr,
407: &authdata, "")) != KSUCCESS) {
1.8 ! millert 408: warnx("unable to verify rcmd ticket: %s",
! 409: krb_err_txt[kerno]);
1.1 deraadt 410: syslog(LOG_NOTICE|LOG_AUTH,
411: "failed su: %s to %s%s: %s", username,
412: user, ontty(), krb_err_txt[kerno]);
413: dest_tkt();
414: return (1);
415: }
416: }
417: return (0);
418: }
419:
420: koktologin(name, realm, toname)
421: char *name, *realm, *toname;
422: {
423: register AUTH_DAT *kdata;
424: AUTH_DAT kdata_st;
425:
426: kdata = &kdata_st;
427: bzero((caddr_t) kdata, sizeof(*kdata));
428: (void)strcpy(kdata->pname, name);
429: (void)strcpy(kdata->pinst,
430: ((strcmp(toname, "root") == 0) ? "root" : ""));
431: (void)strcpy(kdata->prealm, realm);
432: return (kuserok(kdata, toname));
433: }
434: #endif
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