Annotation of src/usr.bin/doas/doas.c, Revision 1.99
1.99 ! tedu 1: /* $OpenBSD: doas.c,v 1.98 2022/12/22 19:53:22 kn Exp $ */
1.1 tedu 2: /*
3: * Copyright (c) 2015 Ted Unangst <tedu@openbsd.org>
4: *
5: * Permission to use, copy, modify, and distribute this software for any
6: * purpose with or without fee is hereby granted, provided that the above
7: * copyright notice and this permission notice appear in all copies.
8: *
9: * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10: * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11: * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12: * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13: * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14: * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15: * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16: */
1.6 nicm 17:
1.1 tedu 18: #include <sys/types.h>
1.6 nicm 19: #include <sys/stat.h>
1.63 tedu 20: #include <sys/ioctl.h>
1.1 tedu 21:
22: #include <limits.h>
23: #include <login_cap.h>
24: #include <bsd_auth.h>
1.46 tedu 25: #include <readpassphrase.h>
1.1 tedu 26: #include <string.h>
27: #include <stdio.h>
28: #include <stdlib.h>
29: #include <err.h>
30: #include <unistd.h>
31: #include <pwd.h>
32: #include <grp.h>
33: #include <syslog.h>
1.10 tedu 34: #include <errno.h>
1.63 tedu 35: #include <fcntl.h>
1.1 tedu 36:
37: #include "doas.h"
38:
39: static void __dead
40: usage(void)
41: {
1.63 tedu 42: fprintf(stderr, "usage: doas [-Lns] [-a style] [-C config] [-u user]"
1.98 kn 43: " command [arg ...]\n");
1.1 tedu 44: exit(1);
45: }
46:
47: static int
48: parseuid(const char *s, uid_t *uid)
49: {
50: struct passwd *pw;
51: const char *errstr;
52:
53: if ((pw = getpwnam(s)) != NULL) {
54: *uid = pw->pw_uid;
1.82 tedu 55: if (*uid == UID_MAX)
56: return -1;
1.1 tedu 57: return 0;
58: }
1.82 tedu 59: *uid = strtonum(s, 0, UID_MAX - 1, &errstr);
1.1 tedu 60: if (errstr)
61: return -1;
62: return 0;
63: }
64:
65: static int
66: uidcheck(const char *s, uid_t desired)
67: {
68: uid_t uid;
69:
70: if (parseuid(s, &uid) != 0)
71: return -1;
72: if (uid != desired)
73: return -1;
74: return 0;
75: }
76:
1.33 tedu 77: static int
78: parsegid(const char *s, gid_t *gid)
1.1 tedu 79: {
80: struct group *gr;
81: const char *errstr;
82:
1.33 tedu 83: if ((gr = getgrnam(s)) != NULL) {
84: *gid = gr->gr_gid;
1.82 tedu 85: if (*gid == GID_MAX)
86: return -1;
1.33 tedu 87: return 0;
88: }
1.82 tedu 89: *gid = strtonum(s, 0, GID_MAX - 1, &errstr);
1.1 tedu 90: if (errstr)
91: return -1;
1.33 tedu 92: return 0;
1.1 tedu 93: }
94:
95: static int
96: match(uid_t uid, gid_t *groups, int ngroups, uid_t target, const char *cmd,
1.15 zhuk 97: const char **cmdargs, struct rule *r)
1.1 tedu 98: {
99: int i;
100:
101: if (r->ident[0] == ':') {
1.33 tedu 102: gid_t rgid;
103: if (parsegid(r->ident + 1, &rgid) == -1)
1.1 tedu 104: return 0;
105: for (i = 0; i < ngroups; i++) {
106: if (rgid == groups[i])
107: break;
108: }
109: if (i == ngroups)
110: return 0;
111: } else {
112: if (uidcheck(r->ident, uid) != 0)
113: return 0;
114: }
115: if (r->target && uidcheck(r->target, target) != 0)
116: return 0;
1.15 zhuk 117: if (r->cmd) {
118: if (strcmp(r->cmd, cmd))
119: return 0;
120: if (r->cmdargs) {
121: /* if arguments were given, they should match explicitly */
122: for (i = 0; r->cmdargs[i]; i++) {
123: if (!cmdargs[i])
124: return 0;
125: if (strcmp(r->cmdargs[i], cmdargs[i]))
126: return 0;
127: }
128: if (cmdargs[i])
129: return 0;
130: }
131: }
1.1 tedu 132: return 1;
133: }
134:
135: static int
1.71 tedu 136: permit(uid_t uid, gid_t *groups, int ngroups, const struct rule **lastr,
1.15 zhuk 137: uid_t target, const char *cmd, const char **cmdargs)
1.1 tedu 138: {
1.89 millert 139: size_t i;
1.1 tedu 140:
141: *lastr = NULL;
142: for (i = 0; i < nrules; i++) {
1.31 deraadt 143: if (match(uid, groups, ngroups, target, cmd,
144: cmdargs, rules[i]))
1.1 tedu 145: *lastr = rules[i];
146: }
147: if (!*lastr)
1.99 ! tedu 148: return -1;
! 149: if ((*lastr)->action == PERMIT)
1.1 tedu 150: return 0;
1.99 ! tedu 151: return -1;
1.1 tedu 152: }
153:
154: static void
1.22 zhuk 155: parseconfig(const char *filename, int checkperms)
1.1 tedu 156: {
157: extern FILE *yyfp;
1.67 tedu 158: extern int yyparse(void);
1.6 nicm 159: struct stat sb;
1.1 tedu 160:
161: yyfp = fopen(filename, "r");
1.36 espie 162: if (!yyfp)
163: err(1, checkperms ? "doas is not enabled, %s" :
164: "could not open config file %s", filename);
1.6 nicm 165:
1.22 zhuk 166: if (checkperms) {
167: if (fstat(fileno(yyfp), &sb) != 0)
168: err(1, "fstat(\"%s\")", filename);
169: if ((sb.st_mode & (S_IWGRP|S_IWOTH)) != 0)
170: errx(1, "%s is writable by group or other", filename);
171: if (sb.st_uid != 0)
172: errx(1, "%s is not owned by root", filename);
173: }
1.6 nicm 174:
1.68 tb 175: yyparse();
1.1 tedu 176: fclose(yyfp);
1.93 tobias 177: if (parse_error)
1.21 zhuk 178: exit(1);
1.1 tedu 179: }
180:
181: static void __dead
1.22 zhuk 182: checkconfig(const char *confpath, int argc, char **argv,
1.24 tedu 183: uid_t uid, gid_t *groups, int ngroups, uid_t target)
184: {
1.71 tedu 185: const struct rule *rule;
1.99 ! tedu 186: int rv;
1.22 zhuk 187:
188: setresuid(uid, uid, uid);
1.85 kn 189: if (pledge("stdio rpath getpw", NULL) == -1)
190: err(1, "pledge");
1.22 zhuk 191: parseconfig(confpath, 0);
192: if (!argc)
193: exit(0);
1.99 ! tedu 194: rv = permit(uid, groups, ngroups, &rule, target, argv[0],
! 195: (const char **)argv + 1);
! 196: if (rv == 0) {
1.22 zhuk 197: printf("permit%s\n", (rule->options & NOPASS) ? " nopass" : "");
1.24 tedu 198: exit(0);
1.22 zhuk 199: } else {
200: printf("deny\n");
1.24 tedu 201: exit(1);
1.22 zhuk 202: }
203: }
204:
1.91 jcs 205: static int
1.92 millert 206: authuser_checkpass(char *myname, char *login_style)
1.61 tedu 207: {
208: char *challenge = NULL, *response, rbuf[1024], cbuf[128];
209: auth_session_t *as;
210:
211: if (!(as = auth_userchallenge(myname, login_style, "auth-doas",
1.91 jcs 212: &challenge))) {
213: warnx("Authentication failed");
214: return AUTH_FAILED;
215: }
1.61 tedu 216: if (!challenge) {
217: char host[HOST_NAME_MAX + 1];
1.97 deraadt 218:
1.61 tedu 219: if (gethostname(host, sizeof(host)))
220: snprintf(host, sizeof(host), "?");
221: snprintf(cbuf, sizeof(cbuf),
222: "\rdoas (%.32s@%.32s) password: ", myname, host);
223: challenge = cbuf;
224: }
225: response = readpassphrase(challenge, rbuf, sizeof(rbuf),
226: RPP_REQUIRE_TTY);
227: if (response == NULL && errno == ENOTTY) {
228: syslog(LOG_AUTHPRIV | LOG_NOTICE,
229: "tty required for %s", myname);
230: errx(1, "a tty is required");
231: }
232: if (!auth_userresponse(as, response, 0)) {
1.74 tedu 233: explicit_bzero(rbuf, sizeof(rbuf));
1.61 tedu 234: syslog(LOG_AUTHPRIV | LOG_NOTICE,
235: "failed auth for %s", myname);
1.91 jcs 236: warnx("Authentication failed");
237: return AUTH_FAILED;
1.61 tedu 238: }
239: explicit_bzero(rbuf, sizeof(rbuf));
1.92 millert 240: return AUTH_OK;
241: }
242:
243: static void
244: authuser(char *myname, char *login_style, int persist)
245: {
246: int i, fd = -1;
247:
248: if (persist)
249: fd = open("/dev/tty", O_RDWR);
250: if (fd != -1) {
251: if (ioctl(fd, TIOCCHKVERAUTH) == 0)
252: goto good;
253: }
254: for (i = 0; i < AUTH_RETRIES; i++) {
255: if (authuser_checkpass(myname, login_style) == AUTH_OK)
256: goto good;
257: }
258: exit(1);
1.63 tedu 259: good:
260: if (fd != -1) {
1.64 tedu 261: int secs = 5 * 60;
1.63 tedu 262: ioctl(fd, TIOCSETVERAUTH, &secs);
263: close(fd);
264: }
1.61 tedu 265: }
266:
1.1 tedu 267: int
1.73 deraadt 268: unveilcommands(const char *ipath, const char *cmd)
269: {
270: char *path = NULL, *p;
271: int unveils = 0;
272:
273: if (strchr(cmd, '/') != NULL) {
274: if (unveil(cmd, "x") != -1)
275: unveils++;
276: goto done;
277: }
278:
279: if (!ipath) {
280: errno = ENOENT;
281: goto done;
282: }
283: path = strdup(ipath);
284: if (!path) {
285: errno = ENOENT;
286: goto done;
287: }
288: for (p = path; p && *p; ) {
289: char buf[PATH_MAX];
290: char *cp = strsep(&p, ":");
291:
292: if (cp) {
293: int r = snprintf(buf, sizeof buf, "%s/%s", cp, cmd);
1.80 deraadt 294: if (r >= 0 && r < sizeof buf) {
1.73 deraadt 295: if (unveil(buf, "x") != -1)
296: unveils++;
297: }
298: }
299: }
300: done:
301: free(path);
302: return (unveils);
303: }
304:
305: int
1.57 martijn 306: main(int argc, char **argv)
1.1 tedu 307: {
1.9 tedu 308: const char *safepath = "/bin:/sbin:/usr/bin:/usr/sbin:"
309: "/usr/local/bin:/usr/local/sbin";
1.22 zhuk 310: const char *confpath = NULL;
1.9 tedu 311: char *shargv[] = { NULL, NULL };
312: char *sh;
1.78 tedu 313: const char *p;
1.9 tedu 314: const char *cmd;
1.7 doug 315: char cmdline[LINE_MAX];
1.75 tedu 316: char mypwbuf[_PW_BUF_LEN], targpwbuf[_PW_BUF_LEN];
317: struct passwd mypwstore, targpwstore;
318: struct passwd *mypw, *targpw;
1.71 tedu 319: const struct rule *rule;
1.9 tedu 320: uid_t uid;
321: uid_t target = 0;
1.1 tedu 322: gid_t groups[NGROUPS_MAX + 1];
323: int ngroups;
1.75 tedu 324: int i, ch, rv;
1.8 nicm 325: int sflag = 0;
1.26 espie 326: int nflag = 0;
1.38 doug 327: char cwdpath[PATH_MAX];
328: const char *cwd;
1.47 sthen 329: char *login_style = NULL;
1.57 martijn 330: char **envp;
1.52 tedu 331:
332: setprogname("doas");
1.42 tedu 333:
334: closefrom(STDERR_FILENO + 1);
1.1 tedu 335:
1.26 espie 336: uid = getuid();
1.34 tedu 337:
1.63 tedu 338: while ((ch = getopt(argc, argv, "a:C:Lnsu:")) != -1) {
1.1 tedu 339: switch (ch) {
1.47 sthen 340: case 'a':
341: login_style = optarg;
342: break;
1.16 tedu 343: case 'C':
1.22 zhuk 344: confpath = optarg;
345: break;
1.63 tedu 346: case 'L':
347: i = open("/dev/tty", O_RDWR);
348: if (i != -1)
349: ioctl(i, TIOCCLRVERAUTH);
1.70 tedu 350: exit(i == -1);
1.1 tedu 351: case 'u':
352: if (parseuid(optarg, &target) != 0)
353: errx(1, "unknown user");
354: break;
1.26 espie 355: case 'n':
356: nflag = 1;
357: break;
1.8 nicm 358: case 's':
359: sflag = 1;
360: break;
1.1 tedu 361: default:
362: usage();
363: break;
364: }
365: }
366: argv += optind;
367: argc -= optind;
368:
1.22 zhuk 369: if (confpath) {
370: if (sflag)
371: usage();
372: } else if ((!sflag && !argc) || (sflag && argc))
1.1 tedu 373: usage();
1.16 tedu 374:
1.75 tedu 375: rv = getpwuid_r(uid, &mypwstore, mypwbuf, sizeof(mypwbuf), &mypw);
1.76 tedu 376: if (rv != 0)
1.75 tedu 377: err(1, "getpwuid_r failed");
1.76 tedu 378: if (mypw == NULL)
379: errx(1, "no passwd entry for self");
1.1 tedu 380: ngroups = getgroups(NGROUPS_MAX, groups);
381: if (ngroups == -1)
382: err(1, "can't get groups");
383: groups[ngroups++] = getgid();
1.8 nicm 384:
385: if (sflag) {
386: sh = getenv("SHELL");
1.60 zhuk 387: if (sh == NULL || *sh == '\0') {
1.76 tedu 388: shargv[0] = mypw->pw_shell;
1.60 zhuk 389: } else
1.8 nicm 390: shargv[0] = sh;
391: argv = shargv;
392: argc = 1;
393: }
1.22 zhuk 394:
1.24 tedu 395: if (confpath) {
1.85 kn 396: if (pledge("stdio rpath getpw id", NULL) == -1)
397: err(1, "pledge");
1.24 tedu 398: checkconfig(confpath, argc, argv, uid, groups, ngroups,
399: target);
400: exit(1); /* fail safe */
401: }
1.69 tedu 402:
403: if (geteuid())
404: errx(1, "not installed setuid");
1.24 tedu 405:
1.22 zhuk 406: parseconfig("/etc/doas.conf", 1);
1.8 nicm 407:
1.23 zhuk 408: /* cmdline is used only for logging, no need to abort on truncate */
1.58 tedu 409: (void)strlcpy(cmdline, argv[0], sizeof(cmdline));
1.8 nicm 410: for (i = 1; i < argc; i++) {
411: if (strlcat(cmdline, " ", sizeof(cmdline)) >= sizeof(cmdline))
1.23 zhuk 412: break;
1.8 nicm 413: if (strlcat(cmdline, argv[i], sizeof(cmdline)) >= sizeof(cmdline))
1.23 zhuk 414: break;
1.8 nicm 415: }
1.1 tedu 416:
1.23 zhuk 417: cmd = argv[0];
1.99 ! tedu 418: rv = permit(uid, groups, ngroups, &rule, target, cmd,
! 419: (const char **)argv + 1);
! 420: if (rv != 0) {
1.4 deraadt 421: syslog(LOG_AUTHPRIV | LOG_NOTICE,
1.83 kn 422: "command not permitted for %s: %s", mypw->pw_name, cmdline);
1.41 tedu 423: errc(1, EPERM, NULL);
1.1 tedu 424: }
425:
426: if (!(rule->options & NOPASS)) {
1.26 espie 427: if (nflag)
1.86 martijn 428: errx(1, "Authentication required");
1.46 tedu 429:
1.92 millert 430: authuser(mypw->pw_name, login_style, rule->options & PERSIST);
1.1 tedu 431: }
1.78 tedu 432:
433: if ((p = getenv("PATH")) != NULL)
434: formerpath = strdup(p);
435: if (formerpath == NULL)
436: formerpath = "";
1.43 deraadt 437:
1.90 beck 438: if (unveil(_PATH_LOGIN_CONF, "r") == -1)
439: err(1, "unveil %s", _PATH_LOGIN_CONF);
440: if (unveil(_PATH_LOGIN_CONF ".db", "r") == -1)
441: err(1, "unveil %s.db", _PATH_LOGIN_CONF);
1.94 robert 442: if (unveil(_PATH_LOGIN_CONF_D, "r") == -1)
443: err(1, "unveil %s", _PATH_LOGIN_CONF_D);
1.73 deraadt 444: if (rule->cmd) {
445: if (setenv("PATH", safepath, 1) == -1)
446: err(1, "failed to set PATH '%s'", safepath);
447: }
448: if (unveilcommands(getenv("PATH"), cmd) == 0)
449: goto fail;
450:
1.43 deraadt 451: if (pledge("stdio rpath getpw exec id", NULL) == -1)
452: err(1, "pledge");
453:
1.75 tedu 454: rv = getpwuid_r(target, &targpwstore, targpwbuf, sizeof(targpwbuf), &targpw);
1.76 tedu 455: if (rv != 0)
456: err(1, "getpwuid_r failed");
457: if (targpw == NULL)
1.1 tedu 458: errx(1, "no passwd entry for target");
1.43 deraadt 459:
1.96 tb 460: if (setusercontext(NULL, targpw, target, LOGIN_SETGROUP |
461: LOGIN_SETPATH |
462: LOGIN_SETPRIORITY | LOGIN_SETRESOURCES | LOGIN_SETUMASK |
463: LOGIN_SETUSER | LOGIN_SETENV | LOGIN_SETRTABLE) != 0)
1.1 tedu 464: errx(1, "failed to set user context for target");
465:
1.43 deraadt 466: if (pledge("stdio rpath exec", NULL) == -1)
467: err(1, "pledge");
468:
1.38 doug 469: if (getcwd(cwdpath, sizeof(cwdpath)) == NULL)
470: cwd = "(failed)";
471: else
472: cwd = cwdpath;
1.43 deraadt 473:
474: if (pledge("stdio exec", NULL) == -1)
475: err(1, "pledge");
1.38 doug 476:
1.84 kn 477: if (!(rule->options & NOLOG)) {
478: syslog(LOG_AUTHPRIV | LOG_INFO,
479: "%s ran command %s as %s from %s",
480: mypw->pw_name, cmdline, targpw->pw_name, cwd);
481: }
1.44 tedu 482:
1.77 tedu 483: envp = prepenv(rule, mypw, targpw);
1.38 doug 484:
1.79 tedu 485: /* setusercontext set path for the next process, so reset it for us */
1.77 tedu 486: if (rule->cmd) {
487: if (setenv("PATH", safepath, 1) == -1)
488: err(1, "failed to set PATH '%s'", safepath);
1.79 tedu 489: } else {
490: if (setenv("PATH", formerpath, 1) == -1)
491: err(1, "failed to set PATH '%s'", formerpath);
1.77 tedu 492: }
1.1 tedu 493: execvpe(cmd, argv, envp);
1.73 deraadt 494: fail:
1.10 tedu 495: if (errno == ENOENT)
496: errx(1, "%s: command not found", cmd);
1.1 tedu 497: err(1, "%s", cmd);
498: }
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