Annotation of src/usr.bin/doas/doas.c, Revision 1.86
1.86 ! martijn 1: /* $OpenBSD: doas.c,v 1.85 2021/01/13 13:49:34 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]"
1.47 sthen 43: " command [args]\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: {
139: int i;
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)
148: return 0;
149: return (*lastr)->action == PERMIT;
150: }
151:
152: static void
1.22 zhuk 153: parseconfig(const char *filename, int checkperms)
1.1 tedu 154: {
155: extern FILE *yyfp;
1.67 tedu 156: extern int yyparse(void);
1.6 nicm 157: struct stat sb;
1.1 tedu 158:
159: yyfp = fopen(filename, "r");
1.36 espie 160: if (!yyfp)
161: err(1, checkperms ? "doas is not enabled, %s" :
162: "could not open config file %s", filename);
1.6 nicm 163:
1.22 zhuk 164: if (checkperms) {
165: if (fstat(fileno(yyfp), &sb) != 0)
166: err(1, "fstat(\"%s\")", filename);
167: if ((sb.st_mode & (S_IWGRP|S_IWOTH)) != 0)
168: errx(1, "%s is writable by group or other", filename);
169: if (sb.st_uid != 0)
170: errx(1, "%s is not owned by root", filename);
171: }
1.6 nicm 172:
1.68 tb 173: yyparse();
1.1 tedu 174: fclose(yyfp);
1.21 zhuk 175: if (parse_errors)
176: exit(1);
1.1 tedu 177: }
178:
179: static void __dead
1.22 zhuk 180: checkconfig(const char *confpath, int argc, char **argv,
1.24 tedu 181: uid_t uid, gid_t *groups, int ngroups, uid_t target)
182: {
1.71 tedu 183: const struct rule *rule;
1.22 zhuk 184:
185: setresuid(uid, uid, uid);
1.85 kn 186: if (pledge("stdio rpath getpw", NULL) == -1)
187: err(1, "pledge");
1.22 zhuk 188: parseconfig(confpath, 0);
189: if (!argc)
190: exit(0);
191:
192: if (permit(uid, groups, ngroups, &rule, target, argv[0],
193: (const char **)argv + 1)) {
194: printf("permit%s\n", (rule->options & NOPASS) ? " nopass" : "");
1.24 tedu 195: exit(0);
1.22 zhuk 196: } else {
197: printf("deny\n");
1.24 tedu 198: exit(1);
1.22 zhuk 199: }
200: }
201:
1.61 tedu 202: static void
1.63 tedu 203: authuser(char *myname, char *login_style, int persist)
1.61 tedu 204: {
205: char *challenge = NULL, *response, rbuf[1024], cbuf[128];
206: auth_session_t *as;
1.63 tedu 207: int fd = -1;
208:
209: if (persist)
210: fd = open("/dev/tty", O_RDWR);
211: if (fd != -1) {
212: if (ioctl(fd, TIOCCHKVERAUTH) == 0)
213: goto good;
214: }
1.61 tedu 215:
216: if (!(as = auth_userchallenge(myname, login_style, "auth-doas",
217: &challenge)))
1.86 ! martijn 218: errx(1, "Authentication failed");
1.61 tedu 219: if (!challenge) {
220: char host[HOST_NAME_MAX + 1];
221: if (gethostname(host, sizeof(host)))
222: snprintf(host, sizeof(host), "?");
223: snprintf(cbuf, sizeof(cbuf),
224: "\rdoas (%.32s@%.32s) password: ", myname, host);
225: challenge = cbuf;
226: }
227: response = readpassphrase(challenge, rbuf, sizeof(rbuf),
228: RPP_REQUIRE_TTY);
229: if (response == NULL && errno == ENOTTY) {
230: syslog(LOG_AUTHPRIV | LOG_NOTICE,
231: "tty required for %s", myname);
232: errx(1, "a tty is required");
233: }
234: if (!auth_userresponse(as, response, 0)) {
1.74 tedu 235: explicit_bzero(rbuf, sizeof(rbuf));
1.61 tedu 236: syslog(LOG_AUTHPRIV | LOG_NOTICE,
237: "failed auth for %s", myname);
1.86 ! martijn 238: errx(1, "Authentication failed");
1.61 tedu 239: }
240: explicit_bzero(rbuf, sizeof(rbuf));
1.63 tedu 241: good:
242: if (fd != -1) {
1.64 tedu 243: int secs = 5 * 60;
1.63 tedu 244: ioctl(fd, TIOCSETVERAUTH, &secs);
245: close(fd);
246: }
1.61 tedu 247: }
248:
1.1 tedu 249: int
1.73 deraadt 250: unveilcommands(const char *ipath, const char *cmd)
251: {
252: char *path = NULL, *p;
253: int unveils = 0;
254:
255: if (strchr(cmd, '/') != NULL) {
256: if (unveil(cmd, "x") != -1)
257: unveils++;
258: goto done;
259: }
260:
261: if (!ipath) {
262: errno = ENOENT;
263: goto done;
264: }
265: path = strdup(ipath);
266: if (!path) {
267: errno = ENOENT;
268: goto done;
269: }
270: for (p = path; p && *p; ) {
271: char buf[PATH_MAX];
272: char *cp = strsep(&p, ":");
273:
274: if (cp) {
275: int r = snprintf(buf, sizeof buf, "%s/%s", cp, cmd);
1.80 deraadt 276: if (r >= 0 && r < sizeof buf) {
1.73 deraadt 277: if (unveil(buf, "x") != -1)
278: unveils++;
279: }
280: }
281: }
282: done:
283: free(path);
284: return (unveils);
285: }
286:
287: int
1.57 martijn 288: main(int argc, char **argv)
1.1 tedu 289: {
1.9 tedu 290: const char *safepath = "/bin:/sbin:/usr/bin:/usr/sbin:"
291: "/usr/local/bin:/usr/local/sbin";
1.22 zhuk 292: const char *confpath = NULL;
1.9 tedu 293: char *shargv[] = { NULL, NULL };
294: char *sh;
1.78 tedu 295: const char *p;
1.9 tedu 296: const char *cmd;
1.7 doug 297: char cmdline[LINE_MAX];
1.75 tedu 298: char mypwbuf[_PW_BUF_LEN], targpwbuf[_PW_BUF_LEN];
299: struct passwd mypwstore, targpwstore;
300: struct passwd *mypw, *targpw;
1.71 tedu 301: const struct rule *rule;
1.9 tedu 302: uid_t uid;
303: uid_t target = 0;
1.1 tedu 304: gid_t groups[NGROUPS_MAX + 1];
305: int ngroups;
1.75 tedu 306: int i, ch, rv;
1.8 nicm 307: int sflag = 0;
1.26 espie 308: int nflag = 0;
1.38 doug 309: char cwdpath[PATH_MAX];
310: const char *cwd;
1.47 sthen 311: char *login_style = NULL;
1.57 martijn 312: char **envp;
1.52 tedu 313:
314: setprogname("doas");
1.42 tedu 315:
316: closefrom(STDERR_FILENO + 1);
1.1 tedu 317:
1.26 espie 318: uid = getuid();
1.34 tedu 319:
1.63 tedu 320: while ((ch = getopt(argc, argv, "a:C:Lnsu:")) != -1) {
1.1 tedu 321: switch (ch) {
1.47 sthen 322: case 'a':
323: login_style = optarg;
324: break;
1.16 tedu 325: case 'C':
1.22 zhuk 326: confpath = optarg;
327: break;
1.63 tedu 328: case 'L':
329: i = open("/dev/tty", O_RDWR);
330: if (i != -1)
331: ioctl(i, TIOCCLRVERAUTH);
1.70 tedu 332: exit(i == -1);
1.1 tedu 333: case 'u':
334: if (parseuid(optarg, &target) != 0)
335: errx(1, "unknown user");
336: break;
1.26 espie 337: case 'n':
338: nflag = 1;
339: break;
1.8 nicm 340: case 's':
341: sflag = 1;
342: break;
1.1 tedu 343: default:
344: usage();
345: break;
346: }
347: }
348: argv += optind;
349: argc -= optind;
350:
1.22 zhuk 351: if (confpath) {
352: if (sflag)
353: usage();
354: } else if ((!sflag && !argc) || (sflag && argc))
1.1 tedu 355: usage();
1.16 tedu 356:
1.75 tedu 357: rv = getpwuid_r(uid, &mypwstore, mypwbuf, sizeof(mypwbuf), &mypw);
1.76 tedu 358: if (rv != 0)
1.75 tedu 359: err(1, "getpwuid_r failed");
1.76 tedu 360: if (mypw == NULL)
361: errx(1, "no passwd entry for self");
1.1 tedu 362: ngroups = getgroups(NGROUPS_MAX, groups);
363: if (ngroups == -1)
364: err(1, "can't get groups");
365: groups[ngroups++] = getgid();
1.8 nicm 366:
367: if (sflag) {
368: sh = getenv("SHELL");
1.60 zhuk 369: if (sh == NULL || *sh == '\0') {
1.76 tedu 370: shargv[0] = mypw->pw_shell;
1.60 zhuk 371: } else
1.8 nicm 372: shargv[0] = sh;
373: argv = shargv;
374: argc = 1;
375: }
1.22 zhuk 376:
1.24 tedu 377: if (confpath) {
1.85 kn 378: if (pledge("stdio rpath getpw id", NULL) == -1)
379: err(1, "pledge");
1.24 tedu 380: checkconfig(confpath, argc, argv, uid, groups, ngroups,
381: target);
382: exit(1); /* fail safe */
383: }
1.69 tedu 384:
385: if (geteuid())
386: errx(1, "not installed setuid");
1.24 tedu 387:
1.22 zhuk 388: parseconfig("/etc/doas.conf", 1);
1.8 nicm 389:
1.23 zhuk 390: /* cmdline is used only for logging, no need to abort on truncate */
1.58 tedu 391: (void)strlcpy(cmdline, argv[0], sizeof(cmdline));
1.8 nicm 392: for (i = 1; i < argc; i++) {
393: if (strlcat(cmdline, " ", sizeof(cmdline)) >= sizeof(cmdline))
1.23 zhuk 394: break;
1.8 nicm 395: if (strlcat(cmdline, argv[i], sizeof(cmdline)) >= sizeof(cmdline))
1.23 zhuk 396: break;
1.8 nicm 397: }
1.1 tedu 398:
1.23 zhuk 399: cmd = argv[0];
1.15 zhuk 400: if (!permit(uid, groups, ngroups, &rule, target, cmd,
1.58 tedu 401: (const char **)argv + 1)) {
1.4 deraadt 402: syslog(LOG_AUTHPRIV | LOG_NOTICE,
1.83 kn 403: "command not permitted for %s: %s", mypw->pw_name, cmdline);
1.41 tedu 404: errc(1, EPERM, NULL);
1.1 tedu 405: }
406:
407: if (!(rule->options & NOPASS)) {
1.26 espie 408: if (nflag)
1.86 ! martijn 409: errx(1, "Authentication required");
1.46 tedu 410:
1.76 tedu 411: authuser(mypw->pw_name, login_style, rule->options & PERSIST);
1.1 tedu 412: }
1.78 tedu 413:
414: if ((p = getenv("PATH")) != NULL)
415: formerpath = strdup(p);
416: if (formerpath == NULL)
417: formerpath = "";
1.43 deraadt 418:
1.81 semarie 419: if (unveil(_PATH_LOGIN_CONF, "r") == -1 ||
420: unveil(_PATH_LOGIN_CONF ".db", "r") == -1)
1.73 deraadt 421: err(1, "unveil");
422: if (rule->cmd) {
423: if (setenv("PATH", safepath, 1) == -1)
424: err(1, "failed to set PATH '%s'", safepath);
425: }
426: if (unveilcommands(getenv("PATH"), cmd) == 0)
427: goto fail;
428:
1.43 deraadt 429: if (pledge("stdio rpath getpw exec id", NULL) == -1)
430: err(1, "pledge");
431:
1.75 tedu 432: rv = getpwuid_r(target, &targpwstore, targpwbuf, sizeof(targpwbuf), &targpw);
1.76 tedu 433: if (rv != 0)
434: err(1, "getpwuid_r failed");
435: if (targpw == NULL)
1.1 tedu 436: errx(1, "no passwd entry for target");
1.43 deraadt 437:
1.75 tedu 438: if (setusercontext(NULL, targpw, target, LOGIN_SETGROUP |
1.77 tedu 439: LOGIN_SETPATH |
1.1 tedu 440: LOGIN_SETPRIORITY | LOGIN_SETRESOURCES | LOGIN_SETUMASK |
441: LOGIN_SETUSER) != 0)
442: errx(1, "failed to set user context for target");
443:
1.43 deraadt 444: if (pledge("stdio rpath exec", NULL) == -1)
445: err(1, "pledge");
446:
1.38 doug 447: if (getcwd(cwdpath, sizeof(cwdpath)) == NULL)
448: cwd = "(failed)";
449: else
450: cwd = cwdpath;
1.43 deraadt 451:
452: if (pledge("stdio exec", NULL) == -1)
453: err(1, "pledge");
1.38 doug 454:
1.84 kn 455: if (!(rule->options & NOLOG)) {
456: syslog(LOG_AUTHPRIV | LOG_INFO,
457: "%s ran command %s as %s from %s",
458: mypw->pw_name, cmdline, targpw->pw_name, cwd);
459: }
1.44 tedu 460:
1.77 tedu 461: envp = prepenv(rule, mypw, targpw);
1.38 doug 462:
1.79 tedu 463: /* setusercontext set path for the next process, so reset it for us */
1.77 tedu 464: if (rule->cmd) {
465: if (setenv("PATH", safepath, 1) == -1)
466: err(1, "failed to set PATH '%s'", safepath);
1.79 tedu 467: } else {
468: if (setenv("PATH", formerpath, 1) == -1)
469: err(1, "failed to set PATH '%s'", formerpath);
1.77 tedu 470: }
1.1 tedu 471: execvpe(cmd, argv, envp);
1.73 deraadt 472: fail:
1.10 tedu 473: if (errno == ENOENT)
474: errx(1, "%s: command not found", cmd);
1.1 tedu 475: err(1, "%s", cmd);
476: }