Annotation of src/usr.bin/doas/doas.c, Revision 1.87
1.87 ! kn 1: /* $OpenBSD: doas.c,v 1.86 2021/01/16 09:18:41 martijn 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:
1.87 ! kn 209: if (persist) {
1.63 tedu 210: fd = open("/dev/tty", O_RDWR);
1.87 ! kn 211: if (fd != -1) {
! 212: if (ioctl(fd, TIOCCHKVERAUTH) == 0)
! 213: goto good;
! 214: }
! 215: } else {
! 216: if (pledge("stdio rpath getpw exec id unveil", NULL) == -1)
! 217: err(1, "pledge");
1.63 tedu 218: }
1.61 tedu 219:
220: if (!(as = auth_userchallenge(myname, login_style, "auth-doas",
221: &challenge)))
1.86 martijn 222: errx(1, "Authentication failed");
1.61 tedu 223: if (!challenge) {
224: char host[HOST_NAME_MAX + 1];
225: if (gethostname(host, sizeof(host)))
226: snprintf(host, sizeof(host), "?");
227: snprintf(cbuf, sizeof(cbuf),
228: "\rdoas (%.32s@%.32s) password: ", myname, host);
229: challenge = cbuf;
230: }
231: response = readpassphrase(challenge, rbuf, sizeof(rbuf),
232: RPP_REQUIRE_TTY);
233: if (response == NULL && errno == ENOTTY) {
234: syslog(LOG_AUTHPRIV | LOG_NOTICE,
235: "tty required for %s", myname);
236: errx(1, "a tty is required");
237: }
238: if (!auth_userresponse(as, response, 0)) {
1.74 tedu 239: explicit_bzero(rbuf, sizeof(rbuf));
1.61 tedu 240: syslog(LOG_AUTHPRIV | LOG_NOTICE,
241: "failed auth for %s", myname);
1.86 martijn 242: errx(1, "Authentication failed");
1.61 tedu 243: }
244: explicit_bzero(rbuf, sizeof(rbuf));
1.63 tedu 245: good:
246: if (fd != -1) {
1.64 tedu 247: int secs = 5 * 60;
1.63 tedu 248: ioctl(fd, TIOCSETVERAUTH, &secs);
249: close(fd);
250: }
1.61 tedu 251: }
252:
1.1 tedu 253: int
1.73 deraadt 254: unveilcommands(const char *ipath, const char *cmd)
255: {
256: char *path = NULL, *p;
257: int unveils = 0;
258:
259: if (strchr(cmd, '/') != NULL) {
260: if (unveil(cmd, "x") != -1)
261: unveils++;
262: goto done;
263: }
264:
265: if (!ipath) {
266: errno = ENOENT;
267: goto done;
268: }
269: path = strdup(ipath);
270: if (!path) {
271: errno = ENOENT;
272: goto done;
273: }
274: for (p = path; p && *p; ) {
275: char buf[PATH_MAX];
276: char *cp = strsep(&p, ":");
277:
278: if (cp) {
279: int r = snprintf(buf, sizeof buf, "%s/%s", cp, cmd);
1.80 deraadt 280: if (r >= 0 && r < sizeof buf) {
1.73 deraadt 281: if (unveil(buf, "x") != -1)
282: unveils++;
283: }
284: }
285: }
286: done:
287: free(path);
288: return (unveils);
289: }
290:
291: int
1.57 martijn 292: main(int argc, char **argv)
1.1 tedu 293: {
1.9 tedu 294: const char *safepath = "/bin:/sbin:/usr/bin:/usr/sbin:"
295: "/usr/local/bin:/usr/local/sbin";
1.22 zhuk 296: const char *confpath = NULL;
1.9 tedu 297: char *shargv[] = { NULL, NULL };
298: char *sh;
1.78 tedu 299: const char *p;
1.9 tedu 300: const char *cmd;
1.7 doug 301: char cmdline[LINE_MAX];
1.75 tedu 302: char mypwbuf[_PW_BUF_LEN], targpwbuf[_PW_BUF_LEN];
303: struct passwd mypwstore, targpwstore;
304: struct passwd *mypw, *targpw;
1.71 tedu 305: const struct rule *rule;
1.9 tedu 306: uid_t uid;
307: uid_t target = 0;
1.1 tedu 308: gid_t groups[NGROUPS_MAX + 1];
309: int ngroups;
1.75 tedu 310: int i, ch, rv;
1.8 nicm 311: int sflag = 0;
1.26 espie 312: int nflag = 0;
1.38 doug 313: char cwdpath[PATH_MAX];
314: const char *cwd;
1.47 sthen 315: char *login_style = NULL;
1.57 martijn 316: char **envp;
1.52 tedu 317:
318: setprogname("doas");
1.42 tedu 319:
320: closefrom(STDERR_FILENO + 1);
1.1 tedu 321:
1.26 espie 322: uid = getuid();
1.34 tedu 323:
1.63 tedu 324: while ((ch = getopt(argc, argv, "a:C:Lnsu:")) != -1) {
1.1 tedu 325: switch (ch) {
1.47 sthen 326: case 'a':
327: login_style = optarg;
328: break;
1.16 tedu 329: case 'C':
1.22 zhuk 330: confpath = optarg;
331: break;
1.63 tedu 332: case 'L':
333: i = open("/dev/tty", O_RDWR);
334: if (i != -1)
335: ioctl(i, TIOCCLRVERAUTH);
1.70 tedu 336: exit(i == -1);
1.1 tedu 337: case 'u':
338: if (parseuid(optarg, &target) != 0)
339: errx(1, "unknown user");
340: break;
1.26 espie 341: case 'n':
342: nflag = 1;
343: break;
1.8 nicm 344: case 's':
345: sflag = 1;
346: break;
1.1 tedu 347: default:
348: usage();
349: break;
350: }
351: }
352: argv += optind;
353: argc -= optind;
354:
1.22 zhuk 355: if (confpath) {
356: if (sflag)
357: usage();
358: } else if ((!sflag && !argc) || (sflag && argc))
1.1 tedu 359: usage();
1.16 tedu 360:
1.75 tedu 361: rv = getpwuid_r(uid, &mypwstore, mypwbuf, sizeof(mypwbuf), &mypw);
1.76 tedu 362: if (rv != 0)
1.75 tedu 363: err(1, "getpwuid_r failed");
1.76 tedu 364: if (mypw == NULL)
365: errx(1, "no passwd entry for self");
1.1 tedu 366: ngroups = getgroups(NGROUPS_MAX, groups);
367: if (ngroups == -1)
368: err(1, "can't get groups");
369: groups[ngroups++] = getgid();
1.8 nicm 370:
371: if (sflag) {
372: sh = getenv("SHELL");
1.60 zhuk 373: if (sh == NULL || *sh == '\0') {
1.76 tedu 374: shargv[0] = mypw->pw_shell;
1.60 zhuk 375: } else
1.8 nicm 376: shargv[0] = sh;
377: argv = shargv;
378: argc = 1;
379: }
1.22 zhuk 380:
1.24 tedu 381: if (confpath) {
1.85 kn 382: if (pledge("stdio rpath getpw id", NULL) == -1)
383: err(1, "pledge");
1.24 tedu 384: checkconfig(confpath, argc, argv, uid, groups, ngroups,
385: target);
386: exit(1); /* fail safe */
387: }
1.69 tedu 388:
389: if (geteuid())
390: errx(1, "not installed setuid");
1.24 tedu 391:
1.22 zhuk 392: parseconfig("/etc/doas.conf", 1);
1.8 nicm 393:
1.23 zhuk 394: /* cmdline is used only for logging, no need to abort on truncate */
1.58 tedu 395: (void)strlcpy(cmdline, argv[0], sizeof(cmdline));
1.8 nicm 396: for (i = 1; i < argc; i++) {
397: if (strlcat(cmdline, " ", sizeof(cmdline)) >= sizeof(cmdline))
1.23 zhuk 398: break;
1.8 nicm 399: if (strlcat(cmdline, argv[i], sizeof(cmdline)) >= sizeof(cmdline))
1.23 zhuk 400: break;
1.8 nicm 401: }
1.1 tedu 402:
1.23 zhuk 403: cmd = argv[0];
1.15 zhuk 404: if (!permit(uid, groups, ngroups, &rule, target, cmd,
1.58 tedu 405: (const char **)argv + 1)) {
1.4 deraadt 406: syslog(LOG_AUTHPRIV | LOG_NOTICE,
1.83 kn 407: "command not permitted for %s: %s", mypw->pw_name, cmdline);
1.41 tedu 408: errc(1, EPERM, NULL);
1.1 tedu 409: }
410:
411: if (!(rule->options & NOPASS)) {
1.26 espie 412: if (nflag)
1.86 martijn 413: errx(1, "Authentication required");
1.46 tedu 414:
1.76 tedu 415: authuser(mypw->pw_name, login_style, rule->options & PERSIST);
1.1 tedu 416: }
1.78 tedu 417:
418: if ((p = getenv("PATH")) != NULL)
419: formerpath = strdup(p);
420: if (formerpath == NULL)
421: formerpath = "";
1.43 deraadt 422:
1.81 semarie 423: if (unveil(_PATH_LOGIN_CONF, "r") == -1 ||
424: unveil(_PATH_LOGIN_CONF ".db", "r") == -1)
1.73 deraadt 425: err(1, "unveil");
426: if (rule->cmd) {
427: if (setenv("PATH", safepath, 1) == -1)
428: err(1, "failed to set PATH '%s'", safepath);
429: }
430: if (unveilcommands(getenv("PATH"), cmd) == 0)
431: goto fail;
432:
1.43 deraadt 433: if (pledge("stdio rpath getpw exec id", NULL) == -1)
434: err(1, "pledge");
435:
1.75 tedu 436: rv = getpwuid_r(target, &targpwstore, targpwbuf, sizeof(targpwbuf), &targpw);
1.76 tedu 437: if (rv != 0)
438: err(1, "getpwuid_r failed");
439: if (targpw == NULL)
1.1 tedu 440: errx(1, "no passwd entry for target");
1.43 deraadt 441:
1.75 tedu 442: if (setusercontext(NULL, targpw, target, LOGIN_SETGROUP |
1.77 tedu 443: LOGIN_SETPATH |
1.1 tedu 444: LOGIN_SETPRIORITY | LOGIN_SETRESOURCES | LOGIN_SETUMASK |
445: LOGIN_SETUSER) != 0)
446: errx(1, "failed to set user context for target");
447:
1.43 deraadt 448: if (pledge("stdio rpath exec", NULL) == -1)
449: err(1, "pledge");
450:
1.38 doug 451: if (getcwd(cwdpath, sizeof(cwdpath)) == NULL)
452: cwd = "(failed)";
453: else
454: cwd = cwdpath;
1.43 deraadt 455:
456: if (pledge("stdio exec", NULL) == -1)
457: err(1, "pledge");
1.38 doug 458:
1.84 kn 459: if (!(rule->options & NOLOG)) {
460: syslog(LOG_AUTHPRIV | LOG_INFO,
461: "%s ran command %s as %s from %s",
462: mypw->pw_name, cmdline, targpw->pw_name, cwd);
463: }
1.44 tedu 464:
1.77 tedu 465: envp = prepenv(rule, mypw, targpw);
1.38 doug 466:
1.79 tedu 467: /* setusercontext set path for the next process, so reset it for us */
1.77 tedu 468: if (rule->cmd) {
469: if (setenv("PATH", safepath, 1) == -1)
470: err(1, "failed to set PATH '%s'", safepath);
1.79 tedu 471: } else {
472: if (setenv("PATH", formerpath, 1) == -1)
473: err(1, "failed to set PATH '%s'", formerpath);
1.77 tedu 474: }
1.1 tedu 475: execvpe(cmd, argv, envp);
1.73 deraadt 476: fail:
1.10 tedu 477: if (errno == ENOENT)
478: errx(1, "%s: command not found", cmd);
1.1 tedu 479: err(1, "%s", cmd);
480: }
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