Annotation of src/usr.bin/doas/doas.c, Revision 1.77
1.77 ! tedu 1: /* $OpenBSD: doas.c,v 1.76 2019/06/12 02:50:29 tedu 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;
55: return 0;
56: }
57: *uid = strtonum(s, 0, UID_MAX, &errstr);
58: if (errstr)
59: return -1;
60: return 0;
61: }
62:
63: static int
64: uidcheck(const char *s, uid_t desired)
65: {
66: uid_t uid;
67:
68: if (parseuid(s, &uid) != 0)
69: return -1;
70: if (uid != desired)
71: return -1;
72: return 0;
73: }
74:
1.33 tedu 75: static int
76: parsegid(const char *s, gid_t *gid)
1.1 tedu 77: {
78: struct group *gr;
79: const char *errstr;
80:
1.33 tedu 81: if ((gr = getgrnam(s)) != NULL) {
82: *gid = gr->gr_gid;
83: return 0;
84: }
85: *gid = strtonum(s, 0, GID_MAX, &errstr);
1.1 tedu 86: if (errstr)
87: return -1;
1.33 tedu 88: return 0;
1.1 tedu 89: }
90:
91: static int
92: match(uid_t uid, gid_t *groups, int ngroups, uid_t target, const char *cmd,
1.15 zhuk 93: const char **cmdargs, struct rule *r)
1.1 tedu 94: {
95: int i;
96:
97: if (r->ident[0] == ':') {
1.33 tedu 98: gid_t rgid;
99: if (parsegid(r->ident + 1, &rgid) == -1)
1.1 tedu 100: return 0;
101: for (i = 0; i < ngroups; i++) {
102: if (rgid == groups[i])
103: break;
104: }
105: if (i == ngroups)
106: return 0;
107: } else {
108: if (uidcheck(r->ident, uid) != 0)
109: return 0;
110: }
111: if (r->target && uidcheck(r->target, target) != 0)
112: return 0;
1.15 zhuk 113: if (r->cmd) {
114: if (strcmp(r->cmd, cmd))
115: return 0;
116: if (r->cmdargs) {
117: /* if arguments were given, they should match explicitly */
118: for (i = 0; r->cmdargs[i]; i++) {
119: if (!cmdargs[i])
120: return 0;
121: if (strcmp(r->cmdargs[i], cmdargs[i]))
122: return 0;
123: }
124: if (cmdargs[i])
125: return 0;
126: }
127: }
1.1 tedu 128: return 1;
129: }
130:
131: static int
1.71 tedu 132: permit(uid_t uid, gid_t *groups, int ngroups, const struct rule **lastr,
1.15 zhuk 133: uid_t target, const char *cmd, const char **cmdargs)
1.1 tedu 134: {
135: int i;
136:
137: *lastr = NULL;
138: for (i = 0; i < nrules; i++) {
1.31 deraadt 139: if (match(uid, groups, ngroups, target, cmd,
140: cmdargs, rules[i]))
1.1 tedu 141: *lastr = rules[i];
142: }
143: if (!*lastr)
144: return 0;
145: return (*lastr)->action == PERMIT;
146: }
147:
148: static void
1.22 zhuk 149: parseconfig(const char *filename, int checkperms)
1.1 tedu 150: {
151: extern FILE *yyfp;
1.67 tedu 152: extern int yyparse(void);
1.6 nicm 153: struct stat sb;
1.1 tedu 154:
155: yyfp = fopen(filename, "r");
1.36 espie 156: if (!yyfp)
157: err(1, checkperms ? "doas is not enabled, %s" :
158: "could not open config file %s", filename);
1.6 nicm 159:
1.22 zhuk 160: if (checkperms) {
161: if (fstat(fileno(yyfp), &sb) != 0)
162: err(1, "fstat(\"%s\")", filename);
163: if ((sb.st_mode & (S_IWGRP|S_IWOTH)) != 0)
164: errx(1, "%s is writable by group or other", filename);
165: if (sb.st_uid != 0)
166: errx(1, "%s is not owned by root", filename);
167: }
1.6 nicm 168:
1.68 tb 169: yyparse();
1.1 tedu 170: fclose(yyfp);
1.21 zhuk 171: if (parse_errors)
172: exit(1);
1.1 tedu 173: }
174:
175: static void __dead
1.22 zhuk 176: checkconfig(const char *confpath, int argc, char **argv,
1.24 tedu 177: uid_t uid, gid_t *groups, int ngroups, uid_t target)
178: {
1.71 tedu 179: const struct rule *rule;
1.22 zhuk 180:
181: setresuid(uid, uid, uid);
182: parseconfig(confpath, 0);
183: if (!argc)
184: exit(0);
185:
186: if (permit(uid, groups, ngroups, &rule, target, argv[0],
187: (const char **)argv + 1)) {
188: printf("permit%s\n", (rule->options & NOPASS) ? " nopass" : "");
1.24 tedu 189: exit(0);
1.22 zhuk 190: } else {
191: printf("deny\n");
1.24 tedu 192: exit(1);
1.22 zhuk 193: }
194: }
195:
1.61 tedu 196: static void
1.63 tedu 197: authuser(char *myname, char *login_style, int persist)
1.61 tedu 198: {
199: char *challenge = NULL, *response, rbuf[1024], cbuf[128];
200: auth_session_t *as;
1.63 tedu 201: int fd = -1;
202:
203: if (persist)
204: fd = open("/dev/tty", O_RDWR);
205: if (fd != -1) {
206: if (ioctl(fd, TIOCCHKVERAUTH) == 0)
207: goto good;
208: }
1.61 tedu 209:
210: if (!(as = auth_userchallenge(myname, login_style, "auth-doas",
211: &challenge)))
212: errx(1, "Authorization failed");
213: if (!challenge) {
214: char host[HOST_NAME_MAX + 1];
215: if (gethostname(host, sizeof(host)))
216: snprintf(host, sizeof(host), "?");
217: snprintf(cbuf, sizeof(cbuf),
218: "\rdoas (%.32s@%.32s) password: ", myname, host);
219: challenge = cbuf;
220: }
221: response = readpassphrase(challenge, rbuf, sizeof(rbuf),
222: RPP_REQUIRE_TTY);
223: if (response == NULL && errno == ENOTTY) {
224: syslog(LOG_AUTHPRIV | LOG_NOTICE,
225: "tty required for %s", myname);
226: errx(1, "a tty is required");
227: }
228: if (!auth_userresponse(as, response, 0)) {
1.74 tedu 229: explicit_bzero(rbuf, sizeof(rbuf));
1.61 tedu 230: syslog(LOG_AUTHPRIV | LOG_NOTICE,
231: "failed auth for %s", myname);
1.72 tedu 232: errx(1, "Authorization failed");
1.61 tedu 233: }
234: explicit_bzero(rbuf, sizeof(rbuf));
1.63 tedu 235: good:
236: if (fd != -1) {
1.64 tedu 237: int secs = 5 * 60;
1.63 tedu 238: ioctl(fd, TIOCSETVERAUTH, &secs);
239: close(fd);
240: }
1.61 tedu 241: }
242:
1.1 tedu 243: int
1.73 deraadt 244: unveilcommands(const char *ipath, const char *cmd)
245: {
246: char *path = NULL, *p;
247: int unveils = 0;
248:
249: if (strchr(cmd, '/') != NULL) {
250: if (unveil(cmd, "x") != -1)
251: unveils++;
252: goto done;
253: }
254:
255: if (!ipath) {
256: errno = ENOENT;
257: goto done;
258: }
259: path = strdup(ipath);
260: if (!path) {
261: errno = ENOENT;
262: goto done;
263: }
264: for (p = path; p && *p; ) {
265: char buf[PATH_MAX];
266: char *cp = strsep(&p, ":");
267:
268: if (cp) {
269: int r = snprintf(buf, sizeof buf, "%s/%s", cp, cmd);
270: if (r != -1 && r < sizeof buf) {
271: if (unveil(buf, "x") != -1)
272: unveils++;
273: }
274: }
275: }
276: done:
277: free(path);
278: return (unveils);
279: }
280:
281: int
1.57 martijn 282: main(int argc, char **argv)
1.1 tedu 283: {
1.9 tedu 284: const char *safepath = "/bin:/sbin:/usr/bin:/usr/sbin:"
285: "/usr/local/bin:/usr/local/sbin";
1.22 zhuk 286: const char *confpath = NULL;
1.9 tedu 287: char *shargv[] = { NULL, NULL };
288: char *sh;
289: const char *cmd;
1.7 doug 290: char cmdline[LINE_MAX];
1.75 tedu 291: char mypwbuf[_PW_BUF_LEN], targpwbuf[_PW_BUF_LEN];
292: struct passwd mypwstore, targpwstore;
293: struct passwd *mypw, *targpw;
1.71 tedu 294: const struct rule *rule;
1.9 tedu 295: uid_t uid;
296: uid_t target = 0;
1.1 tedu 297: gid_t groups[NGROUPS_MAX + 1];
298: int ngroups;
1.75 tedu 299: int i, ch, rv;
1.8 nicm 300: int sflag = 0;
1.26 espie 301: int nflag = 0;
1.38 doug 302: char cwdpath[PATH_MAX];
303: const char *cwd;
1.47 sthen 304: char *login_style = NULL;
1.57 martijn 305: char **envp;
1.52 tedu 306:
307: setprogname("doas");
1.42 tedu 308:
309: closefrom(STDERR_FILENO + 1);
1.1 tedu 310:
1.26 espie 311: uid = getuid();
1.34 tedu 312:
1.63 tedu 313: while ((ch = getopt(argc, argv, "a:C:Lnsu:")) != -1) {
1.1 tedu 314: switch (ch) {
1.47 sthen 315: case 'a':
316: login_style = optarg;
317: break;
1.16 tedu 318: case 'C':
1.22 zhuk 319: confpath = optarg;
320: break;
1.63 tedu 321: case 'L':
322: i = open("/dev/tty", O_RDWR);
323: if (i != -1)
324: ioctl(i, TIOCCLRVERAUTH);
1.70 tedu 325: exit(i == -1);
1.1 tedu 326: case 'u':
327: if (parseuid(optarg, &target) != 0)
328: errx(1, "unknown user");
329: break;
1.26 espie 330: case 'n':
331: nflag = 1;
332: break;
1.8 nicm 333: case 's':
334: sflag = 1;
335: break;
1.1 tedu 336: default:
337: usage();
338: break;
339: }
340: }
341: argv += optind;
342: argc -= optind;
343:
1.22 zhuk 344: if (confpath) {
345: if (sflag)
346: usage();
347: } else if ((!sflag && !argc) || (sflag && argc))
1.1 tedu 348: usage();
1.16 tedu 349:
1.75 tedu 350: rv = getpwuid_r(uid, &mypwstore, mypwbuf, sizeof(mypwbuf), &mypw);
1.76 tedu 351: if (rv != 0)
1.75 tedu 352: err(1, "getpwuid_r failed");
1.76 tedu 353: if (mypw == NULL)
354: errx(1, "no passwd entry for self");
1.1 tedu 355: ngroups = getgroups(NGROUPS_MAX, groups);
356: if (ngroups == -1)
357: err(1, "can't get groups");
358: groups[ngroups++] = getgid();
1.8 nicm 359:
360: if (sflag) {
361: sh = getenv("SHELL");
1.60 zhuk 362: if (sh == NULL || *sh == '\0') {
1.76 tedu 363: shargv[0] = mypw->pw_shell;
1.60 zhuk 364: } else
1.8 nicm 365: shargv[0] = sh;
366: argv = shargv;
367: argc = 1;
368: }
1.22 zhuk 369:
1.24 tedu 370: if (confpath) {
371: checkconfig(confpath, argc, argv, uid, groups, ngroups,
372: target);
373: exit(1); /* fail safe */
374: }
1.69 tedu 375:
376: if (geteuid())
377: errx(1, "not installed setuid");
1.24 tedu 378:
1.22 zhuk 379: parseconfig("/etc/doas.conf", 1);
1.8 nicm 380:
1.23 zhuk 381: /* cmdline is used only for logging, no need to abort on truncate */
1.58 tedu 382: (void)strlcpy(cmdline, argv[0], sizeof(cmdline));
1.8 nicm 383: for (i = 1; i < argc; i++) {
384: if (strlcat(cmdline, " ", sizeof(cmdline)) >= sizeof(cmdline))
1.23 zhuk 385: break;
1.8 nicm 386: if (strlcat(cmdline, argv[i], sizeof(cmdline)) >= sizeof(cmdline))
1.23 zhuk 387: break;
1.8 nicm 388: }
1.1 tedu 389:
1.23 zhuk 390: cmd = argv[0];
1.15 zhuk 391: if (!permit(uid, groups, ngroups, &rule, target, cmd,
1.58 tedu 392: (const char **)argv + 1)) {
1.4 deraadt 393: syslog(LOG_AUTHPRIV | LOG_NOTICE,
1.76 tedu 394: "failed command for %s: %s", mypw->pw_name, cmdline);
1.41 tedu 395: errc(1, EPERM, NULL);
1.1 tedu 396: }
397:
398: if (!(rule->options & NOPASS)) {
1.26 espie 399: if (nflag)
400: errx(1, "Authorization required");
1.46 tedu 401:
1.76 tedu 402: authuser(mypw->pw_name, login_style, rule->options & PERSIST);
1.1 tedu 403: }
1.43 deraadt 404:
1.73 deraadt 405: if (unveil(_PATH_LOGIN_CONF, "r") == -1)
406: err(1, "unveil");
407: if (rule->cmd) {
408: if (setenv("PATH", safepath, 1) == -1)
409: err(1, "failed to set PATH '%s'", safepath);
410: }
411: if (unveilcommands(getenv("PATH"), cmd) == 0)
412: goto fail;
413:
1.43 deraadt 414: if (pledge("stdio rpath getpw exec id", NULL) == -1)
415: err(1, "pledge");
416:
1.75 tedu 417: rv = getpwuid_r(target, &targpwstore, targpwbuf, sizeof(targpwbuf), &targpw);
1.76 tedu 418: if (rv != 0)
419: err(1, "getpwuid_r failed");
420: if (targpw == NULL)
1.1 tedu 421: errx(1, "no passwd entry for target");
1.43 deraadt 422:
1.75 tedu 423: if (setusercontext(NULL, targpw, target, LOGIN_SETGROUP |
1.77 ! tedu 424: LOGIN_SETPATH |
1.1 tedu 425: LOGIN_SETPRIORITY | LOGIN_SETRESOURCES | LOGIN_SETUMASK |
426: LOGIN_SETUSER) != 0)
427: errx(1, "failed to set user context for target");
428:
1.43 deraadt 429: if (pledge("stdio rpath exec", NULL) == -1)
430: err(1, "pledge");
431:
1.38 doug 432: if (getcwd(cwdpath, sizeof(cwdpath)) == NULL)
433: cwd = "(failed)";
434: else
435: cwd = cwdpath;
1.43 deraadt 436:
437: if (pledge("stdio exec", NULL) == -1)
438: err(1, "pledge");
1.38 doug 439:
440: syslog(LOG_AUTHPRIV | LOG_INFO, "%s ran command %s as %s from %s",
1.76 tedu 441: mypw->pw_name, cmdline, targpw->pw_name, cwd);
1.44 tedu 442:
1.77 ! tedu 443: envp = prepenv(rule, mypw, targpw);
1.38 doug 444:
1.77 ! tedu 445: if (rule->cmd) {
! 446: /* do this again after setusercontext reset it */
! 447: if (setenv("PATH", safepath, 1) == -1)
! 448: err(1, "failed to set PATH '%s'", safepath);
! 449: }
1.1 tedu 450: execvpe(cmd, argv, envp);
1.73 deraadt 451: fail:
1.10 tedu 452: if (errno == ENOENT)
453: errx(1, "%s: command not found", cmd);
1.1 tedu 454: err(1, "%s", cmd);
455: }
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