Annotation of src/usr.bin/doas/doas.c, Revision 1.65
1.65 ! deraadt 1: /* $OpenBSD: doas.c,v 1.64 2016/09/03 11:03:18 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: size_t
48: arraylen(const char **arr)
49: {
50: size_t cnt = 0;
1.9 tedu 51:
1.1 tedu 52: while (*arr) {
53: cnt++;
54: arr++;
55: }
56: return cnt;
57: }
58:
59: static int
60: parseuid(const char *s, uid_t *uid)
61: {
62: struct passwd *pw;
63: const char *errstr;
64:
65: if ((pw = getpwnam(s)) != NULL) {
66: *uid = pw->pw_uid;
67: return 0;
68: }
69: *uid = strtonum(s, 0, UID_MAX, &errstr);
70: if (errstr)
71: return -1;
72: return 0;
73: }
74:
75: static int
76: uidcheck(const char *s, uid_t desired)
77: {
78: uid_t uid;
79:
80: if (parseuid(s, &uid) != 0)
81: return -1;
82: if (uid != desired)
83: return -1;
84: return 0;
85: }
86:
1.33 tedu 87: static int
88: parsegid(const char *s, gid_t *gid)
1.1 tedu 89: {
90: struct group *gr;
91: const char *errstr;
92:
1.33 tedu 93: if ((gr = getgrnam(s)) != NULL) {
94: *gid = gr->gr_gid;
95: return 0;
96: }
97: *gid = strtonum(s, 0, GID_MAX, &errstr);
1.1 tedu 98: if (errstr)
99: return -1;
1.33 tedu 100: return 0;
1.1 tedu 101: }
102:
103: static int
104: match(uid_t uid, gid_t *groups, int ngroups, uid_t target, const char *cmd,
1.15 zhuk 105: const char **cmdargs, struct rule *r)
1.1 tedu 106: {
107: int i;
108:
109: if (r->ident[0] == ':') {
1.33 tedu 110: gid_t rgid;
111: if (parsegid(r->ident + 1, &rgid) == -1)
1.1 tedu 112: return 0;
113: for (i = 0; i < ngroups; i++) {
114: if (rgid == groups[i])
115: break;
116: }
117: if (i == ngroups)
118: return 0;
119: } else {
120: if (uidcheck(r->ident, uid) != 0)
121: return 0;
122: }
123: if (r->target && uidcheck(r->target, target) != 0)
124: return 0;
1.15 zhuk 125: if (r->cmd) {
126: if (strcmp(r->cmd, cmd))
127: return 0;
128: if (r->cmdargs) {
129: /* if arguments were given, they should match explicitly */
130: for (i = 0; r->cmdargs[i]; i++) {
131: if (!cmdargs[i])
132: return 0;
133: if (strcmp(r->cmdargs[i], cmdargs[i]))
134: return 0;
135: }
136: if (cmdargs[i])
137: return 0;
138: }
139: }
1.1 tedu 140: return 1;
141: }
142:
143: static int
144: permit(uid_t uid, gid_t *groups, int ngroups, struct rule **lastr,
1.15 zhuk 145: uid_t target, const char *cmd, const char **cmdargs)
1.1 tedu 146: {
147: int i;
148:
149: *lastr = NULL;
150: for (i = 0; i < nrules; i++) {
1.31 deraadt 151: if (match(uid, groups, ngroups, target, cmd,
152: cmdargs, rules[i]))
1.1 tedu 153: *lastr = rules[i];
154: }
155: if (!*lastr)
156: return 0;
157: return (*lastr)->action == PERMIT;
158: }
159:
160: static void
1.22 zhuk 161: parseconfig(const char *filename, int checkperms)
1.1 tedu 162: {
163: extern FILE *yyfp;
1.6 nicm 164: struct stat sb;
1.1 tedu 165:
166: yyfp = fopen(filename, "r");
1.36 espie 167: if (!yyfp)
168: err(1, checkperms ? "doas is not enabled, %s" :
169: "could not open config file %s", filename);
1.6 nicm 170:
1.22 zhuk 171: if (checkperms) {
172: if (fstat(fileno(yyfp), &sb) != 0)
173: err(1, "fstat(\"%s\")", filename);
174: if ((sb.st_mode & (S_IWGRP|S_IWOTH)) != 0)
175: errx(1, "%s is writable by group or other", filename);
176: if (sb.st_uid != 0)
177: errx(1, "%s is not owned by root", filename);
178: }
1.6 nicm 179:
1.1 tedu 180: yyparse();
181: fclose(yyfp);
1.21 zhuk 182: if (parse_errors)
183: exit(1);
1.1 tedu 184: }
185:
186: static void __dead
1.22 zhuk 187: checkconfig(const char *confpath, int argc, char **argv,
1.24 tedu 188: uid_t uid, gid_t *groups, int ngroups, uid_t target)
189: {
1.22 zhuk 190: struct rule *rule;
191:
192: setresuid(uid, uid, uid);
193: parseconfig(confpath, 0);
194: if (!argc)
195: exit(0);
196:
197: if (permit(uid, groups, ngroups, &rule, target, argv[0],
198: (const char **)argv + 1)) {
199: printf("permit%s\n", (rule->options & NOPASS) ? " nopass" : "");
1.24 tedu 200: exit(0);
1.22 zhuk 201: } else {
202: printf("deny\n");
1.24 tedu 203: exit(1);
1.22 zhuk 204: }
205: }
206:
1.61 tedu 207: static void
1.63 tedu 208: authuser(char *myname, char *login_style, int persist)
1.61 tedu 209: {
210: char *challenge = NULL, *response, rbuf[1024], cbuf[128];
211: auth_session_t *as;
1.63 tedu 212: int fd = -1;
213:
214: if (persist)
215: fd = open("/dev/tty", O_RDWR);
216: if (fd != -1) {
217: if (ioctl(fd, TIOCCHKVERAUTH) == 0)
218: goto good;
219: }
1.61 tedu 220:
221: if (!(as = auth_userchallenge(myname, login_style, "auth-doas",
222: &challenge)))
223: errx(1, "Authorization failed");
224: if (!challenge) {
225: char host[HOST_NAME_MAX + 1];
226: if (gethostname(host, sizeof(host)))
227: snprintf(host, sizeof(host), "?");
228: snprintf(cbuf, sizeof(cbuf),
229: "\rdoas (%.32s@%.32s) password: ", myname, host);
230: challenge = cbuf;
231: }
232: response = readpassphrase(challenge, rbuf, sizeof(rbuf),
233: RPP_REQUIRE_TTY);
234: if (response == NULL && errno == ENOTTY) {
235: syslog(LOG_AUTHPRIV | LOG_NOTICE,
236: "tty required for %s", myname);
237: errx(1, "a tty is required");
238: }
239: if (!auth_userresponse(as, response, 0)) {
240: syslog(LOG_AUTHPRIV | LOG_NOTICE,
241: "failed auth for %s", myname);
242: errc(1, EPERM, NULL);
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
1.57 martijn 254: main(int argc, char **argv)
1.1 tedu 255: {
1.9 tedu 256: const char *safepath = "/bin:/sbin:/usr/bin:/usr/sbin:"
257: "/usr/local/bin:/usr/local/sbin";
1.22 zhuk 258: const char *confpath = NULL;
1.9 tedu 259: char *shargv[] = { NULL, NULL };
260: char *sh;
261: const char *cmd;
1.7 doug 262: char cmdline[LINE_MAX];
263: char myname[_PW_NAME_LEN + 1];
1.9 tedu 264: struct passwd *pw;
265: struct rule *rule;
266: uid_t uid;
267: uid_t target = 0;
1.1 tedu 268: gid_t groups[NGROUPS_MAX + 1];
269: int ngroups;
270: int i, ch;
1.8 nicm 271: int sflag = 0;
1.26 espie 272: int nflag = 0;
1.38 doug 273: char cwdpath[PATH_MAX];
274: const char *cwd;
1.47 sthen 275: char *login_style = NULL;
1.57 martijn 276: char **envp;
1.52 tedu 277:
278: setprogname("doas");
1.42 tedu 279:
280: closefrom(STDERR_FILENO + 1);
1.1 tedu 281:
1.26 espie 282: uid = getuid();
1.34 tedu 283:
1.63 tedu 284: while ((ch = getopt(argc, argv, "a:C:Lnsu:")) != -1) {
1.1 tedu 285: switch (ch) {
1.47 sthen 286: case 'a':
287: login_style = optarg;
288: break;
1.16 tedu 289: case 'C':
1.22 zhuk 290: confpath = optarg;
291: break;
1.63 tedu 292: case 'L':
293: i = open("/dev/tty", O_RDWR);
294: if (i != -1)
295: ioctl(i, TIOCCLRVERAUTH);
296: exit(i != -1);
1.1 tedu 297: case 'u':
298: if (parseuid(optarg, &target) != 0)
299: errx(1, "unknown user");
300: break;
1.26 espie 301: case 'n':
302: nflag = 1;
303: break;
1.8 nicm 304: case 's':
305: sflag = 1;
306: break;
1.1 tedu 307: default:
308: usage();
309: break;
310: }
311: }
312: argv += optind;
313: argc -= optind;
314:
1.22 zhuk 315: if (confpath) {
316: if (sflag)
317: usage();
318: } else if ((!sflag && !argc) || (sflag && argc))
1.1 tedu 319: usage();
1.16 tedu 320:
1.1 tedu 321: pw = getpwuid(uid);
322: if (!pw)
323: err(1, "getpwuid failed");
1.7 doug 324: if (strlcpy(myname, pw->pw_name, sizeof(myname)) >= sizeof(myname))
325: errx(1, "pw_name too long");
1.1 tedu 326: ngroups = getgroups(NGROUPS_MAX, groups);
327: if (ngroups == -1)
328: err(1, "can't get groups");
329: groups[ngroups++] = getgid();
1.8 nicm 330:
331: if (sflag) {
332: sh = getenv("SHELL");
1.60 zhuk 333: if (sh == NULL || *sh == '\0') {
334: shargv[0] = strdup(pw->pw_shell);
335: if (shargv[0] == NULL)
336: err(1, NULL);
337: } else
1.8 nicm 338: shargv[0] = sh;
339: argv = shargv;
340: argc = 1;
341: }
1.22 zhuk 342:
1.24 tedu 343: if (confpath) {
344: checkconfig(confpath, argc, argv, uid, groups, ngroups,
345: target);
346: exit(1); /* fail safe */
347: }
348:
1.22 zhuk 349: parseconfig("/etc/doas.conf", 1);
1.8 nicm 350:
1.23 zhuk 351: /* cmdline is used only for logging, no need to abort on truncate */
1.58 tedu 352: (void)strlcpy(cmdline, argv[0], sizeof(cmdline));
1.8 nicm 353: for (i = 1; i < argc; i++) {
354: if (strlcat(cmdline, " ", sizeof(cmdline)) >= sizeof(cmdline))
1.23 zhuk 355: break;
1.8 nicm 356: if (strlcat(cmdline, argv[i], sizeof(cmdline)) >= sizeof(cmdline))
1.23 zhuk 357: break;
1.8 nicm 358: }
1.1 tedu 359:
1.23 zhuk 360: cmd = argv[0];
1.15 zhuk 361: if (!permit(uid, groups, ngroups, &rule, target, cmd,
1.58 tedu 362: (const char **)argv + 1)) {
1.4 deraadt 363: syslog(LOG_AUTHPRIV | LOG_NOTICE,
364: "failed command for %s: %s", myname, cmdline);
1.41 tedu 365: errc(1, EPERM, NULL);
1.1 tedu 366: }
367:
368: if (!(rule->options & NOPASS)) {
1.26 espie 369: if (nflag)
370: errx(1, "Authorization required");
1.46 tedu 371:
1.63 tedu 372: authuser(myname, login_style, rule->options & PERSIST);
1.1 tedu 373: }
1.43 deraadt 374:
375: if (pledge("stdio rpath getpw exec id", NULL) == -1)
376: err(1, "pledge");
377:
1.1 tedu 378: pw = getpwuid(target);
379: if (!pw)
380: errx(1, "no passwd entry for target");
1.43 deraadt 381:
1.1 tedu 382: if (setusercontext(NULL, pw, target, LOGIN_SETGROUP |
383: LOGIN_SETPRIORITY | LOGIN_SETRESOURCES | LOGIN_SETUMASK |
384: LOGIN_SETUSER) != 0)
385: errx(1, "failed to set user context for target");
386:
1.43 deraadt 387: if (pledge("stdio rpath exec", NULL) == -1)
388: err(1, "pledge");
389:
1.38 doug 390: if (getcwd(cwdpath, sizeof(cwdpath)) == NULL)
391: cwd = "(failed)";
392: else
393: cwd = cwdpath;
1.43 deraadt 394:
395: if (pledge("stdio exec", NULL) == -1)
396: err(1, "pledge");
1.38 doug 397:
398: syslog(LOG_AUTHPRIV | LOG_INFO, "%s ran command %s as %s from %s",
399: myname, cmdline, pw->pw_name, cwd);
1.44 tedu 400:
1.57 martijn 401: envp = prepenv(rule);
1.38 doug 402:
1.40 tedu 403: if (rule->cmd) {
404: if (setenv("PATH", safepath, 1) == -1)
405: err(1, "failed to set PATH '%s'", safepath);
406: }
1.1 tedu 407: execvpe(cmd, argv, envp);
1.10 tedu 408: if (errno == ENOENT)
409: errx(1, "%s: command not found", cmd);
1.1 tedu 410: err(1, "%s", cmd);
411: }
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