Annotation of src/usr.bin/doas/doas.c, Revision 1.67
1.67 ! tedu 1: /* $OpenBSD: doas.c,v 1.66 2016/10/05 17:36:53 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
132: permit(uid_t uid, gid_t *groups, int ngroups, 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:
1.1 tedu 169: fclose(yyfp);
1.21 zhuk 170: if (parse_errors)
171: exit(1);
1.1 tedu 172: }
173:
174: static void __dead
1.22 zhuk 175: checkconfig(const char *confpath, int argc, char **argv,
1.24 tedu 176: uid_t uid, gid_t *groups, int ngroups, uid_t target)
177: {
1.22 zhuk 178: struct rule *rule;
179:
180: setresuid(uid, uid, uid);
181: parseconfig(confpath, 0);
182: if (!argc)
183: exit(0);
184:
185: if (permit(uid, groups, ngroups, &rule, target, argv[0],
186: (const char **)argv + 1)) {
187: printf("permit%s\n", (rule->options & NOPASS) ? " nopass" : "");
1.24 tedu 188: exit(0);
1.22 zhuk 189: } else {
190: printf("deny\n");
1.24 tedu 191: exit(1);
1.22 zhuk 192: }
193: }
194:
1.61 tedu 195: static void
1.63 tedu 196: authuser(char *myname, char *login_style, int persist)
1.61 tedu 197: {
198: char *challenge = NULL, *response, rbuf[1024], cbuf[128];
199: auth_session_t *as;
1.63 tedu 200: int fd = -1;
201:
202: if (persist)
203: fd = open("/dev/tty", O_RDWR);
204: if (fd != -1) {
205: if (ioctl(fd, TIOCCHKVERAUTH) == 0)
206: goto good;
207: }
1.61 tedu 208:
209: if (!(as = auth_userchallenge(myname, login_style, "auth-doas",
210: &challenge)))
211: errx(1, "Authorization failed");
212: if (!challenge) {
213: char host[HOST_NAME_MAX + 1];
214: if (gethostname(host, sizeof(host)))
215: snprintf(host, sizeof(host), "?");
216: snprintf(cbuf, sizeof(cbuf),
217: "\rdoas (%.32s@%.32s) password: ", myname, host);
218: challenge = cbuf;
219: }
220: response = readpassphrase(challenge, rbuf, sizeof(rbuf),
221: RPP_REQUIRE_TTY);
222: if (response == NULL && errno == ENOTTY) {
223: syslog(LOG_AUTHPRIV | LOG_NOTICE,
224: "tty required for %s", myname);
225: errx(1, "a tty is required");
226: }
227: if (!auth_userresponse(as, response, 0)) {
228: syslog(LOG_AUTHPRIV | LOG_NOTICE,
229: "failed auth for %s", myname);
230: errc(1, EPERM, NULL);
231: }
232: explicit_bzero(rbuf, sizeof(rbuf));
1.63 tedu 233: good:
234: if (fd != -1) {
1.64 tedu 235: int secs = 5 * 60;
1.63 tedu 236: ioctl(fd, TIOCSETVERAUTH, &secs);
237: close(fd);
238: }
1.61 tedu 239: }
240:
1.1 tedu 241: int
1.57 martijn 242: main(int argc, char **argv)
1.1 tedu 243: {
1.9 tedu 244: const char *safepath = "/bin:/sbin:/usr/bin:/usr/sbin:"
245: "/usr/local/bin:/usr/local/sbin";
1.22 zhuk 246: const char *confpath = NULL;
1.9 tedu 247: char *shargv[] = { NULL, NULL };
248: char *sh;
249: const char *cmd;
1.7 doug 250: char cmdline[LINE_MAX];
251: char myname[_PW_NAME_LEN + 1];
1.9 tedu 252: struct passwd *pw;
253: struct rule *rule;
254: uid_t uid;
255: uid_t target = 0;
1.1 tedu 256: gid_t groups[NGROUPS_MAX + 1];
257: int ngroups;
258: int i, ch;
1.8 nicm 259: int sflag = 0;
1.26 espie 260: int nflag = 0;
1.38 doug 261: char cwdpath[PATH_MAX];
262: const char *cwd;
1.47 sthen 263: char *login_style = NULL;
1.57 martijn 264: char **envp;
1.52 tedu 265:
266: setprogname("doas");
1.42 tedu 267:
268: closefrom(STDERR_FILENO + 1);
1.1 tedu 269:
1.26 espie 270: uid = getuid();
1.34 tedu 271:
1.63 tedu 272: while ((ch = getopt(argc, argv, "a:C:Lnsu:")) != -1) {
1.1 tedu 273: switch (ch) {
1.47 sthen 274: case 'a':
275: login_style = optarg;
276: break;
1.16 tedu 277: case 'C':
1.22 zhuk 278: confpath = optarg;
279: break;
1.63 tedu 280: case 'L':
281: i = open("/dev/tty", O_RDWR);
282: if (i != -1)
283: ioctl(i, TIOCCLRVERAUTH);
284: exit(i != -1);
1.1 tedu 285: case 'u':
286: if (parseuid(optarg, &target) != 0)
287: errx(1, "unknown user");
288: break;
1.26 espie 289: case 'n':
290: nflag = 1;
291: break;
1.8 nicm 292: case 's':
293: sflag = 1;
294: break;
1.1 tedu 295: default:
296: usage();
297: break;
298: }
299: }
300: argv += optind;
301: argc -= optind;
302:
1.22 zhuk 303: if (confpath) {
304: if (sflag)
305: usage();
306: } else if ((!sflag && !argc) || (sflag && argc))
1.1 tedu 307: usage();
1.16 tedu 308:
1.1 tedu 309: pw = getpwuid(uid);
310: if (!pw)
311: err(1, "getpwuid failed");
1.7 doug 312: if (strlcpy(myname, pw->pw_name, sizeof(myname)) >= sizeof(myname))
313: errx(1, "pw_name too long");
1.1 tedu 314: ngroups = getgroups(NGROUPS_MAX, groups);
315: if (ngroups == -1)
316: err(1, "can't get groups");
317: groups[ngroups++] = getgid();
1.8 nicm 318:
319: if (sflag) {
320: sh = getenv("SHELL");
1.60 zhuk 321: if (sh == NULL || *sh == '\0') {
322: shargv[0] = strdup(pw->pw_shell);
323: if (shargv[0] == NULL)
324: err(1, NULL);
325: } else
1.8 nicm 326: shargv[0] = sh;
327: argv = shargv;
328: argc = 1;
329: }
1.22 zhuk 330:
1.24 tedu 331: if (confpath) {
332: checkconfig(confpath, argc, argv, uid, groups, ngroups,
333: target);
334: exit(1); /* fail safe */
335: }
336:
1.22 zhuk 337: parseconfig("/etc/doas.conf", 1);
1.8 nicm 338:
1.23 zhuk 339: /* cmdline is used only for logging, no need to abort on truncate */
1.58 tedu 340: (void)strlcpy(cmdline, argv[0], sizeof(cmdline));
1.8 nicm 341: for (i = 1; i < argc; i++) {
342: if (strlcat(cmdline, " ", sizeof(cmdline)) >= sizeof(cmdline))
1.23 zhuk 343: break;
1.8 nicm 344: if (strlcat(cmdline, argv[i], sizeof(cmdline)) >= sizeof(cmdline))
1.23 zhuk 345: break;
1.8 nicm 346: }
1.1 tedu 347:
1.23 zhuk 348: cmd = argv[0];
1.15 zhuk 349: if (!permit(uid, groups, ngroups, &rule, target, cmd,
1.58 tedu 350: (const char **)argv + 1)) {
1.4 deraadt 351: syslog(LOG_AUTHPRIV | LOG_NOTICE,
352: "failed command for %s: %s", myname, cmdline);
1.41 tedu 353: errc(1, EPERM, NULL);
1.1 tedu 354: }
355:
356: if (!(rule->options & NOPASS)) {
1.26 espie 357: if (nflag)
358: errx(1, "Authorization required");
1.46 tedu 359:
1.63 tedu 360: authuser(myname, login_style, rule->options & PERSIST);
1.1 tedu 361: }
1.43 deraadt 362:
363: if (pledge("stdio rpath getpw exec id", NULL) == -1)
364: err(1, "pledge");
365:
1.1 tedu 366: pw = getpwuid(target);
367: if (!pw)
368: errx(1, "no passwd entry for target");
1.43 deraadt 369:
1.1 tedu 370: if (setusercontext(NULL, pw, target, LOGIN_SETGROUP |
371: LOGIN_SETPRIORITY | LOGIN_SETRESOURCES | LOGIN_SETUMASK |
372: LOGIN_SETUSER) != 0)
373: errx(1, "failed to set user context for target");
374:
1.43 deraadt 375: if (pledge("stdio rpath exec", NULL) == -1)
376: err(1, "pledge");
377:
1.38 doug 378: if (getcwd(cwdpath, sizeof(cwdpath)) == NULL)
379: cwd = "(failed)";
380: else
381: cwd = cwdpath;
1.43 deraadt 382:
383: if (pledge("stdio exec", NULL) == -1)
384: err(1, "pledge");
1.38 doug 385:
386: syslog(LOG_AUTHPRIV | LOG_INFO, "%s ran command %s as %s from %s",
387: myname, cmdline, pw->pw_name, cwd);
1.44 tedu 388:
1.57 martijn 389: envp = prepenv(rule);
1.38 doug 390:
1.40 tedu 391: if (rule->cmd) {
392: if (setenv("PATH", safepath, 1) == -1)
393: err(1, "failed to set PATH '%s'", safepath);
394: }
1.1 tedu 395: execvpe(cmd, argv, envp);
1.10 tedu 396: if (errno == ENOENT)
397: errx(1, "%s: command not found", cmd);
1.1 tedu 398: err(1, "%s", cmd);
399: }
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