File: [local] / src / usr.bin / doas / doas.c (download)
Revision 1.64, Sat Sep 3 11:03:18 2016 UTC (7 years, 9 months ago) by tedu
Branch: MAIN
Changes since 1.63: +2 -2 lines
the sudo timeout was 5 minutes i believe, so we'll match that.
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/* $OpenBSD: doas.c,v 1.64 2016/09/03 11:03:18 tedu Exp $ */
/*
* Copyright (c) 2015 Ted Unangst <tedu@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <limits.h>
#include <login_cap.h>
#include <bsd_auth.h>
#include <readpassphrase.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <err.h>
#include <unistd.h>
#include <pwd.h>
#include <grp.h>
#include <syslog.h>
#include <errno.h>
#include <fcntl.h>
#include "doas.h"
static void __dead
usage(void)
{
fprintf(stderr, "usage: doas [-Lns] [-a style] [-C config] [-u user]"
" command [args]\n");
exit(1);
}
size_t
arraylen(const char **arr)
{
size_t cnt = 0;
while (*arr) {
cnt++;
arr++;
}
return cnt;
}
static int
parseuid(const char *s, uid_t *uid)
{
struct passwd *pw;
const char *errstr;
if ((pw = getpwnam(s)) != NULL) {
*uid = pw->pw_uid;
return 0;
}
*uid = strtonum(s, 0, UID_MAX, &errstr);
if (errstr)
return -1;
return 0;
}
static int
uidcheck(const char *s, uid_t desired)
{
uid_t uid;
if (parseuid(s, &uid) != 0)
return -1;
if (uid != desired)
return -1;
return 0;
}
static int
parsegid(const char *s, gid_t *gid)
{
struct group *gr;
const char *errstr;
if ((gr = getgrnam(s)) != NULL) {
*gid = gr->gr_gid;
return 0;
}
*gid = strtonum(s, 0, GID_MAX, &errstr);
if (errstr)
return -1;
return 0;
}
static int
match(uid_t uid, gid_t *groups, int ngroups, uid_t target, const char *cmd,
const char **cmdargs, struct rule *r)
{
int i;
if (r->ident[0] == ':') {
gid_t rgid;
if (parsegid(r->ident + 1, &rgid) == -1)
return 0;
for (i = 0; i < ngroups; i++) {
if (rgid == groups[i])
break;
}
if (i == ngroups)
return 0;
} else {
if (uidcheck(r->ident, uid) != 0)
return 0;
}
if (r->target && uidcheck(r->target, target) != 0)
return 0;
if (r->cmd) {
if (strcmp(r->cmd, cmd))
return 0;
if (r->cmdargs) {
/* if arguments were given, they should match explicitly */
for (i = 0; r->cmdargs[i]; i++) {
if (!cmdargs[i])
return 0;
if (strcmp(r->cmdargs[i], cmdargs[i]))
return 0;
}
if (cmdargs[i])
return 0;
}
}
return 1;
}
static int
permit(uid_t uid, gid_t *groups, int ngroups, struct rule **lastr,
uid_t target, const char *cmd, const char **cmdargs)
{
int i;
*lastr = NULL;
for (i = 0; i < nrules; i++) {
if (match(uid, groups, ngroups, target, cmd,
cmdargs, rules[i]))
*lastr = rules[i];
}
if (!*lastr)
return 0;
return (*lastr)->action == PERMIT;
}
static void
parseconfig(const char *filename, int checkperms)
{
extern FILE *yyfp;
extern int yyparse(void);
struct stat sb;
yyfp = fopen(filename, "r");
if (!yyfp)
err(1, checkperms ? "doas is not enabled, %s" :
"could not open config file %s", filename);
if (checkperms) {
if (fstat(fileno(yyfp), &sb) != 0)
err(1, "fstat(\"%s\")", filename);
if ((sb.st_mode & (S_IWGRP|S_IWOTH)) != 0)
errx(1, "%s is writable by group or other", filename);
if (sb.st_uid != 0)
errx(1, "%s is not owned by root", filename);
}
yyparse();
fclose(yyfp);
if (parse_errors)
exit(1);
}
static void __dead
checkconfig(const char *confpath, int argc, char **argv,
uid_t uid, gid_t *groups, int ngroups, uid_t target)
{
struct rule *rule;
setresuid(uid, uid, uid);
parseconfig(confpath, 0);
if (!argc)
exit(0);
if (permit(uid, groups, ngroups, &rule, target, argv[0],
(const char **)argv + 1)) {
printf("permit%s\n", (rule->options & NOPASS) ? " nopass" : "");
exit(0);
} else {
printf("deny\n");
exit(1);
}
}
static void
authuser(char *myname, char *login_style, int persist)
{
char *challenge = NULL, *response, rbuf[1024], cbuf[128];
auth_session_t *as;
int fd = -1;
if (persist)
fd = open("/dev/tty", O_RDWR);
if (fd != -1) {
if (ioctl(fd, TIOCCHKVERAUTH) == 0)
goto good;
}
if (!(as = auth_userchallenge(myname, login_style, "auth-doas",
&challenge)))
errx(1, "Authorization failed");
if (!challenge) {
char host[HOST_NAME_MAX + 1];
if (gethostname(host, sizeof(host)))
snprintf(host, sizeof(host), "?");
snprintf(cbuf, sizeof(cbuf),
"\rdoas (%.32s@%.32s) password: ", myname, host);
challenge = cbuf;
}
response = readpassphrase(challenge, rbuf, sizeof(rbuf),
RPP_REQUIRE_TTY);
if (response == NULL && errno == ENOTTY) {
syslog(LOG_AUTHPRIV | LOG_NOTICE,
"tty required for %s", myname);
errx(1, "a tty is required");
}
if (!auth_userresponse(as, response, 0)) {
syslog(LOG_AUTHPRIV | LOG_NOTICE,
"failed auth for %s", myname);
errc(1, EPERM, NULL);
}
explicit_bzero(rbuf, sizeof(rbuf));
good:
if (fd != -1) {
int secs = 5 * 60;
ioctl(fd, TIOCSETVERAUTH, &secs);
close(fd);
}
}
int
main(int argc, char **argv)
{
const char *safepath = "/bin:/sbin:/usr/bin:/usr/sbin:"
"/usr/local/bin:/usr/local/sbin";
const char *confpath = NULL;
char *shargv[] = { NULL, NULL };
char *sh;
const char *cmd;
char cmdline[LINE_MAX];
char myname[_PW_NAME_LEN + 1];
struct passwd *pw;
struct rule *rule;
uid_t uid;
uid_t target = 0;
gid_t groups[NGROUPS_MAX + 1];
int ngroups;
int i, ch;
int sflag = 0;
int nflag = 0;
char cwdpath[PATH_MAX];
const char *cwd;
char *login_style = NULL;
char **envp;
setprogname("doas");
closefrom(STDERR_FILENO + 1);
uid = getuid();
while ((ch = getopt(argc, argv, "a:C:Lnsu:")) != -1) {
switch (ch) {
case 'a':
login_style = optarg;
break;
case 'C':
confpath = optarg;
break;
case 'L':
i = open("/dev/tty", O_RDWR);
if (i != -1)
ioctl(i, TIOCCLRVERAUTH);
exit(i != -1);
case 'u':
if (parseuid(optarg, &target) != 0)
errx(1, "unknown user");
break;
case 'n':
nflag = 1;
break;
case 's':
sflag = 1;
break;
default:
usage();
break;
}
}
argv += optind;
argc -= optind;
if (confpath) {
if (sflag)
usage();
} else if ((!sflag && !argc) || (sflag && argc))
usage();
pw = getpwuid(uid);
if (!pw)
err(1, "getpwuid failed");
if (strlcpy(myname, pw->pw_name, sizeof(myname)) >= sizeof(myname))
errx(1, "pw_name too long");
ngroups = getgroups(NGROUPS_MAX, groups);
if (ngroups == -1)
err(1, "can't get groups");
groups[ngroups++] = getgid();
if (sflag) {
sh = getenv("SHELL");
if (sh == NULL || *sh == '\0') {
shargv[0] = strdup(pw->pw_shell);
if (shargv[0] == NULL)
err(1, NULL);
} else
shargv[0] = sh;
argv = shargv;
argc = 1;
}
if (confpath) {
checkconfig(confpath, argc, argv, uid, groups, ngroups,
target);
exit(1); /* fail safe */
}
parseconfig("/etc/doas.conf", 1);
/* cmdline is used only for logging, no need to abort on truncate */
(void)strlcpy(cmdline, argv[0], sizeof(cmdline));
for (i = 1; i < argc; i++) {
if (strlcat(cmdline, " ", sizeof(cmdline)) >= sizeof(cmdline))
break;
if (strlcat(cmdline, argv[i], sizeof(cmdline)) >= sizeof(cmdline))
break;
}
cmd = argv[0];
if (!permit(uid, groups, ngroups, &rule, target, cmd,
(const char **)argv + 1)) {
syslog(LOG_AUTHPRIV | LOG_NOTICE,
"failed command for %s: %s", myname, cmdline);
errc(1, EPERM, NULL);
}
if (!(rule->options & NOPASS)) {
if (nflag)
errx(1, "Authorization required");
authuser(myname, login_style, rule->options & PERSIST);
}
if (pledge("stdio rpath getpw exec id", NULL) == -1)
err(1, "pledge");
pw = getpwuid(target);
if (!pw)
errx(1, "no passwd entry for target");
if (setusercontext(NULL, pw, target, LOGIN_SETGROUP |
LOGIN_SETPRIORITY | LOGIN_SETRESOURCES | LOGIN_SETUMASK |
LOGIN_SETUSER) != 0)
errx(1, "failed to set user context for target");
if (pledge("stdio rpath exec", NULL) == -1)
err(1, "pledge");
if (getcwd(cwdpath, sizeof(cwdpath)) == NULL)
cwd = "(failed)";
else
cwd = cwdpath;
if (pledge("stdio exec", NULL) == -1)
err(1, "pledge");
syslog(LOG_AUTHPRIV | LOG_INFO, "%s ran command %s as %s from %s",
myname, cmdline, pw->pw_name, cwd);
envp = prepenv(rule);
if (rule->cmd) {
if (setenv("PATH", safepath, 1) == -1)
err(1, "failed to set PATH '%s'", safepath);
}
execvpe(cmd, argv, envp);
if (errno == ENOENT)
errx(1, "%s: command not found", cmd);
err(1, "%s", cmd);
}