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/* $OpenBSD: doas.c,v 1.3 2017/01/21 08:18:53 krw 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 <limits.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>
static void __dead
usage(void)
{
fprintf(stderr, "usage: doas [-u user] command [args]\n");
exit(1);
}
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;
}
int
main(int argc, char **argv)
{
const char *cmd;
struct passwd *pw;
uid_t uid;
uid_t target = 0;
gid_t groups[1];
int ch;
setprogname("doas");
closefrom(STDERR_FILENO + 1);
uid = getuid();
if (uid != 0)
errc(1, EPERM, "root only");
while ((ch = getopt(argc, argv, "u:")) != -1) {
switch (ch) {
case 'u':
if (parseuid(optarg, &target) != 0)
errx(1, "unknown user");
break;
default:
usage();
break;
}
}
argv += optind;
argc -= optind;
if (!argc)
usage();
cmd = argv[0];
pw = getpwuid(target);
if (!pw)
errx(1, "no passwd entry for target");
groups[0] = pw->pw_gid;
if (setgroups(1, groups) ||
setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
err(1, "failed to change user");
execvp(cmd, argv);
if (errno == ENOENT)
errx(1, "%s: command not found", cmd);
err(1, "%s", cmd);
}
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