430 lines
9.2 KiB
C
430 lines
9.2 KiB
C
/* $OpenBSD: doas.c,v 1.52 2016/04/28 04:48:56 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 "config.h"
|
|
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
#include <sys/ioctl.h>
|
|
|
|
#include <limits.h>
|
|
#ifdef HAVE_LOGIN_CAP_H
|
|
#include <login_cap.h>
|
|
#endif
|
|
#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 "openbsd.h"
|
|
#include "doas.h"
|
|
|
|
static void __dead
|
|
usage(void)
|
|
{
|
|
fprintf(stderr, "usage: doas [-Lns] [-C config] [-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;
|
|
if (*uid == UID_MAX)
|
|
return -1;
|
|
return 0;
|
|
}
|
|
*uid = strtonum(s, 0, UID_MAX - 1, &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;
|
|
if (*gid == GID_MAX)
|
|
return -1;
|
|
return 0;
|
|
}
|
|
*gid = strtonum(s, 0, GID_MAX - 1, &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, const struct rule **lastr,
|
|
uid_t target, const char *cmd, const char **cmdargs)
|
|
{
|
|
size_t 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)
|
|
{
|
|
const struct rule *rule;
|
|
|
|
if (setresuid(uid, uid, uid) != 0)
|
|
err(1, "setresuid");
|
|
|
|
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);
|
|
}
|
|
}
|
|
|
|
int
|
|
mygetpwuid_r(uid_t uid, struct passwd *pwd, struct passwd **result)
|
|
{
|
|
int rv;
|
|
char *buf;
|
|
static long pwsz = 0;
|
|
size_t buflen;
|
|
|
|
*result = NULL;
|
|
|
|
if (pwsz == 0)
|
|
pwsz = sysconf(_SC_GETPW_R_SIZE_MAX);
|
|
|
|
buflen = pwsz > 0 ? pwsz : 1024;
|
|
|
|
buf = malloc(buflen);
|
|
if (buf == NULL)
|
|
return errno;
|
|
|
|
while ((rv = getpwuid_r(uid, pwd, buf, buflen, result)) == ERANGE) {
|
|
size_t newsz;
|
|
newsz = buflen * 2;
|
|
if (newsz < buflen)
|
|
return rv;
|
|
buflen = newsz;
|
|
buf = realloc(buf, buflen);
|
|
if (buf == NULL)
|
|
return errno;
|
|
}
|
|
|
|
return rv;
|
|
}
|
|
|
|
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 *p;
|
|
const char *cmd;
|
|
char cmdline[LINE_MAX];
|
|
struct passwd mypwstore, targpwstore;
|
|
struct passwd *mypw, *targpw;
|
|
const struct rule *rule;
|
|
uid_t uid;
|
|
uid_t target = 0;
|
|
gid_t groups[NGROUPS_MAX + 1];
|
|
int ngroups;
|
|
int i, ch, rv;
|
|
int sflag = 0;
|
|
int nflag = 0;
|
|
char cwdpath[PATH_MAX];
|
|
const char *cwd;
|
|
char **envp;
|
|
|
|
setprogname("doas");
|
|
|
|
closefrom(STDERR_FILENO + 1);
|
|
|
|
uid = getuid();
|
|
|
|
while ((ch = getopt(argc, argv, "+C:Lnsu:")) != -1) {
|
|
switch (ch) {
|
|
case 'C':
|
|
confpath = optarg;
|
|
break;
|
|
case 'L':
|
|
#if defined(USE_TIMESTAMP)
|
|
exit(timestamp_clear() == -1);
|
|
#else
|
|
exit(0);
|
|
#endif
|
|
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();
|
|
|
|
rv = mygetpwuid_r(uid, &mypwstore, &mypw);
|
|
if (rv != 0)
|
|
err(1, "getpwuid_r failed");
|
|
if (mypw == NULL)
|
|
errx(1, "no passwd entry for self");
|
|
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] = mypw->pw_shell;
|
|
} else
|
|
shargv[0] = sh;
|
|
argv = shargv;
|
|
argc = 1;
|
|
}
|
|
|
|
if (confpath) {
|
|
checkconfig(confpath, argc, argv, uid, groups, ngroups,
|
|
target);
|
|
exit(1); /* fail safe */
|
|
}
|
|
|
|
if (geteuid())
|
|
errx(1, "not installed setuid");
|
|
|
|
parseconfig(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,
|
|
"command not permitted for %s: %s", mypw->pw_name, cmdline);
|
|
errc(1, EPERM, NULL);
|
|
}
|
|
|
|
#if defined(USE_SHADOW)
|
|
if (!(rule->options & NOPASS)) {
|
|
if (nflag)
|
|
errx(1, "Authentication required");
|
|
|
|
shadowauth(mypw->pw_name, rule->options & PERSIST);
|
|
}
|
|
#elif !defined(USE_PAM)
|
|
/* no authentication provider, only allow NOPASS rules */
|
|
(void) nflag;
|
|
if (!(rule->options & NOPASS))
|
|
errx(1, "Authentication required");
|
|
#endif
|
|
|
|
if ((p = getenv("PATH")) != NULL)
|
|
formerpath = strdup(p);
|
|
if (formerpath == NULL)
|
|
formerpath = "";
|
|
|
|
if (rule->cmd) {
|
|
if (setenv("PATH", safepath, 1) == -1)
|
|
err(1, "failed to set PATH '%s'", safepath);
|
|
}
|
|
|
|
rv = mygetpwuid_r(target, &targpwstore, &targpw);
|
|
if (rv != 0)
|
|
err(1, "getpwuid_r failed");
|
|
if (targpw == NULL)
|
|
errx(1, "no passwd entry for target");
|
|
|
|
#if defined(USE_PAM)
|
|
pamauth(targpw->pw_name, mypw->pw_name, !nflag, rule->options & NOPASS,
|
|
rule->options & PERSIST);
|
|
#endif
|
|
|
|
#ifdef HAVE_LOGIN_CAP_H
|
|
if (setusercontext(NULL, targpw, target, LOGIN_SETGROUP |
|
|
LOGIN_SETPATH |
|
|
LOGIN_SETPRIORITY | LOGIN_SETRESOURCES | LOGIN_SETUMASK |
|
|
LOGIN_SETUSER) != 0)
|
|
errx(1, "failed to set user context for target");
|
|
#else
|
|
if (setresgid(targpw->pw_gid, targpw->pw_gid, targpw->pw_gid) != 0)
|
|
err(1, "setresgid");
|
|
if (initgroups(targpw->pw_name, targpw->pw_gid) != 0)
|
|
err(1, "initgroups");
|
|
if (setresuid(target, target, target) != 0)
|
|
err(1, "setresuid");
|
|
if (setenv("PATH", safepath, 1) == -1)
|
|
err(1, "failed to set PATH '%s'", safepath);
|
|
#endif
|
|
|
|
if (getcwd(cwdpath, sizeof(cwdpath)) == NULL)
|
|
cwd = "(failed)";
|
|
else
|
|
cwd = cwdpath;
|
|
|
|
if (!(rule->options & NOLOG)) {
|
|
syslog(LOG_AUTHPRIV | LOG_INFO,
|
|
"%s ran command %s as %s from %s",
|
|
mypw->pw_name, cmdline, targpw->pw_name, cwd);
|
|
}
|
|
|
|
envp = prepenv(rule, mypw, targpw);
|
|
|
|
/* setusercontext set path for the next process, so reset it for us */
|
|
if (rule->cmd) {
|
|
if (setenv("PATH", safepath, 1) == -1)
|
|
err(1, "failed to set PATH '%s'", safepath);
|
|
} else {
|
|
if (setenv("PATH", formerpath, 1) == -1)
|
|
err(1, "failed to set PATH '%s'", formerpath);
|
|
}
|
|
execvpe(cmd, argv, envp);
|
|
if (errno == ENOENT)
|
|
errx(1, "%s: command not found", cmd);
|
|
err(1, "%s", cmd);
|
|
}
|