freebsd-dev/usr.bin/newgrp/newgrp.c

311 lines
6.6 KiB
C

/*-
* Copyright (c) 2002 Tim J. Robbins.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* newgrp -- change to a new group
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <err.h>
#include <errno.h>
#include <grp.h>
#include <libgen.h>
#include <limits.h>
#include <login_cap.h>
#include <paths.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
static void addgroup(const char *grpname);
static void doshell(void);
static int inarray(gid_t, const gid_t[], int);
static void loginshell(void);
static void restoregrps(void);
static void usage(void);
static struct passwd *pwd;
static uid_t euid;
extern char **environ;
/* Manipulate effective user ID. */
#define PRIV_START do { \
if (seteuid(euid) < 0) \
err(1, "seteuid"); \
} while (0)
#define PRIV_END do { \
if (seteuid(getuid()) < 0) \
err(1, "seteuid"); \
} while (0)
int
main(int argc, char *argv[])
{
int ch, login;
euid = geteuid();
if (seteuid(getuid()) < 0)
err(1, "seteuid");
if ((pwd = getpwuid(getuid())) == NULL)
errx(1, "unknown user");
login = 0;
while ((ch = getopt(argc, argv, "-l")) != -1) {
switch (ch) {
case '-': /* Obsolescent */
case 'l':
login = 1;
break;
default:
usage();
}
}
argc -= optind;
argv += optind;
switch (argc) {
case 0:
restoregrps();
break;
case 1:
addgroup(*argv);
break;
default:
usage();
}
if (seteuid(euid) < 0)
err(1, "seteuid");
if (setuid(getuid()) < 0)
err(1, "setuid");
if (login)
loginshell();
else
doshell();
/*NOTREACHED*/
exit(1);
}
static void
usage(void)
{
fprintf(stderr, "usage: newgrp [-l] [group]\n");
exit(1);
}
static void
restoregrps(void)
{
int initres, setres;
PRIV_START;
initres = initgroups(pwd->pw_name, pwd->pw_gid);
setres = setgid(pwd->pw_gid);
PRIV_END;
if (initres < 0)
warn("initgroups");
if (setres < 0)
warn("setgid");
}
static void
addgroup(const char *grpname)
{
gid_t *grps;
long lgid, ngrps_max;
int dbmember, i, ngrps;
gid_t egid;
struct group *grp;
char *ep, *pass, *cryptpw;
char **p;
egid = getegid();
/* Try it as a group name, then a group id. */
if ((grp = getgrnam(grpname)) == NULL)
if ((lgid = strtol(grpname, &ep, 10)) <= 0 || *ep != '\0' ||
(grp = getgrgid((gid_t)lgid)) == NULL ) {
warnx("%s: bad group name", grpname);
return;
}
/*
* If the user is not a member of the requested group and the group
* has a password, prompt and check it.
*/
dbmember = 0;
if (pwd->pw_gid == grp->gr_gid)
dbmember = 1;
for (p = grp->gr_mem; *p != NULL; p++)
if (strcmp(*p, pwd->pw_name) == 0) {
dbmember = 1;
break;
}
if (!dbmember && *grp->gr_passwd != '\0' && getuid() != 0) {
pass = getpass("Password:");
if (pass == NULL)
return;
cryptpw = crypt(pass, grp->gr_passwd);
if (cryptpw == NULL || strcmp(grp->gr_passwd, cryptpw) != 0) {
fprintf(stderr, "Sorry\n");
return;
}
}
ngrps_max = sysconf(_SC_NGROUPS_MAX) + 1;
if ((grps = malloc(sizeof(gid_t) * ngrps_max)) == NULL)
err(1, "malloc");
if ((ngrps = getgroups(ngrps_max, (gid_t *)grps)) < 0) {
warn("getgroups");
goto end;
}
/* Remove requested gid from supp. list if it exists. */
if (grp->gr_gid != egid && inarray(grp->gr_gid, grps, ngrps)) {
for (i = 0; i < ngrps; i++)
if (grps[i] == grp->gr_gid)
break;
ngrps--;
memmove(&grps[i], &grps[i + 1], (ngrps - i) * sizeof(gid_t));
PRIV_START;
if (setgroups(ngrps, (const gid_t *)grps) < 0) {
PRIV_END;
warn("setgroups");
goto end;
}
PRIV_END;
}
PRIV_START;
if (setgid(grp->gr_gid)) {
PRIV_END;
warn("setgid");
goto end;
}
PRIV_END;
grps[0] = grp->gr_gid;
/* Add old effective gid to supp. list if it does not exist. */
if (egid != grp->gr_gid && !inarray(egid, grps, ngrps)) {
if (ngrps == ngrps_max)
warnx("too many groups");
else {
grps[ngrps++] = egid;
PRIV_START;
if (setgroups(ngrps, (const gid_t *)grps)) {
PRIV_END;
warn("setgroups");
goto end;
}
PRIV_END;
}
}
end:
free(grps);
}
static int
inarray(gid_t gid, const gid_t grps[], int ngrps)
{
int i;
for (i = 0; i < ngrps; i++)
if (grps[i] == gid)
return (1);
return (0);
}
/*
* Set the environment to what would be expected if the user logged in
* again; this performs the same steps as su(1)'s -l option.
*/
static void
loginshell(void)
{
char *args[2], **cleanenv, *term, *ticket;
const char *shell;
login_cap_t *lc;
shell = pwd->pw_shell;
if (*shell == '\0')
shell = _PATH_BSHELL;
if (chdir(pwd->pw_dir) < 0) {
warn("%s", pwd->pw_dir);
chdir("/");
}
term = getenv("TERM");
ticket = getenv("KRBTKFILE");
if ((cleanenv = calloc(20, sizeof(char *))) == NULL)
err(1, "calloc");
*cleanenv = NULL;
environ = cleanenv;
lc = login_getpwclass(pwd);
setusercontext(lc, pwd, pwd->pw_uid,
LOGIN_SETPATH|LOGIN_SETUMASK|LOGIN_SETENV);
login_close(lc);
setenv("USER", pwd->pw_name, 1);
setenv("SHELL", shell, 1);
setenv("HOME", pwd->pw_dir, 1);
if (term != NULL)
setenv("TERM", term, 1);
if (ticket != NULL)
setenv("KRBTKFILE", ticket, 1);
if (asprintf(args, "-%s", basename(shell)) < 0)
err(1, "asprintf");
args[1] = NULL;
execv(shell, args);
err(1, "%s", shell);
}
static void
doshell(void)
{
const char *shell;
shell = pwd->pw_shell;
if (*shell == '\0')
shell = _PATH_BSHELL;
execl(shell, basename(shell), (char *)NULL);
err(1, "%s", shell);
}