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ubase/su.c

94 lines
1.7 KiB
C

/* See LICENSE file for copyright and license details. */
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#include <pwd.h>
#include <grp.h>
#include <shadow.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "util.h"
static void
usage(void)
{
eprintf("usage: %s [username]\n", argv0);
}
int
main(int argc, char **argv)
{
char *usr, *pass, *cryptpass;
char * const *newargv;
struct spwd *spw;
struct passwd *pw;
uid_t uid;
int i;
ARGBEGIN {
default:
usage();
} ARGEND;
if (argc < 1)
usr = "root";
else if (argc == 1)
usr = argv[0];
else
usage();
uid = getuid();
errno = 0;
spw = getspnam(usr);
if (errno)
eprintf("getspnam: %s:", usr);
else if (!spw)
enprintf(EXIT_FAILURE, "who are you?\n");
switch (spw->sp_pwdp[0]) {
case '!':
case '*':
enprintf(EXIT_FAILURE, "Denied\n");
case '$':
break;
default:
enprintf(EXIT_FAILURE, "Invalid shadow record\n");
}
if (uid) {
pass = getpass("Password: ");
if (!pass)
eprintf("getpass:");
cryptpass = crypt(pass, spw->sp_pwdp);
for (i = 0; pass[i]; i++)
pass[i] = '\0';
if (!cryptpass)
eprintf("crypt:");
if (strcmp(cryptpass, spw->sp_pwdp) != 0)
enprintf(EXIT_FAILURE, "Denied\n");
}
errno = 0;
pw = getpwnam(usr);
if (errno)
eprintf("getpwnam: %s", usr);
else if (!pw)
enprintf(EXIT_FAILURE, "who are you?\n");
if (initgroups(usr, pw->pw_gid) < 0)
eprintf("initgroups:");
if (setgid(pw->pw_gid) < 0)
eprintf("setgid:");
if (setuid(pw->pw_uid) < 0)
eprintf("setuid:");
newargv = (char *const[]){pw->pw_shell, NULL};
setenv("HOME", pw->pw_dir, 1);
execve(pw->pw_shell, newargv, environ);
return (errno == ENOENT) ? 127 : 126;
}