ubase/su.c

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C
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/* See LICENSE file for copyright and license details. */
#include <sys/types.h>
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#include <errno.h>
#include <grp.h>
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#include <pwd.h>
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#include <stdio.h>
#include <stdlib.h>
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#include <string.h>
#include <unistd.h>
#include "config.h"
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#include "passwd.h"
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#include "util.h"
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extern char **environ;
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static int dologin(struct passwd *);
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static void
usage(void)
{
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eprintf("usage: %s [-lp] [username]\n", argv0);
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}
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static int lflag = 0;
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static int pflag = 0;
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int
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main(int argc, char *argv[])
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{
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char *usr = "root", *pass;
char *shell;
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struct passwd *pw;
char *newargv[2];
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uid_t uid;
ARGBEGIN {
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case 'l':
lflag = 1;
break;
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case 'p':
pflag = 1;
break;
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default:
usage();
} ARGEND;
if (argc < 1)
;
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else if (argc == 1)
usr = argv[0];
else
usage();
errno = 0;
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pw = getpwnam(usr);
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if (!pw) {
if (errno)
eprintf("getpwnam: %s:", usr);
else
eprintf("who are you?\n");
}
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uid = getuid();
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if (uid) {
pass = getpass("Password: ");
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if (!pass)
eprintf("getpass:");
if (pw_check(pw, pass) <= 0)
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exit(1);
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}
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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:");
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if (lflag) {
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return dologin(pw);
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} else {
shell = pw->pw_shell[0] == '\0' ? "/bin/sh" : pw->pw_shell;
newargv[0] = shell;
newargv[1] = NULL;
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if (!pflag) {
setenv("HOME", pw->pw_dir, 1);
setenv("SHELL", shell, 1);
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if (strcmp(pw->pw_name, "root") != 0) {
setenv("USER", pw->pw_name, 1);
setenv("LOGNAME", pw->pw_name, 1);
}
}
if (strcmp(pw->pw_name, "root") == 0)
setenv("PATH", ENV_SUPATH, 1);
else
setenv("PATH", ENV_PATH, 1);
execve(pflag ? getenv("SHELL") : shell,
newargv, environ);
weprintf("execve %s:", shell);
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return (errno == ENOENT) ? 127 : 126;
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}
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return 0;
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}
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static int
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dologin(struct passwd *pw)
{
char *shell = pw->pw_shell[0] == '\0' ? "/bin/sh" : pw->pw_shell;
char *term = getenv("TERM");
clearenv();
setenv("HOME", pw->pw_dir, 1);
setenv("SHELL", shell, 1);
setenv("USER", pw->pw_name, 1);
setenv("LOGNAME", pw->pw_name, 1);
setenv("TERM", term ? term : "linux", 1);
if (strcmp(pw->pw_name, "root") == 0)
setenv("PATH", ENV_SUPATH, 1);
else
setenv("PATH", ENV_PATH, 1);
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if (chdir(pw->pw_dir) < 0)
eprintf("chdir %s:", pw->pw_dir);
execlp(shell, shell, "-l", NULL);
weprintf("execlp %s:", shell);
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return (errno == ENOENT) ? 127 : 126;
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}