ubase/su.c

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C
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/* 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 "config.h"
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#include "util.h"
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extern char **environ;
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static char *msetenv(const char *, const char *);
static void 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
main(int argc, char **argv)
{
char *usr = "root", *pass, *cryptpass;
char * const *newargv;
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struct spwd *spw;
struct passwd *pw;
uid_t uid;
int i;
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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spw = getspnam(usr);
if (errno)
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eprintf("getspnam: %s:", usr);
else if (!spw)
eprintf("who are you?\n");
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switch (spw->sp_pwdp[0]) {
case '!':
case '*':
eprintf("Denied\n");
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case '$':
break;
default:
eprintf("Invalid shadow record\n");
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}
uid = getuid();
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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:");
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if (strcmp(cryptpass, spw->sp_pwdp) != 0)
eprintf("Denied\n");
}
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errno = 0;
pw = getpwnam(usr);
if (errno)
eprintf("getpwnam: %s", usr);
else if (!pw)
eprintf("who are you?\n");
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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) {
dologin(pw);
} else {
newargv = (char *const[]){pw->pw_shell, NULL};
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if (!pflag) {
setenv("HOME", pw->pw_dir, 1);
setenv("SHELL", pw->pw_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") : pw->pw_shell,
newargv, environ);
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}
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return (errno == ENOENT) ? 127 : 126;
}
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static char *
msetenv(const char *name, const char *value)
{
char *buf;
size_t sz;
sz = strlen(name) + strlen(value) + 2;
buf = malloc(sz);
if (!buf)
eprintf("malloc:");
snprintf(buf, sz, "%s=%s", name, value);
return buf;
}
static void
dologin(struct passwd *pw)
{
char shbuf[strlen(pw->pw_shell) + 1];
char * const *newargv;
char * const *newenv;
strcpy(shbuf, pw->pw_shell);
newargv = (char *const[]){shbuf, NULL};
newenv = (char *const[]){
msetenv("HOME", pw->pw_dir),
msetenv("SHELL", pw->pw_shell),
msetenv("USER", pw->pw_name),
msetenv("LOGNAME", pw->pw_name),
msetenv("TERM", getenv("TERM")),
msetenv("PATH",
strcmp(pw->pw_name, "root") == 0 ?
ENV_SUPATH : ENV_PATH),
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NULL
};
if (chdir(pw->pw_dir) < 0)
eprintf("chdir %s:", pw->pw_dir);
execve(pw->pw_shell, newargv, newenv);
}