238 lines
6 KiB
C
238 lines
6 KiB
C
/*
|
|
* Copyright (c) 2015, 2023 Jonas 'Sortie' Termansen.
|
|
*
|
|
* 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.
|
|
*
|
|
* passwd.c
|
|
* Password change.
|
|
*/
|
|
|
|
#include <sys/termmode.h>
|
|
#include <sys/types.h>
|
|
|
|
#include <err.h>
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <pwd.h>
|
|
#include <stdbool.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <termios.h>
|
|
#include <unistd.h>
|
|
|
|
static void password(char* buffer,
|
|
size_t buffer_size,
|
|
const char* whose,
|
|
const char* question,
|
|
bool require_tty)
|
|
{
|
|
bool is_tty = isatty(0);
|
|
if ( !require_tty && is_tty )
|
|
errx(1, "Input is not a terminal");
|
|
unsigned int termmode = 0;
|
|
if ( is_tty )
|
|
{
|
|
gettermmode(0, &termmode);
|
|
settermmode(0, termmode & ~TERMMODE_ECHO);
|
|
if ( whose )
|
|
printf("%s's ", whose);
|
|
printf("%s ", question);
|
|
fflush(stdout);
|
|
fflush(stdin);
|
|
}
|
|
// TODO: This may leave a copy of the password in the stdio buffer.
|
|
fgets(buffer, buffer_size, stdin);
|
|
if ( is_tty )
|
|
{
|
|
fflush(stdin);
|
|
printf("\n");
|
|
settermmode(0, termmode);
|
|
}
|
|
size_t buffer_length = strlen(buffer);
|
|
if ( buffer_length && buffer[buffer_length-1] == '\n' )
|
|
buffer[--buffer_length] = '\0';
|
|
}
|
|
|
|
int main(int argc, char* argv[])
|
|
{
|
|
const char* cipher = "blowfish,a";
|
|
bool hash_password = false;
|
|
|
|
int opt;
|
|
while ( (opt = getopt(argc, argv, "c:H")) != -1 )
|
|
{
|
|
switch ( opt )
|
|
{
|
|
case 'c': cipher = optarg; break;
|
|
case 'H': hash_password = true; break;
|
|
default: return 1;
|
|
}
|
|
}
|
|
|
|
if ( hash_password )
|
|
{
|
|
if ( argc - optind )
|
|
errx(1, "Unexpected extra operand");
|
|
char pass[128];
|
|
password(pass, sizeof(pass), NULL, "Enter password (will not echo)",
|
|
false);
|
|
fgets(pass, sizeof(pass), stdin);
|
|
char newhash[128];
|
|
if ( crypt_newhash(pass, cipher, newhash, sizeof(newhash)) < 0 )
|
|
err(1, "crypt_newhash");
|
|
if ( printf("%s\n", newhash) < 0 || fflush(stdout) == EOF )
|
|
err(1, "stdout");
|
|
return 0;
|
|
}
|
|
|
|
uid_t my_uid = getuid();
|
|
char* my_username = getlogin();
|
|
if ( !my_username )
|
|
err(1, "failed to get username");
|
|
if ( !(my_username = strdup(my_username)) )
|
|
err(1, "stdup");
|
|
|
|
const char* username;
|
|
if ( argc - optind < 1 )
|
|
username = my_username;
|
|
else if ( argc - optind <= 1 )
|
|
username = argv[optind];
|
|
else
|
|
errx(1, "Unexpected extra operand");
|
|
|
|
errno = 0;
|
|
struct passwd* pwd = getpwnam(username);
|
|
if ( !pwd && errno == 0 )
|
|
errx(1, "%s: No such user", username);
|
|
if ( !pwd )
|
|
err(1, "%s", username);
|
|
|
|
if ( my_uid != 0 && pwd->pw_uid != my_uid )
|
|
errx(1, "You may not change the password for '%s'", username);
|
|
|
|
printf("Changing password for %s.\n", username);
|
|
|
|
if ( my_uid != 0 )
|
|
{
|
|
char current[128];
|
|
password(current, sizeof(current), pwd->pw_name,
|
|
"current password (will not echo)", true);
|
|
if ( crypt_checkpass(current, pwd->pw_passwd) < 0 )
|
|
errx(1, "Wrong password for '%s'", pwd->pw_name);
|
|
explicit_bzero(current, sizeof(current));
|
|
}
|
|
|
|
char first[128];
|
|
password(first, sizeof(first), NULL, "Enter new password (will not echo)",
|
|
true);
|
|
char second[128];
|
|
password(second, sizeof(second), NULL, "Enter new password (again)", true);
|
|
if ( strcmp(first, second) != 0 )
|
|
errx(1, "Passwords don't match");
|
|
explicit_bzero(second, sizeof(second));
|
|
char newhash[128];
|
|
if ( crypt_newhash(first, cipher, newhash, sizeof(newhash)) < 0 )
|
|
err(1, "crypt_newhash");
|
|
explicit_bzero(first, sizeof(first));
|
|
// TODO: This is subject to races and is obviously an insecure design.
|
|
// The backend and coordination of the passwd database should be moved
|
|
// to its own daemon.
|
|
FILE* in = fopen("/etc/passwd", "r");
|
|
if ( !in )
|
|
err(1, "/etc/passwd");
|
|
int fd = open("/etc/passwd.new", O_WRONLY | O_CREAT | O_EXCL, 0644);
|
|
if ( fd < 0 )
|
|
err(1, "/etc/passwd.new");
|
|
fchown(fd, 0, 0); // HACK.
|
|
FILE* fp = fdopen(fd, "w");
|
|
if ( !fp )
|
|
{
|
|
unlink("/etc/passwd.new");
|
|
err(1, "fdopen");
|
|
}
|
|
char* line = NULL;
|
|
size_t size = 0;
|
|
ssize_t length;
|
|
bool found = false;
|
|
while ( 0 < (length = getline(&line, &size, in)) )
|
|
{
|
|
char* copy = strdup(line);
|
|
if ( !copy )
|
|
{
|
|
unlink("/etc/passwd.new");
|
|
err(1, "malloc");
|
|
}
|
|
if ( copy[length - 1] == '\n' )
|
|
copy[--length] = '\0';
|
|
struct passwd passwd;
|
|
if ( !scanpwent(copy, (pwd = &passwd)) )
|
|
{
|
|
fputs(line, fp);
|
|
free(copy);
|
|
continue;
|
|
}
|
|
fputs(pwd->pw_name, fp);
|
|
fputc(':', fp);
|
|
if ( !strcmp(pwd->pw_name, username) )
|
|
{
|
|
fputs(newhash, fp);
|
|
found = true;
|
|
}
|
|
else
|
|
fputs(pwd->pw_passwd, fp);
|
|
fputc(':', fp);
|
|
fprintf(fp, "%" PRIuUID, pwd->pw_uid);
|
|
fputc(':', fp);
|
|
fprintf(fp, "%" PRIuGID, pwd->pw_gid);
|
|
fputc(':', fp);
|
|
fputs(pwd->pw_gecos, fp);
|
|
fputc(':', fp);
|
|
fputs(pwd->pw_dir, fp);
|
|
fputc(':', fp);
|
|
fputs(pwd->pw_shell, fp);
|
|
fputc('\n', fp);
|
|
if ( ferror(fp) || fflush(stdout) == EOF )
|
|
{
|
|
unlink("/etc/passwd.new");
|
|
err(1, "/etc/passwd.new");
|
|
}
|
|
free(copy);
|
|
}
|
|
free(line);
|
|
if ( ferror(in) )
|
|
{
|
|
unlink("/etc/passwd.new");
|
|
err(1, "/etc/passwd");
|
|
}
|
|
fclose(in);
|
|
if ( ferror(fp) || fclose(fp) == EOF )
|
|
{
|
|
unlink("/etc/passwd.new");
|
|
err(1, "/etc/passwd.new");
|
|
}
|
|
if ( !found )
|
|
{
|
|
unlink("/etc/passwd.new");
|
|
errx(1, "user %s is not directly in /etc/passwd", username);
|
|
}
|
|
if ( rename("/etc/passwd.new", "/etc/passwd") < 0 )
|
|
{
|
|
unlink("/etc/passwd.new");
|
|
err(1, "rename: /etc/passwd.new -> /etc/passwd");
|
|
}
|
|
|
|
printf("Changed password for %s.\n", username);
|
|
|
|
return 0;
|
|
}
|