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/* vi: set sw=4 ts=4:
*
* passwd.c - Program to upadte user password.
*
* Copyright 2012 Ashwini Kumar <ak.ashwini@gmail.com>
* Modified 2012 Jason Kyungwan Han <asura321@gmail.com>
*
* http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/passwd.html
USE_PASSWD(NEWTOY(passwd, ">1a:dlu", TOYFLAG_STAYROOT|TOYFLAG_USR|TOYFLAG_BIN))
config PASSWD
bool "passwd"
default y
help
usage: passwd [-a ALGO] [-d] [-l] [-u] <account name>
update user’s authentication tokens. Default : current user
-a ALGO Encryption method (des, md5, sha256, sha512) default: des
-d Set password to ''
-l Lock (disable) account
-u Unlock (enable) account
*/
#include "toys.h"
#include <time.h>
DEFINE_GLOBALS(
char *algo;
)
#define TT this.passwd
#define FLAG_u (1 << 0)
#define FLAG_l (1 << 1)
#define FLAG_d (1 << 2)
#define FLAG_a (1 << 3)
#define MAX_SALT_LEN 20 //3 for id, 16 for key, 1 for '\0'
#define URANDOM_PATH "/dev/urandom"
#ifndef _GNU_SOURCE
char *strcasestr(const char *haystack, const char *needle);
#endif
unsigned int random_number_generator(int fd)
{
unsigned int randnum;
xreadall(fd, &randnum, sizeof(randnum));
return randnum;
}
char inttoc(int i)
{
// salt value uses 64 chracters in "./0-9a-zA-Z"
const char character_set[]="./0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
i &= 0x3f; // masking for using 10 bits only
return character_set[i];
}
int get_salt(char *salt)
{
int i, salt_length = 0;
int randfd;
if(!strncmp(TT.algo,"des",3)){
// 2 bytes salt value is used in des
salt_length = 2;
} else {
*salt++ = '$';
if(!strncmp(TT.algo,"md5",3)){
*salt++ = '1';
// 8 bytes salt value is used in md5
salt_length = 8;
} else if(!strncmp(TT.algo,"sha256",6)){
*salt++ = '5';
// 16 bytes salt value is used in sha256
salt_length = 16;
} else if(!strncmp(TT.algo,"sha512",6)){
*salt++ = '6';
// 16 bytes salt value is used in sha512
salt_length = 16;
} else return 1;
*salt++ = '$';
}
randfd = xopen(URANDOM_PATH, O_RDONLY);
for(i=0; i<salt_length; i++)
salt[i] = inttoc(random_number_generator(randfd));
salt[salt_length+1] = '\0';
xclose(randfd);
return 0;
}
static int str_check(char *s, char *p)
{
if((strcasestr(s, p) != NULL) || (strcasestr(p, s) != NULL))
return 1;
return 0;
}
static void strength_check(char *newp, char *oldp, char *user)
{
char *msg = NULL;
if(strlen(newp) < 6) { //Min passwd len
msg = "too short";
xprintf("BAD PASSWORD: %s\n",msg);
}
if(!newp[0])
return; //passwd is empty
if(str_check(newp, user)) {
msg = "user based password";
xprintf("BAD PASSWORD: %s\n",msg);
}
if(oldp[0] && str_check(newp, oldp)) {
msg = "based on old passwd";
xprintf("BAD PASSWORD: %s\n",msg);
}
}
static int verify_passwd(char * pwd)
{
char * pass;
if (!pwd) return 1;
if (pwd[0] == '!' || pwd[0] == '*') return 1;
pass = crypt(toybuf, pwd);
if (pass != NULL && strcmp(pass, pwd)==0)
return 0;
return 1;
}
static char *new_password(char *oldp, char *user)
{
char *newp = NULL;
if(read_password(toybuf, sizeof(toybuf), "New password:"))
return NULL; //may be due to Ctrl-C
newp = xstrdup(toybuf);
strength_check(newp, oldp, user);
if(read_password(toybuf, sizeof(toybuf), "Retype password:")) {
free(newp);
return NULL; //may be due to Ctrl-C
}
if(strcmp(newp, toybuf) == 0)
return newp;
else error_msg("Passwords do not match.\n");
/*Failure Case */
free(newp);
return NULL;
}
void passwd_main(void)
{
uid_t myuid;
struct passwd *pw;
struct spwd *sp;
char *name = NULL;
char *pass = NULL, *encrypted = NULL, *newp = NULL;
char *orig = (char *)"";
char salt[MAX_SALT_LEN];
int ret = -1;
myuid = getuid();
if((myuid != 0) && (toys.optflags & (FLAG_l | FLAG_u | FLAG_d)))
error_exit("You need to be root to do these actions\n");
pw = getpwuid(myuid);
if(!pw)
error_exit("Unknown uid '%u'",myuid);
if(toys.optargs[0])
name = toys.optargs[0];
else
name = xstrdup(pw->pw_name);
pw = getpwnam(name);
if(!pw) error_exit("Unknown user '%s'",name);
if(myuid != 0 && (myuid != pw->pw_uid))
error_exit("You need to be root to change '%s' password\n", name);
pass = pw->pw_passwd;
if(pw->pw_passwd[0] == 'x') {
/*get shadow passwd */
sp = getspnam(name);
if(sp)
pass = sp->sp_pwdp;
}
if(!(toys.optflags & (FLAG_l | FLAG_u | FLAG_d))) {
printf("Changing password for %s\n",name);
if(pass[0] == '!')
error_exit("Can't change, password is locked for %s",name);
if(myuid != 0) {
/*Validate user */
if(read_password(toybuf, sizeof(toybuf), "Origial password:")) {
if(!toys.optargs[0]) free(name);
return;
}
orig = toybuf;
if(verify_passwd(pass))
error_exit("Authentication failed\n");
}
orig = xstrdup(orig);
/*Get new password */
newp = new_password(orig, name);
if(!newp) {
free(orig);
if(!toys.optargs[0]) free(name);
return; //new password is not set well.
}
/*Encrypt the passwd */
if(!(toys.optflags & FLAG_a)) TT.algo = "des";
if(get_salt(salt))
error_exit("Error: Unkown encryption algorithm\n");
encrypted = crypt(newp, salt);
free(newp);
free(orig);
}
else if(toys.optflags & FLAG_l) {
if(pass[0] == '!')
error_exit("password is already locked for %s",name);
printf("Locking password for %s\n",name);
encrypted = xmsprintf("!%s",pass);
}
else if(toys.optflags & FLAG_u) {
if(pass[0] != '!')
error_exit("password is already unlocked for %s",name);
printf("Unlocking password for %s\n",name);
encrypted = xstrdup(&pass[1]);
}
else if(toys.optflags & FLAG_d) {
printf("Deleting password for %s\n",name);
encrypted = (char*)xzalloc(sizeof(char)*2); //1 = "", 2 = '\0'
}
/*Update the passwd */
if(pw->pw_passwd[0] == 'x')
ret = update_password("/etc/shadow", name, encrypted);
else
ret = update_password("/etc/passwd", name, encrypted);
if((toys.optflags & (FLAG_l | FLAG_u | FLAG_d)))
free(encrypted);
if(!toys.optargs[0]) free(name);
if(!ret)
error_msg("Success");
else
error_msg("Failure");
}
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