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#define _XOPEN_SOURCE
#include <pwd.h>
#include <netdb.h>
#include <sys/types.h>
#include <unistd.h>
#include <time.h>
#include <string.h>
#ifndef MAXHOSTNAMELEN
# define MAXHOSTNAMELEN 256
#endif
#define PAM_SM_AUTH
#define PAM_SM_ACCOUNT
#define PAM_PASSWORD
#ifndef __linux__
#include <login_cap.h> /* for BSD login classes */
#else
#include <shadow.h> /* for linux boxes */
#endif
#define PASSWORD_HASH "md5"
#define MAX_RETRIES 3
#define DEFAULT_WARN (2L * 7L * 86400L) /* two weeks */
#define SALTSIZE 32
#include <security/pam_modules.h>
#include <security/pam_appl.h>
#include <security/pam_mod_misc.h>
static char * read_shadow(const char * user) ;
/*
* User authentication
*/
PAM_EXTERN int
pam_sm_authenticate(pam_handle_t *pamh, int flags,
int argc , const char **argv ) {
#ifndef __linux__
login_cap_t *lc;
#endif
struct passwd *pwd;
const char *pass, *crypt_pass, *real_hash, *user;
int pam_err;
/* identify user */
if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF)) {
PAM_LOG("Authenticating as self.");
pwd = getpwnam(getlogin());
} else {
if ((pam_err = pam_get_user(pamh, &user, NULL)) != PAM_SUCCESS) {
PAM_ERROR("Authenticating with uname [%s] failed.", user);
return (pam_err);
}
pwd = getpwnam(user);
}
PAM_LOG("Authenticating user: [%s]", user);
puts("USER GOT");
/* get password */
if (pwd != NULL) {
PAM_LOG("Doing real authentication");
pass = pwd->pw_passwd;
if (pass[0] == '\0') {
if (!(flags & PAM_DISALLOW_NULL_AUTHTOK) &&
openpam_get_option(pamh, PAM_OPT_NULLOK)){
PAM_LOG("User [%s] has empty password. Authentication succesfull.");
return (PAM_SUCCESS);
}
real_hash = "*";
}
/*
* Dummy authentication is something that the freebsd-lib
* people have implemented. Not sure whether it's needed on
* Linux -or BSD- but it'll be left as is for compatibiity
* issues. Need to be checked!
*/
lc = login_getpwclass(pwd);
} else {
PAM_LOG("Doing dummy authentication.");
real_hash = "*";
#ifndef __linux__
lc = login_getpwclass(NULL);
#endif
}
#ifndef __linux__
prompt = login_getcapstr(lc, "passwd_prompt", NULL, NULL);
pam_err = pam_get_authtok(pamh, PAM_AUTHTOK, &pass, prompt);
login_close(lc);
#else
pam_err = pam_get_authtok(pamh, PAM_AUTHTOK, (const char **) &pass, NULL);
#endif
PAM_LOG("Got password for user [%s]", user);
if (pam_err == PAM_CONV_ERR)
return (pam_err);
if (pam_err != PAM_SUCCESS)
return (PAM_AUTH_ERR);
/* check passwd entry */
if ( strncmp(real_hash, "*", sizeof(char)) !=0 ) {
#ifndef __linux__
real_hash = pwd->pw_passwd;
#else
real_hash = read_shadow(user);
#endif
}
crypt_pass = crypt(pass,real_hash);
if ( strcmp(crypt_pass, real_hash) != 0 ) {
PAM_ERROR("Wrong password. Authentication failed.");
pam_err = PAM_AUTH_ERR;
} else {
PAM_LOG("Authentication completed succesfully.");
puts("SUCCESS!");
pam_err = PAM_SUCCESS;
}
return (pam_err);
}
PAM_EXTERN int
pam_sm_setcred(pam_handle_t *pamh , int flags ,
int argc , const char *argv[] ) {
/*
* This functions takes care of renewing/initializing
* user credentials as well as gid/uids. Someday, it
* will be completed. For now, it's not very urgent.
*/
return (PAM_SUCCESS);
}
/*
* Account Management
*/
PAM_EXTERN int
pam_sm_acct_mgmt(pam_handle_t *pamh, int flags ,
int argc , const char *argv[] ) {
#ifndef __linux__
login_cap_t *lc;
#endif
struct spwd *pwd;
int pam_err;
const char *user;
time_t curtime;
#ifndef __linux__
const void *rhost, *tty;
char rhostip[MAXHOSTNAMELEN] = "";
#endif
/* Sanity checks for uname,pwd,tty,host etc */
pam_err = pam_get_user(pamh, &user, NULL);
if (pam_err != PAM_SUCCESS)
return (pam_err);
if (user == NULL || (pwd = getpwnam(user)) == NULL)
return (PAM_SERVICE_ERR);
PAM_LOG("Got user [%s]" , user );
#ifndef __linux__
/*
* tty/host info are provided by login classes
* and cannot be used out of the box under Linux
* for sanity checking (BSD only). May need to
* be ported/rewritten to work on Linux as well.
* Time will tell...
*/
pam_err = pam_get_item(pamh, PAM_RHOST, &rhost);
if (pam_err != PAM_SUCCESS)
return (pam_err);
pam_err = pam_get_item(pamh, PAM_TTY, &tty);
if (pam_err != PAM_SUCCESS)
return (pam_err);
#endif
if (*pwd->sp_pwdp == '\0' &&
(flags & PAM_DISALLOW_NULL_AUTHTOK) != 0)
return (PAM_NEW_AUTHTOK_REQD);
#ifndef __linux__
lc = login_getpwclass(pwd);
if (lc == NULL) {
PAM_ERROR("Unable to get login class for user [%s]");
return (PAM_SERVICE_ERR);
}
#endif
/* Check if pw_lstchg or sp_expire is set */
if (pwd->sp_lstchg || pwd->sp_expire)
curtime = time(NULL) / (60 * 60 * 24);
if (pwd->sp_expire) {
if ( (curtime > pwd->sp_expire ) && ( pwd->sp_expire != -1 ) ) {
#ifndef __linux__
login_close(lc);
#endif
PAM_ERROR("Account has expired!");
return (PAM_ACCT_EXPIRED);
} else if ( ( pwd->sp_expire - curtime < DEFAULT_WARN) ) {
PAM_ERROR("Warning: your account expires on %s",
ctime(&pwd->sp_expire));
}
}
if (pwd->sp_lstchg == 0 ) {
return (PAM_NEW_AUTHTOK_REQD);
}
/* check all other possibilities (mostly stolen from pam_tcb) */
if ((curtime > (pwd->sp_lstchg + pwd->sp_max + pwd->sp_inact)) &&
(pwd->sp_max != -1) && (pwd->sp_inact != -1) &&
(pwd->sp_lstchg != 0)) {
PAM_ERROR("Account has expired!");
return (PAM_ACCT_EXPIRED);
}
if (((pwd->sp_lstchg + pwd->sp_max) < curtime) &&
(pwd->sp_max != -1)) {
PAM_ERROR("Account has expired!");
return (PAM_ACCT_EXPIRED);
}
if ((curtime - pwd->sp_lstchg > pwd->sp_max)
&& (curtime - pwd->sp_lstchg > pwd->sp_inact)
&& (curtime - pwd->sp_lstchg > pwd->sp_max + pwd->sp_inact)
&& (pwd->sp_max != -1) && (pwd->sp_inact != -1)) {
PAM_ERROR("Account has expired!");
return (PAM_ACCT_EXPIRED);
}
pam_err = (PAM_SUCCESS);
#ifndef __linux__
/* validate tty/host/time */
if (!auth_hostok(lc, rhost, rhostip) ||
!auth_ttyok(lc, tty) ||
!auth_timeok(lc, time(NULL)))
pam_err = PAM_AUTH_ERR;
login_close(lc);
#endif
return (pam_err);
}
/*
* Password Management
*/
PAM_EXTERN int
pam_sm_chautok(pam_handle_t *pamh, int flags,
int argc, const char *argv[])
{
/*
* NIS support will be left for future implementation.
* This is standard unix passwd changing function.
*/
struct passwd *new_pwd, *old_pwd;
const char *user, *old_pass, *new_pass;
char *hashedpwd ;
#ifndef __linux__
login_cap_t * lc;
#endif
int pam_err, retries;
/* identify user */
if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF)) {
PAM_LOG("Authenticating as self.");
user=getlogin();
old_pwd = getpwnam(user);
} else {
if ((pam_err = pam_get_user(pamh, &user, NULL)) != PAM_SUCCESS) {
PAM_ERROR("Authenticating with uname [%s] failed.", user);
return (pam_err);
}
old_pwd = getpwnam(user);
}
PAM_LOG("Got user: [%s]", user);
if (old_pwd == NULL) {
PAM_ERROR("User [%s] either has a corrupted passwd entry or \
is not in the selected database", user);
return (PAM_AUTHTOK_RECOVERY_ERR);
}
/*
* When looking through the LinuxPAM code, I came across this :
*
* ` Various libraries at various times have had bugs related to
* '+' or '-' as the first character of a user name. Don't
* allow them. `
*
* I don't know if the problem is still around but just in case...
*/
if (user == NULL || user[0] == '-' || user[0] == '+' ) {
PAM_ERROR("Bad username [%s]", user);
return (PAM_USER_UNKNOWN);
}
if (flags & PAM_PRELIM_CHECK) {
PAM_LOG("Doing preliminary actions.");
if (getuid() == 0 ) {
/* root doesn't need old passwd */
return (pam_set_item(pamh, PAM_OLDAUTHTOK, ""));
}
if ( (old_pwd->pw_passwd[0] == '\0' ) &&
( openpam_get_option(pamh, PAM_OPT_NULLOK) ) &&
!(flags & PAM_DISALLOW_NULL_AUTHTOK) ) {
/*
* Something funny could happen here since we don't
* ask for a password.
*/
old_pass = "";
} else {
pam_err = pam_get_authtok(pamh,PAM_OLDAUTHTOK,
&old_pass, NULL);
if (pam_err != PAM_SUCCESS )
return (pam_err);
}
PAM_LOG("Got old token for user [%s].",user);
hashedpwd = crypt(old_pass, old_pwd->pw_passwd);
if (old_pass[0] == '\0' && !openpam_get_option(pamh, PAM_OPT_NULLOK))
return (PAM_PERM_DENIED);
if (strcmp(hashedpwd, old_pwd->pw_passwd) != 0)
return (PAM_PERM_DENIED);
} else if ( flags & PAM_UPDATE_AUTHTOK ) {
PAM_LOG("Doing actual update.");
pam_err= pam_get_authtok(pamh, PAM_OLDAUTHTOK ,&old_pass, NULL);
if (pam_err != PAM_SUCCESS)
return (pam_err);
PAM_LOG("Got old password");
retries = 0;
pam_err = PAM_AUTHTOK_ERR;
while ((pam_err != PAM_SUCCESS) && ( retries++ < MAX_RETRIES)) {
pam_err = pam_get_authtok(pamh, PAM_AUTHTOK,
&new_pass, NULL);
pam_error(pamh, "Unable to get new passwd. Please \
try again");
}
if (pam_err != PAM_SUCCESS) {
PAM_ERROR("Unable to get new password!");
return (pam_err);
}
PAM_LOG("Got new password");
/*
* checking has to be done (?) for the new passwd to
* verify it's not weak.
*/
if (getuid() != 0 && new_pass[0] == '\0' &&
!openpam_get_option(pamh, PAM_OPT_NULLOK))
return (PAM_PERM_DENIED);
#ifndef __linux__
/*
* The BSD way to update the passwd entry. Taken as is
* from the freebsd-lib module pam_unix. Unfortunately,
* the following won't work under Linux.
*/
if ((new_pwd = pw_dup(old_pwd)) == NULL)
return (PAM_BUF_ERR);
new_pwd->pw_change = 0;
lc = login_getclass(new_pwd->pw_class);
if (login_setcryptfmt(lc, password_hash, NULL) == NULL)
openpam_log(PAM_LOG_ERROR,
"can't set password cipher, relying on default");
login_close(lc);
makesalt(salt);
new_pwd->pw_passwd = crypt(new_pass, salt);
pam_err = PAM_SERVICE_ERR;
if (pw_init(NULL, NULL))
openpam_log(PAM_LOG_ERROR, "pw_init() failed");
else if ((pfd = pw_lock()) == -1)
openpam_log(PAM_LOG_ERROR, "pw_lock() failed");
else if ((tfd = pw_tmp(-1)) == -1)
openpam_log(PAM_LOG_ERROR, "pw_tmp() failed");
else if (pw_copy(pfd, tfd, new_pwd, old_pwd) == -1)
openpam_log(PAM_LOG_ERROR, "pw_copy() failed");
else if (pw_mkdb(new_pwd->pw_name) == -1)
openpam_log(PAM_LOG_ERROR, "pw_mkdb() failed");
else
pam_err = PAM_SUCCESS;
pw_fini();
free(old_pwd);
#endif
/* Update shadow/passwd entries for Linux */
} else {
pam_err = PAM_ABORT;
PAM_ERROR("Unrecognized flags.");
return (pam_err);
}
return (PAM_SUCCESS);
}
/*
* Read hashed password for user from shadow entry.
* This is for use on Linux machines only.
*/
static char * read_shadow(const char * user) {
struct spwd * pwd;
/*
* No error checking. Everything has been tested prior to
* calling this function. Nothing can go wrong, right?
*/
pwd = getspnam(user);
return (pwd->sp_pwdp);
}
#ifndef __linux__
/*
* Mostly stolen from freebsd-lib's pam_unix module which was mostly
* stolen from passwd(1)'s local_passwd.c
*
* Good ideas are meant to be reused ;)
*/
static unsigned char itoa64[] = /* 0 ... 63 => ascii - 64 */
"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
static void to64(char *s, long v, int n) {
while (--n >= 0) {
*s++ = itoa64[v&0x3f];
v >>= 6;
}
}
/* Salt suitable for traditional DES and MD5 */
void
makesalt(char salt[SALTSIZE]) {
int i;
/* These are not really random numbers, they are just
* numbers that change to thwart construction of a
* dictionary. This is exposed to the public.
*/
for (i = 0; i < SALTSIZE; i += 4)
// to64(&salt[i], arc4random(), 4);
salt[SALTSIZE] = '\0';
}
#endif
PAM_MODULE_ENTRY("pam_unix")
|