From 49539a201d3f828536a92bafc7ccdb28acb66b02 Mon Sep 17 00:00:00 2001 From: Tomas Mraz Date: Thu, 4 Nov 2004 11:44:56 +0000 Subject: [PATCH] Relevant BUGIDs: Purpose of commit: bugfix Commit summary: --------------- Fix locking in pam_unix_passwd to avoid race on changing passwords --- modules/pam_unix/pam_unix_passwd.c | 117 +++++++++++++++++++---------- 1 file changed, 78 insertions(+), 39 deletions(-) diff --git a/modules/pam_unix/pam_unix_passwd.c b/modules/pam_unix/pam_unix_passwd.c index 4e90b764..71695276 100644 --- a/modules/pam_unix/pam_unix_passwd.c +++ b/modules/pam_unix/pam_unix_passwd.c @@ -533,8 +533,11 @@ static int _do_setpass(pam_handle_t* pamh, const char *forwho, char *fromwhat, D(("called")); pwd = getpwnam(forwho); - if (pwd == NULL) - return PAM_AUTHTOK_ERR; + + if (pwd == NULL) { + retval = PAM_AUTHTOK_ERR; + goto done; + } if (on(UNIX_NIS, ctrl) && _unix_comesfromsource(pamh, forwho, 0, 1)) { struct timeval timeout; @@ -544,6 +547,10 @@ static int _do_setpass(pam_handle_t* pamh, const char *forwho, char *fromwhat, int status; int err = 0; + /* Unlock passwd file to avoid deadlock */ +#ifdef USE_LCKPWDF + ulckpwdf(); +#endif /* Make RPC call to NIS server */ if ((master = getNISserver(pamh)) == NULL) return PAM_TRY_AGAIN; @@ -600,42 +607,26 @@ static int _do_setpass(pam_handle_t* pamh, const char *forwho, char *fromwhat, } /* first, save old password */ if (save_old_password(pamh, forwho, fromwhat, remember)) { - return PAM_AUTHTOK_ERR; + retval = PAM_AUTHTOK_ERR; + goto done; } - -#ifdef USE_LCKPWDF - /* - * These values for the number of attempts and the sleep time - * are, of course, completely arbitrary. - * - * My reading of the PAM docs is that, once pam_chauthtok() - * has been called with PAM_UPDATE_AUTHTOK, we are obliged to - * take any reasonable steps to make sure the token is - * updated; so retrying for 1/10 sec. isn't overdoing it. - */ - - retval = lckpwdf(); - if (retval != 0) { - return PAM_AUTHTOK_LOCK_BUSY; + if (_unix_comesfromsource(pamh, forwho, 1, 0)) { + if (on(UNIX_SHADOW, ctrl) || _unix_shadowed(pwd)) { + retval = _update_shadow(pamh, forwho, towhat); + if (retval != PAM_SUCCESS && SELINUX_ENABLED) + retval = _unix_run_shadow_binary(pamh, ctrl, forwho, fromwhat, towhat); + if (retval == PAM_SUCCESS) + if (!_unix_shadowed(pwd)) + retval = _update_passwd(pamh, forwho, "x"); + } else { + retval = _update_passwd(pamh, forwho, towhat); + } } -#endif /* def USE_LCKPWDF */ - - if (_unix_comesfromsource (pamh, forwho, 1, 0)) - { - if (on(UNIX_SHADOW, ctrl) || _unix_shadowed (pwd)) - { - retval = _update_shadow (pamh, forwho, towhat); - if (retval == PAM_SUCCESS) - if (!_unix_shadowed (pwd)) - retval = _update_passwd (pamh, forwho, "x"); - } - else - retval = _update_passwd (pamh, forwho, towhat); - } +done: #ifdef USE_LCKPWDF ulckpwdf(); -#endif /* def USE_LCKPWDF */ +#endif return retval; } @@ -762,7 +753,7 @@ PAM_EXTERN int pam_sm_chauthtok(pam_handle_t * pamh, int flags, int argc, const char **argv) { unsigned int ctrl, lctrl; - int retval; + int retval, i; int remember = -1; /* */ @@ -937,11 +928,7 @@ PAM_EXTERN int pam_sm_chauthtok(pam_handle_t * pamh, int flags, _log_err(LOG_NOTICE, pamh, "user not authenticated"); return retval; } - retval = _unix_verify_shadow(user, ctrl); - if (retval != PAM_SUCCESS) { - _log_err(LOG_NOTICE, pamh, "user not authenticated 2"); - return retval; - } + D(("get new password now")); lctrl = ctrl; @@ -992,6 +979,54 @@ PAM_EXTERN int pam_sm_chauthtok(pam_handle_t * pamh, int flags, pass_new = pass_old = NULL; /* tidy up */ return retval; } +#ifdef USE_LCKPWDF + /* These values for the number of attempts and the sleep time + are, of course, completely arbitrary. + My reading of the PAM docs is that, once pam_chauthtok() has been + called with PAM_UPDATE_AUTHTOK, we are obliged to take any + reasonable steps to make sure the token is updated; so retrying + for 1/10 sec. isn't overdoing it. */ + i=0; + while((retval = lckpwdf()) != 0 && i < 100) { + usleep(1000); + i++; + } + if(retval != 0) { + return PAM_AUTHTOK_LOCK_BUSY; + } +#endif + + if (pass_old) { + retval = _unix_verify_password(pamh, user, pass_old, ctrl); + if (retval != PAM_SUCCESS) { + _log_err(LOG_NOTICE, pamh, "user password changed by another process"); +#ifdef USE_LCKPWDF + ulckpwdf(); +#endif + return retval; + } + } + + retval = _unix_verify_shadow(user, ctrl); + if (retval != PAM_SUCCESS) { + _log_err(LOG_NOTICE, pamh, "user not authenticated 2"); +#ifdef USE_LCKPWDF + ulckpwdf(); +#endif + return retval; + } + + retval = _pam_unix_approve_pass(pamh, ctrl, pass_old, pass_new); + if (retval != PAM_SUCCESS) { + _log_err(LOG_NOTICE, pamh, + "new password not acceptable 2"); + pass_new = pass_old = NULL; /* tidy up */ +#ifdef USE_LCKPWDF + ulckpwdf(); +#endif + return retval; + } + /* * By reaching here we have approved the passwords and must now * rebuild the password database file. @@ -1030,6 +1065,9 @@ PAM_EXTERN int pam_sm_chauthtok(pam_handle_t * pamh, int flags, _log_err(LOG_CRIT, pamh, "out of memory for password"); pass_new = pass_old = NULL; /* tidy up */ +#ifdef USE_LCKPWDF + ulckpwdf(); +#endif return PAM_BUF_ERR; } /* copy first 8 bytes of password */ @@ -1051,6 +1089,7 @@ PAM_EXTERN int pam_sm_chauthtok(pam_handle_t * pamh, int flags, retval = _do_setpass(pamh, user, pass_old, tpass, ctrl, remember); + /* _do_setpass has called ulckpwdf for us */ _pam_delete(tpass); pass_old = pass_new = NULL; -- 2.40.0