/* * Copyright (c) 2000 Damien Miller. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include "includes.h" #ifdef USE_PAM #include "xmalloc.h" #include "log.h" #include "auth.h" #include "auth-options.h" #include "auth-pam.h" #include "servconf.h" #include "canohost.h" #include "readpass.h" extern char *__progname; extern int use_privsep; RCSID("$Id: auth-pam.c,v 1.55.4.1 2003/04/29 09:12:08 djm Exp $"); #define NEW_AUTHTOK_MSG \ "Warning: Your password has expired, please change it now." #define NEW_AUTHTOK_MSG_PRIVSEP \ "Your password has expired, the session cannot proceed." static int do_pam_conversation(int num_msg, const struct pam_message **msg, struct pam_response **resp, void *appdata_ptr); /* module-local variables */ static struct pam_conv conv = { (int (*)())do_pam_conversation, NULL }; static char *__pam_msg = NULL; static pam_handle_t *__pamh = NULL; static const char *__pampasswd = NULL; /* states for do_pam_conversation() */ enum { INITIAL_LOGIN, OTHER } pamstate = INITIAL_LOGIN; /* remember whether pam_acct_mgmt() returned PAM_NEW_AUTHTOK_REQD */ static int password_change_required = 0; /* remember whether the last pam_authenticate() succeeded or not */ static int was_authenticated = 0; /* Remember what has been initialised */ static int session_opened = 0; static int creds_set = 0; /* accessor which allows us to switch conversation structs according to * the authentication method being used */ void do_pam_set_conv(struct pam_conv *conv) { pam_set_item(__pamh, PAM_CONV, conv); } /* start an authentication run */ int do_pam_authenticate(int flags) { int retval = pam_authenticate(__pamh, flags); was_authenticated = (retval == PAM_SUCCESS); return retval; } /* * PAM conversation function. * There are two states this can run in. * * INITIAL_LOGIN mode simply feeds the password from the client into * PAM in response to PAM_PROMPT_ECHO_OFF, and collects output * messages with into __pam_msg. This is used during initial * authentication to bypass the normal PAM password prompt. * * OTHER mode handles PAM_PROMPT_ECHO_OFF with read_passphrase() * and outputs messages to stderr. This mode is used if pam_chauthtok() * is called to update expired passwords. */ static int do_pam_conversation(int num_msg, const struct pam_message **msg, struct pam_response **resp, void *appdata_ptr) { struct pam_response *reply; int count; char buf[1024]; /* PAM will free this later */ reply = xmalloc(num_msg * sizeof(*reply)); for (count = 0; count < num_msg; count++) { if (pamstate == INITIAL_LOGIN) { /* * We can't use stdio yet, queue messages for * printing later */ switch(PAM_MSG_MEMBER(msg, count, msg_style)) { case PAM_PROMPT_ECHO_ON: xfree(reply); return PAM_CONV_ERR; case PAM_PROMPT_ECHO_OFF: if (__pampasswd == NULL) { xfree(reply); return PAM_CONV_ERR; } reply[count].resp = xstrdup(__pampasswd); reply[count].resp_retcode = PAM_SUCCESS; break; case PAM_ERROR_MSG: case PAM_TEXT_INFO: if (PAM_MSG_MEMBER(msg, count, msg) != NULL) { message_cat(&__pam_msg, PAM_MSG_MEMBER(msg, count, msg)); } reply[count].resp = xstrdup(""); reply[count].resp_retcode = PAM_SUCCESS; break; default: xfree(reply); return PAM_CONV_ERR; } } else { /* * stdio is connected, so interact directly */ switch(PAM_MSG_MEMBER(msg, count, msg_style)) { case PAM_PROMPT_ECHO_ON: fputs(PAM_MSG_MEMBER(msg, count, msg), stderr); fgets(buf, sizeof(buf), stdin); reply[count].resp = xstrdup(buf); reply[count].resp_retcode = PAM_SUCCESS; break; case PAM_PROMPT_ECHO_OFF: reply[count].resp = read_passphrase(PAM_MSG_MEMBER(msg, count, msg), RP_ALLOW_STDIN); reply[count].resp_retcode = PAM_SUCCESS; break; case PAM_ERROR_MSG: case PAM_TEXT_INFO: if (PAM_MSG_MEMBER(msg, count, msg) != NULL) fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, count, msg)); reply[count].resp = xstrdup(""); reply[count].resp_retcode = PAM_SUCCESS; break; default: xfree(reply); return PAM_CONV_ERR; } } } *resp = reply; return PAM_SUCCESS; } /* Called at exit to cleanly shutdown PAM */ void do_pam_cleanup_proc(void *context) { int pam_retval = PAM_SUCCESS; if (__pamh && session_opened) { pam_retval = pam_close_session(__pamh, 0); if (pam_retval != PAM_SUCCESS) log("Cannot close PAM session[%d]: %.200s", pam_retval, PAM_STRERROR(__pamh, pam_retval)); } if (__pamh && creds_set) { pam_retval = pam_setcred(__pamh, PAM_DELETE_CRED); if (pam_retval != PAM_SUCCESS) debug("Cannot delete credentials[%d]: %.200s", pam_retval, PAM_STRERROR(__pamh, pam_retval)); } if (__pamh) { pam_retval = pam_end(__pamh, pam_retval); if (pam_retval != PAM_SUCCESS) log("Cannot release PAM authentication[%d]: %.200s", pam_retval, PAM_STRERROR(__pamh, pam_retval)); } } /* Attempt password authentication using PAM */ int auth_pam_password(Authctxt *authctxt, const char *password) { extern ServerOptions options; int pam_retval; struct passwd *pw = authctxt->pw; do_pam_set_conv(&conv); __pampasswd = password; pamstate = INITIAL_LOGIN; pam_retval = do_pam_authenticate( options.permit_empty_passwd == 0 ? PAM_DISALLOW_NULL_AUTHTOK : 0); if (pam_retval == PAM_SUCCESS && pw) { debug("PAM password authentication accepted for " "%.100s", pw->pw_name); return 1; } else { debug("PAM password authentication failed for " "%.100s: %s", pw ? pw->pw_name : "an illegal user", PAM_STRERROR(__pamh, pam_retval)); return 0; } } /* Do account management using PAM */ int do_pam_account(char *username, char *remote_user) { int pam_retval; do_pam_set_conv(&conv); if (remote_user) { debug("PAM setting ruser to \"%.200s\"", remote_user); pam_retval = pam_set_item(__pamh, PAM_RUSER, remote_user); if (pam_retval != PAM_SUCCESS) fatal("PAM set ruser failed[%d]: %.200s", pam_retval, PAM_STRERROR(__pamh, pam_retval)); } pam_retval = pam_acct_mgmt(__pamh, 0); debug2("pam_acct_mgmt() = %d", pam_retval); switch (pam_retval) { case PAM_SUCCESS: /* This is what we want */ break; #if 0 case PAM_NEW_AUTHTOK_REQD: message_cat(&__pam_msg, use_privsep ? NEW_AUTHTOK_MSG_PRIVSEP : NEW_AUTHTOK_MSG); /* flag that password change is necessary */ password_change_required = 1; /* disallow other functionality for now */ no_port_forwarding_flag |= 2; no_agent_forwarding_flag |= 2; no_x11_forwarding_flag |= 2; break; #endif default: log("PAM rejected by account configuration[%d]: " "%.200s", pam_retval, PAM_STRERROR(__pamh, pam_retval)); return(0); } return(1); } /* Do PAM-specific session initialisation */ void do_pam_session(char *username, const char *ttyname) { int pam_retval; do_pam_set_conv(&conv); if (ttyname != NULL) { debug("PAM setting tty to \"%.200s\"", ttyname); pam_retval = pam_set_item(__pamh, PAM_TTY, ttyname); if (pam_retval != PAM_SUCCESS) fatal("PAM set tty failed[%d]: %.200s", pam_retval, PAM_STRERROR(__pamh, pam_retval)); } pam_retval = pam_open_session(__pamh, 0); if (pam_retval != PAM_SUCCESS) fatal("PAM session setup failed[%d]: %.200s", pam_retval, PAM_STRERROR(__pamh, pam_retval)); session_opened = 1; } /* Set PAM credentials */ void do_pam_setcred(int init) { int pam_retval; if (__pamh == NULL) return; do_pam_set_conv(&conv); debug("PAM establishing creds"); pam_retval = pam_setcred(__pamh, init ? PAM_ESTABLISH_CRED : PAM_REINITIALIZE_CRED); if (pam_retval != PAM_SUCCESS) { if (was_authenticated) fatal("PAM setcred failed[%d]: %.200s", pam_retval, PAM_STRERROR(__pamh, pam_retval)); else debug("PAM setcred failed[%d]: %.200s", pam_retval, PAM_STRERROR(__pamh, pam_retval)); } else creds_set = 1; } /* accessor function for file scope static variable */ int is_pam_password_change_required(void) { return password_change_required; } /* * Have user change authentication token if pam_acct_mgmt() indicated * it was expired. This needs to be called after an interactive * session is established and the user's pty is connected to * stdin/stdout/stderr. */ void do_pam_chauthtok(void) { int pam_retval; do_pam_set_conv(&conv); if (password_change_required) { if (use_privsep) fatal("Password changing is currently unsupported" " with privilege separation"); pamstate = OTHER; pam_retval = pam_chauthtok(__pamh, PAM_CHANGE_EXPIRED_AUTHTOK); if (pam_retval != PAM_SUCCESS) fatal("PAM pam_chauthtok failed[%d]: %.200s", pam_retval, PAM_STRERROR(__pamh, pam_retval)); #if 0 /* XXX: This would need to be done in the parent process, * but there's currently no way to pass such request. */ no_port_forwarding_flag &= ~2; no_agent_forwarding_flag &= ~2; no_x11_forwarding_flag &= ~2; if (!no_port_forwarding_flag && options.allow_tcp_forwarding) channel_permit_all_opens(); #endif } } /* Cleanly shutdown PAM */ void finish_pam(void) { do_pam_cleanup_proc(NULL); fatal_remove_cleanup(&do_pam_cleanup_proc, NULL); } /* Start PAM authentication for specified account */ void start_pam(const char *user) { int pam_retval; extern ServerOptions options; extern u_int utmp_len; const char *rhost; debug("Starting up PAM with username \"%.200s\"", user); pam_retval = pam_start(SSHD_PAM_SERVICE, user, &conv, &__pamh); if (pam_retval != PAM_SUCCESS) fatal("PAM initialisation failed[%d]: %.200s", pam_retval, PAM_STRERROR(__pamh, pam_retval)); rhost = get_remote_name_or_ip(utmp_len, options.verify_reverse_mapping); debug("PAM setting rhost to \"%.200s\"", rhost); pam_retval = pam_set_item(__pamh, PAM_RHOST, rhost); if (pam_retval != PAM_SUCCESS) fatal("PAM set rhost failed[%d]: %.200s", pam_retval, PAM_STRERROR(__pamh, pam_retval)); #ifdef PAM_TTY_KLUDGE /* * Some PAM modules (e.g. pam_time) require a TTY to operate, * and will fail in various stupid ways if they don't get one. * sshd doesn't set the tty until too late in the auth process and may * not even need one (for tty-less connections) * Kludge: Set a fake PAM_TTY */ pam_retval = pam_set_item(__pamh, PAM_TTY, "NODEVssh"); if (pam_retval != PAM_SUCCESS) fatal("PAM set tty failed[%d]: %.200s", pam_retval, PAM_STRERROR(__pamh, pam_retval)); #endif /* PAM_TTY_KLUDGE */ fatal_add_cleanup(&do_pam_cleanup_proc, NULL); } /* Return list of PAM environment strings */ char **fetch_pam_environment(void) { #ifdef HAVE_PAM_GETENVLIST return(pam_getenvlist(__pamh)); #else /* HAVE_PAM_GETENVLIST */ return(NULL); #endif /* HAVE_PAM_GETENVLIST */ } void free_pam_environment(char **env) { int i; if (env != NULL) { for (i = 0; env[i] != NULL; i++) xfree(env[i]); } } /* Print any messages that have been generated during authentication */ /* or account checking to stderr */ void print_pam_messages(void) { if (__pam_msg != NULL) fputs(__pam_msg, stderr); } /* Append a message to buffer */ void message_cat(char **p, const char *a) { char *cp; size_t new_len; new_len = strlen(a); if (*p) { size_t len = strlen(*p); *p = xrealloc(*p, new_len + len + 2); cp = *p + len; } else *p = cp = xmalloc(new_len + 2); memcpy(cp, a, new_len); cp[new_len] = '\n'; cp[new_len + 1] = '\0'; } #endif /* USE_PAM */