X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/fd094f49b722b793285fc6364d2a1b92f4a09639..06617857197c00b4fdd0e1456bf25c82c796f4cf:/auth-pam.c diff --git a/auth-pam.c b/auth-pam.c index 17e8d882..4b4c2f9d 100644 --- a/auth-pam.c +++ b/auth-pam.c @@ -1,9 +1,25 @@ /* - * Author: Damien Miller - * Copyright (c) 1999 Damien Miller - * All rights reserved - * Created: Thursday December 30 1999 - * PAM authentication and session management code. + * 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" @@ -11,77 +27,143 @@ #ifdef USE_PAM #include "ssh.h" #include "xmalloc.h" +#include "log.h" +#include "auth.h" +#include "auth-pam.h" #include "servconf.h" +#include "canohost.h" +#include "readpass.h" + +extern char *__progname; RCSID("$Id$"); -/* Callbacks */ -static int pamconv(int num_msg, const struct pam_message **msg, - struct pam_response **resp, void *appdata_ptr); -void pam_cleanup_proc(void *context); +#define NEW_AUTHTOK_MSG \ + "Warning: Your password has expired, please change it now" + +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 = { - pamconv, + do_pam_conversation, NULL }; -static struct pam_handle_t *pamh = NULL; -static const char *pampasswd = NULL; -static char *pamconv_msg = 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_NEWAUTHTOK_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); +} -/* PAM conversation function. This is really a kludge to get the password */ -/* into PAM and to pick up any messages generated by PAM into pamconv_msg */ -static int pamconv(int num_msg, const struct pam_message **msg, +/* 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; - size_t msg_len; - char *p; + char buf[1024]; /* PAM will free this later */ reply = malloc(num_msg * sizeof(*reply)); if (reply == NULL) - return PAM_CONV_ERR; - - for(count = 0; count < num_msg; count++) { - switch (msg[count]->msg_style) { + return PAM_CONV_ERR; + + 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: + free(reply); + return PAM_CONV_ERR; case PAM_PROMPT_ECHO_OFF: - if (pampasswd == NULL) { + if (__pampasswd == NULL) { free(reply); return PAM_CONV_ERR; } + reply[count].resp = xstrdup(__pampasswd); reply[count].resp_retcode = PAM_SUCCESS; - reply[count].resp = xstrdup(pampasswd); break; - + case PAM_ERROR_MSG: case PAM_TEXT_INFO: - reply[count].resp_retcode = PAM_SUCCESS; - reply[count].resp = xstrdup(""); - - if (msg[count]->msg == NULL) - break; - - debug("Adding PAM message: %s", msg[count]->msg); - - msg_len = strlen(msg[count]->msg); - if (pamconv_msg) { - size_t n = strlen(pamconv_msg); - pamconv_msg = xrealloc(pamconv_msg, n + msg_len + 2); - p = pamconv_msg + n; - } else { - pamconv_msg = p = xmalloc(msg_len + 2); + if ((*msg)[count].msg != NULL) { + message_cat(&__pam_msg, + PAM_MSG_MEMBER(msg, count, msg)); } - memcpy(p, msg[count]->msg, msg_len); - p[msg_len] = '\n'; - p[msg_len + 1] = '\0'; + reply[count].resp = xstrdup(""); + reply[count].resp_retcode = PAM_SUCCESS; break; - + default: + free(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 ((*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: free(reply); return PAM_CONV_ERR; + } } } @@ -91,55 +173,62 @@ static int pamconv(int num_msg, const struct pam_message **msg, } /* Called at exit to cleanly shutdown PAM */ -void pam_cleanup_proc(void *context) +void do_pam_cleanup_proc(void *context) { - int pam_retval; + int pam_retval = PAM_SUCCESS; - if (pamh != NULL) - { - pam_retval = pam_close_session((pam_handle_t *)pamh, 0); - if (pam_retval != PAM_SUCCESS) { - log("Cannot close PAM session: %.200s", - PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); - } + 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)); + } - pam_retval = pam_setcred((pam_handle_t *)pamh, PAM_DELETE_CRED); - if (pam_retval != PAM_SUCCESS) { - log("Cannot delete credentials: %.200s", - PAM_STRERROR((pam_handle_t *)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)); + } - pam_retval = pam_end((pam_handle_t *)pamh, pam_retval); - if (pam_retval != PAM_SUCCESS) { - log("Cannot release PAM authentication: %.200s", - PAM_STRERROR((pam_handle_t *)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 authentation using PAM */ -int auth_pam_password(struct passwd *pw, const char *password) +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); /* deny if no user. */ if (pw == NULL) return 0; - if (pw->pw_uid == 0 && options.permit_root_login == 2) + if (pw->pw_uid == 0 && options.permit_root_login == PERMIT_NO_PASSWD) return 0; if (*password == '\0' && options.permit_empty_passwd == 0) return 0; - pampasswd = password; - - pam_retval = pam_authenticate((pam_handle_t *)pamh, 0); + __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) { - debug("PAM Password authentication accepted for user \"%.100s\"", pw->pw_name); + debug("PAM Password authentication accepted for " + "user \"%.100s\"", pw->pw_name); return 1; } else { - debug("PAM Password authentication for \"%.100s\" failed: %s", - pw->pw_name, PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); + debug("PAM Password authentication for \"%.100s\" " + "failed[%d]: %s", pw->pw_name, pam_retval, + PAM_STRERROR(__pamh, pam_retval)); return 0; } } @@ -149,27 +238,36 @@ int do_pam_account(char *username, char *remote_user) { int pam_retval; - debug("PAM setting rhost to \"%.200s\"", get_canonical_hostname()); - pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_RHOST, - get_canonical_hostname()); - if (pam_retval != PAM_SUCCESS) { - fatal("PAM set rhost failed: %.200s", PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); - } + do_pam_set_conv(&conv); - if (remote_user != NULL) { + if (remote_user) { debug("PAM setting ruser to \"%.200s\"", remote_user); - pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_RUSER, remote_user); - if (pam_retval != PAM_SUCCESS) { - fatal("PAM set ruser failed: %.200s", PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); - } + 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((pam_handle_t *)pamh, 0); - if (pam_retval != PAM_SUCCESS) { - log("PAM rejected by account configuration: %.200s", PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); - return(0); + 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, NEW_AUTHTOK_MSG); + /* flag that password change is necessary */ + password_change_required = 1; + break; +#endif + default: + log("PAM rejected by account configuration[%d]: " + "%.200s", pam_retval, PAM_STRERROR(__pamh, + pam_retval)); + return(0); } - + return(1); } @@ -178,62 +276,159 @@ 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((pam_handle_t *)pamh, PAM_TTY, ttyname); + pam_retval = pam_set_item(__pamh, PAM_TTY, ttyname); if (pam_retval != PAM_SUCCESS) - fatal("PAM set tty failed: %.200s", PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); + fatal("PAM set tty failed[%d]: %.200s", + pam_retval, PAM_STRERROR(__pamh, pam_retval)); } - pam_retval = pam_open_session((pam_handle_t *)pamh, 0); + pam_retval = pam_open_session(__pamh, 0); if (pam_retval != PAM_SUCCESS) - fatal("PAM session setup failed: %.200s", PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); + fatal("PAM session setup failed[%d]: %.200s", + pam_retval, PAM_STRERROR(__pamh, pam_retval)); + + session_opened = 1; } -/* Set PAM credentials */ -void do_pam_setcred() +/* 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((pam_handle_t *)pamh, PAM_ESTABLISH_CRED); - if (pam_retval != PAM_SUCCESS) - fatal("PAM setcred failed: %.200s", PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); + 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/stout/stderr. + */ +void do_pam_chauthtok(void) +{ + int pam_retval; + + do_pam_set_conv(&conv); + + if (password_change_required) { + 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)); + } } /* Cleanly shutdown PAM */ void finish_pam(void) { - pam_cleanup_proc(NULL); - fatal_remove_cleanup(&pam_cleanup_proc, NULL); + do_pam_cleanup_proc(NULL); + fatal_remove_cleanup(&do_pam_cleanup_proc, NULL); } /* Start PAM authentication for specified account */ -void start_pam(struct passwd *pw) +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\"", pw->pw_name); + debug("Starting up PAM with username \"%.200s\"", user); + + pam_retval = pam_start(SSHD_PAM_SERVICE, user, &conv, &__pamh); - pam_retval = pam_start("sshd", pw->pw_name, &conv, (pam_handle_t**)&pamh); if (pam_retval != PAM_SUCCESS) - fatal("PAM initialisation failed: %.200s", PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); + 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); - fatal_add_cleanup(&pam_cleanup_proc, NULL); + 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 enviornment strings */ char **fetch_pam_environment(void) { - return(pam_getenvlist((pam_handle_t *)pamh)); +#ifdef HAVE_PAM_GETENVLIST + return(pam_getenvlist(__pamh)); +#else /* HAVE_PAM_GETENVLIST */ + return(NULL); +#endif /* HAVE_PAM_GETENVLIST */ } /* Print any messages that have been generated during authentication */ /* or account checking to stderr */ void print_pam_messages(void) { - if (pamconv_msg != NULL) - fprintf(stderr, pamconv_msg); + 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 */