/*- * Copyright (c) 2002 Networks Associates Technology, Inc. * All rights reserved. * * This software was developed for the FreeBSD Project by ThinkSec AS and * NAI Labs, the Security Research Division of Network Associates, Inc. * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the * DARPA CHATS research program. * * 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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. */ /* Based on $FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des Exp $ */ #include "includes.h" RCSID("$Id: auth-pam.c,v 1.72.2.1 2003/09/16 06:00:52 djm Exp $"); #ifdef USE_PAM #include #include "auth.h" #include "auth-pam.h" #include "buffer.h" #include "bufaux.h" #include "canohost.h" #include "log.h" #include "monitor_wrap.h" #include "msg.h" #include "packet.h" #include "readpass.h" #include "servconf.h" #include "ssh2.h" #include "xmalloc.h" #include "auth-options.h" extern ServerOptions options; #define __unused #ifdef USE_POSIX_THREADS #include /* * Avoid namespace clash when *not* using pthreads for systems *with* * pthreads, which unconditionally define pthread_t via sys/types.h * (e.g. Linux) */ typedef pthread_t sp_pthread_t; #else /* * Simulate threads with processes. */ typedef pid_t sp_pthread_t; static void pthread_exit(void *value __unused) { _exit(0); } static int pthread_create(sp_pthread_t *thread, const void *attr __unused, void *(*thread_start)(void *), void *arg) { pid_t pid; switch ((pid = fork())) { case -1: error("fork(): %s", strerror(errno)); return (-1); case 0: thread_start(arg); _exit(1); default: *thread = pid; return (0); } } static int pthread_cancel(sp_pthread_t thread) { return (kill(thread, SIGTERM)); } static int pthread_join(sp_pthread_t thread, void **value __unused) { int status; waitpid(thread, &status, 0); return (status); } #endif static pam_handle_t *sshpam_handle; static int sshpam_err; static int sshpam_authenticated; static int sshpam_new_authtok_reqd; static int sshpam_session_open; static int sshpam_cred_established; struct pam_ctxt { sp_pthread_t pam_thread; int pam_psock; int pam_csock; int pam_done; }; static void sshpam_free_ctx(void *); /* * Conversation function for authentication thread. */ static int sshpam_thread_conv(int n, const struct pam_message **msg, struct pam_response **resp, void *data) { Buffer buffer; struct pam_ctxt *ctxt; int i; ctxt = data; if (n <= 0 || n > PAM_MAX_NUM_MSG) return (PAM_CONV_ERR); *resp = xmalloc(n * sizeof **resp); buffer_init(&buffer); for (i = 0; i < n; ++i) { resp[i]->resp_retcode = 0; resp[i]->resp = NULL; switch (PAM_MSG_MEMBER(msg, i, msg_style)) { case PAM_PROMPT_ECHO_OFF: buffer_put_cstring(&buffer, PAM_MSG_MEMBER(msg, i, msg)); ssh_msg_send(ctxt->pam_csock, PAM_MSG_MEMBER(msg, i, msg_style), &buffer); ssh_msg_recv(ctxt->pam_csock, &buffer); if (buffer_get_char(&buffer) != PAM_AUTHTOK) goto fail; resp[i]->resp = buffer_get_string(&buffer, NULL); break; case PAM_PROMPT_ECHO_ON: buffer_put_cstring(&buffer, PAM_MSG_MEMBER(msg, i, msg)); ssh_msg_send(ctxt->pam_csock, PAM_MSG_MEMBER(msg, i, msg_style), &buffer); ssh_msg_recv(ctxt->pam_csock, &buffer); if (buffer_get_char(&buffer) != PAM_AUTHTOK) goto fail; resp[i]->resp = buffer_get_string(&buffer, NULL); break; case PAM_ERROR_MSG: buffer_put_cstring(&buffer, PAM_MSG_MEMBER(msg, i, msg)); ssh_msg_send(ctxt->pam_csock, PAM_MSG_MEMBER(msg, i, msg_style), &buffer); break; case PAM_TEXT_INFO: buffer_put_cstring(&buffer, PAM_MSG_MEMBER(msg, i, msg)); ssh_msg_send(ctxt->pam_csock, PAM_MSG_MEMBER(msg, i, msg_style), &buffer); break; default: goto fail; } buffer_clear(&buffer); } buffer_free(&buffer); return (PAM_SUCCESS); fail: while (i) xfree(resp[--i]); xfree(*resp); *resp = NULL; buffer_free(&buffer); return (PAM_CONV_ERR); } /* * Authentication thread. */ static void * sshpam_thread(void *ctxtp) { struct pam_ctxt *ctxt = ctxtp; Buffer buffer; struct pam_conv sshpam_conv; #ifndef USE_POSIX_THREADS const char *pam_user; pam_get_item(sshpam_handle, PAM_USER, (const void **)&pam_user); setproctitle("%s [pam]", pam_user); #endif sshpam_conv.conv = sshpam_thread_conv; sshpam_conv.appdata_ptr = ctxt; buffer_init(&buffer); sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, (const void *)&sshpam_conv); if (sshpam_err != PAM_SUCCESS) goto auth_fail; sshpam_err = pam_authenticate(sshpam_handle, 0); if (sshpam_err != PAM_SUCCESS) goto auth_fail; buffer_put_cstring(&buffer, "OK"); ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer); buffer_free(&buffer); pthread_exit(NULL); auth_fail: buffer_put_cstring(&buffer, pam_strerror(sshpam_handle, sshpam_err)); ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer); buffer_free(&buffer); pthread_exit(NULL); return (NULL); /* Avoid warning for non-pthread case */ } static void sshpam_thread_cleanup(void *ctxtp) { struct pam_ctxt *ctxt = ctxtp; pthread_cancel(ctxt->pam_thread); pthread_join(ctxt->pam_thread, NULL); close(ctxt->pam_psock); close(ctxt->pam_csock); } static int sshpam_null_conv(int n, const struct pam_message **msg, struct pam_response **resp, void *data) { return (PAM_CONV_ERR); } static struct pam_conv null_conv = { sshpam_null_conv, NULL }; static void sshpam_cleanup(void *arg) { (void)arg; debug("PAM: cleanup"); pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); if (sshpam_cred_established) { pam_setcred(sshpam_handle, PAM_DELETE_CRED); sshpam_cred_established = 0; } if (sshpam_session_open) { pam_close_session(sshpam_handle, PAM_SILENT); sshpam_session_open = 0; } sshpam_authenticated = sshpam_new_authtok_reqd = 0; pam_end(sshpam_handle, sshpam_err); sshpam_handle = NULL; } static int sshpam_init(const char *user) { extern u_int utmp_len; extern char *__progname; const char *pam_rhost, *pam_user; if (sshpam_handle != NULL) { /* We already have a PAM context; check if the user matches */ sshpam_err = pam_get_item(sshpam_handle, PAM_USER, (const void **)&pam_user); if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) return (0); fatal_remove_cleanup(sshpam_cleanup, NULL); pam_end(sshpam_handle, sshpam_err); sshpam_handle = NULL; } debug("PAM: initializing for \"%s\"", user); sshpam_err = pam_start(SSHD_PAM_SERVICE, user, &null_conv, &sshpam_handle); if (sshpam_err != PAM_SUCCESS) { pam_end(sshpam_handle, sshpam_err); sshpam_handle = NULL; return (-1); } pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns); debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost); sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost); if (sshpam_err != PAM_SUCCESS) { pam_end(sshpam_handle, sshpam_err); sshpam_handle = NULL; return (-1); } #ifdef PAM_TTY_KLUDGE /* * Some silly PAM modules (e.g. pam_time) require a TTY to operate. * sshd doesn't set the tty until too late in the auth process and * may not even set one (for tty-less connections) */ debug("PAM: setting PAM_TTY to \"ssh\""); sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); if (sshpam_err != PAM_SUCCESS) { pam_end(sshpam_handle, sshpam_err); sshpam_handle = NULL; return (-1); } #endif fatal_add_cleanup(sshpam_cleanup, NULL); return (0); } static void * sshpam_init_ctx(Authctxt *authctxt) { struct pam_ctxt *ctxt; int socks[2]; /* Refuse to start if we don't have PAM enabled */ if (!options.use_pam) return NULL; /* Initialize PAM */ if (sshpam_init(authctxt->user) == -1) { error("PAM: initialization failed"); return (NULL); } ctxt = xmalloc(sizeof *ctxt); ctxt->pam_done = 0; /* Start the authentication thread */ if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { error("PAM: failed create sockets: %s", strerror(errno)); xfree(ctxt); return (NULL); } ctxt->pam_psock = socks[0]; ctxt->pam_csock = socks[1]; if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) { error("PAM: failed to start authentication thread: %s", strerror(errno)); close(socks[0]); close(socks[1]); xfree(ctxt); return (NULL); } fatal_add_cleanup(sshpam_thread_cleanup, ctxt); return (ctxt); } static int sshpam_query(void *ctx, char **name, char **info, u_int *num, char ***prompts, u_int **echo_on) { Buffer buffer; struct pam_ctxt *ctxt = ctx; size_t plen; u_char type; char *msg; size_t len; buffer_init(&buffer); *name = xstrdup(""); *info = xstrdup(""); *prompts = xmalloc(sizeof(char *)); **prompts = NULL; plen = 0; *echo_on = xmalloc(sizeof(u_int)); while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) { type = buffer_get_char(&buffer); msg = buffer_get_string(&buffer, NULL); switch (type) { case PAM_PROMPT_ECHO_ON: case PAM_PROMPT_ECHO_OFF: *num = 1; len = plen + strlen(msg) + 1; **prompts = xrealloc(**prompts, len); plen += snprintf(**prompts + plen, len, "%s", msg); **echo_on = (type == PAM_PROMPT_ECHO_ON); xfree(msg); return (0); case PAM_ERROR_MSG: case PAM_TEXT_INFO: /* accumulate messages */ len = plen + strlen(msg) + 1; **prompts = xrealloc(**prompts, len); plen += snprintf(**prompts + plen, len, "%s", msg); xfree(msg); break; case PAM_SUCCESS: case PAM_AUTH_ERR: if (**prompts != NULL) { /* drain any accumulated messages */ #if 0 /* XXX - not compatible with privsep */ packet_start(SSH2_MSG_USERAUTH_BANNER); packet_put_cstring(**prompts); packet_put_cstring(""); packet_send(); packet_write_wait(); #endif xfree(**prompts); **prompts = NULL; } if (type == PAM_SUCCESS) { *num = 0; **echo_on = 0; ctxt->pam_done = 1; xfree(msg); return (0); } error("PAM: %s", msg); default: *num = 0; **echo_on = 0; xfree(msg); ctxt->pam_done = -1; return (-1); } } return (-1); } /* XXX - see also comment in auth-chall.c:verify_response */ static int sshpam_respond(void *ctx, u_int num, char **resp) { Buffer buffer; struct pam_ctxt *ctxt = ctx; debug2("PAM: %s", __func__); switch (ctxt->pam_done) { case 1: sshpam_authenticated = 1; return (0); case 0: break; default: return (-1); } if (num != 1) { error("PAM: expected one response, got %u", num); return (-1); } buffer_init(&buffer); buffer_put_cstring(&buffer, *resp); ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer); buffer_free(&buffer); return (1); } static void sshpam_free_ctx(void *ctxtp) { struct pam_ctxt *ctxt = ctxtp; fatal_remove_cleanup(sshpam_thread_cleanup, ctxt); sshpam_thread_cleanup(ctxtp); xfree(ctxt); /* * We don't call sshpam_cleanup() here because we may need the PAM * handle at a later stage, e.g. when setting up a session. It's * still on the cleanup list, so pam_end() *will* be called before * the server process terminates. */ } KbdintDevice sshpam_device = { "pam", sshpam_init_ctx, sshpam_query, sshpam_respond, sshpam_free_ctx }; KbdintDevice mm_sshpam_device = { "pam", mm_sshpam_init_ctx, mm_sshpam_query, mm_sshpam_respond, mm_sshpam_free_ctx }; /* * This replaces auth-pam.c */ void start_pam(const char *user) { if (!options.use_pam) fatal("PAM: initialisation requested when UsePAM=no"); if (sshpam_init(user) == -1) fatal("PAM: initialisation failed"); } void finish_pam(void) { fatal_remove_cleanup(sshpam_cleanup, NULL); sshpam_cleanup(NULL); } u_int do_pam_account(void) { sshpam_err = pam_acct_mgmt(sshpam_handle, 0); debug3("%s: pam_acct_mgmt = %d", __func__, sshpam_err); if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) return (0); if (sshpam_err == PAM_NEW_AUTHTOK_REQD) { sshpam_new_authtok_reqd = 1; /* Prevent forwardings until password changed */ no_port_forwarding_flag |= 2; no_agent_forwarding_flag |= 2; no_x11_forwarding_flag |= 2; } return (1); } void do_pam_session(void) { sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); if (sshpam_err != PAM_SUCCESS) fatal("PAM: failed to set PAM_CONV: %s", pam_strerror(sshpam_handle, sshpam_err)); sshpam_err = pam_open_session(sshpam_handle, 0); if (sshpam_err != PAM_SUCCESS) fatal("PAM: pam_open_session(): %s", pam_strerror(sshpam_handle, sshpam_err)); sshpam_session_open = 1; } void do_pam_set_tty(const char *tty) { if (tty != NULL) { debug("PAM: setting PAM_TTY to \"%s\"", tty); sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty); if (sshpam_err != PAM_SUCCESS) fatal("PAM: failed to set PAM_TTY: %s", pam_strerror(sshpam_handle, sshpam_err)); } } void do_pam_setcred(int init) { sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); if (sshpam_err != PAM_SUCCESS) fatal("PAM: failed to set PAM_CONV: %s", pam_strerror(sshpam_handle, sshpam_err)); if (init) { debug("PAM: establishing credentials"); sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); } else { debug("PAM: reinitializing credentials"); sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); } if (sshpam_err == PAM_SUCCESS) { sshpam_cred_established = 1; return; } if (sshpam_authenticated) fatal("PAM: pam_setcred(): %s", pam_strerror(sshpam_handle, sshpam_err)); else debug("PAM: pam_setcred(): %s", pam_strerror(sshpam_handle, sshpam_err)); } int is_pam_password_change_required(void) { return (sshpam_new_authtok_reqd); } static int pam_chauthtok_conv(int n, const struct pam_message **msg, struct pam_response **resp, void *data) { char input[PAM_MAX_MSG_SIZE]; int i; if (n <= 0 || n > PAM_MAX_NUM_MSG) return (PAM_CONV_ERR); *resp = xmalloc(n * sizeof **resp); for (i = 0; i < n; ++i) { switch (PAM_MSG_MEMBER(msg, i, msg_style)) { case PAM_PROMPT_ECHO_OFF: resp[i]->resp = read_passphrase(PAM_MSG_MEMBER(msg, i, msg), RP_ALLOW_STDIN); resp[i]->resp_retcode = PAM_SUCCESS; break; case PAM_PROMPT_ECHO_ON: fputs(PAM_MSG_MEMBER(msg, i, msg), stderr); fgets(input, sizeof input, stdin); resp[i]->resp = xstrdup(input); resp[i]->resp_retcode = PAM_SUCCESS; break; case PAM_ERROR_MSG: case PAM_TEXT_INFO: fputs(PAM_MSG_MEMBER(msg, i, msg), stderr); resp[i]->resp_retcode = PAM_SUCCESS; break; default: goto fail; } } return (PAM_SUCCESS); fail: while (i) xfree(resp[--i]); xfree(*resp); *resp = NULL; return (PAM_CONV_ERR); } /* * XXX this should be done in the authentication phase, but ssh1 doesn't * support that */ void do_pam_chauthtok(void) { struct pam_conv pam_conv; pam_conv.conv = pam_chauthtok_conv; pam_conv.appdata_ptr = NULL; if (use_privsep) fatal("Password expired (unable to change with privsep)"); sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, (const void *)&pam_conv); if (sshpam_err != PAM_SUCCESS) fatal("PAM: failed to set PAM_CONV: %s", pam_strerror(sshpam_handle, sshpam_err)); debug("PAM: changing password"); sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); if (sshpam_err != PAM_SUCCESS) fatal("PAM: pam_chauthtok(): %s", pam_strerror(sshpam_handle, sshpam_err)); } /* * Set a PAM environment string. We need to do this so that the session * modules can handle things like Kerberos/GSI credentials that appear * during the ssh authentication process. */ int do_pam_putenv(char *name, char *value) { int ret = 1; #ifdef HAVE_PAM_PUTENV char *compound; size_t len; len = strlen(name) + strlen(value) + 2; compound = xmalloc(len); snprintf(compound, len, "%s=%s", name, value); ret = pam_putenv(sshpam_handle, compound); xfree(compound); #endif return (ret); } void print_pam_messages(void) { /* XXX */ } char ** fetch_pam_environment(void) { #ifdef HAVE_PAM_GETENVLIST debug("PAM: retrieving environment"); return (pam_getenvlist(sshpam_handle)); #else return (NULL); #endif } void free_pam_environment(char **env) { char **envp; if (env == NULL) return; for (envp = env; *envp; envp++) xfree(*envp); xfree(env); } #endif /* USE_PAM */