X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/013eab17f87539f6ae8b69338bd6e00fe52aa33f..HEAD:/auth2.c diff --git a/auth2.c b/auth2.c index ffd70328..5d546855 100644 --- a/auth2.c +++ b/auth2.c @@ -1,3 +1,4 @@ +/* $OpenBSD: auth2.c,v 1.121 2009/06/22 05:39:28 dtucker Exp $ */ /* * Copyright (c) 2000 Markus Friedl. All rights reserved. * @@ -23,32 +24,70 @@ */ #include "includes.h" -RCSID("$OpenBSD: auth2.c,v 1.92 2002/05/25 18:51:07 markus Exp $"); -#include "ssh2.h" +#include +#include +#include + +#include +#include +#include +#include +#include + +#include "atomicio.h" #include "xmalloc.h" +#include "ssh2.h" #include "packet.h" #include "log.h" +#include "buffer.h" #include "servconf.h" #include "compat.h" +#include "key.h" +#include "hostfile.h" #include "auth.h" #include "dispatch.h" #include "pathnames.h" +#include "buffer.h" + +#ifdef GSSAPI +#include "ssh-gss.h" +#endif #include "monitor_wrap.h" /* import */ extern ServerOptions options; extern u_char *session_id2; -extern int session_id2_len; - -Authctxt *x_authctxt = NULL; -static int one = 1; +extern u_int session_id2_len; +extern Buffer loginmsg; + +/* methods */ + +extern Authmethod method_none; +extern Authmethod method_pubkey; +extern Authmethod method_passwd; +extern Authmethod method_kbdint; +extern Authmethod method_hostbased; +#ifdef GSSAPI +extern Authmethod method_gssapi; +#endif +#ifdef JPAKE +extern Authmethod method_jpake; +#endif -typedef struct Authmethod Authmethod; -struct Authmethod { - char *name; - int (*userauth)(Authctxt *authctxt); - int *enabled; +Authmethod *authmethods[] = { + &method_none, + &method_pubkey, +#ifdef GSSAPI + &method_gssapi, +#endif +#ifdef JPAKE + &method_jpake, +#endif + &method_passwd, + &method_kbdint, + &method_hostbased, + NULL }; /* protocol */ @@ -59,62 +98,90 @@ static void input_userauth_request(int, u_int32_t, void *); /* helper */ static Authmethod *authmethod_lookup(const char *); static char *authmethods_get(void); -int user_key_allowed(struct passwd *, Key *); -int hostbased_key_allowed(struct passwd *, const char *, char *, Key *); - -/* auth */ - -Authmethod authmethods[] = { - {"none", - userauth_none, - &one}, - {"publickey", - userauth_pubkey, - &options.pubkey_authentication}, - {"password", - userauth_passwd, - &options.password_authentication}, - {"keyboard-interactive", - userauth_kbdint, - &options.kbd_interactive_authentication}, - {"hostbased", - userauth_hostbased, - &options.hostbased_authentication}, - {NULL, NULL, NULL} -}; -/* - * loop until authctxt->success == TRUE - */ +char * +auth2_read_banner(void) +{ + struct stat st; + char *banner = NULL; + size_t len, n; + int fd; -Authctxt * -do_authentication2(void) + if ((fd = open(options.banner, O_RDONLY)) == -1) + return (NULL); + if (fstat(fd, &st) == -1) { + close(fd); + return (NULL); + } + if (st.st_size > 1*1024*1024) { + close(fd); + return (NULL); + } + + len = (size_t)st.st_size; /* truncate */ + banner = xmalloc(len + 1); + n = atomicio(read, fd, banner, len); + close(fd); + + if (n != len) { + xfree(banner); + return (NULL); + } + banner[n] = '\0'; + + return (banner); +} + +void +userauth_send_banner(const char *msg) { - Authctxt *authctxt = authctxt_new(); + if (datafellows & SSH_BUG_BANNER) + return; - x_authctxt = authctxt; /*XXX*/ + packet_start(SSH2_MSG_USERAUTH_BANNER); + packet_put_cstring(msg); + packet_put_cstring(""); /* language, unused */ + packet_send(); + debug("%s: sent", __func__); +} - /* challenge-response is implemented via keyboard interactive */ - if (options.challenge_response_authentication) - options.kbd_interactive_authentication = 1; - if (options.pam_authentication_via_kbd_int) - options.kbd_interactive_authentication = 1; - if (use_privsep) - options.pam_authentication_via_kbd_int = 0; +static void +userauth_banner(void) +{ + char *banner = NULL; + + if (options.banner == NULL || + strcasecmp(options.banner, "none") == 0 || + (datafellows & SSH_BUG_BANNER) != 0) + return; + if ((banner = PRIVSEP(auth2_read_banner())) == NULL) + goto done; + userauth_send_banner(banner); + +done: + if (banner) + xfree(banner); +} + +/* + * loop until authctxt->success == TRUE + */ +void +do_authentication2(Authctxt *authctxt) +{ dispatch_init(&dispatch_protocol_error); dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); - - return (authctxt); } +/*ARGSUSED*/ static void input_service_request(int type, u_int32_t seq, void *ctxt) { Authctxt *authctxt = ctxt; u_int len; - int accept = 0; + int acceptit = 0; char *service = packet_get_string(&len); packet_check_eom(); @@ -123,14 +190,14 @@ input_service_request(int type, u_int32_t seq, void *ctxt) if (strcmp(service, "ssh-userauth") == 0) { if (!authctxt->success) { - accept = 1; + acceptit = 1; /* now we can handle user-auth requests */ dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); } } /* XXX all other service requests are denied */ - if (accept) { + if (acceptit) { packet_start(SSH2_MSG_SERVICE_ACCEPT); packet_put_cstring(service); packet_send(); @@ -142,6 +209,7 @@ input_service_request(int type, u_int32_t seq, void *ctxt) xfree(service); } +/*ARGSUSED*/ static void input_userauth_request(int type, u_int32_t seq, void *ctxt) { @@ -165,25 +233,28 @@ input_userauth_request(int type, u_int32_t seq, void *ctxt) if (authctxt->attempt++ == 0) { /* setup auth context */ authctxt->pw = PRIVSEP(getpwnamallow(user)); + authctxt->user = xstrdup(user); if (authctxt->pw && strcmp(service, "ssh-connection")==0) { authctxt->valid = 1; debug2("input_userauth_request: setting up authctxt for %s", user); -#ifdef USE_PAM - PRIVSEP(start_pam(authctxt->pw->pw_name)); -#endif } else { - log("input_userauth_request: illegal user %s", user); -#ifdef USE_PAM - PRIVSEP(start_pam("NOUSER")); + logit("input_userauth_request: invalid user %s", user); + authctxt->pw = fakepw(); +#ifdef SSH_AUDIT_EVENTS + PRIVSEP(audit_event(SSH_INVALID_USER)); #endif } - setproctitle("%s%s", authctxt->pw ? user : "unknown", +#ifdef USE_PAM + if (options.use_pam) + PRIVSEP(start_pam(authctxt)); +#endif + setproctitle("%s%s", authctxt->valid ? user : "unknown", use_privsep ? " [net]" : ""); - authctxt->user = xstrdup(user); authctxt->service = xstrdup(service); authctxt->style = style ? xstrdup(style) : NULL; if (use_privsep) mm_inform_authserv(service, style); + userauth_banner(); } else if (strcmp(user, authctxt->user) != 0 || strcmp(service, authctxt->service) != 0) { packet_disconnect("Change of username or service not allowed: " @@ -192,11 +263,21 @@ input_userauth_request(int type, u_int32_t seq, void *ctxt) } /* reset state */ auth2_challenge_stop(authctxt); +#ifdef JPAKE + auth2_jpake_stop(authctxt); +#endif + +#ifdef GSSAPI + /* XXX move to auth2_gssapi_stop() */ + dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); + dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); +#endif + authctxt->postponed = 0; /* try to authenticate user */ m = authmethod_lookup(method); - if (m != NULL) { + if (m != NULL && authctxt->failures < options.max_authtries) { debug2("input_userauth_request: try method %s", method); authenticated = m->userauth(authctxt); } @@ -218,14 +299,34 @@ userauth_finish(Authctxt *authctxt, int authenticated, char *method) /* Special handling for root */ if (authenticated && authctxt->pw->pw_uid == 0 && - !auth_root_allowed(method)) + !auth_root_allowed(method)) { authenticated = 0; +#ifdef SSH_AUDIT_EVENTS + PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED)); +#endif + } #ifdef USE_PAM - if (!use_privsep && authenticated && authctxt->user && - !do_pam_account(authctxt->user, NULL)) + if (options.use_pam && authenticated) { + if (!PRIVSEP(do_pam_account())) { + /* if PAM returned a message, send it to the user */ + if (buffer_len(&loginmsg) > 0) { + buffer_append(&loginmsg, "\0", 1); + userauth_send_banner(buffer_ptr(&loginmsg)); + packet_write_wait(); + } + fatal("Access denied for user %s by PAM account " + "configuration", authctxt->user); + } + } +#endif + +#ifdef _UNICOS + if (authenticated && cray_access_denied(authctxt->user)) { authenticated = 0; -#endif /* USE_PAM */ + fatal("Access denied for user %s.",authctxt->user); + } +#endif /* _UNICOS */ /* Log before sending the reply */ auth_log(authctxt, authenticated, method, " ssh2"); @@ -243,12 +344,14 @@ userauth_finish(Authctxt *authctxt, int authenticated, char *method) /* now we can break out */ authctxt->success = 1; } else { - if (authctxt->failures++ > AUTH_FAIL_MAX) { -#ifdef WITH_AIXAUTHENTICATE - loginfailed(authctxt->user, - get_canonical_hostname(options.verify_reverse_mapping), - "ssh"); -#endif /* WITH_AIXAUTHENTICATE */ + + /* Allow initial try of "none" auth without failure penalty */ + if (authctxt->attempt > 1 || strcmp(method, "none") != 0) + authctxt->failures++; + if (authctxt->failures >= options.max_authtries) { +#ifdef SSH_AUDIT_EVENTS + PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES)); +#endif packet_disconnect(AUTH_FAIL_MSG, authctxt->user); } methods = authmethods_get(); @@ -261,352 +364,23 @@ userauth_finish(Authctxt *authctxt, int authenticated, char *method) } } -char * -auth2_read_banner(void) -{ - struct stat st; - char *banner = NULL; - off_t len, n; - int fd; - - if ((fd = open(options.banner, O_RDONLY)) == -1) - return (NULL); - if (fstat(fd, &st) == -1) { - close(fd); - return (NULL); - } - len = st.st_size; - banner = xmalloc(len + 1); - n = atomicio(read, fd, banner, len); - close(fd); - - if (n != len) { - free(banner); - return (NULL); - } - banner[n] = '\0'; - - return (banner); -} - -static void -userauth_banner(void) -{ - char *banner = NULL; - - if (options.banner == NULL || (datafellows & SSH_BUG_BANNER)) - return; - - if ((banner = PRIVSEP(auth2_read_banner())) == NULL) - goto done; - - packet_start(SSH2_MSG_USERAUTH_BANNER); - packet_put_cstring(banner); - packet_put_cstring(""); /* language, unused */ - packet_send(); - debug("userauth_banner: sent"); -done: - if (banner) - xfree(banner); - return; -} - -static int -userauth_none(Authctxt *authctxt) -{ - /* disable method "none", only allowed one time */ - Authmethod *m = authmethod_lookup("none"); - if (m != NULL) - m->enabled = NULL; - packet_check_eom(); - userauth_banner(); - - if (authctxt->valid == 0) - return(0); - -#ifdef HAVE_CYGWIN - if (check_nt_auth(1, authctxt->pw) == 0) - return(0); -#endif - return PRIVSEP(auth_password(authctxt, "")); -} - -static int -userauth_passwd(Authctxt *authctxt) -{ - char *password; - int authenticated = 0; - int change; - u_int len; - change = packet_get_char(); - if (change) - log("password change not supported"); - password = packet_get_string(&len); - packet_check_eom(); - if (authctxt->valid && -#ifdef HAVE_CYGWIN - check_nt_auth(1, authctxt->pw) && -#endif - PRIVSEP(auth_password(authctxt, password)) == 1) - authenticated = 1; - memset(password, 0, len); - xfree(password); - return authenticated; -} - -static int -userauth_kbdint(Authctxt *authctxt) -{ - int authenticated = 0; - char *lang, *devs; - - lang = packet_get_string(NULL); - devs = packet_get_string(NULL); - packet_check_eom(); - - debug("keyboard-interactive devs %s", devs); - - if (options.challenge_response_authentication) - authenticated = auth2_challenge(authctxt, devs); - -#ifdef USE_PAM - if (authenticated == 0 && options.pam_authentication_via_kbd_int) - authenticated = auth2_pam(authctxt); -#endif - xfree(devs); - xfree(lang); -#ifdef HAVE_CYGWIN - if (check_nt_auth(0, authctxt->pw) == 0) - return(0); -#endif - return authenticated; -} - -static int -userauth_pubkey(Authctxt *authctxt) -{ - Buffer b; - Key *key = NULL; - char *pkalg; - u_char *pkblob, *sig; - u_int alen, blen, slen; - int have_sig, pktype; - int authenticated = 0; - - if (!authctxt->valid) { - debug2("userauth_pubkey: disabled because of invalid user"); - return 0; - } - have_sig = packet_get_char(); - if (datafellows & SSH_BUG_PKAUTH) { - debug2("userauth_pubkey: SSH_BUG_PKAUTH"); - /* no explicit pkalg given */ - pkblob = packet_get_string(&blen); - buffer_init(&b); - buffer_append(&b, pkblob, blen); - /* so we have to extract the pkalg from the pkblob */ - pkalg = buffer_get_string(&b, &alen); - buffer_free(&b); - } else { - pkalg = packet_get_string(&alen); - pkblob = packet_get_string(&blen); - } - pktype = key_type_from_name(pkalg); - if (pktype == KEY_UNSPEC) { - /* this is perfectly legal */ - log("userauth_pubkey: unsupported public key algorithm: %s", - pkalg); - goto done; - } - key = key_from_blob(pkblob, blen); - if (key == NULL) { - error("userauth_pubkey: cannot decode key: %s", pkalg); - goto done; - } - if (key->type != pktype) { - error("userauth_pubkey: type mismatch for decoded key " - "(received %d, expected %d)", key->type, pktype); - goto done; - } - if (have_sig) { - sig = packet_get_string(&slen); - packet_check_eom(); - buffer_init(&b); - if (datafellows & SSH_OLD_SESSIONID) { - buffer_append(&b, session_id2, session_id2_len); - } else { - buffer_put_string(&b, session_id2, session_id2_len); - } - /* reconstruct packet */ - buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); - buffer_put_cstring(&b, authctxt->user); - buffer_put_cstring(&b, - datafellows & SSH_BUG_PKSERVICE ? - "ssh-userauth" : - authctxt->service); - if (datafellows & SSH_BUG_PKAUTH) { - buffer_put_char(&b, have_sig); - } else { - buffer_put_cstring(&b, "publickey"); - buffer_put_char(&b, have_sig); - buffer_put_cstring(&b, pkalg); - } - buffer_put_string(&b, pkblob, blen); -#ifdef DEBUG_PK - buffer_dump(&b); -#endif - /* test for correct signature */ - authenticated = 0; - if (PRIVSEP(user_key_allowed(authctxt->pw, key)) && - PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b), - buffer_len(&b))) == 1) - authenticated = 1; - buffer_clear(&b); - xfree(sig); - } else { - debug("test whether pkalg/pkblob are acceptable"); - packet_check_eom(); - - /* XXX fake reply and always send PK_OK ? */ - /* - * XXX this allows testing whether a user is allowed - * to login: if you happen to have a valid pubkey this - * message is sent. the message is NEVER sent at all - * if a user is not allowed to login. is this an - * issue? -markus - */ - if (PRIVSEP(user_key_allowed(authctxt->pw, key))) { - packet_start(SSH2_MSG_USERAUTH_PK_OK); - packet_put_string(pkalg, alen); - packet_put_string(pkblob, blen); - packet_send(); - packet_write_wait(); - authctxt->postponed = 1; - } - } - if (authenticated != 1) - auth_clear_options(); -done: - debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg); - if (key != NULL) - key_free(key); - xfree(pkalg); - xfree(pkblob); -#ifdef HAVE_CYGWIN - if (check_nt_auth(0, authctxt->pw) == 0) - return(0); -#endif - return authenticated; -} - -static int -userauth_hostbased(Authctxt *authctxt) -{ - Buffer b; - Key *key = NULL; - char *pkalg, *cuser, *chost, *service; - u_char *pkblob, *sig; - u_int alen, blen, slen; - int pktype; - int authenticated = 0; - - if (!authctxt->valid) { - debug2("userauth_hostbased: disabled because of invalid user"); - return 0; - } - pkalg = packet_get_string(&alen); - pkblob = packet_get_string(&blen); - chost = packet_get_string(NULL); - cuser = packet_get_string(NULL); - sig = packet_get_string(&slen); - - debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d", - cuser, chost, pkalg, slen); -#ifdef DEBUG_PK - debug("signature:"); - buffer_init(&b); - buffer_append(&b, sig, slen); - buffer_dump(&b); - buffer_free(&b); -#endif - pktype = key_type_from_name(pkalg); - if (pktype == KEY_UNSPEC) { - /* this is perfectly legal */ - log("userauth_hostbased: unsupported " - "public key algorithm: %s", pkalg); - goto done; - } - key = key_from_blob(pkblob, blen); - if (key == NULL) { - error("userauth_hostbased: cannot decode key: %s", pkalg); - goto done; - } - if (key->type != pktype) { - error("userauth_hostbased: type mismatch for decoded key " - "(received %d, expected %d)", key->type, pktype); - goto done; - } - service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : - authctxt->service; - buffer_init(&b); - buffer_put_string(&b, session_id2, session_id2_len); - /* reconstruct packet */ - buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); - buffer_put_cstring(&b, authctxt->user); - buffer_put_cstring(&b, service); - buffer_put_cstring(&b, "hostbased"); - buffer_put_string(&b, pkalg, alen); - buffer_put_string(&b, pkblob, blen); - buffer_put_cstring(&b, chost); - buffer_put_cstring(&b, cuser); -#ifdef DEBUG_PK - buffer_dump(&b); -#endif - /* test for allowed key and correct signature */ - authenticated = 0; - if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) && - PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b), - buffer_len(&b))) == 1) - authenticated = 1; - - buffer_clear(&b); -done: - debug2("userauth_hostbased: authenticated %d", authenticated); - if (key != NULL) - key_free(key); - xfree(pkalg); - xfree(pkblob); - xfree(cuser); - xfree(chost); - xfree(sig); - return authenticated; -} - -/* get current user */ - -struct passwd* -auth_get_user(void) -{ - return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL; -} - -#define DELIM "," - static char * authmethods_get(void) { - Authmethod *method = NULL; Buffer b; char *list; + int i; buffer_init(&b); - for (method = authmethods; method->name != NULL; method++) { - if (strcmp(method->name, "none") == 0) + for (i = 0; authmethods[i] != NULL; i++) { + if (strcmp(authmethods[i]->name, "none") == 0) continue; - if (method->enabled != NULL && *(method->enabled) != 0) { + if (authmethods[i]->enabled != NULL && + *(authmethods[i]->enabled) != 0) { if (buffer_len(&b) > 0) buffer_append(&b, ",", 1); - buffer_append(&b, method->name, strlen(method->name)); + buffer_append(&b, authmethods[i]->name, + strlen(authmethods[i]->name)); } } buffer_append(&b, "\0", 1); @@ -618,13 +392,16 @@ authmethods_get(void) static Authmethod * authmethod_lookup(const char *name) { - Authmethod *method = NULL; + int i; + if (name != NULL) - for (method = authmethods; method->name != NULL; method++) - if (method->enabled != NULL && - *(method->enabled) != 0 && - strcmp(name, method->name) == 0) - return method; - debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); + for (i = 0; authmethods[i] != NULL; i++) + if (authmethods[i]->enabled != NULL && + *(authmethods[i]->enabled) != 0 && + strcmp(name, authmethods[i]->name) == 0) + return authmethods[i]; + debug2("Unrecognized authentication method name: %s", + name ? name : "NULL"); return NULL; } +