=================================================================== RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/auth2.c,v retrieving revision 1.56.2.5 retrieving revision 1.57 diff -u -r1.56.2.5 -r1.57 --- src/usr.bin/ssh/auth2.c 2002/06/02 22:56:09 1.56.2.5 +++ src/usr.bin/ssh/auth2.c 2001/05/18 14:13:28 1.57 @@ -23,7 +23,7 @@ */ #include "includes.h" -RCSID("$OpenBSD: auth2.c,v 1.56.2.5 2002/06/02 22:56:09 miod Exp $"); +RCSID("$OpenBSD: auth2.c,v 1.57 2001/05/18 14:13:28 markus Exp $"); #include @@ -47,18 +47,18 @@ #include "pathnames.h" #include "uidswap.h" #include "auth-options.h" +#include "misc.h" #include "hostfile.h" #include "canohost.h" +#include "tildexpand.h" #include "match.h" -#include "monitor_wrap.h" -#include "atomicio.h" /* import */ extern ServerOptions options; extern u_char *session_id2; extern int session_id2_len; -Authctxt *x_authctxt = NULL; +static Authctxt *x_authctxt = NULL; static int one = 1; typedef struct Authmethod Authmethod; @@ -70,22 +70,26 @@ /* protocol */ -static void input_service_request(int, u_int32_t, void *); -static void input_userauth_request(int, u_int32_t, void *); +void input_service_request(int type, int plen, void *ctxt); +void input_userauth_request(int type, int plen, void *ctxt); +void protocol_error(int type, int plen, void *ctxt); /* 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 *); +Authmethod *authmethod_lookup(const char *name); +char *authmethods_get(void); +int user_key_allowed(struct passwd *pw, Key *key); +int +hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost, + Key *key); /* auth */ -static void userauth_banner(void); -static int userauth_none(Authctxt *); -static int userauth_passwd(Authctxt *); -static int userauth_pubkey(Authctxt *); -static int userauth_hostbased(Authctxt *); -static int userauth_kbdint(Authctxt *); +void userauth_banner(void); +void userauth_reply(Authctxt *authctxt, int authenticated); +int userauth_none(Authctxt *authctxt); +int userauth_passwd(Authctxt *authctxt); +int userauth_pubkey(Authctxt *authctxt); +int userauth_hostbased(Authctxt *authctxt); +int userauth_kbdint(Authctxt *authctxt); Authmethod authmethods[] = { {"none", @@ -110,32 +114,41 @@ * loop until authctxt->success == TRUE */ -Authctxt * -do_authentication2(void) +void +do_authentication2() { Authctxt *authctxt = authctxt_new(); x_authctxt = authctxt; /*XXX*/ - /* challenge-response is implemented via keyboard interactive */ + /* challenge-reponse is implemented via keyboard interactive */ if (options.challenge_response_authentication) options.kbd_interactive_authentication = 1; - dispatch_init(&dispatch_protocol_error); + dispatch_init(&protocol_error); dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); + do_authenticated(authctxt); +} - return (authctxt); +void +protocol_error(int type, int plen, void *ctxt) +{ + log("auth: protocol error: type %d plen %d", type, plen); + packet_start(SSH2_MSG_UNIMPLEMENTED); + packet_put_int(0); + packet_send(); + packet_write_wait(); } -static void -input_service_request(int type, u_int32_t seq, void *ctxt) +void +input_service_request(int type, int plen, void *ctxt) { Authctxt *authctxt = ctxt; u_int len; int accept = 0; char *service = packet_get_string(&len); - packet_check_eom(); + packet_done(); if (authctxt == NULL) fatal("input_service_request: no authctxt"); @@ -161,8 +174,8 @@ xfree(service); } -static void -input_userauth_request(int type, u_int32_t seq, void *ctxt) +void +input_userauth_request(int type, int plen, void *ctxt) { Authctxt *authctxt = ctxt; Authmethod *m = NULL; @@ -183,29 +196,36 @@ if (authctxt->attempt++ == 0) { /* setup auth context */ - authctxt->pw = PRIVSEP(getpwnamallow(user)); - if (authctxt->pw && strcmp(service, "ssh-connection")==0) { + struct passwd *pw = NULL; + pw = getpwnam(user); + if (pw && allowed_user(pw) && strcmp(service, "ssh-connection")==0) { + authctxt->pw = pwcopy(pw); authctxt->valid = 1; debug2("input_userauth_request: setting up authctxt for %s", user); } else { log("input_userauth_request: illegal user %s", user); } - setproctitle("%s%s", authctxt->pw ? user : "unknown", - use_privsep ? " [net]" : ""); + setproctitle("%s", pw ? user : "unknown"); authctxt->user = xstrdup(user); authctxt->service = xstrdup(service); - authctxt->style = style ? xstrdup(style) : NULL; - if (use_privsep) - mm_inform_authserv(service, style); - } else if (strcmp(user, authctxt->user) != 0 || - strcmp(service, authctxt->service) != 0) { - packet_disconnect("Change of username or service not allowed: " - "(%s,%s) -> (%s,%s)", - authctxt->user, authctxt->service, user, service); + authctxt->style = style ? xstrdup(style) : NULL; /* currently unused */ + } else if (authctxt->valid) { + if (strcmp(user, authctxt->user) != 0 || + strcmp(service, authctxt->service) != 0) { + log("input_userauth_request: mismatch: (%s,%s)!=(%s,%s)", + user, service, authctxt->user, authctxt->service); + authctxt->valid = 0; + } } /* reset state */ - auth2_challenge_stop(authctxt); + dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, &protocol_error); authctxt->postponed = 0; +#ifdef BSD_AUTH + if (authctxt->as) { + auth_close(authctxt->as); + authctxt->as = NULL; + } +#endif /* try to authenticate user */ m = authmethod_lookup(method); @@ -223,8 +243,6 @@ void userauth_finish(Authctxt *authctxt, int authenticated, char *method) { - char *methods; - if (!authctxt->valid && authenticated) fatal("INTERNAL ERROR: authenticated invalid user %s", authctxt->user); @@ -237,13 +255,50 @@ /* Log before sending the reply */ auth_log(authctxt, authenticated, method, " ssh2"); - if (authctxt->postponed) + if (!authctxt->postponed) + userauth_reply(authctxt, authenticated); +} + +void +userauth_banner(void) +{ + struct stat st; + char *banner = NULL; + off_t len, n; + int fd; + + if (options.banner == NULL || (datafellows & SSH_BUG_BANNER)) return; + if ((fd = open(options.banner, O_RDONLY)) < 0) + return; + if (fstat(fd, &st) < 0) + goto done; + len = st.st_size; + banner = xmalloc(len + 1); + if ((n = read(fd, banner, len)) < 0) + goto done; + banner[n] = '\0'; + 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); + close(fd); + return; +} +void +userauth_reply(Authctxt *authctxt, int authenticated) +{ + char *methods; + /* XXX todo: check if multiple auth methods are needed */ if (authenticated == 1) { /* turn off userauth */ - dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); + dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &protocol_error); packet_start(SSH2_MSG_USERAUTH_SUCCESS); packet_send(); packet_write_wait(); @@ -262,69 +317,19 @@ } } -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 +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(); + packet_done(); userauth_banner(); - return (authctxt->valid ? PRIVSEP(auth_password(authctxt, "")) : 0); + return authctxt->valid ? auth_password(authctxt, "") : 0; } -static int +int userauth_passwd(Authctxt *authctxt) { char *password; @@ -335,24 +340,24 @@ if (change) log("password change not supported"); password = packet_get_string(&len); - packet_check_eom(); + packet_done(); if (authctxt->valid && - PRIVSEP(auth_password(authctxt, password)) == 1) + auth_password(authctxt, password) == 1) authenticated = 1; memset(password, 0, len); xfree(password); return authenticated; } -static int +int userauth_kbdint(Authctxt *authctxt) { int authenticated = 0; char *lang, *devs; - + lang = packet_get_string(NULL); devs = packet_get_string(NULL); - packet_check_eom(); + packet_done(); debug("keyboard-interactive devs %s", devs); @@ -364,13 +369,12 @@ return authenticated; } -static int +int userauth_pubkey(Authctxt *authctxt) { Buffer b; - Key *key = NULL; - char *pkalg; - u_char *pkblob, *sig; + Key *key; + char *pkalg, *pkblob, *sig; u_int alen, blen, slen; int have_sig, pktype; int authenticated = 0; @@ -396,94 +400,83 @@ 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; + log("userauth_pubkey: unsupported public key algorithm: %s", pkalg); + xfree(pkalg); + xfree(pkblob); + return 0; } 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); + if (key != NULL) { + if (have_sig) { + sig = packet_get_string(&slen); + packet_done(); + 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); + 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(); + /* test for correct signature */ + if (user_key_allowed(authctxt->pw, key) && + 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_done(); - /* 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; + /* 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 (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(); + key_free(key); } - 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); return authenticated; } -static int +int userauth_hostbased(Authctxt *authctxt) { Buffer b; - Key *key = NULL; - char *pkalg, *cuser, *chost, *service; - u_char *pkblob, *sig; + Key *key; + char *pkalg, *pkblob, *sig, *cuser, *chost, *service; u_int alen, blen, slen; int pktype; int authenticated = 0; @@ -516,14 +509,9 @@ } key = key_from_blob(pkblob, blen); if (key == NULL) { - error("userauth_hostbased: cannot decode key: %s", pkalg); + debug("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); @@ -541,17 +529,15 @@ 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) + if (hostbased_key_allowed(authctxt->pw, cuser, chost, key) && + key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1) authenticated = 1; buffer_clear(&b); + key_free(key); + done: debug2("userauth_hostbased: authenticated %d", authenticated); - if (key != NULL) - key_free(key); xfree(pkalg); xfree(pkblob); xfree(cuser); @@ -570,30 +556,39 @@ #define DELIM "," -static char * +char * authmethods_get(void) { Authmethod *method = NULL; - Buffer b; + u_int size = 0; char *list; - buffer_init(&b); for (method = authmethods; method->name != NULL; method++) { if (strcmp(method->name, "none") == 0) continue; if (method->enabled != NULL && *(method->enabled) != 0) { - if (buffer_len(&b) > 0) - buffer_append(&b, ",", 1); - buffer_append(&b, method->name, strlen(method->name)); + if (size != 0) + size += strlen(DELIM); + size += strlen(method->name); } } - buffer_append(&b, "\0", 1); - list = xstrdup(buffer_ptr(&b)); - buffer_free(&b); + size++; /* trailing '\0' */ + list = xmalloc(size); + list[0] = '\0'; + + for (method = authmethods; method->name != NULL; method++) { + if (strcmp(method->name, "none") == 0) + continue; + if (method->enabled != NULL && *(method->enabled) != 0) { + if (list[0] != '\0') + strlcat(list, DELIM, size); + strlcat(list, method->name, size); + } + } return list; } -static Authmethod * +Authmethod * authmethod_lookup(const char *name) { Authmethod *method = NULL; @@ -608,16 +603,15 @@ } /* return 1 if user allows given key */ -static int -user_key_allowed2(struct passwd *pw, Key *key, char *file) +int +user_key_allowed(struct passwd *pw, Key *key) { - char line[8192]; + char line[8192], file[MAXPATHLEN]; int found_key = 0; FILE *f; u_long linenum = 0; struct stat st; Key *found; - char *fp; if (pw == NULL) return 0; @@ -625,7 +619,9 @@ /* Temporarily use the user's uid. */ temporarily_use_uid(pw); - debug("trying public key file %s", file); + /* The authorized keys. */ + snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir, + _PATH_SSH_USER_PERMITTED_KEYS2); /* Fail quietly if file does not exist */ if (stat(file, &st) < 0) { @@ -640,14 +636,46 @@ restore_uid(); return 0; } - if (options.strict_modes && - secure_filename(f, file, pw, line, sizeof(line)) != 0) { - fclose(f); - log("Authentication refused: %s", line); - restore_uid(); - return 0; + if (options.strict_modes) { + int fail = 0; + char buf[1024]; + /* Check open file in order to avoid open/stat races */ + if (fstat(fileno(f), &st) < 0 || + (st.st_uid != 0 && st.st_uid != pw->pw_uid) || + (st.st_mode & 022) != 0) { + snprintf(buf, sizeof buf, + "%s authentication refused for %.100s: " + "bad ownership or modes for '%s'.", + key_type(key), pw->pw_name, file); + fail = 1; + } else { + /* Check path to _PATH_SSH_USER_PERMITTED_KEYS */ + int i; + static const char *check[] = { + "", _PATH_SSH_USER_DIR, NULL + }; + for (i = 0; check[i]; i++) { + snprintf(line, sizeof line, "%.500s/%.100s", + pw->pw_dir, check[i]); + if (stat(line, &st) < 0 || + (st.st_uid != 0 && st.st_uid != pw->pw_uid) || + (st.st_mode & 022) != 0) { + snprintf(buf, sizeof buf, + "%s authentication refused for %.100s: " + "bad ownership or modes for '%s'.", + key_type(key), pw->pw_name, line); + fail = 1; + break; + } + } + } + if (fail) { + fclose(f); + log("%s", buf); + restore_uid(); + return 0; + } } - found_key = 0; found = key_new(key->type); @@ -660,7 +688,7 @@ if (!*cp || *cp == '\n' || *cp == '#') continue; - if (key_read(found, &cp) != 1) { + if (key_read(found, &cp) == -1) { /* no key? check if there are options for this key */ int quoted = 0; debug2("user_key_allowed: check options: '%s'", cp); @@ -674,7 +702,7 @@ /* Skip remaining whitespace. */ for (; *cp == ' ' || *cp == '\t'; cp++) ; - if (key_read(found, &cp) != 1) { + if (key_read(found, &cp) == -1) { debug2("user_key_allowed: advance: '%s'", cp); /* still no key? advance to next line*/ continue; @@ -683,12 +711,8 @@ if (key_equal(found, key) && auth_parse_options(pw, options, file, linenum) == 1) { found_key = 1; - debug("matching key found: file %s, line %lu", + debug("matching key found: file %s, line %ld", file, linenum); - fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX); - verbose("Found matching %s key: %s", - key_type(found), fp); - xfree(fp); break; } } @@ -700,36 +724,18 @@ return found_key; } -/* check whether given key is in .ssh/authorized_keys* */ -int -user_key_allowed(struct passwd *pw, Key *key) -{ - int success; - char *file; - - file = authorized_keys_file(pw); - success = user_key_allowed2(pw, key, file); - xfree(file); - if (success) - return success; - - /* try suffix "2" for backward compat, too */ - file = authorized_keys_file2(pw); - success = user_key_allowed2(pw, key, file); - xfree(file); - return success; -} - /* return 1 if given hostkey is allowed */ int hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost, Key *key) { + Key *found; const char *resolvedname, *ipaddr, *lookup; - HostStatus host_status; - int len; + struct stat st; + char *user_hostfile; + int host_status, len; - resolvedname = get_canonical_hostname(options.verify_reverse_mapping); + resolvedname = get_canonical_hostname(options.reverse_mapping_check); ipaddr = get_remote_ipaddr(); debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s", @@ -754,16 +760,32 @@ } debug2("userauth_hostbased: access allowed by auth_rhosts2"); - host_status = check_key_in_hostfiles(pw, key, lookup, - _PATH_SSH_SYSTEM_HOSTFILE, - options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE); + /* XXX this is copied from auth-rh-rsa.c and should be shared */ + found = key_new(key->type); + host_status = check_host_in_hostfile(_PATH_SSH_SYSTEM_HOSTFILE2, lookup, + key, found, NULL); - /* backward compat if no key has been found. */ - if (host_status == HOST_NEW) - host_status = check_key_in_hostfiles(pw, key, lookup, - _PATH_SSH_SYSTEM_HOSTFILE2, - options.ignore_user_known_hosts ? NULL : - _PATH_SSH_USER_HOSTFILE2); + if (host_status != HOST_OK && !options.ignore_user_known_hosts) { + user_hostfile = tilde_expand_filename(_PATH_SSH_USER_HOSTFILE2, + pw->pw_uid); + if (options.strict_modes && + (stat(user_hostfile, &st) == 0) && + ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || + (st.st_mode & 022) != 0)) { + log("Hostbased authentication refused for %.100s: " + "bad owner or modes for %.200s", + pw->pw_name, user_hostfile); + } else { + temporarily_use_uid(pw); + host_status = check_host_in_hostfile(user_hostfile, + lookup, key, found, NULL); + restore_uid(); + } + xfree(user_hostfile); + } + key_free(found); + debug2("userauth_hostbased: key %s for %s", host_status == HOST_OK ? + "ok" : "not found", lookup); return (host_status == HOST_OK); }