=================================================================== RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/auth2.c,v retrieving revision 1.89 retrieving revision 1.89.2.4 diff -u -r1.89 -r1.89.2.4 --- src/usr.bin/ssh/auth2.c 2002/03/19 14:27:39 1.89 +++ src/usr.bin/ssh/auth2.c 2002/10/11 14:51:52 1.89.2.4 @@ -23,33 +23,17 @@ */ #include "includes.h" -RCSID("$OpenBSD: auth2.c,v 1.89 2002/03/19 14:27:39 markus Exp $"); +RCSID("$OpenBSD: auth2.c,v 1.89.2.4 2002/10/11 14:51:52 miod Exp $"); -#include - #include "ssh2.h" #include "xmalloc.h" -#include "rsa.h" -#include "sshpty.h" #include "packet.h" -#include "buffer.h" #include "log.h" #include "servconf.h" #include "compat.h" -#include "channels.h" -#include "bufaux.h" #include "auth.h" -#include "session.h" #include "dispatch.h" -#include "key.h" -#include "cipher.h" -#include "kex.h" #include "pathnames.h" -#include "uidswap.h" -#include "auth-options.h" -#include "hostfile.h" -#include "canohost.h" -#include "match.h" #include "monitor_wrap.h" /* import */ @@ -58,13 +42,22 @@ extern int session_id2_len; Authctxt *x_authctxt = NULL; -static int one = 1; -typedef struct Authmethod Authmethod; -struct Authmethod { - char *name; - int (*userauth)(Authctxt *authctxt); - int *enabled; +/* methods */ + +extern Authmethod method_none; +extern Authmethod method_pubkey; +extern Authmethod method_passwd; +extern Authmethod method_kbdint; +extern Authmethod method_hostbased; + +Authmethod *authmethods[] = { + &method_none, + &method_pubkey, + &method_passwd, + &method_kbdint, + &method_hostbased, + NULL }; /* protocol */ @@ -78,33 +71,6 @@ int user_key_allowed(struct passwd *, Key *); int hostbased_key_allowed(struct passwd *, const char *, char *, 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 *); - -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 */ @@ -132,7 +98,7 @@ { Authctxt *authctxt = ctxt; u_int len; - int accept = 0; + int acceptit = 0; char *service = packet_get_string(&len); packet_check_eom(); @@ -141,14 +107,14 @@ 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(); @@ -229,7 +195,8 @@ authctxt->user); /* Special handling for root */ - if (authenticated && authctxt->pw->pw_uid == 0 && + if (!use_privsep && + authenticated && authctxt->pw->pw_uid == 0 && !auth_root_allowed(method)) authenticated = 0; @@ -261,285 +228,6 @@ } } -static 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; -} - -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(); - return (authctxt->valid ? PRIVSEP(auth_password(authctxt, "")) : 0); -} - -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 && - 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); - - xfree(devs); - xfree(lang); - 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); - 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* @@ -553,18 +241,20 @@ 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); @@ -576,174 +266,15 @@ 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; -} - -/* return 1 if user allows given key */ -static int -user_key_allowed2(struct passwd *pw, Key *key, char *file) -{ - char line[8192]; - int found_key = 0; - FILE *f; - u_long linenum = 0; - struct stat st; - Key *found; - char *fp; - - if (pw == NULL) - return 0; - - /* Temporarily use the user's uid. */ - temporarily_use_uid(pw); - - debug("trying public key file %s", file); - - /* Fail quietly if file does not exist */ - if (stat(file, &st) < 0) { - /* Restore the privileged uid. */ - restore_uid(); - return 0; - } - /* Open the file containing the authorized keys. */ - f = fopen(file, "r"); - if (!f) { - /* Restore the privileged uid. */ - 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; - } - - found_key = 0; - found = key_new(key->type); - - while (fgets(line, sizeof(line), f)) { - char *cp, *options = NULL; - linenum++; - /* Skip leading whitespace, empty and comment lines. */ - for (cp = line; *cp == ' ' || *cp == '\t'; cp++) - ; - if (!*cp || *cp == '\n' || *cp == '#') - continue; - - 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); - options = cp; - for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) { - if (*cp == '\\' && cp[1] == '"') - cp++; /* Skip both */ - else if (*cp == '"') - quoted = !quoted; - } - /* Skip remaining whitespace. */ - for (; *cp == ' ' || *cp == '\t'; cp++) - ; - if (key_read(found, &cp) != 1) { - debug2("user_key_allowed: advance: '%s'", cp); - /* still no key? advance to next line*/ - continue; - } - } - if (key_equal(found, key) && - auth_parse_options(pw, options, file, linenum) == 1) { - found_key = 1; - debug("matching key found: file %s, line %lu", - 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; - } - } - restore_uid(); - fclose(f); - key_free(found); - if (!found_key) - debug2("key not found"); - 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) -{ - const char *resolvedname, *ipaddr, *lookup; - HostStatus host_status; - int len; - - resolvedname = get_canonical_hostname(options.verify_reverse_mapping); - ipaddr = get_remote_ipaddr(); - - debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s", - chost, resolvedname, ipaddr); - - if (options.hostbased_uses_name_from_packet_only) { - if (auth_rhosts2(pw, cuser, chost, chost) == 0) - return 0; - lookup = chost; - } else { - if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') { - debug2("stripping trailing dot from chost %s", chost); - chost[len - 1] = '\0'; - } - if (strcasecmp(resolvedname, chost) != 0) - log("userauth_hostbased mismatch: " - "client sends %s, but we resolve %s to %s", - chost, ipaddr, resolvedname); - if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0) - return 0; - lookup = resolvedname; - } - 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); - - /* 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); - - return (host_status == HOST_OK); }