=================================================================== RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/auth2.c,v retrieving revision 1.20 retrieving revision 1.20.2.6 diff -u -r1.20 -r1.20.2.6 --- src/usr.bin/ssh/auth2.c 2000/10/14 12:16:56 1.20 +++ src/usr.bin/ssh/auth2.c 2001/11/15 00:14:59 1.20.2.6 @@ -23,37 +23,39 @@ */ #include "includes.h" -RCSID("$OpenBSD: auth2.c,v 1.20 2000/10/14 12:16:56 markus Exp $"); +RCSID("$OpenBSD: auth2.c,v 1.20.2.6 2001/11/15 00:14:59 miod Exp $"); -#include -#include #include +#include "ssh2.h" #include "xmalloc.h" #include "rsa.h" -#include "ssh.h" -#include "pty.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 "ssh2.h" #include "auth.h" #include "session.h" #include "dispatch.h" -#include "auth.h" #include "key.h" +#include "cipher.h" #include "kex.h" - -#include "dsa.h" +#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" /* import */ extern ServerOptions options; -extern unsigned char *session_id2; +extern u_char *session_id2; extern int session_id2_len; static Authctxt *x_authctxt = NULL; @@ -68,22 +70,23 @@ /* protocol */ -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); +static void input_service_request(int, int, void *); +static void input_userauth_request(int, int, void *); +static void protocol_error(int, int, void *); - /* helper */ -Authmethod *authmethod_lookup(const char *name); -struct passwd *pwcopy(struct passwd *pw); -int user_dsa_key_allowed(struct passwd *pw, Key *key); -char *authmethods_get(void); +static Authmethod *authmethod_lookup(const char *); +static char *authmethods_get(void); +static int user_key_allowed(struct passwd *, Key *); +static int hostbased_key_allowed(struct passwd *, const char *, char *, Key *); /* auth */ -int userauth_none(Authctxt *authctxt); -int userauth_passwd(Authctxt *authctxt); -int userauth_pubkey(Authctxt *authctxt); -int userauth_kbdint(Authctxt *authctxt); +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", @@ -91,13 +94,16 @@ &one}, {"publickey", userauth_pubkey, - &options.dsa_authentication}, - {"keyboard-interactive", - userauth_kbdint, - &options.kbd_interactive_authentication}, + &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} }; @@ -108,24 +114,21 @@ void do_authentication2() { - Authctxt *authctxt = xmalloc(sizeof(*authctxt)); - memset(authctxt, 'a', sizeof(*authctxt)); - authctxt->valid = 0; - authctxt->attempt = 0; - authctxt->success = 0; + Authctxt *authctxt = authctxt_new(); + x_authctxt = authctxt; /*XXX*/ -#ifdef KRB4 - /* turn off kerberos, not supported by SSH2 */ - options.kerberos_authentication = 0; -#endif + /* challenge-response is implemented via keyboard interactive */ + if (options.challenge_response_authentication) + options.kbd_interactive_authentication = 1; + dispatch_init(&protocol_error); dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); - do_authenticated2(); + do_authenticated(authctxt); } -void +static void protocol_error(int type, int plen, void *ctxt) { log("auth: protocol error: type %d plen %d", type, plen); @@ -135,11 +138,11 @@ packet_write_wait(); } -void +static void input_service_request(int type, int plen, void *ctxt) { Authctxt *authctxt = ctxt; - unsigned int len; + u_int len; int accept = 0; char *service = packet_get_string(&len); packet_done(); @@ -168,29 +171,29 @@ xfree(service); } -void +static void input_userauth_request(int type, int plen, void *ctxt) { Authctxt *authctxt = ctxt; Authmethod *m = NULL; - char *user, *service, *method; + char *user, *service, *method, *style = NULL; int authenticated = 0; if (authctxt == NULL) fatal("input_userauth_request: no authctxt"); - if (authctxt->attempt++ >= AUTH_FAIL_MAX) - packet_disconnect("too many failed userauth_requests"); user = packet_get_string(NULL); service = packet_get_string(NULL); method = packet_get_string(NULL); debug("userauth-request for user %s service %s method %s", user, service, method); - debug("attempt #%d", authctxt->attempt); + debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); - if (authctxt->attempt == 1) { + if ((style = strchr(user, ':')) != NULL) + *style++ = 0; + + if (authctxt->attempt++ == 0) { /* setup auth context */ struct passwd *pw = NULL; - setproctitle("%s", user); pw = getpwnam(user); if (pw && allowed_user(pw) && strcmp(service, "ssh-connection")==0) { authctxt->pw = pwcopy(pw); @@ -199,84 +202,59 @@ } else { log("input_userauth_request: illegal user %s", user); } + setproctitle("%s", pw ? user : "unknown"); authctxt->user = xstrdup(user); authctxt->service = xstrdup(service); - } else if (authctxt->valid) { - if (strcmp(user, authctxt->user) != 0 || - strcmp(service, authctxt->service) != 0) { - log("input_userauth_request: missmatch: (%s,%s)!=(%s,%s)", - user, service, authctxt->user, authctxt->service); - authctxt->valid = 0; - } + authctxt->style = style ? xstrdup(style) : NULL; + } 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); } + /* reset state */ + 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); if (m != NULL) { debug2("input_userauth_request: try method %s", method); authenticated = m->userauth(authctxt); - } else { - debug2("input_userauth_request: unsupported method %s", method); } - if (!authctxt->valid && authenticated == 1) { - log("input_userauth_request: INTERNAL ERROR: authenticated invalid user %s service %s", user, method); - authenticated = 0; - } + userauth_finish(authctxt, authenticated, method); - /* Special handling for root */ - if (authenticated == 1 && - authctxt->valid && authctxt->pw->pw_uid == 0 && !options.permit_root_login) { - authenticated = 0; - log("ROOT LOGIN REFUSED FROM %.200s", get_canonical_hostname()); - } - - /* Log before sending the reply */ - userauth_log(authctxt, authenticated, method); - userauth_reply(authctxt, authenticated); - xfree(service); xfree(user); xfree(method); } - void -userauth_log(Authctxt *authctxt, int authenticated, char *method) +userauth_finish(Authctxt *authctxt, int authenticated, char *method) { - void (*authlog) (const char *fmt,...) = verbose; - char *user = NULL, *authmsg = NULL; + char *methods; - /* Raise logging level */ - if (authenticated == 1 || - !authctxt->valid || - authctxt->attempt >= AUTH_FAIL_LOG || - strcmp(method, "password") == 0) - authlog = log; + if (!authctxt->valid && authenticated) + fatal("INTERNAL ERROR: authenticated invalid user %s", + authctxt->user); - if (authenticated == 1) { - authmsg = "Accepted"; - } else if (authenticated == 0) { - authmsg = "Failed"; - } else { - authmsg = "Postponed"; - } + /* Special handling for root */ + if (authenticated && authctxt->pw->pw_uid == 0 && + !auth_root_allowed(method)) + authenticated = 0; - if (authctxt->valid) { - user = authctxt->pw->pw_uid == 0 ? "ROOT" : authctxt->user; - } else { - user = "NOUSER"; - } + /* Log before sending the reply */ + auth_log(authctxt, authenticated, method, " ssh2"); - authlog("%s %s for %.200s from %.200s port %d ssh2", - authmsg, - method, - user, - get_remote_ipaddr(), - get_remote_port()); -} + if (authctxt->postponed) + return; -void -userauth_reply(Authctxt *authctxt, int authenticated) -{ /* XXX todo: check if multiple auth methods are needed */ if (authenticated == 1) { /* turn off userauth */ @@ -286,20 +264,51 @@ packet_write_wait(); /* now we can break out */ authctxt->success = 1; - } else if (authenticated == 0) { - char *methods = authmethods_get(); + } else { + if (authctxt->failures++ > AUTH_FAIL_MAX) + packet_disconnect(AUTH_FAIL_MSG, authctxt->user); + methods = authmethods_get(); packet_start(SSH2_MSG_USERAUTH_FAILURE); packet_put_cstring(methods); packet_put_char(0); /* XXX partial success, unused */ packet_send(); packet_write_wait(); xfree(methods); - } else { - /* do nothing, we did already send a reply */ } } -int +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 */ @@ -307,59 +316,58 @@ if (m != NULL) m->enabled = NULL; packet_done(); - return authctxt->valid ? auth_password(authctxt->pw, "") : 0; + userauth_banner(); + return authctxt->valid ? auth_password(authctxt, "") : 0; } -int +static int userauth_passwd(Authctxt *authctxt) { char *password; int authenticated = 0; int change; - unsigned int len; + u_int len; change = packet_get_char(); if (change) log("password change not supported"); password = packet_get_string(&len); packet_done(); if (authctxt->valid && - auth_password(authctxt->pw, password) == 1) + auth_password(authctxt, password) == 1) authenticated = 1; memset(password, 0, len); xfree(password); return authenticated; } -int +static int userauth_kbdint(Authctxt *authctxt) { int authenticated = 0; - char *lang = NULL; - char *devs = NULL; - + char *lang, *devs; + lang = packet_get_string(NULL); devs = packet_get_string(NULL); packet_done(); - debug("keyboard-interactive language %s devs %s", lang, devs); -#ifdef SKEY - /* XXX hardcoded, we should look at devs */ - if (options.skey_authentication != 0) - authenticated = auth2_skey(authctxt); -#endif - xfree(lang); + debug("keyboard-interactive devs %s", devs); + + if (options.challenge_response_authentication) + authenticated = auth2_challenge(authctxt, devs); + xfree(devs); + xfree(lang); return authenticated; } -int +static int userauth_pubkey(Authctxt *authctxt) { Buffer b; Key *key; char *pkalg, *pkblob, *sig; - unsigned int alen, blen, slen; - int have_sig; + u_int alen, blen, slen; + int have_sig, pktype; int authenticated = 0; if (!authctxt->valid) { @@ -367,14 +375,28 @@ return 0; } have_sig = packet_get_char(); - pkalg = packet_get_string(&alen); - if (strcmp(pkalg, KEX_DSS) != 0) { - log("bad pkalg %s", pkalg); /*XXX*/ + 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); xfree(pkalg); + xfree(pkblob); return 0; } - pkblob = packet_get_string(&blen); - key = dsa_key_from_blob(pkblob, blen); + key = key_from_blob(pkblob, blen); if (key != NULL) { if (have_sig) { sig = packet_get_string(&slen); @@ -389,19 +411,23 @@ buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); buffer_put_cstring(&b, authctxt->user); buffer_put_cstring(&b, - datafellows & SSH_BUG_PUBKEYAUTH ? + datafellows & SSH_BUG_PKSERVICE ? "ssh-userauth" : authctxt->service); - buffer_put_cstring(&b, "publickey"); - buffer_put_char(&b, have_sig); - buffer_put_cstring(&b, KEX_DSS); + 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_DSS +#ifdef DEBUG_PK buffer_dump(&b); #endif /* test for correct signature */ - if (user_dsa_key_allowed(authctxt->pw, key) && - dsa_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1) + 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); @@ -417,24 +443,100 @@ * if a user is not allowed to login. is this an * issue? -markus */ - if (user_dsa_key_allowed(authctxt->pw, key)) { + 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(); - authenticated = -1; + authctxt->postponed = 1; } } if (authenticated != 1) auth_clear_options(); key_free(key); } + debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg); xfree(pkalg); xfree(pkblob); return authenticated; } +static int +userauth_hostbased(Authctxt *authctxt) +{ + Buffer b; + Key *key; + char *pkalg, *pkblob, *sig, *cuser, *chost, *service; + 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) { + debug("userauth_hostbased: cannot decode key: %s", pkalg); + 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 */ + 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); + xfree(pkalg); + xfree(pkblob); + xfree(cuser); + xfree(chost); + xfree(sig); + return authenticated; +} + /* get current user */ struct passwd* @@ -445,11 +547,11 @@ #define DELIM "," -char * +static char * authmethods_get(void) { Authmethod *method = NULL; - unsigned int size = 0; + u_int size = 0; char *list; for (method = authmethods; method->name != NULL; method++) { @@ -477,7 +579,7 @@ return list; } -Authmethod * +static Authmethod * authmethod_lookup(const char *name) { Authmethod *method = NULL; @@ -492,14 +594,13 @@ } /* return 1 if user allows given key */ -int -user_dsa_key_allowed(struct passwd *pw, Key *key) +static int +user_key_allowed2(struct passwd *pw, Key *key, char *file) { - char line[8192], file[1024]; + char line[8192]; int found_key = 0; - unsigned int bits = -1; FILE *f; - unsigned long linenum = 0; + u_long linenum = 0; struct stat st; Key *found; @@ -507,11 +608,9 @@ return 0; /* Temporarily use the user's uid. */ - temporarily_use_uid(pw->pw_uid); + temporarily_use_uid(pw); - /* The authorized keys. */ - snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir, - SSH_USER_PERMITTED_KEYS2); + debug("trying public key file %s", file); /* Fail quietly if file does not exist */ if (stat(file, &st) < 0) { @@ -526,46 +625,14 @@ 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 SSH_USER_PERMITTED_KEYS */ - int i; - static const char *check[] = { - "", 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; - } + 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); @@ -578,10 +645,10 @@ if (!*cp || *cp == '\n' || *cp == '#') continue; - bits = key_read(found, &cp); - if (bits == 0) { + 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] == '"') @@ -592,16 +659,16 @@ /* Skip remaining whitespace. */ for (; *cp == ' ' || *cp == '\t'; cp++) ; - bits = key_read(found, &cp); - if (bits == 0) { + 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, linenum) == 1) { + auth_parse_options(pw, options, file, linenum) == 1) { found_key = 1; - debug("matching key found: file %s, line %ld", + debug("matching key found: file %s, line %lu", file, linenum); break; } @@ -609,20 +676,75 @@ restore_uid(); fclose(f); key_free(found); + if (!found_key) + debug2("key not found"); return found_key; } -struct passwd * -pwcopy(struct passwd *pw) +/* check whether given key is in .ssh/authorized_keys* */ +static int +user_key_allowed(struct passwd *pw, Key *key) { - struct passwd *copy = xmalloc(sizeof(*copy)); - memset(copy, 0, sizeof(*copy)); - copy->pw_name = xstrdup(pw->pw_name); - copy->pw_passwd = xstrdup(pw->pw_passwd); - copy->pw_uid = pw->pw_uid; - copy->pw_gid = pw->pw_gid; - copy->pw_class = xstrdup(pw->pw_class); - copy->pw_dir = xstrdup(pw->pw_dir); - copy->pw_shell = xstrdup(pw->pw_shell); - return copy; + 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 */ +static int +hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost, + Key *key) +{ + const char *resolvedname, *ipaddr, *lookup; + int host_status, len; + + resolvedname = get_canonical_hostname(options.reverse_mapping_check); + 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); +} +