=================================================================== RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/auth2.c,v retrieving revision 1.8.2.4 retrieving revision 1.9 diff -u -r1.8.2.4 -r1.9 --- src/usr.bin/ssh/auth2.c 2001/03/21 18:52:35 1.8.2.4 +++ src/usr.bin/ssh/auth2.c 2000/06/18 01:09:10 1.9 @@ -9,6 +9,11 @@ * 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. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by Markus Friedl. + * 4. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES @@ -21,106 +26,88 @@ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ - #include "includes.h" -RCSID("$OpenBSD: auth2.c,v 1.8.2.4 2001/03/21 18:52:35 jason Exp $"); +RCSID("$OpenBSD: auth2.c,v 1.9 2000/06/18 01:09:10 markus Exp $"); +#include +#include #include -#include "ssh2.h" #include "xmalloc.h" #include "rsa.h" -#include "sshpty.h" +#include "ssh.h" +#include "pty.h" #include "packet.h" #include "buffer.h" -#include "log.h" +#include "cipher.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 "pathnames.h" + +#include "dsa.h" #include "uidswap.h" -#include "auth-options.h" -#include "misc.h" /* import */ extern ServerOptions options; -extern u_char *session_id2; +extern unsigned char *session_id2; extern int session_id2_len; -static Authctxt *x_authctxt = NULL; -static int one = 1; - -typedef struct Authmethod Authmethod; -struct Authmethod { - char *name; - int (*userauth)(Authctxt *authctxt); - int *enabled; -}; - /* 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); +void input_service_request(int type, int plen); +void input_userauth_request(int type, int plen); +void protocol_error(int type, int plen); -/* helper */ -Authmethod *authmethod_lookup(const char *name); -int user_key_allowed(struct passwd *pw, Key *key); -char *authmethods_get(void); - /* auth */ -void userauth_banner(void); -int userauth_none(Authctxt *authctxt); -int userauth_passwd(Authctxt *authctxt); -int userauth_pubkey(Authctxt *authctxt); -int userauth_kbdint(Authctxt *authctxt); +int ssh2_auth_none(struct passwd *pw); +int ssh2_auth_password(struct passwd *pw); +int ssh2_auth_pubkey(struct passwd *pw, char *service); -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}, - {NULL, NULL, NULL} +/* helper */ +struct passwd* auth_set_user(char *u, char *s); +int user_dsa_key_allowed(struct passwd *pw, Key *key); + +typedef struct Authctxt Authctxt; +struct Authctxt { + char *user; + char *service; + struct passwd pw; + int valid; }; +static Authctxt *authctxt = NULL; +static int userauth_success = 0; /* - * loop until authctxt->success == TRUE + * loop until userauth_success == TRUE */ void do_authentication2() { - Authctxt *authctxt = authctxt_new(); + /* turn off skey/kerberos, not supported by SSH2 */ +#ifdef SKEY + options.skey_authentication = 0; +#endif +#ifdef KRB4 + options.kerberos_authentication = 0; +#endif - x_authctxt = authctxt; /*XXX*/ - - /* challenge-reponse is implemented via keyboard interactive */ - if (options.challenge_reponse_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(authctxt); + dispatch_run(DISPATCH_BLOCK, &userauth_success); + do_authenticated2(); } void -protocol_error(int type, int plen, void *ctxt) +protocol_error(int type, int plen) { log("auth: protocol error: type %d plen %d", type, plen); packet_start(SSH2_MSG_UNIMPLEMENTED); @@ -130,19 +117,15 @@ } void -input_service_request(int type, int plen, void *ctxt) +input_service_request(int type, int plen) { - Authctxt *authctxt = ctxt; - u_int len; + unsigned int len; int accept = 0; char *service = packet_get_string(&len); packet_done(); - if (authctxt == NULL) - fatal("input_service_request: no authctxt"); - if (strcmp(service, "ssh-userauth") == 0) { - if (!authctxt->success) { + if (!userauth_success) { accept = 1; /* now we can handle user-auth requests */ dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); @@ -163,117 +146,61 @@ } void -input_userauth_request(int type, int plen, void *ctxt) +input_userauth_request(int type, int plen) { - Authctxt *authctxt = ctxt; - Authmethod *m = NULL; - char *user, *service, *method, *style = NULL; + static void (*authlog) (const char *fmt,...) = verbose; + static int attempt = 0; + unsigned int len; int authenticated = 0; + char *user, *service, *method, *authmsg = NULL; + struct passwd *pw; - if (authctxt == NULL) - fatal("input_userauth_request: no authctxt"); + if (++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); + user = packet_get_string(&len); + service = packet_get_string(&len); + method = packet_get_string(&len); debug("userauth-request for user %s service %s method %s", user, service, method); - debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); - if ((style = strchr(user, ':')) != NULL) - *style++ = 0; - - if (authctxt->attempt++ == 0) { - /* setup auth context */ - 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); + /* XXX we only allow the ssh-connection service */ + pw = auth_set_user(user, service); + if (pw && strcmp(service, "ssh-connection")==0) { + if (strcmp(method, "none") == 0) { + authenticated = ssh2_auth_none(pw); + } else if (strcmp(method, "password") == 0) { + authenticated = ssh2_auth_password(pw); + } else if (strcmp(method, "publickey") == 0) { + authenticated = ssh2_auth_pubkey(pw, service); } - setproctitle("%s", pw ? user : "unknown"); - authctxt->user = xstrdup(user); - authctxt->service = xstrdup(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: missmatch: (%s,%s)!=(%s,%s)", - user, service, authctxt->user, authctxt->service); - authctxt->valid = 0; - } } - /* reset state */ - dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, &protocol_error); - authctxt->postponed = 0; - - /* try to authenticate user */ - m = authmethod_lookup(method); - if (m != NULL) { - debug2("input_userauth_request: try method %s", method); - authenticated = m->userauth(authctxt); + if (authenticated && pw && pw->pw_uid == 0 && !options.permit_root_login) { + authenticated = 0; + log("ROOT LOGIN REFUSED FROM %.200s", + get_canonical_hostname()); } - if (!authctxt->valid && authenticated) - fatal("INTERNAL ERROR: authenticated invalid user %s", - authctxt->user); - /* Special handling for root */ - if (authenticated && authctxt->pw->pw_uid == 0 && - !auth_root_allowed(method)) - authenticated = 0; + /* Raise logging level */ + if (authenticated == 1 || + attempt == AUTH_FAIL_LOG || + strcmp(method, "password") == 0) + authlog = log; /* Log before sending the reply */ - auth_log(authctxt, authenticated, method, " ssh2"); - - if (!authctxt->postponed) - userauth_reply(authctxt, authenticated); - - xfree(service); - xfree(user); - xfree(method); -} - -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) { - error("userauth_banner: open %s failed: %s", - options.banner, strerror(errno)); - return; + if (authenticated == 1) { + authmsg = "Accepted"; + } else if (authenticated == 0) { + authmsg = "Failed"; + } else { + authmsg = "Postponed"; } - 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; -} + authlog("%s %s for %.200s from %.200s port %d ssh2", + authmsg, + method, + pw && pw->pw_uid == 0 ? "ROOT" : user, + get_remote_ipaddr(), + get_remote_port()); -void -userauth_reply(Authctxt *authctxt, int authenticated) -{ - char *methods; - /* XXX todo: check if multiple auth methods are needed */ if (authenticated == 1) { /* turn off userauth */ @@ -282,148 +209,99 @@ packet_send(); packet_write_wait(); /* now we can break out */ - authctxt->success = 1; - } else { - if (authctxt->failures++ > AUTH_FAIL_MAX) - packet_disconnect(AUTH_FAIL_MSG, authctxt->user); - methods = authmethods_get(); + userauth_success = 1; + } else if (authenticated == 0) { packet_start(SSH2_MSG_USERAUTH_FAILURE); - packet_put_cstring(methods); - packet_put_char(0); /* XXX partial success, unused */ + packet_put_cstring("publickey,password"); /* XXX dynamic */ + packet_put_char(0); /* XXX partial success, unused */ packet_send(); packet_write_wait(); - xfree(methods); } + + xfree(service); + xfree(user); + xfree(method); } int -userauth_none(Authctxt *authctxt) +ssh2_auth_none(struct passwd *pw) { - /* disable method "none", only allowed one time */ - Authmethod *m = authmethod_lookup("none"); - if (m != NULL) - m->enabled = NULL; packet_done(); - userauth_banner(); - return authctxt->valid ? auth_password(authctxt->pw, "") : 0; + return auth_password(pw, ""); } - int -userauth_passwd(Authctxt *authctxt) +ssh2_auth_password(struct passwd *pw) { char *password; int authenticated = 0; int change; - u_int len; + unsigned 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) + if (options.password_authentication && + auth_password(pw, password) == 1) authenticated = 1; memset(password, 0, len); xfree(password); return authenticated; } - int -userauth_kbdint(Authctxt *authctxt) +ssh2_auth_pubkey(struct passwd *pw, char *service) { - int authenticated = 0; - char *lang = NULL; - char *devs = NULL; - - lang = packet_get_string(NULL); - devs = packet_get_string(NULL); - packet_done(); - - debug("keyboard-interactive language %s devs %s", lang, devs); - - if (options.challenge_reponse_authentication) - authenticated = auth2_challenge(authctxt, devs); - - xfree(lang); - xfree(devs); - return authenticated; -} - -int -userauth_pubkey(Authctxt *authctxt) -{ Buffer b; Key *key; char *pkalg, *pkblob, *sig; - u_int alen, blen, slen; - int have_sig, pktype; + unsigned int alen, blen, slen; + int have_sig; int authenticated = 0; - if (!authctxt->valid) { - debug2("userauth_pubkey: disabled because of invalid user"); + if (options.dsa_authentication == 0) { + debug("pubkey auth disabled"); 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); + pkalg = packet_get_string(&alen); + if (strcmp(pkalg, KEX_DSS) != 0) { xfree(pkalg); - xfree(pkblob); + log("bad pkalg %s", pkalg); /*XXX*/ return 0; } - key = key_from_blob(pkblob, blen); + pkblob = packet_get_string(&blen); + key = dsa_key_from_blob(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); - } + buffer_append(&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, pw->pw_name); buffer_put_cstring(&b, - datafellows & SSH_BUG_PKSERVICE ? + datafellows & SSH_BUG_PUBKEYAUTH ? "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, key_ssh_name(key)); - } + service); + buffer_put_cstring(&b, "publickey"); + buffer_put_char(&b, have_sig); + buffer_put_cstring(&b, KEX_DSS); buffer_put_string(&b, pkblob, blen); -#ifdef DEBUG_PK +#ifdef DEBUG_DSS buffer_dump(&b); #endif /* test for correct signature */ - if (user_key_allowed(authctxt->pw, key) && - key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1) + if (user_dsa_key_allowed(pw, key) && + dsa_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(); - + debug("test key..."); + /* test whether pkalg/pkblob are acceptable */ /* XXX fake reply and always send PK_OK ? */ /* * XXX this allows testing whether a user is allowed @@ -432,101 +310,84 @@ * if a user is not allowed to login. is this an * issue? -markus */ - if (user_key_allowed(authctxt->pw, key)) { + if (user_dsa_key_allowed(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; + authenticated = -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; } -/* get current user */ +/* set and get current user */ struct passwd* auth_get_user(void) { - return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL; + return (authctxt != NULL && authctxt->valid) ? &authctxt->pw : NULL; } -#define DELIM "," - -char * -authmethods_get(void) +struct passwd* +auth_set_user(char *u, char *s) { - Authmethod *method = NULL; - u_int size = 0; - char *list; + struct passwd *pw, *copy; - for (method = authmethods; method->name != NULL; method++) { - if (strcmp(method->name, "none") == 0) - continue; - if (method->enabled != NULL && *(method->enabled) != 0) { - if (size != 0) - size += strlen(DELIM); - size += strlen(method->name); + if (authctxt == NULL) { + authctxt = xmalloc(sizeof(*authctxt)); + authctxt->valid = 0; + authctxt->user = xstrdup(u); + authctxt->service = xstrdup(s); + setproctitle("%s", u); + pw = getpwnam(u); + if (!pw || !allowed_user(pw)) { + log("auth_set_user: illegal user %s", u); + return NULL; } - } - 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); + copy = &authctxt->pw; + 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_dir = xstrdup(pw->pw_dir); + copy->pw_shell = xstrdup(pw->pw_shell); + authctxt->valid = 1; + } else { + if (strcmp(u, authctxt->user) != 0 || + strcmp(s, authctxt->service) != 0) { + log("auth_set_user: missmatch: (%s,%s)!=(%s,%s)", + u, s, authctxt->user, authctxt->service); + return NULL; } } - return list; + return auth_get_user(); } -Authmethod * -authmethod_lookup(const char *name) -{ - Authmethod *method = NULL; - 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"); - return NULL; -} - /* return 1 if user allows given key */ int -user_key_allowed(struct passwd *pw, Key *key) +user_dsa_key_allowed(struct passwd *pw, Key *key) { - char line[8192], file[MAXPATHLEN]; + char line[8192], file[1024]; int found_key = 0; + unsigned int bits = -1; FILE *f; - u_long linenum = 0; + unsigned long linenum = 0; struct stat st; Key *found; - if (pw == NULL) - return 0; - /* Temporarily use the user's uid. */ temporarily_use_uid(pw->pw_uid); /* The authorized keys. */ snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir, - _PATH_SSH_USER_PERMITTED_KEYS2); + SSH_USER_PERMITTED_KEYS2); /* Fail quietly if file does not exist */ if (stat(file, &st) < 0) { @@ -548,16 +409,14 @@ 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); + snprintf(buf, sizeof buf, "DSA authentication refused for %.100s: " + "bad ownership or modes for '%s'.", pw->pw_name, file); fail = 1; } else { - /* Check path to _PATH_SSH_USER_PERMITTED_KEYS */ + /* Check path to SSH_USER_PERMITTED_KEYS */ int i; static const char *check[] = { - "", _PATH_SSH_USER_DIR, NULL + "", SSH_USER_DIR, NULL }; for (i = 0; check[i]; i++) { snprintf(line, sizeof line, "%.500s/%.100s", @@ -566,55 +425,36 @@ (st.st_uid != 0 && st.st_uid != pw->pw_uid) || (st.st_mode & 022) != 0) { snprintf(buf, sizeof buf, - "%s authentication refused for %.100s: " + "DSA authentication refused for %.100s: " "bad ownership or modes for '%s'.", - key_type(key), pw->pw_name, line); + pw->pw_name, line); fail = 1; break; } } } if (fail) { + log(buf); fclose(f); - log("%s", buf); restore_uid(); return 0; } } found_key = 0; - found = key_new(key->type); + found = key_new(KEY_DSA); while (fgets(line, sizeof(line), f)) { - char *cp, *options = NULL; + char *cp; 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) { + bits = key_read(found, &cp); + if (bits == 0) + continue; + if (key_equal(found, key)) { found_key = 1; debug("matching key found: file %s, line %ld", file, linenum); @@ -624,7 +464,5 @@ restore_uid(); fclose(f); key_free(found); - if (!found_key) - debug2("key not found"); return found_key; }