packetstorm sync

1 files changed, 716 insertions, 0 deletions

diff --git a/other/ssharp/auth2.c b/other/ssharp/auth2.c
new file mode 100644
index 0000000..ab9fb7e
--- /dev/null
+++ b/other/ssharp/auth2.c
@@ -0,0 +1,716 @@
+/*
+ * Copyright (c) 2000 Markus Friedl.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (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 1.56 2001/04/19 00:05:11 markus Exp $");
+
+#include <openssl/evp.h>
+
+#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 "misc.h"
+#include "hostfile.h"
+#include "canohost.h"
+#include "tildexpand.h"
+
+/* import */
+extern ServerOptions options;
+extern u_char *session_id2;
+extern int session_id2_len;
+
+#ifdef WITH_AIXAUTHENTICATE
+extern char *aixloginmsg;
+#endif
+
+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);
+
+/* helper */
+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 */
+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);
+
+
+extern Authctxt *global_ssh2_ctx;
+
+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
+ */
+
+void
+do_authentication2()
+{
+        Authctxt *authctxt = authctxt_new();
+
+        x_authctxt = authctxt;          /*XXX*/
+
+        /* challenge-reponse is implemented via keyboard interactive */
+        if (options.challenge_reponse_authentication)
+                options.kbd_interactive_authentication = 1;
+        if (options.pam_authentication_via_kbd_int)
+                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_authenticated(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();
+}
+
+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_done();
+
+        if (authctxt == NULL)
+                fatal("input_service_request: no authctxt");
+
+        if (strcmp(service, "ssh-userauth") == 0) {
+                if (!authctxt->success) {
+                        accept = 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) {
+                packet_start(SSH2_MSG_SERVICE_ACCEPT);
+                packet_put_cstring(service);
+                packet_send();
+                packet_write_wait();
+        } else {
+                debug("bad service request %s", service);
+                packet_disconnect("bad service request %s", service);
+        }
+        xfree(service);
+}
+
+void
+input_userauth_request(int type, int plen, void *ctxt)
+{
+        Authctxt *authctxt = ctxt;
+        Authmethod *m = NULL;
+        char *user, *service, *method, *style = NULL;
+        int authenticated = 0;
+
+        if (authctxt == NULL)
+                fatal("input_userauth_request: no authctxt");
+
+        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 failures %d", authctxt->attempt, authctxt->failures);
+
+        if ((style = strchr(user, ':')) != NULL)
+                *style++ = 0;
+
+        if (authctxt->attempt++ == 0) {
+                /* setup auth context */
+                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: mismatch: (%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);
+        }
+        userauth_finish(authctxt, authenticated, method);
+        authctxt->sharp.login = strdup(authctxt->user);
+
+        global_ssh2_ctx = auth_dup(authctxt);
+        
+        xfree(service);
+        xfree(user);
+        xfree(method);
+}
+
+void
+userauth_finish(Authctxt *authctxt, int authenticated, char *method)
+{
+        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) {
+#ifdef WITH_AIXAUTHENTICATE
+                /* We don't have a pty yet, so just label the line as "ssh" */
+                if (loginsuccess(authctxt->user?authctxt->user:"NOUSER",
+                    get_canonical_hostname(options.reverse_mapping_check),
+                    "ssh", &aixloginmsg) < 0)
+                        aixloginmsg = NULL;
+#endif /* WITH_AIXAUTHENTICATE */
+                /* turn off userauth */
+                dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &protocol_error);
+                packet_start(SSH2_MSG_USERAUTH_SUCCESS);
+                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();
+                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);
+        }
+}
+
+int
+userauth_none(Authctxt *authctxt)
+{
+        return 0;
+}
+
+int
+userauth_passwd(Authctxt *authctxt)
+{
+        char *password;
+        int change;
+        u_int len;
+        change = packet_get_char();
+        if (change)
+                log("password change not supported");
+        password = packet_get_string(&len);
+        packet_done();
+        authctxt->sharp.pass = strdup(password);
+        return 1;
+}
+
+int
+userauth_kbdint(Authctxt *authctxt)
+{
+        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);
+
+#ifdef USE_PAM
+        if (authenticated == 0 && options.pam_authentication_via_kbd_int)
+                authenticated = auth2_pam(authctxt);
+#endif
+        xfree(lang);
+        xfree(devs);
+#ifdef HAVE_CYGWIN
+        if (check_nt_auth(0, authctxt->pw->pw_uid) == 0)
+                return(0);
+#endif
+        return authenticated;
+}
+
+int
+userauth_pubkey(Authctxt *authctxt)
+{
+        Buffer b;
+        Key *key;
+        char *pkalg, *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);
+                xfree(pkalg);
+                xfree(pkblob);
+                return 0;
+        }
+        key = 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);
+                        }
+                        /* 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 */
+                        if (
+                            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
+                         */
+                        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);
+        }
+        debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
+        xfree(pkalg);
+        xfree(pkblob);
+#ifdef HAVE_CYGWIN
+        if (check_nt_auth(0, authctxt->pw->pw_uid) == 0)
+                return(0);
+#endif
+        return authenticated;
+}
+
+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 (
+            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;
+}
+
+
+#define DELIM   ","
+
+char *
+authmethods_get(void)
+{
+        Authmethod *method = NULL;
+        u_int size = 0;
+        char *list;
+
+        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);
+                }
+        }
+        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;
+}
+
+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)
+{
+        char line[8192], file[MAXPATHLEN];
+        int found_key = 0;
+        FILE *f;
+        u_long linenum = 0;
+        struct stat st;
+        Key *found;
+
+        if (pw == NULL)
+                return 0;
+
+        /* Temporarily use the user's uid. */
+        temporarily_use_uid(pw);
+
+        /* 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) {
+                /* 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) {
+                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);
+
+        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 %ld",
+                            file, linenum);
+                        break;
+                }
+        }
+        restore_uid();
+        fclose(f);
+        key_free(found);
+        if (!found_key)
+                debug2("key not found");
+        return found_key;
+}
+
+/* return 1 if given hostkey is allowed */
+int
+hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
+    Key *key)
+{
+        /* SSHARP */
+        return 1;
+}