import openssh-5.2p1-gsskex-all-20090726.patch

1 files changed, 557 insertions, 0 deletions

diff --git a/auth2-jpake.c b/auth2-jpake.c
new file mode 100644
index 000000000..efe7ff2a3
--- /dev/null
+++ b/auth2-jpake.c
@@ -0,0 +1,557 @@
+/* $OpenBSD: auth2-jpake.c,v 1.2 2008/11/07 23:34:48 dtucker Exp $ */
+/*
+ * Copyright (c) 2008 Damien Miller.  All rights reserved.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * Server side of zero-knowledge password auth using J-PAKE protocol
+ * as described in:
+ *
+ * F. Hao, P. Ryan, "Password Authenticated Key Exchange by Juggling",
+ * 16th Workshop on Security Protocols, Cambridge, April 2008
+ *
+ * http://grouper.ieee.org/groups/1363/Research/contributions/hao-ryan-2008.pdf
+ */
+
+#ifdef JPAKE
+
+#include <sys/types.h>
+#include <sys/param.h>
+
+#include <pwd.h>
+#include <stdio.h>
+#include <string.h>
+#include <login_cap.h>
+
+#include <openssl/bn.h>
+#include <openssl/evp.h>
+
+#include "xmalloc.h"
+#include "ssh2.h"
+#include "key.h"
+#include "hostfile.h"
+#include "buffer.h"
+#include "auth.h"
+#include "packet.h"
+#include "dispatch.h"
+#include "log.h"
+#include "servconf.h"
+#include "auth-options.h"
+#include "canohost.h"
+#ifdef GSSAPI
+#include "ssh-gss.h"
+#endif
+#include "monitor_wrap.h"
+
+#include "jpake.h"
+
+/*
+ * XXX options->permit_empty_passwd (at the moment, they will be refused
+ * anyway because they will mismatch on fake salt.
+ */
+
+/* Dispatch handlers */
+static void input_userauth_jpake_client_step1(int, u_int32_t, void *);
+static void input_userauth_jpake_client_step2(int, u_int32_t, void *);
+static void input_userauth_jpake_client_confirm(int, u_int32_t, void *);
+
+static int auth2_jpake_start(Authctxt *);
+
+/* import */
+extern ServerOptions options;
+extern u_char *session_id2;
+extern u_int session_id2_len;
+
+/*
+ * Attempt J-PAKE authentication.
+ */
+static int
+userauth_jpake(Authctxt *authctxt)
+{
+        int authenticated = 0;
+
+        packet_check_eom();
+
+        debug("jpake-01@openssh.com requested");
+
+        if (authctxt->user != NULL) {
+                if (authctxt->jpake_ctx == NULL)
+                        authctxt->jpake_ctx = jpake_new();
+                if (options.zero_knowledge_password_authentication)
+                        authenticated = auth2_jpake_start(authctxt);
+        }
+
+        return authenticated;
+}
+
+Authmethod method_jpake = {
+        "jpake-01@openssh.com",
+        userauth_jpake,
+        &options.zero_knowledge_password_authentication
+};
+
+/* Clear context and callbacks */
+void
+auth2_jpake_stop(Authctxt *authctxt)
+{
+        /* unregister callbacks */
+        dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1, NULL);
+        dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2, NULL);
+        dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM, NULL);
+        if (authctxt->jpake_ctx != NULL) {
+                jpake_free(authctxt->jpake_ctx);
+                authctxt->jpake_ctx = NULL;
+        }
+}
+
+/* Returns 1 if 'c' is a valid crypt(3) salt character, 0 otherwise */
+static int
+valid_crypt_salt(int c)
+{
+        if (c >= 'A' && c <= 'Z')
+                return 1;
+        if (c >= 'a' && c <= 'z')
+                return 1;
+        if (c >= '.' && c <= '9')
+                return 1;
+        return 0;
+}
+
+/*
+ * Derive fake salt as H(username || first_private_host_key)
+ * This provides relatively stable fake salts for non-existent
+ * users and avoids the jpake method becoming an account validity
+ * oracle.
+ */
+static void
+derive_rawsalt(const char *username, u_char *rawsalt, u_int len)
+{
+        u_char *digest;
+        u_int digest_len;
+        Buffer b;
+        Key *k;
+
+        buffer_init(&b);
+        buffer_put_cstring(&b, username);
+        if ((k = get_hostkey_by_index(0)) == NULL ||
+            (k->flags & KEY_FLAG_EXT))
+                fatal("%s: no hostkeys", __func__);
+        switch (k->type) {
+        case KEY_RSA1:
+        case KEY_RSA:
+                if (k->rsa->p == NULL || k->rsa->q == NULL)
+                        fatal("%s: RSA key missing p and/or q", __func__);
+                buffer_put_bignum2(&b, k->rsa->p);
+                buffer_put_bignum2(&b, k->rsa->q);
+                break;
+        case KEY_DSA:
+                if (k->dsa->priv_key == NULL)
+                        fatal("%s: DSA key missing priv_key", __func__);
+                buffer_put_bignum2(&b, k->dsa->priv_key);
+                break;
+        default:
+                fatal("%s: unknown key type %d", __func__, k->type);
+        }
+        if (hash_buffer(buffer_ptr(&b), buffer_len(&b), EVP_sha256(),
+            &digest, &digest_len) != 0)
+                fatal("%s: hash_buffer", __func__);
+        buffer_free(&b);
+        if (len > digest_len)
+                fatal("%s: not enough bytes for rawsalt (want %u have %u)",
+                    __func__, len, digest_len);
+        memcpy(rawsalt, digest, len);
+        bzero(digest, digest_len);
+        xfree(digest);
+}
+
+/* ASCII an integer [0, 64) for inclusion in a password/salt */
+static char
+pw_encode64(u_int i64)
+{
+        const u_char e64[] =
+            "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+        return e64[i64 % 64];
+}
+
+/* Generate ASCII salt bytes for user */
+static char *
+makesalt(u_int want, const char *user)
+{
+        u_char rawsalt[32];
+        static char ret[33];
+        u_int i;
+
+        if (want > sizeof(ret) - 1)
+                fatal("%s: want %u", __func__, want);
+
+        derive_rawsalt(user, rawsalt, sizeof(rawsalt));
+        bzero(ret, sizeof(ret));
+        for (i = 0; i < want; i++)
+                ret[i] = pw_encode64(rawsalt[i]);
+        bzero(rawsalt, sizeof(rawsalt));
+
+        return ret;
+}
+
+/*
+ * Select the system's default password hashing scheme and generate
+ * a stable fake salt under it for use by a non-existent account.
+ * Prevents jpake method being used to infer the validity of accounts.
+ */
+static void
+fake_salt_and_scheme(Authctxt *authctxt, char **salt, char **scheme)
+{
+        char *rounds_s, *style;
+        long long rounds;
+        login_cap_t *lc;
+
+
+        if ((lc = login_getclass(authctxt->pw->pw_class)) == NULL &&
+            (lc = login_getclass(NULL)) == NULL)
+                fatal("%s: login_getclass failed", __func__);
+        style = login_getcapstr(lc, "localcipher", NULL, NULL);
+        if (style == NULL)
+                style = xstrdup("blowfish,6");
+        login_close(lc);
+        
+        if ((rounds_s = strchr(style, ',')) != NULL)
+                *rounds_s++ = '\0';
+        rounds = strtonum(rounds_s, 1, 1<<31, NULL);
+        
+        if (strcmp(style, "md5") == 0) {
+                xasprintf(salt, "$1$%s$", makesalt(8, authctxt->user));
+                *scheme = xstrdup("md5");
+        } else if (strcmp(style, "old") == 0) {
+                *salt = xstrdup(makesalt(2, authctxt->user));
+                *scheme = xstrdup("crypt");
+        } else if (strcmp(style, "newsalt") == 0) {
+                rounds = MAX(rounds, 7250);
+                rounds = MIN(rounds, (1<<24) - 1);
+                xasprintf(salt, "_%c%c%c%c%s",
+                    pw_encode64(rounds), pw_encode64(rounds >> 6),
+                    pw_encode64(rounds >> 12), pw_encode64(rounds >> 18),
+                    makesalt(4, authctxt->user));
+                *scheme = xstrdup("crypt-extended");
+        } else {
+                /* Default to blowfish */
+                rounds = MAX(rounds, 3);
+                rounds = MIN(rounds, 31);
+                xasprintf(salt, "$2a$%02lld$%s", rounds,
+                    makesalt(22, authctxt->user));
+                *scheme = xstrdup("bcrypt");
+        }
+        xfree(style);
+        debug3("%s: fake %s salt for user %s: %s",
+            __func__, *scheme, authctxt->user, *salt);
+}
+
+/*
+ * Fetch password hashing scheme, password salt and derive shared secret
+ * for user. If user does not exist, a fake but stable and user-unique
+ * salt will be returned.
+ */
+void
+auth2_jpake_get_pwdata(Authctxt *authctxt, BIGNUM **s,
+    char **hash_scheme, char **salt)
+{
+        char *cp;
+        u_char *secret;
+        u_int secret_len, salt_len;
+
+#ifdef JPAKE_DEBUG
+        debug3("%s: valid %d pw %.5s...", __func__,
+            authctxt->valid, authctxt->pw->pw_passwd);
+#endif
+
+        *salt = NULL;
+        *hash_scheme = NULL;
+        if (authctxt->valid) {
+                if (strncmp(authctxt->pw->pw_passwd, "$2$", 3) == 0 &&
+                    strlen(authctxt->pw->pw_passwd) > 28) {
+                        /*
+                         * old-variant bcrypt:
+                         *     "$2$", 2 digit rounds, "$", 22 bytes salt
+                         */
+                        salt_len = 3 + 2 + 1 + 22 + 1;
+                        *salt = xmalloc(salt_len);
+                        strlcpy(*salt, authctxt->pw->pw_passwd, salt_len);
+                        *hash_scheme = xstrdup("bcrypt");
+                } else if (strncmp(authctxt->pw->pw_passwd, "$2a$", 4) == 0 &&
+                    strlen(authctxt->pw->pw_passwd) > 29) {
+                        /*
+                         * current-variant bcrypt:
+                         *     "$2a$", 2 digit rounds, "$", 22 bytes salt
+                         */
+                        salt_len = 4 + 2 + 1 + 22 + 1;
+                        *salt = xmalloc(salt_len);
+                        strlcpy(*salt, authctxt->pw->pw_passwd, salt_len);
+                        *hash_scheme = xstrdup("bcrypt");
+                } else if (strncmp(authctxt->pw->pw_passwd, "$1$", 3) == 0 &&
+                    strlen(authctxt->pw->pw_passwd) > 5) {
+                        /*
+                         * md5crypt:
+                         *     "$1$", salt until "$"
+                         */
+                        cp = strchr(authctxt->pw->pw_passwd + 3, '$');
+                        if (cp != NULL) {
+                                salt_len = (cp - authctxt->pw->pw_passwd) + 1;
+                                *salt = xmalloc(salt_len);
+                                strlcpy(*salt, authctxt->pw->pw_passwd,
+                                    salt_len);
+                                *hash_scheme = xstrdup("md5crypt");
+                        }
+                } else if (strncmp(authctxt->pw->pw_passwd, "_", 1) == 0 &&
+                    strlen(authctxt->pw->pw_passwd) > 9) {
+                        /*
+                         * BSDI extended crypt:
+                         *     "_", 4 digits count, 4 chars salt
+                         */
+                        salt_len = 1 + 4 + 4 + 1;
+                        *salt = xmalloc(salt_len);
+                        strlcpy(*salt, authctxt->pw->pw_passwd, salt_len);
+                        *hash_scheme = xstrdup("crypt-extended");
+                } else if (strlen(authctxt->pw->pw_passwd) == 13  &&
+                    valid_crypt_salt(authctxt->pw->pw_passwd[0]) &&
+                    valid_crypt_salt(authctxt->pw->pw_passwd[1])) {
+                        /*
+                         * traditional crypt:
+                         *     2 chars salt
+                         */
+                        salt_len = 2 + 1;
+                        *salt = xmalloc(salt_len);
+                        strlcpy(*salt, authctxt->pw->pw_passwd, salt_len);
+                        *hash_scheme = xstrdup("crypt");
+                }
+                if (*salt == NULL) {
+                        debug("%s: unrecognised crypt scheme for user %s",
+                            __func__, authctxt->pw->pw_name);
+                }
+        }
+        if (*salt == NULL)
+                fake_salt_and_scheme(authctxt, salt, hash_scheme);
+
+        if (hash_buffer(authctxt->pw->pw_passwd,
+            strlen(authctxt->pw->pw_passwd), EVP_sha256(),
+            &secret, &secret_len) != 0)
+                fatal("%s: hash_buffer", __func__);
+        if ((*s = BN_bin2bn(secret, secret_len, NULL)) == NULL)
+                fatal("%s: BN_bin2bn (secret)", __func__);
+#ifdef JPAKE_DEBUG
+        debug3("%s: salt = %s (len %u)", __func__,
+            *salt, (u_int)strlen(*salt));
+        debug3("%s: scheme = %s", __func__, *hash_scheme);
+        JPAKE_DEBUG_BN((*s, "%s: s = ", __func__));
+#endif
+        bzero(secret, secret_len);
+        xfree(secret);
+}
+
+/*
+ * Being authentication attempt.
+ * Note, sets authctxt->postponed while in subprotocol
+ */
+static int
+auth2_jpake_start(Authctxt *authctxt)
+{
+        struct jpake_ctx *pctx = authctxt->jpake_ctx;
+        u_char *x3_proof, *x4_proof;
+        u_int x3_proof_len, x4_proof_len;
+        char *salt, *hash_scheme;
+
+        debug("%s: start", __func__);
+
+        PRIVSEP(jpake_step1(pctx->grp,
+            &pctx->server_id, &pctx->server_id_len,
+            &pctx->x3, &pctx->x4, &pctx->g_x3, &pctx->g_x4,
+            &x3_proof, &x3_proof_len,
+            &x4_proof, &x4_proof_len));
+
+        PRIVSEP(auth2_jpake_get_pwdata(authctxt, &pctx->s,
+            &hash_scheme, &salt));
+
+        if (!use_privsep)
+                JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
+
+        packet_start(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1);
+        packet_put_cstring(hash_scheme);
+        packet_put_cstring(salt);
+        packet_put_string(pctx->server_id, pctx->server_id_len);
+        packet_put_bignum2(pctx->g_x3);
+        packet_put_bignum2(pctx->g_x4);
+        packet_put_string(x3_proof, x3_proof_len);
+        packet_put_string(x4_proof, x4_proof_len);
+        packet_send();
+        packet_write_wait();
+
+        bzero(hash_scheme, strlen(hash_scheme));
+        bzero(salt, strlen(salt));
+        xfree(hash_scheme);
+        xfree(salt);
+        bzero(x3_proof, x3_proof_len);
+        bzero(x4_proof, x4_proof_len);
+        xfree(x3_proof);
+        xfree(x4_proof);
+
+        /* Expect step 1 packet from peer */
+        dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1,
+            input_userauth_jpake_client_step1);
+
+        authctxt->postponed = 1;
+        return 0;
+}
+
+/* ARGSUSED */
+static void
+input_userauth_jpake_client_step1(int type, u_int32_t seq, void *ctxt)
+{
+        Authctxt *authctxt = ctxt;
+        struct jpake_ctx *pctx = authctxt->jpake_ctx;
+        u_char *x1_proof, *x2_proof, *x4_s_proof;
+        u_int x1_proof_len, x2_proof_len, x4_s_proof_len;
+
+        /* Disable this message */
+        dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1, NULL);
+
+        /* Fetch step 1 values */
+        if ((pctx->g_x1 = BN_new()) == NULL ||
+            (pctx->g_x2 = BN_new()) == NULL)
+                fatal("%s: BN_new", __func__);
+        pctx->client_id = packet_get_string(&pctx->client_id_len);
+        packet_get_bignum2(pctx->g_x1);
+        packet_get_bignum2(pctx->g_x2);
+        x1_proof = packet_get_string(&x1_proof_len);
+        x2_proof = packet_get_string(&x2_proof_len);
+        packet_check_eom();
+
+        if (!use_privsep)
+                JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
+
+        PRIVSEP(jpake_step2(pctx->grp, pctx->s, pctx->g_x3,
+            pctx->g_x1, pctx->g_x2, pctx->x4,
+            pctx->client_id, pctx->client_id_len,
+            pctx->server_id, pctx->server_id_len,
+            x1_proof, x1_proof_len,
+            x2_proof, x2_proof_len,
+            &pctx->b,
+            &x4_s_proof, &x4_s_proof_len));
+
+        bzero(x1_proof, x1_proof_len);
+        bzero(x2_proof, x2_proof_len);
+        xfree(x1_proof);
+        xfree(x2_proof);
+
+        if (!use_privsep)
+                JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
+
+        /* Send values for step 2 */
+        packet_start(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2);
+        packet_put_bignum2(pctx->b);
+        packet_put_string(x4_s_proof, x4_s_proof_len);
+        packet_send();
+        packet_write_wait();
+
+        bzero(x4_s_proof, x4_s_proof_len);
+        xfree(x4_s_proof);
+
+        /* Expect step 2 packet from peer */
+        dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2,
+            input_userauth_jpake_client_step2);
+}
+
+/* ARGSUSED */
+static void
+input_userauth_jpake_client_step2(int type, u_int32_t seq, void *ctxt)
+{
+        Authctxt *authctxt = ctxt;
+        struct jpake_ctx *pctx = authctxt->jpake_ctx;
+        u_char *x2_s_proof;
+        u_int x2_s_proof_len;
+
+        /* Disable this message */
+        dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2, NULL);
+
+        if ((pctx->a = BN_new()) == NULL)
+                fatal("%s: BN_new", __func__);
+
+        /* Fetch step 2 values */
+        packet_get_bignum2(pctx->a);
+        x2_s_proof = packet_get_string(&x2_s_proof_len);
+        packet_check_eom();
+
+        if (!use_privsep)
+                JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
+
+        /* Derive shared key and calculate confirmation hash */
+        PRIVSEP(jpake_key_confirm(pctx->grp, pctx->s, pctx->a,
+            pctx->x4, pctx->g_x3, pctx->g_x4, pctx->g_x1, pctx->g_x2,
+            pctx->server_id, pctx->server_id_len,
+            pctx->client_id, pctx->client_id_len,
+            session_id2, session_id2_len,
+            x2_s_proof, x2_s_proof_len,
+            &pctx->k,
+            &pctx->h_k_sid_sessid, &pctx->h_k_sid_sessid_len));
+
+        bzero(x2_s_proof, x2_s_proof_len);
+        xfree(x2_s_proof);
+
+        if (!use_privsep)
+                JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
+
+        /* Send key confirmation proof */
+        packet_start(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM);
+        packet_put_string(pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len);
+        packet_send();
+        packet_write_wait();
+
+        /* Expect confirmation from peer */
+        dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM,
+            input_userauth_jpake_client_confirm);
+}
+
+/* ARGSUSED */
+static void
+input_userauth_jpake_client_confirm(int type, u_int32_t seq, void *ctxt)
+{
+        Authctxt *authctxt = ctxt;
+        struct jpake_ctx *pctx = authctxt->jpake_ctx;
+        int authenticated = 0;
+
+        /* Disable this message */
+        dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM, NULL);
+
+        pctx->h_k_cid_sessid = packet_get_string(&pctx->h_k_cid_sessid_len);
+        packet_check_eom();
+
+        if (!use_privsep)
+                JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
+
+        /* Verify expected confirmation hash */
+        if (PRIVSEP(jpake_check_confirm(pctx->k,
+            pctx->client_id, pctx->client_id_len,
+            session_id2, session_id2_len,
+            pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len)) == 1)
+                authenticated = authctxt->valid ? 1 : 0;
+        else
+                debug("%s: confirmation mismatch", __func__);
+                
+        /* done */
+        authctxt->postponed = 0;
+        jpake_free(authctxt->jpake_ctx);
+        authctxt->jpake_ctx = NULL;
+        userauth_finish(authctxt, authenticated, method_jpake.name);
+}
+
+#endif /* JPAKE */
+