xrdp/rdp/rdp_lic.c

/**
 * xrdp: A Remote Desktop Protocol server.
 *
 * Copyright (C) Jay Sorg 2004-2013
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * licence
 */

#include "rdp.h"

/*****************************************************************************/
struct rdp_lic *APP_CC
rdp_lic_create(struct rdp_sec *owner)
{
    struct rdp_lic *self;

    self = (struct rdp_lic *)g_malloc(sizeof(struct rdp_lic), 1);
    self->sec_layer = owner;
    return self;
}

/*****************************************************************************/
void APP_CC
rdp_lic_delete(struct rdp_lic *self)
{
    if (self == 0)
    {
        return;
    }

    g_free(self);
}

/*****************************************************************************/
/* Generate a session key and RC4 keys, given client and server randoms */
static void APP_CC
rdp_lic_generate_keys(struct rdp_lic *self, char *client_random,
                      char *server_random, char *pre_master_secret)
{
    char master_secret[48];
    char key_block[48];

    /* Generate master secret and then key material */
    rdp_sec_hash_48(master_secret, pre_master_secret, client_random,
                    server_random, 65);
    rdp_sec_hash_48(key_block, master_secret, server_random,
                    client_random, 65);
    /* Store first 16 bytes of session key as MAC secret */
    g_memcpy(self->licence_sign_key, key_block, 16);
    /* Generate RC4 key from next 16 bytes */
    rdp_sec_hash_16(self->licence_key, key_block + 16, client_random,
                    server_random);
}

/*****************************************************************************/
static void APP_CC
rdp_lic_generate_hwid(struct rdp_lic *self, char *hwid)
{
    rdp_sec_buf_out_uint32(hwid, 2);
    g_strncpy(hwid + 4, self->sec_layer->rdp_layer->mod->hostname,
              LICENCE_HWID_SIZE - 4);
}

/*****************************************************************************/
/* Present an existing licence to the server */
static void APP_CC
rdp_lic_present(struct rdp_lic *self, char *client_random, char *rsa_data,
                char *licence_data, int licence_size, char *hwid,
                char *signature)
{
    int sec_flags;
    int length;
    struct stream *s;

    sec_flags = SEC_LICENCE_NEG;
    length = 16 + SEC_RANDOM_SIZE + SEC_MODULUS_SIZE + SEC_PADDING_SIZE +
             licence_size + LICENCE_HWID_SIZE + LICENCE_SIGNATURE_SIZE;
    make_stream(s);
    init_stream(s, 8192);
    rdp_sec_init(self->sec_layer, s, sec_flags);
    out_uint8(s, LICENCE_TAG_PRESENT);
    out_uint8(s, 2); /* version */
    out_uint16_le(s, length);
    out_uint32_le(s, 1);
    out_uint16_le(s, 0);
    out_uint16_le(s, 0x0201);
    out_uint8p(s, client_random, SEC_RANDOM_SIZE);
    out_uint16_le(s, 0);
    out_uint16_le(s, (SEC_MODULUS_SIZE + SEC_PADDING_SIZE));
    out_uint8p(s, rsa_data, SEC_MODULUS_SIZE);
    out_uint8s(s, SEC_PADDING_SIZE);
    out_uint16_le(s, 1);
    out_uint16_le(s, licence_size);
    out_uint8p(s, licence_data, licence_size);
    out_uint16_le(s, 1);
    out_uint16_le(s, LICENCE_HWID_SIZE);
    out_uint8p(s, hwid, LICENCE_HWID_SIZE);
    out_uint8p(s, signature, LICENCE_SIGNATURE_SIZE);
    s_mark_end(s);
    rdp_sec_send(self->sec_layer, s, sec_flags);
    free_stream(s);
}

/*****************************************************************************/
/* Send a licence request packet */
static void APP_CC
rdp_lic_send_request(struct rdp_lic *self, char *client_random,
                     char *rsa_data, char *user, char *host)
{
    int sec_flags;
    int userlen;
    int hostlen;
    int length;
    struct stream *s;

    sec_flags = SEC_LICENCE_NEG;
    userlen = g_strlen(user) + 1;
    hostlen = g_strlen(host) + 1;
    length = 128 + userlen + hostlen;
    make_stream(s);
    init_stream(s, 8192);
    rdp_sec_init(self->sec_layer, s, sec_flags);
    out_uint8(s, LICENCE_TAG_REQUEST);
    out_uint8(s, 2); /* version */
    out_uint16_le(s, length);
    out_uint32_le(s, 1);
    out_uint16_le(s, 0);
    out_uint16_le(s, 0xff01);
    out_uint8p(s, client_random, SEC_RANDOM_SIZE);
    out_uint16_le(s, 0);
    out_uint16_le(s, (SEC_MODULUS_SIZE + SEC_PADDING_SIZE));
    out_uint8p(s, rsa_data, SEC_MODULUS_SIZE);
    out_uint8s(s, SEC_PADDING_SIZE);
    out_uint16_le(s, LICENCE_TAG_USER);
    out_uint16_le(s, userlen);
    out_uint8p(s, user, userlen);
    out_uint16_le(s, LICENCE_TAG_HOST);
    out_uint16_le(s, hostlen);
    out_uint8p(s, host, hostlen);
    s_mark_end(s);
    rdp_sec_send(self->sec_layer, s, sec_flags);
    free_stream(s);
}

/*****************************************************************************/
/* Process a licence demand packet */
static void APP_CC
rdp_lic_process_demand(struct rdp_lic *self, struct stream *s)
{
    char null_data[SEC_MODULUS_SIZE];
    char *server_random;
    char signature[LICENCE_SIGNATURE_SIZE];
    char hwid[LICENCE_HWID_SIZE];
    char *licence_data;
    int licence_size;
    void *crypt_key;

    licence_data = 0;
    /* Retrieve the server random from the incoming packet */
    in_uint8p(s, server_random, SEC_RANDOM_SIZE);
    /* We currently use null client keys. This is a bit naughty but, hey,
       the security of licence negotiation isn't exactly paramount. */
    g_memset(null_data, 0, sizeof(null_data));
    rdp_lic_generate_keys(self, null_data, server_random, null_data);

#if 0
    licence_size = 0; /* todo load_licence(&licence_data); */

    if (licence_size > 0)
    {
        /* Generate a signature for the HWID buffer */
        rdp_lic_generate_hwid(self, hwid);
        rdp_sec_sign(signature, 16, self->licence_sign_key, 16,
                     hwid, sizeof(hwid));
        /* Now encrypt the HWID */
        crypt_key = ssl_rc4_info_create();
        ssl_rc4_set_key(crypt_key, self->licence_key, 16);
        ssl_rc4_crypt(crypt_key, hwid, sizeof(hwid));
        ssl_rc4_info_delete(crypt_key);
        rdp_lic_present(self, null_data, null_data, licence_data,
                        licence_size, hwid, signature);
        g_free(licence_data);
        return;
    }
#endif

    rdp_lic_send_request(self, null_data, null_data,
                         self->sec_layer->rdp_layer->mod->username,
                         self->sec_layer->rdp_layer->mod->hostname);
}

/*****************************************************************************/
/* Send an authentication response packet */
static void APP_CC
rdp_lic_send_authresp(struct rdp_lic *self, char *token, char *crypt_hwid,
                      char *signature)
{
    int sec_flags;
    int length;
    struct stream *s;

    sec_flags = SEC_LICENCE_NEG;
    length = 58;
    make_stream(s);
    init_stream(s, 8192);
    rdp_sec_init(self->sec_layer, s, sec_flags);
    out_uint8(s, LICENCE_TAG_AUTHRESP);
    out_uint8(s, 2); /* version */
    out_uint16_le(s, length);
    out_uint16_le(s, 1);
    out_uint16_le(s, LICENCE_TOKEN_SIZE);
    out_uint8p(s, token, LICENCE_TOKEN_SIZE);
    out_uint16_le(s, 1);
    out_uint16_le(s, LICENCE_HWID_SIZE);
    out_uint8p(s, crypt_hwid, LICENCE_HWID_SIZE);
    out_uint8p(s, signature, LICENCE_SIGNATURE_SIZE);
    s_mark_end(s);
    rdp_sec_send(self->sec_layer, s, sec_flags);
    free_stream(s);
}

/*****************************************************************************/
/* Parse an authentication request packet */
/* returns boolean */
static int APP_CC
rdp_lic_parse_authreq(struct rdp_lic *self, struct stream *s,
                      char **token, char **signature)
{
    int tokenlen;

    in_uint8s(s, 6); /* unknown: f8 3d 15 00 04 f6 */
    in_uint16_le(s, tokenlen);

    if (tokenlen != LICENCE_TOKEN_SIZE)
    {
        /* error("token len %d\n", tokenlen); */
        return 0;
    }

    in_uint8p(s, *token, tokenlen);
    in_uint8p(s, *signature, LICENCE_SIGNATURE_SIZE);
    return s_check_end(s);
}

/*****************************************************************************/
/* Process an authentication request packet */
static void APP_CC
rdp_lic_process_authreq(struct rdp_lic *self, struct stream *s)
{
    char *in_token;
    char *in_sig;
    char out_token[LICENCE_TOKEN_SIZE];
    char decrypt_token[LICENCE_TOKEN_SIZE];
    char hwid[LICENCE_HWID_SIZE];
    char crypt_hwid[LICENCE_HWID_SIZE];
    char sealed_buffer[LICENCE_TOKEN_SIZE + LICENCE_HWID_SIZE];
    char out_sig[LICENCE_SIGNATURE_SIZE];
    void *crypt_key;

    in_token = 0;
    in_sig = 0;
    /* Parse incoming packet and save the encrypted token */
    rdp_lic_parse_authreq(self, s, &in_token, &in_sig);
    g_memcpy(out_token, in_token, LICENCE_TOKEN_SIZE);
    /* Decrypt the token. It should read TEST in Unicode. */
    crypt_key = ssl_rc4_info_create();
    ssl_rc4_set_key(crypt_key, self->licence_key, 16);
    g_memcpy(decrypt_token, in_token, LICENCE_TOKEN_SIZE);
    ssl_rc4_crypt(crypt_key, decrypt_token, LICENCE_TOKEN_SIZE);
    /* Generate a signature for a buffer of token and HWID */
    rdp_lic_generate_hwid(self, hwid);
    g_memcpy(sealed_buffer, decrypt_token, LICENCE_TOKEN_SIZE);
    g_memcpy(sealed_buffer + LICENCE_TOKEN_SIZE, hwid, LICENCE_HWID_SIZE);
    rdp_sec_sign(out_sig, 16, self->licence_sign_key, 16, sealed_buffer,
                 sizeof(sealed_buffer));
    /* Now encrypt the HWID */
    ssl_rc4_set_key(crypt_key, self->licence_key, 16);
    g_memcpy(crypt_hwid, hwid, LICENCE_HWID_SIZE);
    ssl_rc4_crypt(crypt_key, crypt_hwid, LICENCE_HWID_SIZE);
    rdp_lic_send_authresp(self, out_token, crypt_hwid, out_sig);
    ssl_rc4_info_delete(crypt_key);
}

/*****************************************************************************/
/* Process an licence issue packet */
static void APP_CC
rdp_lic_process_issue(struct rdp_lic *self, struct stream *s)
{
    void *crypt_key;
    int length;
    int check;
    int i;

    in_uint8s(s, 2); /* 3d 45 - unknown */
    in_uint16_le(s, length);

    if (!s_check_rem(s, length))
    {
        return;
    }

    crypt_key = ssl_rc4_info_create();
    ssl_rc4_set_key(crypt_key, self->licence_key, 16);
    ssl_rc4_crypt(crypt_key, s->p, length);
    ssl_rc4_info_delete(crypt_key);
    in_uint16_le(s, check);

    if (check != 0)
    {
        return;
    }

    self->licence_issued = 1;
    in_uint8s(s, 2); /* pad */
    /* advance to fourth string */
    length = 0;

    for (i = 0; i < 4; i++)
    {
        in_uint8s(s, length);
        in_uint32_le(s, length);

        if (!s_check_rem(s, length))
        {
            return;
        }
    }

    /* todo save_licence(s->p, length); */
}

/******************************************************************************/
/* Process a licence packet */
void APP_CC
rdp_lic_process(struct rdp_lic *self, struct stream *s)
{
    int tag;

    in_uint8(s, tag);
    in_uint8s(s, 3); /* version, length */

    switch (tag)
    {
        case LICENCE_TAG_DEMAND:
            rdp_lic_process_demand(self, s);
            break;
        case LICENCE_TAG_AUTHREQ:
            rdp_lic_process_authreq(self, s);
            break;
        case LICENCE_TAG_ISSUE:
            rdp_lic_process_issue(self, s);
            break;
        case LICENCE_TAG_REISSUE:
        case LICENCE_TAG_RESULT:
            break;
        default:
            break;
            /* todo unimpl("licence tag 0x%x\n", tag); */
    }
}