qemu/ui/vnc-ws.c
Daniel P. Berrange 8e9b0d24fb ui: convert VNC websockets to use crypto APIs
Remove the direct use of gnutls for hash processing in the
websockets code, in favour of using the crypto APIs. This
allows the websockets code to be built unconditionally
removing countless conditional checks from the VNC code.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1435770638-25715-9-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-07-08 13:11:01 +02:00

382 lines
12 KiB
C

/*
* QEMU VNC display driver: Websockets support
*
* Copyright (C) 2010 Joel Martin
* Copyright (C) 2012 Tim Hardeck
*
* This is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this software; if not, see <http://www.gnu.org/licenses/>.
*/
#include "vnc.h"
#include "qemu/main-loop.h"
#include "crypto/hash.h"
#ifdef CONFIG_VNC_TLS
#include "qemu/sockets.h"
static int vncws_start_tls_handshake(VncState *vs)
{
int ret = gnutls_handshake(vs->tls.session);
if (ret < 0) {
if (!gnutls_error_is_fatal(ret)) {
VNC_DEBUG("Handshake interrupted (blocking)\n");
if (!gnutls_record_get_direction(vs->tls.session)) {
qemu_set_fd_handler(vs->csock, vncws_tls_handshake_io,
NULL, vs);
} else {
qemu_set_fd_handler(vs->csock, NULL, vncws_tls_handshake_io,
vs);
}
return 0;
}
VNC_DEBUG("Handshake failed %s\n", gnutls_strerror(ret));
vnc_client_error(vs);
return -1;
}
if (vs->vd->tls.x509verify) {
if (vnc_tls_validate_certificate(vs) < 0) {
VNC_DEBUG("Client verification failed\n");
vnc_client_error(vs);
return -1;
} else {
VNC_DEBUG("Client verification passed\n");
}
}
VNC_DEBUG("Handshake done, switching to TLS data mode\n");
qemu_set_fd_handler(vs->csock, vncws_handshake_read, NULL, vs);
return 0;
}
void vncws_tls_handshake_io(void *opaque)
{
VncState *vs = (VncState *)opaque;
if (!vs->tls.session) {
VNC_DEBUG("TLS Websocket setup\n");
if (vnc_tls_client_setup(vs, vs->vd->tls.x509cert != NULL) < 0) {
return;
}
}
VNC_DEBUG("Handshake IO continue\n");
vncws_start_tls_handshake(vs);
}
#endif /* CONFIG_VNC_TLS */
void vncws_handshake_read(void *opaque)
{
VncState *vs = opaque;
uint8_t *handshake_end;
long ret;
/* Typical HTTP headers from novnc are 512 bytes, so limiting
* total header size to 4096 is easily enough. */
size_t want = 4096 - vs->ws_input.offset;
buffer_reserve(&vs->ws_input, want);
ret = vnc_client_read_buf(vs, buffer_end(&vs->ws_input), want);
if (!ret) {
if (vs->csock == -1) {
vnc_disconnect_finish(vs);
}
return;
}
vs->ws_input.offset += ret;
handshake_end = (uint8_t *)g_strstr_len((char *)vs->ws_input.buffer,
vs->ws_input.offset, WS_HANDSHAKE_END);
if (handshake_end) {
qemu_set_fd_handler(vs->csock, vnc_client_read, NULL, vs);
vncws_process_handshake(vs, vs->ws_input.buffer, vs->ws_input.offset);
buffer_advance(&vs->ws_input, handshake_end - vs->ws_input.buffer +
strlen(WS_HANDSHAKE_END));
} else if (vs->ws_input.offset >= 4096) {
VNC_DEBUG("End of headers not found in first 4096 bytes\n");
vnc_client_error(vs);
}
}
long vnc_client_read_ws(VncState *vs)
{
int ret, err;
uint8_t *payload;
size_t payload_size, header_size;
VNC_DEBUG("Read websocket %p size %zd offset %zd\n", vs->ws_input.buffer,
vs->ws_input.capacity, vs->ws_input.offset);
buffer_reserve(&vs->ws_input, 4096);
ret = vnc_client_read_buf(vs, buffer_end(&vs->ws_input), 4096);
if (!ret) {
return 0;
}
vs->ws_input.offset += ret;
ret = 0;
/* consume as much of ws_input buffer as possible */
do {
if (vs->ws_payload_remain == 0) {
err = vncws_decode_frame_header(&vs->ws_input,
&header_size,
&vs->ws_payload_remain,
&vs->ws_payload_mask);
if (err <= 0) {
return err;
}
buffer_advance(&vs->ws_input, header_size);
}
if (vs->ws_payload_remain != 0) {
err = vncws_decode_frame_payload(&vs->ws_input,
&vs->ws_payload_remain,
&vs->ws_payload_mask,
&payload,
&payload_size);
if (err < 0) {
return err;
}
if (err == 0) {
return ret;
}
ret += err;
buffer_reserve(&vs->input, payload_size);
buffer_append(&vs->input, payload, payload_size);
buffer_advance(&vs->ws_input, payload_size);
}
} while (vs->ws_input.offset > 0);
return ret;
}
long vnc_client_write_ws(VncState *vs)
{
long ret;
VNC_DEBUG("Write WS: Pending output %p size %zd offset %zd\n",
vs->output.buffer, vs->output.capacity, vs->output.offset);
vncws_encode_frame(&vs->ws_output, vs->output.buffer, vs->output.offset);
buffer_reset(&vs->output);
ret = vnc_client_write_buf(vs, vs->ws_output.buffer, vs->ws_output.offset);
if (!ret) {
return 0;
}
buffer_advance(&vs->ws_output, ret);
if (vs->ws_output.offset == 0) {
qemu_set_fd_handler(vs->csock, vnc_client_read, NULL, vs);
}
return ret;
}
static char *vncws_extract_handshake_entry(const char *handshake,
size_t handshake_len, const char *name)
{
char *begin, *end, *ret = NULL;
char *line = g_strdup_printf("%s%s: ", WS_HANDSHAKE_DELIM, name);
begin = g_strstr_len(handshake, handshake_len, line);
if (begin != NULL) {
begin += strlen(line);
end = g_strstr_len(begin, handshake_len - (begin - handshake),
WS_HANDSHAKE_DELIM);
if (end != NULL) {
ret = g_strndup(begin, end - begin);
}
}
g_free(line);
return ret;
}
static void vncws_send_handshake_response(VncState *vs, const char* key)
{
char combined_key[WS_CLIENT_KEY_LEN + WS_GUID_LEN + 1];
char *accept = NULL, *response = NULL;
Error *err = NULL;
g_strlcpy(combined_key, key, WS_CLIENT_KEY_LEN + 1);
g_strlcat(combined_key, WS_GUID, WS_CLIENT_KEY_LEN + WS_GUID_LEN + 1);
/* hash and encode it */
if (qcrypto_hash_base64(QCRYPTO_HASH_ALG_SHA1,
combined_key,
WS_CLIENT_KEY_LEN + WS_GUID_LEN,
&accept,
&err) < 0) {
VNC_DEBUG("Hashing Websocket combined key failed %s\n",
error_get_pretty(err));
error_free(err);
vnc_client_error(vs);
return;
}
response = g_strdup_printf(WS_HANDSHAKE, accept);
vnc_client_write_buf(vs, (const uint8_t *)response, strlen(response));
g_free(accept);
g_free(response);
vs->encode_ws = 1;
vnc_init_state(vs);
}
void vncws_process_handshake(VncState *vs, uint8_t *line, size_t size)
{
char *protocols = vncws_extract_handshake_entry((const char *)line, size,
"Sec-WebSocket-Protocol");
char *version = vncws_extract_handshake_entry((const char *)line, size,
"Sec-WebSocket-Version");
char *key = vncws_extract_handshake_entry((const char *)line, size,
"Sec-WebSocket-Key");
if (protocols && version && key
&& g_strrstr(protocols, "binary")
&& !strcmp(version, WS_SUPPORTED_VERSION)
&& strlen(key) == WS_CLIENT_KEY_LEN) {
vncws_send_handshake_response(vs, key);
} else {
VNC_DEBUG("Defective Websockets header or unsupported protocol\n");
vnc_client_error(vs);
}
g_free(protocols);
g_free(version);
g_free(key);
}
void vncws_encode_frame(Buffer *output, const void *payload,
const size_t payload_size)
{
size_t header_size = 0;
unsigned char opcode = WS_OPCODE_BINARY_FRAME;
union {
char buf[WS_HEAD_MAX_LEN];
WsHeader ws;
} header;
if (!payload_size) {
return;
}
header.ws.b0 = 0x80 | (opcode & 0x0f);
if (payload_size <= 125) {
header.ws.b1 = (uint8_t)payload_size;
header_size = 2;
} else if (payload_size < 65536) {
header.ws.b1 = 0x7e;
header.ws.u.s16.l16 = cpu_to_be16((uint16_t)payload_size);
header_size = 4;
} else {
header.ws.b1 = 0x7f;
header.ws.u.s64.l64 = cpu_to_be64(payload_size);
header_size = 10;
}
buffer_reserve(output, header_size + payload_size);
buffer_append(output, header.buf, header_size);
buffer_append(output, payload, payload_size);
}
int vncws_decode_frame_header(Buffer *input,
size_t *header_size,
size_t *payload_remain,
WsMask *payload_mask)
{
unsigned char opcode = 0, fin = 0, has_mask = 0;
size_t payload_len;
WsHeader *header = (WsHeader *)input->buffer;
if (input->offset < WS_HEAD_MIN_LEN + 4) {
/* header not complete */
return 0;
}
fin = (header->b0 & 0x80) >> 7;
opcode = header->b0 & 0x0f;
has_mask = (header->b1 & 0x80) >> 7;
payload_len = header->b1 & 0x7f;
if (opcode == WS_OPCODE_CLOSE) {
/* disconnect */
return -1;
}
/* Websocket frame sanity check:
* * Websocket fragmentation is not supported.
* * All websockets frames sent by a client have to be masked.
* * Only binary encoding is supported.
*/
if (!fin || !has_mask || opcode != WS_OPCODE_BINARY_FRAME) {
VNC_DEBUG("Received faulty/unsupported Websocket frame\n");
return -2;
}
if (payload_len < 126) {
*payload_remain = payload_len;
*header_size = 6;
*payload_mask = header->u.m;
} else if (payload_len == 126 && input->offset >= 8) {
*payload_remain = be16_to_cpu(header->u.s16.l16);
*header_size = 8;
*payload_mask = header->u.s16.m16;
} else if (payload_len == 127 && input->offset >= 14) {
*payload_remain = be64_to_cpu(header->u.s64.l64);
*header_size = 14;
*payload_mask = header->u.s64.m64;
} else {
/* header not complete */
return 0;
}
return 1;
}
int vncws_decode_frame_payload(Buffer *input,
size_t *payload_remain, WsMask *payload_mask,
uint8_t **payload, size_t *payload_size)
{
size_t i;
uint32_t *payload32;
*payload = input->buffer;
/* If we aren't at the end of the payload, then drop
* off the last bytes, so we're always multiple of 4
* for purpose of unmasking, except at end of payload
*/
if (input->offset < *payload_remain) {
*payload_size = input->offset - (input->offset % 4);
} else {
*payload_size = *payload_remain;
}
if (*payload_size == 0) {
return 0;
}
*payload_remain -= *payload_size;
/* unmask frame */
/* process 1 frame (32 bit op) */
payload32 = (uint32_t *)(*payload);
for (i = 0; i < *payload_size / 4; i++) {
payload32[i] ^= payload_mask->u;
}
/* process the remaining bytes (if any) */
for (i *= 4; i < *payload_size; i++) {
(*payload)[i] ^= payload_mask->c[i % 4];
}
return 1;
}