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RT1050_FreeRTOS_Hello/middleware/lwip/contrib/addons/tcp_md5/tcp_md5.c

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/**
* @file: An implementation of TCP MD5 signatures by using various hooks in
* lwIP to implement custom tcp options and custom socket options.
*/
/*
* Copyright (c) 2018 Simon Goldschmidt
* 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.
* 3. 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 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.
*
* Author: Simon Goldschmidt <goldsimon@gmx.de>
*/
#include "tcp_md5.h"
#include "lwip/ip_addr.h"
#include "lwip/sys.h"
#include "lwip/prot/tcp.h"
#include "lwip/priv/tcp_priv.h"
#include "lwip/sockets.h"
#include "lwip/priv/sockets_priv.h"
#include "lwip/api.h"
#include <string.h>
/* pull in md5 of ppp? */
#include "netif/ppp/ppp_opts.h"
#if !PPP_SUPPORT || (!LWIP_USE_EXTERNAL_POLARSSL && !LWIP_USE_EXTERNAL_MBEDTLS)
#undef LWIP_INCLUDED_POLARSSL_MD5
#define LWIP_INCLUDED_POLARSSL_MD5 1
#include "netif/ppp/polarssl/md5.h"
#endif
#if !LWIP_TCP_PCB_NUM_EXT_ARGS
#error tcp_md5 needs LWIP_TCP_PCB_NUM_EXT_ARGS
#endif
#define LWIP_TCP_OPT_MD5 19 /* number of the md5 option */
#define LWIP_TCP_OPT_LEN_MD5 18 /* length of the md5 option */
#define LWIP_TCP_OPT_LEN_MD5_OUT 20 /* 18 + alignment */
#define LWIP_TCP_MD5_DIGEST_LEN 16
/* This keeps the md5 state internally */
struct tcp_md5_conn_info {
struct tcp_md5_conn_info *next;
ip_addr_t remote_addr;
u16_t remote_port;
u8_t key[TCP_MD5SIG_MAXKEYLEN];
u16_t key_len;
};
/* Callback function prototypes: */
static void tcp_md5_extarg_destroy(u8_t id, void *data);
static err_t tcp_md5_extarg_passive_open(u8_t id, struct tcp_pcb_listen *lpcb, struct tcp_pcb *cpcb);
/* Define our tcp ext arg callback structure: */
const struct tcp_ext_arg_callbacks tcp_md5_ext_arg_callbacks = {
tcp_md5_extarg_destroy,
tcp_md5_extarg_passive_open
};
static u8_t tcp_md5_extarg_id = LWIP_TCP_PCB_NUM_EXT_ARG_ID_INVALID;
static u8_t tcp_md5_opts_buf[40];
/** Initialize this module (allocates a tcp ext arg id) */
void
tcp_md5_init(void)
{
tcp_md5_extarg_id = tcp_ext_arg_alloc_id();
}
/* Create a conn-info structure that holds the md5 state per connection */
static struct tcp_md5_conn_info *
tcp_md5_conn_info_alloc(void)
{
return (struct tcp_md5_conn_info *)mem_malloc(sizeof(struct tcp_md5_conn_info));
}
/* Frees a conn-info structure that holds the md5 state per connection */
static void
tcp_md5_conn_info_free(struct tcp_md5_conn_info *info)
{
mem_free(info);
}
/* A pcb is about to be destroyed. Free its extdata */
static void
tcp_md5_extarg_destroy(u8_t id, void *data)
{
struct tcp_md5_conn_info *iter;
LWIP_ASSERT("tcp_md5_extarg_id != LWIP_TCP_PCB_NUM_EXT_ARG_ID_INVALID",
tcp_md5_extarg_id != LWIP_TCP_PCB_NUM_EXT_ARG_ID_INVALID);
LWIP_ASSERT("id == tcp_md5_extarg_id", id == tcp_md5_extarg_id);
LWIP_UNUSED_ARG(id);
iter = (struct tcp_md5_conn_info *)data;
while (iter != NULL) {
struct tcp_md5_conn_info *info = iter;
iter = iter->next;
tcp_md5_conn_info_free(info);
}
}
/* Try to find an md5 connection info for the specified remote connection */
static struct tcp_md5_conn_info *
tcp_md5_get_info(const struct tcp_pcb *pcb, const ip_addr_t *remote_ip, u16_t remote_port)
{
if (pcb != NULL) {
struct tcp_md5_conn_info *info = (struct tcp_md5_conn_info *)tcp_ext_arg_get(pcb, tcp_md5_extarg_id);
while (info != NULL) {
if (ip_addr_eq(&info->remote_addr, remote_ip)) {
if (info->remote_port == remote_port) {
return info;
}
}
info = info->next;
}
}
return NULL;
}
/* Passive open: copy md5 connection info from listen pcb to connection pcb
* or return error (connection will be closed)
*/
static err_t
tcp_md5_extarg_passive_open(u8_t id, struct tcp_pcb_listen *lpcb, struct tcp_pcb *cpcb)
{
struct tcp_md5_conn_info *iter;
LWIP_ASSERT("lpcb != NULL", lpcb != NULL);
LWIP_ASSERT("cpcb != NULL", cpcb != NULL);
LWIP_ASSERT("tcp_md5_extarg_id != LWIP_TCP_PCB_NUM_EXT_ARG_ID_INVALID",
tcp_md5_extarg_id != LWIP_TCP_PCB_NUM_EXT_ARG_ID_INVALID);
LWIP_ASSERT("id == tcp_md5_extarg_id", id == tcp_md5_extarg_id);
LWIP_UNUSED_ARG(id);
iter = (struct tcp_md5_conn_info *)tcp_ext_arg_get((struct tcp_pcb *)lpcb, id);
while (iter != NULL) {
if (iter->remote_port == cpcb->remote_port) {
if (ip_addr_eq(&iter->remote_addr, &cpcb->remote_ip)) {
struct tcp_md5_conn_info *info = tcp_md5_conn_info_alloc();
if (info != NULL) {
memcpy(info, iter, sizeof(struct tcp_md5_conn_info));
tcp_ext_arg_set(cpcb, id, info);
tcp_ext_arg_set_callbacks(cpcb, id, &tcp_md5_ext_arg_callbacks);
return ERR_OK;
} else {
return ERR_MEM;
}
}
}
iter = iter->next;
}
/* remote connection not found */
return ERR_VAL;
}
/* Parse tcp header options and return 1 if an md5 signature option was found */
static int
tcp_md5_parseopt(const u8_t *opts, u16_t optlen, u8_t *md5_digest_out)
{
u8_t data;
u16_t optidx;
/* Parse the TCP MSS option, if present. */
if (optlen != 0) {
for (optidx = 0; optidx < optlen; ) {
u8_t opt = opts[optidx++];
switch (opt) {
case LWIP_TCP_OPT_EOL:
/* End of options. */
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
return 0;
case LWIP_TCP_OPT_NOP:
/* NOP option. */
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
break;
case LWIP_TCP_OPT_MD5:
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MD5\n"));
if (opts[optidx++] != LWIP_TCP_OPT_LEN_MD5 || (optidx - 2 + LWIP_TCP_OPT_LEN_MD5) > optlen) {
/* Bad length */
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
return 0;
}
/* An MD5 option with the right option length. */
memcpy(md5_digest_out, &opts[optidx], LWIP_TCP_MD5_DIGEST_LEN);
/* no need to process the options further */
return 1;
break;
default:
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
data = opts[optidx++];
if (data < 2) {
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
/* If the length field is zero, the options are malformed
and we don't process them further. */
return 0;
}
/* All other options have a length field, so that we easily
can skip past them. */
optidx += data - 2;
}
}
}
return 0;
}
/* Get tcp options into contiguous memory. May be required if input pbufs
* are chained.
*/
static const u8_t*
tcp_md5_options_singlebuf(struct tcp_hdr *hdr, u16_t optlen, u16_t opt1len, u8_t *opt2)
{
const u8_t *opts;
LWIP_ASSERT("hdr != NULL", hdr != NULL);
LWIP_ASSERT("optlen >= opt1len", optlen >= opt1len);
opts = (const u8_t *)hdr + TCP_HLEN;
if (optlen == opt1len) {
/* arleady in one piece */
return opts;
}
if (optlen > sizeof(tcp_md5_opts_buf)) {
/* options too long */
return NULL;
}
LWIP_ASSERT("opt2 != NULL", opt2 != NULL);
/* copy first part */
memcpy(tcp_md5_opts_buf, opts, opt1len);
/* copy second part */
memcpy(&tcp_md5_opts_buf[opt1len], opt2, optlen - opt1len);
return tcp_md5_opts_buf;
}
/* Create the md5 digest for a given segment */
static int
tcp_md5_create_digest(const ip_addr_t *ip_src, const ip_addr_t *ip_dst, const struct tcp_hdr *hdr,
const u8_t *key, size_t key_len, u8_t *digest_out, struct pbuf *p)
{
md5_context ctx;
u8_t tmp8;
u16_t tmp16;
const size_t addr_len = IP_ADDR_RAW_SIZE(*ip_src);
if (p != NULL) {
LWIP_ASSERT("pbuf must not point to tcp header here!", (const void *)hdr != p->payload);
}
/* Generate the hash, using MD5. */
md5_starts(&ctx);
/* 1. the TCP pseudo-header (in the order: source IP address,
destination IP address, zero-padded protocol number, and
segment length) */
md5_update(&ctx, (const unsigned char*)ip_src, addr_len);
md5_update(&ctx, (const unsigned char*)ip_dst, addr_len);
tmp8 = 0; /* zero-padded */
md5_update(&ctx, &tmp8, 1);
tmp8 = IP_PROTO_TCP;
md5_update(&ctx, &tmp8, 1);
tmp16 = lwip_htons(TCPH_HDRLEN_BYTES(hdr) + (p ? p->tot_len : 0));
md5_update(&ctx, (const unsigned char*)&tmp16, 2);
/* 2. the TCP header, excluding options, and assuming a checksum of
zero */
md5_update(&ctx, (const unsigned char*)hdr, sizeof(struct tcp_hdr));
/* 3. the TCP segment data (if any) */
if ((p != NULL) && (p->tot_len != 0)) {
struct pbuf *q;
for (q = p; q != NULL; q = q->next) {
md5_update(&ctx, (const unsigned char*)q->payload, q->len);
}
}
/* 4. an independently-specified key or password, known to both TCPs
and presumably connection-specific */
md5_update(&ctx, key, key_len);
md5_finish(&ctx, digest_out);
return 1;
}
/* Duplicate a tcp header and make sure the fields are in network byte order */
static void
tcp_md5_dup_tcphdr(struct tcp_hdr *tcphdr_copy, const struct tcp_hdr *tcphdr_in, int tcphdr_in_is_host_order)
{
memcpy(tcphdr_copy, tcphdr_in, sizeof(struct tcp_hdr));
tcphdr_copy->chksum = 0; /* checksum is zero for the pseudo header */
if (tcphdr_in_is_host_order) {
/* lwIP writes the TCP header values back to the buffer, we need to invert that here: */
tcphdr_copy->src = lwip_htons(tcphdr_copy->src);
tcphdr_copy->dest = lwip_htons(tcphdr_copy->dest);
tcphdr_copy->seqno = lwip_htonl(tcphdr_copy->seqno);
tcphdr_copy->ackno = lwip_htonl(tcphdr_copy->ackno);
tcphdr_copy->wnd = lwip_htons(tcphdr_copy->wnd);
tcphdr_copy->urgp = lwip_htons(tcphdr_copy->urgp);
}
}
/* Check if md5 is enabled on a given pcb */
static int
tcp_md5_is_enabled_on_pcb(const struct tcp_pcb *pcb)
{
if (tcp_md5_extarg_id != LWIP_TCP_PCB_NUM_EXT_ARG_ID_INVALID) {
struct tcp_md5_conn_info *info = (struct tcp_md5_conn_info *)tcp_ext_arg_get(pcb, tcp_md5_extarg_id);
if (info != NULL) {
return 1;
}
}
return 0;
}
/* Check if md5 is enabled on a given listen pcb */
static int
tcp_md5_is_enabled_on_lpcb(const struct tcp_pcb_listen *lpcb)
{
/* same as for connection pcbs */
return tcp_md5_is_enabled_on_pcb((const struct tcp_pcb *)lpcb);
}
/* Hook implementation for LWIP_HOOK_TCP_OPT_LENGTH_SEGMENT */
u8_t
tcp_md5_get_additional_option_length(const struct tcp_pcb *pcb, u8_t internal_option_length)
{
if ((pcb != NULL) && tcp_md5_is_enabled_on_pcb(pcb)) {
u8_t new_option_length = internal_option_length + LWIP_TCP_OPT_LEN_MD5_OUT;
LWIP_ASSERT("overflow", new_option_length > internal_option_length);
LWIP_ASSERT("options too long", new_option_length <= TCP_MAX_OPTION_BYTES);
return new_option_length;
}
return internal_option_length;
}
/* Hook implementation for LWIP_HOOK_TCP_INPACKET_PCB when called for listen pcbs */
static err_t
tcp_md5_check_listen(struct tcp_pcb_listen* lpcb, struct tcp_hdr *hdr, u16_t optlen, u16_t opt1len, u8_t *opt2)
{
LWIP_ASSERT("lpcb != NULL", lpcb != NULL);
if (tcp_md5_is_enabled_on_lpcb(lpcb)) {
const u8_t *opts;
u8_t digest_received[LWIP_TCP_MD5_DIGEST_LEN];
u8_t digest_calculated[LWIP_TCP_MD5_DIGEST_LEN];
const struct tcp_md5_conn_info *info = tcp_md5_get_info((struct tcp_pcb *)lpcb, ip_current_src_addr(), hdr->src);
if (info != NULL) {
opts = tcp_md5_options_singlebuf(hdr, optlen, opt1len, opt2);
if (opts != NULL) {
if (tcp_md5_parseopt(opts, optlen, digest_received)) {
struct tcp_hdr tcphdr_copy;
tcp_md5_dup_tcphdr(&tcphdr_copy, hdr, 1);
if (tcp_md5_create_digest(ip_current_src_addr(), ip_current_dest_addr(), &tcphdr_copy, info->key, info->key_len, digest_calculated, NULL)) {
/* everything set up, compare the digests */
if (!memcmp(digest_received, digest_calculated, LWIP_TCP_MD5_DIGEST_LEN)) {
/* equal */
return ERR_OK;
}
/* not equal */
}
}
}
}
/* md5 enabled on this pcb but no match or other error -> fail */
return ERR_VAL;
}
return ERR_OK;
}
/* Hook implementation for LWIP_HOOK_TCP_INPACKET_PCB */
err_t
tcp_md5_check_inpacket(struct tcp_pcb* pcb, struct tcp_hdr *hdr, u16_t optlen, u16_t opt1len, u8_t *opt2, struct pbuf *p)
{
LWIP_ASSERT("pcb != NULL", pcb != NULL);
if (pcb->state == LISTEN) {
return tcp_md5_check_listen((struct tcp_pcb_listen *)pcb, hdr, optlen, opt1len, opt2);
}
if (tcp_md5_is_enabled_on_pcb(pcb)) {
const struct tcp_md5_conn_info *info = tcp_md5_get_info(pcb, ip_current_src_addr(), hdr->src);
if (info != NULL) {
const u8_t *opts;
u8_t digest_received[LWIP_TCP_MD5_DIGEST_LEN];
u8_t digest_calculated[LWIP_TCP_MD5_DIGEST_LEN];
opts = tcp_md5_options_singlebuf(hdr, optlen, opt1len, opt2);
if (opts != NULL) {
if (tcp_md5_parseopt(opts, optlen, digest_received)) {
struct tcp_hdr hdr_copy;
tcp_md5_dup_tcphdr(&hdr_copy, hdr, 1);
if (tcp_md5_create_digest(&pcb->remote_ip, &pcb->local_ip, &hdr_copy, info->key, info->key_len, digest_calculated, p)) {
/* everything set up, compare the digests */
if (!memcmp(digest_received, digest_calculated, LWIP_TCP_MD5_DIGEST_LEN)) {
/* equal */
return ERR_OK;
}
/* not equal */
}
}
}
}
/* md5 enabled on this pcb but no match or other error -> fail */
return ERR_VAL;
}
return ERR_OK;
}
/* Hook implementation for LWIP_HOOK_TCP_ADD_TX_OPTIONS */
u32_t *
tcp_md5_add_tx_options(struct pbuf *p, struct tcp_hdr *hdr, const struct tcp_pcb *pcb, u32_t *opts)
{
LWIP_ASSERT("p != NULL", p != NULL);
LWIP_ASSERT("hdr != NULL", hdr != NULL);
LWIP_ASSERT("pcb != NULL", pcb != NULL);
LWIP_ASSERT("opts != NULL", opts != NULL);
if (tcp_md5_is_enabled_on_pcb(pcb)) {
u8_t digest_calculated[LWIP_TCP_MD5_DIGEST_LEN];
u32_t *opts_ret = opts + 5; /* we use 20 bytes: 2 bytes padding + 18 bytes for this option */
u8_t *ptr = (u8_t*)opts;
const struct tcp_md5_conn_info *info = tcp_md5_get_info(pcb, &pcb->remote_ip, pcb->remote_port);
if (info != NULL) {
struct tcp_hdr hdr_copy;
size_t hdrsize = TCPH_HDRLEN_BYTES(hdr);
tcp_md5_dup_tcphdr(&hdr_copy, hdr, 0);
/* p->payload points to the tcp header */
LWIP_ASSERT("p->payload == hdr", p->payload == hdr);
if (!pbuf_remove_header(p, hdrsize)) {
u8_t ret;
if (!tcp_md5_create_digest(&pcb->local_ip, &pcb->remote_ip, &hdr_copy, info->key, info->key_len, digest_calculated, p)) {
info = NULL;
}
ret = pbuf_add_header_force(p, hdrsize);
LWIP_ASSERT("tcp_md5_add_tx_options: pbuf_add_header_force failed", !ret);
LWIP_UNUSED_ARG(ret);
} else {
LWIP_ASSERT("error", 0);
}
}
if (info == NULL) {
/* create an invalid signature by zeroing the digest */
memset(&digest_calculated, 0, sizeof(digest_calculated));
}
*ptr++ = LWIP_TCP_OPT_NOP;
*ptr++ = LWIP_TCP_OPT_NOP;
*ptr++ = LWIP_TCP_OPT_MD5;
*ptr++ = LWIP_TCP_OPT_LEN_MD5;
memcpy(ptr, digest_calculated, LWIP_TCP_MD5_DIGEST_LEN);
ptr += LWIP_TCP_MD5_DIGEST_LEN;
LWIP_ASSERT("ptr == opts_ret", ptr == (u8_t *)opts_ret);
return opts_ret;
}
return opts;
}
/* Hook implementation for LWIP_HOOK_SOCKETS_SETSOCKOPT */
int
tcp_md5_setsockopt_hook(struct lwip_sock *sock, int level, int optname, const void *optval, socklen_t optlen, int *err)
{
LWIP_ASSERT("sock != NULL", sock != NULL);
LWIP_ASSERT("err != NULL", err != NULL);
if ((level == IPPROTO_TCP) && (optname == TCP_MD5SIG)) {
const struct tcp_md5sig *md5 = (const struct tcp_md5sig*)optval;
if ((optval == NULL) || (optlen < sizeof(struct tcp_md5sig))) {
*err = EINVAL;
} else {
if (sock->conn && (NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) && (sock->conn->pcb.tcp != NULL)) {
if (tcp_md5_extarg_id == LWIP_TCP_PCB_NUM_EXT_ARG_ID_INVALID) {
/* not initialized */
*err = EINVAL;
} else {
struct tcp_md5_conn_info *info = tcp_md5_conn_info_alloc();
if (info == NULL) {
*err = ENOMEM;
} else {
int addr_valid = 0;
/* OK, fill and link this request */
memcpy(info->key, md5->tcpm_key, TCP_MD5SIG_MAXKEYLEN);
info->key_len = md5->tcpm_keylen;
memset(&info->remote_addr, 0, sizeof(info->remote_addr));
if (md5->tcpm_addr.ss_family == AF_INET) {
#if LWIP_IPV4
const struct sockaddr_in *sin = (const struct sockaddr_in *)&md5->tcpm_addr;
memcpy(&info->remote_addr, &sin->sin_addr, sizeof(sin->sin_addr));
IP_SET_TYPE_VAL(info->remote_addr, IPADDR_TYPE_V4);
info->remote_port = lwip_htons(sin->sin_port);
addr_valid = 1;
#endif /* LWIP_IPV4 */
} else if (md5->tcpm_addr.ss_family == AF_INET6) {
#if LWIP_IPV6
const struct sockaddr_in6 *sin6 = (const struct sockaddr_in6 *)&md5->tcpm_addr;
memcpy(&info->remote_addr, &sin6->sin6_addr, sizeof(sin6->sin6_addr));
IP_SET_TYPE_VAL(info->remote_addr, IPADDR_TYPE_V6);
info->remote_port = lwip_htons(sin6->sin6_port);
addr_valid = 1;
#endif /* LWIP_IPV6 */
}
if (addr_valid) {
/* store it */
tcp_ext_arg_set_callbacks(sock->conn->pcb.tcp, tcp_md5_extarg_id, &tcp_md5_ext_arg_callbacks);
info->next = (struct tcp_md5_conn_info *)tcp_ext_arg_get(sock->conn->pcb.tcp, tcp_md5_extarg_id);
tcp_ext_arg_set(sock->conn->pcb.tcp, tcp_md5_extarg_id, info);
} else {
*err = EINVAL;
tcp_md5_conn_info_free(info);
}
}
}
} else {
/* not a tcp netconn */
*err = EINVAL;
}
}
return 1;
}
return 0;
}
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