[457] | 1 | /**
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| 2 | * @file: An implementation of TCP MD5 signatures by using various hooks in
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| 3 | * lwIP to implement custom tcp options and custom socket options.
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (c) 2018 Simon Goldschmidt
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| 8 | * All rights reserved.
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| 9 | *
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| 10 | * Redistribution and use in source and binary forms, with or without modification,
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| 11 | * are permitted provided that the following conditions are met:
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| 12 | *
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| 13 | * 1. Redistributions of source code must retain the above copyright notice,
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| 14 | * this list of conditions and the following disclaimer.
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| 15 | * 2. Redistributions in binary form must reproduce the above copyright notice,
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| 16 | * this list of conditions and the following disclaimer in the documentation
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| 17 | * and/or other materials provided with the distribution.
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| 18 | * 3. The name of the author may not be used to endorse or promote products
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| 19 | * derived from this software without specific prior written permission.
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| 20 | *
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| 21 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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| 22 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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| 23 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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| 24 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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| 25 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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| 26 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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| 27 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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| 28 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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| 29 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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| 30 | * OF SUCH DAMAGE.
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| 31 | *
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| 32 | * Author: Simon Goldschmidt <goldsimon@gmx.de>
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| 33 | */
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| 34 |
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| 35 | #include "tcp_md5.h"
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| 36 | #include "lwip/ip_addr.h"
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| 37 | #include "lwip/sys.h"
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| 38 | #include "lwip/prot/tcp.h"
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| 39 | #include "lwip/priv/tcp_priv.h"
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| 40 | #include "lwip/sockets.h"
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| 41 | #include "lwip/priv/sockets_priv.h"
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| 42 | #include "lwip/api.h"
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| 43 | #include <string.h>
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| 44 |
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| 45 | /* pull in md5 of ppp? */
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| 46 | #include "netif/ppp/ppp_opts.h"
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| 47 | #if !PPP_SUPPORT || (!LWIP_USE_EXTERNAL_POLARSSL && !LWIP_USE_EXTERNAL_MBEDTLS)
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| 48 | #undef LWIP_INCLUDED_POLARSSL_MD5
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| 49 | #define LWIP_INCLUDED_POLARSSL_MD5 1
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| 50 | #include "netif/ppp/polarssl/md5.h"
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| 51 | #endif
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| 52 |
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| 53 | #if !LWIP_TCP_PCB_NUM_EXT_ARGS
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| 54 | #error tcp_md5 needs LWIP_TCP_PCB_NUM_EXT_ARGS
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| 55 | #endif
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| 56 |
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| 57 | #define LWIP_TCP_OPT_MD5 19 /* number of the md5 option */
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| 58 | #define LWIP_TCP_OPT_LEN_MD5 18 /* length of the md5 option */
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| 59 | #define LWIP_TCP_OPT_LEN_MD5_OUT 20 /* 18 + alignment */
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| 60 |
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| 61 | #define LWIP_TCP_MD5_DIGEST_LEN 16
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| 62 |
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| 63 | /* This keeps the md5 state internally */
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| 64 | struct tcp_md5_conn_info {
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| 65 | struct tcp_md5_conn_info *next;
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| 66 | ip_addr_t remote_addr;
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| 67 | u16_t remote_port;
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| 68 | u8_t key[TCP_MD5SIG_MAXKEYLEN];
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| 69 | u16_t key_len;
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| 70 | };
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| 71 |
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| 72 | /* Callback function prototypes: */
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| 73 | static void tcp_md5_extarg_destroy(u8_t id, void *data);
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| 74 | static err_t tcp_md5_extarg_passive_open(u8_t id, struct tcp_pcb_listen *lpcb, struct tcp_pcb *cpcb);
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| 75 | /* Define our tcp ext arg callback structure: */
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| 76 | const struct tcp_ext_arg_callbacks tcp_md5_ext_arg_callbacks = {
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| 77 | tcp_md5_extarg_destroy,
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| 78 | tcp_md5_extarg_passive_open
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| 79 | };
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| 80 |
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| 81 | static u8_t tcp_md5_extarg_id = LWIP_TCP_PCB_NUM_EXT_ARG_ID_INVALID;
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| 82 | static u8_t tcp_md5_opts_buf[40];
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| 83 |
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| 84 | /** Initialize this module (allocates a tcp ext arg id) */
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| 85 | void
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| 86 | tcp_md5_init(void)
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| 87 | {
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| 88 | tcp_md5_extarg_id = tcp_ext_arg_alloc_id();
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| 89 | }
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| 90 |
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| 91 | /* Create a conn-info structure that holds the md5 state per connection */
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| 92 | static struct tcp_md5_conn_info *
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| 93 | tcp_md5_conn_info_alloc(void)
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| 94 | {
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| 95 | return (struct tcp_md5_conn_info *)mem_malloc(sizeof(struct tcp_md5_conn_info));
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| 96 | }
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| 97 |
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| 98 | /* Frees a conn-info structure that holds the md5 state per connection */
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| 99 | static void
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| 100 | tcp_md5_conn_info_free(struct tcp_md5_conn_info *info)
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| 101 | {
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| 102 | mem_free(info);
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| 103 | }
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| 104 |
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| 105 | /* A pcb is about to be destroyed. Free its extdata */
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| 106 | static void
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| 107 | tcp_md5_extarg_destroy(u8_t id, void *data)
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| 108 | {
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| 109 | struct tcp_md5_conn_info *iter;
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| 110 |
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| 111 | LWIP_ASSERT("tcp_md5_extarg_id != LWIP_TCP_PCB_NUM_EXT_ARG_ID_INVALID",
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| 112 | tcp_md5_extarg_id != LWIP_TCP_PCB_NUM_EXT_ARG_ID_INVALID);
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| 113 | LWIP_ASSERT("id == tcp_md5_extarg_id", id == tcp_md5_extarg_id);
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| 114 | LWIP_UNUSED_ARG(id);
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| 115 |
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| 116 | iter = (struct tcp_md5_conn_info *)data;
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| 117 | while (iter != NULL) {
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| 118 | struct tcp_md5_conn_info *info = iter;
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| 119 | iter = iter->next;
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| 120 | tcp_md5_conn_info_free(info);
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| 121 | }
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| 122 | }
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| 123 |
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| 124 | /* Try to find an md5 connection info for the specified remote connection */
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| 125 | static struct tcp_md5_conn_info *
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| 126 | tcp_md5_get_info(const struct tcp_pcb *pcb, const ip_addr_t *remote_ip, u16_t remote_port)
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| 127 | {
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| 128 | if (pcb != NULL) {
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| 129 | struct tcp_md5_conn_info *info = (struct tcp_md5_conn_info *)tcp_ext_arg_get(pcb, tcp_md5_extarg_id);
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| 130 | while (info != NULL) {
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| 131 | if (ip_addr_cmp(&info->remote_addr, remote_ip)) {
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| 132 | if (info->remote_port == remote_port) {
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| 133 | return info;
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| 134 | }
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| 135 | }
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| 136 | info = info->next;
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| 137 | }
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| 138 | }
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| 139 | return NULL;
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| 140 | }
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| 141 |
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| 142 | /* Passive open: copy md5 connection info from listen pcb to connection pcb
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| 143 | * or return error (connection will be closed)
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| 144 | */
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| 145 | static err_t
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| 146 | tcp_md5_extarg_passive_open(u8_t id, struct tcp_pcb_listen *lpcb, struct tcp_pcb *cpcb)
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| 147 | {
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| 148 | struct tcp_md5_conn_info *iter;
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| 149 |
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| 150 | LWIP_ASSERT("lpcb != NULL", lpcb != NULL);
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| 151 | LWIP_ASSERT("cpcb != NULL", cpcb != NULL);
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| 152 | LWIP_ASSERT("tcp_md5_extarg_id != LWIP_TCP_PCB_NUM_EXT_ARG_ID_INVALID",
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| 153 | tcp_md5_extarg_id != LWIP_TCP_PCB_NUM_EXT_ARG_ID_INVALID);
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| 154 | LWIP_ASSERT("id == tcp_md5_extarg_id", id == tcp_md5_extarg_id);
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| 155 | LWIP_UNUSED_ARG(id);
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| 156 |
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| 157 | iter = (struct tcp_md5_conn_info *)tcp_ext_arg_get((struct tcp_pcb *)lpcb, id);
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| 158 | while (iter != NULL) {
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| 159 | if (iter->remote_port == cpcb->remote_port) {
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| 160 | if (ip_addr_cmp(&iter->remote_addr, &cpcb->remote_ip)) {
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| 161 | struct tcp_md5_conn_info *info = tcp_md5_conn_info_alloc();
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| 162 | if (info != NULL) {
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| 163 | memcpy(info, iter, sizeof(struct tcp_md5_conn_info));
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| 164 | tcp_ext_arg_set(cpcb, id, info);
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| 165 | tcp_ext_arg_set_callbacks(cpcb, id, &tcp_md5_ext_arg_callbacks);
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| 166 | return ERR_OK;
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| 167 | } else {
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| 168 | return ERR_MEM;
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| 169 | }
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| 170 | }
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| 171 | }
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| 172 | iter = iter->next;
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| 173 | }
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| 174 | /* remote connection not found */
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| 175 | return ERR_VAL;
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| 176 | }
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| 177 |
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| 178 | /* Parse tcp header options and return 1 if an md5 signature option was found */
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| 179 | static int
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| 180 | tcp_md5_parseopt(const u8_t *opts, u16_t optlen, u8_t *md5_digest_out)
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| 181 | {
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| 182 | u8_t data;
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| 183 | u16_t optidx;
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| 184 |
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| 185 | /* Parse the TCP MSS option, if present. */
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| 186 | if (optlen != 0) {
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| 187 | for (optidx = 0; optidx < optlen; ) {
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| 188 | u8_t opt = opts[optidx++];
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| 189 | switch (opt) {
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| 190 | case LWIP_TCP_OPT_EOL:
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| 191 | /* End of options. */
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| 192 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: EOL\n"));
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| 193 | return 0;
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| 194 | case LWIP_TCP_OPT_NOP:
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| 195 | /* NOP option. */
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| 196 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: NOP\n"));
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| 197 | break;
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| 198 | case LWIP_TCP_OPT_MD5:
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| 199 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: MD5\n"));
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| 200 | if (opts[optidx++] != LWIP_TCP_OPT_LEN_MD5 || (optidx - 2 + LWIP_TCP_OPT_LEN_MD5) > optlen) {
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| 201 | /* Bad length */
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| 202 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
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| 203 | return 0;
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| 204 | }
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| 205 | /* An MD5 option with the right option length. */
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| 206 | memcpy(md5_digest_out, &opts[optidx], LWIP_TCP_MD5_DIGEST_LEN);
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| 207 | /* no need to process the options further */
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| 208 | return 1;
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| 209 | break;
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| 210 | default:
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| 211 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: other\n"));
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| 212 | data = opts[optidx++];
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| 213 | if (data < 2) {
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| 214 | LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
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| 215 | /* If the length field is zero, the options are malformed
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| 216 | and we don't process them further. */
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| 217 | return 0;
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| 218 | }
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| 219 | /* All other options have a length field, so that we easily
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| 220 | can skip past them. */
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| 221 | optidx += data - 2;
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| 222 | }
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| 223 | }
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| 224 | }
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| 225 | return 0;
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| 226 | }
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| 227 |
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| 228 | /* Get tcp options into contiguous memory. May be required if input pbufs
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| 229 | * are chained.
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| 230 | */
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| 231 | static const u8_t*
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| 232 | tcp_md5_options_singlebuf(struct tcp_hdr *hdr, u16_t optlen, u16_t opt1len, u8_t *opt2)
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| 233 | {
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| 234 | const u8_t *opts;
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| 235 | LWIP_ASSERT("hdr != NULL", hdr != NULL);
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| 236 | LWIP_ASSERT("optlen >= opt1len", optlen >= opt1len);
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| 237 | opts = (const u8_t *)hdr + TCP_HLEN;
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| 238 | if (optlen == opt1len) {
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| 239 | /* arleady in one piece */
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| 240 | return opts;
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| 241 | }
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| 242 | if (optlen > sizeof(tcp_md5_opts_buf)) {
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| 243 | /* options too long */
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| 244 | return NULL;
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| 245 | }
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| 246 | LWIP_ASSERT("opt2 != NULL", opt2 != NULL);
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| 247 | /* copy first part */
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| 248 | memcpy(tcp_md5_opts_buf, opts, opt1len);
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| 249 | /* copy second part */
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| 250 | memcpy(&tcp_md5_opts_buf[opt1len], opt2, optlen - opt1len);
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| 251 | return tcp_md5_opts_buf;
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| 252 | }
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| 253 |
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| 254 | /* Create the md5 digest for a given segment */
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| 255 | static int
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| 256 | tcp_md5_create_digest(const ip_addr_t *ip_src, const ip_addr_t *ip_dst, const struct tcp_hdr *hdr,
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| 257 | const u8_t *key, size_t key_len, u8_t *digest_out, struct pbuf *p)
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| 258 | {
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| 259 | md5_context ctx;
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| 260 | u8_t tmp8;
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| 261 | u16_t tmp16;
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| 262 | const size_t addr_len = IP_ADDR_RAW_SIZE(*ip_src);
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| 263 |
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| 264 | if (p != NULL) {
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| 265 | LWIP_ASSERT("pbuf must not point to tcp header here!", (const void *)hdr != p->payload);
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| 266 | }
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| 267 |
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| 268 | /* Generate the hash, using MD5. */
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| 269 | md5_starts(&ctx);
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| 270 | /* 1. the TCP pseudo-header (in the order: source IP address,
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| 271 | destination IP address, zero-padded protocol number, and
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| 272 | segment length) */
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| 273 | md5_update(&ctx, (const unsigned char*)ip_src, addr_len);
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| 274 | md5_update(&ctx, (const unsigned char*)ip_dst, addr_len);
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| 275 | tmp8 = 0; /* zero-padded */
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| 276 | md5_update(&ctx, &tmp8, 1);
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| 277 | tmp8 = IP_PROTO_TCP;
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| 278 | md5_update(&ctx, &tmp8, 1);
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| 279 | tmp16 = lwip_htons(TCPH_HDRLEN_BYTES(hdr) + (p ? p->tot_len : 0));
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| 280 | md5_update(&ctx, (const unsigned char*)&tmp16, 2);
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| 281 | /* 2. the TCP header, excluding options, and assuming a checksum of
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| 282 | zero */
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| 283 | md5_update(&ctx, (const unsigned char*)hdr, sizeof(struct tcp_hdr));
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| 284 | /* 3. the TCP segment data (if any) */
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| 285 | if ((p != NULL) && (p->tot_len != 0)) {
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| 286 | struct pbuf *q;
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| 287 | for (q = p; q != NULL; q = q->next) {
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| 288 | md5_update(&ctx, (const unsigned char*)q->payload, q->len);
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| 289 | }
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| 290 | }
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| 291 | /* 4. an independently-specified key or password, known to both TCPs
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| 292 | and presumably connection-specific */
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| 293 | md5_update(&ctx, key, key_len);
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| 294 |
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| 295 | md5_finish(&ctx, digest_out);
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| 296 | return 1;
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| 297 | }
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| 298 |
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| 299 | /* Duplicate a tcp header and make sure the fields are in network byte order */
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| 300 | static void
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| 301 | tcp_md5_dup_tcphdr(struct tcp_hdr *tcphdr_copy, const struct tcp_hdr *tcphdr_in, int tcphdr_in_is_host_order)
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| 302 | {
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| 303 | memcpy(tcphdr_copy, tcphdr_in, sizeof(struct tcp_hdr));
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| 304 | tcphdr_copy->chksum = 0; /* checksum is zero for the pseudo header */
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| 305 | if (tcphdr_in_is_host_order) {
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| 306 | /* lwIP writes the TCP header values back to the buffer, we need to invert that here: */
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| 307 | tcphdr_copy->src = lwip_htons(tcphdr_copy->src);
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| 308 | tcphdr_copy->dest = lwip_htons(tcphdr_copy->dest);
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| 309 | tcphdr_copy->seqno = lwip_htonl(tcphdr_copy->seqno);
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| 310 | tcphdr_copy->ackno = lwip_htonl(tcphdr_copy->ackno);
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| 311 | tcphdr_copy->wnd = lwip_htons(tcphdr_copy->wnd);
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| 312 | tcphdr_copy->urgp = lwip_htons(tcphdr_copy->urgp);
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| 313 | }
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| 314 | }
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| 315 |
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| 316 | /* Check if md5 is enabled on a given pcb */
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| 317 | static int
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| 318 | tcp_md5_is_enabled_on_pcb(const struct tcp_pcb *pcb)
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| 319 | {
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| 320 | if (tcp_md5_extarg_id != LWIP_TCP_PCB_NUM_EXT_ARG_ID_INVALID) {
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| 321 | struct tcp_md5_conn_info *info = (struct tcp_md5_conn_info *)tcp_ext_arg_get(pcb, tcp_md5_extarg_id);
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| 322 | if (info != NULL) {
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| 323 | return 1;
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| 324 | }
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| 325 | }
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| 326 | return 0;
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| 327 | }
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| 328 |
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| 329 | /* Check if md5 is enabled on a given listen pcb */
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| 330 | static int
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| 331 | tcp_md5_is_enabled_on_lpcb(const struct tcp_pcb_listen *lpcb)
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| 332 | {
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| 333 | /* same as for connection pcbs */
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| 334 | return tcp_md5_is_enabled_on_pcb((const struct tcp_pcb *)lpcb);
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| 335 | }
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| 336 |
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| 337 | /* Hook implementation for LWIP_HOOK_TCP_OPT_LENGTH_SEGMENT */
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| 338 | u8_t
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| 339 | tcp_md5_get_additional_option_length(const struct tcp_pcb *pcb, u8_t internal_option_length)
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| 340 | {
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| 341 | if ((pcb != NULL) && tcp_md5_is_enabled_on_pcb(pcb)) {
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| 342 | u8_t new_option_length = internal_option_length + LWIP_TCP_OPT_LEN_MD5_OUT;
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| 343 | LWIP_ASSERT("overflow", new_option_length > internal_option_length);
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| 344 | LWIP_ASSERT("options too long", new_option_length <= TCP_MAX_OPTION_BYTES);
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| 345 | return new_option_length;
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| 346 | }
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| 347 | return internal_option_length;
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| 348 | }
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| 349 |
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| 350 | /* Hook implementation for LWIP_HOOK_TCP_INPACKET_PCB when called for listen pcbs */
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| 351 | static err_t
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| 352 | tcp_md5_check_listen(struct tcp_pcb_listen* lpcb, struct tcp_hdr *hdr, u16_t optlen, u16_t opt1len, u8_t *opt2)
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| 353 | {
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| 354 | LWIP_ASSERT("lpcb != NULL", lpcb != NULL);
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| 355 |
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| 356 | if (tcp_md5_is_enabled_on_lpcb(lpcb)) {
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| 357 | const u8_t *opts;
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| 358 | u8_t digest_received[LWIP_TCP_MD5_DIGEST_LEN];
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| 359 | u8_t digest_calculated[LWIP_TCP_MD5_DIGEST_LEN];
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| 360 | const struct tcp_md5_conn_info *info = tcp_md5_get_info((struct tcp_pcb *)lpcb, ip_current_src_addr(), hdr->src);
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| 361 | if (info != NULL) {
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| 362 | opts = tcp_md5_options_singlebuf(hdr, optlen, opt1len, opt2);
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| 363 | if (opts != NULL) {
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| 364 | if (tcp_md5_parseopt(opts, optlen, digest_received)) {
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| 365 | struct tcp_hdr tcphdr_copy;
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| 366 | tcp_md5_dup_tcphdr(&tcphdr_copy, hdr, 1);
|
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| 367 | if (tcp_md5_create_digest(ip_current_src_addr(), ip_current_dest_addr(), &tcphdr_copy, info->key, info->key_len, digest_calculated, NULL)) {
|
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| 368 | /* everything set up, compare the digests */
|
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| 369 | if (!memcmp(digest_received, digest_calculated, LWIP_TCP_MD5_DIGEST_LEN)) {
|
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| 370 | /* equal */
|
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| 371 | return ERR_OK;
|
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| 372 | }
|
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| 373 | /* not equal */
|
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| 374 | }
|
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| 375 | }
|
---|
| 376 | }
|
---|
| 377 | }
|
---|
| 378 | /* md5 enabled on this pcb but no match or other error -> fail */
|
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| 379 | return ERR_VAL;
|
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| 380 | }
|
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| 381 | return ERR_OK;
|
---|
| 382 | }
|
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| 383 |
|
---|
| 384 | /* Hook implementation for LWIP_HOOK_TCP_INPACKET_PCB */
|
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| 385 | err_t
|
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| 386 | tcp_md5_check_inpacket(struct tcp_pcb* pcb, struct tcp_hdr *hdr, u16_t optlen, u16_t opt1len, u8_t *opt2, struct pbuf *p)
|
---|
| 387 | {
|
---|
| 388 | LWIP_ASSERT("pcb != NULL", pcb != NULL);
|
---|
| 389 |
|
---|
| 390 | if (pcb->state == LISTEN) {
|
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| 391 | return tcp_md5_check_listen((struct tcp_pcb_listen *)pcb, hdr, optlen, opt1len, opt2);
|
---|
| 392 | }
|
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| 393 |
|
---|
| 394 | if (tcp_md5_is_enabled_on_pcb(pcb)) {
|
---|
| 395 | const struct tcp_md5_conn_info *info = tcp_md5_get_info(pcb, ip_current_src_addr(), hdr->src);
|
---|
| 396 | if (info != NULL) {
|
---|
| 397 | const u8_t *opts;
|
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| 398 | u8_t digest_received[LWIP_TCP_MD5_DIGEST_LEN];
|
---|
| 399 | u8_t digest_calculated[LWIP_TCP_MD5_DIGEST_LEN];
|
---|
| 400 | opts = tcp_md5_options_singlebuf(hdr, optlen, opt1len, opt2);
|
---|
| 401 | if (opts != NULL) {
|
---|
| 402 | if (tcp_md5_parseopt(opts, optlen, digest_received)) {
|
---|
| 403 | struct tcp_hdr hdr_copy;
|
---|
| 404 | tcp_md5_dup_tcphdr(&hdr_copy, hdr, 1);
|
---|
| 405 | if (tcp_md5_create_digest(&pcb->remote_ip, &pcb->local_ip, &hdr_copy, info->key, info->key_len, digest_calculated, p)) {
|
---|
| 406 | /* everything set up, compare the digests */
|
---|
| 407 | if (!memcmp(digest_received, digest_calculated, LWIP_TCP_MD5_DIGEST_LEN)) {
|
---|
| 408 | /* equal */
|
---|
| 409 | return ERR_OK;
|
---|
| 410 | }
|
---|
| 411 | /* not equal */
|
---|
| 412 | }
|
---|
| 413 | }
|
---|
| 414 | }
|
---|
| 415 | }
|
---|
| 416 | /* md5 enabled on this pcb but no match or other error -> fail */
|
---|
| 417 | return ERR_VAL;
|
---|
| 418 | }
|
---|
| 419 | return ERR_OK;
|
---|
| 420 | }
|
---|
| 421 |
|
---|
| 422 | /* Hook implementation for LWIP_HOOK_TCP_ADD_TX_OPTIONS */
|
---|
| 423 | u32_t *
|
---|
| 424 | tcp_md5_add_tx_options(struct pbuf *p, struct tcp_hdr *hdr, const struct tcp_pcb *pcb, u32_t *opts)
|
---|
| 425 | {
|
---|
| 426 | LWIP_ASSERT("p != NULL", p != NULL);
|
---|
| 427 | LWIP_ASSERT("hdr != NULL", hdr != NULL);
|
---|
| 428 | LWIP_ASSERT("pcb != NULL", pcb != NULL);
|
---|
| 429 | LWIP_ASSERT("opts != NULL", opts != NULL);
|
---|
| 430 |
|
---|
| 431 | if (tcp_md5_is_enabled_on_pcb(pcb)) {
|
---|
| 432 | u8_t digest_calculated[LWIP_TCP_MD5_DIGEST_LEN];
|
---|
| 433 | u32_t *opts_ret = opts + 5; /* we use 20 bytes: 2 bytes padding + 18 bytes for this option */
|
---|
| 434 | u8_t *ptr = (u8_t*)opts;
|
---|
| 435 |
|
---|
| 436 | const struct tcp_md5_conn_info *info = tcp_md5_get_info(pcb, &pcb->remote_ip, pcb->remote_port);
|
---|
| 437 | if (info != NULL) {
|
---|
| 438 | struct tcp_hdr hdr_copy;
|
---|
| 439 | size_t hdrsize = TCPH_HDRLEN_BYTES(hdr);
|
---|
| 440 | tcp_md5_dup_tcphdr(&hdr_copy, hdr, 0);
|
---|
| 441 | /* p->payload points to the tcp header */
|
---|
| 442 | LWIP_ASSERT("p->payload == hdr", p->payload == hdr);
|
---|
| 443 | if (!pbuf_remove_header(p, hdrsize)) {
|
---|
| 444 | u8_t ret;
|
---|
| 445 | if (!tcp_md5_create_digest(&pcb->local_ip, &pcb->remote_ip, &hdr_copy, info->key, info->key_len, digest_calculated, p)) {
|
---|
| 446 | info = NULL;
|
---|
| 447 | }
|
---|
| 448 | ret = pbuf_add_header_force(p, hdrsize);
|
---|
| 449 | LWIP_ASSERT("tcp_md5_add_tx_options: pbuf_add_header_force failed", !ret);
|
---|
| 450 | LWIP_UNUSED_ARG(ret);
|
---|
| 451 | } else {
|
---|
| 452 | LWIP_ASSERT("error", 0);
|
---|
| 453 | }
|
---|
| 454 | }
|
---|
| 455 | if (info == NULL) {
|
---|
| 456 | /* create an invalid signature by zeroing the digest */
|
---|
| 457 | memset(&digest_calculated, 0, sizeof(digest_calculated));
|
---|
| 458 | }
|
---|
| 459 |
|
---|
| 460 | *ptr++ = LWIP_TCP_OPT_NOP;
|
---|
| 461 | *ptr++ = LWIP_TCP_OPT_NOP;
|
---|
| 462 | *ptr++ = LWIP_TCP_OPT_MD5;
|
---|
| 463 | *ptr++ = LWIP_TCP_OPT_LEN_MD5;
|
---|
| 464 | memcpy(ptr, digest_calculated, LWIP_TCP_MD5_DIGEST_LEN);
|
---|
| 465 | ptr += LWIP_TCP_MD5_DIGEST_LEN;
|
---|
| 466 | LWIP_ASSERT("ptr == opts_ret", ptr == (u8_t *)opts_ret);
|
---|
| 467 | return opts_ret;
|
---|
| 468 | }
|
---|
| 469 | return opts;
|
---|
| 470 | }
|
---|
| 471 |
|
---|
| 472 | /* Hook implementation for LWIP_HOOK_SOCKETS_SETSOCKOPT */
|
---|
| 473 | int
|
---|
| 474 | tcp_md5_setsockopt_hook(struct lwip_sock *sock, int level, int optname, const void *optval, socklen_t optlen, int *err)
|
---|
| 475 | {
|
---|
| 476 | LWIP_ASSERT("sock != NULL", sock != NULL);
|
---|
| 477 | LWIP_ASSERT("err != NULL", err != NULL);
|
---|
| 478 |
|
---|
| 479 | if ((level == IPPROTO_TCP) && (optname == TCP_MD5SIG)) {
|
---|
| 480 | const struct tcp_md5sig *md5 = (const struct tcp_md5sig*)optval;
|
---|
| 481 | if ((optval == NULL) || (optlen < sizeof(struct tcp_md5sig))) {
|
---|
| 482 | *err = EINVAL;
|
---|
| 483 | } else {
|
---|
| 484 | if (sock->conn && (NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) && (sock->conn->pcb.tcp != NULL)) {
|
---|
| 485 | if (tcp_md5_extarg_id == LWIP_TCP_PCB_NUM_EXT_ARG_ID_INVALID) {
|
---|
| 486 | /* not initialized */
|
---|
| 487 | *err = EINVAL;
|
---|
| 488 | } else {
|
---|
| 489 | struct tcp_md5_conn_info *info = tcp_md5_conn_info_alloc();
|
---|
| 490 | if (info == NULL) {
|
---|
| 491 | *err = ENOMEM;
|
---|
| 492 | } else {
|
---|
| 493 | int addr_valid = 0;
|
---|
| 494 | /* OK, fill and link this request */
|
---|
| 495 | memcpy(info->key, md5->tcpm_key, TCP_MD5SIG_MAXKEYLEN);
|
---|
| 496 | info->key_len = md5->tcpm_keylen;
|
---|
| 497 | memset(&info->remote_addr, 0, sizeof(info->remote_addr));
|
---|
| 498 | if (md5->tcpm_addr.ss_family == AF_INET) {
|
---|
| 499 | #if LWIP_IPV4
|
---|
| 500 | const struct sockaddr_in *sin = (const struct sockaddr_in *)&md5->tcpm_addr;
|
---|
| 501 | memcpy(&info->remote_addr, &sin->sin_addr, sizeof(sin->sin_addr));
|
---|
| 502 | IP_SET_TYPE_VAL(info->remote_addr, IPADDR_TYPE_V4);
|
---|
| 503 | info->remote_port = lwip_htons(sin->sin_port);
|
---|
| 504 | addr_valid = 1;
|
---|
| 505 | #endif /* LWIP_IPV4 */
|
---|
| 506 | } else if (md5->tcpm_addr.ss_family == AF_INET6) {
|
---|
| 507 | #if LWIP_IPV6
|
---|
| 508 | const struct sockaddr_in6 *sin6 = (const struct sockaddr_in6 *)&md5->tcpm_addr;
|
---|
| 509 | memcpy(&info->remote_addr, &sin6->sin6_addr, sizeof(sin6->sin6_addr));
|
---|
| 510 | IP_SET_TYPE_VAL(info->remote_addr, IPADDR_TYPE_V6);
|
---|
| 511 | info->remote_port = lwip_htons(sin6->sin6_port);
|
---|
| 512 | addr_valid = 1;
|
---|
| 513 | #endif /* LWIP_IPV6 */
|
---|
| 514 | }
|
---|
| 515 | if (addr_valid) {
|
---|
| 516 | /* store it */
|
---|
| 517 | tcp_ext_arg_set_callbacks(sock->conn->pcb.tcp, tcp_md5_extarg_id, &tcp_md5_ext_arg_callbacks);
|
---|
| 518 | info->next = (struct tcp_md5_conn_info *)tcp_ext_arg_get(sock->conn->pcb.tcp, tcp_md5_extarg_id);
|
---|
| 519 | tcp_ext_arg_set(sock->conn->pcb.tcp, tcp_md5_extarg_id, info);
|
---|
| 520 | } else {
|
---|
| 521 | *err = EINVAL;
|
---|
| 522 | tcp_md5_conn_info_free(info);
|
---|
| 523 | }
|
---|
| 524 | }
|
---|
| 525 | }
|
---|
| 526 | } else {
|
---|
| 527 | /* not a tcp netconn */
|
---|
| 528 | *err = EINVAL;
|
---|
| 529 | }
|
---|
| 530 | }
|
---|
| 531 | return 1;
|
---|
| 532 | }
|
---|
| 533 | return 0;
|
---|
| 534 | }
|
---|