takashi kadono / Mbed OS Nucleo446_SSD1331

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Dependencies:   ssd1331

mbed-os/features/lwipstack/lwip-sys/lwip_tcp_isn.c@3:f3764f852aa8, 2018-10-11 (annotated)

Committer:
kadonotakashi
Date:
Thu Oct 11 02:27:46 2018 +0000
Revision:
3:f3764f852aa8
Parent:
0:8fdf9a60065b 
Nucreo 446 + SSD1331 test version;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
kadonotakashi 0:8fdf9a60065b 1 /**
kadonotakashi 0:8fdf9a60065b 2 * @file
kadonotakashi 0:8fdf9a60065b 3 *
kadonotakashi 0:8fdf9a60065b 4 * Reference implementation of the TCP ISN algorithm standardized in RFC 6528.
kadonotakashi 0:8fdf9a60065b 5 * Produce TCP Initial Sequence Numbers by combining an MD5-generated hash
kadonotakashi 0:8fdf9a60065b 6 * based on the new TCP connection's identity and a stable secret, with the
kadonotakashi 0:8fdf9a60065b 7 * current time at 4-microsecond granularity.
kadonotakashi 0:8fdf9a60065b 8 *
kadonotakashi 0:8fdf9a60065b 9 * Specifically, the implementation uses MD5 to compute a hash of the input
kadonotakashi 0:8fdf9a60065b 10 * buffer, which contains both the four-tuple of the new TCP connection (local
kadonotakashi 0:8fdf9a60065b 11 * and remote IP address and port), as well as a 16-byte secret to make the
kadonotakashi 0:8fdf9a60065b 12 * results unpredictable to external parties. The secret must be given at
kadonotakashi 0:8fdf9a60065b 13 * initialization time and should ideally remain the same across system
kadonotakashi 0:8fdf9a60065b 14 * reboots. To be sure: the spoofing-resistance of the resulting ISN depends
kadonotakashi 0:8fdf9a60065b 15 * mainly on the strength of the supplied secret!
kadonotakashi 0:8fdf9a60065b 16 *
kadonotakashi 0:8fdf9a60065b 17 * The implementation takes 32 bits from the computed hash, and adds to it the
kadonotakashi 0:8fdf9a60065b 18 * current time, in 4-microsecond units. The current time is computed from a
kadonotakashi 0:8fdf9a60065b 19 * boot time given at initialization, and the current uptime as provided by
kadonotakashi 0:8fdf9a60065b 20 * sys_now(). Thus, it assumes that sys_now() returns a time value that is
kadonotakashi 0:8fdf9a60065b 21 * relative to the boot time, i.e., that it starts at 0 at system boot, and
kadonotakashi 0:8fdf9a60065b 22 * only ever increases monotonically.
kadonotakashi 0:8fdf9a60065b 23 *
kadonotakashi 0:8fdf9a60065b 24 * For efficiency reasons, a single MD5 input buffer is used, and partially
kadonotakashi 0:8fdf9a60065b 25 * filled in at initialization time. Specifically, of this 64-byte buffer, the
kadonotakashi 0:8fdf9a60065b 26 * first 36 bytes are used for the four-way TCP tuple data, followed by the
kadonotakashi 0:8fdf9a60065b 27 * 16-byte secret, followed by 12-byte zero padding. The 64-byte size of the
kadonotakashi 0:8fdf9a60065b 28 * buffer should achieve the best performance for the actual MD5 computation.
kadonotakashi 0:8fdf9a60065b 29 *
kadonotakashi 0:8fdf9a60065b 30 * Basic usage:
kadonotakashi 0:8fdf9a60065b 31 *
kadonotakashi 0:8fdf9a60065b 32 * 1. in your lwipopts.h, add the following lines:
kadonotakashi 0:8fdf9a60065b 33 *
kadonotakashi 0:8fdf9a60065b 34 * #include <lwip/arch.h>
kadonotakashi 0:8fdf9a60065b 35 * struct ip_addr;
kadonotakashi 0:8fdf9a60065b 36 * u32_t lwip_hook_tcp_isn(const struct ip_addr *local_ip, u16_t local_port,
kadonotakashi 0:8fdf9a60065b 37 * const struct ip_addr *remote_ip, u16_t remote_port);
kadonotakashi 0:8fdf9a60065b 38 * "#define LWIP_HOOK_TCP_ISN lwip_hook_tcp_isn";
kadonotakashi 0:8fdf9a60065b 39 *
kadonotakashi 0:8fdf9a60065b 40 * 2. from your own code, call lwip_init_tcp_isn() at initialization time, with
kadonotakashi 0:8fdf9a60065b 41 * appropriate parameters.
kadonotakashi 0:8fdf9a60065b 42 */
kadonotakashi 0:8fdf9a60065b 43
kadonotakashi 0:8fdf9a60065b 44 /*
kadonotakashi 0:8fdf9a60065b 45 * Copyright (c) 2016 The MINIX 3 Project.
kadonotakashi 0:8fdf9a60065b 46 * All rights reserved.
kadonotakashi 0:8fdf9a60065b 47 *
kadonotakashi 0:8fdf9a60065b 48 * Redistribution and use in source and binary forms, with or without modification,
kadonotakashi 0:8fdf9a60065b 49 * are permitted provided that the following conditions are met:
kadonotakashi 0:8fdf9a60065b 50 *
kadonotakashi 0:8fdf9a60065b 51 * 1. Redistributions of source code must retain the above copyright notice,
kadonotakashi 0:8fdf9a60065b 52 * this list of conditions and the following disclaimer.
kadonotakashi 0:8fdf9a60065b 53 * 2. Redistributions in binary form must reproduce the above copyright notice,
kadonotakashi 0:8fdf9a60065b 54 * this list of conditions and the following disclaimer in the documentation
kadonotakashi 0:8fdf9a60065b 55 * and/or other materials provided with the distribution.
kadonotakashi 0:8fdf9a60065b 56 * 3. The name of the author may not be used to endorse or promote products
kadonotakashi 0:8fdf9a60065b 57 * derived from this software without specific prior written permission.
kadonotakashi 0:8fdf9a60065b 58 *
kadonotakashi 0:8fdf9a60065b 59 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
kadonotakashi 0:8fdf9a60065b 60 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
kadonotakashi 0:8fdf9a60065b 61 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
kadonotakashi 0:8fdf9a60065b 62 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
kadonotakashi 0:8fdf9a60065b 63 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
kadonotakashi 0:8fdf9a60065b 64 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
kadonotakashi 0:8fdf9a60065b 65 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
kadonotakashi 0:8fdf9a60065b 66 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
kadonotakashi 0:8fdf9a60065b 67 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
kadonotakashi 0:8fdf9a60065b 68 * OF SUCH DAMAGE.
kadonotakashi 0:8fdf9a60065b 69 *
kadonotakashi 0:8fdf9a60065b 70 * Author: David van Moolenbroek <david@minix3.org>
kadonotakashi 0:8fdf9a60065b 71 */
kadonotakashi 0:8fdf9a60065b 72
kadonotakashi 0:8fdf9a60065b 73 #include "lwip/opt.h"
kadonotakashi 0:8fdf9a60065b 74 #include "lwip/ip_addr.h"
kadonotakashi 0:8fdf9a60065b 75 #include "lwip/sys.h"
kadonotakashi 0:8fdf9a60065b 76 #include <string.h>
kadonotakashi 0:8fdf9a60065b 77
kadonotakashi 0:8fdf9a60065b 78 /* pull in md5 of ppp? */
kadonotakashi 0:8fdf9a60065b 79 #if !PPP_SUPPORT
kadonotakashi 0:8fdf9a60065b 80 #undef PPP_SUPPORT
kadonotakashi 0:8fdf9a60065b 81 #define PPP_SUPPORT 1
kadonotakashi 0:8fdf9a60065b 82 #define PPP_FAKED_ON 1
kadonotakashi 0:8fdf9a60065b 83 #endif
kadonotakashi 0:8fdf9a60065b 84
kadonotakashi 0:8fdf9a60065b 85 #include "netif/ppp/ppp_opts.h"
kadonotakashi 0:8fdf9a60065b 86 #include "netif/ppp/ppp.h"
kadonotakashi 0:8fdf9a60065b 87 #include "netif/ppp/pppcrypt.h"
kadonotakashi 0:8fdf9a60065b 88
kadonotakashi 0:8fdf9a60065b 89 #if PPP_FAKED_ON && !LWIP_USE_EXTERNAL_POLARSSL && !LWIP_USE_EXTERNAL_MBEDTLS
kadonotakashi 0:8fdf9a60065b 90 #undef LWIP_INCLUDED_POLARSSL_MD5
kadonotakashi 0:8fdf9a60065b 91 #define LWIP_INCLUDED_POLARSSL_MD5 1
kadonotakashi 0:8fdf9a60065b 92 #include "netif/ppp/polarssl/lwip_md5.c"
kadonotakashi 0:8fdf9a60065b 93 #endif
kadonotakashi 0:8fdf9a60065b 94
kadonotakashi 0:8fdf9a60065b 95 static u8_t input[64];
kadonotakashi 0:8fdf9a60065b 96 static u32_t base_time;
kadonotakashi 0:8fdf9a60065b 97
kadonotakashi 0:8fdf9a60065b 98 /**
kadonotakashi 0:8fdf9a60065b 99 * Initialize the TCP ISN module, with the boot time and a secret.
kadonotakashi 0:8fdf9a60065b 100 *
kadonotakashi 0:8fdf9a60065b 101 * @param boot_time Wall clock boot time of the system, in seconds.
kadonotakashi 0:8fdf9a60065b 102 * @param secret_16_bytes A 16-byte secret used to randomize the TCP ISNs.
kadonotakashi 0:8fdf9a60065b 103 */
kadonotakashi 0:8fdf9a60065b 104 void
kadonotakashi 0:8fdf9a60065b 105 lwip_init_tcp_isn(u32_t boot_time, const u8_t *secret_16_bytes)
kadonotakashi 0:8fdf9a60065b 106 {
kadonotakashi 0:8fdf9a60065b 107 /* Initialize the input buffer with the secret and trailing zeroes. */
kadonotakashi 0:8fdf9a60065b 108 memset(input, 0, sizeof(input));
kadonotakashi 0:8fdf9a60065b 109
kadonotakashi 0:8fdf9a60065b 110 MEMCPY(&input[36], secret_16_bytes, 16);
kadonotakashi 0:8fdf9a60065b 111
kadonotakashi 0:8fdf9a60065b 112 /* Save the boot time in 4-us units. Overflow is no problem here. */
kadonotakashi 0:8fdf9a60065b 113 base_time = boot_time * 250000;
kadonotakashi 0:8fdf9a60065b 114 }
kadonotakashi 0:8fdf9a60065b 115
kadonotakashi 0:8fdf9a60065b 116 /**
kadonotakashi 0:8fdf9a60065b 117 * Hook to generate an Initial Sequence Number (ISN) for a new TCP connection.
kadonotakashi 0:8fdf9a60065b 118 *
kadonotakashi 0:8fdf9a60065b 119 * @param local_ip The local IP address.
kadonotakashi 0:8fdf9a60065b 120 * @param local_port The local port number, in host-byte order.
kadonotakashi 0:8fdf9a60065b 121 * @param remote_ip The remote IP address.
kadonotakashi 0:8fdf9a60065b 122 * @param remote_port The remote port number, in host-byte order.
kadonotakashi 0:8fdf9a60065b 123 * @return The ISN to use for the new TCP connection.
kadonotakashi 0:8fdf9a60065b 124 */
kadonotakashi 0:8fdf9a60065b 125
kadonotakashi 0:8fdf9a60065b 126 u32_t
kadonotakashi 0:8fdf9a60065b 127 lwip_hook_tcp_isn(const void *local_ip_ptr, u16_t local_port,
kadonotakashi 0:8fdf9a60065b 128 const void *remote_ip_ptr, u16_t remote_port)
kadonotakashi 0:8fdf9a60065b 129 {
kadonotakashi 0:8fdf9a60065b 130 lwip_md5_context ctx;
kadonotakashi 0:8fdf9a60065b 131 u8_t output[16];
kadonotakashi 0:8fdf9a60065b 132 u32_t isn;
kadonotakashi 0:8fdf9a60065b 133 const ip_addr_t *local_ip = local_ip_ptr;
kadonotakashi 0:8fdf9a60065b 134 const ip_addr_t *remote_ip = remote_ip_ptr;
kadonotakashi 0:8fdf9a60065b 135
kadonotakashi 0:8fdf9a60065b 136 #if LWIP_IPV4 && LWIP_IPV6
kadonotakashi 0:8fdf9a60065b 137 if (IP_IS_V6(local_ip))
kadonotakashi 0:8fdf9a60065b 138 #endif /* LWIP_IPV4 && LWIP_IPV6 */
kadonotakashi 0:8fdf9a60065b 139 #if LWIP_IPV6
kadonotakashi 0:8fdf9a60065b 140 {
kadonotakashi 0:8fdf9a60065b 141 const ip6_addr_t *local_ip6, *remote_ip6;
kadonotakashi 0:8fdf9a60065b 142
kadonotakashi 0:8fdf9a60065b 143 local_ip6 = ip_2_ip6(local_ip);
kadonotakashi 0:8fdf9a60065b 144 remote_ip6 = ip_2_ip6(remote_ip);
kadonotakashi 0:8fdf9a60065b 145
kadonotakashi 0:8fdf9a60065b 146 SMEMCPY(&input[0], &local_ip6->addr, 16);
kadonotakashi 0:8fdf9a60065b 147 SMEMCPY(&input[16], &remote_ip6->addr, 16);
kadonotakashi 0:8fdf9a60065b 148 }
kadonotakashi 0:8fdf9a60065b 149 #endif /* LWIP_IPV6 */
kadonotakashi 0:8fdf9a60065b 150 #if LWIP_IPV4 && LWIP_IPV6
kadonotakashi 0:8fdf9a60065b 151 else
kadonotakashi 0:8fdf9a60065b 152 #endif /* LWIP_IPV4 && LWIP_IPV6 */
kadonotakashi 0:8fdf9a60065b 153 #if LWIP_IPV4
kadonotakashi 0:8fdf9a60065b 154 {
kadonotakashi 0:8fdf9a60065b 155 const ip4_addr_t *local_ip4, *remote_ip4;
kadonotakashi 0:8fdf9a60065b 156
kadonotakashi 0:8fdf9a60065b 157 local_ip4 = ip_2_ip4(local_ip);
kadonotakashi 0:8fdf9a60065b 158 remote_ip4 = ip_2_ip4(remote_ip);
kadonotakashi 0:8fdf9a60065b 159
kadonotakashi 0:8fdf9a60065b 160 /* Represent IPv4 addresses as IPv4-mapped IPv6 addresses, to ensure that
kadonotakashi 0:8fdf9a60065b 161 * the IPv4 and IPv6 address spaces are completely disjoint. */
kadonotakashi 0:8fdf9a60065b 162 memset(&input[0], 0, 10);
kadonotakashi 0:8fdf9a60065b 163 input[10] = 0xff;
kadonotakashi 0:8fdf9a60065b 164 input[11] = 0xff;
kadonotakashi 0:8fdf9a60065b 165 SMEMCPY(&input[12], &local_ip4->addr, 4);
kadonotakashi 0:8fdf9a60065b 166 memset(&input[16], 0, 10);
kadonotakashi 0:8fdf9a60065b 167 input[26] = 0xff;
kadonotakashi 0:8fdf9a60065b 168 input[27] = 0xff;
kadonotakashi 0:8fdf9a60065b 169 SMEMCPY(&input[28], &remote_ip4->addr, 4);
kadonotakashi 0:8fdf9a60065b 170 }
kadonotakashi 0:8fdf9a60065b 171 #endif /* LWIP_IPV4 */
kadonotakashi 0:8fdf9a60065b 172
kadonotakashi 0:8fdf9a60065b 173 input[32] = local_port >> 8;
kadonotakashi 0:8fdf9a60065b 174 input[33] = local_port & 0xff;
kadonotakashi 0:8fdf9a60065b 175 input[34] = remote_port >> 8;
kadonotakashi 0:8fdf9a60065b 176 input[35] = remote_port & 0xff;
kadonotakashi 0:8fdf9a60065b 177
kadonotakashi 0:8fdf9a60065b 178 /* The secret and padding are already filled in. */
kadonotakashi 0:8fdf9a60065b 179
kadonotakashi 0:8fdf9a60065b 180 /* Generate the hash, using MD5. */
kadonotakashi 0:8fdf9a60065b 181 lwip_md5_init(&ctx);
kadonotakashi 0:8fdf9a60065b 182 lwip_md5_starts(&ctx);
kadonotakashi 0:8fdf9a60065b 183 lwip_md5_update(&ctx, input, sizeof(input));
kadonotakashi 0:8fdf9a60065b 184 lwip_md5_finish(&ctx, output);
kadonotakashi 0:8fdf9a60065b 185 lwip_md5_free(&ctx);
kadonotakashi 0:8fdf9a60065b 186
kadonotakashi 0:8fdf9a60065b 187 /* Arbitrarily take the first 32 bits from the generated hash. */
kadonotakashi 0:8fdf9a60065b 188 MEMCPY(&isn, output, sizeof(isn));
kadonotakashi 0:8fdf9a60065b 189
kadonotakashi 0:8fdf9a60065b 190 /* Add the current time in 4-microsecond units. */
kadonotakashi 0:8fdf9a60065b 191 return isn + base_time + sys_now() * 250;
kadonotakashi 0:8fdf9a60065b 192 }