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-rw-r--r--lwip/src/netif/ppp/mppe.c412
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diff --git a/lwip/src/netif/ppp/mppe.c b/lwip/src/netif/ppp/mppe.c
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+/*
+ * mppe.c - interface MPPE to the PPP code.
+ *
+ * By Frank Cusack <fcusack@fcusack.com>.
+ * Copyright (c) 2002,2003,2004 Google, Inc.
+ * All rights reserved.
+ *
+ * License:
+ * Permission to use, copy, modify, and distribute this software and its
+ * documentation is hereby granted, provided that the above copyright
+ * notice appears in all copies. This software is provided without any
+ * warranty, express or implied.
+ *
+ * Changelog:
+ * 08/12/05 - Matt Domsch <Matt_Domsch@dell.com>
+ * Only need extra skb padding on transmit, not receive.
+ * 06/18/04 - Matt Domsch <Matt_Domsch@dell.com>, Oleg Makarenko <mole@quadra.ru>
+ * Use Linux kernel 2.6 arc4 and sha1 routines rather than
+ * providing our own.
+ * 2/15/04 - TS: added #include <version.h> and testing for Kernel
+ * version before using
+ * MOD_DEC_USAGE_COUNT/MOD_INC_USAGE_COUNT which are
+ * deprecated in 2.6
+ */
+
+#include "netif/ppp/ppp_opts.h"
+#if PPP_SUPPORT && MPPE_SUPPORT /* don't build if not configured for use in lwipopts.h */
+
+#include <string.h>
+
+#include "lwip/err.h"
+
+#include "netif/ppp/ppp_impl.h"
+#include "netif/ppp/ccp.h"
+#include "netif/ppp/mppe.h"
+#include "netif/ppp/pppdebug.h"
+#include "netif/ppp/pppcrypt.h"
+
+#define SHA1_SIGNATURE_SIZE 20
+
+/* ppp_mppe_state.bits definitions */
+#define MPPE_BIT_A 0x80 /* Encryption table were (re)inititalized */
+#define MPPE_BIT_B 0x40 /* MPPC only (not implemented) */
+#define MPPE_BIT_C 0x20 /* MPPC only (not implemented) */
+#define MPPE_BIT_D 0x10 /* This is an encrypted frame */
+
+#define MPPE_BIT_FLUSHED MPPE_BIT_A
+#define MPPE_BIT_ENCRYPTED MPPE_BIT_D
+
+#define MPPE_BITS(p) ((p)[0] & 0xf0)
+#define MPPE_CCOUNT(p) ((((p)[0] & 0x0f) << 8) + (p)[1])
+#define MPPE_CCOUNT_SPACE 0x1000 /* The size of the ccount space */
+
+#define MPPE_OVHD 2 /* MPPE overhead/packet */
+#define SANITY_MAX 1600 /* Max bogon factor we will tolerate */
+
+/*
+ * Perform the MPPE rekey algorithm, from RFC 3078, sec. 7.3.
+ * Well, not what's written there, but rather what they meant.
+ */
+static void mppe_rekey(ppp_mppe_state * state, int initial_key)
+{
+ lwip_sha1_context sha1_ctx;
+ u8_t sha1_digest[SHA1_SIGNATURE_SIZE];
+
+ /*
+ * Key Derivation, from RFC 3078, RFC 3079.
+ * Equivalent to Get_Key() for MS-CHAP as described in RFC 3079.
+ */
+ lwip_sha1_init(&sha1_ctx);
+ lwip_sha1_starts(&sha1_ctx);
+ lwip_sha1_update(&sha1_ctx, state->master_key, state->keylen);
+ lwip_sha1_update(&sha1_ctx, mppe_sha1_pad1, SHA1_PAD_SIZE);
+ lwip_sha1_update(&sha1_ctx, state->session_key, state->keylen);
+ lwip_sha1_update(&sha1_ctx, mppe_sha1_pad2, SHA1_PAD_SIZE);
+ lwip_sha1_finish(&sha1_ctx, sha1_digest);
+ lwip_sha1_free(&sha1_ctx);
+ MEMCPY(state->session_key, sha1_digest, state->keylen);
+
+ if (!initial_key) {
+ lwip_arc4_init(&state->arc4);
+ lwip_arc4_setup(&state->arc4, sha1_digest, state->keylen);
+ lwip_arc4_crypt(&state->arc4, state->session_key, state->keylen);
+ lwip_arc4_free(&state->arc4);
+ }
+ if (state->keylen == 8) {
+ /* See RFC 3078 */
+ state->session_key[0] = 0xd1;
+ state->session_key[1] = 0x26;
+ state->session_key[2] = 0x9e;
+ }
+ lwip_arc4_init(&state->arc4);
+ lwip_arc4_setup(&state->arc4, state->session_key, state->keylen);
+}
+
+/*
+ * Set key, used by MSCHAP before mppe_init() is actually called by CCP so we
+ * don't have to keep multiple copies of keys.
+ */
+void mppe_set_key(ppp_pcb *pcb, ppp_mppe_state *state, u8_t *key) {
+ LWIP_UNUSED_ARG(pcb);
+ MEMCPY(state->master_key, key, MPPE_MAX_KEY_LEN);
+}
+
+/*
+ * Initialize (de)compressor state.
+ */
+void
+mppe_init(ppp_pcb *pcb, ppp_mppe_state *state, u8_t options)
+{
+#if PPP_DEBUG
+ const u8_t *debugstr = (const u8_t*)"mppe_comp_init";
+ if (&pcb->mppe_decomp == state) {
+ debugstr = (const u8_t*)"mppe_decomp_init";
+ }
+#endif /* PPP_DEBUG */
+
+ /* Save keys. */
+ MEMCPY(state->session_key, state->master_key, sizeof(state->master_key));
+
+ if (options & MPPE_OPT_128)
+ state->keylen = 16;
+ else if (options & MPPE_OPT_40)
+ state->keylen = 8;
+ else {
+ PPPDEBUG(LOG_DEBUG, ("%s[%d]: unknown key length\n", debugstr,
+ pcb->netif->num));
+ lcp_close(pcb, "MPPE required but peer negotiation failed");
+ return;
+ }
+ if (options & MPPE_OPT_STATEFUL)
+ state->stateful = 1;
+
+ /* Generate the initial session key. */
+ mppe_rekey(state, 1);
+
+#if PPP_DEBUG
+ {
+ int i;
+ char mkey[sizeof(state->master_key) * 2 + 1];
+ char skey[sizeof(state->session_key) * 2 + 1];
+
+ PPPDEBUG(LOG_DEBUG, ("%s[%d]: initialized with %d-bit %s mode\n",
+ debugstr, pcb->netif->num, (state->keylen == 16) ? 128 : 40,
+ (state->stateful) ? "stateful" : "stateless"));
+
+ for (i = 0; i < (int)sizeof(state->master_key); i++)
+ sprintf(mkey + i * 2, "%02x", state->master_key[i]);
+ for (i = 0; i < (int)sizeof(state->session_key); i++)
+ sprintf(skey + i * 2, "%02x", state->session_key[i]);
+ PPPDEBUG(LOG_DEBUG,
+ ("%s[%d]: keys: master: %s initial session: %s\n",
+ debugstr, pcb->netif->num, mkey, skey));
+ }
+#endif /* PPP_DEBUG */
+
+ /*
+ * Initialize the coherency count. The initial value is not specified
+ * in RFC 3078, but we can make a reasonable assumption that it will
+ * start at 0. Setting it to the max here makes the comp/decomp code
+ * do the right thing (determined through experiment).
+ */
+ state->ccount = MPPE_CCOUNT_SPACE - 1;
+
+ /*
+ * Note that even though we have initialized the key table, we don't
+ * set the FLUSHED bit. This is contrary to RFC 3078, sec. 3.1.
+ */
+ state->bits = MPPE_BIT_ENCRYPTED;
+}
+
+/*
+ * We received a CCP Reset-Request (actually, we are sending a Reset-Ack),
+ * tell the compressor to rekey. Note that we MUST NOT rekey for
+ * every CCP Reset-Request; we only rekey on the next xmit packet.
+ * We might get multiple CCP Reset-Requests if our CCP Reset-Ack is lost.
+ * So, rekeying for every CCP Reset-Request is broken as the peer will not
+ * know how many times we've rekeyed. (If we rekey and THEN get another
+ * CCP Reset-Request, we must rekey again.)
+ */
+void mppe_comp_reset(ppp_pcb *pcb, ppp_mppe_state *state)
+{
+ LWIP_UNUSED_ARG(pcb);
+ state->bits |= MPPE_BIT_FLUSHED;
+}
+
+/*
+ * Compress (encrypt) a packet.
+ * It's strange to call this a compressor, since the output is always
+ * MPPE_OVHD + 2 bytes larger than the input.
+ */
+err_t
+mppe_compress(ppp_pcb *pcb, ppp_mppe_state *state, struct pbuf **pb, u16_t protocol)
+{
+ struct pbuf *n, *np;
+ u8_t *pl;
+ err_t err;
+
+ LWIP_UNUSED_ARG(pcb);
+
+ /* TCP stack requires that we don't change the packet payload, therefore we copy
+ * the whole packet before encryption.
+ */
+ np = pbuf_alloc(PBUF_RAW, MPPE_OVHD + sizeof(protocol) + (*pb)->tot_len, PBUF_RAM);
+ if (!np) {
+ return ERR_MEM;
+ }
+
+ /* Hide MPPE header + protocol */
+ pbuf_remove_header(np, MPPE_OVHD + sizeof(protocol));
+
+ if ((err = pbuf_copy(np, *pb)) != ERR_OK) {
+ pbuf_free(np);
+ return err;
+ }
+
+ /* Reveal MPPE header + protocol */
+ pbuf_add_header(np, MPPE_OVHD + sizeof(protocol));
+
+ *pb = np;
+ pl = (u8_t*)np->payload;
+
+ state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
+ PPPDEBUG(LOG_DEBUG, ("mppe_compress[%d]: ccount %d\n", pcb->netif->num, state->ccount));
+ /* FIXME: use PUT* macros */
+ pl[0] = state->ccount>>8;
+ pl[1] = state->ccount;
+
+ if (!state->stateful || /* stateless mode */
+ ((state->ccount & 0xff) == 0xff) || /* "flag" packet */
+ (state->bits & MPPE_BIT_FLUSHED)) { /* CCP Reset-Request */
+ /* We must rekey */
+ if (state->stateful) {
+ PPPDEBUG(LOG_DEBUG, ("mppe_compress[%d]: rekeying\n", pcb->netif->num));
+ }
+ mppe_rekey(state, 0);
+ state->bits |= MPPE_BIT_FLUSHED;
+ }
+ pl[0] |= state->bits;
+ state->bits &= ~MPPE_BIT_FLUSHED; /* reset for next xmit */
+ pl += MPPE_OVHD;
+
+ /* Add protocol */
+ /* FIXME: add PFC support */
+ pl[0] = protocol >> 8;
+ pl[1] = protocol;
+
+ /* Hide MPPE header */
+ pbuf_remove_header(np, MPPE_OVHD);
+
+ /* Encrypt packet */
+ for (n = np; n != NULL; n = n->next) {
+ lwip_arc4_crypt(&state->arc4, (u8_t*)n->payload, n->len);
+ if (n->tot_len == n->len) {
+ break;
+ }
+ }
+
+ /* Reveal MPPE header */
+ pbuf_add_header(np, MPPE_OVHD);
+
+ return ERR_OK;
+}
+
+/*
+ * We received a CCP Reset-Ack. Just ignore it.
+ */
+void mppe_decomp_reset(ppp_pcb *pcb, ppp_mppe_state *state)
+{
+ LWIP_UNUSED_ARG(pcb);
+ LWIP_UNUSED_ARG(state);
+ return;
+}
+
+/*
+ * Decompress (decrypt) an MPPE packet.
+ */
+err_t
+mppe_decompress(ppp_pcb *pcb, ppp_mppe_state *state, struct pbuf **pb)
+{
+ struct pbuf *n0 = *pb, *n;
+ u8_t *pl;
+ u16_t ccount;
+ u8_t flushed;
+
+ /* MPPE Header */
+ if (n0->len < MPPE_OVHD) {
+ PPPDEBUG(LOG_DEBUG,
+ ("mppe_decompress[%d]: short pkt (%d)\n",
+ pcb->netif->num, n0->len));
+ state->sanity_errors += 100;
+ goto sanity_error;
+ }
+
+ pl = (u8_t*)n0->payload;
+ flushed = MPPE_BITS(pl) & MPPE_BIT_FLUSHED;
+ ccount = MPPE_CCOUNT(pl);
+ PPPDEBUG(LOG_DEBUG, ("mppe_decompress[%d]: ccount %d\n",
+ pcb->netif->num, ccount));
+
+ /* sanity checks -- terminate with extreme prejudice */
+ if (!(MPPE_BITS(pl) & MPPE_BIT_ENCRYPTED)) {
+ PPPDEBUG(LOG_DEBUG,
+ ("mppe_decompress[%d]: ENCRYPTED bit not set!\n",
+ pcb->netif->num));
+ state->sanity_errors += 100;
+ goto sanity_error;
+ }
+ if (!state->stateful && !flushed) {
+ PPPDEBUG(LOG_DEBUG, ("mppe_decompress[%d]: FLUSHED bit not set in "
+ "stateless mode!\n", pcb->netif->num));
+ state->sanity_errors += 100;
+ goto sanity_error;
+ }
+ if (state->stateful && ((ccount & 0xff) == 0xff) && !flushed) {
+ PPPDEBUG(LOG_DEBUG, ("mppe_decompress[%d]: FLUSHED bit not set on "
+ "flag packet!\n", pcb->netif->num));
+ state->sanity_errors += 100;
+ goto sanity_error;
+ }
+
+ /*
+ * Check the coherency count.
+ */
+
+ if (!state->stateful) {
+ /* Discard late packet */
+ if ((ccount - state->ccount) % MPPE_CCOUNT_SPACE > MPPE_CCOUNT_SPACE / 2) {
+ state->sanity_errors++;
+ goto sanity_error;
+ }
+
+ /* RFC 3078, sec 8.1. Rekey for every packet. */
+ while (state->ccount != ccount) {
+ mppe_rekey(state, 0);
+ state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
+ }
+ } else {
+ /* RFC 3078, sec 8.2. */
+ if (!state->discard) {
+ /* normal state */
+ state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
+ if (ccount != state->ccount) {
+ /*
+ * (ccount > state->ccount)
+ * Packet loss detected, enter the discard state.
+ * Signal the peer to rekey (by sending a CCP Reset-Request).
+ */
+ state->discard = 1;
+ ccp_resetrequest(pcb);
+ return ERR_BUF;
+ }
+ } else {
+ /* discard state */
+ if (!flushed) {
+ /* ccp.c will be silent (no additional CCP Reset-Requests). */
+ return ERR_BUF;
+ } else {
+ /* Rekey for every missed "flag" packet. */
+ while ((ccount & ~0xff) !=
+ (state->ccount & ~0xff)) {
+ mppe_rekey(state, 0);
+ state->ccount =
+ (state->ccount +
+ 256) % MPPE_CCOUNT_SPACE;
+ }
+
+ /* reset */
+ state->discard = 0;
+ state->ccount = ccount;
+ /*
+ * Another problem with RFC 3078 here. It implies that the
+ * peer need not send a Reset-Ack packet. But RFC 1962
+ * requires it. Hopefully, M$ does send a Reset-Ack; even
+ * though it isn't required for MPPE synchronization, it is
+ * required to reset CCP state.
+ */
+ }
+ }
+ if (flushed)
+ mppe_rekey(state, 0);
+ }
+
+ /* Hide MPPE header */
+ pbuf_remove_header(n0, MPPE_OVHD);
+
+ /* Decrypt the packet. */
+ for (n = n0; n != NULL; n = n->next) {
+ lwip_arc4_crypt(&state->arc4, (u8_t*)n->payload, n->len);
+ if (n->tot_len == n->len) {
+ break;
+ }
+ }
+
+ /* good packet credit */
+ state->sanity_errors >>= 1;
+
+ return ERR_OK;
+
+sanity_error:
+ if (state->sanity_errors >= SANITY_MAX) {
+ /*
+ * Take LCP down if the peer is sending too many bogons.
+ * We don't want to do this for a single or just a few
+ * instances since it could just be due to packet corruption.
+ */
+ lcp_close(pcb, "Too many MPPE errors");
+ }
+ return ERR_BUF;
+}
+
+#endif /* PPP_SUPPORT && MPPE_SUPPORT */
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