410c8acf |
1 | /* -*-c-*- |
2 | * |
b4e56668 |
3 | * $Id: keyexch.c,v 1.12 2004/04/08 01:36:17 mdw Exp $ |
410c8acf |
4 | * |
5 | * Key exchange protocol |
6 | * |
7 | * (c) 2001 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Trivial IP Encryption (TrIPE). |
13 | * |
14 | * TrIPE is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU General Public License as published by |
16 | * the Free Software Foundation; either version 2 of the License, or |
17 | * (at your option) any later version. |
18 | * |
19 | * TrIPE is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU General Public License |
25 | * along with TrIPE; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
27 | */ |
28 | |
410c8acf |
29 | /*----- Header files ------------------------------------------------------*/ |
30 | |
31 | #include "tripe.h" |
32 | |
737cc271 |
33 | /*----- Brief protocol overview -------------------------------------------* |
34 | * |
35 | * Let %$G$% be a cyclic group; let %$g$% be a generator of %$G$%, and let |
36 | * %$q$% be the order of %$G$%; for a key %$K$%, let %$E_K(\cdot)$% denote |
37 | * application of the symmetric packet protocol to a message; let |
38 | * %$H(\cdot)$% be the random oracle. Let $\alpha \inr \{0,\ldots,q - 1\}$% |
39 | * be Alice's private key; let %$a = g^\alpha$% be her public key; let %$b$% |
40 | * be Bob's public key. |
41 | * |
42 | * At the beginning of the session, Alice chooses |
43 | * |
44 | * %$\rho_A \inr \{0, \ldots q - 1\}$% |
45 | * |
46 | * We also have: |
47 | * |
48 | * %$r_A = g^{\rho_A}$% Alice's challenge |
49 | * %$c_A = H(\cookie{cookie}, r_A)$% Alice's cookie |
50 | * %$v_A = \rho_A \xor H(\cookie{expected-reply}, r_A, r_B, b^{\rho_A})$% |
51 | * Alice's challenge check value |
52 | * %$r_B^\alpha = a^{\rho_B}$% Alice's reply |
53 | * %$K = r_B^{\rho_A} = r_B^{\rho_A} = g^{\rho_A\rho_B}$% |
54 | * Alice and Bob's shared secret key |
55 | * %$w_A = H(\cookie{switch-request}, c_A, c_B)$% |
56 | * Alice's switch request value |
57 | * %$u_A = H(\cookie{switch-confirm}, c_A, c_B)$% |
58 | * Alice's switch confirm value |
59 | * |
60 | * The messages are then: |
61 | * |
62 | * %$\cookie{kx-pre-challenge}, r_A$% |
63 | * Initial greeting. In state @KXS_CHAL@. |
64 | * |
65 | * %$\cookie{kx-cookie}, r_A, c_B$% |
66 | * My table is full but I got your message. |
67 | * |
68 | * %$\cookie{kx-challenge}, r_A, c_B, v_A$% |
69 | * Here's a full challenge for you to answer. |
70 | * |
71 | * %$\cookie{kx-reply}, c_A, c_B, v_A, E_K(r_B^\alpha))$% |
72 | * Challenge accpeted: here's the answer. Commit to my challenge. Move |
73 | * to @KXS_COMMIT@. |
74 | * |
75 | * %$\cookie{kx-switch}, c_A, c_B, E_K(r_B^\alpha, w_A))$% |
76 | * Reply received: here's my reply. Committed; send data; move to |
77 | * @KXS_SWITCH@. |
78 | * |
79 | * %$\cookie{kx-switch-ok}, E_K(u_A))$% |
80 | * Switch received. Committed; send data; move to @KXS_SWITCH@. |
81 | */ |
82 | |
410c8acf |
83 | /*----- Tunable parameters ------------------------------------------------*/ |
84 | |
2de0ad0f |
85 | #define T_VALID MIN(2) /* Challenge validity period */ |
86 | #define T_RETRY SEC(10) /* Challenge retransmit interval */ |
410c8acf |
87 | |
0617b6e7 |
88 | #define ISVALID(kx, now) ((now) < (kx)->t_valid) |
89 | |
90 | /*----- Various utilities -------------------------------------------------*/ |
410c8acf |
91 | |
52c03a2a |
92 | /* --- @hashge@ --- * |
410c8acf |
93 | * |
0617b6e7 |
94 | * Arguments: @HASH_CTX *r@ = pointer to hash context |
52c03a2a |
95 | * @ge *x@ = pointer to group element |
410c8acf |
96 | * |
97 | * Returns: --- |
98 | * |
52c03a2a |
99 | * Use: Adds the hash of a group element to the context. Corrupts |
100 | * @buf_t@. |
410c8acf |
101 | */ |
102 | |
52c03a2a |
103 | static void hashge(HASH_CTX *r, ge *x) |
410c8acf |
104 | { |
105 | buf b; |
0617b6e7 |
106 | buf_init(&b, buf_t, sizeof(buf_t)); |
52c03a2a |
107 | G_TOBUF(gg, &b, x); |
410c8acf |
108 | assert(BOK(&b)); |
0617b6e7 |
109 | HASH(r, BBASE(&b), BLEN(&b)); |
410c8acf |
110 | } |
111 | |
5d418e24 |
112 | /* --- @mpcrypt@ --- * |
113 | * |
114 | * Arguments: @mp *d@ = the destination integer |
115 | * @mp *x@ = the plaintext/ciphertext integer |
116 | * @size_t sz@ = the expected size of the plaintext |
117 | * @const octet *k@ = pointer to key material |
118 | * @size_t ksz@ = size of the key |
119 | * |
120 | * Returns: The encrypted/decrypted integer. |
121 | * |
52c03a2a |
122 | * Use: Encrypts (or decrypts) a multiprecision integer. In fact, |
123 | * the title is a bit of a misnomer: we actually compute |
124 | * %$x \xor H(k)$%, so it's a random oracle thing rather than an |
125 | * encryption thing. |
5d418e24 |
126 | */ |
127 | |
128 | static mp *mpcrypt(mp *d, mp *x, size_t sz, const octet *k, size_t ksz) |
129 | { |
130 | MGF_CTX m; |
131 | |
132 | MGF_INIT(&m, k, ksz, 0); |
133 | mp_storeb(x, buf_t, sz); |
134 | MGF_CRYPT(&m, buf_t, buf_t, sz); |
135 | return (mp_loadb(d, buf_t, sz)); |
136 | } |
137 | |
410c8acf |
138 | /* --- @timer@ --- * |
139 | * |
140 | * Arguments: @struct timeval *tv@ = the current time |
141 | * @void *v@ = pointer to key exchange context |
142 | * |
143 | * Returns: --- |
144 | * |
145 | * Use: Acts when the key exchange timer goes off. |
146 | */ |
147 | |
148 | static void timer(struct timeval *tv, void *v) |
149 | { |
150 | keyexch *kx = v; |
151 | kx->f &= ~KXF_TIMER; |
152 | T( trace(T_KEYEXCH, "keyexch: timer has popped"); ) |
153 | kx_start(kx); |
154 | } |
155 | |
156 | /* --- @settimer@ --- * |
157 | * |
158 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
159 | * @time_t t@ = when to set the timer for |
160 | * |
161 | * Returns: --- |
162 | * |
163 | * Use: Sets the timer for the next key exchange attempt. |
164 | */ |
165 | |
166 | static void settimer(keyexch *kx, time_t t) |
167 | { |
168 | struct timeval tv; |
169 | if (kx->f & KXF_TIMER) |
170 | sel_rmtimer(&kx->t); |
171 | tv.tv_sec = t; |
172 | tv.tv_usec = 0; |
173 | sel_addtimer(&sel, &kx->t, &tv, timer, kx); |
174 | kx->f |= KXF_TIMER; |
175 | } |
176 | |
0617b6e7 |
177 | /*----- Challenge management ----------------------------------------------*/ |
178 | |
179 | /* --- Notes on challenge management --- * |
410c8acf |
180 | * |
0617b6e7 |
181 | * We may get multiple different replies to our key exchange; some will be |
182 | * correct, some inserted by attackers. Up until @KX_THRESH@, all challenges |
183 | * received will be added to the table and given a full response. After |
184 | * @KX_THRESH@ distinct challenges are received, we return only a `cookie': |
185 | * our existing challenge, followed by a hash of the sender's challenge. We |
186 | * do %%\emph{not}%% give a bare challenge a reply slot at this stage. All |
187 | * properly-formed cookies are assigned a table slot: if none is spare, a |
188 | * used slot is randomly selected and destroyed. A cookie always receives a |
189 | * full reply. |
190 | */ |
191 | |
192 | /* --- @kxc_destroy@ --- * |
193 | * |
194 | * Arguments: @kxchal *kxc@ = pointer to the challenge block |
410c8acf |
195 | * |
196 | * Returns: --- |
197 | * |
0617b6e7 |
198 | * Use: Disposes of a challenge block. |
410c8acf |
199 | */ |
200 | |
0617b6e7 |
201 | static void kxc_destroy(kxchal *kxc) |
410c8acf |
202 | { |
0617b6e7 |
203 | if (kxc->f & KXF_TIMER) |
204 | sel_rmtimer(&kxc->t); |
52c03a2a |
205 | G_DESTROY(gg, kxc->c); |
206 | if (kxc->r) G_DESTROY(gg, kxc->r); |
5d418e24 |
207 | mp_drop(kxc->ck); |
0617b6e7 |
208 | ks_drop(kxc->ks); |
209 | DESTROY(kxc); |
210 | } |
410c8acf |
211 | |
0617b6e7 |
212 | /* --- @kxc_stoptimer@ --- * |
213 | * |
214 | * Arguments: @kxchal *kxc@ = pointer to the challenge block |
215 | * |
216 | * Returns: --- |
217 | * |
218 | * Use: Stops the challenge's retry timer from sending messages. |
219 | * Useful when the state machine is in the endgame of the |
220 | * exchange. |
221 | */ |
410c8acf |
222 | |
0617b6e7 |
223 | static void kxc_stoptimer(kxchal *kxc) |
224 | { |
225 | if (kxc->f & KXF_TIMER) |
226 | sel_rmtimer(&kxc->t); |
2de0ad0f |
227 | kxc->f &= ~KXF_TIMER; |
0617b6e7 |
228 | } |
410c8acf |
229 | |
0617b6e7 |
230 | /* --- @kxc_new@ --- * |
231 | * |
232 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
0617b6e7 |
233 | * |
234 | * Returns: A pointer to the challenge block. |
235 | * |
236 | * Use: Returns a pointer to a new challenge block to fill in. |
237 | */ |
410c8acf |
238 | |
0617b6e7 |
239 | static kxchal *kxc_new(keyexch *kx) |
240 | { |
241 | kxchal *kxc; |
242 | unsigned i; |
243 | |
244 | /* --- If we're over reply threshold, discard one at random --- */ |
245 | |
246 | if (kx->nr < KX_NCHAL) |
247 | i = kx->nr++; |
248 | else { |
249 | i = rand_global.ops->range(&rand_global, KX_NCHAL); |
250 | kxc_destroy(kx->r[i]); |
410c8acf |
251 | } |
252 | |
0617b6e7 |
253 | /* --- Fill in the new structure --- */ |
410c8acf |
254 | |
0617b6e7 |
255 | kxc = CREATE(kxchal); |
52c03a2a |
256 | kxc->c = G_CREATE(gg); |
0617b6e7 |
257 | kxc->r = 0; |
52c03a2a |
258 | kxc->ck = MP_NEW; |
0617b6e7 |
259 | kxc->ks = 0; |
260 | kxc->kx = kx; |
261 | kxc->f = 0; |
262 | kx->r[i] = kxc; |
263 | return (kxc); |
264 | } |
410c8acf |
265 | |
0617b6e7 |
266 | /* --- @kxc_bychal@ --- * |
267 | * |
268 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
52c03a2a |
269 | * @ge *c@ = challenge from remote host |
0617b6e7 |
270 | * |
271 | * Returns: Pointer to the challenge block, or null. |
272 | * |
273 | * Use: Finds a challenge block, given its challenge. |
274 | */ |
275 | |
52c03a2a |
276 | static kxchal *kxc_bychal(keyexch *kx, ge *c) |
0617b6e7 |
277 | { |
278 | unsigned i; |
279 | |
280 | for (i = 0; i < kx->nr; i++) { |
52c03a2a |
281 | if (G_EQ(gg, c, kx->r[i]->c)) |
0617b6e7 |
282 | return (kx->r[i]); |
283 | } |
284 | return (0); |
285 | } |
286 | |
287 | /* --- @kxc_byhc@ --- * |
288 | * |
289 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
290 | * @const octet *hc@ = challenge hash from remote host |
291 | * |
292 | * Returns: Pointer to the challenge block, or null. |
293 | * |
294 | * Use: Finds a challenge block, given a hash of its challenge. |
295 | */ |
410c8acf |
296 | |
0617b6e7 |
297 | static kxchal *kxc_byhc(keyexch *kx, const octet *hc) |
298 | { |
299 | unsigned i; |
300 | |
301 | for (i = 0; i < kx->nr; i++) { |
302 | if (memcmp(hc, kx->r[i]->hc, HASHSZ) == 0) |
303 | return (kx->r[i]); |
410c8acf |
304 | } |
0617b6e7 |
305 | return (0); |
306 | } |
307 | |
308 | /* --- @kxc_answer@ --- * |
309 | * |
310 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
311 | * @kxchal *kxc@ = pointer to challenge block |
312 | * |
313 | * Returns: --- |
314 | * |
315 | * Use: Sends a reply to the remote host, according to the data in |
316 | * this challenge block. |
317 | */ |
318 | |
319 | static void kxc_answer(keyexch *kx, kxchal *kxc); |
320 | |
321 | static void kxc_timer(struct timeval *tv, void *v) |
322 | { |
323 | kxchal *kxc = v; |
324 | kxc->f &= ~KXF_TIMER; |
325 | kxc_answer(kxc->kx, kxc); |
326 | } |
327 | |
328 | static void kxc_answer(keyexch *kx, kxchal *kxc) |
329 | { |
330 | stats *st = p_stats(kx->p); |
331 | buf *b = p_txstart(kx->p, MSG_KEYEXCH | (kxc->r ? KX_REPLY : KX_CHAL)); |
332 | struct timeval tv; |
333 | buf bb; |
334 | |
335 | /* --- Build the reply packet --- */ |
336 | |
337 | if (!kxc->r) |
52c03a2a |
338 | G_TOBUF(gg, b, kx->c); |
0617b6e7 |
339 | else |
340 | buf_put(b, kx->hc, HASHSZ); |
341 | buf_put(b, kxc->hc, HASHSZ); |
5d418e24 |
342 | buf_putmp(b, kxc->ck); |
0617b6e7 |
343 | |
344 | /* --- Maybe send an actual reply, if we have one --- */ |
410c8acf |
345 | |
0617b6e7 |
346 | if (!kxc->r) { |
347 | T( trace(T_KEYEXCH, "keyexch: resending challenge to `%s'", |
348 | p_name(kx->p)); ) |
349 | } else { |
350 | T( trace(T_KEYEXCH, "keyexch: sending reply to `%s'", p_name(kx->p)); ) |
351 | buf_init(&bb, buf_i, sizeof(buf_i)); |
52c03a2a |
352 | G_TOBUF(gg, &bb, kxc->r); |
0617b6e7 |
353 | buf_flip(&bb); |
7ed14135 |
354 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_REPLY, &bb, b); |
0617b6e7 |
355 | } |
356 | |
357 | /* --- Update the statistics --- */ |
358 | |
359 | if (BOK(b)) { |
360 | st->n_kxout++; |
361 | st->sz_kxout += BLEN(b); |
362 | p_txend(kx->p); |
363 | } |
364 | |
365 | /* --- Schedule another resend --- */ |
366 | |
367 | if (kxc->f & KXF_TIMER) |
368 | sel_rmtimer(&kxc->t); |
369 | gettimeofday(&tv, 0); |
370 | tv.tv_sec += T_RETRY; |
371 | sel_addtimer(&sel, &kxc->t, &tv, kxc_timer, kxc); |
372 | kxc->f |= KXF_TIMER; |
373 | } |
374 | |
375 | /*----- Individual message handlers ---------------------------------------*/ |
376 | |
377 | /* --- @getreply@ --- * |
378 | * |
379 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
52c03a2a |
380 | * @ge *c@ = a challenge |
5d418e24 |
381 | * @mp *ck@ = the supplied expected-reply check value |
0617b6e7 |
382 | * |
383 | * Returns: A pointer to the reply, or null if the reply-hash was wrong. |
384 | * |
385 | * Use: Computes replies to challenges. |
386 | */ |
387 | |
52c03a2a |
388 | static ge *getreply(keyexch *kx, ge *c, mp *ck) |
0617b6e7 |
389 | { |
52c03a2a |
390 | ge *r = G_CREATE(gg); |
391 | ge *y = G_CREATE(gg); |
392 | mp *a = MP_NEW; |
0617b6e7 |
393 | HASH_CTX h; |
5d418e24 |
394 | octet buf[HASHSZ]; |
395 | int ok; |
0617b6e7 |
396 | |
52c03a2a |
397 | G_EXP(gg, r, c, kpriv); |
0617b6e7 |
398 | HASH_INIT(&h); |
399 | HASH_STRING(&h, "tripe-expected-reply"); |
52c03a2a |
400 | hashge(&h, c); |
401 | hashge(&h, kx->c); |
402 | hashge(&h, r); |
0617b6e7 |
403 | HASH_DONE(&h, buf); |
5d418e24 |
404 | |
52c03a2a |
405 | a = mpcrypt(MP_NEW, ck, mp_octets(gg->r), buf, sizeof(buf)); |
0617b6e7 |
406 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
52c03a2a |
407 | trace(T_CRYPTO, "crypto: computed reply = %s", gestr(gg, r)); |
0617b6e7 |
408 | trace_block(T_CRYPTO, "crypto: computed reply hash", buf, HASHSZ); |
5d418e24 |
409 | trace(T_CRYPTO, "crypto: recovered log = %s", mpstr(a)); |
0617b6e7 |
410 | })) |
52c03a2a |
411 | G_EXP(gg, y, gg->g, a); |
412 | ok = G_EQ(gg, y, c); |
5d418e24 |
413 | if (!ok) { |
414 | a_warn("invalid expected-reply check from `%s'", p_name(kx->p)); |
415 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
52c03a2a |
416 | trace(T_CRYPTO, "crypto: computed challenge = %s", gestr(gg, y)); |
5d418e24 |
417 | })) |
52c03a2a |
418 | G_DESTROY(gg, r); |
419 | r = 0; |
0617b6e7 |
420 | } |
5d418e24 |
421 | mp_drop(a); |
52c03a2a |
422 | G_DESTROY(gg, y); |
423 | return (r); |
0617b6e7 |
424 | } |
425 | |
426 | /* --- @dochallenge@ --- * |
427 | * |
428 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
429 | * @unsigned msg@ = message code for the packet |
430 | * @buf *b@ = buffer containing the packet |
431 | * |
432 | * Returns: Zero if OK, nonzero if the packet was rejected. |
433 | * |
434 | * Use: Processes a packet containing a challenge. |
435 | */ |
436 | |
437 | static int dochallenge(keyexch *kx, unsigned msg, buf *b) |
438 | { |
52c03a2a |
439 | ge *c = G_CREATE(gg); |
440 | mp *ck = MP_NEW; |
5d418e24 |
441 | const octet *hc = 0; |
0617b6e7 |
442 | kxchal *kxc; |
443 | HASH_CTX h; |
5d418e24 |
444 | octet buf[HASHSZ]; |
0617b6e7 |
445 | |
446 | /* --- Ensure that we're in a sensible state --- */ |
447 | |
448 | if (kx->s != KXS_CHAL) { |
449 | a_warn("unexpected challenge from `%s'", p_name(kx->p)); |
450 | goto bad; |
451 | } |
452 | |
453 | /* --- Unpack the packet --- */ |
454 | |
52c03a2a |
455 | if (G_FROMBUF(gg, b, c) || |
0617b6e7 |
456 | (msg >= KX_COOKIE && (hc = buf_get(b, HASHSZ)) == 0) || |
5d418e24 |
457 | (msg >= KX_CHAL && (ck = buf_getmp(b)) == 0) || |
0617b6e7 |
458 | BLEFT(b)) { |
459 | a_warn("malformed packet from `%s'", p_name(kx->p)); |
460 | goto bad; |
461 | } |
462 | |
463 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
52c03a2a |
464 | trace(T_CRYPTO, "crypto: challenge = %s", gestr(gg, c)); |
0617b6e7 |
465 | if (hc) trace_block(T_CRYPTO, "crypto: cookie", hc, HASHSZ); |
5d418e24 |
466 | if (ck) trace(T_CRYPTO, "crypto: check value = %s", mpstr(ck)); |
0617b6e7 |
467 | })) |
468 | |
469 | /* --- First, handle a bare challenge --- * |
470 | * |
471 | * If the table is heavily loaded, just emit a cookie and return. |
472 | */ |
473 | |
474 | if (!hc && kx->nr >= KX_THRESH) { |
475 | T( trace(T_KEYEXCH, "keyexch: too many challenges -- sending cookie"); ) |
476 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_COOKIE); |
52c03a2a |
477 | G_TOBUF(gg, b, kx->c); |
0617b6e7 |
478 | HASH_INIT(&h); |
479 | HASH_STRING(&h, "tripe-cookie"); |
52c03a2a |
480 | hashge(&h, c); |
0617b6e7 |
481 | HASH_DONE(&h, buf_get(b, HASHSZ)); |
482 | p_txend(kx->p); |
483 | goto tidy; |
484 | } |
485 | |
486 | /* --- Discard a packet with an invalid cookie --- */ |
487 | |
488 | if (hc && memcmp(hc, kx->hc, HASHSZ) != 0) { |
489 | a_warn("incorrect cookie from `%s'", p_name(kx->p)); |
490 | goto bad; |
491 | } |
492 | |
493 | /* --- Find a challenge block for this packet --- * |
410c8acf |
494 | * |
0617b6e7 |
495 | * If there isn't one already, create a new one. |
410c8acf |
496 | */ |
497 | |
0617b6e7 |
498 | if ((kxc = kxc_bychal(kx, c)) == 0) { |
499 | size_t x, y, z; |
52c03a2a |
500 | ge *r; |
0617b6e7 |
501 | |
502 | /* --- Be careful here --- * |
503 | * |
504 | * If this is a full challenge, and it's the first time I've seen it, I |
505 | * want to be able to throw it away before committing a table entry to |
506 | * it. |
507 | */ |
508 | |
5d418e24 |
509 | if (!ck) |
0617b6e7 |
510 | kxc = kxc_new(kx); |
511 | else { |
5d418e24 |
512 | if ((r = getreply(kx, c, ck)) == 0) |
0617b6e7 |
513 | goto bad; |
514 | kxc = kxc_new(kx); |
515 | kxc->r = r; |
410c8acf |
516 | } |
52c03a2a |
517 | kxc->c = G_CREATE(gg); |
518 | G_COPY(gg, kxc->c, c); |
0617b6e7 |
519 | |
520 | /* --- Work out the cookie for this challenge --- */ |
521 | |
522 | HASH_INIT(&h); |
523 | HASH_STRING(&h, "tripe-cookie"); |
52c03a2a |
524 | hashge(&h, kxc->c); |
0617b6e7 |
525 | HASH_DONE(&h, kxc->hc); |
526 | |
527 | /* --- Compute the expected-reply hash --- */ |
528 | |
529 | HASH_INIT(&h); |
530 | HASH_STRING(&h, "tripe-expected-reply"); |
52c03a2a |
531 | hashge(&h, kx->c); |
532 | hashge(&h, kxc->c); |
533 | hashge(&h, kx->rx); |
5d418e24 |
534 | HASH_DONE(&h, buf); |
52c03a2a |
535 | kxc->ck = mpcrypt(MP_NEW, kx->alpha, mp_octets(gg->r), |
5d418e24 |
536 | buf, sizeof(buf)); |
0617b6e7 |
537 | |
538 | /* --- Work out the shared key --- */ |
539 | |
52c03a2a |
540 | r = G_CREATE(gg); |
541 | G_EXP(gg, r, c, kx->alpha); |
0617b6e7 |
542 | |
543 | /* --- Compute the switch messages --- */ |
544 | |
545 | HASH_INIT(&h); HASH_STRING(&h, "tripe-switch-request"); |
52c03a2a |
546 | hashge(&h, kx->c); hashge(&h, kxc->c); |
0617b6e7 |
547 | HASH_DONE(&h, kxc->hswrq_out); |
548 | HASH_INIT(&h); HASH_STRING(&h, "tripe-switch-confirm"); |
52c03a2a |
549 | hashge(&h, kx->c); hashge(&h, kxc->c); |
0617b6e7 |
550 | HASH_DONE(&h, kxc->hswok_out); |
551 | |
552 | HASH_INIT(&h); HASH_STRING(&h, "tripe-switch-request"); |
52c03a2a |
553 | hashge(&h, kxc->c); hashge(&h, kx->c); |
0617b6e7 |
554 | HASH_DONE(&h, kxc->hswrq_in); |
555 | HASH_INIT(&h); HASH_STRING(&h, "tripe-switch-confirm"); |
52c03a2a |
556 | hashge(&h, kxc->c); hashge(&h, kx->c); |
0617b6e7 |
557 | HASH_DONE(&h, kxc->hswok_in); |
558 | |
559 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
560 | trace_block(T_CRYPTO, "crypto: computed cookie", kxc->hc, HASHSZ); |
5d418e24 |
561 | trace_block(T_CRYPTO, "crypto: expected-reply hash", |
562 | buf, HASHSZ); |
563 | trace(T_CRYPTO, "crypto: my reply check = %s", mpstr(kxc->ck)); |
52c03a2a |
564 | trace(T_CRYPTO, "crypto: shared secret = %s", gestr(gg, r)); |
0617b6e7 |
565 | trace_block(T_CRYPTO, "crypto: outbound switch request", |
566 | kxc->hswrq_out, HASHSZ); |
567 | trace_block(T_CRYPTO, "crypto: outbound switch confirm", |
568 | kxc->hswok_out, HASHSZ); |
569 | trace_block(T_CRYPTO, "crypto: inbound switch request", |
570 | kxc->hswrq_in, HASHSZ); |
571 | trace_block(T_CRYPTO, "crypto: inbound switch confirm", |
572 | kxc->hswok_in, HASHSZ); |
573 | })) |
574 | |
575 | /* --- Create a new symmetric keyset --- */ |
576 | |
577 | buf_init(b, buf_o, sizeof(buf_o)); |
52c03a2a |
578 | G_TOBUF(gg, b, kx->c); x = BLEN(b); |
579 | G_TOBUF(gg, b, kxc->c); y = BLEN(b); |
580 | G_TOBUF(gg, b, r); z = BLEN(b); |
0617b6e7 |
581 | assert(BOK(b)); |
582 | |
9466fafa |
583 | kxc->ks = ks_gen(BBASE(b), x, y, z, kx->p); |
52c03a2a |
584 | G_DESTROY(gg, r); |
410c8acf |
585 | } |
586 | |
0617b6e7 |
587 | /* --- Answer the challenge if we need to --- */ |
410c8acf |
588 | |
5d418e24 |
589 | if (ck && !kxc->r) { |
52c03a2a |
590 | ge *r; |
5d418e24 |
591 | if ((r = getreply(kx, c, ck)) == 0) |
0617b6e7 |
592 | goto bad; |
593 | kxc->r = r; |
410c8acf |
594 | } |
0617b6e7 |
595 | |
596 | kxc_answer(kx, kxc); |
597 | |
598 | /* --- Tidy up and go home --- */ |
599 | |
600 | tidy: |
52c03a2a |
601 | G_DESTROY(gg, c); |
5d418e24 |
602 | mp_drop(ck); |
0617b6e7 |
603 | return (0); |
604 | |
605 | bad: |
52c03a2a |
606 | G_DESTROY(gg, c); |
5d418e24 |
607 | mp_drop(ck); |
0617b6e7 |
608 | return (-1); |
410c8acf |
609 | } |
610 | |
0617b6e7 |
611 | /* --- @resend@ --- * |
410c8acf |
612 | * |
613 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
410c8acf |
614 | * |
615 | * Returns: --- |
616 | * |
0617b6e7 |
617 | * Use: Sends the next message for a key exchange. |
410c8acf |
618 | */ |
619 | |
0617b6e7 |
620 | static void resend(keyexch *kx) |
410c8acf |
621 | { |
0617b6e7 |
622 | kxchal *kxc; |
623 | buf bb; |
624 | stats *st = p_stats(kx->p); |
410c8acf |
625 | buf *b; |
626 | |
0617b6e7 |
627 | switch (kx->s) { |
628 | case KXS_CHAL: |
00e64b67 |
629 | T( trace(T_KEYEXCH, "keyexch: sending prechallenge to `%s'", |
630 | p_name(kx->p)); ) |
0617b6e7 |
631 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_PRECHAL); |
52c03a2a |
632 | G_TOBUF(gg, b, kx->c); |
0617b6e7 |
633 | break; |
634 | case KXS_COMMIT: |
00e64b67 |
635 | T( trace(T_KEYEXCH, "keyexch: sending switch request to `%s'", |
636 | p_name(kx->p)); ) |
0617b6e7 |
637 | kxc = kx->r[0]; |
638 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_SWITCH); |
639 | buf_put(b, kx->hc, HASHSZ); |
640 | buf_put(b, kxc->hc, HASHSZ); |
641 | buf_init(&bb, buf_i, sizeof(buf_i)); |
52c03a2a |
642 | G_TOBUF(gg, &bb, kxc->r); |
0617b6e7 |
643 | buf_put(&bb, kxc->hswrq_out, HASHSZ); |
644 | buf_flip(&bb); |
7ed14135 |
645 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCH, &bb, b); |
0617b6e7 |
646 | break; |
647 | case KXS_SWITCH: |
00e64b67 |
648 | T( trace(T_KEYEXCH, "keyexch: sending switch confirmation to `%s'", |
0617b6e7 |
649 | p_name(kx->p)); ) |
650 | kxc = kx->r[0]; |
651 | b = p_txstart(kx->p, MSG_KEYEXCH | KX_SWITCHOK); |
652 | buf_init(&bb, buf_i, sizeof(buf_i)); |
653 | buf_put(&bb, kxc->hswok_out, HASHSZ); |
654 | buf_flip(&bb); |
7ed14135 |
655 | ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCHOK, &bb, b); |
0617b6e7 |
656 | break; |
657 | default: |
658 | abort(); |
410c8acf |
659 | } |
0617b6e7 |
660 | |
661 | if (BOK(b)) { |
662 | st->n_kxout++; |
663 | st->sz_kxout += BLEN(b); |
664 | p_txend(kx->p); |
665 | } |
666 | |
667 | if (kx->s < KXS_SWITCH) |
668 | settimer(kx, time(0) + T_RETRY); |
410c8acf |
669 | } |
670 | |
0617b6e7 |
671 | /* --- @matchreply@ --- * |
672 | * |
673 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
7ed14135 |
674 | * @unsigned ty@ = type of incoming message |
0617b6e7 |
675 | * @const octet *hc_in@ = a hash of his challenge |
676 | * @const octet *hc_out@ = a hash of my challenge (cookie) |
5d418e24 |
677 | * @mp *ck@ = his expected-reply hash (optional) |
0617b6e7 |
678 | * @buf *b@ = encrypted remainder of the packet |
679 | * |
680 | * Returns: A pointer to the challenge block if OK, or null on failure. |
681 | * |
682 | * Use: Checks a reply or switch packet, ensuring that its contents |
683 | * are sensible and correct. If they are, @*b@ is set to point |
684 | * to the remainder of the encrypted data, and the correct |
685 | * challenge is returned. |
686 | */ |
687 | |
7ed14135 |
688 | static kxchal *matchreply(keyexch *kx, unsigned ty, const octet *hc_in, |
5d418e24 |
689 | const octet *hc_out, mp *ck, buf *b) |
410c8acf |
690 | { |
0617b6e7 |
691 | kxchal *kxc; |
692 | buf bb; |
52c03a2a |
693 | ge *r = 0; |
0617b6e7 |
694 | |
695 | /* --- Check the plaintext portions of the data --- */ |
696 | |
697 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
698 | trace_block(T_CRYPTO, "crypto: challenge", hc_in, HASHSZ); |
699 | trace_block(T_CRYPTO, "crypto: cookie", hc_out, HASHSZ); |
5d418e24 |
700 | if (ck) trace(T_CRYPTO, "crypto: check value = %s", mpstr(ck)); |
0617b6e7 |
701 | })) |
702 | if (memcmp(hc_out, kx->hc, HASHSZ) != 0) { |
703 | a_warn("incorrect cookie from `%s'", p_name(kx->p)); |
704 | goto bad; |
705 | } |
706 | if ((kxc = kxc_byhc(kx, hc_in)) == 0) { |
707 | a_warn("received reply for unknown challenge from `%s'", p_name(kx->p)); |
708 | goto bad; |
709 | } |
410c8acf |
710 | |
0617b6e7 |
711 | /* --- Maybe compute a reply for the challenge --- */ |
712 | |
713 | if (!kxc->r) { |
5d418e24 |
714 | if (!ck) { |
0617b6e7 |
715 | a_warn("unexpected switch request from `%s'", p_name(kx->p)); |
716 | goto bad; |
717 | } |
5d418e24 |
718 | if ((r = getreply(kx, kxc->c, ck)) == 0) |
0617b6e7 |
719 | goto bad; |
720 | kxc->r = r; |
721 | r = 0; |
722 | } |
723 | |
724 | /* --- Decrypt the rest of the packet --- */ |
725 | |
726 | buf_init(&bb, buf_o, sizeof(buf_o)); |
7ed14135 |
727 | if (ks_decrypt(kxc->ks, ty, b, &bb)) { |
0617b6e7 |
728 | a_warn("failed to decrypt reply from `%s'", p_name(kx->p)); |
729 | goto bad; |
410c8acf |
730 | } |
0617b6e7 |
731 | buf_init(b, BBASE(&bb), BLEN(&bb)); |
52c03a2a |
732 | r = G_CREATE(gg); |
733 | if (G_FROMBUF(gg, b, r)) { |
0617b6e7 |
734 | a_warn("invalid reply packet from `%s'", p_name(kx->p)); |
735 | goto bad; |
736 | } |
737 | IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { |
52c03a2a |
738 | trace(T_CRYPTO, "crypto: reply = %s", gestr(gg, r)); |
0617b6e7 |
739 | })) |
52c03a2a |
740 | if (!G_EQ(gg, r, kx->rx)) { |
0617b6e7 |
741 | a_warn("incorrect reply from `%s'", p_name(kx->p)); |
742 | goto bad; |
743 | } |
744 | |
745 | /* --- Done --- */ |
746 | |
52c03a2a |
747 | G_DESTROY(gg, r); |
0617b6e7 |
748 | return (kxc); |
749 | |
750 | bad: |
52c03a2a |
751 | if (r) G_DESTROY(gg, r); |
0617b6e7 |
752 | return (0); |
410c8acf |
753 | } |
754 | |
0617b6e7 |
755 | /* --- @commit@ --- * |
410c8acf |
756 | * |
757 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
0617b6e7 |
758 | * @kxchal *kxc@ = pointer to challenge to commit to |
410c8acf |
759 | * |
760 | * Returns: --- |
761 | * |
0617b6e7 |
762 | * Use: Commits to a particular challenge as being the `right' one, |
763 | * since a reply has arrived for it. |
410c8acf |
764 | */ |
765 | |
0617b6e7 |
766 | static void commit(keyexch *kx, kxchal *kxc) |
410c8acf |
767 | { |
0617b6e7 |
768 | unsigned i; |
410c8acf |
769 | |
0617b6e7 |
770 | for (i = 0; i < kx->nr; i++) { |
771 | if (kx->r[i] != kxc) |
772 | kxc_destroy(kx->r[i]); |
773 | } |
774 | kx->r[0] = kxc; |
775 | kx->nr = 1; |
776 | kxc_stoptimer(kxc); |
777 | ksl_link(kx->ks, kxc->ks); |
410c8acf |
778 | } |
779 | |
0617b6e7 |
780 | /* --- @doreply@ --- * |
410c8acf |
781 | * |
782 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
0617b6e7 |
783 | * @buf *b@ = buffer containing packet |
410c8acf |
784 | * |
0617b6e7 |
785 | * Returns: Zero if OK, nonzero if the packet was rejected. |
410c8acf |
786 | * |
0617b6e7 |
787 | * Use: Handles a reply packet. This doesn't handle the various |
788 | * switch packets: they're rather too different. |
410c8acf |
789 | */ |
790 | |
0617b6e7 |
791 | static int doreply(keyexch *kx, buf *b) |
410c8acf |
792 | { |
5d418e24 |
793 | const octet *hc_in, *hc_out; |
794 | mp *ck = 0; |
0617b6e7 |
795 | kxchal *kxc; |
796 | |
797 | if (kx->s != KXS_CHAL && kx->s != KXS_COMMIT) { |
798 | a_warn("unexpected reply from `%s'", p_name(kx->p)); |
799 | goto bad; |
800 | } |
801 | if ((hc_in = buf_get(b, HASHSZ)) == 0 || |
802 | (hc_out = buf_get(b, HASHSZ)) == 0 || |
5d418e24 |
803 | (ck = buf_getmp(b)) == 0) { |
0617b6e7 |
804 | a_warn("invalid reply packet from `%s'", p_name(kx->p)); |
805 | goto bad; |
806 | } |
7ed14135 |
807 | if ((kxc = matchreply(kx, MSG_KEYEXCH | KX_REPLY, |
808 | hc_in, hc_out, ck, b)) == 0) |
0617b6e7 |
809 | goto bad; |
810 | if (BLEFT(b)) { |
811 | a_warn("invalid reply packet from `%s'", p_name(kx->p)); |
812 | goto bad; |
813 | } |
814 | if (kx->s == KXS_CHAL) { |
815 | commit(kx, kxc); |
816 | kx->s = KXS_COMMIT; |
817 | } |
818 | resend(kx); |
819 | return (0); |
820 | |
821 | bad: |
5d418e24 |
822 | mp_drop(ck); |
0617b6e7 |
823 | return (-1); |
410c8acf |
824 | } |
825 | |
0617b6e7 |
826 | /* --- @doswitch@ --- * |
410c8acf |
827 | * |
0617b6e7 |
828 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
829 | * @buf *b@ = pointer to buffer containing packet |
410c8acf |
830 | * |
0617b6e7 |
831 | * Returns: Zero if OK, nonzero if the packet was rejected. |
410c8acf |
832 | * |
0617b6e7 |
833 | * Use: Handles a reply with a switch request bolted onto it. |
410c8acf |
834 | */ |
835 | |
0617b6e7 |
836 | static int doswitch(keyexch *kx, buf *b) |
410c8acf |
837 | { |
0617b6e7 |
838 | const octet *hc_in, *hc_out, *hswrq; |
839 | kxchal *kxc; |
410c8acf |
840 | |
0617b6e7 |
841 | if ((hc_in = buf_get(b, HASHSZ)) == 0 || |
842 | (hc_out = buf_get(b, HASHSZ)) == 0) { |
843 | a_warn("invalid switch request from `%s'", p_name(kx->p)); |
844 | goto bad; |
410c8acf |
845 | } |
7ed14135 |
846 | if ((kxc = matchreply(kx, MSG_KEYEXCH | KX_SWITCH, |
847 | hc_in, hc_out, 0, b)) == 0) |
0617b6e7 |
848 | goto bad; |
849 | if ((hswrq = buf_get(b, HASHSZ)) == 0 || BLEFT(b)) { |
850 | a_warn("invalid switch request from `%s'", p_name(kx->p)); |
851 | goto bad; |
852 | } |
853 | IF_TRACING(T_KEYEXCH, { |
854 | trace_block(T_CRYPTO, "crypto: switch request hash", hswrq, HASHSZ); |
855 | }) |
856 | if (memcmp(hswrq, kxc->hswrq_in, HASHSZ) != 0) { |
857 | a_warn("incorrect switch request hash from `%s'", p_name(kx->p)); |
858 | goto bad; |
859 | } |
860 | switch (kx->s) { |
861 | case KXS_CHAL: |
862 | commit(kx, kxc); |
863 | case KXS_COMMIT: |
864 | ks_activate(kxc->ks); |
865 | settimer(kx, ks_tregen(kxc->ks)); |
866 | kx->s = KXS_SWITCH; |
867 | break; |
868 | } |
869 | resend(kx); |
870 | return (0); |
871 | |
872 | bad: |
873 | return (-1); |
410c8acf |
874 | } |
875 | |
0617b6e7 |
876 | /* --- @doswitchok@ --- * |
877 | * |
878 | * Arguments: @keyexch *kx@ = pointer to key exchange block |
879 | * @buf *b@ = pointer to buffer containing packet |
880 | * |
881 | * Returns: Zero if OK, nonzero if the packet was rejected. |
882 | * |
883 | * Use: Handles a reply with a switch request bolted onto it. |
884 | */ |
885 | |
886 | static int doswitchok(keyexch *kx, buf *b) |
410c8acf |
887 | { |
0617b6e7 |
888 | const octet *hswok; |
889 | kxchal *kxc; |
890 | buf bb; |
410c8acf |
891 | |
0617b6e7 |
892 | if (kx->s < KXS_COMMIT) { |
893 | a_warn("unexpected switch confirmation from `%s'", p_name(kx->p)); |
894 | goto bad; |
410c8acf |
895 | } |
0617b6e7 |
896 | kxc = kx->r[0]; |
897 | buf_init(&bb, buf_o, sizeof(buf_o)); |
7ed14135 |
898 | if (ks_decrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCHOK, b, &bb)) { |
0617b6e7 |
899 | a_warn("failed to decrypt switch confirmation from `%s'", p_name(kx->p)); |
900 | goto bad; |
901 | } |
902 | buf_init(b, BBASE(&bb), BLEN(&bb)); |
903 | if ((hswok = buf_get(b, HASHSZ)) == 0 || BLEFT(b)) { |
904 | a_warn("invalid switch confirmation from `%s'", p_name(kx->p)); |
905 | goto bad; |
906 | } |
907 | IF_TRACING(T_KEYEXCH, { |
908 | trace_block(T_CRYPTO, "crypto: switch confirmation hash", hswok, HASHSZ); |
909 | }) |
910 | if (memcmp(hswok, kxc->hswok_in, HASHSZ) != 0) { |
911 | a_warn("incorrect switch confirmation hash from `%s'", p_name(kx->p)); |
912 | goto bad; |
913 | } |
914 | if (kx->s < KXS_SWITCH) { |
915 | ks_activate(kxc->ks); |
916 | settimer(kx, ks_tregen(kxc->ks)); |
917 | kx->s = KXS_SWITCH; |
918 | } |
919 | return (0); |
920 | |
921 | bad: |
922 | return (-1); |
923 | } |
924 | |
925 | /*----- Main code ---------------------------------------------------------*/ |
926 | |
927 | /* --- @stop@ --- * |
928 | * |
929 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
930 | * |
931 | * Returns: --- |
932 | * |
933 | * Use: Stops a key exchange dead in its tracks. Throws away all of |
934 | * the context information. The context is left in an |
935 | * inconsistent state. The only functions which understand this |
936 | * state are @kx_free@ and @kx_init@ (which cause it internally |
937 | * it), and @start@ (which expects it to be the prevailing |
938 | * state). |
939 | */ |
940 | |
941 | static void stop(keyexch *kx) |
942 | { |
943 | unsigned i; |
944 | |
00e64b67 |
945 | if (kx->f & KXF_DEAD) |
946 | return; |
947 | |
0617b6e7 |
948 | if (kx->f & KXF_TIMER) |
949 | sel_rmtimer(&kx->t); |
950 | for (i = 0; i < kx->nr; i++) |
951 | kxc_destroy(kx->r[i]); |
952 | mp_drop(kx->alpha); |
52c03a2a |
953 | G_DESTROY(gg, kx->c); |
954 | G_DESTROY(gg, kx->rx); |
00e64b67 |
955 | kx->t_valid = 0; |
956 | kx->f |= KXF_DEAD; |
957 | kx->f &= ~KXF_TIMER; |
0617b6e7 |
958 | } |
959 | |
960 | /* --- @start@ --- * |
961 | * |
962 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
963 | * @time_t now@ = the current time |
964 | * |
965 | * Returns: --- |
966 | * |
967 | * Use: Starts a new key exchange with the peer. The context must be |
968 | * in the bizarre state left by @stop@ or @kx_init@. |
969 | */ |
970 | |
971 | static void start(keyexch *kx, time_t now) |
972 | { |
973 | HASH_CTX h; |
974 | |
00e64b67 |
975 | assert(kx->f & KXF_DEAD); |
976 | |
977 | kx->f &= ~KXF_DEAD; |
0617b6e7 |
978 | kx->nr = 0; |
52c03a2a |
979 | kx->alpha = mprand_range(MP_NEW, gg->r, &rand_global, 0); |
980 | kx->c = G_CREATE(gg); G_EXP(gg, kx->c, gg->g, kx->alpha); |
981 | kx->rx = G_CREATE(gg); G_EXP(gg, kx->rx, kx->kpub, kx->alpha); |
0617b6e7 |
982 | kx->s = KXS_CHAL; |
983 | kx->t_valid = now + T_VALID; |
984 | |
985 | HASH_INIT(&h); |
986 | HASH_STRING(&h, "tripe-cookie"); |
52c03a2a |
987 | hashge(&h, kx->c); |
0617b6e7 |
988 | HASH_DONE(&h, kx->hc); |
989 | |
990 | IF_TRACING(T_KEYEXCH, { |
991 | trace(T_KEYEXCH, "keyexch: creating new challenge"); |
992 | IF_TRACING(T_CRYPTO, { |
993 | trace(T_CRYPTO, "crypto: secret = %s", mpstr(kx->alpha)); |
52c03a2a |
994 | trace(T_CRYPTO, "crypto: challenge = %s", gestr(gg, kx->c)); |
995 | trace(T_CRYPTO, "crypto: expected response = %s", gestr(gg, kx->rx)); |
0617b6e7 |
996 | trace_block(T_CRYPTO, "crypto: challenge cookie", kx->hc, HASHSZ); |
997 | }) |
998 | }) |
410c8acf |
999 | } |
1000 | |
00e64b67 |
1001 | /* --- @checkpub@ --- * |
1002 | * |
1003 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
1004 | * |
1005 | * Returns: Zero if OK, nonzero if the peer's public key has expired. |
1006 | * |
1007 | * Use: Deactivates the key-exchange until the peer acquires a new |
1008 | * public key. |
1009 | */ |
1010 | |
1011 | static int checkpub(keyexch *kx) |
1012 | { |
1013 | time_t now; |
1014 | if (kx->f & KXF_DEAD) |
1015 | return (-1); |
1016 | now = time(0); |
1017 | if (KEY_EXPIRED(now, kx->texp_kpub)) { |
1018 | stop(kx); |
1019 | a_warn("public key for `%s' has expired", p_name(kx->p)); |
52c03a2a |
1020 | G_COPY(gg, kx->kpub, gg->i); |
00e64b67 |
1021 | kx->f &= ~KXF_PUBKEY; |
1022 | return (-1); |
1023 | } |
1024 | return (0); |
1025 | } |
1026 | |
0617b6e7 |
1027 | /* --- @kx_start@ --- * |
410c8acf |
1028 | * |
1029 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
410c8acf |
1030 | * |
1031 | * Returns: --- |
1032 | * |
0617b6e7 |
1033 | * Use: Stimulates a key exchange. If a key exchage is in progress, |
1034 | * a new challenge is sent (unless the quiet timer forbids |
1035 | * this); if no exchange is in progress, one is commenced. |
410c8acf |
1036 | */ |
1037 | |
0617b6e7 |
1038 | void kx_start(keyexch *kx) |
410c8acf |
1039 | { |
1040 | time_t now = time(0); |
410c8acf |
1041 | |
00e64b67 |
1042 | if (checkpub(kx)) |
1043 | return; |
0617b6e7 |
1044 | if (!ISVALID(kx, now)) { |
1045 | stop(kx); |
1046 | start(kx, now); |
410c8acf |
1047 | } |
0617b6e7 |
1048 | resend(kx); |
1049 | } |
1050 | |
1051 | /* --- @kx_message@ --- * |
1052 | * |
1053 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
1054 | * @unsigned msg@ = the message code |
1055 | * @buf *b@ = pointer to buffer containing the packet |
1056 | * |
1057 | * Returns: --- |
1058 | * |
1059 | * Use: Reads a packet containing key exchange messages and handles |
1060 | * it. |
1061 | */ |
1062 | |
1063 | void kx_message(keyexch *kx, unsigned msg, buf *b) |
1064 | { |
1065 | time_t now = time(0); |
1066 | stats *st = p_stats(kx->p); |
1067 | size_t sz = BSZ(b); |
1068 | int rc; |
1069 | |
1070 | #ifndef NTRACE |
1071 | static const char *const pkname[] = { |
1072 | "prechallenge", "cookie", "challenge", |
1073 | "reply", "switch request", "switch confirmation" |
1074 | }; |
1075 | #endif |
1076 | |
00e64b67 |
1077 | if (checkpub(kx)) |
1078 | return; |
1079 | |
0617b6e7 |
1080 | if (!ISVALID(kx, now)) { |
1081 | stop(kx); |
1082 | start(kx, now); |
410c8acf |
1083 | } |
0617b6e7 |
1084 | |
1085 | T( trace(T_KEYEXCH, "keyexch: processing %s packet from `%s'", |
1086 | msg < KX_NMSG ? pkname[msg] : "unknown", p_name(kx->p)); ) |
1087 | |
1088 | switch (msg) { |
1089 | case KX_PRECHAL: |
1090 | case KX_COOKIE: |
1091 | case KX_CHAL: |
1092 | rc = dochallenge(kx, msg, b); |
1093 | break; |
1094 | case KX_REPLY: |
1095 | rc = doreply(kx, b); |
1096 | break; |
1097 | case KX_SWITCH: |
1098 | rc = doswitch(kx, b); |
1099 | break; |
1100 | case KX_SWITCHOK: |
1101 | rc = doswitchok(kx, b); |
1102 | break; |
1103 | default: |
1104 | a_warn("unexpected key exchange message type %u from `%p'", |
1105 | p_name(kx->p)); |
1106 | rc = -1; |
1107 | break; |
410c8acf |
1108 | } |
410c8acf |
1109 | |
0617b6e7 |
1110 | if (rc) |
1111 | st->n_reject++; |
1112 | else { |
1113 | st->n_kxin++; |
1114 | st->sz_kxin += sz; |
1115 | } |
410c8acf |
1116 | } |
1117 | |
1118 | /* --- @kx_free@ --- * |
1119 | * |
1120 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
1121 | * |
1122 | * Returns: --- |
1123 | * |
1124 | * Use: Frees everything in a key exchange context. |
1125 | */ |
1126 | |
1127 | void kx_free(keyexch *kx) |
1128 | { |
0617b6e7 |
1129 | stop(kx); |
52c03a2a |
1130 | G_DESTROY(gg, kx->kpub); |
410c8acf |
1131 | } |
1132 | |
1133 | /* --- @kx_newkeys@ --- * |
1134 | * |
1135 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
1136 | * |
1137 | * Returns: --- |
1138 | * |
1139 | * Use: Informs the key exchange module that its keys may have |
1140 | * changed. If fetching the new keys fails, the peer will be |
1141 | * destroyed, we log messages and struggle along with the old |
1142 | * keys. |
1143 | */ |
1144 | |
1145 | void kx_newkeys(keyexch *kx) |
1146 | { |
52c03a2a |
1147 | if (km_getpubkey(p_name(kx->p), kx->kpub, &kx->texp_kpub)) |
410c8acf |
1148 | return; |
00e64b67 |
1149 | kx->f |= KXF_PUBKEY; |
1150 | if ((kx->f & KXF_DEAD) || kx->s != KXS_SWITCH) { |
410c8acf |
1151 | T( trace(T_KEYEXCH, "keyexch: restarting key negotiation with `%s'", |
1152 | p_name(kx->p)); ) |
00e64b67 |
1153 | stop(kx); |
1154 | start(kx, time(0)); |
1155 | resend(kx); |
410c8acf |
1156 | } |
1157 | } |
1158 | |
1159 | /* --- @kx_init@ --- * |
1160 | * |
1161 | * Arguments: @keyexch *kx@ = pointer to key exchange context |
1162 | * @peer *p@ = pointer to peer context |
1163 | * @keyset **ks@ = pointer to keyset list |
1164 | * |
1165 | * Returns: Zero if OK, nonzero if it failed. |
1166 | * |
1167 | * Use: Initializes a key exchange module. The module currently |
1168 | * contains no keys, and will attempt to initiate a key |
1169 | * exchange. |
1170 | */ |
1171 | |
1172 | int kx_init(keyexch *kx, peer *p, keyset **ks) |
1173 | { |
1174 | kx->ks = ks; |
1175 | kx->p = p; |
52c03a2a |
1176 | kx->kpub = G_CREATE(gg); |
1177 | if (km_getpubkey(p_name(p), kx->kpub, &kx->texp_kpub)) { |
1178 | G_DESTROY(gg, kx->kpub); |
410c8acf |
1179 | return (-1); |
52c03a2a |
1180 | } |
00e64b67 |
1181 | kx->f = KXF_DEAD | KXF_PUBKEY; |
0617b6e7 |
1182 | start(kx, time(0)); |
1183 | resend(kx); |
410c8acf |
1184 | return (0); |
1185 | } |
1186 | |
1187 | /*----- That's all, folks -------------------------------------------------*/ |