1/*
2 * Gather (Read) entire SSL2 records from socket into buffer.
3 *
4 * This Source Code Form is subject to the terms of the Mozilla Public
5 * License, v. 2.0. If a copy of the MPL was not distributed with this
6 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
7#include "cert.h"
8#include "ssl.h"
9#include "sslimpl.h"
10#include "sslproto.h"
11
12/* Forward static declarations */
13static SECStatus ssl2_HandleV3HandshakeRecord(sslSocket *ss);
14
15/*
16** Gather a single record of data from the receiving stream. This code
17** first gathers the header (2 or 3 bytes long depending on the value of
18** the most significant bit in the first byte) then gathers up the data
19** for the record into gs->buf. This code handles non-blocking I/O
20** and is to be called multiple times until ss->sec.recordLen != 0.
21** This function decrypts the gathered record in place, in gs_buf.
22 *
23 * Caller must hold RecvBufLock.
24 *
25 * Returns +1 when it has gathered a complete SSLV2 record.
26 * Returns  0 if it hits EOF.
27 * Returns -1 (SECFailure)    on any error
28 * Returns -2 (SECWouldBlock) when it gathers an SSL v3 client hello header.
29**
30** The SSL2 Gather State machine has 4 states:
31** GS_INIT   - Done reading in previous record.  Haven't begun to read in
32**             next record.  When ssl2_GatherData is called with the machine
33**             in this state, the machine will attempt to read the first 3
34**             bytes of the SSL2 record header, and will advance the state
35**             to GS_HEADER.
36**
37** GS_HEADER - The machine is in this state while waiting for the completion
38**             of the first 3 bytes of the SSL2 record.  When complete, the
39**             machine will compute the remaining unread length of this record
40**             and will initiate a read of that many bytes.  The machine will
41**             advance to one of two states, depending on whether the record
42**             is encrypted (GS_MAC), or unencrypted (GS_DATA).
43**
44** GS_MAC    - The machine is in this state while waiting for the remainder
45**             of the SSL2 record to be read in.  When the read is completed,
46**             the machine checks the record for valid length, decrypts it,
47**             and checks and discards the MAC, then advances to GS_INIT.
48**
49** GS_DATA   - The machine is in this state while waiting for the remainder
50**             of the unencrypted SSL2 record to be read in.  Upon completion,
51**             the machine advances to the GS_INIT state and returns the data.
52*/
53int
54ssl2_GatherData(sslSocket *ss, sslGather *gs, int flags)
55{
56    unsigned char *  bp;
57    unsigned char *  pBuf;
58    int              nb, err, rv;
59
60    PORT_Assert( ss->opt.noLocks || ssl_HaveRecvBufLock(ss) );
61
62    if (gs->state == GS_INIT) {
63	/* Initialize gathering engine */
64	gs->state         = GS_HEADER;
65	gs->remainder     = 3;
66	gs->count         = 3;
67	gs->offset        = 0;
68	gs->recordLen     = 0;
69	gs->recordPadding = 0;
70	gs->hdr[2]        = 0;
71
72	gs->writeOffset   = 0;
73	gs->readOffset    = 0;
74    }
75    if (gs->encrypted) {
76	PORT_Assert(ss->sec.hash != 0);
77    }
78
79    pBuf = gs->buf.buf;
80    for (;;) {
81	SSL_TRC(30, ("%d: SSL[%d]: gather state %d (need %d more)",
82		     SSL_GETPID(), ss->fd, gs->state, gs->remainder));
83	bp = ((gs->state != GS_HEADER) ? pBuf : gs->hdr) + gs->offset;
84	nb = ssl_DefRecv(ss, bp, gs->remainder, flags);
85	if (nb > 0) {
86	    PRINT_BUF(60, (ss, "raw gather data:", bp, nb));
87	}
88	if (nb == 0) {
89	    /* EOF */
90	    SSL_TRC(30, ("%d: SSL[%d]: EOF", SSL_GETPID(), ss->fd));
91	    rv = 0;
92	    break;
93	}
94	if (nb < 0) {
95	    SSL_DBG(("%d: SSL[%d]: recv error %d", SSL_GETPID(), ss->fd,
96		     PR_GetError()));
97	    rv = SECFailure;
98	    break;
99	}
100
101	gs->offset    += nb;
102	gs->remainder -= nb;
103
104	if (gs->remainder > 0) {
105	    continue;
106	}
107
108	/* Probably finished this piece */
109	switch (gs->state) {
110	case GS_HEADER:
111	    if (!SSL3_ALL_VERSIONS_DISABLED(&ss->vrange) && !ss->firstHsDone) {
112
113		PORT_Assert( ss->opt.noLocks || ssl_Have1stHandshakeLock(ss) );
114
115		/* If this looks like an SSL3 handshake record,
116		** and we're expecting an SSL2 Hello message from our peer,
117		** handle it here.
118		*/
119		if (gs->hdr[0] == content_handshake) {
120		    if ((ss->nextHandshake == ssl2_HandleClientHelloMessage) ||
121			(ss->nextHandshake == ssl2_HandleServerHelloMessage)) {
122			rv = ssl2_HandleV3HandshakeRecord(ss);
123			if (rv == SECFailure) {
124			    return SECFailure;
125			}
126		    }
127		    /* XXX_1	The call stack to here is:
128		     * ssl_Do1stHandshake -> ssl_GatherRecord1stHandshake ->
129		     *			ssl2_GatherRecord -> here.
130		     * We want to return all the way out to ssl_Do1stHandshake,
131		     * and have it call ssl_GatherRecord1stHandshake again.
132		     * ssl_GatherRecord1stHandshake will call
133		     * ssl3_GatherCompleteHandshake when it is called again.
134		     *
135		     * Returning SECWouldBlock here causes
136		     * ssl_GatherRecord1stHandshake to return without clearing
137		     * ss->handshake, ensuring that ssl_Do1stHandshake will
138		     * call it again immediately.
139		     *
140		     * If we return 1 here, ssl_GatherRecord1stHandshake will
141		     * clear ss->handshake before returning, and thus will not
142		     * be called again by ssl_Do1stHandshake.
143		     */
144		    return SECWouldBlock;
145		} else if (gs->hdr[0] == content_alert) {
146		    if (ss->nextHandshake == ssl2_HandleServerHelloMessage) {
147			/* XXX This is a hack.  We're assuming that any failure
148			 * XXX on the client hello is a failure to match
149			 * XXX ciphers.
150			 */
151			PORT_SetError(SSL_ERROR_NO_CYPHER_OVERLAP);
152			return SECFailure;
153		    }
154		}
155	    }
156
157	    /* we've got the first 3 bytes.  The header may be two or three. */
158	    if (gs->hdr[0] & 0x80) {
159		/* This record has a 2-byte header, and no padding */
160		gs->count = ((gs->hdr[0] & 0x7f) << 8) | gs->hdr[1];
161		gs->recordPadding = 0;
162	    } else {
163		/* This record has a 3-byte header that is all read in now. */
164		gs->count = ((gs->hdr[0] & 0x3f) << 8) | gs->hdr[1];
165	    /*  is_escape =  (gs->hdr[0] & 0x40) != 0; */
166		gs->recordPadding = gs->hdr[2];
167	    }
168	    if (!gs->count) {
169		PORT_SetError(SSL_ERROR_RX_RECORD_TOO_LONG);
170		goto cleanup;
171	    }
172
173	    if (gs->count > gs->buf.space) {
174		err = sslBuffer_Grow(&gs->buf, gs->count);
175		if (err) {
176		    return err;
177		}
178		pBuf = gs->buf.buf;
179	    }
180
181
182	    if (gs->hdr[0] & 0x80) {
183	    	/* we've already read in the first byte of the body.
184		** Put it into the buffer.
185		*/
186		pBuf[0]        = gs->hdr[2];
187		gs->offset    = 1;
188		gs->remainder = gs->count - 1;
189	    } else {
190		gs->offset    = 0;
191		gs->remainder = gs->count;
192	    }
193
194	    if (gs->encrypted) {
195		gs->state     = GS_MAC;
196		gs->recordLen = gs->count - gs->recordPadding
197		                          - ss->sec.hash->length;
198	    } else {
199		gs->state     = GS_DATA;
200		gs->recordLen = gs->count;
201	    }
202
203	    break;
204
205
206	case GS_MAC:
207	    /* Have read in entire rest of the ciphertext.
208	    ** Check for valid length.
209	    ** Decrypt it.
210	    ** Check the MAC.
211	    */
212	    PORT_Assert(gs->encrypted);
213
214	  {
215	    unsigned int     macLen;
216	    int              nout;
217	    unsigned char    mac[SSL_MAX_MAC_BYTES];
218
219	    ssl_GetSpecReadLock(ss); /**********************************/
220
221	    /* If this is a stream cipher, blockSize will be 1,
222	     * and this test will always be false.
223	     * If this is a block cipher, this will detect records
224	     * that are not a multiple of the blocksize in length.
225	     */
226	    if (gs->count & (ss->sec.blockSize - 1)) {
227		/* This is an error. Sender is misbehaving */
228		SSL_DBG(("%d: SSL[%d]: sender, count=%d blockSize=%d",
229			 SSL_GETPID(), ss->fd, gs->count,
230			 ss->sec.blockSize));
231		PORT_SetError(SSL_ERROR_BAD_BLOCK_PADDING);
232		rv = SECFailure;
233		goto spec_locked_done;
234	    }
235	    PORT_Assert(gs->count == gs->offset);
236
237	    if (gs->offset == 0) {
238		rv = 0;			/* means EOF. */
239		goto spec_locked_done;
240	    }
241
242	    /* Decrypt the portion of data that we just received.
243	    ** Decrypt it in place.
244	    */
245	    rv = (*ss->sec.dec)(ss->sec.readcx, pBuf, &nout, gs->offset,
246			     pBuf, gs->offset);
247	    if (rv != SECSuccess) {
248		goto spec_locked_done;
249	    }
250
251
252	    /* Have read in all the MAC portion of record
253	    **
254	    ** Prepare MAC by resetting it and feeding it the shared secret
255	    */
256	    macLen = ss->sec.hash->length;
257	    if (gs->offset >= macLen) {
258		PRUint32           sequenceNumber = ss->sec.rcvSequence++;
259		unsigned char    seq[4];
260
261		seq[0] = (unsigned char) (sequenceNumber >> 24);
262		seq[1] = (unsigned char) (sequenceNumber >> 16);
263		seq[2] = (unsigned char) (sequenceNumber >> 8);
264		seq[3] = (unsigned char) (sequenceNumber);
265
266		(*ss->sec.hash->begin)(ss->sec.hashcx);
267		(*ss->sec.hash->update)(ss->sec.hashcx, ss->sec.rcvSecret.data,
268				        ss->sec.rcvSecret.len);
269		(*ss->sec.hash->update)(ss->sec.hashcx, pBuf + macLen,
270				        gs->offset - macLen);
271		(*ss->sec.hash->update)(ss->sec.hashcx, seq, 4);
272		(*ss->sec.hash->end)(ss->sec.hashcx, mac, &macLen, macLen);
273
274		PORT_Assert(macLen == ss->sec.hash->length);
275
276		ssl_ReleaseSpecReadLock(ss);  /******************************/
277
278		if (NSS_SecureMemcmp(mac, pBuf, macLen) != 0) {
279		    /* MAC's didn't match... */
280		    SSL_DBG(("%d: SSL[%d]: mac check failed, seq=%d",
281			     SSL_GETPID(), ss->fd, ss->sec.rcvSequence));
282		    PRINT_BUF(1, (ss, "computed mac:", mac, macLen));
283		    PRINT_BUF(1, (ss, "received mac:", pBuf, macLen));
284		    PORT_SetError(SSL_ERROR_BAD_MAC_READ);
285		    rv = SECFailure;
286		    goto cleanup;
287		}
288	    } else {
289		ssl_ReleaseSpecReadLock(ss);  /******************************/
290	    }
291
292	    if (gs->recordPadding + macLen <= gs->offset) {
293		gs->recordOffset  = macLen;
294		gs->readOffset    = macLen;
295		gs->writeOffset   = gs->offset - gs->recordPadding;
296		rv = 1;
297	    } else {
298		PORT_SetError(SSL_ERROR_BAD_BLOCK_PADDING);
299cleanup:
300		/* nothing in the buffer any more. */
301		gs->recordOffset  = 0;
302		gs->readOffset    = 0;
303	    	gs->writeOffset   = 0;
304		rv = SECFailure;
305	    }
306
307	    gs->recordLen     = gs->writeOffset - gs->readOffset;
308	    gs->recordPadding = 0;	/* forget we did any padding. */
309	    gs->state = GS_INIT;
310
311
312	    if (rv > 0) {
313		PRINT_BUF(50, (ss, "recv clear record:",
314		               pBuf + gs->recordOffset, gs->recordLen));
315	    }
316	    return rv;
317
318spec_locked_done:
319	    ssl_ReleaseSpecReadLock(ss);
320	    return rv;
321	  }
322
323	case GS_DATA:
324	    /* Have read in all the DATA portion of record */
325
326	    gs->recordOffset  = 0;
327	    gs->readOffset    = 0;
328	    gs->writeOffset   = gs->offset;
329	    PORT_Assert(gs->recordLen == gs->writeOffset - gs->readOffset);
330	    gs->recordLen     = gs->offset;
331	    gs->recordPadding = 0;
332	    gs->state         = GS_INIT;
333
334	    ++ss->sec.rcvSequence;
335
336	    PRINT_BUF(50, (ss, "recv clear record:",
337	                   pBuf + gs->recordOffset, gs->recordLen));
338	    return 1;
339
340	}	/* end switch gs->state */
341    }		/* end gather loop. */
342    return rv;
343}
344
345/*
346** Gather a single record of data from the receiving stream. This code
347** first gathers the header (2 or 3 bytes long depending on the value of
348** the most significant bit in the first byte) then gathers up the data
349** for the record into the readBuf. This code handles non-blocking I/O
350** and is to be called multiple times until ss->sec.recordLen != 0.
351 *
352 * Returns +1 when it has gathered a complete SSLV2 record.
353 * Returns  0 if it hits EOF.
354 * Returns -1 (SECFailure)    on any error
355 * Returns -2 (SECWouldBlock)
356 *
357 * Called by ssl_GatherRecord1stHandshake in sslcon.c,
358 * and by DoRecv in sslsecur.c
359 * Caller must hold RecvBufLock.
360 */
361int
362ssl2_GatherRecord(sslSocket *ss, int flags)
363{
364    return ssl2_GatherData(ss, &ss->gs, flags);
365}
366
367/*
368 * Returns +1 when it has gathered a complete SSLV2 record.
369 * Returns  0 if it hits EOF.
370 * Returns -1 (SECFailure)    on any error
371 * Returns -2 (SECWouldBlock)
372 *
373 * Called from SocksStartGather in sslsocks.c
374 * Caller must hold RecvBufLock.
375 */
376int
377ssl2_StartGatherBytes(sslSocket *ss, sslGather *gs, unsigned int count)
378{
379    int rv;
380
381    PORT_Assert( ss->opt.noLocks || ssl_HaveRecvBufLock(ss) );
382    gs->state     = GS_DATA;
383    gs->remainder = count;
384    gs->count     = count;
385    gs->offset    = 0;
386    if (count > gs->buf.space) {
387	rv = sslBuffer_Grow(&gs->buf, count);
388	if (rv) {
389	    return rv;
390	}
391    }
392    return ssl2_GatherData(ss, gs, 0);
393}
394
395/* Caller should hold RecvBufLock. */
396SECStatus
397ssl_InitGather(sslGather *gs)
398{
399    SECStatus status;
400
401    gs->state = GS_INIT;
402    gs->writeOffset = 0;
403    gs->readOffset  = 0;
404    gs->dtlsPacketOffset = 0;
405    gs->dtlsPacket.len = 0;
406    status = sslBuffer_Grow(&gs->buf, 4096);
407    return status;
408}
409
410/* Caller must hold RecvBufLock. */
411void
412ssl_DestroyGather(sslGather *gs)
413{
414    if (gs) {	/* the PORT_*Free functions check for NULL pointers. */
415	PORT_ZFree(gs->buf.buf, gs->buf.space);
416	PORT_Free(gs->inbuf.buf);
417	PORT_Free(gs->dtlsPacket.buf);
418    }
419}
420
421/* Caller must hold RecvBufLock. */
422static SECStatus
423ssl2_HandleV3HandshakeRecord(sslSocket *ss)
424{
425    SECStatus           rv;
426
427    PORT_Assert( ss->opt.noLocks || ssl_HaveRecvBufLock(ss) );
428    PORT_Assert( ss->opt.noLocks || ssl_Have1stHandshakeLock(ss) );
429
430    /* We've read in 3 bytes, there are 2 more to go in an ssl3 header. */
431    ss->gs.remainder         = 2;
432    ss->gs.count             = 0;
433
434    /* Clearing these handshake pointers ensures that
435     * ssl_Do1stHandshake won't call ssl2_HandleMessage when we return.
436     */
437    ss->nextHandshake     = 0;
438    ss->securityHandshake = 0;
439
440    /* Setting ss->version to an SSL 3.x value will cause
441    ** ssl_GatherRecord1stHandshake to invoke ssl3_GatherCompleteHandshake()
442    ** the next time it is called.
443    **/
444    rv = ssl3_NegotiateVersion(ss, SSL_LIBRARY_VERSION_MAX_SUPPORTED,
445			       PR_TRUE);
446    if (rv != SECSuccess) {
447	return rv;
448    }
449
450    ss->sec.send         = ssl3_SendApplicationData;
451
452    return SECSuccess;
453}
454