Line data Source code
1 : /* fuzz_quic_wire is a simple and stateless fuzz target for fd_quic.
2 :
3 : The attack surface consists of fd_quic's packet handlers.
4 : The input vectors are the raw contents of UDP datagrams (in encrypted
5 : form) A custom mutator is used to temporarily remove the decryption
6 : before calling the generic libFuzzer mutator. If we tried mutating
7 : the encrypted inputs directly, everything would just be an encryption
8 : failure.
9 :
10 : The goal of fuzz_quic_wire is to cover the early upstream stages of
11 : the QUIC packet processing pipeline. This includes packet header
12 : parsing, connection creation, retry handling, etc. */
13 :
14 : #include "../../../util/sanitize/fd_fuzz.h"
15 : #include "fd_quic_test_helpers.h"
16 : #include "../crypto/fd_quic_crypto_suites.h"
17 : #include "../templ/fd_quic_parse_util.h"
18 : #include "../../tls/test_tls_helper.h"
19 : #include "../../../util/net/fd_ip4.h"
20 : #include "../../../util/net/fd_udp.h"
21 : #include "../fd_quic_proto.h"
22 : #include "../fd_quic_proto.c"
23 : #include "../fd_quic_private.h"
24 :
25 : #include <assert.h>
26 : #include <stdlib.h> /* putenv, atexit */
27 :
28 : static FD_TL ulong g_clock;
29 :
30 : static ulong
31 4257 : test_clock( void * context FD_FN_UNUSED ) {
32 4257 : return g_clock;
33 4257 : }
34 :
35 : int
36 : LLVMFuzzerInitialize( int * pargc,
37 15 : char *** pargv ) {
38 15 : putenv( "FD_LOG_BACKTRACE=0" );
39 15 : fd_boot( pargc, pargv );
40 15 : atexit( fd_halt );
41 15 : fd_log_level_logfile_set(0);
42 15 : fd_log_level_stderr_set(0);
43 15 : # ifndef FD_DEBUG_MODE
44 15 : fd_log_level_core_set(3); /* crash on warning log */
45 15 : # endif
46 15 : return 0;
47 15 : }
48 :
49 : static int
50 : _aio_send( void * ctx,
51 : fd_aio_pkt_info_t const * batch,
52 : ulong batch_cnt,
53 : ulong * opt_batch_idx,
54 150 : int flush ) {
55 150 : (void)flush;
56 150 : (void)batch;
57 150 : (void)batch_cnt;
58 150 : (void)opt_batch_idx;
59 150 : (void)ctx;
60 150 : return 0;
61 150 : }
62 :
63 : static void
64 : send_udp_packet( fd_quic_t * quic,
65 : uchar const * data,
66 2088 : ulong size ) {
67 :
68 2088 : uchar buf[16384];
69 :
70 2088 : ulong headers_sz = sizeof(fd_ip4_hdr_t) + sizeof(fd_udp_hdr_t);
71 :
72 2088 : uchar * cur = buf;
73 2088 : uchar * end = buf + sizeof(buf);
74 :
75 2088 : fd_ip4_hdr_t ip4 = {
76 2088 : .verihl = FD_IP4_VERIHL(4,5),
77 2088 : .protocol = FD_IP4_HDR_PROTOCOL_UDP,
78 2088 : .net_tot_len = (ushort)( sizeof(fd_ip4_hdr_t)+sizeof(fd_udp_hdr_t)+size ),
79 2088 : };
80 2088 : fd_udp_hdr_t udp = {
81 2088 : .net_sport = 8000,
82 2088 : .net_dport = 8001,
83 2088 : .net_len = (ushort)( sizeof(fd_udp_hdr_t)+size ),
84 2088 : .check = 0
85 2088 : };
86 :
87 : /* Guaranteed to not overflow */
88 2088 : fd_quic_encode_ip4( cur, (ulong)( end-cur ), &ip4 ); cur += sizeof(fd_ip4_hdr_t);
89 2088 : fd_quic_encode_udp( cur, (ulong)( end-cur ), &udp ); cur += sizeof(fd_udp_hdr_t);
90 :
91 2088 : if( cur + size > end ) return;
92 2088 : fd_memcpy( cur, data, size );
93 :
94 : /* Main fuzz entrypoint */
95 :
96 2088 : fd_quic_process_packet( quic, buf, headers_sz + size );
97 2088 : }
98 :
99 : int
100 : LLVMFuzzerTestOneInput( uchar const * data,
101 2088 : ulong size ) {
102 :
103 2088 : fd_rng_t _rng[1]; fd_rng_t * rng = fd_rng_join( fd_rng_new( _rng, 0U, 0UL ) );
104 :
105 : /* Memory region to hold the QUIC instance */
106 2088 : static uchar quic_mem[ 1<<23 ] __attribute__((aligned(FD_QUIC_ALIGN)));
107 :
108 : /* Create ultra low limits for QUIC instance for maximum performance */
109 2088 : fd_quic_limits_t const quic_limits = {
110 2088 : .conn_cnt = 2,
111 2088 : .handshake_cnt = 2,
112 2088 : .conn_id_cnt = 4,
113 2088 : .inflight_frame_cnt = 16UL,
114 2088 : .stream_pool_cnt = 8UL,
115 2088 : .tx_buf_sz = 1UL<<8UL
116 2088 : };
117 :
118 : /* Enable features depending on the last few bits. The last bits are
119 : pseudorandom (either ignored or belong to the MAC tag) */
120 2088 : uint last_byte = 0U;
121 2088 : if( size > 0 ) last_byte = data[ size-1 ];
122 2088 : int enable_retry = !!(last_byte & 1);
123 2088 : int role = (last_byte & 2) ? FD_QUIC_ROLE_SERVER : FD_QUIC_ROLE_CLIENT;
124 2088 : int established = !!(last_byte & 4);
125 :
126 2088 : assert( fd_quic_footprint( &quic_limits ) <= sizeof(quic_mem) );
127 0 : void * shquic = fd_quic_new( quic_mem, &quic_limits );
128 2088 : fd_quic_t * quic = fd_quic_join( shquic );
129 :
130 2088 : fd_quic_config_anonymous( quic, role );
131 :
132 2088 : fd_tls_test_sign_ctx_t test_signer[1];
133 2088 : fd_tls_test_sign_ctx( test_signer, rng );
134 2088 : fd_quic_config_test_signer( quic, test_signer );
135 :
136 2088 : quic->cb.now = test_clock;
137 2088 : quic->config.retry = enable_retry;
138 :
139 2088 : fd_aio_t aio_[1];
140 2088 : fd_aio_t * aio = fd_aio_join( fd_aio_new( aio_, NULL, _aio_send ) );
141 2088 : assert( aio );
142 :
143 0 : fd_quic_set_aio_net_tx( quic, aio );
144 2088 : assert( fd_quic_init( quic ) );
145 0 : assert( quic->config.idle_timeout > 0 );
146 :
147 0 : fd_quic_state_t * state = fd_quic_get_state( quic );
148 :
149 : /* Create dummy connection */
150 2088 : ulong our_conn_id = ULONG_MAX;
151 2088 : fd_quic_conn_id_t peer_conn_id = { .sz=8 };
152 2088 : uint dst_ip_addr = 0U;
153 2088 : ushort dst_udp_port = (ushort)0;
154 :
155 2088 : fd_quic_conn_t * conn =
156 2088 : fd_quic_conn_create( quic,
157 2088 : our_conn_id, &peer_conn_id,
158 2088 : dst_ip_addr, (ushort)dst_udp_port,
159 2088 : 0U, 0U,
160 2088 : 1 /* we are the server */ );
161 2088 : assert( conn );
162 0 : assert( conn->svc_type == FD_QUIC_SVC_WAIT );
163 :
164 0 : conn->tx_max_data = 512UL;
165 2088 : conn->tx_initial_max_stream_data_uni = 64UL;
166 2088 : conn->srx->rx_max_data = 512UL;
167 2088 : conn->srx->rx_sup_stream_id = 32UL;
168 2088 : conn->tx_max_datagram_sz = FD_QUIC_MTU;
169 2088 : conn->tx_sup_stream_id = 32UL;
170 :
171 2088 : if( established ) {
172 861 : conn->state = FD_QUIC_CONN_STATE_ACTIVE;
173 861 : conn->keys_avail = 0xff;
174 861 : }
175 :
176 2088 : g_clock = 1000UL;
177 :
178 : /* Calls fuzz entrypoint */
179 2088 : send_udp_packet( quic, data, size );
180 :
181 : /* svc_quota is the max number of service calls that we expect to
182 : schedule in response to a single packet. */
183 2088 : long svc_quota = fd_long_max( (long)size, 1000L );
184 :
185 2169 : while( state->svc_queue[ FD_QUIC_SVC_INSTANT ].tail!=UINT_MAX ) {
186 81 : fd_quic_service( quic );
187 81 : assert( --svc_quota > 0 );
188 81 : }
189 2088 : assert( conn->svc_type != FD_QUIC_SVC_INSTANT );
190 :
191 : /* Generate ACKs */
192 2088 : while( state->svc_queue[ FD_QUIC_SVC_ACK_TX ].head != UINT_MAX ) {
193 0 : fd_quic_conn_t * conn = fd_quic_conn_at_idx( state, state->svc_queue[ FD_QUIC_SVC_ACK_TX ].head );
194 0 : g_clock = conn->svc_time;
195 0 : fd_quic_service( quic );
196 0 : assert( --svc_quota > 0 );
197 0 : }
198 2088 : assert( conn->svc_type != FD_QUIC_SVC_INSTANT &&
199 2088 : conn->svc_type != FD_QUIC_SVC_ACK_TX );
200 :
201 : /* Simulate conn timeout */
202 4176 : while( state->svc_queue[ FD_QUIC_SVC_WAIT ].head != UINT_MAX ) {
203 2088 : ulong idle_timeout_ts = conn->last_activity + quic->config.idle_timeout + 1UL;
204 2088 : fd_quic_conn_t * conn = fd_quic_conn_at_idx( state, state->svc_queue[ FD_QUIC_SVC_WAIT ].head );
205 :
206 : /* Idle timeouts should not be scheduled significantly late */
207 2088 : assert( conn->svc_time < idle_timeout_ts + (ulong)2e9 );
208 :
209 0 : g_clock = conn->svc_time;
210 2088 : fd_quic_service( quic );
211 2088 : assert( --svc_quota > 0 );
212 2088 : }
213 2088 : assert( conn->svc_type == UINT_MAX );
214 0 : assert( conn->state == FD_QUIC_CONN_STATE_DEAD || conn->state == FD_QUIC_CONN_STATE_INVALID );
215 :
216 : /* freed stream resources */
217 0 : assert( state->stream_pool->cur_cnt == quic_limits.stream_pool_cnt );
218 0 : assert( conn->used_streams->sentinel );
219 0 : assert( conn->send_streams->sentinel );
220 0 : assert( !conn->tls_hs );
221 :
222 :
223 0 : fd_quic_delete( fd_quic_leave( fd_quic_fini( quic ) ) );
224 2088 : fd_aio_delete( fd_aio_leave( aio ) );
225 2088 : fd_rng_delete( fd_rng_leave( rng ) );
226 2088 : return 0;
227 2088 : }
228 :
229 : #if !FD_QUIC_DISABLE_CRYPTO
230 :
231 : static fd_quic_crypto_keys_t const keys[1] = {{
232 : .pkt_key = {0},
233 : .iv = {0},
234 : .hp_key = {0},
235 : }};
236 :
237 : /* guess_packet_size attempts to discover the end of a QUIC packet.
238 : Returns the total length (including GCM tag) on success, sets *pn_off
239 : to the packet number offset and *pn to the packet number. Returns
240 : 0UL on failure. */
241 :
242 : static ulong
243 : guess_packet_size( uchar const * data,
244 : ulong size,
245 0 : ulong * pn_off ) {
246 :
247 0 : uchar const * cur_ptr = data;
248 0 : ulong cur_sz = size;
249 :
250 0 : ulong pkt_num_pnoff = 0UL;
251 0 : ulong total_len = size;
252 :
253 0 : if( FD_UNLIKELY( size < 1 ) ) return FD_QUIC_PARSE_FAIL;
254 0 : uchar hdr_form = fd_quic_h0_hdr_form( *cur_ptr );
255 :
256 0 : ulong rc;
257 0 : if( hdr_form == 1 ) { /* long header */
258 :
259 0 : uchar long_packet_type = fd_quic_h0_long_packet_type( *cur_ptr );
260 0 : cur_ptr += 1; cur_sz -= 1UL;
261 0 : fd_quic_long_hdr_t long_hdr[1];
262 0 : rc = fd_quic_decode_long_hdr( long_hdr, cur_ptr, cur_sz );
263 0 : if( rc == FD_QUIC_PARSE_FAIL ) return 0UL;
264 0 : cur_ptr += rc; cur_sz -= rc;
265 :
266 0 : switch( long_packet_type ) {
267 0 : case FD_QUIC_PKT_TYPE_INITIAL: {
268 0 : fd_quic_initial_t initial[1];
269 0 : rc = fd_quic_decode_initial( initial, cur_ptr, cur_sz );
270 0 : if( rc == FD_QUIC_PARSE_FAIL ) return 0UL;
271 0 : cur_ptr += rc; cur_sz -= rc;
272 :
273 0 : pkt_num_pnoff = initial->pkt_num_pnoff;
274 0 : total_len = pkt_num_pnoff + initial->len;
275 0 : break;
276 0 : }
277 0 : case FD_QUIC_PKT_TYPE_HANDSHAKE: {
278 0 : fd_quic_handshake_t handshake[1];
279 0 : rc = fd_quic_decode_handshake( handshake, cur_ptr, cur_sz );
280 0 : if( rc == FD_QUIC_PARSE_FAIL ) return 0UL;
281 0 : cur_ptr += rc; cur_sz -= rc;
282 :
283 0 : pkt_num_pnoff = handshake->pkt_num_pnoff;
284 0 : total_len = pkt_num_pnoff + handshake->len;
285 0 : break;
286 0 : }
287 0 : case FD_QUIC_PKT_TYPE_RETRY:
288 : /* Do we need to decrypt Retry packets? I'm not sure */
289 : /* TODO correctly derive size of packet in case there is another
290 : packet following the retry packet */
291 0 : return 0UL;
292 0 : case FD_QUIC_PKT_TYPE_ZERO_RTT:
293 : /* No support for 0-RTT yet */
294 0 : return 0UL;
295 0 : default:
296 0 : __builtin_unreachable();
297 0 : }
298 :
299 0 : } else { /* short header */
300 :
301 0 : fd_quic_one_rtt_t one_rtt[1];
302 0 : one_rtt->dst_conn_id_len = 8;
303 0 : rc = fd_quic_decode_one_rtt( one_rtt, cur_ptr, cur_sz );
304 0 : if( rc == FD_QUIC_PARSE_FAIL ) return 0UL;
305 0 : cur_ptr += rc; cur_sz -= rc;
306 :
307 0 : pkt_num_pnoff = one_rtt->pkt_num_pnoff;
308 :
309 0 : }
310 :
311 0 : *pn_off = pkt_num_pnoff;
312 0 : return total_len;
313 0 : }
314 :
315 : /* decrypt_packet attempts to decrypt the first QUIC packet in the given
316 : buffer. data points to the first byte of the QUIC packet. size is
317 : the number of bytes until the end of the UDP datagram. Returns the
318 : number of bytes that belonged to the first packet (<= size) on
319 : success. Returns 0 on failure and leaves the packet (partially)
320 : encrypted. */
321 :
322 : static ulong
323 : decrypt_packet( uchar * const data,
324 0 : ulong const size ) {
325 :
326 0 : ulong pkt_num_pnoff = 0UL;
327 0 : ulong total_len = guess_packet_size( data, size, &pkt_num_pnoff );
328 0 : if( !total_len ) return 0UL;
329 :
330 : /* Decrypt the packet */
331 :
332 0 : int decrypt_res = fd_quic_crypto_decrypt_hdr( data, size, pkt_num_pnoff, keys );
333 0 : if( decrypt_res != FD_QUIC_SUCCESS ) return 0UL;
334 :
335 0 : uint pkt_number_sz = fd_quic_h0_pkt_num_len( data[0] ) + 1u;
336 0 : ulong pkt_number = fd_quic_pktnum_decode( data+pkt_num_pnoff, pkt_number_sz );
337 :
338 0 : decrypt_res =
339 0 : fd_quic_crypto_decrypt( data, size,
340 0 : pkt_num_pnoff, pkt_number,
341 0 : keys );
342 0 : if( decrypt_res != FD_QUIC_SUCCESS ) return 0UL;
343 :
344 0 : return fd_ulong_min( total_len + FD_QUIC_CRYPTO_TAG_SZ, size );
345 0 : }
346 :
347 : /* decrypt_payload attempts to remove packet protection of a UDP
348 : datagram payload in-place. Note that a UDP datagram can contain
349 : multiple QUIC packets. */
350 :
351 : static int
352 : decrypt_payload( uchar * data,
353 0 : ulong size ) {
354 :
355 0 : if( size < 16 ) return 0;
356 :
357 : /* Heuristic: If the last 16 bytes of the packet (the AES-GCM tag) are
358 : zero consider it an unencrypted packet */
359 :
360 0 : uint mask=0U;
361 0 : for( ulong j=0UL; j<16UL; j++ ) mask |= data[size-16+j];
362 0 : if( !mask ) return 1;
363 :
364 0 : uchar * cur_ptr = data;
365 0 : ulong cur_sz = size;
366 :
367 0 : do {
368 :
369 0 : ulong sz = decrypt_packet( cur_ptr, cur_sz );
370 0 : if( !sz ) return 0;
371 0 : assert( sz <= cur_sz ); /* prevent out of bounds */
372 :
373 0 : cur_ptr += sz; cur_sz -= sz;
374 :
375 0 : } while( cur_sz );
376 :
377 0 : return 1;
378 0 : }
379 :
380 : static ulong
381 : encrypt_packet( uchar * const data,
382 0 : ulong const size ) {
383 :
384 0 : uchar out[ FD_QUIC_MTU ];
385 :
386 0 : ulong pkt_num_pnoff = 0UL;
387 0 : ulong total_len = guess_packet_size( data, size, &pkt_num_pnoff );
388 0 : if( ( total_len < FD_QUIC_CRYPTO_TAG_SZ ) |
389 0 : ( total_len > size ) |
390 0 : ( total_len > sizeof(out) ) )
391 0 : return size;
392 :
393 0 : uchar first = data[0];
394 0 : ulong pkt_number_sz = ( first & 0x03u ) + 1;
395 :
396 0 : ulong out_sz = total_len;
397 0 : uchar const * hdr = data;
398 0 : ulong hdr_sz = pkt_num_pnoff + pkt_number_sz;
399 :
400 0 : ulong pkt_number = 0UL;
401 0 : for( ulong j = 0UL; j < pkt_number_sz; ++j ) {
402 0 : pkt_number = ( pkt_number << 8UL ) + (ulong)( hdr[pkt_num_pnoff + j] );
403 0 : }
404 :
405 0 : if( ( out_sz < hdr_sz ) |
406 0 : ( out_sz - hdr_sz < FD_QUIC_CRYPTO_TAG_SZ ) )
407 0 : return size;
408 :
409 0 : uchar const * pay = hdr + hdr_sz;
410 0 : ulong pay_sz = out_sz - hdr_sz - FD_QUIC_CRYPTO_TAG_SZ;
411 :
412 0 : int encrypt_res =
413 0 : fd_quic_crypto_encrypt( out, &out_sz,
414 0 : hdr, hdr_sz,
415 0 : pay, pay_sz,
416 0 : keys, keys,
417 0 : pkt_number );
418 0 : if( encrypt_res != FD_QUIC_SUCCESS )
419 0 : return size;
420 0 : assert( out_sz == total_len );
421 :
422 0 : fd_memcpy( data, out, out_sz );
423 0 : return out_sz;
424 0 : }
425 :
426 : static void
427 : encrypt_payload( uchar * data,
428 0 : ulong size ) {
429 :
430 0 : uchar * cur_ptr = data;
431 0 : ulong cur_sz = size;
432 :
433 0 : while( cur_sz ) {
434 0 : ulong sz = encrypt_packet( cur_ptr, cur_sz );
435 0 : assert( sz ); /* prevent infinite loop */
436 0 : assert( sz <= cur_sz ); /* prevent out of bounds */
437 :
438 0 : cur_ptr += sz; cur_sz -= sz;
439 0 : }
440 0 : }
441 :
442 : /* LLVMFuzzerCustomMutator has the following behavior:
443 :
444 : - If the input is not encrypted, mutates the raw input, and produces
445 : an encrypted output
446 : - If the input is encrypted, mutates the decrypted input, and
447 : produces another encrypted output
448 : - If the input appears to be encrypted but fails to decrypt, mutates
449 : the raw encrypted input, and produces another output that will fail
450 : to decrypt. */
451 :
452 : ulong
453 : LLVMFuzzerCustomMutator( uchar * data,
454 : ulong data_sz,
455 : ulong max_sz,
456 0 : uint seed ) {
457 0 : int ok = decrypt_payload( data, data_sz );
458 0 : data_sz = LLVMFuzzerMutate( data, data_sz, max_sz );
459 0 : if( ok ) encrypt_payload( data, data_sz );
460 0 : (void)seed;
461 0 : return data_sz;
462 0 : }
463 :
464 : /* Find a strategy for custom crossover of decrypted packets */
465 :
466 : #endif /* !FD_QUIC_DISABLE_CRYPTO */
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