1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
|
/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
#include <sys/param.h>
#include <errno.h>
#include <s2n.h>
#include "error/s2n_errno.h"
#include "tls/s2n_cipher_suites.h"
#include "tls/s2n_connection.h"
#include "tls/s2n_handshake.h"
#include "tls/s2n_post_handshake.h"
#include "tls/s2n_record.h"
#include "stuffer/s2n_stuffer.h"
#include "crypto/s2n_cipher.h"
#include "utils/s2n_safety.h"
#include "utils/s2n_blob.h"
int s2n_flush(struct s2n_connection *conn, s2n_blocked_status * blocked)
{
int w;
*blocked = S2N_BLOCKED_ON_WRITE;
/* Write any data that's already pending */
WRITE:
while (s2n_stuffer_data_available(&conn->out)) {
errno = 0;
w = s2n_connection_send_stuffer(&conn->out, conn, s2n_stuffer_data_available(&conn->out));
if (w < 0) {
if (errno == EWOULDBLOCK || errno == EAGAIN) {
S2N_ERROR(S2N_ERR_IO_BLOCKED);
}
S2N_ERROR(S2N_ERR_IO);
}
conn->wire_bytes_out += w;
}
if (conn->closing) {
conn->closed = 1;
}
GUARD(s2n_stuffer_rewrite(&conn->out));
/* If there's an alert pending out, send that */
if (s2n_stuffer_data_available(&conn->reader_alert_out) == 2) {
struct s2n_blob alert = {0};
alert.data = conn->reader_alert_out.blob.data;
alert.size = 2;
GUARD(s2n_record_write(conn, TLS_ALERT, &alert));
GUARD(s2n_stuffer_rewrite(&conn->reader_alert_out));
conn->closing = 1;
/* Actually write it ... */
goto WRITE;
}
/* Do the same for writer driven alerts */
if (s2n_stuffer_data_available(&conn->writer_alert_out) == 2) {
struct s2n_blob alert = {0};
alert.data = conn->writer_alert_out.blob.data;
alert.size = 2;
GUARD(s2n_record_write(conn, TLS_ALERT, &alert));
GUARD(s2n_stuffer_rewrite(&conn->writer_alert_out));
conn->closing = 1;
/* Actually write it ... */
goto WRITE;
}
*blocked = S2N_NOT_BLOCKED;
return 0;
}
ssize_t s2n_sendv_with_offset_impl(struct s2n_connection *conn, const struct iovec *bufs, ssize_t count, ssize_t offs, s2n_blocked_status *blocked)
{
ssize_t user_data_sent, total_size = 0;
S2N_ERROR_IF(conn->closed, S2N_ERR_CLOSED);
S2N_ERROR_IF(conn->config->quic_enabled, S2N_ERR_UNSUPPORTED_WITH_QUIC);
/* Flush any pending I/O */
GUARD(s2n_flush(conn, blocked));
/* Acknowledge consumed and flushed user data as sent */
user_data_sent = conn->current_user_data_consumed;
*blocked = S2N_BLOCKED_ON_WRITE;
uint16_t max_payload_size = 0;
GUARD_AS_POSIX(s2n_record_max_write_payload_size(conn, &max_payload_size));
/* TLS 1.0 and SSLv3 are vulnerable to the so-called Beast attack. Work
* around this by splitting messages into one byte records, and then
* the remainder can follow as usual.
*/
int cbcHackUsed = 0;
struct s2n_crypto_parameters *writer = conn->server;
if (conn->mode == S2N_CLIENT) {
writer = conn->client;
}
/* Defensive check against an invalid retry */
if (offs) {
const struct iovec* _bufs = bufs;
ssize_t _count = count;
while (offs >= _bufs->iov_len && _count > 0) {
offs -= _bufs->iov_len;
_bufs++;
_count--;
}
bufs = _bufs;
count = _count;
}
for (int i = 0; i < count; i++) {
total_size += bufs[i].iov_len;
}
total_size -= offs;
S2N_ERROR_IF(conn->current_user_data_consumed > total_size, S2N_ERR_SEND_SIZE);
if (conn->dynamic_record_timeout_threshold > 0) {
uint64_t elapsed;
GUARD_AS_POSIX(s2n_timer_elapsed(conn->config, &conn->write_timer, &elapsed));
/* Reset record size back to a single segment after threshold seconds of inactivity */
if (elapsed - conn->last_write_elapsed > (uint64_t) conn->dynamic_record_timeout_threshold * 1000000000) {
conn->active_application_bytes_consumed = 0;
}
conn->last_write_elapsed = elapsed;
}
/* Now write the data we were asked to send this round */
while (total_size - conn->current_user_data_consumed) {
ssize_t to_write = MIN(total_size - conn->current_user_data_consumed, max_payload_size);
/* If dynamic record size is enabled,
* use small TLS records that fit into a single TCP segment for the threshold bytes of data
*/
if (conn->active_application_bytes_consumed < (uint64_t) conn->dynamic_record_resize_threshold) {
uint16_t min_payload_size = 0;
GUARD_AS_POSIX(s2n_record_min_write_payload_size(conn, &min_payload_size));
to_write = MIN(min_payload_size, to_write);
}
/* Don't split messages in server mode for interoperability with naive clients.
* Some clients may have expectations based on the amount of content in the first record.
*/
if (conn->actual_protocol_version < S2N_TLS11 && writer->cipher_suite->record_alg->cipher->type == S2N_CBC && conn->mode != S2N_SERVER) {
if (to_write > 1 && cbcHackUsed == 0) {
to_write = 1;
cbcHackUsed = 1;
}
}
GUARD(s2n_stuffer_rewrite(&conn->out));
GUARD(s2n_post_handshake_send(conn, blocked));
/* Write and encrypt the record */
GUARD(s2n_record_writev(conn, TLS_APPLICATION_DATA, bufs, count,
conn->current_user_data_consumed + offs, to_write));
conn->current_user_data_consumed += to_write;
conn->active_application_bytes_consumed += to_write;
/* Send it */
if (s2n_flush(conn, blocked) < 0) {
if (s2n_errno == S2N_ERR_IO_BLOCKED && user_data_sent > 0) {
/* We successfully sent >0 user bytes on the wire, but not the full requested payload
* because we became blocked on I/O. Acknowledge the data sent. */
conn->current_user_data_consumed -= user_data_sent;
return user_data_sent;
} else {
S2N_ERROR_PRESERVE_ERRNO();
}
}
/* Acknowledge consumed and flushed user data as sent */
user_data_sent = conn->current_user_data_consumed;
}
/* If everything has been written, then there's no user data pending */
conn->current_user_data_consumed = 0;
*blocked = S2N_NOT_BLOCKED;
return total_size;
}
ssize_t s2n_sendv_with_offset(struct s2n_connection *conn, const struct iovec *bufs, ssize_t count, ssize_t offs, s2n_blocked_status *blocked)
{
ENSURE_POSIX(!conn->send_in_use, S2N_ERR_REENTRANCY);
conn->send_in_use = true;
ssize_t result = s2n_sendv_with_offset_impl(conn, bufs, count, offs, blocked);
conn->send_in_use = false;
return result;
}
ssize_t s2n_sendv(struct s2n_connection *conn, const struct iovec *bufs, ssize_t count, s2n_blocked_status *blocked)
{
return s2n_sendv_with_offset(conn, bufs, count, 0, blocked);
}
ssize_t s2n_send(struct s2n_connection *conn, const void *buf, ssize_t size, s2n_blocked_status *blocked)
{
struct iovec iov;
iov.iov_base = (void*)(uintptr_t)buf;
iov.iov_len = size;
return s2n_sendv_with_offset(conn, &iov, 1, 0, blocked);
}
|
