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Allow always max 1024 padding for HEADERS 

We need paddings regardless of payload and frame boundary to mitigate
certain attacks.

Since we handles CONTINUATION internally, we don't show FLAG_PAD_HIGH
and PAD_LOW flags of HEADERS in nghttp/nghttpd. We just show the
total paddings in HEADERS + CONTINUATION.
This commit is contained in:
Tatsuhiro Tsujikawa 2014-02-15 01:34:04 +09:00
parent 622f783675
commit 1e95c8b313
4 changed files with 109 additions and 15 deletions
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71
lib/nghttp2_session.c
View File

@ -1141,10 +1141,7 @@ static ssize_t nghttp2_session_prep_frame(nghttp2_session *session,
return framebuflen;
}
padded_payloadlen = session_call_select_padding
(session, frame,
(frame->hd.length == 0 ? NGHTTP2_MAX_FRAME_LENGTH :
(frame->hd.length + NGHTTP2_MAX_FRAME_LENGTH - 1)
/ NGHTTP2_MAX_FRAME_LENGTH * NGHTTP2_MAX_FRAME_LENGTH));
(session, frame, frame->hd.length + 1024);
if(nghttp2_is_fatal(padded_payloadlen)) {
return padded_payloadlen;
}
@ -1152,13 +1149,46 @@ static ssize_t nghttp2_session_prep_frame(nghttp2_session *session,
frame->headers.padlen = padded_payloadlen - frame->hd.length;
frame->hd.length = padded_payloadlen;
DEBUGF(fprintf(stderr, "payloadlen=%zu, padlen=%zu\n",
frame->hd.length, frame->headers.padlen));
if(frame->hd.length > NGHTTP2_MAX_FRAME_LENGTH) {
/* PAD_HIGH and PAD_LOW will be added in
nghttp2_session_after_frame_sent(). */
/* This may make framebuflen > session->aob.framebufmax. But
if(NGHTTP2_MAX_FRAME_LENGTH >
frame->hd.length - frame->headers.padlen) {
size_t padlen = NGHTTP2_MAX_FRAME_LENGTH -
(frame->hd.length - frame->headers.padlen);
nghttp2_frame_hd hd = frame->hd;
DEBUGF(fprintf(stderr, "padding across 2 frames\n"));
hd.flags &= ~NGHTTP2_FLAG_END_HEADERS;
hd.length = NGHTTP2_MAX_FRAME_LENGTH;
DEBUGF(fprintf(stderr, "first HEADERS payloadlen=%zu, padlen=%zu\n",
hd.length, padlen));
r = nghttp2_frame_add_pad(&session->aob.framebuf,
&session->aob.framebufmax,
&session->aob.framebufoff,
&hd.flags,
hd.length - padlen,
padlen);
if(nghttp2_is_fatal(r)) {
return r;
}
framebuflen = session->aob.framebufoff + frame->hd.length
+ NGHTTP2_FRAME_HEAD_LENGTH;
nghttp2_frame_pack_frame_hd
(session->aob.framebuf + session->aob.framebufoff, &hd);
} else {
/* PAD_HIGH and PAD_LOW will be added in
nghttp2_session_after_frame_sent(). */
framebuflen += frame->headers.padlen;
}
/* At this point, framebuflen > session->aob.framebufmax. But
before we access the missing part, we will allocate it in
nghttp2_session_after_frame_sent(). */
framebuflen += frame->headers.padlen;
} else if(frame->hd.length <= NGHTTP2_MAX_FRAME_LENGTH &&
frame->headers.padlen > 0) {
r = nghttp2_frame_add_pad(&session->aob.framebuf,
@ -1504,17 +1534,24 @@ static int nghttp2_session_after_frame_sent(nghttp2_session *session)
session->aob.framebufoff -= NGHTTP2_FRAME_HEAD_LENGTH;
if(cont_hd.length + session->aob.framebufmark ==
session->aob.framebuflen) {
size_t padlen;
if(cont_hd.length < frame->headers.padlen) {
padlen = cont_hd.length;
} else {
padlen = frame->headers.padlen;
}
DEBUGF(fprintf(stderr,
"last CONTINUATION payloadlen=%zu, padlen=%zu\n",
cont_hd.length, frame->headers.padlen));
cont_hd.length, padlen));
cont_hd.flags = NGHTTP2_FLAG_END_HEADERS;
rv = nghttp2_frame_add_pad(&session->aob.framebuf,
&session->aob.framebufmax,
&session->aob.framebufoff,
&cont_hd.flags,
cont_hd.length - frame->headers.padlen,
frame->headers.padlen);
cont_hd.length - padlen,
padlen);
if(nghttp2_is_fatal(rv)) {
return rv;
}
@ -1524,9 +1561,6 @@ static int nghttp2_session_after_frame_sent(nghttp2_session *session)
session->aob.framebuflen = session->aob.framebufmark =
session->aob.framebufoff + NGHTTP2_FRAME_HEAD_LENGTH +
cont_hd.length;
/* Or-ing flags so that we can show these flags in
callback */
frame->hd.flags |= cont_hd.flags;
} else {
cont_hd.flags = NGHTTP2_FLAG_NONE;
session->aob.framebufmark += cont_hd.length;
@ -3506,6 +3540,8 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
nghttp2_frame_unpack_frame_hd(&iframe->frame.hd, iframe->buf);
iframe->payloadleft = iframe->frame.hd.length;
DEBUGF(fprintf(stderr, "payloadlen=%zu\n", iframe->payloadleft));
switch(iframe->frame.hd.type) {
case NGHTTP2_DATA: {
DEBUGF(fprintf(stderr, "DATA\n"));
@ -3841,6 +3877,10 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
if(iframe->payloadleft) {
break;
}
/* Clear PAD_HIGH and PAD_LOW, because we rely on those flags
in the next CONTINUATION frame. */
iframe->frame.hd.flags &=
~(NGHTTP2_FLAG_PAD_HIGH | NGHTTP2_FLAG_PAD_LOW);
if((iframe->frame.hd.flags & NGHTTP2_FLAG_END_HEADERS) == 0) {
inbound_frame_reset_left(iframe, NGHTTP2_FRAME_HEAD_LENGTH);
iframe->padlen = 0;
@ -3950,6 +3990,9 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
}
nghttp2_frame_unpack_frame_hd(&cont_hd, iframe->buf);
iframe->payloadleft = cont_hd.length;
DEBUGF(fprintf(stderr, "payloadlen=%zu\n", iframe->payloadleft));
if(cont_hd.type != NGHTTP2_CONTINUATION ||
cont_hd.stream_id != iframe->frame.hd.stream_id) {
DEBUGF(fprintf(stderr, "expected stream_id=%d, type=%d, but "

2
tests/main.c
View File

@ -199,6 +199,8 @@ int main(int argc, char* argv[])
test_nghttp2_session_data_backoff_by_high_pri_frame) ||
!CU_add_test(pSuite, "session_pack_data_with_padding",
test_nghttp2_session_pack_data_with_padding) ||
!CU_add_test(pSuite, "session_pack_headers_with_padding",
test_nghttp2_session_pack_headers_with_padding) ||
!CU_add_test(pSuite, "pack_settings_payload",
test_nghttp2_pack_settings_payload) ||
!CU_add_test(pSuite, "frame_pack_headers",

50
tests/nghttp2_session_test.c
View File

@ -40,7 +40,7 @@
#define OB_DATA(ITEM) nghttp2_outbound_item_get_data_frame(ITEM)
typedef struct {
uint8_t buf[4096];
uint8_t buf[65535];
size_t length;
} accumulator;
@ -4039,6 +4039,54 @@ void test_nghttp2_session_pack_data_with_padding(void)
nghttp2_session_del(session);
}
void test_nghttp2_session_pack_headers_with_padding(void)
{
nghttp2_session *session, *sv_session;
accumulator acc;
my_user_data ud;
nghttp2_session_callbacks callbacks, sv_callbacks;
nghttp2_nv nva[8190];
size_t i;
for(i = 0; i < ARRLEN(nva); ++i) {
nva[i].name = (uint8_t*)":path";
nva[i].namelen = 5;
nva[i].value = (uint8_t*)"/";
nva[i].valuelen = 1;
}
memset(&callbacks, 0, sizeof(callbacks));
callbacks.send_callback = accumulator_send_callback;
callbacks.on_frame_send_callback = on_frame_send_callback;
callbacks.select_padding_callback = select_padding_callback;
acc.length = 0;
ud.acc = &acc;
memset(&sv_callbacks, 0, sizeof(sv_callbacks));
sv_callbacks.on_frame_recv_callback = on_frame_recv_callback;
nghttp2_session_client_new(&session, &callbacks, &ud);
nghttp2_session_server_new(&sv_session, &sv_callbacks, &ud);
ud.padding_boundary = 16385;
CU_ASSERT(0 ==
nghttp2_submit_request(session, NGHTTP2_PRI_DEFAULT,
nva, ARRLEN(nva), NULL, NULL));
CU_ASSERT(0 == nghttp2_session_send(session));
CU_ASSERT(acc.length > NGHTTP2_MAX_FRAME_LENGTH);
ud.frame_recv_cb_called = 0;
CU_ASSERT((ssize_t)acc.length ==
nghttp2_session_mem_recv(sv_session, acc.buf, acc.length));
CU_ASSERT(1 == ud.frame_recv_cb_called);
CU_ASSERT(NULL == nghttp2_session_get_next_ob_item(sv_session));
nghttp2_session_del(sv_session);
nghttp2_session_del(session);
}
void test_nghttp2_pack_settings_payload(void)
{
nghttp2_settings_entry iv[2];

1
tests/nghttp2_session_test.h
View File

@ -90,6 +90,7 @@ void test_nghttp2_session_get_effective_local_window_size(void);
void test_nghttp2_session_set_option(void);
void test_nghttp2_session_data_backoff_by_high_pri_frame(void);
void test_nghttp2_session_pack_data_with_padding(void);
void test_nghttp2_session_pack_headers_with_padding(void);
void test_nghttp2_pack_settings_payload(void);
#endif /* NGHTTP2_SESSION_TEST_H */