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[CFI] Fix cfi-icall failures

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Control Flow Integrity [1] indirect call checking verifies that function
pointers only call valid functions with a matching type signature.
webrtc casts the function pointers for external_hmac causing a cfi-icall
failure when they are later called in libsrtp. Refactor the functions to
match the correct type signatures to avoid this failure.

[1] https://www.chromium.org/developers/testing/control-flow-integrity

Bug: chromium:776905
Change-Id: I419028be02e6c151c497e3ec64f10f35e07cdb0f
Reviewed-on: https://webrtc-review.googlesource.com/26721
Commit-Queue: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21220}
This commit is contained in:
Vlad Tsyrklevich 2017-12-06 18:38:22 -08:00 committed by Commit Bot
parent 2e27d1cf5e
commit e8e8ad8d19
2 changed files with 23 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
pc/externalhmac.cc
View File

@ -51,10 +51,10 @@ static const char kExternalHmacDescription[] =
static const srtp_auth_type_t external_hmac = {
external_hmac_alloc,
external_hmac_dealloc,
(srtp_auth_init_func) external_hmac_init,
(srtp_auth_compute_func) external_hmac_compute,
(srtp_auth_update_func) external_hmac_update,
(srtp_auth_start_func) external_hmac_start,
external_hmac_init,
external_hmac_compute,
external_hmac_update,
external_hmac_start,
const_cast<char*>(kExternalHmacDescription),
const_cast<srtp_auth_test_case_t*>(&kExternalHmacTestCase0),
EXTERNAL_HMAC_SHA1
@ -104,31 +104,32 @@ srtp_err_status_t external_hmac_dealloc(srtp_auth_t* a) {
return srtp_err_status_ok;
}
srtp_err_status_t external_hmac_init(ExternalHmacContext* state,
srtp_err_status_t external_hmac_init(void* state,
const uint8_t* key,
int key_len) {
if (key_len > HMAC_KEY_LENGTH)
return srtp_err_status_bad_param;
memset(state->key, 0, key_len);
memcpy(state->key, key, key_len);
state->key_length = key_len;
ExternalHmacContext* context = static_cast<ExternalHmacContext*>(state);
memset(context->key, 0, key_len);
memcpy(context->key, key, key_len);
context->key_length = key_len;
return srtp_err_status_ok;
}
srtp_err_status_t external_hmac_start(ExternalHmacContext* state) {
srtp_err_status_t external_hmac_start(void* /*state*/) {
return srtp_err_status_ok;
}
srtp_err_status_t external_hmac_update(ExternalHmacContext* state,
const uint8_t* message,
int msg_octets) {
srtp_err_status_t external_hmac_update(void* /*state*/,
const uint8_t* /*message*/,
int /*msg_octets*/) {
return srtp_err_status_ok;
}
srtp_err_status_t external_hmac_compute(ExternalHmacContext* state,
const void* message,
int msg_octets,
srtp_err_status_t external_hmac_compute(void* /*state*/,
const uint8_t* /*message*/,
int /*msg_octets*/,
int tag_len,
uint8_t* result) {
memcpy(result, kExternalHmacFakeTag, tag_len);

10
pc/externalhmac.h
View File

@ -49,18 +49,18 @@ srtp_err_status_t external_hmac_alloc(srtp_auth_t** a,
srtp_err_status_t external_hmac_dealloc(srtp_auth_t* a);
srtp_err_status_t external_hmac_init(ExternalHmacContext* state,
srtp_err_status_t external_hmac_init(void* state,
const uint8_t* key,
int key_len);
srtp_err_status_t external_hmac_start(ExternalHmacContext* state);
srtp_err_status_t external_hmac_start(void* state);
srtp_err_status_t external_hmac_update(ExternalHmacContext* state,
srtp_err_status_t external_hmac_update(void* state,
const uint8_t* message,
int msg_octets);
srtp_err_status_t external_hmac_compute(ExternalHmacContext* state,
const void* message,
srtp_err_status_t external_hmac_compute(void* state,
const uint8_t* message,
int msg_octets,
int tag_len,
uint8_t* result);