Commit 8356fa37 authored by Richard van der Hoff's avatar Richard van der Hoff
Browse files

zero out plaintext buffers

Avoid leaving copies of the plaintext sitting around in the emscripten heap.
parent 76610c0a
......@@ -64,7 +64,7 @@ InboundGroupSession.prototype['create'] = restore_stack(function(session_key) {
InboundGroupSession.prototype['decrypt'] = restore_stack(function(
message
) {
var message_buffer, plaintext_buffer;
var message_buffer, plaintext_buffer, plaintext_length;
try {
message_buffer = malloc(message.length);
......@@ -80,7 +80,7 @@ InboundGroupSession.prototype['decrypt'] = restore_stack(function(
plaintext_buffer = malloc(max_plaintext_length + NULL_BYTE_PADDING_LENGTH);
var message_index = stack(4);
var plaintext_length = inbound_group_session_method(
plaintext_length = inbound_group_session_method(
Module["_olm_group_decrypt"]
)(
this.ptr,
......@@ -105,6 +105,8 @@ InboundGroupSession.prototype['decrypt'] = restore_stack(function(
free(message_buffer);
}
if (plaintext_buffer !== undefined) {
// don't leave a copy of the plaintext in the heap.
bzero(plaintext_buffer, plaintext_length + NULL_BYTE_PADDING_LENGTH);
free(plaintext_buffer);
}
}
......
......@@ -64,9 +64,9 @@ OutboundGroupSession.prototype['create'] = restore_stack(function() {
});
OutboundGroupSession.prototype['encrypt'] = function(plaintext) {
var plaintext_buffer, message_buffer;
var plaintext_buffer, message_buffer, plaintext_length;
try {
var plaintext_length = Module['lengthBytesUTF8'](plaintext);
plaintext_length = Module['lengthBytesUTF8'](plaintext);
var message_length = outbound_group_session_method(
Module['_olm_group_encrypt_message_length']
......@@ -86,6 +86,8 @@ OutboundGroupSession.prototype['encrypt'] = function(plaintext) {
return Module['UTF8ToString'](message_buffer);
} finally {
if (plaintext_buffer !== undefined) {
// don't leave a copy of the plaintext in the heap.
bzero(plaintext_buffer, plaintext_length + 1);
free(plaintext_buffer);
}
if (message_buffer !== undefined) {
......
......@@ -42,6 +42,13 @@ function restore_stack(wrapped) {
}
}
/* set a memory area to zero */
function bzero(ptr, n) {
while(n-- > 0) {
Module['HEAP8'][ptr++] = 0;
}
}
function Account() {
var size = Module['_olm_account_size']();
this.buf = malloc(size);
......@@ -299,7 +306,7 @@ Session.prototype['matches_inbound_from'] = restore_stack(function(
Session.prototype['encrypt'] = restore_stack(function(
plaintext
) {
var plaintext_buffer, message_buffer;
var plaintext_buffer, message_buffer, plaintext_length;
try {
var random_length = session_method(
Module['_olm_encrypt_random_length']
......@@ -308,7 +315,7 @@ Session.prototype['encrypt'] = restore_stack(function(
Module['_olm_encrypt_message_type']
)(this.ptr);
var plaintext_length = Module['lengthBytesUTF8'](plaintext);
plaintext_length = Module['lengthBytesUTF8'](plaintext);
var message_length = session_method(
Module['_olm_encrypt_message_length']
)(this.ptr, plaintext_length);
......@@ -334,6 +341,8 @@ Session.prototype['encrypt'] = restore_stack(function(
};
} finally {
if (plaintext_buffer !== undefined) {
// don't leave a copy of the plaintext in the heap.
bzero(plaintext_buffer, plaintext_length + 1);
free(plaintext_buffer);
}
if (message_buffer !== undefined) {
......@@ -345,13 +354,13 @@ Session.prototype['encrypt'] = restore_stack(function(
Session.prototype['decrypt'] = restore_stack(function(
message_type, message
) {
var message_buffer, plaintext_buffer;
var message_buffer, plaintext_buffer, max_pliantext_length;
try {
message_buffer = malloc(message.length);
Module['writeAsciiToMemory'](message, message_buffer, true);
var max_plaintext_length = session_method(
max_plaintext_length = session_method(
Module['_olm_decrypt_max_plaintext_length']
)(this.ptr, message_type, message_buffer, message.length);
......@@ -379,6 +388,8 @@ Session.prototype['decrypt'] = restore_stack(function(
free(message_buffer);
}
if (plaintext_buffer !== undefined) {
// don't leave a copy of the plaintext in the heap.
bzero(plaintext_buffer, max_plaintext_length + NULL_BYTE_PADDING_LENGTH);
free(plaintext_buffer);
}
}
......
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