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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is PRIVATE to SSL.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#include "nss.h"
#include "blapit.h"
#include "pk11func.h"
#include "ssl.h"
#include "sslt.h"
#include "sslimpl.h"
#include "selfencrypt.h"
static SECStatus
ssl_MacBuffer(PK11SymKey *key, CK_MECHANISM_TYPE mech,
const unsigned char *in, unsigned int len,
unsigned char *mac, unsigned int *macLen, unsigned int maxMacLen)
{
PK11Context *ctx;
SECItem macParam = { 0, NULL, 0 };
unsigned int computedLen;
SECStatus rv;
ctx = PK11_CreateContextBySymKey(mech, CKA_SIGN, key, &macParam);
if (!ctx) {
PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
return SECFailure;
}
rv = PK11_DigestBegin(ctx);
if (rv != SECSuccess) {
PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
goto loser;
}
rv = PK11_DigestOp(ctx, in, len);
if (rv != SECSuccess) {
PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
goto loser;
}
rv = PK11_DigestFinal(ctx, mac, &computedLen, maxMacLen);
if (rv != SECSuccess) {
PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
goto loser;
}
*macLen = maxMacLen;
PK11_DestroyContext(ctx, PR_TRUE);
return SECSuccess;
loser:
PK11_DestroyContext(ctx, PR_TRUE);
return SECFailure;
}
#ifdef UNSAFE_FUZZER_MODE
SECStatus
ssl_SelfEncryptProtectInt(
PK11SymKey *encKey, PK11SymKey *macKey,
const unsigned char *keyName,
const PRUint8 *in, unsigned int inLen,
PRUint8 *out, unsigned int *outLen, unsigned int maxOutLen)
{
if (inLen > maxOutLen) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
PORT_Memcpy(out, in, inLen);
*outLen = inLen;
return 0;
}
SECStatus
ssl_SelfEncryptUnprotectInt(
PK11SymKey *encKey, PK11SymKey *macKey, const unsigned char *keyName,
const PRUint8 *in, unsigned int inLen,
PRUint8 *out, unsigned int *outLen, unsigned int maxOutLen)
{
if (inLen > maxOutLen) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
PORT_Memcpy(out, in, inLen);
*outLen = inLen;
return 0;
}
#else
/*
* Structure is.
*
* struct {
* opaque keyName[16];
* opaque iv[16];
* opaque ciphertext<16..2^16-1>;
* opaque mac[32];
* } SelfEncrypted;
*
* We are using AES-CBC + HMAC-SHA256 in Encrypt-then-MAC mode for
* two reasons:
*
* 1. It's what we already used for tickets.
* 2. We don't have to worry about nonce collisions as much
* (the chance is lower because we have a random 128-bit nonce
* and they are less serious than with AES-GCM).
*/
SECStatus
ssl_SelfEncryptProtectInt(
PK11SymKey *encKey, PK11SymKey *macKey,
const unsigned char *keyName,
const PRUint8 *in, unsigned int inLen,
PRUint8 *out, unsigned int *outLen, unsigned int maxOutLen)
{
unsigned int len;
unsigned int lenOffset;
unsigned char iv[AES_BLOCK_SIZE];
SECItem ivItem = { siBuffer, iv, sizeof(iv) };
/* Write directly to out. */
sslBuffer buf = SSL_BUFFER_FIXED(out, maxOutLen);
SECStatus rv;
/* Generate a random IV */
rv = PK11_GenerateRandom(iv, sizeof(iv));
if (rv != SECSuccess) {
PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
return SECFailure;
}
/* Add header. */
rv = sslBuffer_Append(&buf, keyName, SELF_ENCRYPT_KEY_NAME_LEN);
if (rv != SECSuccess) {
return SECFailure;
}
rv = sslBuffer_Append(&buf, iv, sizeof(iv));
if (rv != SECSuccess) {
return SECFailure;
}
/* Leave space for the length of the ciphertext. */
rv = sslBuffer_Skip(&buf, 2, &lenOffset);
if (rv != SECSuccess) {
return SECFailure;
}
/* Encode the ciphertext in place. */
rv = PK11_Encrypt(encKey, CKM_AES_CBC_PAD, &ivItem,
SSL_BUFFER_NEXT(&buf), &len,
SSL_BUFFER_SPACE(&buf), in, inLen);
if (rv != SECSuccess) {
return SECFailure;
}
rv = sslBuffer_Skip(&buf, len, NULL);
if (rv != SECSuccess) {
return SECFailure;
}
rv = sslBuffer_InsertLength(&buf, lenOffset, 2);
if (rv != SECSuccess) {
return SECFailure;
}
/* MAC the entire output buffer into the output. */
PORT_Assert(buf.space - buf.len >= SHA256_LENGTH);
rv = ssl_MacBuffer(macKey, CKM_SHA256_HMAC,
SSL_BUFFER_BASE(&buf), /* input */
SSL_BUFFER_LEN(&buf),
SSL_BUFFER_NEXT(&buf), &len, /* output */
SHA256_LENGTH);
if (rv != SECSuccess) {
return SECFailure;
}
rv = sslBuffer_Skip(&buf, len, NULL);
if (rv != SECSuccess) {
return SECFailure;
}
*outLen = SSL_BUFFER_LEN(&buf);
return SECSuccess;
}
SECStatus
ssl_SelfEncryptUnprotectInt(
PK11SymKey *encKey, PK11SymKey *macKey, const unsigned char *keyName,
const PRUint8 *in, unsigned int inLen,
PRUint8 *out, unsigned int *outLen, unsigned int maxOutLen)
{
sslReader reader = SSL_READER(in, inLen);
sslReadBuffer encodedKeyNameBuffer = { 0 };
SECStatus rv = sslRead_Read(&reader, SELF_ENCRYPT_KEY_NAME_LEN,
&encodedKeyNameBuffer);
if (rv != SECSuccess) {
return SECFailure;
}
sslReadBuffer ivBuffer = { 0 };
rv = sslRead_Read(&reader, AES_BLOCK_SIZE, &ivBuffer);
if (rv != SECSuccess) {
return SECFailure;
}
PRUint64 cipherTextLen = 0;
rv = sslRead_ReadNumber(&reader, 2, &cipherTextLen);
if (rv != SECSuccess) {
return SECFailure;
}
sslReadBuffer cipherTextBuffer = { 0 };
rv = sslRead_Read(&reader, (unsigned int)cipherTextLen, &cipherTextBuffer);
if (rv != SECSuccess) {
return SECFailure;
}
unsigned int bytesToMac = reader.offset;
sslReadBuffer encodedMacBuffer = { 0 };
rv = sslRead_Read(&reader, SHA256_LENGTH, &encodedMacBuffer);
if (rv != SECSuccess) {
return SECFailure;
}
/* Make sure we're at the end of the block. */
if (reader.offset != reader.buf.len) {
PORT_SetError(SEC_ERROR_BAD_DATA);
return SECFailure;
}
/* Now that everything is decoded, we can make progress. */
/* 1. Check that we have the right key. */
if (PORT_Memcmp(keyName, encodedKeyNameBuffer.buf, SELF_ENCRYPT_KEY_NAME_LEN)) {
PORT_SetError(SEC_ERROR_NOT_A_RECIPIENT);
return SECFailure;
}
/* 2. Check the MAC */
unsigned char computedMac[SHA256_LENGTH];
unsigned int computedMacLen = 0;
rv = ssl_MacBuffer(macKey, CKM_SHA256_HMAC, in, bytesToMac,
computedMac, &computedMacLen, sizeof(computedMac));
if (rv != SECSuccess) {
return SECFailure;
}
PORT_Assert(computedMacLen == SHA256_LENGTH);
if (NSS_SecureMemcmp(computedMac, encodedMacBuffer.buf, computedMacLen) != 0) {
PORT_SetError(SEC_ERROR_BAD_DATA);
return SECFailure;
}
/* 3. OK, it verifies, now decrypt. */
SECItem ivItem = { siBuffer, (unsigned char *)ivBuffer.buf, AES_BLOCK_SIZE };
rv = PK11_Decrypt(encKey, CKM_AES_CBC_PAD, &ivItem,
out, outLen, maxOutLen, cipherTextBuffer.buf, cipherTextLen);
if (rv != SECSuccess) {
return SECFailure;
}
return SECSuccess;
}
#endif
/* Predict the size of the encrypted data, including padding */
unsigned int
ssl_SelfEncryptGetProtectedSize(unsigned int inLen)
{
return SELF_ENCRYPT_KEY_NAME_LEN +
AES_BLOCK_SIZE +
2 +
((inLen / AES_BLOCK_SIZE) + 1) * AES_BLOCK_SIZE + /* Padded */
SHA256_LENGTH;
}
SECStatus
ssl_SelfEncryptProtect(
sslSocket *ss, const PRUint8 *in, unsigned int inLen,
PRUint8 *out, unsigned int *outLen, unsigned int maxOutLen)
{
PRUint8 keyName[SELF_ENCRYPT_KEY_NAME_LEN];
PK11SymKey *encKey;
PK11SymKey *macKey;
SECStatus rv;
/* Get session ticket keys. */
rv = ssl_GetSelfEncryptKeys(ss, keyName, &encKey, &macKey);
if (rv != SECSuccess) {
SSL_DBG(("%d: SSL[%d]: Unable to get/generate self-encrypt keys.",
SSL_GETPID(), ss->fd));
return SECFailure;
}
return ssl_SelfEncryptProtectInt(encKey, macKey, keyName,
in, inLen, out, outLen, maxOutLen);
}
SECStatus
ssl_SelfEncryptUnprotect(
sslSocket *ss, const PRUint8 *in, unsigned int inLen,
PRUint8 *out, unsigned int *outLen, unsigned int maxOutLen)
{
PRUint8 keyName[SELF_ENCRYPT_KEY_NAME_LEN];
PK11SymKey *encKey;
PK11SymKey *macKey;
SECStatus rv;
/* Get session ticket keys. */
rv = ssl_GetSelfEncryptKeys(ss, keyName, &encKey, &macKey);
if (rv != SECSuccess) {
SSL_DBG(("%d: SSL[%d]: Unable to get/generate self-encrypt keys.",
SSL_GETPID(), ss->fd));
return SECFailure;
}
return ssl_SelfEncryptUnprotectInt(encKey, macKey, keyName,
in, inLen, out, outLen, maxOutLen);
}