mozilla-central/security/nss/lib/ssl/tls13ech.c (file symbol)

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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* 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
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "nss.h"
#include "pk11func.h"
#include "pk11hpke.h"
#include "ssl.h"
#include "sslproto.h"
#include "sslimpl.h"
#include "selfencrypt.h"
#include "ssl3exthandle.h"
#include "tls13ech.h"
#include "tls13exthandle.h"
#include "tls13hashstate.h"
#include "tls13hkdf.h"
extern SECStatus
ssl3_UpdateHandshakeHashesInt(sslSocket *ss, const unsigned char *b,
unsigned int l, sslBuffer *transcriptBuf);
extern SECStatus
ssl3_HandleClientHelloPreamble(sslSocket *ss, PRUint8 **b, PRUint32 *length, SECItem *sidBytes,
SECItem *cookieBytes, SECItem *suites, SECItem *comps);
extern SECStatus
tls13_DeriveSecret(sslSocket *ss, PK11SymKey *key,
const char *label,
unsigned int labelLen,
const SSL3Hashes *hashes,
PK11SymKey **dest,
SSLHashType hash);
PRBool
tls13_Debug_CheckXtnBegins(const PRUint8 *start, const PRUint16 xtnType)
{
#ifdef DEBUG
SECStatus rv;
sslReader ext_reader = SSL_READER(start, 2);
PRUint64 extension_number;
rv = sslRead_ReadNumber(&ext_reader, 2, &extension_number);
return ((rv == SECSuccess) && (extension_number == xtnType));
#else
return PR_TRUE;
#endif
}
void
tls13_DestroyEchConfig(sslEchConfig *config)
{
if (!config) {
return;
}
SECITEM_FreeItem(&config->contents.publicKey, PR_FALSE);
SECITEM_FreeItem(&config->contents.suites, PR_FALSE);
SECITEM_FreeItem(&config->raw, PR_FALSE);
PORT_Free(config->contents.publicName);
config->contents.publicName = NULL;
PORT_ZFree(config, sizeof(*config));
}
void
tls13_DestroyEchConfigs(PRCList *list)
{
PRCList *cur_p;
while (!PR_CLIST_IS_EMPTY(list)) {
cur_p = PR_LIST_TAIL(list);
PR_REMOVE_LINK(cur_p);
tls13_DestroyEchConfig((sslEchConfig *)cur_p);
}
}
void
tls13_DestroyEchXtnState(sslEchXtnState *state)
{
if (!state) {
return;
}
SECITEM_FreeItem(&state->innerCh, PR_FALSE);
SECITEM_FreeItem(&state->senderPubKey, PR_FALSE);
SECITEM_FreeItem(&state->retryConfigs, PR_FALSE);
PORT_ZFree(state, sizeof(*state));
}
SECStatus
tls13_CopyEchConfigs(PRCList *oConfigs, PRCList *configs)
{
SECStatus rv;
sslEchConfig *config;
sslEchConfig *newConfig = NULL;
for (PRCList *cur_p = PR_LIST_HEAD(oConfigs);
cur_p != oConfigs;
cur_p = PR_NEXT_LINK(cur_p)) {
config = (sslEchConfig *)PR_LIST_TAIL(oConfigs);
newConfig = PORT_ZNew(sslEchConfig);
if (!newConfig) {
goto loser;
}
rv = SECITEM_CopyItem(NULL, &newConfig->raw, &config->raw);
if (rv != SECSuccess) {
goto loser;
}
newConfig->contents.publicName = PORT_Strdup(config->contents.publicName);
if (!newConfig->contents.publicName) {
goto loser;
}
rv = SECITEM_CopyItem(NULL, &newConfig->contents.publicKey,
&config->contents.publicKey);
if (rv != SECSuccess) {
goto loser;
}
rv = SECITEM_CopyItem(NULL, &newConfig->contents.suites,
&config->contents.suites);
if (rv != SECSuccess) {
goto loser;
}
newConfig->contents.configId = config->contents.configId;
newConfig->contents.kemId = config->contents.kemId;
newConfig->contents.kdfId = config->contents.kdfId;
newConfig->contents.aeadId = config->contents.aeadId;
newConfig->contents.maxNameLen = config->contents.maxNameLen;
newConfig->version = config->version;
PR_APPEND_LINK(&newConfig->link, configs);
}
return SECSuccess;
loser:
tls13_DestroyEchConfig(newConfig);
tls13_DestroyEchConfigs(configs);
return SECFailure;
}
/*
* struct {
* HpkeKdfId kdf_id;
* HpkeAeadId aead_id;
* } HpkeSymmetricCipherSuite;
*
* struct {
* uint8 config_id;
* HpkeKemId kem_id;
* HpkePublicKey public_key;
* HpkeSymmetricCipherSuite cipher_suites<4..2^16-4>;
* } HpkeKeyConfig;
*
* struct {
* HpkeKeyConfig key_config;
* uint16 maximum_name_length;
* opaque public_name<1..2^16-1>;
* Extension extensions<0..2^16-1>;
* } ECHConfigContents;
*
* struct {
* uint16 version;
* uint16 length;
* select (ECHConfig.version) {
* case 0xfe0d: ECHConfigContents contents;
* }
* } ECHConfig;
*/
static SECStatus
tls13_DecodeEchConfigContents(const sslReadBuffer *rawConfig,
sslEchConfig **outConfig)
{
SECStatus rv;
sslEchConfigContents contents = { 0 };
sslEchConfig *decodedConfig;
PRUint64 tmpn;
PRUint64 tmpn2;
sslReadBuffer tmpBuf;
PRUint16 *extensionTypes = NULL;
unsigned int extensionIndex = 0;
sslReader configReader = SSL_READER(rawConfig->buf, rawConfig->len);
sslReader suiteReader;
sslReader extensionReader;
PRBool hasValidSuite = PR_FALSE;
PRBool unsupportedMandatoryXtn = PR_FALSE;
/* HpkeKeyConfig key_config */
/* uint8 config_id */
rv = sslRead_ReadNumber(&configReader, 1, &tmpn);
if (rv != SECSuccess) {
goto loser;
}
contents.configId = tmpn;
/* HpkeKemId kem_id */
rv = sslRead_ReadNumber(&configReader, 2, &tmpn);
if (rv != SECSuccess) {
goto loser;
}
contents.kemId = tmpn;
/* HpkePublicKey public_key */
rv = sslRead_ReadVariable(&configReader, 2, &tmpBuf);
if (rv != SECSuccess) {
goto loser;
}
rv = SECITEM_MakeItem(NULL, &contents.publicKey, (PRUint8 *)tmpBuf.buf, tmpBuf.len);
if (rv != SECSuccess) {
goto loser;
}
/* HpkeSymmetricCipherSuite cipher_suites<4..2^16-4> */
rv = sslRead_ReadVariable(&configReader, 2, &tmpBuf);
if (rv != SECSuccess) {
goto loser;
}
if (tmpBuf.len & 1) {
PORT_SetError(SSL_ERROR_RX_MALFORMED_ECH_CONFIG);
goto loser;
}
suiteReader = (sslReader)SSL_READER(tmpBuf.buf, tmpBuf.len);
while (SSL_READER_REMAINING(&suiteReader)) {
/* HpkeKdfId kdf_id */
rv = sslRead_ReadNumber(&suiteReader, 2, &tmpn);
if (rv != SECSuccess) {
goto loser;
}
/* HpkeAeadId aead_id */
rv = sslRead_ReadNumber(&suiteReader, 2, &tmpn2);
if (rv != SECSuccess) {
goto loser;
}
if (!hasValidSuite) {
/* Use the first compatible ciphersuite. */
rv = PK11_HPKE_ValidateParameters(contents.kemId, tmpn, tmpn2);
if (rv == SECSuccess) {
hasValidSuite = PR_TRUE;
contents.kdfId = tmpn;
contents.aeadId = tmpn2;
break;
}
}
}
rv = SECITEM_MakeItem(NULL, &contents.suites, (PRUint8 *)tmpBuf.buf, tmpBuf.len);
if (rv != SECSuccess) {
goto loser;
}
/* uint8 maximum_name_length */
rv = sslRead_ReadNumber(&configReader, 1, &tmpn);
if (rv != SECSuccess) {
goto loser;
}
contents.maxNameLen = (PRUint8)tmpn;
/* opaque public_name<1..2^16-1> */
rv = sslRead_ReadVariable(&configReader, 1, &tmpBuf);
if (rv != SECSuccess) {
goto loser;
}
if (tmpBuf.len == 0) {
PORT_SetError(SSL_ERROR_RX_MALFORMED_ECH_CONFIG);
goto loser;
}
if (!tls13_IsLDH(tmpBuf.buf, tmpBuf.len) ||
tls13_IsIp(tmpBuf.buf, tmpBuf.len)) {
PORT_SetError(SSL_ERROR_RX_MALFORMED_ECH_CONFIG);
goto loser;
}
contents.publicName = PORT_ZAlloc(tmpBuf.len + 1);
if (!contents.publicName) {
goto loser;
}
PORT_Memcpy(contents.publicName, (PRUint8 *)tmpBuf.buf, tmpBuf.len);
/* Extensions. We don't support any, but must
* check for any that are marked critical. */
rv = sslRead_ReadVariable(&configReader, 2, &tmpBuf);
if (rv != SECSuccess) {
goto loser;
}
extensionReader = (sslReader)SSL_READER(tmpBuf.buf, tmpBuf.len);
extensionTypes = PORT_NewArray(PRUint16, tmpBuf.len / 2 * sizeof(PRUint16));
if (!extensionTypes) {
goto loser;
}
while (SSL_READER_REMAINING(&extensionReader)) {
/* Get the extension's type field */
rv = sslRead_ReadNumber(&extensionReader, 2, &tmpn);
if (rv != SECSuccess) {
goto loser;
}
for (unsigned int i = 0; i < extensionIndex; i++) {
if (extensionTypes[i] == tmpn) {
PORT_SetError(SEC_ERROR_EXTENSION_VALUE_INVALID);
goto loser;
}
}
extensionTypes[extensionIndex++] = (PRUint16)tmpn;
/* Clients MUST parse the extension list and check for unsupported
* mandatory extensions. If an unsupported mandatory extension is
* present, clients MUST ignore the ECHConfig
* [draft-ietf-tls-esni, Section 4.2]. */
if (tmpn & (1 << 15)) {
unsupportedMandatoryXtn = PR_TRUE;
}
/* Skip. */
rv = sslRead_ReadVariable(&extensionReader, 2, &tmpBuf);
if (rv != SECSuccess) {
goto loser;
}
}
/* Check that we consumed the entire ECHConfig */
if (SSL_READER_REMAINING(&configReader)) {
PORT_SetError(SSL_ERROR_RX_MALFORMED_ECH_CONFIG);
goto loser;
}
/* If the ciphersuites were compatible AND if NO unsupported mandatory
* extensions were found set the outparam. Return success either way if the
* config was well-formed. */
if (hasValidSuite && !unsupportedMandatoryXtn) {
decodedConfig = PORT_ZNew(sslEchConfig);
if (!decodedConfig) {
goto loser;
}
decodedConfig->contents = contents;
*outConfig = decodedConfig;
} else {
PORT_Free(contents.publicName);
SECITEM_FreeItem(&contents.publicKey, PR_FALSE);
SECITEM_FreeItem(&contents.suites, PR_FALSE);
}
PORT_Free(extensionTypes);
return SECSuccess;
loser:
PORT_Free(extensionTypes);
PORT_Free(contents.publicName);
SECITEM_FreeItem(&contents.publicKey, PR_FALSE);
SECITEM_FreeItem(&contents.suites, PR_FALSE);
return SECFailure;
}
/* Decode an ECHConfigList struct and store each ECHConfig
* into |configs|. */
SECStatus
tls13_DecodeEchConfigs(const SECItem *data, PRCList *configs)
{
SECStatus rv;
sslEchConfig *decodedConfig = NULL;
sslReader rdr = SSL_READER(data->data, data->len);
sslReadBuffer tmp;
sslReadBuffer singleConfig;
PRUint64 version;
PRUint64 length;
PORT_Assert(PR_CLIST_IS_EMPTY(configs));
rv = sslRead_ReadVariable(&rdr, 2, &tmp);
if (rv != SECSuccess) {
return SECFailure;
}
SSL_TRC(100, ("Read EchConfig list of size %u", SSL_READER_REMAINING(&rdr)));
if (SSL_READER_REMAINING(&rdr)) {
PORT_SetError(SEC_ERROR_BAD_DATA);
return SECFailure;
}
sslReader configsReader = SSL_READER(tmp.buf, tmp.len);
if (!SSL_READER_REMAINING(&configsReader)) {
PORT_SetError(SEC_ERROR_BAD_DATA);
return SECFailure;
}
/* Handle each ECHConfig. */
while (SSL_READER_REMAINING(&configsReader)) {
singleConfig.buf = SSL_READER_CURRENT(&configsReader);
/* uint16 version */
rv = sslRead_ReadNumber(&configsReader, 2, &version);
if (rv != SECSuccess) {
goto loser;
}
/* uint16 length */
rv = sslRead_ReadNumber(&configsReader, 2, &length);
if (rv != SECSuccess) {
goto loser;
}
singleConfig.len = 4 + length;
rv = sslRead_Read(&configsReader, length, &tmp);
if (rv != SECSuccess) {
goto loser;
}
if (version == TLS13_ECH_VERSION) {
rv = tls13_DecodeEchConfigContents(&tmp, &decodedConfig);
if (rv != SECSuccess) {
goto loser; /* code set */
}
if (decodedConfig) {
decodedConfig->version = version;
rv = SECITEM_MakeItem(NULL, &decodedConfig->raw, singleConfig.buf,
singleConfig.len);
if (rv != SECSuccess) {
goto loser;
}
PR_APPEND_LINK(&decodedConfig->link, configs);
decodedConfig = NULL;
}
}
}
return SECSuccess;
loser:
tls13_DestroyEchConfigs(configs);
return SECFailure;
}
/* Encode an ECHConfigList structure. We only create one config, and as the
* primary use for this function is to generate test inputs, we don't
* validate against what HPKE and libssl can actually support. */
SECStatus
SSLExp_EncodeEchConfigId(PRUint8 configId, const char *publicName, unsigned int maxNameLen,
HpkeKemId kemId, const SECKEYPublicKey *pubKey,
const HpkeSymmetricSuite *hpkeSuites, unsigned int hpkeSuiteCount,
PRUint8 *out, unsigned int *outlen, unsigned int maxlen)
{
SECStatus rv;
unsigned int savedOffset;
unsigned int len;
sslBuffer b = SSL_BUFFER_EMPTY;
PRUint8 tmpBuf[66]; // Large enough for an EC public key, currently only X25519.
unsigned int tmpLen;
if (!publicName || !hpkeSuites || hpkeSuiteCount == 0 ||
!pubKey || maxNameLen == 0 || !out || !outlen) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
/* ECHConfig ECHConfigList<1..2^16-1>; */
rv = sslBuffer_Skip(&b, 2, NULL);
if (rv != SECSuccess) {
goto loser;
}
/*
* struct {
* uint16 version;
* uint16 length;
* select (ECHConfig.version) {
* case 0xfe0d: ECHConfigContents contents;
* }
* } ECHConfig;
*/
rv = sslBuffer_AppendNumber(&b, TLS13_ECH_VERSION, 2);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_Skip(&b, 2, &savedOffset);
if (rv != SECSuccess) {
goto loser;
}
/*
* struct {
* uint8 config_id;
* HpkeKemId kem_id;
* HpkePublicKey public_key;
* HpkeSymmetricCipherSuite cipher_suites<4..2^16-4>;
* } HpkeKeyConfig;
*/
rv = sslBuffer_AppendNumber(&b, configId, 1);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendNumber(&b, kemId, 2);
if (rv != SECSuccess) {
goto loser;
}
rv = PK11_HPKE_Serialize(pubKey, tmpBuf, &tmpLen, sizeof(tmpBuf));
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendVariable(&b, tmpBuf, tmpLen, 2);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendNumber(&b, hpkeSuiteCount * 4, 2);
if (rv != SECSuccess) {
goto loser;
}
for (unsigned int i = 0; i < hpkeSuiteCount; i++) {
rv = sslBuffer_AppendNumber(&b, hpkeSuites[i].kdfId, 2);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendNumber(&b, hpkeSuites[i].aeadId, 2);
if (rv != SECSuccess) {
goto loser;
}
}
/*
* struct {
* HpkeKeyConfig key_config;
* uint8 maximum_name_length;
* opaque public_name<1..255>;
* Extension extensions<0..2^16-1>;
* } ECHConfigContents;
*/
rv = sslBuffer_AppendNumber(&b, maxNameLen, 1);
if (rv != SECSuccess) {
goto loser;
}
len = PORT_Strlen(publicName);
if (len > 0xff) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
goto loser;
}
rv = sslBuffer_AppendVariable(&b, (const PRUint8 *)publicName, len, 1);
if (rv != SECSuccess) {
goto loser;
}
/* extensions */
rv = sslBuffer_AppendNumber(&b, 0, 2);
if (rv != SECSuccess) {
goto loser;
}
/* Write the length now that we know it. */
rv = sslBuffer_InsertLength(&b, 0, 2);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_InsertLength(&b, savedOffset, 2);
if (rv != SECSuccess) {
goto loser;
}
if (SSL_BUFFER_LEN(&b) > maxlen) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
goto loser;
}
PORT_Memcpy(out, SSL_BUFFER_BASE(&b), SSL_BUFFER_LEN(&b));
*outlen = SSL_BUFFER_LEN(&b);
sslBuffer_Clear(&b);
return SECSuccess;
loser:
sslBuffer_Clear(&b);
return SECFailure;
}
SECStatus
SSLExp_GetEchRetryConfigs(PRFileDesc *fd, SECItem *retryConfigs)
{
SECStatus rv;
sslSocket *ss;
SECItem out = { siBuffer, NULL, 0 };
if (!fd || !retryConfigs) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
ss = ssl_FindSocket(fd);
if (!ss) {
SSL_DBG(("%d: SSL[%d]: bad socket in %s",
SSL_GETPID(), fd, __FUNCTION__));
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
/* We don't distinguish between "handshake completed
* without retry configs", and "handshake not completed".
* An application should only call this after receiving a
* RETRY_WITH_ECH error code, which implies retry_configs. */
if (!ss->xtnData.ech || !ss->xtnData.ech->retryConfigsValid) {
PORT_SetError(SSL_ERROR_HANDSHAKE_NOT_COMPLETED);
return SECFailure;
}
/* May be empty. */
rv = SECITEM_CopyItem(NULL, &out, &ss->xtnData.ech->retryConfigs);
if (rv == SECFailure) {
return SECFailure;
}
*retryConfigs = out;
return SECSuccess;
}
SECStatus
SSLExp_RemoveEchConfigs(PRFileDesc *fd)
{
sslSocket *ss;
if (!fd) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
ss = ssl_FindSocket(fd);
if (!ss) {
SSL_DBG(("%d: SSL[%d]: bad socket in %s",
SSL_GETPID(), fd, __FUNCTION__));
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
SECKEY_DestroyPrivateKey(ss->echPrivKey);
ss->echPrivKey = NULL;
SECKEY_DestroyPublicKey(ss->echPubKey);
ss->echPubKey = NULL;
tls13_DestroyEchConfigs(&ss->echConfigs);
/* Also remove any retry_configs and handshake context. */
if (ss->xtnData.ech && ss->xtnData.ech->retryConfigs.len) {
SECITEM_FreeItem(&ss->xtnData.ech->retryConfigs, PR_FALSE);
}
if (ss->ssl3.hs.echHpkeCtx) {
PK11_HPKE_DestroyContext(ss->ssl3.hs.echHpkeCtx, PR_TRUE);
ss->ssl3.hs.echHpkeCtx = NULL;
}
PORT_Free(CONST_CAST(char, ss->ssl3.hs.echPublicName));
ss->ssl3.hs.echPublicName = NULL;
return SECSuccess;
}
/* Import one or more ECHConfigs for the given keypair. The AEAD/KDF
* may differ , but only X25519 is supported for the KEM.*/
SECStatus
SSLExp_SetServerEchConfigs(PRFileDesc *fd,
const SECKEYPublicKey *pubKey, const SECKEYPrivateKey *privKey,
const PRUint8 *echConfigs, unsigned int echConfigsLen)
{
sslSocket *ss;
SECStatus rv;
SECItem data = { siBuffer, CONST_CAST(PRUint8, echConfigs), echConfigsLen };
if (!fd || !pubKey || !privKey || !echConfigs || echConfigsLen == 0) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
ss = ssl_FindSocket(fd);
if (!ss) {
SSL_DBG(("%d: SSL[%d]: bad socket in %s",
SSL_GETPID(), fd, __FUNCTION__));
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
if (IS_DTLS(ss)) {
return SECFailure;
}
/* Overwrite if we're already configured. */
rv = SSLExp_RemoveEchConfigs(fd);
if (rv != SECSuccess) {
return SECFailure;
}
rv = tls13_DecodeEchConfigs(&data, &ss->echConfigs);
if (rv != SECSuccess) {
goto loser;
}
if (PR_CLIST_IS_EMPTY(&ss->echConfigs)) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
goto loser;
}
ss->echPubKey = SECKEY_CopyPublicKey(pubKey);
if (!ss->echPubKey) {
goto loser;
}
ss->echPrivKey = SECKEY_CopyPrivateKey(privKey);
if (!ss->echPrivKey) {
goto loser;
}
return SECSuccess;
loser:
tls13_DestroyEchConfigs(&ss->echConfigs);
SECKEY_DestroyPrivateKey(ss->echPrivKey);
SECKEY_DestroyPublicKey(ss->echPubKey);
ss->echPubKey = NULL;
ss->echPrivKey = NULL;
return SECFailure;
}
/* Client enable. For now, we'll use the first
* compatible config (server preference). */
SECStatus
SSLExp_SetClientEchConfigs(PRFileDesc *fd,
const PRUint8 *echConfigs,
unsigned int echConfigsLen)
{
SECStatus rv;
sslSocket *ss;
SECItem data = { siBuffer, CONST_CAST(PRUint8, echConfigs), echConfigsLen };
if (!fd || !echConfigs || echConfigsLen == 0) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
ss = ssl_FindSocket(fd);
if (!ss) {
SSL_DBG(("%d: SSL[%d]: bad socket in %s",
SSL_GETPID(), fd, __FUNCTION__));
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
if (IS_DTLS(ss)) {
return SECFailure;
}
/* Overwrite if we're already configured. */
rv = SSLExp_RemoveEchConfigs(fd);
if (rv != SECSuccess) {
return SECFailure;
}
rv = tls13_DecodeEchConfigs(&data, &ss->echConfigs);
if (rv != SECSuccess) {
return SECFailure;
}
if (PR_CLIST_IS_EMPTY(&ss->echConfigs)) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
return SECSuccess;
}
/* Set up ECH. This generates an ephemeral sender
* keypair and the HPKE context */
SECStatus
tls13_ClientSetupEch(sslSocket *ss, sslClientHelloType type)
{
SECStatus rv;
HpkeContext *cx = NULL;
SECKEYPublicKey *pkR = NULL;
SECItem hpkeInfo = { siBuffer, NULL, 0 };
sslEchConfig *cfg = NULL;
if (PR_CLIST_IS_EMPTY(&ss->echConfigs) ||
!ssl_ShouldSendSNIExtension(ss, ss->url) ||
IS_DTLS(ss)) {
return SECSuccess;
}
/* Maybe apply our own priority if >1. For now, we only support
* one version and one KEM. Each ECHConfig can specify multiple
* KDF/AEADs, so just use the first. */
cfg = (sslEchConfig *)PR_LIST_HEAD(&ss->echConfigs);
SSL_TRC(50, ("%d: TLS13[%d]: Setup client ECH",
SSL_GETPID(), ss->fd));
switch (type) {
case client_hello_initial:
PORT_Assert(!ss->ssl3.hs.echHpkeCtx && !ss->ssl3.hs.echPublicName);
cx = PK11_HPKE_NewContext(cfg->contents.kemId, cfg->contents.kdfId,
cfg->contents.aeadId, NULL, NULL);
break;
case client_hello_retry:
if (!ss->ssl3.hs.echHpkeCtx || !ss->ssl3.hs.echPublicName) {
FATAL_ERROR(ss, SEC_ERROR_LIBRARY_FAILURE, internal_error);
return SECFailure;
}
/* Nothing else to do. */
return SECSuccess;
default:
PORT_Assert(0);
goto loser;
}
if (!cx) {
goto loser;
}
rv = PK11_HPKE_Deserialize(cx, cfg->contents.publicKey.data, cfg->contents.publicKey.len, &pkR);
if (rv != SECSuccess) {
goto loser;
}
if (!SECITEM_AllocItem(NULL, &hpkeInfo, strlen(kHpkeInfoEch) + 1 + cfg->raw.len)) {
goto loser;
}
PORT_Memcpy(&hpkeInfo.data[0], kHpkeInfoEch, strlen(kHpkeInfoEch));
PORT_Memset(&hpkeInfo.data[strlen(kHpkeInfoEch)], 0, 1);
PORT_Memcpy(&hpkeInfo.data[strlen(kHpkeInfoEch) + 1], cfg->raw.data, cfg->raw.len);
PRINT_BUF(50, (ss, "Info", hpkeInfo.data, hpkeInfo.len));
/* Setup with an ephemeral sender keypair. */
rv = PK11_HPKE_SetupS(cx, NULL, NULL, pkR, &hpkeInfo);
if (rv != SECSuccess) {
goto loser;
}
rv = ssl3_GetNewRandom(ss->ssl3.hs.client_inner_random);
if (rv != SECSuccess) {
goto loser; /* code set */
}
/* If ECH is rejected, the application will use SSLChannelInfo
* to fetch this field and perform cert chain verification. */
ss->ssl3.hs.echPublicName = PORT_Strdup(cfg->contents.publicName);
if (!ss->ssl3.hs.echPublicName) {
goto loser;
}
ss->ssl3.hs.echHpkeCtx = cx;
SECKEY_DestroyPublicKey(pkR);
SECITEM_FreeItem(&hpkeInfo, PR_FALSE);
return SECSuccess;
loser:
PK11_HPKE_DestroyContext(cx, PR_TRUE);
SECKEY_DestroyPublicKey(pkR);
SECITEM_FreeItem(&hpkeInfo, PR_FALSE);
PORT_Assert(PORT_GetError() != 0);
return SECFailure;
}
/*
* outerAAD - The associated data for the AEAD (the entire client hello with the ECH payload zeroed)
* chInner - The plaintext which will be encrypted (the ClientHelloInner plus padding)
* echPayload - Output location. A buffer containing all-zeroes of at least chInner->len + TLS13_ECH_AEAD_TAG_LEN bytes.
*
* echPayload may point into outerAAD to avoid the need to duplicate the ClientHelloOuter buffer.
*/
static SECStatus
tls13_EncryptClientHello(sslSocket *ss, SECItem *aadItem, const sslBuffer *chInner, PRUint8 *echPayload)
{
SECStatus rv;
SECItem chPt = { siBuffer, chInner->buf, chInner->len };
SECItem *chCt = NULL;
PRINT_BUF(50, (ss, "aad for ECH Encrypt", aadItem->data, aadItem->len));
PRINT_BUF(50, (ss, "plaintext for ECH Encrypt", chInner->buf, chInner->len));
#ifndef UNSAFE_FUZZER_MODE
rv = PK11_HPKE_Seal(ss->ssl3.hs.echHpkeCtx, aadItem, &chPt, &chCt);
if (rv != SECSuccess) {
goto loser;
}
PRINT_BUF(50, (ss, "ciphertext from ECH Encrypt", chCt->data, chCt->len));
#else
/* Fake a tag. */
SECITEM_AllocItem(NULL, chCt, chPt.len + TLS13_ECH_AEAD_TAG_LEN);
if (!chCt) {
goto loser;
}
PORT_Memcpy(chCt->data, chPt.data, chPt.len);
#endif
#ifdef DEBUG
/* When encrypting in-place, the payload is part of the AAD and must be zeroed. */
PRUint8 val = 0;
for (int i = 0; i < chCt->len; i++) {
val |= *(echPayload + i);
}
PRINT_BUF(100, (ss, "Empty Placeholder for output of ECH Encryption", echPayload, chCt->len));
PR_ASSERT(val == 0);
#endif
PORT_Memcpy(echPayload, chCt->data, chCt->len);
SECITEM_FreeItem(chCt, PR_TRUE);
return SECSuccess;
loser:
SECITEM_FreeItem(chCt, PR_TRUE);
return SECFailure;
}
SECStatus
tls13_GetMatchingEchConfigs(const sslSocket *ss, HpkeKdfId kdf, HpkeAeadId aead,
const PRUint8 configId, const sslEchConfig *cur, sslEchConfig **next)
{
SSL_TRC(50, ("%d: TLS13[%d]: GetMatchingEchConfig %d",
SSL_GETPID(), ss->fd, configId));
/* If |cur|, resume the search at that node, else the list head. */
for (PRCList *cur_p = cur ? ((PRCList *)cur)->next : PR_LIST_HEAD(&ss->echConfigs);
cur_p != &ss->echConfigs;
cur_p = PR_NEXT_LINK(cur_p)) {
sslEchConfig *echConfig = (sslEchConfig *)cur_p;
if (echConfig->contents.configId == configId &&
echConfig->contents.aeadId == aead &&
echConfig->contents.kdfId == kdf) {
*next = echConfig;
return SECSuccess;
}
}
*next = NULL;
return SECSuccess;
}
/* Given a CH with extensions, copy from the start up to the extensions
* into |writer| and return the extensions themselves in |extensions|.
* If |explicitSid|, place this value into |writer| as the SID. Else,
* the sid is copied from |reader| to |writer|. */
static SECStatus
tls13_CopyChPreamble(sslSocket *ss, sslReader *reader, const SECItem *explicitSid, sslBuffer *writer, sslReadBuffer *extensions)
{
SECStatus rv;
sslReadBuffer tmpReadBuf;
/* Locate the extensions. */
rv = sslRead_Read(reader, 2 + SSL3_RANDOM_LENGTH, &tmpReadBuf);
if (rv != SECSuccess) {
return SECFailure;
}
rv = sslBuffer_Append(writer, tmpReadBuf.buf, tmpReadBuf.len);
if (rv != SECSuccess) {
return SECFailure;
}
/* legacy_session_id */
rv = sslRead_ReadVariable(reader, 1, &tmpReadBuf);
if (explicitSid) {
/* Encoded SID should be empty when copying from CHOuter. */
if (tmpReadBuf.len > 0) {
PORT_SetError(SSL_ERROR_RX_MALFORMED_ECH_EXTENSION);
return SECFailure;
}
rv = sslBuffer_AppendVariable(writer, explicitSid->data, explicitSid->len, 1);
} else {
rv = sslBuffer_AppendVariable(writer, tmpReadBuf.buf, tmpReadBuf.len, 1);
}
if (rv != SECSuccess) {
return SECFailure;
}
/* cipher suites */
rv = sslRead_ReadVariable(reader, 2, &tmpReadBuf);
if (rv != SECSuccess) {
return SECFailure;
}
rv = sslBuffer_AppendVariable(writer, tmpReadBuf.buf, tmpReadBuf.len, 2);
if (rv != SECSuccess) {
return SECFailure;
}
/* compression */
rv = sslRead_ReadVariable(reader, 1, &tmpReadBuf);
if (rv != SECSuccess) {
return SECFailure;
}
rv = sslBuffer_AppendVariable(writer, tmpReadBuf.buf, tmpReadBuf.len, 1);
if (rv != SECSuccess) {
return SECFailure;
}
/* extensions */
rv = sslRead_ReadVariable(reader, 2, extensions);
if (rv != SECSuccess) {
return SECFailure;
}
/* padding (optional) */
sslReadBuffer padding;
rv = sslRead_Read(reader, SSL_READER_REMAINING(reader), &padding);
if (rv != SECSuccess) {
return SECFailure;
}
PRUint8 result = 0;
for (int i = 0; i < padding.len; i++) {
result |= padding.buf[i];
}
if (result) {
SSL_TRC(50, ("%d: TLS13: Invalid ECH ClientHelloInner padding decoded", SSL_GETPID()));
FATAL_ERROR(ss, SSL_ERROR_RX_MALFORMED_ECH_EXTENSION, illegal_parameter);
return SECFailure;
}
return SECSuccess;
}
/*
* The ClientHelloOuterAAD is a serialized ClientHello structure, defined in
* Section 4.1.2 of [RFC8446], which matches the ClientHelloOuter except the
* payload field of the "encrypted_client_hello" is replaced with a byte
* string of the same length but whose contents are zeros. This value does
* not include the four-byte header from the Handshake structure.
*/
static SECStatus
tls13_ServerMakeChOuterAAD(sslSocket *ss, const PRUint8 *outerCh, unsigned int outerChLen, SECItem *outerAAD)
{
SECStatus rv;
sslBuffer aad = SSL_BUFFER_EMPTY;
const unsigned int echPayloadLen = ss->xtnData.ech->innerCh.len; /* Length of incoming payload */
const unsigned int echPayloadOffset = ss->xtnData.ech->payloadStart - outerCh; /* Offset from start of CHO */
PORT_Assert(outerChLen > echPayloadLen);
PORT_Assert(echPayloadOffset + echPayloadLen <= outerChLen);
PORT_Assert(ss->sec.isServer);
PORT_Assert(ss->xtnData.ech);
#ifdef DEBUG
/* Safety check that payload length pointed to by offset matches expected length */
sslReader echXtnReader = SSL_READER(outerCh + echPayloadOffset - 2, 2);
PRUint64 parsedXtnSize;
rv = sslRead_ReadNumber(&echXtnReader, 2, &parsedXtnSize);
PR_ASSERT(rv == SECSuccess);
PR_ASSERT(parsedXtnSize == echPayloadLen);
#endif
rv = sslBuffer_Append(&aad, outerCh, outerChLen);
if (rv != SECSuccess) {
goto loser;
}
PORT_Memset(aad.buf + echPayloadOffset, 0, echPayloadLen);
PRINT_BUF(50, (ss, "AAD for ECH Decryption", aad.buf, aad.len));
outerAAD->data = aad.buf;
outerAAD->len = aad.len;
return SECSuccess;
loser:
sslBuffer_Clear(&aad);
return SECFailure;
}
SECStatus
tls13_OpenClientHelloInner(sslSocket *ss, const SECItem *outer, const SECItem *outerAAD, sslEchConfig *cfg, SECItem **chInner)
{
SECStatus rv;
HpkeContext *cx = NULL;
SECItem *decryptedChInner = NULL;
SECItem hpkeInfo = { siBuffer, NULL, 0 };
SSL_TRC(50, ("%d: TLS13[%d]: Server opening ECH Inner%s", SSL_GETPID(),
ss->fd, ss->ssl3.hs.helloRetry ? " after HRR" : ""));
if (!ss->ssl3.hs.helloRetry) {
PORT_Assert(!ss->ssl3.hs.echHpkeCtx);
cx = PK11_HPKE_NewContext(cfg->contents.kemId, cfg->contents.kdfId,
cfg->contents.aeadId, NULL, NULL);
if (!cx) {
goto loser;
}
if (!SECITEM_AllocItem(NULL, &hpkeInfo, strlen(kHpkeInfoEch) + 1 + cfg->raw.len)) {
goto loser;
}
PORT_Memcpy(&hpkeInfo.data[0], kHpkeInfoEch, strlen(kHpkeInfoEch));
PORT_Memset(&hpkeInfo.data[strlen(kHpkeInfoEch)], 0, 1);
PORT_Memcpy(&hpkeInfo.data[strlen(kHpkeInfoEch) + 1], cfg->raw.data, cfg->raw.len);
rv = PK11_HPKE_SetupR(cx, ss->echPubKey, ss->echPrivKey,
&ss->xtnData.ech->senderPubKey, &hpkeInfo);
if (rv != SECSuccess) {
goto loser; /* code set */
}
} else {
PORT_Assert(ss->ssl3.hs.echHpkeCtx);
cx = ss->ssl3.hs.echHpkeCtx;
}
#ifndef UNSAFE_FUZZER_MODE
rv = PK11_HPKE_Open(cx, outerAAD, &ss->xtnData.ech->innerCh, &decryptedChInner);
if (rv != SECSuccess) {
SSL_TRC(10, ("%d: SSL3[%d]: Failed to decrypt inner CH with this candidate",
SSL_GETPID(), ss->fd));
goto loser; /* code set */
}
#else
rv = SECITEM_CopyItem(NULL, decryptedChInner, &ss->xtnData.ech->innerCh);
if (rv != SECSuccess) {
goto loser;
}
decryptedChInner->len -= TLS13_ECH_AEAD_TAG_LEN; /* Fake tag */
#endif
/* Stash the context, we may need it for HRR. */
ss->ssl3.hs.echHpkeCtx = cx;
*chInner = decryptedChInner;
PRINT_BUF(100, (ss, "Decrypted ECH Inner", decryptedChInner->data, decryptedChInner->len));
SECITEM_FreeItem(&hpkeInfo, PR_FALSE);
return SECSuccess;
loser:
SECITEM_FreeItem(decryptedChInner, PR_TRUE);
SECITEM_FreeItem(&hpkeInfo, PR_FALSE);
if (cx != ss->ssl3.hs.echHpkeCtx) {
/* Don't double-free if it's already global. */
PK11_HPKE_DestroyContext(cx, PR_TRUE);
}
return SECFailure;
}
/* This is the maximum number of extension hooks that the following functions can handle. */
#define MAX_EXTENSION_WRITERS 32
static SECStatus
tls13_WriteDupXtnsToChInner(PRBool compressing, sslBuffer *dupXtns, sslBuffer *chInnerXtns)
{
SECStatus rv;
if (compressing && SSL_BUFFER_LEN(dupXtns) > 0) {
rv = sslBuffer_AppendNumber(chInnerXtns, ssl_tls13_outer_extensions_xtn, 2);
if (rv != SECSuccess) {
return SECFailure;
}
rv = sslBuffer_AppendNumber(chInnerXtns, dupXtns->len + 1, 2);
if (rv != SECSuccess) {
return SECFailure;
}
rv = sslBuffer_AppendBufferVariable(chInnerXtns, dupXtns, 1);
if (rv != SECSuccess) {
return SECFailure;
}
} else {
/* dupXtns carries whole extensions with lengths on each. */
rv = sslBuffer_AppendBuffer(chInnerXtns, dupXtns);
if (rv != SECSuccess) {
return SECFailure;
}
}
sslBuffer_Clear(dupXtns);
return SECSuccess;
}
/* Add ordinary extensions to CHInner.
* The value of the extension from CHOuter is in |extensionData|.
*
* If the value is to be compressed, it is written to |dupXtns|.
* Otherwise, a full extension is written to |chInnerXtns|.
*
* This function is always called twice:
* once without compression and once with compression if possible.
*
* Because we want to allow extensions that did not appear in CHOuter
* to be included in CHInner, we also need to track which extensions
* have been included. This is what |called| and |nCalled| track.
*/
static SECStatus
tls13_ChInnerAppendExtension(sslSocket *ss, PRUint16 extensionType,
const sslReadBuffer *extensionData,
sslBuffer *dupXtns, sslBuffer *chInnerXtns,
PRBool compressing,
PRUint16 *called, unsigned int *nCalled)
{
PRUint8 buf[1024] = { 0 };
const PRUint8 *p;
unsigned int len = 0;
PRBool willCompress;
PORT_Assert(extensionType != ssl_tls13_encrypted_client_hello_xtn);
sslCustomExtensionHooks *hook = ss->opt.callExtensionWriterOnEchInner
? ssl_FindCustomExtensionHooks(ss, extensionType)
: NULL;
if (hook && hook->writer) {
if (*nCalled >= MAX_EXTENSION_WRITERS) {
PORT_SetError(SEC_ERROR_LIBRARY_FAILURE); /* TODO new code? */
return SECFailure;
}
PRBool append = (*hook->writer)(ss->fd, ssl_hs_client_hello,
buf, &len, sizeof(buf), hook->writerArg);
called[(*nCalled)++] = extensionType;
if (!append) {
/* This extension is not going to appear in CHInner. */
/* TODO: consider removing this extension from ss->xtnData.advertised.
* The consequence of not removing it is that we won't complain
* if the server accepts ECH and then includes this extension.
* The cost is a complete reworking of ss->xtnData.advertised.
*/
return SECSuccess;
}
/* It can be compressed if it is the same as the outer value. */
willCompress = (len == extensionData->len &&
NSS_SecureMemcmp(buf, extensionData->buf, len) == 0);
p = buf;
} else {
/* Non-custom extensions are duplicated when compressing. */
willCompress = PR_TRUE;
p = extensionData->buf;
len = extensionData->len;
}
/* Duplicated extensions all need to go together. */
sslBuffer *dst = willCompress ? dupXtns : chInnerXtns;
SECStatus rv = sslBuffer_AppendNumber(dst, extensionType, 2);
if (rv != SECSuccess) {
return SECFailure;
}
if (!willCompress || !compressing) {
rv = sslBuffer_AppendVariable(dst, p, len, 2);
if (rv != SECSuccess) {
return SECFailure;
}
}
/* As this function is called twice, we only want to update our state the second time. */
if (compressing) {
ss->xtnData.echAdvertised[ss->xtnData.echNumAdvertised++] = extensionType;
SSL_TRC(50, ("Appending extension=%d to the Client Hello Inner. Compressed?=%d", extensionType, willCompress));
}
return SECSuccess;
}
/* Call any custom extension handlers that didn't want to be added to CHOuter. */
static SECStatus
tls13_ChInnerAdditionalExtensionWriters(sslSocket *ss, const PRUint16 *called,
unsigned int nCalled, sslBuffer *chInnerXtns)
{
if (!ss->opt.callExtensionWriterOnEchInner) {
return SECSuccess;
}
for (PRCList *cursor = PR_NEXT_LINK(&ss->extensionHooks);
cursor != &ss->extensionHooks;
cursor = PR_NEXT_LINK(cursor)) {
sslCustomExtensionHooks *hook = (sslCustomExtensionHooks *)cursor;
/* Skip if this hook was already called. */
PRBool hookCalled = PR_FALSE;
for (unsigned int i = 0; i < nCalled; ++i) {
if (called[i] == hook->type) {
hookCalled = PR_TRUE;
break;
}
}
if (hookCalled) {
continue;
}
/* This is a cut-down version of ssl_CallCustomExtensionSenders(). */
PRUint8 buf[1024];
unsigned int len = 0;
PRBool append = (*hook->writer)(ss->fd, ssl_hs_client_hello,
buf, &len, sizeof(buf), hook->writerArg);
if (!append) {
continue;
}
SECStatus rv = sslBuffer_AppendNumber(chInnerXtns, hook->type, 2);
if (rv != SECSuccess) {
return SECFailure;
}
rv = sslBuffer_AppendVariable(chInnerXtns, buf, len, 2);
if (rv != SECSuccess) {
return SECFailure;
}
ss->xtnData.echAdvertised[ss->xtnData.echNumAdvertised++] = hook->type;
}
return SECSuccess;
}
/* Take the PSK extension CHOuter and fill it with junk. */
static SECStatus
tls13_RandomizePsk(PRUint8 *buf, unsigned int len)
{
sslReader rdr = SSL_READER(buf, len);
/* Read the length of identities. */
PRUint64 outerLen = 0;
SECStatus rv = sslRead_ReadNumber(&rdr, 2, &outerLen);
if (rv != SECSuccess) {
return SECFailure;
}
PORT_Assert(outerLen < len + 2);
/* Read the length of PskIdentity.identity */
PRUint64 innerLen = 0;
rv = sslRead_ReadNumber(&rdr, 2, &innerLen);
if (rv != SECSuccess) {
return SECFailure;
}
/* identities should contain just one identity. */
PORT_Assert(outerLen == innerLen + 6);
/* Randomize PskIdentity.{identity,obfuscated_ticket_age}. */
rv = PK11_GenerateRandom(buf + rdr.offset, innerLen + 4);
if (rv != SECSuccess) {
return SECFailure;
}
rdr.offset += innerLen + 4;
/* Read the length of binders. */
rv = sslRead_ReadNumber(&rdr, 2, &outerLen);
if (rv != SECSuccess) {
return SECFailure;
}
PORT_Assert(outerLen + rdr.offset == len);
/* Read the length of the binder. */
rv = sslRead_ReadNumber(&rdr, 1, &innerLen);
if (rv != SECSuccess) {
return SECFailure;
}
/* binders should contain just one binder. */
PORT_Assert(outerLen == innerLen + 1);
/* Randomize the binder. */
rv = PK11_GenerateRandom(buf + rdr.offset, innerLen);
if (rv != SECSuccess) {
return SECFailure;
}
return SECSuccess;
}
/* Given a buffer of extensions prepared for CHOuter, translate those extensions to a
* buffer suitable for CHInner. This is intended to be called twice: once without
* compression for the transcript hash and binders, and once with compression for
* encoding the actual CHInner value.
*
* Compressed extensions are moved in both runs. When compressing, they are moved
* to a single outer_extensions extension, which lists extensions from CHOuter.
* When not compressing, this produces the ClientHello that will be reconstructed
* from the compressed ClientHello (that is, what goes into the handshake transcript),
* so all the compressed extensions need to appear in the same place that the
* outer_extensions extension appears.
*
* On the first run, if |inOutPskXtn| and OuterXtnsBuf contains a PSK extension,
* remove it and return in the outparam.he caller will compute the binder value
* based on the uncompressed output. Next, if |compress|, consolidate duplicated
* extensions (that would otherwise be copied) into a single outer_extensions
* extension. If |inOutPskXtn|, the extension contains a binder, it is appended
* after the deduplicated outer_extensions. In the case of GREASE ECH, one call
* is made to estimate size (wiith compression, null inOutPskXtn).
*/
SECStatus
tls13_ConstructInnerExtensionsFromOuter(sslSocket *ss, sslBuffer *chOuterXtnsBuf,
sslBuffer *chInnerXtns, sslBuffer *inOutPskXtn,
PRBool shouldCompress)
{
SECStatus rv;
PRUint64 extensionType;
sslReadBuffer extensionData;
sslBuffer pskXtn = SSL_BUFFER_EMPTY;
sslBuffer dupXtns = SSL_BUFFER_EMPTY; /* Duplicated extensions, types-only if |compress|. */
unsigned int tmpOffset;
unsigned int tmpLen;
unsigned int srcXtnBase; /* To truncate CHOuter and remove the PSK extension. */
PRUint16 called[MAX_EXTENSION_WRITERS] = { 0 }; /* For tracking which has been called. */
unsigned int nCalled = 0;
SSL_TRC(50, ("%d: TLS13[%d]: Constructing ECH inner extensions %s compression",
SSL_GETPID(), ss->fd, shouldCompress ? "with" : "without"));
/* When offering the "encrypted_client_hello" extension in its
* ClientHelloOuter, the client MUST also offer an empty
* "encrypted_client_hello" extension in its ClientHelloInner. */
rv = sslBuffer_AppendNumber(chInnerXtns, ssl_tls13_encrypted_client_hello_xtn, 2);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendNumber(chInnerXtns, 1, 2);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendNumber(chInnerXtns, ech_xtn_type_inner, 1);
if (rv != SECSuccess) {
goto loser;
}
sslReader rdr = SSL_READER(chOuterXtnsBuf->buf, chOuterXtnsBuf->len);
while (SSL_READER_REMAINING(&rdr)) {
srcXtnBase = rdr.offset;
rv = sslRead_ReadNumber(&rdr, 2, &extensionType);
if (rv != SECSuccess) {
goto loser;
}
/* Get the extension data. */
rv = sslRead_ReadVariable(&rdr, 2, &extensionData);
if (rv != SECSuccess) {
goto loser;
}
/* Skip extensions that are TLS < 1.3 only, since CHInner MUST
* negotiate TLS 1.3 or above.
* If the extension is supported by default (sslSupported) but unknown
* to TLS 1.3 it must be a TLS < 1.3 only extension. */
SSLExtensionSupport sslSupported;
(void)SSLExp_GetExtensionSupport(extensionType, &sslSupported);
if (sslSupported != ssl_ext_none &&
tls13_ExtensionStatus(extensionType, ssl_hs_client_hello) == tls13_extension_unknown) {
continue;
}
switch (extensionType) {
case ssl_server_name_xtn:
/* Write the real (private) SNI value. */
rv = sslBuffer_AppendNumber(chInnerXtns, extensionType, 2);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_Skip(chInnerXtns, 2, &tmpOffset);
if (rv != SECSuccess) {
goto loser;
}
tmpLen = SSL_BUFFER_LEN(chInnerXtns);
rv = ssl3_ClientFormatServerNameXtn(ss, ss->url,
strlen(ss->url),
NULL, chInnerXtns);
if (rv != SECSuccess) {
goto loser;
}
tmpLen = SSL_BUFFER_LEN(chInnerXtns) - tmpLen;
rv = sslBuffer_InsertNumber(chInnerXtns, tmpOffset, tmpLen, 2);
if (rv != SECSuccess) {
goto loser;
}
/* Only update state on second invocation of this function */
if (shouldCompress) {
ss->xtnData.echAdvertised[ss->xtnData.echNumAdvertised++] = extensionType;
}
break;
case ssl_tls13_supported_versions_xtn:
/* Only TLS 1.3 and GREASE on CHInner. */
rv = sslBuffer_AppendNumber(chInnerXtns, extensionType, 2);
if (rv != SECSuccess) {
goto loser;
}
/* Extension length. */
tmpLen = (ss->opt.enableGrease) ? 5 : 3;
rv = sslBuffer_AppendNumber(chInnerXtns, tmpLen, 2);
if (rv != SECSuccess) {
goto loser;
}
/* ProtocolVersion length */
rv = sslBuffer_AppendNumber(chInnerXtns, tmpLen - 1, 1);
if (rv != SECSuccess) {
goto loser;
}
/* ProtocolVersion TLS 1.3 */
rv = sslBuffer_AppendNumber(chInnerXtns, SSL_LIBRARY_VERSION_TLS_1_3, 2);
if (rv != SECSuccess) {
goto loser;
}
/* ProtocolVersion GREASE */
if (ss->opt.enableGrease) {
rv = sslBuffer_AppendNumber(chInnerXtns, ss->ssl3.hs.grease->idx[grease_version], 2);
if (rv != SECSuccess) {
goto loser;
}
}
/* Only update state on second invocation of this function */
if (shouldCompress) {
ss->xtnData.echAdvertised[ss->xtnData.echNumAdvertised++] = extensionType;
}
break;
case ssl_tls13_pre_shared_key_xtn:
if (inOutPskXtn && !shouldCompress) {
rv = sslBuffer_AppendNumber(&pskXtn, extensionType, 2);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendVariable(&pskXtn, extensionData.buf,
extensionData.len, 2);
if (rv != SECSuccess) {
goto loser;
}
/* This should be the last extension. */
PORT_Assert(srcXtnBase == ss->xtnData.lastXtnOffset);
PORT_Assert(chOuterXtnsBuf->len - srcXtnBase == extensionData.len + 4);
rv = tls13_RandomizePsk(chOuterXtnsBuf->buf + srcXtnBase + 4,
chOuterXtnsBuf->len - srcXtnBase - 4);
if (rv != SECSuccess) {
goto loser;
}
} else if (!inOutPskXtn) {
/* When GREASEing, only the length is used.
* Order doesn't matter, so just copy the extension. */
rv = sslBuffer_AppendNumber(chInnerXtns, extensionType, 2);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendVariable(chInnerXtns, extensionData.buf,
extensionData.len, 2);
if (rv != SECSuccess) {
goto loser;
}
}
/* Only update state on second invocation of this function */
if (shouldCompress) {
ss->xtnData.echAdvertised[ss->xtnData.echNumAdvertised++] = extensionType;
}
break;
default: {
/* This is a regular extension. We can maybe compress these. */
rv = tls13_ChInnerAppendExtension(ss, extensionType,
&extensionData,
&dupXtns, chInnerXtns,
shouldCompress,
called, &nCalled);
if (rv != SECSuccess) {
goto loser;
}
break;
}
}
}
rv = tls13_WriteDupXtnsToChInner(shouldCompress, &dupXtns, chInnerXtns);
if (rv != SECSuccess) {
goto loser;
}
/* Now call custom extension handlers that didn't choose to append anything to
* the outer ClientHello. */
rv = tls13_ChInnerAdditionalExtensionWriters(ss, called, nCalled, chInnerXtns);
if (rv != SECSuccess) {
goto loser;
}
if (inOutPskXtn) {
/* On the first, non-compress run, append the (bad) PSK binder.
* On the second compression run, the caller is responsible for
* providing an extension with a valid binder, so append that. */
if (shouldCompress) {
rv = sslBuffer_AppendBuffer(chInnerXtns, inOutPskXtn);
} else {
rv = sslBuffer_AppendBuffer(chInnerXtns, &pskXtn);
*inOutPskXtn = pskXtn;
}
if (rv != SECSuccess) {
goto loser;
}
}
return SECSuccess;
loser:
sslBuffer_Clear(&pskXtn);
sslBuffer_Clear(&dupXtns);
return SECFailure;
}
static SECStatus
tls13_EncodeClientHelloInner(sslSocket *ss, const sslBuffer *chInner, const sslBuffer *chInnerXtns, sslBuffer *out)
{
PORT_Assert(ss && chInner && chInnerXtns && out);
SECStatus rv;
sslReadBuffer tmpReadBuf;
sslReader chReader = SSL_READER(chInner->buf, chInner->len);
rv = sslRead_Read(&chReader, 4, &tmpReadBuf);
if (rv != SECSuccess) {
goto loser;
}
rv = sslRead_Read(&chReader, 2 + SSL3_RANDOM_LENGTH, &tmpReadBuf);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_Append(out, tmpReadBuf.buf, tmpReadBuf.len);
if (rv != SECSuccess) {
goto loser;
}
/* Skip the legacy_session_id */
rv = sslRead_ReadVariable(&chReader, 1, &tmpReadBuf);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendNumber(out, 0, 1);
if (rv != SECSuccess) {
goto loser;
}
/* cipher suites */
rv = sslRead_ReadVariable(&chReader, 2, &tmpReadBuf);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendVariable(out, tmpReadBuf.buf, tmpReadBuf.len, 2);
if (rv != SECSuccess) {
goto loser;
}
/* compression methods */
rv = sslRead_ReadVariable(&chReader, 1, &tmpReadBuf);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendVariable(out, tmpReadBuf.buf, tmpReadBuf.len, 1);
if (rv != SECSuccess) {
goto loser;
}
/* Append the extensions. */
rv = sslBuffer_AppendBufferVariable(out, chInnerXtns, 2);
if (rv != SECSuccess) {
goto loser;
}
return SECSuccess;
loser:
sslBuffer_Clear(out);
return SECFailure;
}
SECStatus
tls13_PadChInner(sslBuffer *chInner, uint8_t maxNameLen, uint8_t serverNameLen)
{
SECStatus rv;
PORT_Assert(chInner);
PORT_Assert(serverNameLen > 0);
static unsigned char padding[256 + 32] = { 0 };
int16_t name_padding = (int16_t)maxNameLen - (int16_t)serverNameLen;
if (name_padding < 0) {
name_padding = 0;
}
unsigned int rounding_padding = 31 - ((SSL_BUFFER_LEN(chInner) + name_padding) % 32);
unsigned int total_padding = name_padding + rounding_padding;
PORT_Assert(total_padding < sizeof(padding));
SSL_TRC(100, ("computed ECH Inner Client Hello padding of size %u", total_padding));
rv = sslBuffer_Append(chInner, padding, total_padding);
if (rv != SECSuccess) {
sslBuffer_Clear(chInner);
return SECFailure;
}
return SECSuccess;
}
/* Build an ECH Xtn body with a zeroed payload for the client hello inner
*
* enum { outer(0), inner(1) } ECHClientHelloType;
*
* struct {
* ECHClientHelloType type;
* select (ECHClientHello.type) {
* case outer:
* HpkeSymmetricCipherSuite cipher_suite;
* uint8 config_id;
* opaque enc<0..2^16-1>;
* opaque payload<1..2^16-1>;
* case inner:
* Empty;
* };
* } ECHClientHello;
*
* payloadLen = Size of zeroed placeholder field for payload.
* payloadOffset = Out parameter, start of payload field
* echXtn = Out parameter, constructed ECH Xtn with zeroed placeholder field.
*/
SECStatus
tls13_BuildEchXtn(sslEchConfig *cfg, const SECItem *hpkeEnc, unsigned int payloadLen, PRUint16 *payloadOffset, sslBuffer *echXtn)
{
SECStatus rv;
/* Format the encrypted_client_hello extension. */
rv = sslBuffer_AppendNumber(echXtn, ech_xtn_type_outer, 1);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendNumber(echXtn, cfg->contents.kdfId, 2);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendNumber(echXtn, cfg->contents.aeadId, 2);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendNumber(echXtn, cfg->contents.configId, 1);
if (rv != SECSuccess) {
goto loser;
}
if (hpkeEnc) {
/* Public Key */
rv = sslBuffer_AppendVariable(echXtn, hpkeEnc->data, hpkeEnc->len, 2);
if (rv != SECSuccess) {
goto loser;
}
} else {
/* |enc| is empty. */
rv = sslBuffer_AppendNumber(echXtn, 0, 2);
if (rv != SECSuccess) {
goto loser;
}
}
payloadLen += TLS13_ECH_AEAD_TAG_LEN;
rv = sslBuffer_AppendNumber(echXtn, payloadLen, 2);
if (rv != SECSuccess) {
goto loser;
}
*payloadOffset = echXtn->len;
rv = sslBuffer_Fill(echXtn, 0, payloadLen);
if (rv != SECSuccess) {
goto loser;
}
PRINT_BUF(100, (NULL, "ECH Xtn with Placeholder:", echXtn->buf, echXtn->len));
return SECSuccess;
loser:
sslBuffer_Clear(echXtn);
return SECFailure;
}
SECStatus
tls13_ConstructClientHelloWithEch(sslSocket *ss, const sslSessionID *sid, PRBool freshSid,
sslBuffer *chOuter, sslBuffer *chOuterXtnsBuf)
{
SECStatus rv;
sslBuffer chInner = SSL_BUFFER_EMPTY;
sslBuffer encodedChInner = SSL_BUFFER_EMPTY;
sslBuffer paddingChInner = SSL_BUFFER_EMPTY;
sslBuffer chInnerXtns = SSL_BUFFER_EMPTY;
sslBuffer pskXtn = SSL_BUFFER_EMPTY;
unsigned int preambleLen;
SSL_TRC(50, ("%d: TLS13[%d]: Constructing ECH inner", SSL_GETPID(), ss->fd));
/* Create the full (uncompressed) inner extensions and steal any PSK extension.
* NB: Neither chOuterXtnsBuf nor chInnerXtns are length-prefixed. */
rv = tls13_ConstructInnerExtensionsFromOuter(ss, chOuterXtnsBuf, &chInnerXtns,
&pskXtn, PR_FALSE);
if (rv != SECSuccess) {
goto loser; /* code set */
}
rv = ssl3_CreateClientHelloPreamble(ss, sid, PR_FALSE, SSL_LIBRARY_VERSION_TLS_1_3,
PR_TRUE, &chInnerXtns, &chInner);
if (rv != SECSuccess) {
goto loser; /* code set */
}
preambleLen = SSL_BUFFER_LEN(&chInner);
/* Write handshake header length. tls13_EncryptClientHello will
* remove this upon encoding, but the transcript needs it. This assumes
* the 4B stream-variant header. */
PORT_Assert(!IS_DTLS(ss));
rv = sslBuffer_InsertNumber(&chInner, 1,
chInner.len + 2 + chInnerXtns.len - 4, 3);
if (rv != SECSuccess) {
goto loser;
}
if (pskXtn.len) {
PORT_Assert(ssl3_ExtensionAdvertised(ss, ssl_tls13_pre_shared_key_xtn));
rv = tls13_WriteExtensionsWithBinder(ss, &chInnerXtns, &chInner);
/* Update the stolen PSK extension with the binder value. */
PORT_Memcpy(pskXtn.buf, &chInnerXtns.buf[chInnerXtns.len - pskXtn.len], pskXtn.len);
} else {
rv = sslBuffer_AppendBufferVariable(&chInner, &chInnerXtns, 2);
}
if (rv != SECSuccess) {
goto loser;
}
PRINT_BUF(50, (ss, "Uncompressed CHInner", chInner.buf, chInner.len));
rv = ssl3_UpdateHandshakeHashesInt(ss, chInner.buf, chInner.len,
&ss->ssl3.hs.echInnerMessages);
if (rv != SECSuccess) {
goto loser; /* code set */
}
/* Un-append the extensions, then append compressed via Encoded. */
SSL_BUFFER_LEN(&chInner) = preambleLen;
sslBuffer_Clear(&chInnerXtns);
rv = tls13_ConstructInnerExtensionsFromOuter(ss, chOuterXtnsBuf,
&chInnerXtns, &pskXtn, PR_TRUE);
if (rv != SECSuccess) {
goto loser;
}
rv = tls13_EncodeClientHelloInner(ss, &chInner, &chInnerXtns, &encodedChInner);
if (rv != SECSuccess) {
goto loser;
}
PRINT_BUF(50, (ss, "Compressed CHInner", encodedChInner.buf, encodedChInner.len));
PORT_Assert(!PR_CLIST_IS_EMPTY(&ss->echConfigs));
sslEchConfig *cfg = (sslEchConfig *)PR_LIST_HEAD(&ss->echConfigs);
/* We are using ECH so SNI must have been included */
rv = tls13_PadChInner(&encodedChInner, cfg->contents.maxNameLen, strlen(ss->url));
if (rv != SECSuccess) {
goto loser;
}
/* Build the ECH Xtn with placeholder and put it in chOuterXtnsBuf */
sslBuffer echXtn = SSL_BUFFER_EMPTY;
const SECItem *hpkeEnc = NULL;
if (!ss->ssl3.hs.helloRetry) {
hpkeEnc = PK11_HPKE_GetEncapPubKey(ss->ssl3.hs.echHpkeCtx);
if (!hpkeEnc) {
FATAL_ERROR(ss, SEC_ERROR_LIBRARY_FAILURE, internal_error);
goto loser;
}
}
PRUint16 echXtnPayloadOffset; /* Offset from start of ECH Xtn to ECH Payload */
rv = tls13_BuildEchXtn(cfg, hpkeEnc, encodedChInner.len, &echXtnPayloadOffset, &echXtn);
if (rv != SECSuccess) {
goto loser;
}
ss->xtnData.echAdvertised[ss->xtnData.echNumAdvertised++] = ssl_tls13_encrypted_client_hello_xtn;
rv = ssl3_EmplaceExtension(ss, chOuterXtnsBuf, ssl_tls13_encrypted_client_hello_xtn,
echXtn.buf, echXtn.len, PR_TRUE);
if (rv != SECSuccess) {
goto loser;
}
/* Add the padding */
rv = ssl_InsertPaddingExtension(ss, chOuter->len, chOuterXtnsBuf);
if (rv != SECSuccess) {
goto loser;
}
/* Finish the CHO with the ECH Xtn payload zeroed */
rv = ssl3_InsertChHeaderSize(ss, chOuter, chOuterXtnsBuf);
if (rv != SECSuccess) {
goto loser;
}
unsigned int chOuterXtnsOffset = chOuter->len + 2; /* From Start of CHO to Extensions list */
rv = sslBuffer_AppendBufferVariable(chOuter, chOuterXtnsBuf, 2);
if (rv != SECSuccess) {
goto loser;
}
/* AAD consists of entire CHO, minus the 4 byte handshake header */
SECItem aadItem = { siBuffer, chOuter->buf + 4, chOuter->len - 4 };
/* ECH Payload begins after CHO Header, after ECH Xtn start, after ECH Xtn header */
PRUint8 *echPayload = chOuter->buf + chOuterXtnsOffset + ss->xtnData.echXtnOffset + 4 + echXtnPayloadOffset;
/* Insert the encrypted_client_hello xtn and coalesce. */
rv = tls13_EncryptClientHello(ss, &aadItem, &encodedChInner, echPayload);
if (rv != SECSuccess) {
goto loser;
}
sslBuffer_Clear(&echXtn);
sslBuffer_Clear(&chInner);
sslBuffer_Clear(&encodedChInner);
sslBuffer_Clear(&paddingChInner);
sslBuffer_Clear(&chInnerXtns);
sslBuffer_Clear(&pskXtn);
return SECSuccess;
loser:
sslBuffer_Clear(&chInner);
sslBuffer_Clear(&encodedChInner);
sslBuffer_Clear(&paddingChInner);
sslBuffer_Clear(&chInnerXtns);
sslBuffer_Clear(&pskXtn);
PORT_Assert(PORT_GetError() != 0);
return SECFailure;
}
static SECStatus
tls13_ComputeEchHelloRetryTranscript(sslSocket *ss, const PRUint8 *sh, unsigned int shLen, sslBuffer *out)
{
SECStatus rv;
PRUint8 zeroedEchSignal[TLS13_ECH_SIGNAL_LEN] = { 0 };
sslBuffer *previousTranscript;
if (ss->sec.isServer) {
previousTranscript = &(ss->ssl3.hs.messages);
} else {
previousTranscript = &(ss->ssl3.hs.echInnerMessages);
}
/*
* This segment calculates the hash of the Client Hello
* TODO(djackson@mozilla.com) - Replace with existing function?
* e.g. tls13_ReinjectHandshakeTranscript
* TODO(djackson@mozilla.com) - Replace with streaming version
*/
if (!ss->ssl3.hs.helloRetry || !ss->sec.isServer) {
/*
* This function can be called in three situations:
* - By the server, prior to sending the HRR, when ECH was accepted
* - By the client, after receiving the HRR, but before it knows whether ECH was accepted
* - By the server, after accepting ECH and receiving CH2 when it needs to reconstruct the HRR
* In the first two situations, we need to include the message hash of inner ClientHello1 but don't
* want to alter the buffer containing the current transcript.
* In the last, the buffer already contains the message hash of inner ClientHello1.
*/
SSL3Hashes hashes;
rv = tls13_ComputeHash(ss, &hashes, previousTranscript->buf, previousTranscript->len, tls13_GetHash(ss));
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendNumber(out, ssl_hs_message_hash, 1);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendNumber(out, hashes.len, 3);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_Append(out, hashes.u.raw, hashes.len);
if (rv != SECSuccess) {
goto loser;
}
} else {
rv = sslBuffer_AppendBuffer(out, previousTranscript);
if (rv != SECSuccess) {
goto loser;
}
}
/* Ensure the first ClientHello has been hashed. */
PR_ASSERT(out->len == tls13_GetHashSize(ss) + 4);
PRINT_BUF(100, (ss, "ECH Client Hello Message Hash", out->buf, out->len));
/* Message Header */
rv = sslBuffer_AppendNumber(out, ssl_hs_server_hello, 1);
if (rv != SECSuccess) {
goto loser;
}
/* Message Size */
rv = sslBuffer_AppendNumber(out, shLen, 3);
if (rv != SECSuccess) {
goto loser;
}
/* Calculate where the HRR ECH Xtn Signal begins */
unsigned int absEchOffset;
if (ss->sec.isServer) {
/* We know the ECH HRR Xtn is last */
PORT_Assert(shLen >= TLS13_ECH_SIGNAL_LEN);
absEchOffset = shLen - TLS13_ECH_SIGNAL_LEN;
} else {
/* We parsed the offset earlier */
/* The result of pointer comparision is unspecified
* (and pointer arithemtic is undefined) if the pointers
* do not point to the same array or struct. That means these
* asserts cannot be relied on for correctness in compiled code,
* but may help the reader understand the requirements.
*/
PORT_Assert(ss->xtnData.ech->hrrConfirmation > sh);
PORT_Assert(ss->xtnData.ech->hrrConfirmation < sh + shLen);
absEchOffset = ss->xtnData.ech->hrrConfirmation - sh;
}
PR_ASSERT(tls13_Debug_CheckXtnBegins(sh + absEchOffset - 4, ssl_tls13_encrypted_client_hello_xtn));
/* The HRR up to the ECH Xtn signal */
rv = sslBuffer_Append(out, sh, absEchOffset);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_Append(out, zeroedEchSignal, sizeof(zeroedEchSignal));
if (rv != SECSuccess) {
goto loser;
}
PR_ASSERT(absEchOffset + TLS13_ECH_SIGNAL_LEN <= shLen);
/* The remainder of the HRR */
rv = sslBuffer_Append(out, sh + absEchOffset + TLS13_ECH_SIGNAL_LEN, shLen - absEchOffset - TLS13_ECH_SIGNAL_LEN);
if (rv != SECSuccess) {
goto loser;
}
PR_ASSERT(out->len == tls13_GetHashSize(ss) + 4 + shLen + 4);
return SECSuccess;
loser:
sslBuffer_Clear(out);
return SECFailure;
}
static SECStatus
tls13_ComputeEchServerHelloTranscript(sslSocket *ss, const PRUint8 *sh, unsigned int shLen, sslBuffer *out)
{
SECStatus rv;
sslBuffer *chSource = ss->sec.isServer ? &ss->ssl3.hs.messages : &ss->ssl3.hs.echInnerMessages;
unsigned int offset = sizeof(SSL3ProtocolVersion) +
SSL3_RANDOM_LENGTH - TLS13_ECH_SIGNAL_LEN;
PORT_Assert(sh && shLen > offset);
PORT_Assert(TLS13_ECH_SIGNAL_LEN <= SSL3_RANDOM_LENGTH);
/* TODO(djackson@mozilla.com) - Replace with streaming version */
rv = sslBuffer_AppendBuffer(out, chSource);
if (rv != SECSuccess) {
goto loser;
}
/* Re-create the message header. */
rv = sslBuffer_AppendNumber(out, ssl_hs_server_hello, 1);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendNumber(out, shLen, 3);
if (rv != SECSuccess) {
goto loser;
}
/* Copy the version and 24B of server_random. */
rv = sslBuffer_Append(out, sh, offset);
if (rv != SECSuccess) {
goto loser;
}
/* Zero the signal placeholder. */
rv = sslBuffer_AppendNumber(out, 0, TLS13_ECH_SIGNAL_LEN);
if (rv != SECSuccess) {
goto loser;
}
offset += TLS13_ECH_SIGNAL_LEN;
/* Use the remainder of SH. */
rv = sslBuffer_Append(out, &sh[offset], shLen - offset);
if (rv != SECSuccess) {
goto loser;
}
sslBuffer_Clear(&ss->ssl3.hs.messages);
sslBuffer_Clear(&ss->ssl3.hs.echInnerMessages);
return SECSuccess;
loser:
sslBuffer_Clear(&ss->ssl3.hs.messages);
sslBuffer_Clear(&ss->ssl3.hs.echInnerMessages);
sslBuffer_Clear(out);
return SECFailure;
}
/* Compute the ECH signal using the transcript (up to, including)
* ServerHello. The server sources this transcript prefix from
* ss->ssl3.hs.messages, as it never uses ss->ssl3.hs.echInnerMessages.
* The client uses the inner transcript, echInnerMessages. */
SECStatus
tls13_ComputeEchSignal(sslSocket *ss, PRBool isHrr, const PRUint8 *sh, unsigned int shLen, PRUint8 *out)
{
SECStatus rv;
sslBuffer confMsgs = SSL_BUFFER_EMPTY;
SSL3Hashes hashes;
PK11SymKey *echSecret = NULL;
const char *hkdfInfo = isHrr ? kHkdfInfoEchHrrConfirm : kHkdfInfoEchConfirm;
const size_t hkdfInfoLen = strlen(hkdfInfo);
PRINT_BUF(100, (ss, "ECH Server Hello", sh, shLen));
if (isHrr) {
rv = tls13_ComputeEchHelloRetryTranscript(ss, sh, shLen, &confMsgs);
} else {
rv = tls13_ComputeEchServerHelloTranscript(ss, sh, shLen, &confMsgs);
}
if (rv != SECSuccess) {
goto loser;
}
PRINT_BUF(100, (ss, "ECH Transcript", confMsgs.buf, confMsgs.len));
rv = tls13_ComputeHash(ss, &hashes, confMsgs.buf, confMsgs.len,
tls13_GetHash(ss));
if (rv != SECSuccess) {
goto loser;
}
PRINT_BUF(100, (ss, "ECH Transcript Hash", &hashes.u, hashes.len));
rv = tls13_DeriveEchSecret(ss, &echSecret);
if (rv != SECSuccess) {
return SECFailure;
}
rv = tls13_HkdfExpandLabelRaw(echSecret, tls13_GetHash(ss), hashes.u.raw,
hashes.len, hkdfInfo, hkdfInfoLen, ss->protocolVariant,
out, TLS13_ECH_SIGNAL_LEN);
if (rv != SECSuccess) {
return SECFailure;
}
SSL_TRC(50, ("%d: TLS13[%d]: %s computed ECH signal", SSL_GETPID(), ss->fd, SSL_ROLE(ss)));
PRINT_BUF(50, (ss, "Computed ECH Signal", out, TLS13_ECH_SIGNAL_LEN));
PK11_FreeSymKey(echSecret);
sslBuffer_Clear(&confMsgs);
return SECSuccess;
loser:
PK11_FreeSymKey(echSecret);
sslBuffer_Clear(&confMsgs);
return SECFailure;
}
/* Ech Secret is HKDF-Extract(0, ClientHelloInner.random) where
"0" is a string of Hash.len bytes of value 0. */
SECStatus
tls13_DeriveEchSecret(const sslSocket *ss, PK11SymKey **output)
{
SECStatus rv;
PK11SlotInfo *slot = NULL;
PK11SymKey *crKey = NULL;
SECItem rawKey;
const unsigned char *client_random = ss->sec.isServer ? ss->ssl3.hs.client_random : ss->ssl3.hs.client_inner_random;
PRINT_BUF(50, (ss, "Client Random for ECH", client_random, SSL3_RANDOM_LENGTH));
/* We need a SECItem */
rv = SECITEM_MakeItem(NULL, &rawKey, client_random, SSL3_RANDOM_LENGTH);
if (rv != SECSuccess) {
goto cleanup;
}
/* We need a slot*/
slot = PK11_GetBestSlot(CKM_HKDF_DERIVE, NULL);
if (!slot) {
rv = SECFailure;
goto cleanup;
}
/* We import the key */
crKey = PK11_ImportDataKey(slot, CKM_HKDF_DERIVE, PK11_OriginUnwrap,
CKA_DERIVE, &rawKey, NULL);
if (crKey == NULL) {
rv = SECFailure;
goto cleanup;
}
/* NULL will be expanded to 0s of hash length */
rv = tls13_HkdfExtract(NULL, crKey, tls13_GetHash(ss), output);
if (rv != SECSuccess) {
goto cleanup;
}
SSL_TRC(50, ("%d: TLS13[%d]: ECH Confirmation Key Derived.",
SSL_GETPID(), ss->fd));
PRINT_KEY(50, (NULL, "ECH Confirmation Key", *output));
cleanup:
SECITEM_ZfreeItem(&rawKey, PR_FALSE);
if (slot) {
PK11_FreeSlot(slot);
}
if (crKey) {
PK11_FreeSymKey(crKey);
}
if (rv != SECSuccess && *output) {
PK11_FreeSymKey(*output);
*output = NULL;
}
return rv;
}
/* Called just prior to padding the CH. Use the size of the CH to estimate
* the size of a corresponding ECH extension, then add it to the buffer. */
SECStatus
tls13_MaybeGreaseEch(sslSocket *ss, const sslBuffer *preamble, sslBuffer *buf)
{
SECStatus rv;
sslBuffer chInnerXtns = SSL_BUFFER_EMPTY;
sslBuffer encodedCh = SSL_BUFFER_EMPTY;
sslBuffer greaseBuf = SSL_BUFFER_EMPTY;
unsigned int payloadLen;
HpkeAeadId aead;
PK11SlotInfo *slot = NULL;
PK11SymKey *hmacPrk = NULL;
PK11SymKey *derivedData = NULL;
SECItem *rawData;
CK_HKDF_PARAMS params;
SECItem paramsi;
/* 1B aead determinant (don't send), 1B config_id, 32B enc, payload */
PR_ASSERT(!ss->sec.isServer);
const int kNonPayloadLen = 34;
if (!ss->opt.enableTls13GreaseEch || ss->ssl3.hs.echHpkeCtx) {
return SECSuccess;
}
if (ss->vrange.max < SSL_LIBRARY_VERSION_TLS_1_3 ||
IS_DTLS(ss)) {
return SECSuccess;
}
/* In draft-09, CH2 sends exactly the same GREASE ECH extension. */
if (ss->ssl3.hs.helloRetry) {
return ssl3_EmplaceExtension(ss, buf, ssl_tls13_encrypted_client_hello_xtn,
ss->ssl3.hs.greaseEchBuf.buf,
ss->ssl3.hs.greaseEchBuf.len, PR_TRUE);
}
/* Compress the extensions for payload length. */
rv = tls13_ConstructInnerExtensionsFromOuter(ss, buf, &chInnerXtns,
NULL, PR_TRUE);
if (rv != SECSuccess) {
goto loser; /* Code set */
}
rv = tls13_EncodeClientHelloInner(ss, preamble, &chInnerXtns, &encodedCh);
if (rv != SECSuccess) {
goto loser; /* Code set */
}
rv = tls13_PadChInner(&encodedCh, ss->ssl3.hs.greaseEchSize, strlen(ss->url));
payloadLen = encodedCh.len;
payloadLen += TLS13_ECH_AEAD_TAG_LEN; /* Aead tag */
/* HMAC-Expand to get something that will pass for ciphertext. */
slot = PK11_GetBestSlot(CKM_HKDF_DERIVE, NULL);
if (!slot) {
goto loser;
}
hmacPrk = PK11_KeyGen(slot, CKM_HKDF_DATA, NULL, SHA256_LENGTH, NULL);
if (!hmacPrk) {
goto loser;
}
params.bExtract = CK_FALSE;
params.bExpand = CK_TRUE;
params.prfHashMechanism = CKM_SHA256;
params.pInfo = NULL;
params.ulInfoLen = 0;
paramsi.data = (unsigned char *)&params;
paramsi.len = sizeof(params);
derivedData = PK11_DeriveWithFlags(hmacPrk, CKM_HKDF_DATA,
&paramsi, CKM_HKDF_DATA,
CKA_DERIVE, kNonPayloadLen + payloadLen,
CKF_VERIFY);
if (!derivedData) {
goto loser;
}
rv = PK11_ExtractKeyValue(derivedData);
if (rv != SECSuccess) {
goto loser;
}
rawData = PK11_GetKeyData(derivedData);
if (!rawData) {
goto loser;
}
PORT_Assert(rawData->len == kNonPayloadLen + payloadLen);
/* struct {
HpkeSymmetricCipherSuite cipher_suite; // kdf_id, aead_id
PRUint8 config_id;
opaque enc<1..2^16-1>;
opaque payload<1..2^16-1>;
} ClientECH; */
rv = sslBuffer_AppendNumber(&greaseBuf, ech_xtn_type_outer, 1);
if (rv != SECSuccess) {
goto loser;
}
/* Only support SHA256. */
rv = sslBuffer_AppendNumber(&greaseBuf, HpkeKdfHkdfSha256, 2);
if (rv != SECSuccess) {
goto loser;
}
/* HpkeAeadAes128Gcm = 1, HpkeAeadChaCha20Poly1305 = 3, */
aead = (rawData->data[0] & 1) ? HpkeAeadAes128Gcm : HpkeAeadChaCha20Poly1305;
rv = sslBuffer_AppendNumber(&greaseBuf, aead, 2);
if (rv != SECSuccess) {
goto loser;
}
/* config_id */
rv = sslBuffer_AppendNumber(&greaseBuf, rawData->data[1], 1);
if (rv != SECSuccess) {
goto loser;
}
/* enc len is fixed 32B for X25519. */
rv = sslBuffer_AppendVariable(&greaseBuf, &rawData->data[2], 32, 2);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendVariable(&greaseBuf, &rawData->data[kNonPayloadLen], payloadLen, 2);
if (rv != SECSuccess) {
goto loser;
}
/* Mark ECH as advertised so that we can validate any response.
* We'll use echHpkeCtx to determine if we sent real or GREASE ECH. */
rv = ssl3_EmplaceExtension(ss, buf, ssl_tls13_encrypted_client_hello_xtn,
greaseBuf.buf, greaseBuf.len, PR_TRUE);
if (rv != SECSuccess) {
goto loser;
}
/* Stash the GREASE ECH extension - in the case of HRR, CH2 must echo it. */
ss->ssl3.hs.greaseEchBuf = greaseBuf;
sslBuffer_Clear(&chInnerXtns);
sslBuffer_Clear(&encodedCh);
PK11_FreeSymKey(hmacPrk);
PK11_FreeSymKey(derivedData);
PK11_FreeSlot(slot);
return SECSuccess;
loser:
sslBuffer_Clear(&chInnerXtns);
sslBuffer_Clear(&encodedCh);
PK11_FreeSymKey(hmacPrk);
PK11_FreeSymKey(derivedData);
if (slot) {
PK11_FreeSlot(slot);
}
return SECFailure;
}
SECStatus
tls13_MaybeHandleEch(sslSocket *ss, const PRUint8 *msg, PRUint32 msgLen, SECItem *sidBytes,
SECItem *comps, SECItem *cookieBytes, SECItem *suites, SECItem **echInner)
{
SECStatus rv;
SECItem *tmpEchInner = NULL;
PRUint8 *b;
PRUint32 length;
TLSExtension *echExtension;
TLSExtension *versionExtension;
PORT_Assert(!ss->ssl3.hs.echAccepted);
SECItem tmpSid = { siBuffer, NULL, 0 };
SECItem tmpCookie = { siBuffer, NULL, 0 };
SECItem tmpSuites = { siBuffer, NULL, 0 };
SECItem tmpComps = { siBuffer, NULL, 0 };
echExtension = ssl3_FindExtension(ss, ssl_tls13_encrypted_client_hello_xtn);
if (echExtension) {
rv = tls13_ServerHandleOuterEchXtn(ss, &ss->xtnData, &echExtension->data);
if (rv != SECSuccess) {
goto loser; /* code set, alert sent. */
}
rv = tls13_MaybeAcceptEch(ss, sidBytes, msg, msgLen, &tmpEchInner);
if (rv != SECSuccess) {
goto loser; /* code set, alert sent. */
}
}
ss->ssl3.hs.preliminaryInfo |= ssl_preinfo_ech;
if (ss->ssl3.hs.echAccepted) {
PORT_Assert(tmpEchInner);
PORT_Assert(!PR_CLIST_IS_EMPTY(&ss->ssl3.hs.remoteExtensions));
/* Start over on ECHInner */
b = tmpEchInner->data;
length = tmpEchInner->len;
rv = ssl3_HandleClientHelloPreamble(ss, &b, &length, &tmpSid,
&tmpCookie, &tmpSuites, &tmpComps);
if (rv != SECSuccess) {
goto loser; /* code set, alert sent. */
}
versionExtension = ssl3_FindExtension(ss, ssl_tls13_supported_versions_xtn);
if (!versionExtension) {
FATAL_ERROR(ss, SSL_ERROR_UNSUPPORTED_VERSION, illegal_parameter);
goto loser;
}
rv = tls13_NegotiateVersion(ss, versionExtension);
if (rv != SECSuccess) {
/* code and alert set by tls13_NegotiateVersion */
goto loser;
}
*comps = tmpComps;
*cookieBytes = tmpCookie;
*sidBytes = tmpSid;
*suites = tmpSuites;
*echInner = tmpEchInner;
}
return SECSuccess;
loser:
SECITEM_FreeItem(tmpEchInner, PR_TRUE);
PORT_Assert(PORT_GetError() != 0);
return SECFailure;
}
SECStatus
tls13_MaybeHandleEchSignal(sslSocket *ss, const PRUint8 *sh, PRUint32 shLen, PRBool isHrr)
{
SECStatus rv;
PRUint8 computed[TLS13_ECH_SIGNAL_LEN];
const PRUint8 *signal;
PORT_Assert(!ss->sec.isServer);
/* If !echHpkeCtx, we either didn't advertise or sent GREASE ECH. */
if (!ss->ssl3.hs.echHpkeCtx) {
SSL_TRC(50, ("%d: TLS13[%d]: client only sent GREASE ECH",
SSL_GETPID(), ss->fd));
ss->ssl3.hs.preliminaryInfo |= ssl_preinfo_ech;
return SECSuccess;
}
PORT_Assert(!IS_DTLS(ss));
if (isHrr) {
if (ss->xtnData.ech) {
signal = ss->xtnData.ech->hrrConfirmation;
} else {
SSL_TRC(50, ("%d: TLS13[%d]: client did not receive ECH Xtn from Server HRR",
SSL_GETPID(), ss->fd));
signal = NULL;
ss->ssl3.hs.echAccepted = PR_FALSE;
ss->ssl3.hs.echDecided = PR_TRUE;
}
} else {
signal = &ss->ssl3.hs.server_random[SSL3_RANDOM_LENGTH - TLS13_ECH_SIGNAL_LEN];
}
PORT_Assert(ssl3_ExtensionAdvertised(ss, ssl_tls13_encrypted_client_hello_xtn));
/* Check ECH Confirmation for HRR ECH Xtn or ServerHello Random */
if (signal) {
rv = tls13_ComputeEchSignal(ss, isHrr, sh, shLen, computed);
if (rv != SECSuccess) {
return SECFailure;
}
PRINT_BUF(100, (ss, "Server Signal", signal, TLS13_ECH_SIGNAL_LEN));
PRBool new_decision = !NSS_SecureMemcmp(computed, signal, TLS13_ECH_SIGNAL_LEN);
/* Server can't change its mind on whether to accept ECH */
if (ss->ssl3.hs.echDecided && new_decision != ss->ssl3.hs.echAccepted) {
FATAL_ERROR(ss, SSL_ERROR_RX_MALFORMED_SERVER_HELLO, illegal_parameter);
return SECFailure;
}
ss->ssl3.hs.echAccepted = new_decision;
ss->ssl3.hs.echDecided = PR_TRUE;
}
ss->ssl3.hs.preliminaryInfo |= ssl_preinfo_ech;
if (ss->ssl3.hs.echAccepted) {
if (ss->version < SSL_LIBRARY_VERSION_TLS_1_3) {
FATAL_ERROR(ss, SSL_ERROR_RX_MALFORMED_SERVER_HELLO, illegal_parameter);
return SECFailure;
}
/* Server accepted, but sent an extension which was only advertised in the ClientHelloOuter */
if (ss->ssl3.hs.echInvalidExtension) {
(void)SSL3_SendAlert(ss, alert_fatal, unsupported_extension);
PORT_SetError(SSL_ERROR_RX_UNEXPECTED_EXTENSION);
return SECFailure;
}
/* Swap the advertised lists as we've accepted ECH. */
PRUint16 *tempArray = ss->xtnData.advertised;
PRUint16 tempNum = ss->xtnData.numAdvertised;
ss->xtnData.advertised = ss->xtnData.echAdvertised;
ss->xtnData.numAdvertised = ss->xtnData.echNumAdvertised;
ss->xtnData.echAdvertised = tempArray;
ss->xtnData.echNumAdvertised = tempNum;
/* |enc| must not be included in CH2.ClientECH. */
if (ss->ssl3.hs.helloRetry && ss->sec.isServer &&
ss->xtnData.ech->senderPubKey.len) {
ssl3_ExtSendAlert(ss, alert_fatal, illegal_parameter);
PORT_SetError(SSL_ERROR_BAD_2ND_CLIENT_HELLO);
return SECFailure;
}
ss->xtnData.negotiated[ss->xtnData.numNegotiated++] = ssl_tls13_encrypted_client_hello_xtn;
/* Only overwrite client_random with client_inner_random if CHInner was
* succesfully used for handshake (NOT if HRR is received). */
if (!isHrr) {
PORT_Memcpy(ss->ssl3.hs.client_random, ss->ssl3.hs.client_inner_random, SSL3_RANDOM_LENGTH);
}
}
/* If rejected, leave echHpkeCtx and echPublicName for rejection paths. */
ssl3_CoalesceEchHandshakeHashes(ss);
SSL_TRC(3, ("%d: TLS13[%d]: ECH %s accepted by server",
SSL_GETPID(), ss->fd, ss->ssl3.hs.echAccepted ? "is" : "is not"));
return SECSuccess;
}
static SECStatus
tls13_UnencodeChInner(sslSocket *ss, const SECItem *sidBytes, SECItem **echInner)
{
SECStatus rv;
sslReadBuffer outerExtensionsList;
sslReadBuffer tmpReadBuf;
sslBuffer unencodedChInner = SSL_BUFFER_EMPTY;
PRCList *outerCursor;
PRCList *innerCursor;
PRBool outerFound;
PRUint32 xtnsOffset;
PRUint64 tmp;
PRUint8 *tmpB;
PRUint32 tmpLength;
sslReader chReader = SSL_READER((*echInner)->data, (*echInner)->len);
PORT_Assert(!PR_CLIST_IS_EMPTY(&ss->ssl3.hs.echOuterExtensions));
PORT_Assert(PR_CLIST_IS_EMPTY(&ss->ssl3.hs.remoteExtensions));
TLSExtension *echExtension;
int error = SSL_ERROR_INTERNAL_ERROR_ALERT;
int errDesc = internal_error;
PRINT_BUF(100, (ss, "ECH Inner", chReader.buf.buf, chReader.buf.len));
/* unencodedChInner := preamble, tmpReadBuf := encoded extensions. */
rv = tls13_CopyChPreamble(ss, &chReader, sidBytes, &unencodedChInner, &tmpReadBuf);
if (rv != SECSuccess) {
goto loser; /* code set */
}
/* Parse inner extensions into ss->ssl3.hs.remoteExtensions. */
tmpB = CONST_CAST(PRUint8, tmpReadBuf.buf);
rv = ssl3_ParseExtensions(ss, &tmpB, &tmpReadBuf.len);
if (rv != SECSuccess) {
goto loser; /* malformed, alert sent. */
}
echExtension = ssl3_FindExtension(ss, ssl_tls13_encrypted_client_hello_xtn);
if (!echExtension) {
error = SSL_ERROR_MISSING_ECH_EXTENSION;
errDesc = illegal_parameter;
goto alert_loser; /* Must have an inner Extension */
}
rv = tls13_ServerHandleInnerEchXtn(ss, &ss->xtnData, &echExtension->data);
if (rv != SECSuccess) {
goto loser; /* code set, alert sent. */
}
/* Exit early if there are no outer_extensions to decompress. */
if (!ssl3_FindExtension(ss, ssl_tls13_outer_extensions_xtn)) {
rv = sslBuffer_AppendVariable(&unencodedChInner, tmpReadBuf.buf, tmpReadBuf.len, 2);
if (rv != SECSuccess) {
goto loser;
}
sslBuffer_Clear(&unencodedChInner);
return SECSuccess;
}
/* Save room for uncompressed length. */
rv = sslBuffer_Skip(&unencodedChInner, 2, &xtnsOffset);
if (rv != SECSuccess) {
goto loser;
}
/* For each inner extension: If not outer_extensions, copy it to the output.
* Else if outer_extensions, iterate the compressed extension list and append
* each full extension as contained in CHOuter. Compressed extensions must be
* contiguous, so decompress at the point at which outer_extensions appears. */
for (innerCursor = PR_NEXT_LINK(&ss->ssl3.hs.remoteExtensions);
innerCursor != &ss->ssl3.hs.remoteExtensions;
innerCursor = PR_NEXT_LINK(innerCursor)) {
TLSExtension *innerExtension = (TLSExtension *)innerCursor;
if (innerExtension->type != ssl_tls13_outer_extensions_xtn) {
SSL_TRC(10, ("%d: SSL3[%d]: copying inner extension of type %d and size %d directly", SSL_GETPID(),
ss->fd, innerExtension->type, innerExtension->data.len));
rv = sslBuffer_AppendNumber(&unencodedChInner,
innerExtension->type, 2);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendVariable(&unencodedChInner,
innerExtension->data.data,
innerExtension->data.len, 2);
if (rv != SECSuccess) {
goto loser;
}
continue;
}
/* Decompress */
sslReader extensionRdr = SSL_READER(innerExtension->data.data,
innerExtension->data.len);
rv = sslRead_ReadVariable(&extensionRdr, 1, &outerExtensionsList);
if (rv != SECSuccess) {
SSL_TRC(10, ("%d: SSL3[%d]: ECH Outer Extensions has invalid size.",
SSL_GETPID(), ss->fd));
error = SSL_ERROR_RX_MALFORMED_ECH_EXTENSION;
errDesc = illegal_parameter;
goto alert_loser;
}
if (SSL_READER_REMAINING(&extensionRdr) || (outerExtensionsList.len % 2) != 0 || !outerExtensionsList.len) {
SSL_TRC(10, ("%d: SSL3[%d]: ECH Outer Extensions has invalid size.",
SSL_GETPID(), ss->fd));
error = SSL_ERROR_RX_MALFORMED_ECH_EXTENSION;
errDesc = illegal_parameter;
goto alert_loser;
}
outerCursor = &ss->ssl3.hs.echOuterExtensions;
sslReader compressedTypes = SSL_READER(outerExtensionsList.buf, outerExtensionsList.len);
while (SSL_READER_REMAINING(&compressedTypes)) {
outerFound = PR_FALSE;
rv = sslRead_ReadNumber(&compressedTypes, 2, &tmp);
if (rv != SECSuccess) {
SSL_TRC(10, ("%d: SSL3[%d]: ECH Outer Extensions has invalid contents.",
SSL_GETPID(), ss->fd));
error = SSL_ERROR_RX_MALFORMED_ECH_EXTENSION;
errDesc = illegal_parameter;
goto alert_loser;
}
if (tmp == ssl_tls13_encrypted_client_hello_xtn ||
tmp == ssl_tls13_outer_extensions_xtn) {
SSL_TRC(10, ("%d: SSL3[%d]: ECH Outer Extensions contains an invalid reference.",
SSL_GETPID(), ss->fd));
error = SSL_ERROR_RX_MALFORMED_ECH_EXTENSION;
errDesc = illegal_parameter;
goto alert_loser;
}
do {
const TLSExtension *candidate = (TLSExtension *)outerCursor;
/* Advance the outerCursor, we never consider the same xtn twice. */
outerCursor = PR_NEXT_LINK(outerCursor);
if (candidate->type == tmp) {
outerFound = PR_TRUE;
SSL_TRC(100, ("%d: SSL3[%d]: Decompressing ECH Inner Extension of type %d",
SSL_GETPID(), ss->fd, tmp));
rv = sslBuffer_AppendNumber(&unencodedChInner,
candidate->type, 2);
if (rv != SECSuccess) {
goto loser;
}
rv = sslBuffer_AppendVariable(&unencodedChInner,
candidate->data.data,
candidate->data.len, 2);
if (rv != SECSuccess) {
goto loser;
}
break;
}
} while (outerCursor != &ss->ssl3.hs.echOuterExtensions);
if (!outerFound) {
SSL_TRC(10, ("%d: SSL3[%d]: ECH Outer Extensions has missing,"
" out of order or duplicate references.",
SSL_GETPID(), ss->fd));
error = SSL_ERROR_RX_MALFORMED_ECH_EXTENSION;
errDesc = illegal_parameter;
goto alert_loser;
}
}
}
ssl3_DestroyRemoteExtensions(&ss->ssl3.hs.echOuterExtensions);
ssl3_DestroyRemoteExtensions(&ss->ssl3.hs.remoteExtensions);
/* Correct the message and extensions sizes. */
rv = sslBuffer_InsertNumber(&unencodedChInner, xtnsOffset,
unencodedChInner.len - xtnsOffset - 2, 2);
if (rv != SECSuccess) {
goto loser;
}
tmpB = &unencodedChInner.buf[xtnsOffset];
tmpLength = unencodedChInner.len - xtnsOffset;
rv = ssl3_ConsumeHandshakeNumber64(ss, &tmp, 2, &tmpB, &tmpLength);
if (rv != SECSuccess || tmpLength != tmp) {
error = SSL_ERROR_RX_MALFORMED_CLIENT_HELLO;
errDesc = internal_error;
goto alert_loser;
}
rv = ssl3_ParseExtensions(ss, &tmpB, &tmpLength);
if (rv != SECSuccess) {
goto loser; /* Error set and alert already sent */
}
SECITEM_FreeItem(*echInner, PR_FALSE);
(*echInner)->data = unencodedChInner.buf;
(*echInner)->len = unencodedChInner.len;
return SECSuccess;
alert_loser:
FATAL_ERROR(ss, error, errDesc);
loser:
sslBuffer_Clear(&unencodedChInner);
return SECFailure;
}
SECStatus
tls13_MaybeAcceptEch(sslSocket *ss, const SECItem *sidBytes, const PRUint8 *chOuter,
unsigned int chOuterLen, SECItem **chInner)
{
SECStatus rv;
SECItem outer = { siBuffer, CONST_CAST(PRUint8, chOuter), chOuterLen };
SECItem *decryptedChInner = NULL;
SECItem outerAAD = { siBuffer, NULL, 0 };
SECItem cookieData = { siBuffer, NULL, 0 };
sslEchCookieData echData;
sslEchConfig *candidate = NULL; /* non-owning */
TLSExtension *hrrXtn;
PRBool previouslyOfferedEch;
if (!ss->xtnData.ech || ss->xtnData.ech->receivedInnerXtn || IS_DTLS(ss)) {
ss->ssl3.hs.echDecided = PR_TRUE;
return SECSuccess;
}
PORT_Assert(ss->xtnData.ech->innerCh.data);
if (ss->ssl3.hs.helloRetry) {
ss->ssl3.hs.echDecided = PR_TRUE;
PORT_Assert(!ss->ssl3.hs.echHpkeCtx);
hrrXtn = ssl3_FindExtension(ss, ssl_tls13_cookie_xtn);
if (!hrrXtn) {
/* If the client doesn't echo cookie, we can't decrypt. */
return SECSuccess;
}
PORT_Assert(!ss->ssl3.hs.echHpkeCtx);
PRUint8 *tmp = hrrXtn->data.data;
PRUint32 len = hrrXtn->data.len;
rv = ssl3_ExtConsumeHandshakeVariable(ss, &cookieData, 2,
&tmp, &len);
if (rv != SECSuccess) {
return SECFailure;
}
/* Extract ECH info without restoring hash state. If there's
* something wrong with the cookie, continue without ECH
* and let HRR code handle the problem. */
rv = tls13_HandleHrrCookie(ss, cookieData.data, cookieData.len,
NULL, NULL, &previouslyOfferedEch, &echData, PR_FALSE);
if (rv != SECSuccess) {
return SECSuccess;
}
ss->ssl3.hs.echHpkeCtx = echData.hpkeCtx;
const PRUint8 greaseConstant[TLS13_ECH_SIGNAL_LEN] = { 0 };
ss->ssl3.hs.echAccepted = previouslyOfferedEch &&
!NSS_SecureMemcmp(greaseConstant, echData.signal, TLS13_ECH_SIGNAL_LEN);
if (echData.configId != ss->xtnData.ech->configId ||
echData.kdfId != ss->xtnData.ech->kdfId ||
echData.aeadId != ss->xtnData.ech->aeadId) {
FATAL_ERROR(ss, SSL_ERROR_BAD_2ND_CLIENT_HELLO,
illegal_parameter);
return SECFailure;
}
if (!ss->ssl3.hs.echHpkeCtx) {
return SECSuccess;
}
}
if (ss->ssl3.hs.echDecided && !ss->ssl3.hs.echAccepted) {
/* We don't change our mind */
return SECSuccess;
}
/* Regardless of where we return, the outcome is decided */
ss->ssl3.hs.echDecided = PR_TRUE;
/* Cookie data was good, proceed with ECH. */
rv = tls13_GetMatchingEchConfigs(ss, ss->xtnData.ech->kdfId, ss->xtnData.ech->aeadId,
ss->xtnData.ech->configId, candidate, &candidate);
if (rv != SECSuccess) {
FATAL_ERROR(ss, SEC_ERROR_LIBRARY_FAILURE, internal_error);
return SECFailure;
}
if (candidate) {
rv = tls13_ServerMakeChOuterAAD(ss, chOuter, chOuterLen, &outerAAD);
if (rv != SECSuccess) {
return SECFailure;
}
}
while (candidate) {
rv = tls13_OpenClientHelloInner(ss, &outer, &outerAAD, candidate, &decryptedChInner);
if (rv != SECSuccess) {
/* Get the next matching config */
rv = tls13_GetMatchingEchConfigs(ss, ss->xtnData.ech->kdfId, ss->xtnData.ech->aeadId,
ss->xtnData.ech->configId, candidate, &candidate);
if (rv != SECSuccess) {
FATAL_ERROR(ss, SEC_ERROR_LIBRARY_FAILURE, internal_error);
SECITEM_FreeItem(&outerAAD, PR_FALSE);
return SECFailure;
}
continue;
}
break;
}
SECITEM_FreeItem(&outerAAD, PR_FALSE);
if (rv != SECSuccess || !decryptedChInner) {
if (ss->ssl3.hs.helloRetry) {
FATAL_ERROR(ss, SSL_ERROR_RX_MALFORMED_ECH_EXTENSION, decrypt_error);
return SECFailure;
} else {
/* Send retry_configs (if we have any) when we fail to decrypt or
* found no candidates. This does *not* count as negotiating ECH. */
return ssl3_RegisterExtensionSender(ss, &ss->xtnData,
ssl_tls13_encrypted_client_hello_xtn,
tls13_ServerSendEchXtn);
}
}
SSL_TRC(20, ("%d: TLS13[%d]: Successfully opened ECH inner CH",
SSL_GETPID(), ss->fd));
PRINT_BUF(50, (ss, "Compressed CHInner", decryptedChInner->data,
decryptedChInner->len));
ss->ssl3.hs.echAccepted = PR_TRUE;
/* Stash the CHOuter extensions. They're not yet handled (only parsed). If
* the CHInner contains outer_extensions_xtn, we'll need to reference them. */
ssl3_MoveRemoteExtensions(&ss->ssl3.hs.echOuterExtensions, &ss->ssl3.hs.remoteExtensions);
rv = tls13_UnencodeChInner(ss, sidBytes, &decryptedChInner);
if (rv != SECSuccess) {
SECITEM_FreeItem(decryptedChInner, PR_TRUE);
return SECFailure; /* code set */
}
PRINT_BUF(50, (ss, "Uncompressed CHInner", decryptedChInner->data,
decryptedChInner->len));
*chInner = decryptedChInner;
return SECSuccess;
}
SECStatus
tls13_WriteServerEchSignal(sslSocket *ss, PRUint8 *sh, unsigned int shLen)
{
SECStatus rv;
PRUint8 signal[TLS13_ECH_SIGNAL_LEN];
PRUint8 *msg_random = &sh[sizeof(SSL3ProtocolVersion)];
PORT_Assert(shLen > sizeof(SSL3ProtocolVersion) + SSL3_RANDOM_LENGTH);
PORT_Assert(ss->version >= SSL_LIBRARY_VERSION_TLS_1_3);
rv = tls13_ComputeEchSignal(ss, PR_FALSE, sh, shLen, signal);
if (rv != SECSuccess) {
return SECFailure;
}
PRUint8 *dest = &msg_random[SSL3_RANDOM_LENGTH - TLS13_ECH_SIGNAL_LEN];
PORT_Memcpy(dest, signal, TLS13_ECH_SIGNAL_LEN);
/* Keep the socket copy consistent. */
PORT_Assert(0 == memcmp(msg_random, &ss->ssl3.hs.server_random, SSL3_RANDOM_LENGTH - TLS13_ECH_SIGNAL_LEN));
dest = &ss->ssl3.hs.server_random[SSL3_RANDOM_LENGTH - TLS13_ECH_SIGNAL_LEN];
PORT_Memcpy(dest, signal, TLS13_ECH_SIGNAL_LEN);
return SECSuccess;
}
SECStatus
tls13_WriteServerEchHrrSignal(sslSocket *ss, PRUint8 *sh, unsigned int shLen)
{
SECStatus rv;
PR_ASSERT(shLen >= 4 + TLS13_ECH_SIGNAL_LEN);
/* We put the HRR ECH extension last. */
PRUint8 *placeholder_location = sh + shLen - TLS13_ECH_SIGNAL_LEN;
/* Defensive check that we are overwriting the contents of the right extension */
PR_ASSERT(tls13_Debug_CheckXtnBegins(placeholder_location - 4, ssl_tls13_encrypted_client_hello_xtn));
/* Calculate signal and overwrite */
rv = tls13_ComputeEchSignal(ss, PR_TRUE, sh, shLen, placeholder_location);
if (rv != SECSuccess) {
return SECFailure;
}
/* Free HRR GREASE/accept_confirmation value, it MUST be restored from
* cookie when handling CH2 after HRR. */
sslBuffer_Clear(&ss->ssl3.hs.greaseEchBuf);
return SECSuccess;
}