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/* SPDX-License-Identifier: GPL-2.0
*
* Copyright (C) 2015-2021 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
#include "cookie.h"
#include "peer.h"
#include "device.h"
#include "messages.h"
#include "ratelimiter.h"
#include "timers.h"
#include "crypto.h"
#include "queueing.h"
#include "logging.h"
#pragma warning(disable : 4295) /* array is too small to include a terminating null character */
_Use_decl_annotations_
VOID
CookieCheckerInit(COOKIE_CHECKER *Checker, WG_DEVICE *Wg)
{
MuInitializePushLock(&Checker->SecretLock);
Checker->SecretBirthdate = KeQueryInterruptTime();
CryptoRandom(Checker->Secret, NOISE_HASH_LEN);
Checker->Device = Wg;
}
enum
{
COOKIE_KEY_LABEL_LEN = 8
};
static CONST UINT8 Mac1KeyLabel[COOKIE_KEY_LABEL_LEN] = "mac1----";
static CONST UINT8 CookieKeyLabel[COOKIE_KEY_LABEL_LEN] = "cookie--";
static VOID
PrecomputeKey(
_Out_writes_bytes_all_(NOISE_SYMMETRIC_KEY_LEN) UINT8 Key[NOISE_SYMMETRIC_KEY_LEN],
_In_reads_bytes_(NOISE_PUBLIC_KEY_LEN) CONST UINT8 Pubkey[NOISE_PUBLIC_KEY_LEN],
_In_reads_bytes_(COOKIE_KEY_LABEL_LEN) CONST UINT8 Label[COOKIE_KEY_LABEL_LEN])
{
BLAKE2S_STATE Blake;
Blake2sInit(&Blake, NOISE_SYMMETRIC_KEY_LEN);
Blake2sUpdate(&Blake, Label, COOKIE_KEY_LABEL_LEN);
Blake2sUpdate(&Blake, Pubkey, NOISE_PUBLIC_KEY_LEN);
Blake2sFinal(&Blake, Key);
}
_Use_decl_annotations_
VOID
CookieCheckerPrecomputeDeviceKeys(COOKIE_CHECKER *Checker)
{
if (Checker->Device->StaticIdentity.HasIdentity)
{
PrecomputeKey(Checker->CookieEncryptionKey, Checker->Device->StaticIdentity.StaticPublic, CookieKeyLabel);
PrecomputeKey(Checker->MessageMac1Key, Checker->Device->StaticIdentity.StaticPublic, Mac1KeyLabel);
}
else
{
RtlZeroMemory(Checker->CookieEncryptionKey, NOISE_SYMMETRIC_KEY_LEN);
RtlZeroMemory(Checker->MessageMac1Key, NOISE_SYMMETRIC_KEY_LEN);
}
}
_Use_decl_annotations_
VOID
CookieCheckerPrecomputePeerKeys(WG_PEER *Peer)
{
PrecomputeKey(Peer->LatestCookie.CookieDecryptionKey, Peer->Handshake.RemoteStatic, CookieKeyLabel);
PrecomputeKey(Peer->LatestCookie.MessageMac1Key, Peer->Handshake.RemoteStatic, Mac1KeyLabel);
}
_Use_decl_annotations_
VOID
CookieInit(COOKIE *Cookie)
{
RtlZeroMemory(Cookie, sizeof(*Cookie));
MuInitializePushLock(&Cookie->Lock);
}
static VOID
ComputeMac1(
_Out_writes_bytes_all_(COOKIE_LEN) UINT8 Mac1[COOKIE_LEN],
_In_reads_bytes_(Len - sizeof(MESSAGE_MACS)) CONST VOID *Message,
_In_ SIZE_T Len,
_In_ CONST UINT8 Key[NOISE_SYMMETRIC_KEY_LEN])
{
Len = Len - sizeof(MESSAGE_MACS) + FIELD_OFFSET(MESSAGE_MACS, Mac1);
Blake2s(Mac1, Message, Key, COOKIE_LEN, Len, NOISE_SYMMETRIC_KEY_LEN);
}
static VOID
ComputeMac2(
_Out_writes_bytes_all_(COOKIE_LEN) UINT8 Mac2[COOKIE_LEN],
_In_reads_bytes_(Len - COOKIE_LEN) CONST VOID *Message,
_In_ SIZE_T Len,
_In_ CONST UINT8 Cookie[COOKIE_LEN])
{
Len = Len - sizeof(MESSAGE_MACS) + FIELD_OFFSET(MESSAGE_MACS, Mac2);
Blake2s(Mac2, Message, Cookie, COOKIE_LEN, Len, COOKIE_LEN);
}
_Requires_lock_not_held_(Checker->SecretLock)
_IRQL_requires_max_(APC_LEVEL)
static VOID
MakeCookie(
_Out_writes_bytes_all_(COOKIE_LEN) UINT8 Cookie[COOKIE_LEN],
_In_ CONST SOCKADDR *Src,
_Inout_ COOKIE_CHECKER *Checker)
{
BLAKE2S_STATE State;
if (BirthdateHasExpired(Checker->SecretBirthdate, COOKIE_SECRET_MAX_AGE))
{
MuAcquirePushLockExclusive(&Checker->SecretLock);
Checker->SecretBirthdate = KeQueryInterruptTime();
CryptoRandom(Checker->Secret, NOISE_HASH_LEN);
MuReleasePushLockExclusive(&Checker->SecretLock);
}
MuAcquirePushLockShared(&Checker->SecretLock);
Blake2sInitKey(&State, COOKIE_LEN, Checker->Secret, NOISE_HASH_LEN);
if (Src->sa_family == AF_INET)
{
CONST SOCKADDR_IN *Src4 = (CONST SOCKADDR_IN *)Src;
Blake2sUpdate(&State, (UINT8 *)&Src4->sin_addr, sizeof(Src4->sin_addr));
Blake2sUpdate(&State, (UINT8 *)&Src4->sin_port, sizeof(Src4->sin_port));
}
else if (Src->sa_family == AF_INET6)
{
CONST SOCKADDR_IN6 *Src6 = (CONST SOCKADDR_IN6 *)Src;
Blake2sUpdate(&State, (UINT8 *)&Src6->sin6_addr, sizeof(Src6->sin6_addr));
Blake2sUpdate(&State, (UINT8 *)&Src6->sin6_port, sizeof(Src6->sin6_port));
}
Blake2sFinal(&State, Cookie);
MuReleasePushLockShared(&Checker->SecretLock);
}
_Use_decl_annotations_
COOKIE_MAC_STATE
CookieValidatePacket(COOKIE_CHECKER *Checker, NET_BUFFER_LIST *Nbl, BOOLEAN CheckCookie)
{
CONST ULONG NblLen = NET_BUFFER_DATA_LENGTH(NET_BUFFER_LIST_FIRST_NB(Nbl));
UCHAR *NblData = MemGetValidatedNetBufferListData(Nbl);
MESSAGE_MACS *Macs = (MESSAGE_MACS *)(NblData + NblLen - sizeof(*Macs));
COOKIE_MAC_STATE Ret;
UINT8 ComputedMac[COOKIE_LEN];
UINT8 Cookie[COOKIE_LEN];
Ret = INVALID_MAC;
ComputeMac1(ComputedMac, NblData, NblLen, Checker->MessageMac1Key);
if (!CryptoEqualMemory16(ComputedMac, Macs->Mac1))
goto out;
Ret = VALID_MAC_BUT_NO_COOKIE;
if (!CheckCookie)
goto out;
MakeCookie(Cookie, NET_BUFFER_LIST_DATAGRAM_INDICATION(Nbl)->RemoteAddress, Checker);
ComputeMac2(ComputedMac, NblData, NblLen, Cookie);
if (!CryptoEqualMemory16(ComputedMac, Macs->Mac2))
goto out;
Ret = VALID_MAC_WITH_COOKIE_BUT_RATELIMITED;
if (!RatelimiterAllow(NET_BUFFER_LIST_DATAGRAM_INDICATION(Nbl)->RemoteAddress))
goto out;
Ret = VALID_MAC_WITH_COOKIE;
out:
return Ret;
}
_Use_decl_annotations_
VOID
CookieAddMacToPacket(VOID *Message, SIZE_T Len, WG_PEER *Peer)
{
MESSAGE_MACS *Macs = (MESSAGE_MACS *)((UINT8 *)Message + Len - sizeof(*Macs));
MuAcquirePushLockExclusive(&Peer->LatestCookie.Lock);
ComputeMac1(Macs->Mac1, Message, Len, Peer->LatestCookie.MessageMac1Key);
RtlCopyMemory(Peer->LatestCookie.LastMac1Sent, Macs->Mac1, COOKIE_LEN);
Peer->LatestCookie.HaveSentMac1 = TRUE;
MuReleasePushLockExclusive(&Peer->LatestCookie.Lock);
MuAcquirePushLockShared(&Peer->LatestCookie.Lock);
if (Peer->LatestCookie.IsValid &&
!BirthdateHasExpired(Peer->LatestCookie.Birthdate, COOKIE_SECRET_MAX_AGE - COOKIE_SECRET_LATENCY))
ComputeMac2(Macs->Mac2, Message, Len, Peer->LatestCookie.Cookie);
else
RtlZeroMemory(Macs->Mac2, COOKIE_LEN);
MuReleasePushLockShared(&Peer->LatestCookie.Lock);
}
_Use_decl_annotations_
VOID
CookieMessageCreate(MESSAGE_HANDSHAKE_COOKIE *Dst, CONST NET_BUFFER_LIST *Nbl, UINT32_LE Index, COOKIE_CHECKER *Checker)
{
CONST ULONG NblLen = NET_BUFFER_DATA_LENGTH(NET_BUFFER_LIST_FIRST_NB(Nbl));
UCHAR *NblData = MemGetValidatedNetBufferListData(Nbl);
MESSAGE_MACS *Macs = (MESSAGE_MACS *)(NblData + NblLen - sizeof(*Macs));
UINT8 Cookie[COOKIE_LEN];
Dst->Header.Type = CpuToLe32(MESSAGE_TYPE_HANDSHAKE_COOKIE);
Dst->ReceiverIndex = Index;
CryptoRandom(Dst->Nonce, COOKIE_NONCE_LEN);
MakeCookie(Cookie, NET_BUFFER_LIST_DATAGRAM_INDICATION(Nbl)->RemoteAddress, Checker);
XChaCha20Poly1305Encrypt(
Dst->EncryptedCookie, Cookie, COOKIE_LEN, Macs->Mac1, COOKIE_LEN, Dst->Nonce, Checker->CookieEncryptionKey);
}
_Use_decl_annotations_
VOID
CookieMessageConsume(MESSAGE_HANDSHAKE_COOKIE *Src, WG_DEVICE *Wg)
{
WG_PEER *Peer = NULL;
UINT8 Cookie[COOKIE_LEN];
BOOLEAN Ret;
if (!IndexHashtableLookup(
Wg->IndexHashtable, INDEX_HASHTABLE_HANDSHAKE | INDEX_HASHTABLE_KEYPAIR, Src->ReceiverIndex, &Peer))
return;
MuAcquirePushLockShared(&Peer->LatestCookie.Lock);
if (!Peer->LatestCookie.HaveSentMac1)
{
MuReleasePushLockShared(&Peer->LatestCookie.Lock);
goto out;
}
Ret = XChaCha20Poly1305Decrypt(
Cookie,
Src->EncryptedCookie,
sizeof(Src->EncryptedCookie),
Peer->LatestCookie.LastMac1Sent,
COOKIE_LEN,
Src->Nonce,
Peer->LatestCookie.CookieDecryptionKey);
MuReleasePushLockShared(&Peer->LatestCookie.Lock);
if (Ret)
{
MuAcquirePushLockExclusive(&Peer->LatestCookie.Lock);
RtlCopyMemory(Peer->LatestCookie.Cookie, Cookie, COOKIE_LEN);
Peer->LatestCookie.Birthdate = KeQueryInterruptTime();
Peer->LatestCookie.IsValid = TRUE;
Peer->LatestCookie.HaveSentMac1 = FALSE;
MuReleasePushLockExclusive(&Peer->LatestCookie.Lock);
}
else
LogInfoRatelimited(Wg, "Could not decrypt invalid cookie response");
out:
PeerPut(Peer);
}
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