Hesham/wintun
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Allow buffer mapping to happen concurrently

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Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2019-06-27 09:08:57 +00:00
parent 88bde5b28e
commit d82a68f830
1 changed files with 39 additions and 17 deletions
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56
wintun.c
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@ -112,9 +112,11 @@ typedef struct _TUN_CTX
typedef struct _TUN_MAPPED_UBUFFER
{
VOID *UserAddress, *KernelAddress;
VOID *volatile UserAddress;
VOID *KernelAddress;
MDL *Mdl;
ULONG Size;
FAST_MUTEX InitializationComplete;
// TODO: ThreadID for checking
} TUN_MAPPED_UBUFFER;
@ -295,38 +297,56 @@ _Must_inspect_result_
static NTSTATUS
TunMapUbuffer(_Inout_ TUN_MAPPED_UBUFFER *MappedBuffer, _In_ VOID *UserAddress, _In_ ULONG Size)
{
if (MappedBuffer->UserAddress)
VOID *current_uaddr = InterlockedGetPointer(&MappedBuffer->UserAddress);
if (current_uaddr)
{
if (UserAddress == MappedBuffer->UserAddress) // TODO: Check ThreadID
if (UserAddress == current_uaddr) // TODO: Check ThreadID
return STATUS_SUCCESS;
return STATUS_ALREADY_INITIALIZED;
}
NTSTATUS status = STATUS_SUCCESS;
ExAcquireFastMutex(&MappedBuffer->InitializationComplete);
// Recheck the same thing as above, but locked this time.
current_uaddr = InterlockedGetPointer(&MappedBuffer->UserAddress);
if (current_uaddr)
{
if (UserAddress != current_uaddr) // TODO: Check ThreadID
status = STATUS_ALREADY_INITIALIZED;
goto err_releasemutex;
}
MappedBuffer->Mdl = IoAllocateMdl(UserAddress, Size, FALSE, FALSE, NULL);
status = STATUS_INSUFFICIENT_RESOURCES;
if (!MappedBuffer->Mdl)
return STATUS_INSUFFICIENT_RESOURCES;
goto err_releasemutex;
status = STATUS_INVALID_USER_BUFFER;
try
{
MmProbeAndLockPages(MappedBuffer->Mdl, UserMode, IoWriteAccess);
}
except(EXCEPTION_EXECUTE_HANDLER)
{
IoFreeMdl(MappedBuffer->Mdl);
MappedBuffer->Mdl = NULL;
return STATUS_INVALID_USER_BUFFER;
}
except(EXCEPTION_EXECUTE_HANDLER) { goto err_freemdl; }
MappedBuffer->KernelAddress =
MmGetSystemAddressForMdlSafe(MappedBuffer->Mdl, NormalPagePriority | MdlMappingNoExecute);
status = STATUS_INSUFFICIENT_RESOURCES;
if (!MappedBuffer->KernelAddress)
{
MmUnlockPages(MappedBuffer->Mdl);
IoFreeMdl(MappedBuffer->Mdl);
MappedBuffer->Mdl = NULL;
return STATUS_INSUFFICIENT_RESOURCES;
}
MappedBuffer->UserAddress = UserAddress;
goto err_unlockmdl;
MappedBuffer->Size = Size;
InterlockedExchangePointer(&MappedBuffer->UserAddress, UserAddress);
ExReleaseFastMutex(&MappedBuffer->InitializationComplete);
return STATUS_SUCCESS;
err_unlockmdl:
MmUnlockPages(MappedBuffer->Mdl);
err_freemdl:
IoFreeMdl(MappedBuffer->Mdl);
MappedBuffer->Mdl = NULL;
err_releasemutex:
ExReleaseFastMutex(&MappedBuffer->InitializationComplete);
return status;
}
_IRQL_requires_max_(DISPATCH_LEVEL)
@ -974,6 +994,8 @@ TunDispatchCreate(_Inout_ TUN_CTX *Ctx, _Inout_ IRP *Irp)
if (!file_ctx)
return STATUS_INSUFFICIENT_RESOURCES;
RtlZeroMemory(file_ctx, sizeof(*file_ctx));
ExInitializeFastMutex(&file_ctx->ReadBuffer.InitializationComplete);
ExInitializeFastMutex(&file_ctx->WriteBuffer.InitializationComplete);
KIRQL irql = ExAcquireSpinLockShared(&Ctx->TransitionLock);
LONG flags = InterlockedGet(&Ctx->Flags);