/* $Id: DBGPlugInLinux.cpp $ */ /** @file * DBGPlugInLinux - Debugger and Guest OS Digger Plugin For Linux. */ /* * Copyright (C) 2008-2020 Oracle Corporation * * This file is part of VirtualBox Open Source Edition (OSE), as * available from http://www.virtualbox.org. This file is free software; * you can redistribute it and/or modify it under the terms of the GNU * General Public License (GPL) as published by the Free Software * Foundation, in version 2 as it comes in the "COPYING" file of the * VirtualBox OSE distribution. VirtualBox OSE is distributed in the * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind. */ /********************************************************************************************************************************* * Header Files * *********************************************************************************************************************************/ #define LOG_GROUP LOG_GROUP_DBGF /// @todo add new log group. #include "DBGPlugIns.h" #include "DBGPlugInCommonELF.h" #include #include #include #include #include #include #include #include #include #include /********************************************************************************************************************************* * Structures and Typedefs * *********************************************************************************************************************************/ /** @name InternalLinux structures * @{ */ /** @} */ /** * Config item type. */ typedef enum DBGDIGGERLINUXCFGITEMTYPE { /** Invalid type. */ DBGDIGGERLINUXCFGITEMTYPE_INVALID = 0, /** String. */ DBGDIGGERLINUXCFGITEMTYPE_STRING, /** Number. */ DBGDIGGERLINUXCFGITEMTYPE_NUMBER, /** Flag whether this feature is included in the * kernel or as a module. */ DBGDIGGERLINUXCFGITEMTYPE_FLAG } DBGDIGGERLINUXCFGITEMTYPE; /** * Item in the config database. */ typedef struct DBGDIGGERLINUXCFGITEM { /** String space core. */ RTSTRSPACECORE Core; /** Config item type. */ DBGDIGGERLINUXCFGITEMTYPE enmType; /** Data based on the type. */ union { /** Number. */ int64_t i64Num; /** Flag. */ bool fModule; /** String - variable in size. */ char aszString[1]; } u; } DBGDIGGERLINUXCFGITEM; /** Pointer to a config database item. */ typedef DBGDIGGERLINUXCFGITEM *PDBGDIGGERLINUXCFGITEM; /** Pointer to a const config database item. */ typedef const DBGDIGGERLINUXCFGITEM *PCDBGDIGGERLINUXCFGITEM; /** * Linux guest OS digger instance data. */ typedef struct DBGDIGGERLINUX { /** Whether the information is valid or not. * (For fending off illegal interface method calls.) */ bool fValid; /** Set if 64-bit, clear if 32-bit. */ bool f64Bit; /** Set if the kallsyms table uses relative addressing, clear * if absolute addresses are used. */ bool fRelKrnlAddr; /** The relative base when kernel symbols use offsets rather than * absolute addresses. */ RTGCUINTPTR uKernelRelativeBase; /** The address of the linux banner. * This is set during probing. */ DBGFADDRESS AddrLinuxBanner; /** Kernel base address. * This is set during probing, refined during kallsyms parsing. */ DBGFADDRESS AddrKernelBase; /** The kernel size. */ uint32_t cbKernel; /** The number of kernel symbols (kallsyms_num_syms). * This is set during init. */ uint32_t cKernelSymbols; /** The size of the kernel name table (sizeof(kallsyms_names)). */ uint32_t cbKernelNames; /** Number of entries in the kernel_markers table. */ uint32_t cKernelNameMarkers; /** The size of the kernel symbol token table. */ uint32_t cbKernelTokenTable; /** The address of the encoded kernel symbol names (kallsyms_names). */ DBGFADDRESS AddrKernelNames; /** The address of the kernel symbol addresses (kallsyms_addresses). */ DBGFADDRESS AddrKernelAddresses; /** The address of the kernel symbol name markers (kallsyms_markers). */ DBGFADDRESS AddrKernelNameMarkers; /** The address of the kernel symbol token table (kallsyms_token_table). */ DBGFADDRESS AddrKernelTokenTable; /** The address of the kernel symbol token index table (kallsyms_token_index). */ DBGFADDRESS AddrKernelTokenIndex; /** The kernel message log interface. */ DBGFOSIDMESG IDmesg; /** The config database root. */ RTSTRSPACE hCfgDb; } DBGDIGGERLINUX; /** Pointer to the linux guest OS digger instance data. */ typedef DBGDIGGERLINUX *PDBGDIGGERLINUX; /** * The current printk_log structure. */ typedef struct LNXPRINTKHDR { /** Monotonic timestamp. */ uint64_t nsTimestamp; /** The total size of this message record. */ uint16_t cbTotal; /** The size of the text part (immediately follows the header). */ uint16_t cbText; /** The size of the optional dictionary part (follows the text). */ uint16_t cbDict; /** The syslog facility number. */ uint8_t bFacility; /** First 5 bits are internal flags, next 3 bits are log level. */ uint8_t fFlagsAndLevel; } LNXPRINTKHDR; AssertCompileSize(LNXPRINTKHDR, 2*sizeof(uint64_t)); /** Pointer to linux printk_log header. */ typedef LNXPRINTKHDR *PLNXPRINTKHDR; /** Pointer to linux const printk_log header. */ typedef LNXPRINTKHDR const *PCLNXPRINTKHDR; /********************************************************************************************************************************* * Defined Constants And Macros * *********************************************************************************************************************************/ /** First kernel map address for 32bit Linux hosts (__START_KERNEL_map). */ #define LNX32_KERNEL_ADDRESS_START UINT32_C(0xc0000000) /** First kernel map address for 64bit Linux hosts (__START_KERNEL_map). */ #define LNX64_KERNEL_ADDRESS_START UINT64_C(0xffffffff80000000) /** Validates a 32-bit linux kernel address */ #define LNX32_VALID_ADDRESS(Addr) ((Addr) > UINT32_C(0x80000000) && (Addr) < UINT32_C(0xfffff000)) /** Validates a 64-bit linux kernel address */ #define LNX64_VALID_ADDRESS(Addr) ((Addr) > UINT64_C(0xffff800000000000) && (Addr) < UINT64_C(0xfffffffffffff000)) /** The max kernel size. */ #define LNX_MAX_KERNEL_SIZE UINT32_C(0x0f000000) /** Maximum kernel log buffer size. */ #define LNX_MAX_KERNEL_LOG_SIZE (16 * _1M) /** The maximum size we expect for kallsyms_names. */ #define LNX_MAX_KALLSYMS_NAMES_SIZE UINT32_C(0x200000) /** The maximum size we expect for kallsyms_token_table. */ #define LNX_MAX_KALLSYMS_TOKEN_TABLE_SIZE UINT32_C(0x10000) /** The minimum number of symbols we expect in kallsyms_num_syms. */ #define LNX_MIN_KALLSYMS_SYMBOLS UINT32_C(2048) /** The maximum number of symbols we expect in kallsyms_num_syms. */ #define LNX_MAX_KALLSYMS_SYMBOLS UINT32_C(1048576) /** The min length an encoded symbol in kallsyms_names is expected to have. */ #define LNX_MIN_KALLSYMS_ENC_LENGTH UINT8_C(1) /** The max length an encoded symbol in kallsyms_names is expected to have. * @todo check real life here. */ #define LNX_MAX_KALLSYMS_ENC_LENGTH UINT8_C(28) /** The approximate maximum length of a string token. */ #define LNX_MAX_KALLSYMS_TOKEN_LEN UINT16_C(32) /** Maximum compressed config size expected. */ #define LNX_MAX_COMPRESSED_CFG_SIZE _1M /** Module tag for linux ('linuxmod' on little endian ASCII systems). */ #define DIG_LNX_MOD_TAG UINT64_C(0x545f5d78758e898c) /********************************************************************************************************************************* * Internal Functions * *********************************************************************************************************************************/ static DECLCALLBACK(int) dbgDiggerLinuxInit(PUVM pUVM, void *pvData); /********************************************************************************************************************************* * Global Variables * *********************************************************************************************************************************/ /** Table of common linux kernel addresses. */ static uint64_t g_au64LnxKernelAddresses[] = { UINT64_C(0xc0100000), UINT64_C(0x90100000), UINT64_C(0xffffffff80200000) }; static const uint8_t g_abLinuxVersion[] = "Linux version "; /** The needle for searching for the kernel log area (the value is observed in pretty much all 32bit and 64bit x86 kernels). * This needle should appear only once in the memory due to the address being filled in by a format string. */ static const uint8_t g_abKrnlLogNeedle[] = "BIOS-e820: [mem 0x0000000000000000"; /** * Tries to resolve the kernel log buffer start and end by searching for needle. * * @returns VBox status code. * @param pThis The Linux digger data. * @param pUVM The VM handle. * @param pGCPtrLogBuf Where to store the start of the kernel log buffer on success. * @param pcbLogBuf Where to store the size of the kernel log buffer on success. */ static int dbgDiggerLinuxKrnlLogBufFindByNeedle(PDBGDIGGERLINUX pThis, PUVM pUVM, RTGCPTR *pGCPtrLogBuf, uint32_t *pcbLogBuf) { int rc = VINF_SUCCESS; /* Try to find the needle, it should be very early in the kernel log buffer. */ DBGFADDRESS AddrScan; DBGFADDRESS AddrHit; DBGFR3AddrFromFlat(pUVM, &AddrScan, pThis->f64Bit ? LNX64_KERNEL_ADDRESS_START : LNX32_KERNEL_ADDRESS_START); rc = DBGFR3MemScan(pUVM, 0 /*idCpu*/, &AddrScan, ~(RTGCUINTPTR)0, 1 /*uAlign*/, g_abKrnlLogNeedle, sizeof(g_abKrnlLogNeedle) - 1, &AddrHit); if (RT_SUCCESS(rc)) { uint32_t cbLogBuf = 0; uint64_t tsLastNs = 0; DBGFADDRESS AddrCur; DBGFR3AddrSub(&AddrHit, sizeof(LNXPRINTKHDR)); AddrCur = AddrHit; /* Try to find the end of the kernel log buffer. */ for (;;) { if (cbLogBuf >= LNX_MAX_KERNEL_LOG_SIZE) break; LNXPRINTKHDR Hdr; rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, &AddrCur, &Hdr, sizeof(Hdr)); if (RT_SUCCESS(rc)) { uint32_t const cbLogAlign = 4; /* * If the header does not look valid anymore we stop. * Timestamps are monotonically increasing. */ if ( !Hdr.cbTotal /* Zero entry size means there is no record anymore, doesn't make sense to look futher. */ || Hdr.cbText + Hdr.cbDict + sizeof(Hdr) > Hdr.cbTotal || (Hdr.cbTotal & (cbLogAlign - 1)) != 0 || tsLastNs > Hdr.nsTimestamp) break; /** @todo Maybe read text part and verify it is all ASCII. */ cbLogBuf += Hdr.cbTotal; DBGFR3AddrAdd(&AddrCur, Hdr.cbTotal); } if (RT_FAILURE(rc)) break; } /** @todo Go back to find the start address of the kernel log (or we loose potential kernel log messages). */ if ( RT_SUCCESS(rc) && cbLogBuf) { /* Align log buffer size to a power of two. */ uint32_t idxBitLast = ASMBitLastSetU32(cbLogBuf); idxBitLast--; /* There is at least one bit set, see check above. */ if (cbLogBuf & (RT_BIT_32(idxBitLast) - 1)) idxBitLast++; *pGCPtrLogBuf = AddrHit.FlatPtr; *pcbLogBuf = RT_MIN(RT_BIT_32(idxBitLast), LNX_MAX_KERNEL_LOG_SIZE); } else if (RT_SUCCESS(rc)) rc = VERR_NOT_FOUND; } return rc; } /** * Converts a given offset into an absolute address if relative kernel offsets are used for * kallsyms. * * @returns The absolute kernel address. * @param pThis The Linux digger data. * @param uOffset The offset to convert. */ DECLINLINE(RTGCUINTPTR) dbgDiggerLinuxConvOffsetToAddr(PDBGDIGGERLINUX pThis, int32_t uOffset) { RTGCUINTPTR uAddr; /* * How the absolute address is calculated from the offset depends on the * CONFIG_KALLSYMS_ABSOLUTE_PERCPU config which is only set for 64bit * SMP kernels (we assume that all 64bit kernels always have SMP enabled too). */ if (pThis->f64Bit) { if (uOffset >= 0) uAddr = uOffset; else uAddr = pThis->uKernelRelativeBase - 1 - uOffset; } else uAddr = pThis->uKernelRelativeBase + (uint32_t)uOffset; return uAddr; } /** * Disassembles a simple getter returning the value for it. * * @returns VBox status code. * @param pThis The Linux digger data. * @param pUVM The VM handle. * @param hMod The module to use. * @param pszSymbol The symbol of the getter. * @param pvVal Where to store the value on success. * @param cbVal Size of the value in bytes. */ static int dbgDiggerLinuxDisassembleSimpleGetter(PDBGDIGGERLINUX pThis, PUVM pUVM, RTDBGMOD hMod, const char *pszSymbol, void *pvVal, uint32_t cbVal) { int rc = VINF_SUCCESS; RTDBGSYMBOL SymInfo; rc = RTDbgModSymbolByName(hMod, pszSymbol, &SymInfo); if (RT_SUCCESS(rc)) { /* * Do the diassembling. Disassemble until a ret instruction is encountered * or a limit is reached (don't want to disassemble for too long as the getter * should be short). * push and pop instructions are skipped as well as any mov instructions not * touching the rax or eax register (depending on the size of the value). */ unsigned cInstrDisassembled = 0; uint32_t offInstr = 0; bool fRet = false; DISSTATE DisState; RT_ZERO(DisState); do { DBGFADDRESS Addr; RTGCPTR GCPtrCur = (RTGCPTR)SymInfo.Value + pThis->AddrKernelBase.FlatPtr + offInstr; DBGFR3AddrFromFlat(pUVM, &Addr, GCPtrCur); /* Prefetch the instruction. */ uint8_t abInstr[32]; rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, &Addr, &abInstr[0], sizeof(abInstr)); if (RT_SUCCESS(rc)) { uint32_t cbInstr = 0; rc = DISInstr(&abInstr[0], pThis->f64Bit ? DISCPUMODE_64BIT : DISCPUMODE_32BIT, &DisState, &cbInstr); if (RT_SUCCESS(rc)) { switch (DisState.pCurInstr->uOpcode) { case OP_PUSH: case OP_POP: case OP_NOP: case OP_LEA: break; case OP_RETN: /* Getter returned, abort disassembling. */ fRet = true; break; case OP_MOV: /* * Check that the destination is either rax or eax depending on the * value size. * * Param1 is the destination and Param2 the source. */ if ( ( ( (DisState.Param1.fUse & (DISUSE_BASE | DISUSE_REG_GEN32)) && cbVal == sizeof(uint32_t)) || ( (DisState.Param1.fUse & (DISUSE_BASE | DISUSE_REG_GEN64)) && cbVal == sizeof(uint64_t))) && DisState.Param1.Base.idxGenReg == DISGREG_RAX) { /* Parse the source. */ if (DisState.Param2.fUse & (DISUSE_IMMEDIATE32 | DISUSE_IMMEDIATE64)) memcpy(pvVal, &DisState.Param2.uValue, cbVal); else if (DisState.Param2.fUse & (DISUSE_RIPDISPLACEMENT32|DISUSE_DISPLACEMENT32|DISUSE_DISPLACEMENT64)) { RTGCPTR GCPtrVal = 0; if (DisState.Param2.fUse & DISUSE_RIPDISPLACEMENT32) GCPtrVal = GCPtrCur + DisState.Param2.uDisp.i32 + cbInstr; else if (DisState.Param2.fUse & DISUSE_DISPLACEMENT32) GCPtrVal = (RTGCPTR)DisState.Param2.uDisp.u32; else if (DisState.Param2.fUse & DISUSE_DISPLACEMENT64) GCPtrVal = (RTGCPTR)DisState.Param2.uDisp.u64; else AssertMsgFailedBreakStmt(("Invalid displacement\n"), rc = VERR_INVALID_STATE); DBGFADDRESS AddrVal; rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, DBGFR3AddrFromFlat(pUVM, &AddrVal, GCPtrVal), pvVal, cbVal); } } break; default: /* All other instructions will cause an error for now (playing safe here). */ rc = VERR_INVALID_PARAMETER; break; } cInstrDisassembled++; offInstr += cbInstr; } } } while ( RT_SUCCESS(rc) && cInstrDisassembled < 20 && !fRet); } return rc; } /** * Try to get at the log buffer starting address and size by disassembling emit_log_char. * * @returns VBox status code. * @param pThis The Linux digger data. * @param pUVM The VM handle. * @param hMod The module to use. * @param pGCPtrLogBuf Where to store the log buffer pointer on success. * @param pcbLogBuf Where to store the size of the log buffer on success. */ static int dbgDiggerLinuxQueryAsciiLogBufferPtrs(PDBGDIGGERLINUX pThis, PUVM pUVM, RTDBGMOD hMod, RTGCPTR *pGCPtrLogBuf, uint32_t *pcbLogBuf) { int rc = VINF_SUCCESS; /** * We disassemble emit_log_char to get at the log buffer address and size. * This is used in case the symbols are not exported in kallsyms. * * This is what it typically looks like: * vmlinux!emit_log_char: * %00000000c01204a1 56 push esi * %00000000c01204a2 8b 35 d0 1c 34 c0 mov esi, dword [0c0341cd0h] * %00000000c01204a8 53 push ebx * %00000000c01204a9 8b 1d 74 3b 3e c0 mov ebx, dword [0c03e3b74h] * %00000000c01204af 8b 0d d8 1c 34 c0 mov ecx, dword [0c0341cd8h] * %00000000c01204b5 8d 56 ff lea edx, [esi-001h] * %00000000c01204b8 21 da and edx, ebx * %00000000c01204ba 88 04 11 mov byte [ecx+edx], al * %00000000c01204bd 8d 53 01 lea edx, [ebx+001h] * %00000000c01204c0 89 d0 mov eax, edx * [...] */ RTDBGSYMBOL SymInfo; rc = RTDbgModSymbolByName(hMod, "emit_log_char", &SymInfo); if (RT_SUCCESS(rc)) { /* * Do the diassembling. Disassemble until a ret instruction is encountered * or a limit is reached (don't want to disassemble for too long as the getter * should be short). Certain instructions found are ignored (push, nop, etc.). */ unsigned cInstrDisassembled = 0; uint32_t offInstr = 0; bool fRet = false; DISSTATE DisState; unsigned cAddressesUsed = 0; struct { size_t cb; RTGCPTR GCPtrOrigSrc; } aAddresses[5]; RT_ZERO(DisState); RT_ZERO(aAddresses); do { DBGFADDRESS Addr; RTGCPTR GCPtrCur = (RTGCPTR)SymInfo.Value + pThis->AddrKernelBase.FlatPtr + offInstr; DBGFR3AddrFromFlat(pUVM, &Addr, GCPtrCur); /* Prefetch the instruction. */ uint8_t abInstr[32]; rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, &Addr, &abInstr[0], sizeof(abInstr)); if (RT_SUCCESS(rc)) { uint32_t cbInstr = 0; rc = DISInstr(&abInstr[0], pThis->f64Bit ? DISCPUMODE_64BIT : DISCPUMODE_32BIT, &DisState, &cbInstr); if (RT_SUCCESS(rc)) { switch (DisState.pCurInstr->uOpcode) { case OP_PUSH: case OP_POP: case OP_NOP: case OP_LEA: case OP_AND: case OP_CBW: case OP_DEC: break; case OP_RETN: /* emit_log_char returned, abort disassembling. */ rc = VERR_NOT_FOUND; fRet = true; break; case OP_MOV: case OP_MOVSXD: /* * If a mov is encountered writing to memory with al (or dil for amd64) being the source the * character is stored and we can infer the base address and size of the log buffer from * the source addresses. */ if ( (DisState.Param2.fUse & DISUSE_REG_GEN8) && ( (DisState.Param2.Base.idxGenReg == DISGREG_AL && !pThis->f64Bit) || (DisState.Param2.Base.idxGenReg == DISGREG_DIL && pThis->f64Bit)) && DISUSE_IS_EFFECTIVE_ADDR(DisState.Param1.fUse)) { RTGCPTR GCPtrLogBuf = 0; uint32_t cbLogBuf = 0; /* * We can stop disassembling now and inspect all registers, look for a valid kernel address first. * Only one of the accessed registers should hold a valid kernel address. * For the log size look for the biggest non kernel address. */ for (unsigned i = 0; i < cAddressesUsed; i++) { DBGFADDRESS AddrVal; union { uint8_t abVal[8]; uint32_t u32Val; uint64_t u64Val; } Val; rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, DBGFR3AddrFromFlat(pUVM, &AddrVal, aAddresses[i].GCPtrOrigSrc), &Val.abVal[0], aAddresses[i].cb); if (RT_SUCCESS(rc)) { if (pThis->f64Bit && aAddresses[i].cb == sizeof(uint64_t)) { if (LNX64_VALID_ADDRESS(Val.u64Val)) { if (GCPtrLogBuf == 0) GCPtrLogBuf = Val.u64Val; else { rc = VERR_NOT_FOUND; break; } } } else { AssertMsgBreakStmt(aAddresses[i].cb == sizeof(uint32_t), ("Invalid value size\n"), rc = VERR_INVALID_STATE); /* Might be a kernel address or a size indicator. */ if (!pThis->f64Bit && LNX32_VALID_ADDRESS(Val.u32Val)) { if (GCPtrLogBuf == 0) GCPtrLogBuf = Val.u32Val; else { rc = VERR_NOT_FOUND; break; } } else { /* * The highest value will be the log buffer because the other * accessed variables are indexes into the buffer and hence * always smaller than the size. */ if (cbLogBuf < Val.u32Val) cbLogBuf = Val.u32Val; } } } } if ( RT_SUCCESS(rc) && GCPtrLogBuf != 0 && cbLogBuf != 0) { *pGCPtrLogBuf = GCPtrLogBuf; *pcbLogBuf = cbLogBuf; } else if (RT_SUCCESS(rc)) rc = VERR_NOT_FOUND; fRet = true; break; } else { /* * In case of a memory to register move store the destination register index and the * source address in the relation table for later processing. */ if ( (DisState.Param1.fUse & (DISUSE_BASE | DISUSE_REG_GEN32 | DISUSE_REG_GEN64)) && (DisState.Param2.cb == sizeof(uint32_t) || DisState.Param2.cb == sizeof(uint64_t)) && (DisState.Param2.fUse & (DISUSE_RIPDISPLACEMENT32|DISUSE_DISPLACEMENT32|DISUSE_DISPLACEMENT64))) { RTGCPTR GCPtrVal = 0; if (DisState.Param2.fUse & DISUSE_RIPDISPLACEMENT32) GCPtrVal = GCPtrCur + DisState.Param2.uDisp.i32 + cbInstr; else if (DisState.Param2.fUse & DISUSE_DISPLACEMENT32) GCPtrVal = (RTGCPTR)DisState.Param2.uDisp.u32; else if (DisState.Param2.fUse & DISUSE_DISPLACEMENT64) GCPtrVal = (RTGCPTR)DisState.Param2.uDisp.u64; else AssertMsgFailedBreakStmt(("Invalid displacement\n"), rc = VERR_INVALID_STATE); if (cAddressesUsed < RT_ELEMENTS(aAddresses)) { /* movsxd reads always 32bits. */ if (DisState.pCurInstr->uOpcode == OP_MOVSXD) aAddresses[cAddressesUsed].cb = sizeof(uint32_t); else aAddresses[cAddressesUsed].cb = DisState.Param2.cb; aAddresses[cAddressesUsed].GCPtrOrigSrc = GCPtrVal; cAddressesUsed++; } else { rc = VERR_INVALID_PARAMETER; break; } } } break; default: /* All other instructions will cause an error for now (playing safe here). */ rc = VERR_INVALID_PARAMETER; break; } cInstrDisassembled++; offInstr += cbInstr; } } } while ( RT_SUCCESS(rc) && cInstrDisassembled < 20 && !fRet); } return rc; } /** * Try to get at the log buffer starting address and size by disassembling some exposed helpers. * * @returns VBox status code. * @param pThis The Linux digger data. * @param pUVM The VM handle. * @param hMod The module to use. * @param pGCPtrLogBuf Where to store the log buffer pointer on success. * @param pcbLogBuf Where to store the size of the log buffer on success. */ static int dbgDiggerLinuxQueryLogBufferPtrs(PDBGDIGGERLINUX pThis, PUVM pUVM, RTDBGMOD hMod, RTGCPTR *pGCPtrLogBuf, uint32_t *pcbLogBuf) { int rc = VINF_SUCCESS; struct { void *pvVar; uint32_t cbHost, cbGuest; const char *pszSymbol; } aSymbols[] = { { pGCPtrLogBuf, (uint32_t)sizeof(RTGCPTR), (uint32_t)(pThis->f64Bit ? sizeof(uint64_t) : sizeof(uint32_t)), "log_buf_addr_get" }, { pcbLogBuf, (uint32_t)sizeof(uint32_t), (uint32_t)sizeof(uint32_t), "log_buf_len_get" } }; for (uint32_t i = 0; i < RT_ELEMENTS(aSymbols) && RT_SUCCESS(rc); i++) { RT_BZERO(aSymbols[i].pvVar, aSymbols[i].cbHost); Assert(aSymbols[i].cbHost >= aSymbols[i].cbGuest); rc = dbgDiggerLinuxDisassembleSimpleGetter(pThis, pUVM, hMod, aSymbols[i].pszSymbol, aSymbols[i].pvVar, aSymbols[i].cbGuest); } return rc; } /** * Returns whether the log buffer is a simple ascii buffer or a record based implementation * based on the kernel version found. * * @returns Flag whether the log buffer is the simple ascii buffer. * @param pThis The Linux digger data. * @param pUVM The user mode VM handle. */ static bool dbgDiggerLinuxLogBufferIsAsciiBuffer(PDBGDIGGERLINUX pThis, PUVM pUVM) { char szTmp[128]; char const *pszVer = &szTmp[sizeof(g_abLinuxVersion) - 1]; RT_ZERO(szTmp); int rc = DBGFR3MemReadString(pUVM, 0, &pThis->AddrLinuxBanner, szTmp, sizeof(szTmp) - 1); if ( RT_SUCCESS(rc) && RTStrVersionCompare(pszVer, "3.4") == -1) return true; return false; } /** * Worker to get at the kernel log for pre 3.4 kernels where the log buffer was just a char buffer. * * @returns VBox status code. * @param pThis The Linux digger data. * @param pUVM The VM user mdoe handle. * @param hMod The debug module handle. * @param fFlags Flags reserved for future use, MBZ. * @param cMessages The number of messages to retrieve, counting from the * end of the log (i.e. like tail), use UINT32_MAX for all. * @param pszBuf The output buffer. * @param cbBuf The buffer size. * @param pcbActual Where to store the number of bytes actually returned, * including zero terminator. On VERR_BUFFER_OVERFLOW this * holds the necessary buffer size. Optional. */ static int dbgDiggerLinuxLogBufferQueryAscii(PDBGDIGGERLINUX pThis, PUVM pUVM, RTDBGMOD hMod, uint32_t fFlags, uint32_t cMessages, char *pszBuf, size_t cbBuf, size_t *pcbActual) { RT_NOREF2(fFlags, cMessages); int rc = VINF_SUCCESS; RTGCPTR GCPtrLogBuf; uint32_t cbLogBuf; struct { void *pvVar; size_t cbHost, cbGuest; const char *pszSymbol; } aSymbols[] = { { &GCPtrLogBuf, sizeof(GCPtrLogBuf), pThis->f64Bit ? sizeof(uint64_t) : sizeof(uint32_t), "log_buf" }, { &cbLogBuf, sizeof(cbLogBuf), sizeof(cbLogBuf), "log_buf_len" }, }; for (uint32_t i = 0; i < RT_ELEMENTS(aSymbols); i++) { RTDBGSYMBOL SymInfo; rc = RTDbgModSymbolByName(hMod, aSymbols[i].pszSymbol, &SymInfo); if (RT_SUCCESS(rc)) { RT_BZERO(aSymbols[i].pvVar, aSymbols[i].cbHost); Assert(aSymbols[i].cbHost >= aSymbols[i].cbGuest); DBGFADDRESS Addr; rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, DBGFR3AddrFromFlat(pUVM, &Addr, (RTGCPTR)SymInfo.Value + pThis->AddrKernelBase.FlatPtr), aSymbols[i].pvVar, aSymbols[i].cbGuest); if (RT_SUCCESS(rc)) continue; LogRel(("dbgDiggerLinuxIDmsg_QueryKernelLog: Reading '%s' at %RGv: %Rrc\n", aSymbols[i].pszSymbol, Addr.FlatPtr, rc)); } else LogRel(("dbgDiggerLinuxIDmsg_QueryKernelLog: Error looking up '%s': %Rrc\n", aSymbols[i].pszSymbol, rc)); rc = VERR_NOT_FOUND; break; } /* * Some kernels don't expose the variables in kallsyms so we have to try disassemble * some public helpers to get at the addresses. * * @todo: Maybe cache those values so we don't have to do the heavy work every time? */ if (rc == VERR_NOT_FOUND) { rc = dbgDiggerLinuxQueryAsciiLogBufferPtrs(pThis, pUVM, hMod, &GCPtrLogBuf, &cbLogBuf); if (RT_FAILURE(rc)) return rc; } /* * Check if the values make sense. */ if (pThis->f64Bit ? !LNX64_VALID_ADDRESS(GCPtrLogBuf) : !LNX32_VALID_ADDRESS(GCPtrLogBuf)) { LogRel(("dbgDiggerLinuxIDmsg_QueryKernelLog: 'log_buf' value %RGv is not valid.\n", GCPtrLogBuf)); return VERR_NOT_FOUND; } if ( cbLogBuf < 4096 || !RT_IS_POWER_OF_TWO(cbLogBuf) || cbLogBuf > 16*_1M) { LogRel(("dbgDiggerLinuxIDmsg_QueryKernelLog: 'log_buf_len' value %#x is not valid.\n", cbLogBuf)); return VERR_NOT_FOUND; } /* * Read the whole log buffer. */ uint8_t *pbLogBuf = (uint8_t *)RTMemAlloc(cbLogBuf); if (!pbLogBuf) { LogRel(("dbgDiggerLinuxIDmsg_QueryKernelLog: Failed to allocate %#x bytes for log buffer\n", cbLogBuf)); return VERR_NO_MEMORY; } DBGFADDRESS Addr; rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, DBGFR3AddrFromFlat(pUVM, &Addr, GCPtrLogBuf), pbLogBuf, cbLogBuf); if (RT_FAILURE(rc)) { LogRel(("dbgDiggerLinuxIDmsg_QueryKernelLog: Error reading %#x bytes of log buffer at %RGv: %Rrc\n", cbLogBuf, Addr.FlatPtr, rc)); RTMemFree(pbLogBuf); return VERR_NOT_FOUND; } /** @todo Try to parse where the single messages start to make use of cMessages. */ size_t cchLength = RTStrNLen((const char *)pbLogBuf, cbLogBuf); memcpy(&pszBuf[0], pbLogBuf, RT_MIN(cbBuf, cchLength)); /* Done with the buffer. */ RTMemFree(pbLogBuf); /* Set return size value. */ if (pcbActual) *pcbActual = RT_MIN(cbBuf, cchLength); return cbBuf <= cchLength ? VERR_BUFFER_OVERFLOW : VINF_SUCCESS; } /** * Worker to process a given record based kernel log. * * @returns VBox status code. * @param pThis The Linux digger data. * @param pUVM The VM user mode handle. * @param GCPtrLogBuf Flat guest address of the start of the log buffer. * @param cbLogBuf Power of two aligned size of the log buffer. * @param idxFirst Index in the log bfufer of the first message. * @param idxNext Index where to write hte next message in the log buffer. * @param fFlags Flags reserved for future use, MBZ. * @param cMessages The number of messages to retrieve, counting from the * end of the log (i.e. like tail), use UINT32_MAX for all. * @param pszBuf The output buffer. * @param cbBuf The buffer size. * @param pcbActual Where to store the number of bytes actually returned, * including zero terminator. On VERR_BUFFER_OVERFLOW this * holds the necessary buffer size. Optional. */ static int dbgDiggerLinuxKrnLogBufferProcess(PDBGDIGGERLINUX pThis, PUVM pUVM, RTGCPTR GCPtrLogBuf, uint32_t cbLogBuf, uint32_t idxFirst, uint32_t idxNext, uint32_t fFlags, uint32_t cMessages, char *pszBuf, size_t cbBuf, size_t *pcbActual) { RT_NOREF(fFlags); /* * Check if the values make sense. */ if (pThis->f64Bit ? !LNX64_VALID_ADDRESS(GCPtrLogBuf) : !LNX32_VALID_ADDRESS(GCPtrLogBuf)) { LogRel(("dbgDiggerLinuxIDmsg_QueryKernelLog: 'log_buf' value %RGv is not valid.\n", GCPtrLogBuf)); return VERR_NOT_FOUND; } if ( cbLogBuf < _4K || !RT_IS_POWER_OF_TWO(cbLogBuf) || cbLogBuf > LNX_MAX_KERNEL_LOG_SIZE) { LogRel(("dbgDiggerLinuxIDmsg_QueryKernelLog: 'log_buf_len' value %#x is not valid.\n", cbLogBuf)); return VERR_NOT_FOUND; } uint32_t const cbLogAlign = 4; if ( idxFirst > cbLogBuf - sizeof(LNXPRINTKHDR) || (idxFirst & (cbLogAlign - 1)) != 0) { LogRel(("dbgDiggerLinuxIDmsg_QueryKernelLog: 'log_first_idx' value %#x is not valid.\n", idxFirst)); return VERR_NOT_FOUND; } if ( idxNext > cbLogBuf - sizeof(LNXPRINTKHDR) || (idxNext & (cbLogAlign - 1)) != 0) { LogRel(("dbgDiggerLinuxIDmsg_QueryKernelLog: 'log_next_idx' value %#x is not valid.\n", idxNext)); return VERR_NOT_FOUND; } /* * Read the whole log buffer. */ uint8_t *pbLogBuf = (uint8_t *)RTMemAlloc(cbLogBuf); if (!pbLogBuf) { LogRel(("dbgDiggerLinuxIDmsg_QueryKernelLog: Failed to allocate %#x bytes for log buffer\n", cbLogBuf)); return VERR_NO_MEMORY; } DBGFADDRESS Addr; int rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, DBGFR3AddrFromFlat(pUVM, &Addr, GCPtrLogBuf), pbLogBuf, cbLogBuf); if (RT_FAILURE(rc)) { LogRel(("dbgDiggerLinuxIDmsg_QueryKernelLog: Error reading %#x bytes of log buffer at %RGv: %Rrc\n", cbLogBuf, Addr.FlatPtr, rc)); RTMemFree(pbLogBuf); return VERR_NOT_FOUND; } /* * Count the messages in the buffer while doing some basic validation. */ uint32_t const cbUsed = idxFirst == idxNext ? cbLogBuf /* could be empty... */ : idxFirst < idxNext ? idxNext - idxFirst : cbLogBuf - idxFirst + idxNext; uint32_t cbLeft = cbUsed; uint32_t offCur = idxFirst; uint32_t cLogMsgs = 0; while (cbLeft > 0) { PCLNXPRINTKHDR pHdr = (PCLNXPRINTKHDR)&pbLogBuf[offCur]; if (!pHdr->cbTotal) { /* Wrap around packet, most likely... */ if (cbLogBuf - offCur >= cbLeft) break; offCur = 0; pHdr = (PCLNXPRINTKHDR)&pbLogBuf[offCur]; } if (RT_UNLIKELY( pHdr->cbTotal > cbLogBuf - sizeof(*pHdr) - offCur || pHdr->cbTotal > cbLeft || (pHdr->cbTotal & (cbLogAlign - 1)) != 0 || pHdr->cbTotal < (uint32_t)pHdr->cbText + (uint32_t)pHdr->cbDict + sizeof(*pHdr) )) { LogRel(("dbgDiggerLinuxIDmsg_QueryKernelLog: Invalid printk_log record at %#x: cbTotal=%#x cbText=%#x cbDict=%#x cbLogBuf=%#x cbLeft=%#x\n", offCur, pHdr->cbTotal, pHdr->cbText, pHdr->cbDict, cbLogBuf, cbLeft)); break; } if (pHdr->cbText > 0) cLogMsgs++; /* next */ offCur += pHdr->cbTotal; cbLeft -= pHdr->cbTotal; } if (!cLogMsgs) { RTMemFree(pbLogBuf); return VERR_NOT_FOUND; } /* * Copy the messages into the output buffer. */ offCur = idxFirst; cbLeft = cbUsed - cbLeft; /* Skip messages that the caller doesn't want. */ if (cMessages < cLogMsgs) { uint32_t cToSkip = cLogMsgs - cMessages; cLogMsgs -= cToSkip; while (cToSkip > 0) { PCLNXPRINTKHDR pHdr = (PCLNXPRINTKHDR)&pbLogBuf[offCur]; if (!pHdr->cbTotal) { offCur = 0; pHdr = (PCLNXPRINTKHDR)&pbLogBuf[offCur]; } if (pHdr->cbText > 0) cToSkip--; /* next */ offCur += pHdr->cbTotal; cbLeft -= pHdr->cbTotal; } } /* Now copy the messages. */ size_t offDst = 0; while (cbLeft > 0) { PCLNXPRINTKHDR pHdr = (PCLNXPRINTKHDR)&pbLogBuf[offCur]; if ( !pHdr->cbTotal || !cLogMsgs) { if (cbLogBuf - offCur >= cbLeft) break; offCur = 0; pHdr = (PCLNXPRINTKHDR)&pbLogBuf[offCur]; } if (pHdr->cbText > 0) { char *pchText = (char *)(pHdr + 1); size_t cchText = RTStrNLen(pchText, pHdr->cbText); if (offDst + cchText < cbBuf) { memcpy(&pszBuf[offDst], pHdr + 1, cchText); pszBuf[offDst + cchText] = '\n'; } else if (offDst < cbBuf) memcpy(&pszBuf[offDst], pHdr + 1, cbBuf - offDst); offDst += cchText + 1; } /* next */ offCur += pHdr->cbTotal; cbLeft -= pHdr->cbTotal; } /* Done with the buffer. */ RTMemFree(pbLogBuf); /* Make sure we've reserved a char for the terminator. */ if (!offDst) offDst = 1; /* Set return size value. */ if (pcbActual) *pcbActual = offDst; if (offDst <= cbBuf) return VINF_SUCCESS; return VERR_BUFFER_OVERFLOW; } /** * Worker to get at the kernel log for post 3.4 kernels where the log buffer contains records. * * @returns VBox status code. * @param pThis The Linux digger data. * @param pUVM The VM user mdoe handle. * @param hMod The debug module handle. * @param fFlags Flags reserved for future use, MBZ. * @param cMessages The number of messages to retrieve, counting from the * end of the log (i.e. like tail), use UINT32_MAX for all. * @param pszBuf The output buffer. * @param cbBuf The buffer size. * @param pcbActual Where to store the number of bytes actually returned, * including zero terminator. On VERR_BUFFER_OVERFLOW this * holds the necessary buffer size. Optional. */ static int dbgDiggerLinuxLogBufferQueryRecords(PDBGDIGGERLINUX pThis, PUVM pUVM, RTDBGMOD hMod, uint32_t fFlags, uint32_t cMessages, char *pszBuf, size_t cbBuf, size_t *pcbActual) { int rc = VINF_SUCCESS; RTGCPTR GCPtrLogBuf; uint32_t cbLogBuf; uint32_t idxFirst; uint32_t idxNext; struct { void *pvVar; size_t cbHost, cbGuest; const char *pszSymbol; } aSymbols[] = { { &GCPtrLogBuf, sizeof(GCPtrLogBuf), pThis->f64Bit ? sizeof(uint64_t) : sizeof(uint32_t), "log_buf" }, { &cbLogBuf, sizeof(cbLogBuf), sizeof(cbLogBuf), "log_buf_len" }, { &idxFirst, sizeof(idxFirst), sizeof(idxFirst), "log_first_idx" }, { &idxNext, sizeof(idxNext), sizeof(idxNext), "log_next_idx" }, }; for (uint32_t i = 0; i < RT_ELEMENTS(aSymbols); i++) { RTDBGSYMBOL SymInfo; rc = RTDbgModSymbolByName(hMod, aSymbols[i].pszSymbol, &SymInfo); if (RT_SUCCESS(rc)) { RT_BZERO(aSymbols[i].pvVar, aSymbols[i].cbHost); Assert(aSymbols[i].cbHost >= aSymbols[i].cbGuest); DBGFADDRESS Addr; rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, DBGFR3AddrFromFlat(pUVM, &Addr, (RTGCPTR)SymInfo.Value + pThis->AddrKernelBase.FlatPtr), aSymbols[i].pvVar, aSymbols[i].cbGuest); if (RT_SUCCESS(rc)) continue; LogRel(("dbgDiggerLinuxIDmsg_QueryKernelLog: Reading '%s' at %RGv: %Rrc\n", aSymbols[i].pszSymbol, Addr.FlatPtr, rc)); } else LogRel(("dbgDiggerLinuxIDmsg_QueryKernelLog: Error looking up '%s': %Rrc\n", aSymbols[i].pszSymbol, rc)); rc = VERR_NOT_FOUND; break; } /* * Some kernels don't expose the variables in kallsyms so we have to try disassemble * some public helpers to get at the addresses. * * @todo: Maybe cache those values so we don't have to do the heavy work every time? */ if (rc == VERR_NOT_FOUND) { idxFirst = 0; idxNext = 0; rc = dbgDiggerLinuxQueryLogBufferPtrs(pThis, pUVM, hMod, &GCPtrLogBuf, &cbLogBuf); if (RT_FAILURE(rc)) { /* * Last resort, scan for a known value which should appear only once in the kernel log buffer * and try to deduce the boundaries from there. */ rc = dbgDiggerLinuxKrnlLogBufFindByNeedle(pThis, pUVM, &GCPtrLogBuf, &cbLogBuf); return rc; } } return dbgDiggerLinuxKrnLogBufferProcess(pThis, pUVM, GCPtrLogBuf, cbLogBuf, idxFirst, idxNext, fFlags, cMessages, pszBuf, cbBuf, pcbActual); } /** * @interface_method_impl{DBGFOSIDMESG,pfnQueryKernelLog} */ static DECLCALLBACK(int) dbgDiggerLinuxIDmsg_QueryKernelLog(PDBGFOSIDMESG pThis, PUVM pUVM, uint32_t fFlags, uint32_t cMessages, char *pszBuf, size_t cbBuf, size_t *pcbActual) { PDBGDIGGERLINUX pData = RT_FROM_MEMBER(pThis, DBGDIGGERLINUX, IDmesg); if (cMessages < 1) return VERR_INVALID_PARAMETER; /* * Resolve the symbols we need and read their values. */ RTDBGAS hAs = DBGFR3AsResolveAndRetain(pUVM, DBGF_AS_KERNEL); RTDBGMOD hMod; int rc = RTDbgAsModuleByName(hAs, "vmlinux", 0, &hMod); RTDbgAsRelease(hAs); size_t cbActual = 0; if (RT_SUCCESS(rc)) { /* * Check whether the kernel log buffer is a simple char buffer or the newer * record based implementation. * The record based implementation was presumably introduced with kernel 3.4, * see: http://thread.gmane.org/gmane.linux.kernel/1284184 */ if (dbgDiggerLinuxLogBufferIsAsciiBuffer(pData, pUVM)) rc = dbgDiggerLinuxLogBufferQueryAscii(pData, pUVM, hMod, fFlags, cMessages, pszBuf, cbBuf, &cbActual); else rc = dbgDiggerLinuxLogBufferQueryRecords(pData, pUVM, hMod, fFlags, cMessages, pszBuf, cbBuf, &cbActual); /* Release the module in any case. */ RTDbgModRelease(hMod); } else { /* * For the record based kernel versions we have a last resort heuristic which doesn't * require any symbols, try that here. */ if (!dbgDiggerLinuxLogBufferIsAsciiBuffer(pData, pUVM)) { RTGCPTR GCPtrLogBuf = 0; uint32_t cbLogBuf = 0; rc = dbgDiggerLinuxKrnlLogBufFindByNeedle(pData, pUVM, &GCPtrLogBuf, &cbLogBuf); if (RT_SUCCESS(rc)) rc = dbgDiggerLinuxKrnLogBufferProcess(pData, pUVM, GCPtrLogBuf, cbLogBuf, 0 /*idxFirst*/, 0 /*idxNext*/, fFlags, cMessages, pszBuf, cbBuf, &cbActual); } else rc = VERR_NOT_FOUND; } if (RT_FAILURE(rc) && rc != VERR_BUFFER_OVERFLOW) return rc; if (pcbActual) *pcbActual = cbActual; /* * All VBox strings are UTF-8 and bad things may in theory happen if we * pass bad UTF-8 to code which assumes it's all valid. So, we enforce * UTF-8 upon the guest kernel messages here even if they (probably) have * no defined code set in reality. */ if ( RT_SUCCESS(rc) && cbActual <= cbBuf) { pszBuf[cbActual - 1] = '\0'; RTStrPurgeEncoding(pszBuf); return VINF_SUCCESS; } if (cbBuf) { pszBuf[cbBuf - 1] = '\0'; RTStrPurgeEncoding(pszBuf); } return VERR_BUFFER_OVERFLOW; } /** * Worker destroying the config database. */ static DECLCALLBACK(int) dbgDiggerLinuxCfgDbDestroyWorker(PRTSTRSPACECORE pStr, void *pvUser) { PDBGDIGGERLINUXCFGITEM pCfgItem = (PDBGDIGGERLINUXCFGITEM)pStr; RTStrFree((char *)pCfgItem->Core.pszString); RTMemFree(pCfgItem); NOREF(pvUser); return 0; } /** * Destroy the config database. * * @returns nothing. * @param pThis The Linux digger data. */ static void dbgDiggerLinuxCfgDbDestroy(PDBGDIGGERLINUX pThis) { RTStrSpaceDestroy(&pThis->hCfgDb, dbgDiggerLinuxCfgDbDestroyWorker, NULL); } /** * @copydoc DBGFOSREG::pfnStackUnwindAssist */ static DECLCALLBACK(int) dbgDiggerLinuxStackUnwindAssist(PUVM pUVM, void *pvData, VMCPUID idCpu, PDBGFSTACKFRAME pFrame, PRTDBGUNWINDSTATE pState, PCCPUMCTX pInitialCtx, RTDBGAS hAs, uint64_t *puScratch) { RT_NOREF(pUVM, pvData, idCpu, pFrame, pState, pInitialCtx, hAs, puScratch); return VINF_SUCCESS; } /** * @copydoc DBGFOSREG::pfnQueryInterface */ static DECLCALLBACK(void *) dbgDiggerLinuxQueryInterface(PUVM pUVM, void *pvData, DBGFOSINTERFACE enmIf) { RT_NOREF1(pUVM); PDBGDIGGERLINUX pThis = (PDBGDIGGERLINUX)pvData; switch (enmIf) { case DBGFOSINTERFACE_DMESG: return &pThis->IDmesg; default: return NULL; } } /** * @copydoc DBGFOSREG::pfnQueryVersion */ static DECLCALLBACK(int) dbgDiggerLinuxQueryVersion(PUVM pUVM, void *pvData, char *pszVersion, size_t cchVersion) { PDBGDIGGERLINUX pThis = (PDBGDIGGERLINUX)pvData; Assert(pThis->fValid); /* * It's all in the linux banner. */ int rc = DBGFR3MemReadString(pUVM, 0, &pThis->AddrLinuxBanner, pszVersion, cchVersion); if (RT_SUCCESS(rc)) { char *pszEnd = RTStrEnd(pszVersion, cchVersion); AssertReturn(pszEnd, VERR_BUFFER_OVERFLOW); while ( pszEnd > pszVersion && RT_C_IS_SPACE(pszEnd[-1])) pszEnd--; *pszEnd = '\0'; } else RTStrPrintf(pszVersion, cchVersion, "DBGFR3MemRead -> %Rrc", rc); return rc; } /** * @copydoc DBGFOSREG::pfnTerm */ static DECLCALLBACK(void) dbgDiggerLinuxTerm(PUVM pUVM, void *pvData) { PDBGDIGGERLINUX pThis = (PDBGDIGGERLINUX)pvData; Assert(pThis->fValid); /* * Destroy configuration database. */ dbgDiggerLinuxCfgDbDestroy(pThis); /* * Unlink and release our modules. */ RTDBGAS hDbgAs = DBGFR3AsResolveAndRetain(pUVM, DBGF_AS_KERNEL); if (hDbgAs != NIL_RTDBGAS) { uint32_t iMod = RTDbgAsModuleCount(hDbgAs); while (iMod-- > 0) { RTDBGMOD hMod = RTDbgAsModuleByIndex(hDbgAs, iMod); if (hMod != NIL_RTDBGMOD) { if (RTDbgModGetTag(hMod) == DIG_LNX_MOD_TAG) { int rc = RTDbgAsModuleUnlink(hDbgAs, hMod); AssertRC(rc); } RTDbgModRelease(hMod); } } RTDbgAsRelease(hDbgAs); } pThis->fValid = false; } /** * @copydoc DBGFOSREG::pfnRefresh */ static DECLCALLBACK(int) dbgDiggerLinuxRefresh(PUVM pUVM, void *pvData) { PDBGDIGGERLINUX pThis = (PDBGDIGGERLINUX)pvData; NOREF(pThis); Assert(pThis->fValid); /* * For now we'll flush and reload everything. */ dbgDiggerLinuxTerm(pUVM, pvData); return dbgDiggerLinuxInit(pUVM, pvData); } /** * Worker for dbgDiggerLinuxFindStartOfNamesAndSymbolCount that update the * digger data. * * @returns VINF_SUCCESS. * @param pThis The Linux digger data to update. * @param pAddrKernelNames The kallsyms_names address. * @param cKernelSymbols The number of kernel symbol. * @param cbAddress The guest address size. */ static int dbgDiggerLinuxFoundStartOfNames(PDBGDIGGERLINUX pThis, PCDBGFADDRESS pAddrKernelNames, uint32_t cKernelSymbols, uint32_t cbAddress) { pThis->cKernelSymbols = cKernelSymbols; pThis->AddrKernelNames = *pAddrKernelNames; pThis->AddrKernelAddresses = *pAddrKernelNames; uint32_t cbSymbolsSkip = (pThis->fRelKrnlAddr ? 2 : 1) * cbAddress; /* Relative addressing introduces kallsyms_relative_base. */ uint32_t cbOffsets = pThis->fRelKrnlAddr ? sizeof(int32_t) : cbAddress; /* Offsets are always 32bits wide for relative addressing. */ uint32_t cbAlign = 0; /* * If the number of symbols is odd there is padding to align the following guest pointer * sized data properly on 64bit systems with relative addressing. */ if ( pThis->fRelKrnlAddr && pThis->f64Bit && (pThis->cKernelSymbols & 1)) cbAlign = sizeof(int32_t); DBGFR3AddrSub(&pThis->AddrKernelAddresses, cKernelSymbols * cbOffsets + cbSymbolsSkip + cbAlign); Log(("dbgDiggerLinuxFoundStartOfNames: AddrKernelAddresses=%RGv\n" "dbgDiggerLinuxFoundStartOfNames: cKernelSymbols=%#x (at %RGv)\n" "dbgDiggerLinuxFoundStartOfNames: AddrKernelName=%RGv\n", pThis->AddrKernelAddresses.FlatPtr, pThis->cKernelSymbols, pThis->AddrKernelNames.FlatPtr - cbAddress, pThis->AddrKernelNames.FlatPtr)); return VINF_SUCCESS; } /** * Tries to find the address of the kallsyms_names, kallsyms_num_syms and * kallsyms_addresses symbols. * * The kallsyms_num_syms is read and stored in pThis->cKernelSymbols, while the * addresses of the other two are stored as pThis->AddrKernelNames and * pThis->AddrKernelAddresses. * * @returns VBox status code, success indicating that all three variables have * been found and taken down. * @param pUVM The user mode VM handle. * @param pThis The Linux digger data. * @param pHitAddr An address we think is inside kallsyms_names. */ static int dbgDiggerLinuxFindStartOfNamesAndSymbolCount(PUVM pUVM, PDBGDIGGERLINUX pThis, PCDBGFADDRESS pHitAddr) { /* * Search backwards in chunks. */ union { uint8_t ab[0x1000]; uint32_t au32[0x1000 / sizeof(uint32_t)]; uint64_t au64[0x1000 / sizeof(uint64_t)]; } uBuf; uint32_t cbLeft = LNX_MAX_KALLSYMS_NAMES_SIZE; uint32_t cbBuf = pHitAddr->FlatPtr & (sizeof(uBuf) - 1); DBGFADDRESS CurAddr = *pHitAddr; DBGFR3AddrSub(&CurAddr, cbBuf); cbBuf += sizeof(uint64_t) - 1; /* In case our kobj hit is in the first 4/8 bytes. */ for (;;) { int rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, &CurAddr, &uBuf, sizeof(uBuf)); if (RT_FAILURE(rc)) return rc; /* * Since Linux 4.6 there are two different methods to store the kallsyms addresses * in the image. * * The first and longer existing method is to store the absolute addresses in an * array starting at kallsyms_addresses followed by a field which stores the number * of kernel symbols called kallsyms_num_syms. * The newer method is to use offsets stored in kallsyms_offsets and have a base pointer * to relate the offsets to called kallsyms_relative_base. One entry in kallsyms_offsets is * always 32bit wide regardless of the guest pointer size (this halves the table on 64bit * systems) but means more work for us for the 64bit case. * * When absolute addresses are used the following assumptions hold: * * We assume that the three symbols are aligned on guest pointer boundary. * * The boundary between the two tables should be noticable as the number * is unlikely to be more than 16 millions, there will be at least one zero * byte where it is, 64-bit will have 5 zero bytes. Zero bytes aren't all * that common in the kallsyms_names table. * * Also the kallsyms_names table starts with a length byte, which means * we're likely to see a byte in the range 1..31. * * The kallsyms_addresses are mostly sorted (except for the start where the * absolute symbols are), so we'll spot a bunch of kernel addresses * immediately preceeding the kallsyms_num_syms field. * * Lazy bird: If kallsyms_num_syms is on a buffer boundrary, we skip * the check for kernel addresses preceeding it. * * For relative offsets most of the assumptions from above are true too * except that we have to distinguish between the relative base address and the offsets. * Every observed kernel has a valid kernel address fo the relative base and kallsyms_relative_base * always comes before kallsyms_num_syms and is aligned on a guest pointer boundary. * Offsets are stored before kallsyms_relative_base and don't contain valid kernel addresses. * * To distinguish between absolute and relative offsetting we check the data before a candidate * for kallsyms_num_syms. If all entries before the kallsyms_num_syms candidate are valid kernel * addresses absolute addresses are assumed. If this is not the case but the first entry before * kallsyms_num_syms is a valid kernel address we check whether the data before and the possible * relative base form a valid kernel address and assume relative offsets. */ if (pThis->f64Bit) { uint32_t i = cbBuf / sizeof(uint64_t) - 1; while (i-- > 0) if ( uBuf.au64[i] <= LNX_MAX_KALLSYMS_SYMBOLS && uBuf.au64[i] >= LNX_MIN_KALLSYMS_SYMBOLS) { uint8_t *pb = (uint8_t *)&uBuf.au64[i + 1]; if ( pb[0] <= LNX_MAX_KALLSYMS_ENC_LENGTH && pb[0] >= LNX_MIN_KALLSYMS_ENC_LENGTH) { /* * Check whether we have a valid kernel address and try to distinguish * whether the kernel uses relative offsetting or absolute addresses. */ if ( (i >= 1 && LNX64_VALID_ADDRESS(uBuf.au64[i - 1])) && (i >= 2 && !LNX64_VALID_ADDRESS(uBuf.au64[i - 2])) && (i >= 3 && !LNX64_VALID_ADDRESS(uBuf.au64[i - 3]))) { RTGCUINTPTR uKrnlRelBase = uBuf.au64[i - 1]; DBGFADDRESS RelAddr = CurAddr; int32_t aiRelOff[3]; rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, DBGFR3AddrAdd(&RelAddr, (i - 1) * sizeof(uint64_t) - sizeof(aiRelOff)), &aiRelOff[0], sizeof(aiRelOff)); if ( RT_SUCCESS(rc) && LNX64_VALID_ADDRESS(uKrnlRelBase + aiRelOff[0]) && LNX64_VALID_ADDRESS(uKrnlRelBase + aiRelOff[1]) && LNX64_VALID_ADDRESS(uKrnlRelBase + aiRelOff[2])) { Log(("dbgDiggerLinuxFindStartOfNamesAndSymbolCount: relative base %RGv (at %RGv)\n", uKrnlRelBase, CurAddr.FlatPtr + (i - 1) * sizeof(uint64_t))); pThis->fRelKrnlAddr = true; pThis->uKernelRelativeBase = uKrnlRelBase; return dbgDiggerLinuxFoundStartOfNames(pThis, DBGFR3AddrAdd(&CurAddr, (i + 1) * sizeof(uint64_t)), (uint32_t)uBuf.au64[i], sizeof(uint64_t)); } } if ( (i <= 0 || LNX64_VALID_ADDRESS(uBuf.au64[i - 1])) && (i <= 1 || LNX64_VALID_ADDRESS(uBuf.au64[i - 2])) && (i <= 2 || LNX64_VALID_ADDRESS(uBuf.au64[i - 3]))) return dbgDiggerLinuxFoundStartOfNames(pThis, DBGFR3AddrAdd(&CurAddr, (i + 1) * sizeof(uint64_t)), (uint32_t)uBuf.au64[i], sizeof(uint64_t)); } } } else { uint32_t i = cbBuf / sizeof(uint32_t) - 1; while (i-- > 0) if ( uBuf.au32[i] <= LNX_MAX_KALLSYMS_SYMBOLS && uBuf.au32[i] >= LNX_MIN_KALLSYMS_SYMBOLS) { uint8_t *pb = (uint8_t *)&uBuf.au32[i + 1]; if ( pb[0] <= LNX_MAX_KALLSYMS_ENC_LENGTH && pb[0] >= LNX_MIN_KALLSYMS_ENC_LENGTH) { /* Check for relative base addressing. */ if (i >= 1 && LNX32_VALID_ADDRESS(uBuf.au32[i - 1])) { RTGCUINTPTR uKrnlRelBase = uBuf.au32[i - 1]; if ( (i <= 1 || LNX32_VALID_ADDRESS(uKrnlRelBase + uBuf.au32[i - 2])) && (i <= 2 || LNX32_VALID_ADDRESS(uKrnlRelBase + uBuf.au32[i - 3]))) { Log(("dbgDiggerLinuxFindStartOfNamesAndSymbolCount: relative base %RGv (at %RGv)\n", uKrnlRelBase, CurAddr.FlatPtr + (i - 1) * sizeof(uint32_t))); pThis->fRelKrnlAddr = true; pThis->uKernelRelativeBase = uKrnlRelBase; return dbgDiggerLinuxFoundStartOfNames(pThis, DBGFR3AddrAdd(&CurAddr, (i + 1) * sizeof(uint32_t)), uBuf.au32[i], sizeof(uint32_t)); } } if ( (i <= 0 || LNX32_VALID_ADDRESS(uBuf.au32[i - 1])) && (i <= 1 || LNX32_VALID_ADDRESS(uBuf.au32[i - 2])) && (i <= 2 || LNX32_VALID_ADDRESS(uBuf.au32[i - 3]))) return dbgDiggerLinuxFoundStartOfNames(pThis, DBGFR3AddrAdd(&CurAddr, (i + 1) * sizeof(uint32_t)), uBuf.au32[i], sizeof(uint32_t)); } } } /* * Advance */ if (RT_UNLIKELY(cbLeft <= sizeof(uBuf))) { Log(("dbgDiggerLinuxFindStartOfNamesAndSymbolCount: failed (pHitAddr=%RGv)\n", pHitAddr->FlatPtr)); return VERR_NOT_FOUND; } cbLeft -= sizeof(uBuf); DBGFR3AddrSub(&CurAddr, sizeof(uBuf)); cbBuf = sizeof(uBuf); } } /** * Worker for dbgDiggerLinuxFindEndNames that records the findings. * * @returns VINF_SUCCESS * @param pThis The linux digger data to update. * @param pAddrMarkers The address of the marker (kallsyms_markers). * @param cbMarkerEntry The size of a marker entry (32-bit or 64-bit). */ static int dbgDiggerLinuxFoundMarkers(PDBGDIGGERLINUX pThis, PCDBGFADDRESS pAddrMarkers, uint32_t cbMarkerEntry) { pThis->cbKernelNames = pAddrMarkers->FlatPtr - pThis->AddrKernelNames.FlatPtr; pThis->AddrKernelNameMarkers = *pAddrMarkers; pThis->cKernelNameMarkers = RT_ALIGN_32(pThis->cKernelSymbols, 256) / 256; pThis->AddrKernelTokenTable = *pAddrMarkers; DBGFR3AddrAdd(&pThis->AddrKernelTokenTable, pThis->cKernelNameMarkers * cbMarkerEntry); Log(("dbgDiggerLinuxFoundMarkers: AddrKernelNames=%RGv cbKernelNames=%#x\n" "dbgDiggerLinuxFoundMarkers: AddrKernelNameMarkers=%RGv cKernelNameMarkers=%#x\n" "dbgDiggerLinuxFoundMarkers: AddrKernelTokenTable=%RGv\n", pThis->AddrKernelNames.FlatPtr, pThis->cbKernelNames, pThis->AddrKernelNameMarkers.FlatPtr, pThis->cKernelNameMarkers, pThis->AddrKernelTokenTable.FlatPtr)); return VINF_SUCCESS; } /** * Tries to find the end of kallsyms_names and thereby the start of * kallsyms_markers and kallsyms_token_table. * * The kallsyms_names size is stored in pThis->cbKernelNames, the addresses of * the two other symbols in pThis->AddrKernelNameMarkers and * pThis->AddrKernelTokenTable. The number of marker entries is stored in * pThis->cKernelNameMarkers. * * @returns VBox status code, success indicating that all three variables have * been found and taken down. * @param pUVM The user mode VM handle. * @param pThis The Linux digger data. * @param pHitAddr An address we think is inside kallsyms_names. */ static int dbgDiggerLinuxFindEndOfNamesAndMore(PUVM pUVM, PDBGDIGGERLINUX pThis, PCDBGFADDRESS pHitAddr) { /* * Search forward in chunks. */ union { uint8_t ab[0x1000]; uint32_t au32[0x1000 / sizeof(uint32_t)]; uint64_t au64[0x1000 / sizeof(uint64_t)]; } uBuf; bool fPendingZeroHit = false; uint32_t cbLeft = LNX_MAX_KALLSYMS_NAMES_SIZE + sizeof(uBuf); uint32_t offBuf = pHitAddr->FlatPtr & (sizeof(uBuf) - 1); DBGFADDRESS CurAddr = *pHitAddr; DBGFR3AddrSub(&CurAddr, offBuf); for (;;) { int rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, &CurAddr, &uBuf, sizeof(uBuf)); if (RT_FAILURE(rc)) return rc; /* * The kallsyms_names table is followed by kallsyms_markers we assume, * using sizeof(unsigned long) alignment like the preceeding symbols. * * The kallsyms_markers table has entried sizeof(unsigned long) and * contains offsets into kallsyms_names. The kallsyms_markers used to * index kallsyms_names and reduce seek time when looking up the name * of an address/symbol. Each entry in kallsyms_markers covers 256 * symbol names. * * Because of this, the first entry is always zero and all the entries * are ascending. It also follows that the size of the table can be * calculated from kallsyms_num_syms. * * Note! We could also have walked kallsyms_names by skipping * kallsyms_num_syms names, but this is faster and we will * validate the encoded names later. */ if (pThis->f64Bit) { if ( RT_UNLIKELY(fPendingZeroHit) && uBuf.au64[0] >= (LNX_MIN_KALLSYMS_ENC_LENGTH + 1) * 256 && uBuf.au64[0] <= (LNX_MAX_KALLSYMS_ENC_LENGTH + 1) * 256) return dbgDiggerLinuxFoundMarkers(pThis, DBGFR3AddrSub(&CurAddr, sizeof(uint64_t)), sizeof(uint64_t)); uint32_t const cEntries = sizeof(uBuf) / sizeof(uint64_t); for (uint32_t i = offBuf / sizeof(uint64_t); i < cEntries; i++) if (uBuf.au64[i] == 0) { if (RT_UNLIKELY(i + 1 >= cEntries)) { fPendingZeroHit = true; break; } if ( uBuf.au64[i + 1] >= (LNX_MIN_KALLSYMS_ENC_LENGTH + 1) * 256 && uBuf.au64[i + 1] <= (LNX_MAX_KALLSYMS_ENC_LENGTH + 1) * 256) return dbgDiggerLinuxFoundMarkers(pThis, DBGFR3AddrAdd(&CurAddr, i * sizeof(uint64_t)), sizeof(uint64_t)); } } else { if ( RT_UNLIKELY(fPendingZeroHit) && uBuf.au32[0] >= (LNX_MIN_KALLSYMS_ENC_LENGTH + 1) * 256 && uBuf.au32[0] <= (LNX_MAX_KALLSYMS_ENC_LENGTH + 1) * 256) return dbgDiggerLinuxFoundMarkers(pThis, DBGFR3AddrSub(&CurAddr, sizeof(uint32_t)), sizeof(uint32_t)); uint32_t const cEntries = sizeof(uBuf) / sizeof(uint32_t); for (uint32_t i = offBuf / sizeof(uint32_t); i < cEntries; i++) if (uBuf.au32[i] == 0) { if (RT_UNLIKELY(i + 1 >= cEntries)) { fPendingZeroHit = true; break; } if ( uBuf.au32[i + 1] >= (LNX_MIN_KALLSYMS_ENC_LENGTH + 1) * 256 && uBuf.au32[i + 1] <= (LNX_MAX_KALLSYMS_ENC_LENGTH + 1) * 256) return dbgDiggerLinuxFoundMarkers(pThis, DBGFR3AddrAdd(&CurAddr, i * sizeof(uint32_t)), sizeof(uint32_t)); } } /* * Advance */ if (RT_UNLIKELY(cbLeft <= sizeof(uBuf))) { Log(("dbgDiggerLinuxFindEndOfNamesAndMore: failed (pHitAddr=%RGv)\n", pHitAddr->FlatPtr)); return VERR_NOT_FOUND; } cbLeft -= sizeof(uBuf); DBGFR3AddrAdd(&CurAddr, sizeof(uBuf)); offBuf = 0; } } /** * Locates the kallsyms_token_index table. * * Storing the address in pThis->AddrKernelTokenIndex and the size of the token * table in pThis->cbKernelTokenTable. * * @returns VBox status code. * @param pUVM The user mode VM handle. * @param pThis The Linux digger data. */ static int dbgDiggerLinuxFindTokenIndex(PUVM pUVM, PDBGDIGGERLINUX pThis) { /* * The kallsyms_token_table is very much like a string table. Due to the * nature of the compression algorithm it is reasonably short (one example * here is 853 bytes), so we'll not be reading it in chunks but in full. * To be on the safe side, we read 8KB, ASSUMING we won't run into unmapped * memory or any other nasty stuff... */ union { uint8_t ab[0x2000]; uint16_t au16[0x2000 / sizeof(uint16_t)]; } uBuf; DBGFADDRESS CurAddr = pThis->AddrKernelTokenTable; int rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, &CurAddr, &uBuf, sizeof(uBuf)); if (RT_FAILURE(rc)) return rc; /* * We've got two choices here, either walk the string table or look for * the next structure, kallsyms_token_index. * * The token index is a table of 256 uint16_t entries (index by bytes * from kallsyms_names) that gives offsets in kallsyms_token_table. It * starts with a zero entry and the following entries are sorted in * ascending order. The range of the entries are reasonably small since * kallsyms_token_table is small. * * The alignment seems to be sizeof(unsigned long), just like * kallsyms_token_table. * * So, we start by looking for a zero 16-bit entry. */ uint32_t cIncr = (pThis->f64Bit ? sizeof(uint64_t) : sizeof(uint32_t)) / sizeof(uint16_t); for (uint32_t i = 0; i < sizeof(uBuf) / sizeof(uint16_t) - 16; i += cIncr) if ( uBuf.au16[i] == 0 && uBuf.au16[i + 1] > 0 && uBuf.au16[i + 1] <= LNX_MAX_KALLSYMS_TOKEN_LEN && (uint16_t)(uBuf.au16[i + 2] - uBuf.au16[i + 1] - 1U) <= (uint16_t)LNX_MAX_KALLSYMS_TOKEN_LEN && (uint16_t)(uBuf.au16[i + 3] - uBuf.au16[i + 2] - 1U) <= (uint16_t)LNX_MAX_KALLSYMS_TOKEN_LEN && (uint16_t)(uBuf.au16[i + 4] - uBuf.au16[i + 3] - 1U) <= (uint16_t)LNX_MAX_KALLSYMS_TOKEN_LEN && (uint16_t)(uBuf.au16[i + 5] - uBuf.au16[i + 4] - 1U) <= (uint16_t)LNX_MAX_KALLSYMS_TOKEN_LEN && (uint16_t)(uBuf.au16[i + 6] - uBuf.au16[i + 5] - 1U) <= (uint16_t)LNX_MAX_KALLSYMS_TOKEN_LEN ) { pThis->AddrKernelTokenIndex = CurAddr; DBGFR3AddrAdd(&pThis->AddrKernelTokenIndex, i * sizeof(uint16_t)); pThis->cbKernelTokenTable = i * sizeof(uint16_t); return VINF_SUCCESS; } Log(("dbgDiggerLinuxFindTokenIndex: Failed (%RGv..%RGv)\n", CurAddr.FlatPtr, CurAddr.FlatPtr + (RTGCUINTPTR)sizeof(uBuf))); return VERR_NOT_FOUND; } /** * Loads the kernel symbols from the given kallsyms offset table decoding the symbol names * (worker common for dbgDiggerLinuxLoadKernelSymbolsAbsolute() and dbgDiggerLinuxLoadKernelSymbolsRelative()). * * @returns VBox status code. * @param pUVM The user mode VM handle. * @param pThis The Linux digger data. * @param uKernelStart Flat kernel start address. * @param cbKernel Size of the kernel in bytes. * @param pauSymOff Pointer to the array of symbol offsets in the kallsyms table * relative to the start of the kernel. */ static int dbgDiggerLinuxLoadKernelSymbolsWorker(PUVM pUVM, PDBGDIGGERLINUX pThis, RTGCUINTPTR uKernelStart, RTGCUINTPTR cbKernel, RTGCUINTPTR *pauSymOff) { uint8_t *pbNames = (uint8_t *)RTMemAllocZ(pThis->cbKernelNames); int rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, &pThis->AddrKernelNames, pbNames, pThis->cbKernelNames); if (RT_SUCCESS(rc)) { char *pszzTokens = (char *)RTMemAllocZ(pThis->cbKernelTokenTable); rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, &pThis->AddrKernelTokenTable, pszzTokens, pThis->cbKernelTokenTable); if (RT_SUCCESS(rc)) { uint16_t *paoffTokens = (uint16_t *)RTMemAllocZ(256 * sizeof(uint16_t)); rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, &pThis->AddrKernelTokenIndex, paoffTokens, 256 * sizeof(uint16_t)); if (RT_SUCCESS(rc)) { /* * Create a module for the kernel. */ RTDBGMOD hMod; rc = RTDbgModCreate(&hMod, "vmlinux", cbKernel, 0 /*fFlags*/); if (RT_SUCCESS(rc)) { rc = RTDbgModSetTag(hMod, DIG_LNX_MOD_TAG); AssertRC(rc); rc = VINF_SUCCESS; /* * Enumerate the symbols. */ uint32_t offName = 0; uint32_t cLeft = pThis->cKernelSymbols; while (cLeft-- > 0 && RT_SUCCESS(rc)) { /* Decode the symbol name first. */ if (RT_LIKELY(offName < pThis->cbKernelNames)) { uint8_t cbName = pbNames[offName++]; if (RT_LIKELY(offName + cbName <= pThis->cbKernelNames)) { char szSymbol[4096]; uint32_t offSymbol = 0; while (cbName-- > 0) { uint8_t bEnc = pbNames[offName++]; uint16_t offToken = paoffTokens[bEnc]; if (RT_LIKELY(offToken < pThis->cbKernelTokenTable)) { const char *pszToken = &pszzTokens[offToken]; char ch; while ((ch = *pszToken++) != '\0') if (offSymbol < sizeof(szSymbol) - 1) szSymbol[offSymbol++] = ch; } else { rc = VERR_INVALID_UTF8_ENCODING; break; } } szSymbol[offSymbol < sizeof(szSymbol) ? offSymbol : sizeof(szSymbol) - 1] = '\0'; /* The offset. */ RTGCUINTPTR uSymOff = *pauSymOff; pauSymOff++; /* Add it without the type char. */ if (uSymOff <= cbKernel) { rc = RTDbgModSymbolAdd(hMod, &szSymbol[1], RTDBGSEGIDX_RVA, uSymOff, 0 /*cb*/, 0 /*fFlags*/, NULL); if (RT_FAILURE(rc)) { if ( rc == VERR_DBG_SYMBOL_NAME_OUT_OF_RANGE || rc == VERR_DBG_INVALID_RVA || rc == VERR_DBG_ADDRESS_CONFLICT || rc == VERR_DBG_DUPLICATE_SYMBOL) { Log2(("dbgDiggerLinuxLoadKernelSymbols: RTDbgModSymbolAdd(,%s,) failed %Rrc (ignored)\n", szSymbol, rc)); rc = VINF_SUCCESS; } else Log(("dbgDiggerLinuxLoadKernelSymbols: RTDbgModSymbolAdd(,%s,) failed %Rrc\n", szSymbol, rc)); } } } else { rc = VERR_END_OF_STRING; Log(("dbgDiggerLinuxLoadKernelSymbols: offName=%#x cLeft=%#x cbName=%#x cbKernelNames=%#x\n", offName, cLeft, cbName, pThis->cbKernelNames)); } } else { rc = VERR_END_OF_STRING; Log(("dbgDiggerLinuxLoadKernelSymbols: offName=%#x cLeft=%#x cbKernelNames=%#x\n", offName, cLeft, pThis->cbKernelNames)); } } /* * Link the module into the address space. */ if (RT_SUCCESS(rc)) { RTDBGAS hAs = DBGFR3AsResolveAndRetain(pUVM, DBGF_AS_KERNEL); if (hAs != NIL_RTDBGAS) rc = RTDbgAsModuleLink(hAs, hMod, uKernelStart, RTDBGASLINK_FLAGS_REPLACE); else rc = VERR_INTERNAL_ERROR; RTDbgAsRelease(hAs); } else Log(("dbgDiggerLinuxLoadKernelSymbols: Failed: %Rrc\n", rc)); RTDbgModRelease(hMod); } else Log(("dbgDiggerLinuxLoadKernelSymbols: RTDbgModCreate failed: %Rrc\n", rc)); } else Log(("dbgDiggerLinuxLoadKernelSymbols: Reading token index at %RGv failed: %Rrc\n", pThis->AddrKernelTokenIndex.FlatPtr, rc)); RTMemFree(paoffTokens); } else Log(("dbgDiggerLinuxLoadKernelSymbols: Reading token table at %RGv failed: %Rrc\n", pThis->AddrKernelTokenTable.FlatPtr, rc)); RTMemFree(pszzTokens); } else Log(("dbgDiggerLinuxLoadKernelSymbols: Reading encoded names at %RGv failed: %Rrc\n", pThis->AddrKernelNames.FlatPtr, rc)); RTMemFree(pbNames); return rc; } /** * Loads the kernel symbols from the kallsyms table if it contains absolute addresses * * @returns VBox status code. * @param pUVM The user mode VM handle. * @param pThis The Linux digger data. */ static int dbgDiggerLinuxLoadKernelSymbolsAbsolute(PUVM pUVM, PDBGDIGGERLINUX pThis) { /* * Allocate memory for temporary table copies, reading the tables as we go. */ uint32_t const cbGuestAddr = pThis->f64Bit ? sizeof(uint64_t) : sizeof(uint32_t); void *pvAddresses = RTMemAllocZ(pThis->cKernelSymbols * cbGuestAddr); int rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, &pThis->AddrKernelAddresses, pvAddresses, pThis->cKernelSymbols * cbGuestAddr); if (RT_SUCCESS(rc)) { /* * Figure out the kernel start and end and convert the absolute addresses to relative offsets. */ RTGCUINTPTR uKernelStart = pThis->AddrKernelAddresses.FlatPtr; RTGCUINTPTR uKernelEnd = pThis->AddrKernelTokenIndex.FlatPtr + 256 * sizeof(uint16_t); RTGCUINTPTR *pauSymOff = (RTGCUINTPTR *)RTMemTmpAllocZ(pThis->cKernelSymbols * sizeof(RTGCUINTPTR)); uint32_t i; if (cbGuestAddr == sizeof(uint64_t)) { uint64_t *pauAddrs = (uint64_t *)pvAddresses; for (i = 0; i < pThis->cKernelSymbols; i++) if ( pauAddrs[i] < uKernelStart && LNX64_VALID_ADDRESS(pauAddrs[i]) && uKernelStart - pauAddrs[i] < LNX_MAX_KERNEL_SIZE) uKernelStart = pauAddrs[i]; for (i = pThis->cKernelSymbols - 1; i > 0; i--) if ( pauAddrs[i] > uKernelEnd && LNX64_VALID_ADDRESS(pauAddrs[i]) && pauAddrs[i] - uKernelEnd < LNX_MAX_KERNEL_SIZE) uKernelEnd = pauAddrs[i]; for (i = 0; i < pThis->cKernelSymbols; i++) pauSymOff[i] = pauAddrs[i] - uKernelStart; } else { uint32_t *pauAddrs = (uint32_t *)pvAddresses; for (i = 0; i < pThis->cKernelSymbols; i++) if ( pauAddrs[i] < uKernelStart && LNX32_VALID_ADDRESS(pauAddrs[i]) && uKernelStart - pauAddrs[i] < LNX_MAX_KERNEL_SIZE) uKernelStart = pauAddrs[i]; for (i = pThis->cKernelSymbols - 1; i > 0; i--) if ( pauAddrs[i] > uKernelEnd && LNX32_VALID_ADDRESS(pauAddrs[i]) && pauAddrs[i] - uKernelEnd < LNX_MAX_KERNEL_SIZE) uKernelEnd = pauAddrs[i]; for (i = 0; i < pThis->cKernelSymbols; i++) pauSymOff[i] = pauAddrs[i] - uKernelStart; } RTGCUINTPTR cbKernel = uKernelEnd - uKernelStart; pThis->cbKernel = (uint32_t)cbKernel; DBGFR3AddrFromFlat(pUVM, &pThis->AddrKernelBase, uKernelStart); Log(("dbgDiggerLinuxLoadKernelSymbolsAbsolute: uKernelStart=%RGv cbKernel=%#x\n", uKernelStart, cbKernel)); rc = dbgDiggerLinuxLoadKernelSymbolsWorker(pUVM, pThis, uKernelStart, cbKernel, pauSymOff); if (RT_FAILURE(rc)) Log(("dbgDiggerLinuxLoadKernelSymbolsAbsolute: Loading symbols from given offset table failed: %Rrc\n", rc)); RTMemTmpFree(pauSymOff); } else Log(("dbgDiggerLinuxLoadKernelSymbolsAbsolute: Reading symbol addresses at %RGv failed: %Rrc\n", pThis->AddrKernelAddresses.FlatPtr, rc)); RTMemFree(pvAddresses); return rc; } /** * Loads the kernel symbols from the kallsyms table if it contains absolute addresses * * @returns VBox status code. * @param pUVM The user mode VM handle. * @param pThis The Linux digger data. */ static int dbgDiggerLinuxLoadKernelSymbolsRelative(PUVM pUVM, PDBGDIGGERLINUX pThis) { /* * Allocate memory for temporary table copies, reading the tables as we go. */ int32_t *pai32Offsets = (int32_t *)RTMemAllocZ(pThis->cKernelSymbols * sizeof(int32_t)); int rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, &pThis->AddrKernelAddresses, pai32Offsets, pThis->cKernelSymbols * sizeof(int32_t)); if (RT_SUCCESS(rc)) { /* * Figure out the kernel start and end and convert the absolute addresses to relative offsets. */ RTGCUINTPTR uKernelStart = pThis->AddrKernelAddresses.FlatPtr; RTGCUINTPTR uKernelEnd = pThis->AddrKernelTokenIndex.FlatPtr + 256 * sizeof(uint16_t); RTGCUINTPTR *pauSymOff = (RTGCUINTPTR *)RTMemTmpAllocZ(pThis->cKernelSymbols * sizeof(RTGCUINTPTR)); uint32_t i; for (i = 0; i < pThis->cKernelSymbols; i++) { RTGCUINTPTR uSymAddr = dbgDiggerLinuxConvOffsetToAddr(pThis, pai32Offsets[i]); if ( uSymAddr < uKernelStart && (pThis->f64Bit ? LNX64_VALID_ADDRESS(uSymAddr) : LNX32_VALID_ADDRESS(uSymAddr)) && uKernelStart - uSymAddr < LNX_MAX_KERNEL_SIZE) uKernelStart = uSymAddr; } for (i = pThis->cKernelSymbols - 1; i > 0; i--) { RTGCUINTPTR uSymAddr = dbgDiggerLinuxConvOffsetToAddr(pThis, pai32Offsets[i]); if ( uSymAddr > uKernelEnd && (pThis->f64Bit ? LNX64_VALID_ADDRESS(uSymAddr) : LNX32_VALID_ADDRESS(uSymAddr)) && uSymAddr - uKernelEnd < LNX_MAX_KERNEL_SIZE) uKernelEnd = uSymAddr; /* Store the offset from the derived kernel start address. */ pauSymOff[i] = uSymAddr - uKernelStart; } RTGCUINTPTR cbKernel = uKernelEnd - uKernelStart; pThis->cbKernel = (uint32_t)cbKernel; DBGFR3AddrFromFlat(pUVM, &pThis->AddrKernelBase, uKernelStart); Log(("dbgDiggerLinuxLoadKernelSymbolsRelative: uKernelStart=%RGv cbKernel=%#x\n", uKernelStart, cbKernel)); rc = dbgDiggerLinuxLoadKernelSymbolsWorker(pUVM, pThis, uKernelStart, cbKernel, pauSymOff); if (RT_FAILURE(rc)) Log(("dbgDiggerLinuxLoadKernelSymbolsRelative: Loading symbols from given offset table failed: %Rrc\n", rc)); RTMemTmpFree(pauSymOff); } else Log(("dbgDiggerLinuxLoadKernelSymbolsRelative: Reading symbol addresses at %RGv failed: %Rrc\n", pThis->AddrKernelAddresses.FlatPtr, rc)); RTMemFree(pai32Offsets); return rc; } /** * Loads the kernel symbols. * * @returns VBox status code. * @param pUVM The user mode VM handle. * @param pThis The Linux digger data. */ static int dbgDiggerLinuxLoadKernelSymbols(PUVM pUVM, PDBGDIGGERLINUX pThis) { /* * First the kernel itself. */ if (pThis->fRelKrnlAddr) return dbgDiggerLinuxLoadKernelSymbolsRelative(pUVM, pThis); return dbgDiggerLinuxLoadKernelSymbolsAbsolute(pUVM, pThis); } /* * The module structure changed it was easier to produce different code for * each version of the structure. The C preprocessor rules! */ #define LNX_TEMPLATE_HEADER "DBGPlugInLinuxModuleCodeTmpl.cpp.h" #define LNX_BIT_SUFFIX _amd64 #define LNX_PTR_T uint64_t #define LNX_64BIT 1 #include "DBGPlugInLinuxModuleVerTmpl.cpp.h" #define LNX_BIT_SUFFIX _x86 #define LNX_PTR_T uint32_t #define LNX_64BIT 0 #include "DBGPlugInLinuxModuleVerTmpl.cpp.h" #undef LNX_TEMPLATE_HEADER static const struct { uint32_t uVersion; bool f64Bit; uint64_t (*pfnProcessModule)(PDBGDIGGERLINUX pThis, PUVM pUVM, PDBGFADDRESS pAddrModule); } g_aModVersions[] = { #define LNX_TEMPLATE_HEADER "DBGPlugInLinuxModuleTableEntryTmpl.cpp.h" #define LNX_BIT_SUFFIX _amd64 #define LNX_64BIT 1 #include "DBGPlugInLinuxModuleVerTmpl.cpp.h" #define LNX_BIT_SUFFIX _x86 #define LNX_64BIT 0 #include "DBGPlugInLinuxModuleVerTmpl.cpp.h" #undef LNX_TEMPLATE_HEADER }; /** * Tries to find and process the module list. * * @returns VBox status code. * @param pThis The Linux digger data. * @param pUVM The user mode VM handle. */ static int dbgDiggerLinuxLoadModules(PDBGDIGGERLINUX pThis, PUVM pUVM) { /* * Locate the list head. */ RTDBGAS hAs = DBGFR3AsResolveAndRetain(pUVM, DBGF_AS_KERNEL); RTDBGSYMBOL SymInfo; int rc = RTDbgAsSymbolByName(hAs, "vmlinux!modules", &SymInfo, NULL); RTDbgAsRelease(hAs); if (RT_FAILURE(rc)) return VERR_NOT_FOUND; if (RT_FAILURE(rc)) { LogRel(("dbgDiggerLinuxLoadModules: Failed to locate the module list (%Rrc).\n", rc)); return VERR_NOT_FOUND; } /* * Read the list anchor. */ union { uint32_t volatile u32Pair[2]; uint64_t u64Pair[2]; } uListAnchor; DBGFADDRESS Addr; rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, DBGFR3AddrFromFlat(pUVM, &Addr, SymInfo.Value), &uListAnchor, pThis->f64Bit ? sizeof(uListAnchor.u64Pair) : sizeof(uListAnchor.u32Pair)); if (RT_FAILURE(rc)) { LogRel(("dbgDiggerLinuxLoadModules: Error reading list anchor at %RX64: %Rrc\n", SymInfo.Value, rc)); return VERR_NOT_FOUND; } if (!pThis->f64Bit) { uListAnchor.u64Pair[1] = uListAnchor.u32Pair[1]; ASMCompilerBarrier(); uListAnchor.u64Pair[0] = uListAnchor.u32Pair[0]; } /* * Get a numerical version number. */ char szVersion[256] = "Linux version 4.19.0"; bool fValid = pThis->fValid; pThis->fValid = true; dbgDiggerLinuxQueryVersion(pUVM, pThis, szVersion, sizeof(szVersion)); pThis->fValid = fValid; const char *pszVersion = szVersion; while (*pszVersion && !RT_C_IS_DIGIT(*pszVersion)) pszVersion++; size_t offVersion = 0; uint32_t uMajor = 0; while (pszVersion[offVersion] && RT_C_IS_DIGIT(pszVersion[offVersion])) uMajor = uMajor * 10 + pszVersion[offVersion++] - '0'; if (pszVersion[offVersion] == '.') offVersion++; uint32_t uMinor = 0; while (pszVersion[offVersion] && RT_C_IS_DIGIT(pszVersion[offVersion])) uMinor = uMinor * 10 + pszVersion[offVersion++] - '0'; if (pszVersion[offVersion] == '.') offVersion++; uint32_t uBuild = 0; while (pszVersion[offVersion] && RT_C_IS_DIGIT(pszVersion[offVersion])) uBuild = uBuild * 10 + pszVersion[offVersion++] - '0'; uint32_t const uGuestVer = LNX_MK_VER(uMajor, uMinor, uBuild); if (uGuestVer == 0) { LogRel(("dbgDiggerLinuxLoadModules: Failed to parse version string: %s\n", pszVersion)); return VERR_NOT_FOUND; } /* * Find the g_aModVersion entry that fits the best. * ASSUMES strict descending order by bitcount and version. */ Assert(g_aModVersions[0].f64Bit == true); unsigned i = 0; if (!pThis->f64Bit) while (i < RT_ELEMENTS(g_aModVersions) && g_aModVersions[i].f64Bit) i++; while ( i < RT_ELEMENTS(g_aModVersions) && g_aModVersions[i].f64Bit == pThis->f64Bit && uGuestVer < g_aModVersions[i].uVersion) i++; if (i >= RT_ELEMENTS(g_aModVersions)) { LogRel(("dbgDiggerLinuxLoadModules: Failed to find anything matching version: %u.%u.%u (%s)\n", uMajor, uMinor, uBuild, pszVersion)); return VERR_NOT_FOUND; } /* * Walk the list. */ uint64_t uModAddr = uListAnchor.u64Pair[0]; for (size_t iModule = 0; iModule < 4096 && uModAddr != SymInfo.Value && uModAddr != 0; iModule++) uModAddr = g_aModVersions[i].pfnProcessModule(pThis, pUVM, DBGFR3AddrFromFlat(pUVM, &Addr, uModAddr)); return VINF_SUCCESS; } /** * Checks if there is a likely kallsyms_names fragment at pHitAddr. * * @returns true if it's a likely fragment, false if not. * @param pUVM The user mode VM handle. * @param pHitAddr The address where paNeedle was found. * @param pabNeedle The fragment we've been searching for. * @param cbNeedle The length of the fragment. */ static bool dbgDiggerLinuxIsLikelyNameFragment(PUVM pUVM, PCDBGFADDRESS pHitAddr, uint8_t const *pabNeedle, uint8_t cbNeedle) { /* * Examples of lead and tail bytes of our choosen needle in a randomly * picked kernel: * k o b j * 22 6b 6f 62 6a aa * fc 6b 6f 62 6a aa * 82 6b 6f 62 6a 5f - ascii trail byte (_). * ee 6b 6f 62 6a aa * fc 6b 6f 62 6a 5f - ascii trail byte (_). * 0a 74 6b 6f 62 6a 5f ea - ascii lead (t) and trail (_) bytes. * 0b 54 6b 6f 62 6a aa - ascii lead byte (T). * ... omitting 29 samples similar to the last two ... * d8 6b 6f 62 6a aa * d8 6b 6f 62 6a aa * d8 6b 6f 62 6a aa * d8 6b 6f 62 6a aa * f9 5f 6b 6f 62 6a 5f 94 - ascii lead and trail bytes (_) * f9 5f 6b 6f 62 6a 0c - ascii lead byte (_). * fd 6b 6f 62 6a 0f * ... enough. */ uint8_t abBuf[32]; DBGFADDRESS ReadAddr = *pHitAddr; DBGFR3AddrSub(&ReadAddr, 2); int rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, &ReadAddr, abBuf, 2 + cbNeedle + 2); if (RT_SUCCESS(rc)) { if (memcmp(&abBuf[2], pabNeedle, cbNeedle) == 0) /* paranoia */ { uint8_t const bLead = abBuf[1] == '_' || abBuf[1] == 'T' || abBuf[1] == 't' ? abBuf[0] : abBuf[1]; uint8_t const offTail = 2 + cbNeedle; uint8_t const bTail = abBuf[offTail] == '_' ? abBuf[offTail] : abBuf[offTail + 1]; if ( bLead >= 1 && (bLead < 0x20 || bLead >= 0x80) && bTail >= 1 && (bTail < 0x20 || bTail >= 0x80)) return true; Log(("dbgDiggerLinuxIsLikelyNameFragment: failed at %RGv: bLead=%#x bTail=%#x (offTail=%#x)\n", pHitAddr->FlatPtr, bLead, bTail, offTail)); } else Log(("dbgDiggerLinuxIsLikelyNameFragment: failed at %RGv: Needle changed!\n", pHitAddr->FlatPtr)); } else Log(("dbgDiggerLinuxIsLikelyNameFragment: failed at %RGv: %Rrc\n", pHitAddr->FlatPtr, rc)); return false; } /** * Tries to find and load the kernel symbol table with the given needle. * * @returns VBox status code. * @param pThis The Linux digger data. * @param pUVM The user mode VM handle. * @param pabNeedle The needle to use for searching. * @param cbNeedle Size of the needle in bytes. */ static int dbgDiggerLinuxFindSymbolTableFromNeedle(PDBGDIGGERLINUX pThis, PUVM pUVM, uint8_t const *pabNeedle, uint8_t cbNeedle) { int rc = VINF_SUCCESS; /* * Go looking for the kallsyms table. If it's there, it will be somewhere * after the linux_banner symbol, so use it for starting the search. */ DBGFADDRESS CurAddr = pThis->AddrLinuxBanner; uint32_t cbLeft = LNX_MAX_KERNEL_SIZE; while (cbLeft > 4096) { DBGFADDRESS HitAddr; rc = DBGFR3MemScan(pUVM, 0 /*idCpu*/, &CurAddr, cbLeft, 1 /*uAlign*/, pabNeedle, cbNeedle, &HitAddr); if (RT_FAILURE(rc)) break; if (dbgDiggerLinuxIsLikelyNameFragment(pUVM, &HitAddr, pabNeedle, cbNeedle)) { /* There will be another hit near by. */ DBGFR3AddrAdd(&HitAddr, 1); rc = DBGFR3MemScan(pUVM, 0 /*idCpu*/, &HitAddr, LNX_MAX_KALLSYMS_NAMES_SIZE, 1 /*uAlign*/, pabNeedle, cbNeedle, &HitAddr); if ( RT_SUCCESS(rc) && dbgDiggerLinuxIsLikelyNameFragment(pUVM, &HitAddr, pabNeedle, cbNeedle)) { /* * We've got a very likely candidate for a location inside kallsyms_names. * Try find the start of it, that is to say, try find kallsyms_num_syms. * kallsyms_num_syms is aligned on sizeof(unsigned long) boundrary */ rc = dbgDiggerLinuxFindStartOfNamesAndSymbolCount(pUVM, pThis, &HitAddr); if (RT_SUCCESS(rc)) rc = dbgDiggerLinuxFindEndOfNamesAndMore(pUVM, pThis, &HitAddr); if (RT_SUCCESS(rc)) rc = dbgDiggerLinuxFindTokenIndex(pUVM, pThis); if (RT_SUCCESS(rc)) rc = dbgDiggerLinuxLoadKernelSymbols(pUVM, pThis); if (RT_SUCCESS(rc)) { rc = dbgDiggerLinuxLoadModules(pThis, pUVM); break; } } } /* * Advance. */ RTGCUINTPTR cbDistance = HitAddr.FlatPtr - CurAddr.FlatPtr + cbNeedle; if (RT_UNLIKELY(cbDistance >= cbLeft)) { Log(("dbgDiggerLinuxInit: Failed to find kallsyms\n")); break; } cbLeft -= cbDistance; DBGFR3AddrAdd(&CurAddr, cbDistance); } return rc; } /** * Skips whitespace and comments in the given config returning the pointer * to the first non whitespace character. * * @returns Pointer to the first non whitespace character or NULL if the end * of the string was reached. * @param pszCfg The config string. */ static const char *dbgDiggerLinuxCfgSkipWhitespace(const char *pszCfg) { do { while ( *pszCfg != '\0' && ( RT_C_IS_SPACE(*pszCfg) || *pszCfg == '\n')) pszCfg++; /* Do we have a comment? Skip it. */ if (*pszCfg == '#') { while ( *pszCfg != '\n' && *pszCfg != '\0') pszCfg++; } } while ( *pszCfg != '\0' && ( RT_C_IS_SPACE(*pszCfg) || *pszCfg == '\n' || *pszCfg == '#')); return pszCfg; } /** * Parses an identifier at the given position. * * @returns VBox status code. * @param pszCfg The config data. * @param ppszCfgNext Where to store the pointer to the data following the identifier. * @param ppszIde Where to store the pointer to the identifier on success. * Free with RTStrFree(). */ static int dbgDiggerLinuxCfgParseIde(const char *pszCfg, const char **ppszCfgNext, char **ppszIde) { int rc = VINF_SUCCESS; size_t cchIde = 0; while ( *pszCfg != '\0' && ( RT_C_IS_ALNUM(*pszCfg) || *pszCfg == '_')) { cchIde++; pszCfg++; } if (cchIde) { *ppszIde = RTStrDupN(pszCfg - cchIde, cchIde); if (!*ppszIde) rc = VERR_NO_STR_MEMORY; } *ppszCfgNext = pszCfg; return rc; } /** * Parses a value for a config item. * * @returns VBox status code. * @param pszCfg The config data. * @param ppszCfgNext Where to store the pointer to the data following the identifier. * @param ppCfgItem Where to store the created config item on success. */ static int dbgDiggerLinuxCfgParseVal(const char *pszCfg, const char **ppszCfgNext, PDBGDIGGERLINUXCFGITEM *ppCfgItem) { int rc = VINF_SUCCESS; PDBGDIGGERLINUXCFGITEM pCfgItem = NULL; if (RT_C_IS_DIGIT(*pszCfg) || *pszCfg == '-') { /* Parse the number. */ int64_t i64Num; rc = RTStrToInt64Ex(pszCfg, (char **)ppszCfgNext, 0, &i64Num); if ( RT_SUCCESS(rc) || rc == VWRN_TRAILING_CHARS || rc == VWRN_TRAILING_SPACES) { pCfgItem = (PDBGDIGGERLINUXCFGITEM)RTMemAllocZ(sizeof(DBGDIGGERLINUXCFGITEM)); if (pCfgItem) { pCfgItem->enmType = DBGDIGGERLINUXCFGITEMTYPE_NUMBER; pCfgItem->u.i64Num = i64Num; } else rc = VERR_NO_MEMORY; } } else if (*pszCfg == '\"') { /* Parse a string. */ const char *pszCfgCur = pszCfg + 1; while ( *pszCfgCur != '\0' && *pszCfgCur != '\"') pszCfgCur++; if (*pszCfgCur == '\"') { pCfgItem = (PDBGDIGGERLINUXCFGITEM)RTMemAllocZ(RT_UOFFSETOF_DYN(DBGDIGGERLINUXCFGITEM, u.aszString[pszCfgCur - pszCfg + 1])); if (pCfgItem) { pCfgItem->enmType = DBGDIGGERLINUXCFGITEMTYPE_STRING; RTStrCopyEx(&pCfgItem->u.aszString[0], pszCfgCur - pszCfg + 1, pszCfg, pszCfgCur - pszCfg); *ppszCfgNext = pszCfgCur + 1; } else rc = VERR_NO_MEMORY; } else rc = VERR_INVALID_STATE; } else if ( *pszCfg == 'y' || *pszCfg == 'm') { /* Included or module. */ pCfgItem = (PDBGDIGGERLINUXCFGITEM)RTMemAllocZ(sizeof(DBGDIGGERLINUXCFGITEM)); if (pCfgItem) { pCfgItem->enmType = DBGDIGGERLINUXCFGITEMTYPE_FLAG; pCfgItem->u.fModule = *pszCfg == 'm'; } else rc = VERR_NO_MEMORY; pszCfg++; *ppszCfgNext = pszCfg; } else rc = VERR_INVALID_STATE; if (RT_SUCCESS(rc)) *ppCfgItem = pCfgItem; else if (pCfgItem) RTMemFree(pCfgItem); return rc; } /** * Parses the given kernel config and creates the config database. * * @returns VBox status code * @param pThis The Linux digger data. * @param pszCfg The config string. */ static int dbgDiggerLinuxCfgParse(PDBGDIGGERLINUX pThis, const char *pszCfg) { int rc = VINF_SUCCESS; /* * The config is a text file with the following elements: * # starts a comment which goes till the end of the line * = where is an identifier consisting of * alphanumerical characters (including _) * denotes the value for the identifier and can have the following * formats: * (-)[0-9]* for numbers * "..." for a string value * m when a feature is enabled as a module * y when a feature is enabled * Newlines are used as a separator between values and mark the end * of a comment */ const char *pszCfgCur = pszCfg; while ( RT_SUCCESS(rc) && *pszCfgCur != '\0') { /* Start skipping the whitespace. */ pszCfgCur = dbgDiggerLinuxCfgSkipWhitespace(pszCfgCur); if ( pszCfgCur && *pszCfgCur != '\0') { char *pszIde = NULL; /* Must be an identifier, parse it. */ rc = dbgDiggerLinuxCfgParseIde(pszCfgCur, &pszCfgCur, &pszIde); if (RT_SUCCESS(rc)) { /* * Skip whitespace again (shouldn't be required because = follows immediately * in the observed configs). */ pszCfgCur = dbgDiggerLinuxCfgSkipWhitespace(pszCfgCur); if ( pszCfgCur && *pszCfgCur == '=') { pszCfgCur++; pszCfgCur = dbgDiggerLinuxCfgSkipWhitespace(pszCfgCur); if ( pszCfgCur && *pszCfgCur != '\0') { /* Get the value. */ PDBGDIGGERLINUXCFGITEM pCfgItem = NULL; rc = dbgDiggerLinuxCfgParseVal(pszCfgCur, &pszCfgCur, &pCfgItem); if (RT_SUCCESS(rc)) { pCfgItem->Core.pszString = pszIde; bool fRc = RTStrSpaceInsert(&pThis->hCfgDb, &pCfgItem->Core); if (!fRc) { RTStrFree(pszIde); RTMemFree(pCfgItem); rc = VERR_INVALID_STATE; } } } else rc = VERR_EOF; } else rc = VERR_INVALID_STATE; } if (RT_FAILURE(rc)) RTStrFree(pszIde); } else break; /* Reached the end of the config. */ } if (RT_FAILURE(rc)) dbgDiggerLinuxCfgDbDestroy(pThis); return rc; } /** * Decompresses the given config and validates the UTF-8 encoding. * * @returns VBox status code. * @param pbCfgComp The compressed config. * @param cbCfgComp Size of the compressed config. * @param ppszCfg Where to store the pointer to the decompressed config * on success. */ static int dbgDiggerLinuxCfgDecompress(const uint8_t *pbCfgComp, size_t cbCfgComp, char **ppszCfg) { int rc = VINF_SUCCESS; RTVFSIOSTREAM hVfsIos = NIL_RTVFSIOSTREAM; rc = RTVfsIoStrmFromBuffer(RTFILE_O_READ, pbCfgComp, cbCfgComp, &hVfsIos); if (RT_SUCCESS(rc)) { RTVFSIOSTREAM hVfsIosDecomp = NIL_RTVFSIOSTREAM; rc = RTZipGzipDecompressIoStream(hVfsIos, RTZIPGZIPDECOMP_F_ALLOW_ZLIB_HDR, &hVfsIosDecomp); if (RT_SUCCESS(rc)) { char *pszCfg = NULL; size_t cchCfg = 0; size_t cbRead = 0; do { uint8_t abBuf[_64K]; rc = RTVfsIoStrmRead(hVfsIosDecomp, abBuf, sizeof(abBuf), true /*fBlocking*/, &cbRead); if (rc == VINF_EOF && cbRead == 0) rc = VINF_SUCCESS; if ( RT_SUCCESS(rc) && cbRead > 0) { /* Append data. */ char *pszCfgNew = pszCfg; rc = RTStrRealloc(&pszCfgNew, cchCfg + cbRead + 1); if (RT_SUCCESS(rc)) { pszCfg = pszCfgNew; memcpy(pszCfg + cchCfg, &abBuf[0], cbRead); cchCfg += cbRead; pszCfg[cchCfg] = '\0'; /* Enforce string termination. */ } } } while (RT_SUCCESS(rc) && cbRead > 0); if (RT_SUCCESS(rc)) *ppszCfg = pszCfg; else if (RT_FAILURE(rc) && pszCfg) RTStrFree(pszCfg); RTVfsIoStrmRelease(hVfsIosDecomp); } RTVfsIoStrmRelease(hVfsIos); } return rc; } /** * Reads and decodes the compressed kernel config. * * @returns VBox status code. * @param pThis The Linux digger data. * @param pUVM The user mode VM handle. * @param pAddrStart The start address of the compressed config. * @param cbCfgComp The size of the compressed config. */ static int dbgDiggerLinuxCfgDecode(PDBGDIGGERLINUX pThis, PUVM pUVM, PCDBGFADDRESS pAddrStart, size_t cbCfgComp) { int rc = VINF_SUCCESS; uint8_t *pbCfgComp = (uint8_t *)RTMemTmpAlloc(cbCfgComp); if (!pbCfgComp) return VERR_NO_MEMORY; rc = DBGFR3MemRead(pUVM, 0 /*idCpu*/, pAddrStart, pbCfgComp, cbCfgComp); if (RT_SUCCESS(rc)) { char *pszCfg = NULL; rc = dbgDiggerLinuxCfgDecompress(pbCfgComp, cbCfgComp, &pszCfg); if (RT_SUCCESS(rc)) { if (RTStrIsValidEncoding(pszCfg)) rc = dbgDiggerLinuxCfgParse(pThis, pszCfg); else rc = VERR_INVALID_UTF8_ENCODING; RTStrFree(pszCfg); } } RTMemFree(pbCfgComp); return rc; } /** * Tries to find the compressed kernel config in the kernel address space * and sets up the config database. * * @returns VBox status code. * @param pThis The Linux digger data. * @param pUVM The user mode VM handle. */ static int dbgDiggerLinuxCfgFind(PDBGDIGGERLINUX pThis, PUVM pUVM) { int rc = VINF_SUCCESS; /* * Go looking for the IKCFG_ST string which indicates the start * of the compressed config file. */ static const uint8_t s_abCfgNeedleStart[] = "IKCFG_ST"; static const uint8_t s_abCfgNeedleEnd[] = "IKCFG_ED"; DBGFADDRESS CurAddr = pThis->AddrLinuxBanner; uint32_t cbLeft = LNX_MAX_KERNEL_SIZE; while (cbLeft > 4096) { DBGFADDRESS HitAddrStart; rc = DBGFR3MemScan(pUVM, 0 /*idCpu*/, &CurAddr, cbLeft, 1 /*uAlign*/, s_abCfgNeedleStart, sizeof(s_abCfgNeedleStart) - 1, &HitAddrStart); if (RT_FAILURE(rc)) break; /* Check for the end marker which shouldn't be that far away. */ DBGFR3AddrAdd(&HitAddrStart, sizeof(s_abCfgNeedleStart) - 1); DBGFADDRESS HitAddrEnd; rc = DBGFR3MemScan(pUVM, 0 /* idCpu */, &HitAddrStart, LNX_MAX_COMPRESSED_CFG_SIZE, 1 /* uAlign */, s_abCfgNeedleEnd, sizeof(s_abCfgNeedleEnd) - 1, &HitAddrEnd); if (RT_SUCCESS(rc)) { /* Allocate a buffer to hold the compressed data between the markers and fetch it. */ RTGCUINTPTR cbCfg = HitAddrEnd.FlatPtr - HitAddrStart.FlatPtr; Assert(cbCfg == (size_t)cbCfg); rc = dbgDiggerLinuxCfgDecode(pThis, pUVM, &HitAddrStart, cbCfg); if (RT_SUCCESS(rc)) break; } /* * Advance. */ RTGCUINTPTR cbDistance = HitAddrStart.FlatPtr - CurAddr.FlatPtr + sizeof(s_abCfgNeedleStart) - 1; if (RT_UNLIKELY(cbDistance >= cbLeft)) { LogFunc(("Failed to find compressed kernel config\n")); break; } cbLeft -= cbDistance; DBGFR3AddrAdd(&CurAddr, cbDistance); } return rc; } /** * Probes for a Linux kernel starting at the given address. * * @returns Flag whether something which looks like a valid Linux kernel was found. * @param pThis The Linux digger data. * @param pUVM The user mode VM handle. * @param uAddrStart The address to start scanning at. * @param cbScan How much to scan. */ static bool dbgDiggerLinuxProbeWithAddr(PDBGDIGGERLINUX pThis, PUVM pUVM, RTGCUINTPTR uAddrStart, size_t cbScan) { /* * Look for "Linux version " at the start of the rodata segment. * Hope that this comes before any message buffer or other similar string. */ DBGFADDRESS KernelAddr; DBGFR3AddrFromFlat(pUVM, &KernelAddr, uAddrStart); DBGFADDRESS HitAddr; int rc = DBGFR3MemScan(pUVM, 0, &KernelAddr, cbScan, 1, g_abLinuxVersion, sizeof(g_abLinuxVersion) - 1, &HitAddr); if (RT_SUCCESS(rc)) { char szTmp[128]; char const *pszX = &szTmp[sizeof(g_abLinuxVersion) - 1]; rc = DBGFR3MemReadString(pUVM, 0, &HitAddr, szTmp, sizeof(szTmp)); if ( RT_SUCCESS(rc) && ( ( pszX[0] == '2' /* 2.x.y with x in {0..6} */ && pszX[1] == '.' && pszX[2] >= '0' && pszX[2] <= '6') || ( pszX[0] >= '3' /* 3.x, 4.x, ... 9.x */ && pszX[0] <= '9' && pszX[1] == '.' && pszX[2] >= '0' && pszX[2] <= '9') ) ) { pThis->AddrKernelBase = KernelAddr; pThis->AddrLinuxBanner = HitAddr; return true; } } return false; } /** * Probes for a Linux kernel which has KASLR enabled. * * @returns Flag whether a possible candidate location was found. * @param pThis The Linux digger data. * @param pUVM The user mode VM handle. */ static bool dbgDiggerLinuxProbeKaslr(PDBGDIGGERLINUX pThis, PUVM pUVM) { /** * With KASLR the kernel is loaded at a different address at each boot making detection * more difficult for us. * * The randomization is done in arch/x86/boot/compressed/kaslr.c:choose_random_location() (as of Nov 2017). * At the end of the method a random offset is chosen using find_random_virt_addr() which is added to the * kernel map start in the caller (the start of the kernel depends on the bit size, see LNX32_KERNEL_ADDRESS_START * and LNX64_KERNEL_ADDRESS_START for 32bit and 64bit kernels respectively). * The lowest offset possible is LOAD_PHYSICAL_ADDR which is defined in arch/x86/include/asm/boot.h * using CONFIG_PHYSICAL_START aligned to CONFIG_PHYSICAL_ALIGN. * The default CONFIG_PHYSICAL_START and CONFIG_PHYSICAL_ALIGN are both 0x1000000 no matter whether a 32bit * or a 64bit kernel is used. So the lowest offset to the kernel start address is 0x1000000. * The find_random_virt_addr() the number of possible slots where the kernel can be placed based on the image size * is calculated using the following formula: * cSlots = ((KERNEL_IMAGE_SIZE - 0x1000000 (minimum) - image_size) / 0x1000000 (CONFIG_PHYSICAL_ALIGN)) + 1 * * KERNEL_IMAGE_SIZE is 1GB for 64bit kernels and 512MB for 32bit kernels, so the maximum number of slots (resulting * in the largest possible offset) can be achieved when image_size (which contains the real size of the kernel image * which is unknown for us) goes to 0 and a 1GB KERNEL_IMAGE_SIZE is assumed. With that the biggest cSlots which can be * achieved is 64. The chosen random offset is taken from a random long integer using kaslr_get_random_long() modulo the * number of slots which selects a slot between 0 and 63. The final offset is calculated using: * offAddr = random_addr * 0x1000000 (CONFIG_PHYSICAL_ALIGN) + 0x1000000 (minimum) * * So the highest offset the kernel can start is 0x40000000 which is 1GB (plus the maximum kernel size we defined). */ if (dbgDiggerLinuxProbeWithAddr(pThis, pUVM, LNX64_KERNEL_ADDRESS_START, _1G + LNX_MAX_KERNEL_SIZE)) return true; /* * 32bit variant, makes sure we don't exceed the 4GB address space or DBGFR3MemScan() returns VERR_DBGF_MEM_NOT_FOUND immediately * without searching the remainder of the address space. * * The default split is 3GB userspace and 1GB kernel, so we just search the entire upper 1GB kernel space. */ if (dbgDiggerLinuxProbeWithAddr(pThis, pUVM, LNX32_KERNEL_ADDRESS_START, _4G - LNX32_KERNEL_ADDRESS_START)) return true; return false; } /** * @copydoc DBGFOSREG::pfnInit */ static DECLCALLBACK(int) dbgDiggerLinuxInit(PUVM pUVM, void *pvData) { PDBGDIGGERLINUX pThis = (PDBGDIGGERLINUX)pvData; Assert(!pThis->fValid); /* * Assume 64-bit kernels all live way beyond 32-bit address space. */ pThis->f64Bit = pThis->AddrLinuxBanner.FlatPtr > UINT32_MAX; pThis->fRelKrnlAddr = false; pThis->hCfgDb = NULL; /* * Try to find the compressed kernel config and parse it before we try * to get the symbol table, the config database is required to select * the method to use. */ int rc = dbgDiggerLinuxCfgFind(pThis, pUVM); if (RT_FAILURE(rc)) LogFlowFunc(("Failed to find kernel config (%Rrc), no config database available\n", rc)); static const uint8_t s_abNeedle[] = "kobj"; rc = dbgDiggerLinuxFindSymbolTableFromNeedle(pThis, pUVM, s_abNeedle, sizeof(s_abNeedle) - 1); if (RT_FAILURE(rc)) { /* Try alternate needle (seen on older x86 Linux kernels). */ static const uint8_t s_abNeedleAlt[] = "kobjec"; rc = dbgDiggerLinuxFindSymbolTableFromNeedle(pThis, pUVM, s_abNeedleAlt, sizeof(s_abNeedleAlt) - 1); if (RT_FAILURE(rc)) { static const uint8_t s_abNeedleOSuseX86[] = "nmi"; /* OpenSuSe 10.2 x86 */ rc = dbgDiggerLinuxFindSymbolTableFromNeedle(pThis, pUVM, s_abNeedleOSuseX86, sizeof(s_abNeedleOSuseX86) - 1); } } pThis->fValid = true; return VINF_SUCCESS; } /** * @copydoc DBGFOSREG::pfnProbe */ static DECLCALLBACK(bool) dbgDiggerLinuxProbe(PUVM pUVM, void *pvData) { PDBGDIGGERLINUX pThis = (PDBGDIGGERLINUX)pvData; for (unsigned i = 0; i < RT_ELEMENTS(g_au64LnxKernelAddresses); i++) { if (dbgDiggerLinuxProbeWithAddr(pThis, pUVM, g_au64LnxKernelAddresses[i], LNX_MAX_KERNEL_SIZE)) return true; } /* Maybe the kernel uses KASLR. */ if (dbgDiggerLinuxProbeKaslr(pThis, pUVM)) return true; return false; } /** * @copydoc DBGFOSREG::pfnDestruct */ static DECLCALLBACK(void) dbgDiggerLinuxDestruct(PUVM pUVM, void *pvData) { RT_NOREF2(pUVM, pvData); } /** * @copydoc DBGFOSREG::pfnConstruct */ static DECLCALLBACK(int) dbgDiggerLinuxConstruct(PUVM pUVM, void *pvData) { RT_NOREF1(pUVM); PDBGDIGGERLINUX pThis = (PDBGDIGGERLINUX)pvData; pThis->IDmesg.u32Magic = DBGFOSIDMESG_MAGIC; pThis->IDmesg.pfnQueryKernelLog = dbgDiggerLinuxIDmsg_QueryKernelLog; pThis->IDmesg.u32EndMagic = DBGFOSIDMESG_MAGIC; return VINF_SUCCESS; } const DBGFOSREG g_DBGDiggerLinux = { /* .u32Magic = */ DBGFOSREG_MAGIC, /* .fFlags = */ 0, /* .cbData = */ sizeof(DBGDIGGERLINUX), /* .szName = */ "Linux", /* .pfnConstruct = */ dbgDiggerLinuxConstruct, /* .pfnDestruct = */ dbgDiggerLinuxDestruct, /* .pfnProbe = */ dbgDiggerLinuxProbe, /* .pfnInit = */ dbgDiggerLinuxInit, /* .pfnRefresh = */ dbgDiggerLinuxRefresh, /* .pfnTerm = */ dbgDiggerLinuxTerm, /* .pfnQueryVersion = */ dbgDiggerLinuxQueryVersion, /* .pfnQueryInterface = */ dbgDiggerLinuxQueryInterface, /* .pfnStackUnwindAssist = */ dbgDiggerLinuxStackUnwindAssist, /* .u32EndMagic = */ DBGFOSREG_MAGIC };