/* $Id: DBGPlugInCommonELFTmpl.cpp.h 82968 2020-02-04 10:35:17Z vboxsync $ */ /** @file * DBGPlugInCommonELF - Code Template for dealing with one kind of ELF. */ /* * 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. */ #if ELF_MODE == 32 # define Elf_Ehdr Elf32_Ehdr # define Elf_Shdr Elf32_Shdr # define Elf_Phdr Elf32_Phdr # define Elf_Sym Elf32_Sym # define MY_ELFCLASS ELFCLASS32 # define ELF_ST_BIND ELF32_ST_BIND # define DBGDiggerCommonParseElfMod DBGDiggerCommonParseElf32Mod #else # define Elf_Ehdr Elf64_Ehdr # define Elf_Shdr Elf64_Shdr # define Elf_Phdr Elf64_Phdr # define Elf_Sym Elf64_Sym # define MY_ELFCLASS ELFCLASS64 # define ELF_ST_BIND ELF64_ST_BIND # define DBGDiggerCommonParseElfMod DBGDiggerCommonParseElf64Mod #endif /** * Common ELF module parser. * * It takes the essential bits of the ELF module (elf header, section headers, * symbol table and string table), and inserts/updates the module and symbols. * * * @returns VBox status code. * * @param pUVM The user mode VM handle. * @param pszModName The module name. * @param pszFilename The filename. optional. * @param fFlags Flags. * @param pEhdr Pointer to the ELF header. * @param paShdrs Pointer to the section headers. The caller must verify that * the e_shnum member of the ELF header is within the bounds of * this table. The caller should also adjust the section addresses * so these correspond to actual load addresses. * @param paSyms Pointer to the symbol table. * @param cMaxSyms The maximum number of symbols paSyms may hold. This isn't * the exact count, it's just a cap for avoiding SIGSEGVs * and general corruption. * @param pbStrings Pointer to the string table. * @param cbMaxStrings The size of the memory pbStrings points to. This doesn't * have to match the string table size exactly, it's just to * avoid SIGSEGV when a bad string index is encountered. * @param MinAddr Min address to care about. * @param MaxAddr Max address to care about (inclusive). Together * with MinAddr this forms a valid address range for * symbols and sections that we care about. Anything * outside the range is ignored, except when doing * sanity checks.. * @param uModTag Module tag. Pass 0 if tagging is of no interest. */ int DBGDiggerCommonParseElfMod(PUVM pUVM, const char *pszModName, const char *pszFilename, uint32_t fFlags, Elf_Ehdr const *pEhdr, Elf_Shdr const *paShdrs, Elf_Sym const *paSyms, size_t cMaxSyms, char const *pbStrings, size_t cbMaxStrings, RTGCPTR MinAddr, RTGCPTR MaxAddr, uint64_t uModTag) { AssertPtrReturn(pUVM, VERR_INVALID_POINTER); AssertPtrReturn(pszModName, VERR_INVALID_POINTER); AssertPtrReturn(pszFilename, VERR_INVALID_POINTER); AssertReturn(!(fFlags & ~DBG_DIGGER_ELF_MASK), VERR_INVALID_PARAMETER); AssertReturn((fFlags & (DBG_DIGGER_ELF_FUNNY_SHDRS | DBG_DIGGER_ELF_ADJUST_SYM_VALUE)) != (DBG_DIGGER_ELF_FUNNY_SHDRS | DBG_DIGGER_ELF_ADJUST_SYM_VALUE), VERR_INVALID_PARAMETER); AssertPtrReturn(paShdrs, VERR_INVALID_POINTER); AssertPtrReturn(paSyms, VERR_INVALID_POINTER); AssertPtrReturn(pbStrings, VERR_INVALID_POINTER); /* * Validate the ELF header. */ if ( pEhdr->e_ident[EI_MAG0] != ELFMAG0 || pEhdr->e_ident[EI_MAG1] != ELFMAG1 || pEhdr->e_ident[EI_MAG2] != ELFMAG2 || pEhdr->e_ident[EI_MAG3] != ELFMAG3) return VERR_INVALID_EXE_SIGNATURE; if (pEhdr->e_ident[EI_CLASS] != MY_ELFCLASS) return VERR_LDRELF_MACHINE; if (pEhdr->e_ident[EI_DATA] != ELFDATA2LSB) return VERR_LDRELF_ODD_ENDIAN; if (pEhdr->e_ident[EI_VERSION] != EV_CURRENT) return VERR_LDRELF_VERSION; if (pEhdr->e_version != EV_CURRENT) return VERR_LDRELF_VERSION; if (pEhdr->e_ehsize != sizeof(*pEhdr)) return VERR_BAD_EXE_FORMAT; #if ELF_MODE == 32 if ( pEhdr->e_machine != EM_386 && pEhdr->e_machine != EM_486) return VERR_LDRELF_MACHINE; #else if (pEhdr->e_machine != EM_X86_64) return VERR_LDRELF_MACHINE; #endif if ( pEhdr->e_type != ET_DYN && pEhdr->e_type != ET_REL && pEhdr->e_type != ET_EXEC) //?? return VERR_BAD_EXE_FORMAT; if ( pEhdr->e_phentsize != sizeof(Elf_Phdr) && pEhdr->e_phentsize) //?? return VERR_BAD_EXE_FORMAT; if (pEhdr->e_shentsize != sizeof(Elf_Shdr)) return VERR_BAD_EXE_FORMAT; if (pEhdr->e_shentsize != sizeof(Elf_Shdr)) return VERR_BAD_EXE_FORMAT; if (!ASMMemIsZero(&pEhdr->e_ident[EI_PAD], EI_NIDENT - EI_PAD)) //?? return VERR_BAD_EXE_FORMAT; /* * Validate the section headers, finding the string and symbol table * headers and the load address while at it. */ uint64_t uLoadAddr = UINT64_MAX; const Elf_Shdr *pSymShdr = NULL; const Elf_Shdr *pStrShdr = NULL; for (unsigned iSh = fFlags & DBG_DIGGER_ELF_FUNNY_SHDRS ? 1 : 0; iSh < pEhdr->e_shnum; iSh++) { /* Minimal validation. */ if (paShdrs[iSh].sh_link >= pEhdr->e_shnum) return VERR_BAD_EXE_FORMAT; /* Is it the symbol table?*/ if (paShdrs[iSh].sh_type == SHT_SYMTAB) { if (pSymShdr) return VERR_LDRELF_MULTIPLE_SYMTABS; pSymShdr = &paShdrs[iSh]; if (pSymShdr->sh_entsize != sizeof(Elf32_Sym)) return VERR_BAD_EXE_FORMAT; pStrShdr = &paShdrs[paShdrs[iSh].sh_link]; } if (uLoadAddr > paShdrs[iSh].sh_addr) uLoadAddr = paShdrs[iSh].sh_addr; } /* * Validate the symbol table and determine the max section index * when DBG_DIGGER_ELF_FUNNY_SHDRS is flagged. */ uint32_t uMaxShIdx = fFlags & DBG_DIGGER_ELF_FUNNY_SHDRS ? 0 : pEhdr->e_shnum - 1; size_t const cbStrings = pStrShdr ? pStrShdr->sh_size : cbMaxStrings; size_t const cSyms = pSymShdr ? RT_MIN(cMaxSyms, pSymShdr->sh_size / sizeof(Elf_Sym)) : cMaxSyms; for (size_t iSym = 1; iSym < cSyms; iSym++) { if (paSyms[iSym].st_name >= cbStrings) return VERR_LDRELF_INVALID_SYMBOL_NAME_OFFSET; if (fFlags & DBG_DIGGER_ELF_FUNNY_SHDRS) { if ( paSyms[iSym].st_shndx > uMaxShIdx && paSyms[iSym].st_shndx < SHN_LORESERVE) uMaxShIdx = paSyms[iSym].st_shndx; } else if ( paSyms[iSym].st_shndx >= pEhdr->e_shnum && paSyms[iSym].st_shndx != SHN_UNDEF && ( paSyms[iSym].st_shndx < SHN_LORESERVE /*|| paSyms[iSym].st_shndx > SHN_HIRESERVE*/ || ELF_ST_BIND(paSyms[iSym].st_info) == STB_GLOBAL || ELF_ST_BIND(paSyms[iSym].st_info) == STB_WEAK) ) return VERR_BAD_EXE_FORMAT; } if (uMaxShIdx > 4096) return VERR_BAD_EXE_FORMAT; /* * Create new module. * The funny ELF section headers on solaris makes this very complicated. */ uint32_t cSegs = uMaxShIdx + 1; PDBGDIGGERELFSEG paSegs = (PDBGDIGGERELFSEG)alloca(sizeof(paSegs[0]) * cSegs); for (uint32_t i = 0; i < cSegs; i++) { paSegs[i].uLoadAddr = RTGCPTR_MAX; paSegs[i].uLastAddr = 0; paSegs[i].iSeg = NIL_RTDBGSEGIDX; } RTDBGMOD hMod; int rc = RTDbgModCreate(&hMod, pszModName, 0 /*cbSeg*/, 0 /*fFlags*/); if (RT_FAILURE(rc)) return rc; rc = RTDbgModSetTag(hMod, uModTag); AssertRC(rc); if (fFlags & DBG_DIGGER_ELF_FUNNY_SHDRS) { /* Seek out the min and max symbol values for each section. */ for (uint32_t iSym = 1; iSym < cSyms; iSym++) { /* Ignore undefined, absolute and weak symbols in this pass, but include local ones as well as nameless. */ uint32_t iSh = paSyms[iSym].st_shndx; if ( iSh != SHN_UNDEF && iSh < cSegs && ( ELF_ST_BIND(paSyms[iSym].st_info) == STB_GLOBAL || ELF_ST_BIND(paSyms[iSym].st_info) == STB_LOCAL)) { /* Calc the address and check that it doesn't wrap with the size. */ RTGCUINTPTR Address = paSyms[iSym].st_value; RTGCUINTPTR AddressLast = Address + RT_MAX(paSyms[iSym].st_size, 1) - 1; if (AddressLast < Address) continue; if ( Address < MinAddr || AddressLast > MaxAddr) continue; /* update min/max. */ if (Address < paSegs[iSh].uLoadAddr) paSegs[iSh].uLoadAddr = Address; if (AddressLast > paSegs[iSh].uLastAddr) paSegs[iSh].uLastAddr = AddressLast; } } /* Add the segments and fill in the translation table. */ RTGCPTR uRvaNext = 0; for (unsigned i = 0; i < cSegs; i++) if (paSegs[i].uLastAddr != 0) { char szSeg[32]; RTStrPrintf(szSeg, sizeof(szSeg), "sec%02u", i); RTGCPTR cbSeg = paSegs[i].uLastAddr - paSegs[i].uLoadAddr + 1; rc = RTDbgModSegmentAdd(hMod, uRvaNext, cbSeg, szSeg, 0 /*fFlags*/, &paSegs[i].iSeg); if (RT_FAILURE(rc)) break; uRvaNext += RT_ALIGN_T(cbSeg, 32, RTGCPTR); } } else { /* Add the segments and fill in the translation table. */ for (unsigned i = 0; i < cSegs; i++) if (paShdrs[i].sh_flags & SHF_ALLOC) { char szSeg[32]; RTStrPrintf(szSeg, sizeof(szSeg), "sec%02u", i); rc = RTDbgModSegmentAdd(hMod, paShdrs[i].sh_addr - uLoadAddr, paShdrs[i].sh_size, szSeg, 0 /*fFlags*/, &paSegs[i].iSeg); if (RT_FAILURE(rc)) break; paSegs[i].uLoadAddr = paShdrs[i].sh_addr; paSegs[i].uLastAddr = paShdrs[i].sh_addr + paShdrs[i].sh_size - 1; } } if (RT_FAILURE(rc)) { RTDbgModRelease(hMod); return rc; } /* * Add all relevant symbols in the module */ for (uint32_t iSym = 1; iSym < cSyms; iSym++) { /* Undefined symbols are not exports, they are imports. */ RTDBGSEGIDX iSeg = paSyms[iSym].st_shndx; if ( iSeg != SHN_UNDEF && ( ELF_ST_BIND(paSyms[iSym].st_info) == STB_GLOBAL || ELF_ST_BIND(paSyms[iSym].st_info) == STB_LOCAL || ELF_ST_BIND(paSyms[iSym].st_info) == STB_WEAK)) { /* Get the symbol name. */ if (paSyms[iSym].st_name >= cbMaxStrings) continue; const char *pszSymbol = pbStrings + paSyms[iSym].st_name; if (!*pszSymbol) continue; /* Calc the address (value) and size. */ RTGCUINTPTR cbSym = paSyms[iSym].st_size; RTGCUINTPTR offSeg = paSyms[iSym].st_value; if (iSeg == SHN_ABS) iSeg = RTDBGSEGIDX_ABS; /* absolute symbols are not subject to any relocation. */ else { Assert(iSeg < cSegs); if (fFlags & (DBG_DIGGER_ELF_FUNNY_SHDRS | DBG_DIGGER_ELF_ADJUST_SYM_VALUE)) offSeg -= paSegs[iSeg].uLoadAddr; iSeg = paSegs[iSeg].iSeg; if (iSeg == NIL_RTDBGSEGIDX) continue; } if (offSeg + cbSym < offSeg) continue; rc = RTDbgModSymbolAdd(hMod, pszSymbol, iSeg, offSeg, cbSym, 0 /*fFlags*/, NULL); Log(("%02x:%RGv %RGv %s!%s (rc=%Rrc)\n", paSyms[iSym].st_shndx, offSeg, cbSym, pszModName, pszSymbol, rc)); } /*else: silently ignore */ } /* * Link it into the address space. */ RTDBGAS hAs = DBGFR3AsResolveAndRetain(pUVM, DBGF_AS_KERNEL); if (hAs != NIL_RTDBGAS) rc = dbgDiggerCommonLinkElfSegs(hAs, hMod, paSegs, cSegs); else rc = VERR_INTERNAL_ERROR; RTDbgModRelease(hMod); RTDbgAsRelease(hAs); return rc; } #undef Elf_Ehdr #undef Elf_Shdr #undef Elf_Phdr #undef Elf_Sym #undef MY_ELFCLASS #undef ELF_ST_BIND #undef DBGDiggerCommonParseElfMod