From c51099bb1018191964e5ee05e17f133233160806 Mon Sep 17 00:00:00 2001 From: James Cowgill Date: Thu, 13 Oct 2016 11:00:00 +0100 Subject: [PATCH] MIPS: Handle DT_MIPS_RLD_MAP_REL tag when removing RPath from ELFs This is a combination of 5 commits. elf: remove tag switch from ELF_Dyn ByteSwap function elf: add DynamicEntryList methods and rpath tag constants cmSystemTools: rewrite RemoveRPath using DyanmicEntryList methods cmSystemTools, elf: handle DT_MIPS_RLD_REL_MAP in RemoveRPath elf: Remove GetDynamicEntryCount and ReadBytes methods diff --git a/Source/cmELF.cxx b/Source/cmELF.cxx index 2d86674..0655da9 100644 --- a/Source/cmELF.cxx +++ b/Source/cmELF.cxx @@ -132,18 +132,13 @@ public: // Forward to the per-class implementation. virtual unsigned int GetNumberOfSections() const = 0; - virtual unsigned int GetDynamicEntryCount() = 0; virtual unsigned long GetDynamicEntryPosition(int j) = 0; + virtual cmELF::DynamicEntryList GetDynamicEntries() = 0; + virtual std::vector EncodeDynamicEntries( + const cmELF::DynamicEntryList&) = 0; virtual StringEntry const* GetDynamicSectionString(unsigned int tag) = 0; virtual void PrintInfo(std::ostream& os) const = 0; - bool ReadBytes(unsigned long pos, unsigned long size, char* buf) - { - this->Stream.seekg(pos); - this->Stream.read(buf, size); - return !this->Stream.fail(); - } - // Lookup the SONAME in the DYNAMIC section. StringEntry const* GetSOName() { @@ -246,10 +241,13 @@ public: return static_cast(this->ELFHeader.e_shnum); } - // Get the file position and size of a dynamic section entry. - unsigned int GetDynamicEntryCount() CM_OVERRIDE; + // Get the file position of a dynamic section entry. unsigned long GetDynamicEntryPosition(int j) CM_OVERRIDE; + cmELF::DynamicEntryList GetDynamicEntries() CM_OVERRIDE; + std::vector EncodeDynamicEntries(const cmELF::DynamicEntryList&) + CM_OVERRIDE; + // Lookup a string from the dynamic section with the given tag. StringEntry const* GetDynamicSectionString(unsigned int tag) CM_OVERRIDE; @@ -289,6 +287,10 @@ public: } private: + // ByteSwap(ELF_Dyn) assumes d_val and d_ptr are the same size + typedef char dyn_size_assert + [sizeof(ELF_Dyn().d_un.d_val) == sizeof(ELF_Dyn().d_un.d_ptr) ? 1 : -1]; + void ByteSwap(ELF_Ehdr& elf_header) { cmELFByteSwap(elf_header.e_type); @@ -323,121 +325,7 @@ private: void ByteSwap(ELF_Dyn& dyn) { cmELFByteSwap(dyn.d_tag); - switch (dyn.d_tag) { - case DT_NULL: /* dyn.d_un ignored */ - break; - case DT_NEEDED: - cmELFByteSwap(dyn.d_un.d_val); - break; - case DT_PLTRELSZ: - cmELFByteSwap(dyn.d_un.d_val); - break; - case DT_PLTGOT: - cmELFByteSwap(dyn.d_un.d_ptr); - break; - case DT_HASH: - cmELFByteSwap(dyn.d_un.d_ptr); - break; - case DT_STRTAB: - cmELFByteSwap(dyn.d_un.d_ptr); - break; - case DT_SYMTAB: - cmELFByteSwap(dyn.d_un.d_ptr); - break; - case DT_RELA: - cmELFByteSwap(dyn.d_un.d_ptr); - break; - case DT_RELASZ: - cmELFByteSwap(dyn.d_un.d_val); - break; - case DT_RELAENT: - cmELFByteSwap(dyn.d_un.d_val); - break; - case DT_STRSZ: - cmELFByteSwap(dyn.d_un.d_val); - break; - case DT_SYMENT: - cmELFByteSwap(dyn.d_un.d_val); - break; - case DT_INIT: - cmELFByteSwap(dyn.d_un.d_ptr); - break; - case DT_FINI: - cmELFByteSwap(dyn.d_un.d_ptr); - break; - case DT_SONAME: - cmELFByteSwap(dyn.d_un.d_val); - break; - case DT_RPATH: - cmELFByteSwap(dyn.d_un.d_val); - break; - case DT_SYMBOLIC: /* dyn.d_un ignored */ - break; - case DT_REL: - cmELFByteSwap(dyn.d_un.d_ptr); - break; - case DT_RELSZ: - cmELFByteSwap(dyn.d_un.d_val); - break; - case DT_RELENT: - cmELFByteSwap(dyn.d_un.d_val); - break; - case DT_PLTREL: - cmELFByteSwap(dyn.d_un.d_val); - break; - case DT_DEBUG: - cmELFByteSwap(dyn.d_un.d_ptr); - break; - case DT_TEXTREL: /* dyn.d_un ignored */ - break; - case DT_JMPREL: - cmELFByteSwap(dyn.d_un.d_ptr); - break; -#ifdef T_BIND_NOW - case T_BIND_NOW: /* dyn.d_un ignored */ - break; -#endif -#ifdef DT_INIT_ARRAY - case DT_INIT_ARRAY: - cmELFByteSwap(dyn.d_un.d_ptr); - break; -#endif -#ifdef DT_FINI_ARRAY - case DT_FINI_ARRAY: - cmELFByteSwap(dyn.d_un.d_ptr); - break; -#endif -#ifdef DT_INIT_ARRAYSZ - case DT_INIT_ARRAYSZ: - cmELFByteSwap(dyn.d_un.d_val); - break; -#endif -#ifdef DT_FINI_ARRAYSZ - case DT_FINI_ARRAYSZ: - cmELFByteSwap(dyn.d_un.d_val); - break; -#endif -#ifdef DT_RUNPATH - case DT_RUNPATH: - cmELFByteSwap(dyn.d_un.d_val); - break; -#endif -#ifdef DT_FLAGS - case DT_FLAGS: - cmELFByteSwap(dyn.d_un.d_val); - break; -#endif -#ifdef DT_PREINIT_ARRAY - case DT_PREINIT_ARRAY: - cmELFByteSwap(dyn.d_un.d_ptr); - break; -#endif -#ifdef DT_PREINIT_ARRAYSZ - case DT_PREINIT_ARRAYSZ: - cmELFByteSwap(dyn.d_un.d_val); - break; -#endif - } + cmELFByteSwap(dyn.d_un.d_val); } bool FileTypeValid(ELF_Half et) @@ -636,30 +524,64 @@ bool cmELFInternalImpl::LoadDynamicSection() } template -unsigned int cmELFInternalImpl::GetDynamicEntryCount() +unsigned long cmELFInternalImpl::GetDynamicEntryPosition(int j) { if (!this->LoadDynamicSection()) { return 0; } - for (unsigned int i = 0; i < this->DynamicSectionEntries.size(); ++i) { - if (this->DynamicSectionEntries[i].d_tag == DT_NULL) { - return i; - } + if (j < 0 || j >= static_cast(this->DynamicSectionEntries.size())) { + return 0; } - return static_cast(this->DynamicSectionEntries.size()); + ELF_Shdr const& sec = this->SectionHeaders[this->DynamicSectionIndex]; + return static_cast(sec.sh_offset + sec.sh_entsize * j); } template -unsigned long cmELFInternalImpl::GetDynamicEntryPosition(int j) +cmELF::DynamicEntryList cmELFInternalImpl::GetDynamicEntries() { + cmELF::DynamicEntryList result; + + // Ensure entries have been read from file if (!this->LoadDynamicSection()) { - return 0; + return result; } - if (j < 0 || j >= static_cast(this->DynamicSectionEntries.size())) { - return 0; + + // Copy into public array + result.reserve(this->DynamicSectionEntries.size()); + for (typename std::vector::iterator di = + this->DynamicSectionEntries.begin(); + di != this->DynamicSectionEntries.end(); ++di) { + ELF_Dyn& dyn = *di; + result.push_back( + std::pair(dyn.d_tag, dyn.d_un.d_val)); } - ELF_Shdr const& sec = this->SectionHeaders[this->DynamicSectionIndex]; - return static_cast(sec.sh_offset + sec.sh_entsize * j); + + return result; +} + +template +std::vector cmELFInternalImpl::EncodeDynamicEntries( + const cmELF::DynamicEntryList& entries) +{ + std::vector result; + result.reserve(sizeof(ELF_Dyn) * entries.size()); + + for (cmELF::DynamicEntryList::const_iterator it = entries.begin(); + it != entries.end(); it++) { + // Store the entry in an ELF_Dyn, byteswap it, then serialize to chars + ELF_Dyn dyn; + dyn.d_tag = static_cast(it->first); + dyn.d_un.d_val = static_cast(it->second); + + if (this->NeedSwap) { + ByteSwap(dyn); + } + + char* pdyn = reinterpret_cast(&dyn); + result.insert(result.end(), pdyn, pdyn + sizeof(ELF_Dyn)); + } + + return result; } template @@ -752,6 +674,15 @@ cmELF::StringEntry const* cmELFInternalImpl::GetDynamicSectionString( //============================================================================ // External class implementation. +const long cmELF::TagRPath = DT_RPATH; +const long cmELF::TagRunPath = DT_RUNPATH; + +#ifdef DT_MIPS_RLD_MAP_REL +const long cmELF::TagMipsRldMapRel = DT_MIPS_RLD_MAP_REL; +#else +const long cmELF::TagMipsRldMapRel = 0; +#endif + cmELF::cmELF(const char* fname) : Internal(CM_NULLPTR) { @@ -839,28 +770,31 @@ unsigned int cmELF::GetNumberOfSections() const return 0; } -unsigned int cmELF::GetDynamicEntryCount() const +unsigned long cmELF::GetDynamicEntryPosition(int index) const { if (this->Valid()) { - return this->Internal->GetDynamicEntryCount(); + return this->Internal->GetDynamicEntryPosition(index); } return 0; } -unsigned long cmELF::GetDynamicEntryPosition(int index) const +cmELF::DynamicEntryList cmELF::GetDynamicEntries() const { if (this->Valid()) { - return this->Internal->GetDynamicEntryPosition(index); + return this->Internal->GetDynamicEntries(); } - return 0; + + return cmELF::DynamicEntryList(); } -bool cmELF::ReadBytes(unsigned long pos, unsigned long size, char* buf) const +std::vector cmELF::EncodeDynamicEntries( + const cmELF::DynamicEntryList& dentries) const { if (this->Valid()) { - return this->Internal->ReadBytes(pos, size, buf); + return this->Internal->EncodeDynamicEntries(dentries); } - return false; + + return std::vector(); } bool cmELF::GetSOName(std::string& soname) diff --git a/Source/cmELF.h b/Source/cmELF.h index 7e7c1d6..763a240 100644 --- a/Source/cmELF.h +++ b/Source/cmELF.h @@ -7,6 +7,8 @@ #include #include +#include +#include #if !defined(CMAKE_USE_ELF_PARSER) #error "This file may be included only if CMAKE_USE_ELF_PARSER is enabled." @@ -61,22 +63,27 @@ public: int IndexInSection; }; + /** Represent entire dynamic section header */ + typedef std::vector > DynamicEntryList; + /** Get the type of the file opened. */ FileType GetFileType() const; /** Get the number of ELF sections present. */ unsigned int GetNumberOfSections() const; - /** Get the number of DYNAMIC section entries before the first - DT_NULL. Returns zero on error. */ - unsigned int GetDynamicEntryCount() const; - /** Get the position of a DYNAMIC section header entry. Returns zero on error. */ unsigned long GetDynamicEntryPosition(int index) const; - /** Read bytes from the file. */ - bool ReadBytes(unsigned long pos, unsigned long size, char* buf) const; + /** Get a copy of all the DYNAMIC section header entries. + Returns an empty vector on error */ + DynamicEntryList GetDynamicEntries() const; + + /** Encodes a DYNAMIC section header entry list into a char vector according + to the type of ELF file this is */ + std::vector EncodeDynamicEntries( + const DynamicEntryList& entries) const; /** Get the SONAME field if any. */ bool GetSOName(std::string& soname); @@ -91,6 +98,10 @@ public: /** Print human-readable information about the ELF file. */ void PrintInfo(std::ostream& os) const; + /** Interesting dynamic tags. + If the tag is 0, it does not exist in the host ELF implementation */ + static const long TagRPath, TagRunPath, TagMipsRldMapRel; + private: friend class cmELFInternal; bool Valid() const; diff --git a/Source/cmSystemTools.cxx b/Source/cmSystemTools.cxx index 3d8fdf5..d800ef8 100644 --- a/Source/cmSystemTools.cxx +++ b/Source/cmSystemTools.cxx @@ -2518,9 +2518,9 @@ bool cmSystemTools::RemoveRPath(std::string const& file, std::string* emsg, std::swap(se[0], se[1]); } - // Get the size of the dynamic section header. - unsigned int count = elf.GetDynamicEntryCount(); - if (count == 0) { + // Obtain a copy of the dynamic entries + cmELF::DynamicEntryList dentries = elf.GetDynamicEntries(); + if (dentries.empty()) { // This should happen only for invalid ELF files where a DT_NULL // appears before the end of the table. if (emsg) { @@ -2536,40 +2536,46 @@ bool cmSystemTools::RemoveRPath(std::string const& file, std::string* emsg, zeroSize[i] = se[i]->Size; } - // Get the range of file positions corresponding to each entry and - // the rest of the table after them. - unsigned long entryBegin[3] = { 0, 0, 0 }; - unsigned long entryEnd[2] = { 0, 0 }; - for (int i = 0; i < se_count; ++i) { - entryBegin[i] = elf.GetDynamicEntryPosition(se[i]->IndexInSection); - entryEnd[i] = elf.GetDynamicEntryPosition(se[i]->IndexInSection + 1); - } - entryBegin[se_count] = elf.GetDynamicEntryPosition(count); - - // The data are to be written over the old table entries starting at - // the first one being removed. - bytesBegin = entryBegin[0]; - unsigned long bytesEnd = entryBegin[se_count]; + // Get size of one DYNAMIC entry + unsigned long const sizeof_dentry = + elf.GetDynamicEntryPosition(1) - elf.GetDynamicEntryPosition(0); - // Allocate a buffer to hold the part of the file to be written. - // Initialize it with zeros. - bytes.resize(bytesEnd - bytesBegin, 0); - - // Read the part of the DYNAMIC section header that will move. - // The remainder of the buffer will be left with zeros which - // represent a DT_NULL entry. - char* data = &bytes[0]; - for (int i = 0; i < se_count; ++i) { - // Read data between the entries being removed. - unsigned long sz = entryBegin[i + 1] - entryEnd[i]; - if (sz > 0 && !elf.ReadBytes(entryEnd[i], sz, data)) { - if (emsg) { - *emsg = "Failed to read DYNAMIC section header."; + // Adjust the entry list as necessary to remove the run path + unsigned long entriesErased = 0; + for (cmELF::DynamicEntryList::iterator it = dentries.begin(); + it != dentries.end();) { + if (it->first == cmELF::TagRPath || it->first == cmELF::TagRunPath) { + it = dentries.erase(it); + entriesErased++; + continue; + } else { + if (cmELF::TagMipsRldMapRel != 0 && + it->first == cmELF::TagMipsRldMapRel) { + // Background: debuggers need to know the "linker map" which contains + // the addresses each dynamic object is loaded at. Most arches use + // the DT_DEBUG tag which the dynamic linker writes to (directly) and + // contain the location of the linker map, however on MIPS the + // .dynamic section is always read-only so this is not possible. MIPS + // objects instead contain a DT_MIPS_RLD_MAP tag which contains the + // address where the dyanmic linker will write to (an indirect + // version of DT_DEBUG). Since this doesn't work when using PIE, a + // relative equivalent was created - DT_MIPS_RLD_MAP_REL. Since this + // version contains a relative offset, moving it changes the + // calculated address. This may cause the dyanmic linker to write + // into memory it should not be changing. + // + // To fix this, we adjust the value of DT_MIPS_RLD_MAP_REL here. If + // we move it up by n bytes, we add n bytes to the value of this tag. + it->second += entriesErased * sizeof_dentry; } - return false; + + it++; } - data += sz; } + + // Encode new entries list + bytes = elf.EncodeDynamicEntries(dentries); + bytesBegin = elf.GetDynamicEntryPosition(0); } // Open the file for update.