| // Copyright (c) 2012, Google Inc. |
| // All rights reserved. |
| // |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above |
| // copyright notice, this list of conditions and the following disclaimer |
| // in the documentation and/or other materials provided with the |
| // distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived from |
| // this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #include "common/linux/elfutils.h" |
| |
| #include <assert.h> |
| #include <string.h> |
| |
| #include "common/linux/linux_libc_support.h" |
| #include "common/linux/elfutils-inl.h" |
| |
| namespace google_breakpad { |
| |
| namespace { |
| |
| template<typename ElfClass> |
| void FindElfClassSection(const char* elf_base, |
| const char* section_name, |
| typename ElfClass::Word section_type, |
| const void** section_start, |
| size_t* section_size) { |
| typedef typename ElfClass::Ehdr Ehdr; |
| typedef typename ElfClass::Shdr Shdr; |
| |
| assert(elf_base); |
| assert(section_start); |
| assert(section_size); |
| |
| assert(my_strncmp(elf_base, ELFMAG, SELFMAG) == 0); |
| |
| const Ehdr* elf_header = reinterpret_cast<const Ehdr*>(elf_base); |
| assert(elf_header->e_ident[EI_CLASS] == ElfClass::kClass); |
| |
| if (elf_header->e_shoff == 0) { |
| *section_start = NULL; |
| *section_size = 0; |
| return; |
| } |
| |
| const Shdr* sections = |
| GetOffset<ElfClass, Shdr>(elf_header, elf_header->e_shoff); |
| const Shdr* section_names = sections + elf_header->e_shstrndx; |
| const char* names = |
| GetOffset<ElfClass, char>(elf_header, section_names->sh_offset); |
| const char* names_end = names + section_names->sh_size; |
| |
| const Shdr* section = |
| FindElfSectionByName<ElfClass>(section_name, section_type, |
| sections, names, names_end, |
| elf_header->e_shnum); |
| |
| if (section != NULL && section->sh_size > 0) { |
| *section_start = elf_base + section->sh_offset; |
| *section_size = section->sh_size; |
| } |
| } |
| |
| template<typename ElfClass> |
| void FindElfClassSegment(const char* elf_base, |
| typename ElfClass::Word segment_type, |
| wasteful_vector<ElfSegment>* segments) { |
| typedef typename ElfClass::Ehdr Ehdr; |
| typedef typename ElfClass::Phdr Phdr; |
| |
| assert(elf_base); |
| assert(segments); |
| |
| assert(my_strncmp(elf_base, ELFMAG, SELFMAG) == 0); |
| |
| const Ehdr* elf_header = reinterpret_cast<const Ehdr*>(elf_base); |
| assert(elf_header->e_ident[EI_CLASS] == ElfClass::kClass); |
| |
| const Phdr* phdrs = |
| GetOffset<ElfClass, Phdr>(elf_header, elf_header->e_phoff); |
| |
| for (int i = 0; i < elf_header->e_phnum; ++i) { |
| if (phdrs[i].p_type == segment_type) { |
| ElfSegment seg = {}; |
| seg.start = elf_base + phdrs[i].p_offset; |
| seg.size = phdrs[i].p_filesz; |
| segments->push_back(seg); |
| } |
| } |
| } |
| |
| } // namespace |
| |
| bool IsValidElf(const void* elf_base) { |
| return my_strncmp(reinterpret_cast<const char*>(elf_base), |
| ELFMAG, SELFMAG) == 0; |
| } |
| |
| int ElfClass(const void* elf_base) { |
| const ElfW(Ehdr)* elf_header = |
| reinterpret_cast<const ElfW(Ehdr)*>(elf_base); |
| |
| return elf_header->e_ident[EI_CLASS]; |
| } |
| |
| bool FindElfSection(const void* elf_mapped_base, |
| const char* section_name, |
| uint32_t section_type, |
| const void** section_start, |
| size_t* section_size) { |
| assert(elf_mapped_base); |
| assert(section_start); |
| assert(section_size); |
| |
| *section_start = NULL; |
| *section_size = 0; |
| |
| if (!IsValidElf(elf_mapped_base)) |
| return false; |
| |
| int cls = ElfClass(elf_mapped_base); |
| const char* elf_base = |
| static_cast<const char*>(elf_mapped_base); |
| |
| if (cls == ELFCLASS32) { |
| FindElfClassSection<ElfClass32>(elf_base, section_name, section_type, |
| section_start, section_size); |
| return *section_start != NULL; |
| } else if (cls == ELFCLASS64) { |
| FindElfClassSection<ElfClass64>(elf_base, section_name, section_type, |
| section_start, section_size); |
| return *section_start != NULL; |
| } |
| |
| return false; |
| } |
| |
| bool FindElfSegments(const void* elf_mapped_base, |
| uint32_t segment_type, |
| wasteful_vector<ElfSegment>* segments) { |
| assert(elf_mapped_base); |
| assert(segments); |
| |
| if (!IsValidElf(elf_mapped_base)) |
| return false; |
| |
| int cls = ElfClass(elf_mapped_base); |
| const char* elf_base = |
| static_cast<const char*>(elf_mapped_base); |
| |
| if (cls == ELFCLASS32) { |
| FindElfClassSegment<ElfClass32>(elf_base, segment_type, segments); |
| return true; |
| } else if (cls == ELFCLASS64) { |
| FindElfClassSegment<ElfClass64>(elf_base, segment_type, segments); |
| return true; |
| } |
| |
| return false; |
| } |
| |
| template <typename ElfClass> |
| bool FindElfSoNameFromDynamicSection(const void* section_start, |
| size_t section_size, |
| const void* dynstr_start, |
| size_t dynstr_size, |
| char* soname, |
| size_t soname_size) { |
| typedef typename ElfClass::Dyn Dyn; |
| |
| auto* dynamic = static_cast<const Dyn*>(section_start); |
| size_t dcount = section_size / sizeof(Dyn); |
| for (const Dyn* dyn = dynamic; dyn < dynamic + dcount; ++dyn) { |
| if (dyn->d_tag == DT_SONAME) { |
| const char* dynstr = static_cast<const char*>(dynstr_start); |
| if (dyn->d_un.d_val >= dynstr_size) { |
| // Beyond the end of the dynstr section |
| return false; |
| } |
| const char* str = dynstr + dyn->d_un.d_val; |
| const size_t maxsize = dynstr_size - dyn->d_un.d_val; |
| my_strlcpy(soname, str, maxsize < soname_size ? maxsize : soname_size); |
| return true; |
| } |
| } |
| |
| return false; |
| } |
| |
| bool ElfFileSoNameFromMappedFile(const void* elf_base, |
| char* soname, |
| size_t soname_size) { |
| if (!IsValidElf(elf_base)) { |
| // Not ELF |
| return false; |
| } |
| |
| const void* segment_start; |
| size_t segment_size; |
| if (!FindElfSection(elf_base, ".dynamic", SHT_DYNAMIC, &segment_start, |
| &segment_size)) { |
| // No dynamic section |
| return false; |
| } |
| |
| const void* dynstr_start; |
| size_t dynstr_size; |
| if (!FindElfSection(elf_base, ".dynstr", SHT_STRTAB, &dynstr_start, |
| &dynstr_size)) { |
| // No dynstr section |
| return false; |
| } |
| |
| int cls = ElfClass(elf_base); |
| return cls == ELFCLASS32 ? FindElfSoNameFromDynamicSection<ElfClass32>( |
| segment_start, segment_size, dynstr_start, |
| dynstr_size, soname, soname_size) |
| : FindElfSoNameFromDynamicSection<ElfClass64>( |
| segment_start, segment_size, dynstr_start, |
| dynstr_size, soname, soname_size); |
| } |
| |
| } // namespace google_breakpad |
