feat(nid): remap dynamic needed offsets
This commit is contained in:
boykopovar
parent
e838a2d9df
commit
b1f51a3e4b
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@ -57,6 +57,33 @@ struct Elf64_Rela {
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std::int64_t r_addend;
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};
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struct Elf64_Dyn {
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std::int64_t d_tag;
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std::uint64_t d_val;
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};
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struct Elf64_Verneed {
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std::uint16_t vn_version;
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std::uint16_t vn_cnt;
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std::uint32_t vn_file;
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std::uint32_t vn_aux;
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std::uint32_t vn_next;
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};
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struct Elf64_Vernaux {
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std::uint32_t vna_hash;
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std::uint16_t vna_flags;
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std::uint16_t vna_other;
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std::uint32_t vna_name;
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std::uint32_t vna_next;
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};
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constexpr std::int64_t kDtNeeded = 1;
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constexpr std::int64_t kDtSoname = 14;
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constexpr std::int64_t kDtNull = 0;
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constexpr std::uint32_t kShtDynamic = 6u;
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constexpr std::uint32_t kShtGnuVerneed = 0x6ffffffeu;
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constexpr std::uint32_t kShtDynsym = 11u;
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constexpr std::uint32_t kShtGnuHash = 0x6ffffff6u;
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constexpr std::uint32_t kShtRela = 4u;
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@ -230,6 +257,147 @@ void RebuildGnuHash(
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std::memset(elf.data() + sectionOffset + requiredSize, 0, sectionSize - requiredSize);
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}
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void RemapDynamicNeededOffsets(
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std::vector<std::uint8_t>& elf,
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const Elf64_Ehdr& ehdr,
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const std::vector<std::pair<std::uint32_t, std::uint32_t>>& oldToNewOffset
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) {
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using namespace Internal;
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for (std::uint16_t i = 0u; i < ehdr.e_shnum; ++i) {
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const std::size_t shOffset = static_cast<std::size_t>(ehdr.e_shoff) + i * sizeof(Elf64_Shdr);
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const auto shdr = Read<Elf64_Shdr>(elf, shOffset);
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if (shdr.sh_type != kShtDynamic) continue;
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const std::size_t dynOffset = static_cast<std::size_t>(shdr.sh_offset);
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const std::size_t dynCount = static_cast<std::size_t>(shdr.sh_size) / sizeof(Elf64_Dyn);
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for (std::size_t d = 0u; d < dynCount; ++d) {
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const std::size_t entryOffset = dynOffset + d * sizeof(Elf64_Dyn);
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const auto dyn = Read<Elf64_Dyn>(elf, entryOffset);
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if (dyn.d_tag != kDtNeeded && dyn.d_tag != kDtSoname) continue;
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const auto oldNameOffset = static_cast<std::uint32_t>(dyn.d_val);
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const auto mapped = std::find_if(
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oldToNewOffset.begin(), oldToNewOffset.end(),
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[&](const auto& entry) { return entry.first == oldNameOffset; }
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);
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if (mapped == oldToNewOffset.end()) continue;
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Write(elf, entryOffset + offsetof(Elf64_Dyn, d_val), static_cast<std::uint64_t>(mapped->second));
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}
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}
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}
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void RemapVerneedOffsets(
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std::vector<std::uint8_t>& elf,
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const Elf64_Ehdr& ehdr,
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const std::vector<std::pair<std::uint32_t, std::uint32_t>>& oldToNewOffset
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) {
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using namespace Internal;
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for (std::uint16_t i = 0u; i < ehdr.e_shnum; ++i) {
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const std::size_t shOffset = static_cast<std::size_t>(ehdr.e_shoff) + i * sizeof(Elf64_Shdr);
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const auto shdr = Read<Elf64_Shdr>(elf, shOffset);
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if (shdr.sh_type != kShtGnuVerneed) continue;
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const std::size_t verneedOffset = static_cast<std::size_t>(shdr.sh_offset);
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std::size_t entryOffset = verneedOffset;
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while (true) {
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const auto verneed = Read<Elf64_Verneed>(elf, entryOffset);
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const auto mappedFile = std::find_if(
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oldToNewOffset.begin(), oldToNewOffset.end(),
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[&](const auto& entry) { return entry.first == verneed.vn_file; }
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);
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if (mappedFile != oldToNewOffset.end())
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Write(elf, entryOffset + offsetof(Elf64_Verneed, vn_file), mappedFile->second);
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std::size_t auxOffset = entryOffset + verneed.vn_aux;
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for (std::uint16_t a = 0u; a < verneed.vn_cnt; ++a) {
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const auto vernaux = Read<Elf64_Vernaux>(elf, auxOffset);
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const auto mappedName = std::find_if(
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oldToNewOffset.begin(), oldToNewOffset.end(),
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[&](const auto& entry) { return entry.first == vernaux.vna_name; }
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);
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if (mappedName != oldToNewOffset.end())
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Write(elf, auxOffset + offsetof(Elf64_Vernaux, vna_name), mappedName->second);
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if (vernaux.vna_next == 0u) break;
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auxOffset += vernaux.vna_next;
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}
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if (verneed.vn_next == 0u) break;
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entryOffset += verneed.vn_next;
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}
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}
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}
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std::vector<std::uint32_t> CollectDynamicNameOffsets(
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const std::vector<std::uint8_t>& elf,
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const Elf64_Ehdr& ehdr
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) {
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using namespace Internal;
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std::vector<std::uint32_t> offsets;
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for (std::uint16_t i = 0u; i < ehdr.e_shnum; ++i) {
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const std::size_t shOffset = static_cast<std::size_t>(ehdr.e_shoff) + i * sizeof(Elf64_Shdr);
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const auto shdr = Read<Elf64_Shdr>(elf, shOffset);
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if (shdr.sh_type != kShtDynamic) continue;
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const std::size_t dynOffset = static_cast<std::size_t>(shdr.sh_offset);
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const std::size_t dynCount = static_cast<std::size_t>(shdr.sh_size) / sizeof(Elf64_Dyn);
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for (std::size_t d = 0u; d < dynCount; ++d) {
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const auto dyn = Read<Elf64_Dyn>(elf, dynOffset + d * sizeof(Elf64_Dyn));
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if (dyn.d_tag == kDtNull) break;
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if (dyn.d_tag != kDtNeeded && dyn.d_tag != kDtSoname) continue;
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offsets.push_back(static_cast<std::uint32_t>(dyn.d_val));
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}
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}
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return offsets;
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}
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std::vector<std::uint32_t> CollectVerneedNameOffsets(
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const std::vector<std::uint8_t>& elf,
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const Elf64_Ehdr& ehdr
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) {
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using namespace Internal;
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std::vector<std::uint32_t> offsets;
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for (std::uint16_t i = 0u; i < ehdr.e_shnum; ++i) {
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const std::size_t shOffset = static_cast<std::size_t>(ehdr.e_shoff) + i * sizeof(Elf64_Shdr);
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const auto shdr = Read<Elf64_Shdr>(elf, shOffset);
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if (shdr.sh_type != kShtGnuVerneed) continue;
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std::size_t entryOffset = static_cast<std::size_t>(shdr.sh_offset);
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while (true) {
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const auto verneed = Read<Elf64_Verneed>(elf, entryOffset);
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offsets.push_back(verneed.vn_file);
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std::size_t auxOffset = entryOffset + verneed.vn_aux;
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for (std::uint16_t a = 0u; a < verneed.vn_cnt; ++a) {
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const auto vernaux = Read<Elf64_Vernaux>(elf, auxOffset);
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offsets.push_back(vernaux.vna_name);
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if (vernaux.vna_next == 0u) break;
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auxOffset += vernaux.vna_next;
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}
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if (verneed.vn_next == 0u) break;
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entryOffset += verneed.vn_next;
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}
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}
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return offsets;
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}
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}
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void ElfNidPatcher::PatchNids(std::vector<std::uint8_t>& elf, const std::string& libraryName) const {
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@ -330,6 +498,25 @@ void ElfNidPatcher::PatchNids(std::vector<std::uint8_t>& elf, const std::string&
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oldToNewOffset.emplace_back(use.oldNameOffset, newOffset);
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}
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std::vector<std::uint32_t> preservedOffsets = CollectDynamicNameOffsets(elf, ehdr);
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const std::vector<std::uint32_t> verneedOffsets = CollectVerneedNameOffsets(elf, ehdr);
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preservedOffsets.insert(preservedOffsets.end(), verneedOffsets.begin(), verneedOffsets.end());
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for (const auto oldOffset : preservedOffsets) {
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const auto existing = std::find_if(
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oldToNewOffset.begin(), oldToNewOffset.end(),
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[&](const auto& entry) { return entry.first == oldOffset; }
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);
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if (existing != oldToNewOffset.end()) continue;
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const std::string preservedValue = ReadCStr(origDynStr, oldOffset);
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const auto newOffset = static_cast<std::uint32_t>(newDynStr.size());
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newDynStr.insert(newDynStr.end(), preservedValue.begin(), preservedValue.end());
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newDynStr.push_back(0u);
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oldToNewOffset.emplace_back(oldOffset, newOffset);
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}
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if (newDynStr.size() > dynStrSize) {
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throw std::runtime_error(
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"rebuilt .dynstr (" + std::to_string(newDynStr.size()) + " bytes) exceeds original section size (" +
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@ -356,6 +543,9 @@ void ElfNidPatcher::PatchNids(std::vector<std::uint8_t>& elf, const std::string&
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std::memcpy(elf.data() + dynStrOffset, newDynStr.data(), newDynStr.size());
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RemapDynamicNeededOffsets(elf, ehdr, oldToNewOffset);
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RemapVerneedOffsets(elf, ehdr, oldToNewOffset);
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if (gnuHashOffset != 0u) {
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const auto bucketCount = Read<std::uint32_t>(elf, gnuHashOffset);
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std::vector<std::uint32_t> oldToNewIndex(symCount);
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