diff options
Diffstat (limited to 'src/patchelf.h')
| -rw-r--r-- | src/patchelf.h | 153 |
1 files changed, 124 insertions, 29 deletions
diff --git a/src/patchelf.h b/src/patchelf.h index c3096ff..9fab18c 100644 --- a/src/patchelf.h +++ b/src/patchelf.h @@ -1,7 +1,37 @@ +#include <map> +#include <memory> +#include <optional> +#include <set> +#include <stdexcept> +#include <string> +#include <vector> + +#include "elf.h" + using FileContents = std::shared_ptr<std::vector<unsigned char>>; -#define ElfFileParams class Elf_Ehdr, class Elf_Phdr, class Elf_Shdr, class Elf_Addr, class Elf_Off, class Elf_Dyn, class Elf_Sym, class Elf_Verneed, class Elf_Versym -#define ElfFileParamNames Elf_Ehdr, Elf_Phdr, Elf_Shdr, Elf_Addr, Elf_Off, Elf_Dyn, Elf_Sym, Elf_Verneed, Elf_Versym +#define ElfFileParams class Elf_Ehdr, class Elf_Phdr, class Elf_Shdr, class Elf_Addr, class Elf_Off, class Elf_Dyn, class Elf_Sym, class Elf_Verneed, class Elf_Versym, class Elf_Rel, class Elf_Rela, unsigned ElfClass +#define ElfFileParamNames Elf_Ehdr, Elf_Phdr, Elf_Shdr, Elf_Addr, Elf_Off, Elf_Dyn, Elf_Sym, Elf_Verneed, Elf_Versym, Elf_Rel, Elf_Rela, ElfClass + +template<class T> +struct span +{ + explicit span(T* d = {}, size_t l = {}) : data(d), len(l) {} + span(T* from, T* to) : data(from), len(to-from) { assert(from <= to); } + T& operator[](std::size_t i) { checkRange(i); return data[i]; } + T* begin() { return data; } + T* end() { return data + len; } + auto size() const { return len; } + explicit operator bool() const { return size() > 0; } + +private: + void checkRange(std::size_t i) { + if (i >= size()) throw std::out_of_range("error: Span access out of range."); + } + + T* data; + size_t len; +}; template<ElfFileParams> class ElfFile @@ -30,14 +60,14 @@ private: /* Align on 4 or 8 bytes boundaries on 32- or 64-bit platforms respectively. */ - size_t sectionAlignment = sizeof(Elf_Off); + static constexpr size_t sectionAlignment = sizeof(Elf_Off); std::vector<SectionName> sectionsByOldIndex; public: explicit ElfFile(FileContents fileContents); - bool isChanged() + [[nodiscard]] bool isChanged() const noexcept { return changed; } @@ -46,8 +76,8 @@ private: struct CompPhdr { - ElfFile * elfFile; - bool operator ()(const Elf_Phdr & x, const Elf_Phdr & y) + const ElfFile * elfFile; + bool operator ()(const Elf_Phdr & x, const Elf_Phdr & y) const noexcept { // A PHDR comes before everything else. if (elfFile->rdi(y.p_type) == PT_PHDR) return false; @@ -58,39 +88,39 @@ private: } }; - friend struct CompPhdr; - void sortPhdrs(); struct CompShdr { - ElfFile * elfFile; - bool operator ()(const Elf_Shdr & x, const Elf_Shdr & y) + const ElfFile * elfFile; + bool operator ()(const Elf_Shdr & x, const Elf_Shdr & y) const noexcept { return elfFile->rdi(x.sh_offset) < elfFile->rdi(y.sh_offset); } }; - friend struct CompShdr; - - unsigned int getPageSize() const; + [[nodiscard]] unsigned int getPageSize() const noexcept; void sortShdrs(); void shiftFile(unsigned int extraPages, size_t sizeOffset, size_t extraBytes); - std::string getSectionName(const Elf_Shdr & shdr) const; + [[nodiscard]] std::string getSectionName(const Elf_Shdr & shdr) const; + + const Elf_Shdr & findSectionHeader(const SectionName & sectionName) const; - Elf_Shdr & findSectionHeader(const SectionName & sectionName); + [[nodiscard]] std::optional<std::reference_wrapper<const Elf_Shdr>> tryFindSectionHeader(const SectionName & sectionName) const; - std::optional<std::reference_wrapper<Elf_Shdr>> tryFindSectionHeader(const SectionName & sectionName); + template<class T> span<T> getSectionSpan(const Elf_Shdr & shdr) const; + template<class T> span<T> getSectionSpan(const SectionName & sectionName); + template<class T> span<T> tryGetSectionSpan(const SectionName & sectionName); - unsigned int getSectionIndex(const SectionName & sectionName); + [[nodiscard]] unsigned int getSectionIndex(const SectionName & sectionName) const; std::string & replaceSection(const SectionName & sectionName, unsigned int size); - bool haveReplacedSection(const SectionName & sectionName) const; + [[nodiscard]] bool haveReplacedSection(const SectionName & sectionName) const; void writeReplacedSections(Elf_Off & curOff, Elf_Addr startAddr, Elf_Off startOffset); @@ -107,7 +137,7 @@ public: void rewriteSections(bool force = false); - std::string getInterpreter(); + [[nodiscard]] std::string getInterpreter() const; typedef enum { printOsAbi, replaceOsAbi } osAbiMode; @@ -131,12 +161,14 @@ public: void replaceNeeded(const std::map<std::string, std::string> & libs); - void printNeededLibs() /* should be const */; + void printNeededLibs() const; void noDefaultLib(); void addDebugTag(); + void renameDynamicSymbols(const std::unordered_map<std::string_view, std::string>&); + void clearSymbolVersions(const std::set<std::string> & syms); enum class ExecstackMode { print, set, clear }; @@ -144,26 +176,89 @@ public: void modifyExecstack(ExecstackMode op); private: + struct GnuHashTable { + using BloomWord = Elf_Addr; + struct Header { + uint32_t numBuckets, symndx, maskwords, shift2; + } m_hdr; + span<BloomWord> m_bloomFilters; + span<uint32_t> m_buckets, m_table; + }; + GnuHashTable parseGnuHashTable(span<char> gh); + + struct HashTable { + struct Header { + uint32_t numBuckets, nchain; + } m_hdr; + span<uint32_t> m_buckets, m_chain; + }; + HashTable parseHashTable(span<char> gh); + + void rebuildGnuHashTable(span<char> strTab, span<Elf_Sym> dynsyms); + void rebuildHashTable(span<char> strTab, span<Elf_Sym> dynsyms); + + using Elf_Rel_Info = decltype(Elf_Rel::r_info); + + uint32_t rel_getSymId(const Elf_Rel_Info& info) const + { + if constexpr (std::is_same_v<Elf_Rel, Elf64_Rel>) + return ELF64_R_SYM(info); + else + return ELF32_R_SYM(info); + } + + Elf_Rel_Info rel_setSymId(Elf_Rel_Info info, uint32_t id) const + { + if constexpr (std::is_same_v<Elf_Rel, Elf64_Rel>) + { + constexpr Elf_Rel_Info idmask = (~Elf_Rel_Info()) << 32; + info = (info & ~idmask) | (Elf_Rel_Info(id) << 32); + } + else + { + constexpr Elf_Rel_Info idmask = (~Elf_Rel_Info()) << 8; + info = (info & ~idmask) | (Elf_Rel_Info(id) << 8); + } + return info; + } + + template<class ElfRelType, class RemapFn> + void changeRelocTableSymIds(const Elf_Shdr& shdr, RemapFn&& old2newSymId) + { + static_assert(std::is_same_v<ElfRelType, Elf_Rel> || std::is_same_v<ElfRelType, Elf_Rela>); + + for (auto& r : getSectionSpan<ElfRelType>(shdr)) + { + auto info = rdi(r.r_info); + auto oldSymIdx = rel_getSymId(info); + auto newSymIdx = old2newSymId(oldSymIdx); + if (newSymIdx != oldSymIdx) + wri(r.r_info, rel_setSymId(info, newSymIdx)); + } + } /* Convert an integer in big or little endian representation (as specified by the ELF header) to this platform's integer representation. */ template<class I> - I rdi(I i) const; + constexpr I rdi(I i) const noexcept; /* Convert back to the ELF representation. */ - template<class I> - I wri(I & t, unsigned long long i) const + template<class I, class U> + constexpr inline I wri(I & t, U i) const { - t = rdi((I) i); - return i; + I val = static_cast<I>(i); + if (static_cast<U>(val) != i) + throw std::runtime_error { "value truncation" }; + t = rdi(val); + return val; } - Elf_Ehdr *hdr() { - return (Elf_Ehdr *)fileContents->data(); + [[nodiscard]] Elf_Ehdr *hdr() noexcept { + return reinterpret_cast<Elf_Ehdr *>(fileContents->data()); } - const Elf_Ehdr *hdr() const { - return (const Elf_Ehdr *)fileContents->data(); + [[nodiscard]] const Elf_Ehdr *hdr() const noexcept { + return reinterpret_cast<const Elf_Ehdr *>(fileContents->data()); } }; |