forked from eden-emu/eden
68 lines
2.2 KiB
C++
68 lines
2.2 KiB
C++
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// SPDX-License-Identifier: BSD-2-Clause
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// Copyright © 2021 Billy Laws
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#include <initializer_list>
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#include <cstdint>
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#include <errno.h>
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#include <sys/stat.h>
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#include <sys/mman.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <link.h>
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#include <elf.h>
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#include "elf_soname_patcher.h"
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bool elf_soname_patch(const char *libPath, int targetFd, const char *sonamePatch) {
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struct stat libStat{};
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if (stat(libPath, &libStat))
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return false;
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if (ftruncate(targetFd, libStat.st_size) == -1)
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return false;
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// Map the memory so we can read our elf into it
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auto mappedLib{reinterpret_cast<uint8_t *>(mmap(nullptr, libStat.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, targetFd, 0))};
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if (!mappedLib)
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return false;
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int libFd{open(libPath, O_RDONLY)};
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if (libFd == false)
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return false;
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// Read lib elf into target file
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if (read(libFd, mappedLib, libStat.st_size) != libStat.st_size)
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return false;
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// No longer needed
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close(libFd);
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auto eHdr{reinterpret_cast<ElfW(Ehdr) *>(mappedLib)};
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auto sHdrEntries{reinterpret_cast<ElfW(Shdr) *>(mappedLib + eHdr->e_shoff)};
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// Iterate over section headers to find the .dynamic section
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for (ElfW(Half) i{}; i < eHdr->e_shnum; i++) {
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auto &sHdr{sHdrEntries[i]};
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if (sHdr.sh_type == SHT_DYNAMIC) {
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auto strTab{reinterpret_cast<char *>(mappedLib + sHdrEntries[sHdr.sh_link].sh_offset)};
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auto dynHdrEntries{reinterpret_cast<ElfW(Dyn) *>(mappedLib + sHdr.sh_offset)};
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// Iterate over .dynamic entries to find DT_SONAME
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for (ElfW(Xword) k{}; k < (sHdr.sh_size / sHdr.sh_entsize); k++) {
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auto &dynHdrEntry{dynHdrEntries[k]};
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if (dynHdrEntry.d_tag == DT_SONAME) {
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char *soname{strTab + dynHdrEntry.d_un.d_val};
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// Partially replace the old soname with the soname patch
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size_t charIdx{};
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for (; soname[charIdx] != 0 && sonamePatch[charIdx] != 0; charIdx++)
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soname[charIdx] = sonamePatch[charIdx];
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return true;
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}
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}
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}
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}
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return false;
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}
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