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LibELF+Userland: Enable RELRO for all userland executables :^)

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The dynamic loader will now mark RELRO segments read-only after
performing relocations. This is pretty cool!

Note that this only applies to main executables so far,.
RELRO support for shared libraries will require some reorganizing
of the dynamic loader.
This commit is contained in:
Andreas Kling 2021-02-18 18:43:20 +01:00
parent 0d3866e84c
commit fa4c249425
Notes: sideshowbarker 2024-07-18 22:09:29 +09:00
4 changed files with 32 additions and 2 deletions
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25
Userland/Libraries/LibELF/DynamicLoader.cpp
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@ -234,6 +234,20 @@ RefPtr<DynamicObject> DynamicLoader::load_stage_3(unsigned flags, size_t total_t
return nullptr;
}
if (m_relro_segment_size) {
if (mprotect(m_relro_segment_address.as_ptr(), m_relro_segment_size, PROT_READ) < 0) {
perror("mprotect .relro: PROT_READ");
return nullptr;
}
#if __serenity__
if (set_mmap_name(m_relro_segment_address.as_ptr(), m_relro_segment_size, String::formatted("{}: .relro", m_filename).characters()) < 0) {
perror("set_mmap_name .relro");
return nullptr;
}
#endif
}
call_object_init_functions();
dbgln_if(DYNAMIC_LOAD_DEBUG, "Loaded {}", m_filename);
@ -255,11 +269,12 @@ void DynamicLoader::load_program_headers()
Optional<ProgramHeaderRegion> text_region;
Optional<ProgramHeaderRegion> data_region;
Optional<ProgramHeaderRegion> tls_region;
Optional<ProgramHeaderRegion> relro_region;
VirtualAddress dynamic_region_desired_vaddr;
m_elf_image.for_each_program_header([&](const Image::ProgramHeader& program_header) {
ProgramHeaderRegion region;
ProgramHeaderRegion region {};
region.set_program_header(program_header.raw_header());
if (region.is_tls_template()) {
ASSERT(!tls_region.has_value());
@ -274,6 +289,9 @@ void DynamicLoader::load_program_headers()
}
} else if (region.is_dynamic()) {
dynamic_region_desired_vaddr = region.desired_load_address();
} else if (region.is_relro()) {
ASSERT(!relro_region.has_value());
relro_region = region;
}
return IterationDecision::Continue;
});
@ -336,6 +354,11 @@ void DynamicLoader::load_program_headers()
m_text_segment_size = text_segment_size;
m_text_segment_load_address = VirtualAddress { (FlatPtr)text_segment_begin };
if (relro_region.has_value()) {
m_relro_segment_size = relro_region->size_in_memory();
m_relro_segment_address = m_text_segment_load_address.offset(relro_region->desired_load_address().get());
}
if (m_elf_image.is_dynamic())
m_dynamic_section_address = dynamic_region_desired_vaddr.offset(m_text_segment_load_address.get());
else