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DynamicLoader: map RO sections actually read only 

I was mapping everything RW as i did not have mprotect when I
implemented the dynamic loader.
This commit is contained in:
Bananymous 2026-02-04 23:21:06 +02:00
parent c304133224
commit 8fb2270ecf
1 changed files with 9 additions and 8 deletions
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13
userspace/programs/DynamicLoader/main.cpp
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@ -373,8 +373,6 @@ static void handle_copy_relocation(const LoadedElf& elf, const RelocT& reloc)
reinterpret_cast<void*>(src_elf->base + src_sym->st_value),
symbol.st_size
);
src_sym->st_value = (elf.base + reloc.r_offset) - src_elf->base;
}
template<typename RelocT> requires BAN::is_same_v<RelocT, ElfNativeRelocation> || BAN::is_same_v<RelocT, ElfNativeRelocationA>
@ -927,6 +925,8 @@ static bool can_load_elf(int fd, const ElfNativeFileHeader& file_header, uintptr
return true;
}
// FIXME: Don't map read-only sections as writable with DT_TEXTREL.
// Instead mprotect the areas writable during relocation.
static void load_program_header(const ElfNativeProgramHeader& program_header, int fd, bool needs_writable)
{
if (program_header.p_type != PT_LOAD)
@ -966,7 +966,7 @@ static void load_program_header(const ElfNativeProgramHeader& program_header, in
mmap_args.flags = MAP_PRIVATE | MAP_FIXED;
mmap_args.len = file_backed_size;
mmap_args.off = program_header.p_offset;
mmap_args.prot = prot | PROT_WRITE;
mmap_args.prot = prot | (needs_writable ? PROT_WRITE : 0);
if (auto ret = syscall(SYS_MMAP, &mmap_args); ret != static_cast<long>(program_header.p_vaddr))
print_error_and_exit("could not load program header", ret);
@ -1002,12 +1002,13 @@ static void load_program_header(const ElfNativeProgramHeader& program_header, in
0x00,
program_header.p_memsz - program_header.p_filesz
);
}
if (!(prot & PROT_WRITE) && !needs_writable)
{
// FIXME: Implement mprotect so PROT_WRITE can be removed
//syscall(SYS_MPROTECT, start_vaddr, length, prot);
if (auto ret = syscall(SYS_MPROTECT, program_header.p_vaddr + file_backed_size, program_header.p_memsz - file_backed_size, prot))
print_error_and_exit("failed to remove PROT_WRITE from mapped", ret);
print(STDDBG_FILENO, "dropped PROT_WRITE :nekocatwoah:");
}
}
}