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Use segments instead of sections for calculating which offset to write,

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I noticed that the implementation is noth precise although it worked.
and instead of using the sections to identify memory addresses of
DT_DEBUG. I used segements
This commit is contained in:
oddcoder
2020-05-03 12:33:55 +02:00
parent 1182d12006
commit 67be05d3a3
1 changed files with 28 additions and 21 deletions
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src/ld_so/linker.rs
+28 -21
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@@ -689,29 +689,36 @@ impl Linker {
}
}
// overwrite DT_DEBUG if exist in .dynamic section
for section in &elf.section_headers {
// we won't bother with half corrupted elfs.
let name = elf.shdr_strtab.get(section.sh_name).unwrap().unwrap();
if name != ".dynamic" {
continue;
// overwrite DT_DEBUG if exist in DYNAMIC segment
// first we identify the location of DYNAMIC segment
let mut dyn_start = None;
let mut debug_start = None;
for ph in elf.program_headers.iter() {
if ph.p_type == program_header::PT_DYNAMIC {
dyn_start = Some(ph.p_vaddr as usize);
}
let mmap = match self.mmaps.get_mut(*elf_name) {
Some(some) => some,
None => continue,
};
let dyn_start = section.sh_addr as usize;
let bytes: [u8; size_of::<Dyn>() / 2] =
unsafe { transmute((&_r_debug) as *const RTLDDebug as usize) };
if let Some(dynamic) = elf.dynamic.as_ref() {
let mut i = 0;
for entry in &dynamic.dyns {
if entry.d_tag == DT_DEBUG {
let start = dyn_start + i * size_of::<Dyn>() + size_of::<Dyn>() / 2;
mmap[start..start + size_of::<Dyn>() / 2].clone_from_slice(&bytes);
}
i += 1;
}
// next we identify the location of DT_DEBUG in .dynamic section
if let Some(dynamic) = elf.dynamic.as_ref() {
let mut i = 0;
for entry in &dynamic.dyns {
if entry.d_tag == DT_DEBUG {
debug_start = Some(i as usize);
break;
}
i += 1;
}
}
if let Some(dyn_start_addr) = dyn_start {
if let Some(i) = debug_start {
let mmap = match self.mmaps.get_mut(*elf_name) {
Some(some) => some,
None => continue,
};
let bytes: [u8; size_of::<Dyn>() / 2] =
unsafe { transmute((&_r_debug) as *const RTLDDebug as usize) };
let start = dyn_start_addr + i * size_of::<Dyn>() + size_of::<Dyn>() / 2;
mmap[start..start + size_of::<Dyn>() / 2].clone_from_slice(&bytes);
}
}