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use {
crate::UndefinedSymbol,
byteorder::ReadBytesExt,
std::{ffi::CStr, os::raw::c_char},
};
#[repr(C)]
#[derive(Debug, Clone)]
struct Elf64_Verdef {
vd_version: u16,
vd_flags: u16,
vd_ndx: u16,
vd_cnt: u16,
vd_hash: u32,
vd_aux: u32,
vd_next: u32,
}
#[repr(C)]
#[derive(Debug, Clone)]
struct Elf64_Verneed {
vn_version: u16,
vn_cnt: u16,
vn_file: u32,
vn_aux: u32,
vn_next: u32,
}
#[repr(C)]
#[derive(Debug, Clone)]
struct Elf64_Vernaux {
vna_hash: u32,
vna_flags: u16,
vna_other: u16,
vna_name: u32,
vna_next: u32,
}
fn resolve_verneed(
verneed_entries: &[(Elf64_Verneed, Vec<Elf64_Vernaux>)],
names_data: &[u8],
versym: u16,
) -> (Option<String>, Option<String>) {
for (verneed, vernauxes) in verneed_entries {
for vernaux in vernauxes {
if vernaux.vna_other != versym {
continue;
}
let filename_ptr = unsafe { names_data.as_ptr().add(verneed.vn_file as usize) };
let filename = unsafe { CStr::from_ptr(filename_ptr as *const c_char) };
let depend_ptr = unsafe { names_data.as_ptr().add(vernaux.vna_name as usize) };
let depend = unsafe { CStr::from_ptr(depend_ptr as *const c_char) };
return (
Some(filename.to_string_lossy().into_owned()),
Some(depend.to_string_lossy().into_owned()),
);
}
}
(None, None)
}
#[allow(clippy::cast_ptr_alignment)]
pub fn find_undefined_elf_symbols(buffer: &[u8], elf: &goblin::elf::Elf) -> Vec<UndefinedSymbol> {
let mut verneed_entries: Vec<(Elf64_Verneed, Vec<Elf64_Vernaux>)> = Vec::new();
let mut versym: Vec<u16> = Vec::new();
let mut verneed_names_section: u32 = 0;
for section_header in &elf.section_headers {
match section_header.sh_type {
goblin::elf::section_header::SHT_GNU_VERSYM => {
let data: &[u8] = &buffer[section_header
.file_range()
.expect("SHT_GNU_VERSYM missing file range")];
let mut reader = std::io::Cursor::new(data);
while let Ok(value) = reader.read_u16::<byteorder::NativeEndian>() {
versym.push(value);
}
}
goblin::elf::section_header::SHT_GNU_VERNEED => {
verneed_names_section = section_header.sh_link;
let data: &[u8] = &buffer[section_header
.file_range()
.expect("SHT_GNU_VERNEED missing file range")];
let mut ptr = data.as_ptr();
for _ in 0..elf.dynamic.as_ref().unwrap().info.verneednum {
let record: Elf64_Verneed = unsafe { std::ptr::read(ptr as *const _) };
let next_record = unsafe { ptr.add(record.vn_next as usize) };
let mut vernaux: Vec<Elf64_Vernaux> = Vec::new();
ptr = unsafe { ptr.add(record.vn_aux as usize) };
for _ in 0..record.vn_cnt {
let aux: Elf64_Vernaux = unsafe { std::ptr::read(ptr as *const _) };
vernaux.push(aux.clone());
ptr = unsafe { ptr.add(aux.vna_next as usize) };
}
verneed_entries.push((record.clone(), vernaux));
ptr = next_record;
}
}
_ => {}
}
}
let dynstrtab = &elf.dynstrtab;
let verneed_names_data: &[u8] = &buffer[elf.section_headers[verneed_names_section as usize]
.file_range()
.expect("verneed names section missing file range")];
let mut res: Vec<UndefinedSymbol> = Vec::new();
let mut versym_iter = versym.iter();
for sym in elf.dynsyms.iter() {
let versym = *versym_iter.next().unwrap();
if sym.is_import() {
let name = dynstrtab.get_at(sym.st_name).unwrap();
res.push(if versym > 1 {
let (filename, version) =
resolve_verneed(&verneed_entries, verneed_names_data, versym);
UndefinedSymbol {
symbol: String::from(name),
filename,
version,
}
} else {
UndefinedSymbol {
symbol: String::from(name),
filename: None,
version: None,
}
});
}
}
res
}