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Apply relocations manually in DWARF parsing. #7487

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Apply relocations manually in DWARF parsing. #7487

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14 changes: 13 additions & 1 deletion Cargo.lock
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1 change: 1 addition & 0 deletions plugins/dwarf/shared/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -11,3 +11,4 @@ binaryninjacore-sys.workspace = true
gimli = "0.31"
zstd = "0.13.2"
thiserror = "2.0"
object = "0.36"
187 changes: 167 additions & 20 deletions plugins/dwarf/shared/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@
// limitations under the License.

use gimli::{EndianRcSlice, Endianity, RunTimeEndian, SectionId};
use object::{Object, ObjectSection, ObjectSymbol};

use binaryninja::{
binary_view::{BinaryView, BinaryViewBase, BinaryViewExt},
Expand Down Expand Up @@ -135,7 +136,7 @@ pub fn create_section_reader<'a, Endian: 'a + Endianity>(
};
// If the section has the compressed bit set
if (section_flags & 2048) != 0 {
// Get section, trim header, decompress, return
// Get section, trim header, decompress, and apply relocations before returning
let compressed_header_size = view.address_size() * 3;

let offset = section.start() + compressed_header_size as u64;
Expand All @@ -145,23 +146,26 @@ pub fn create_section_reader<'a, Endian: 'a + Endianity>(
let ch_type = endian.read_u32(&ch_type_vec);

if let Ok(buffer) = view.read_buffer(offset, len) {
match ch_type {
1 => {
return Ok(EndianRcSlice::new(
buffer.zlib_decompress().get_data().into(),
endian,
));
}
2 => {
return Ok(EndianRcSlice::new(
zstd::decode_all(buffer.get_data())?.as_slice().into(),
endian,
));
}
x => {
return Err(Error::UnknownCompressionMethod(x));
}
}
let mut decompressed = match ch_type {
1 => buffer.zlib_decompress().get_data().to_vec(),
2 => zstd::decode_all(buffer.get_data())?,
x => return Err(Error::UnknownCompressionMethod(x)),
};

let section_name_owned = section.name().to_string_lossy().into_owned();
let is_little =
matches!(view.default_endianness(), Endianness::LittleEndian);
apply_relocations_with_object(
view,
&section_name_owned,
&mut decompressed,
is_little,
);

return Ok(EndianRcSlice::new(
Rc::from(decompressed.into_boxed_slice()),
endian,
));
}
}
}
Expand All @@ -172,8 +176,12 @@ pub fn create_section_reader<'a, Endian: 'a + Endianity>(
if len == 0 {
Ok(EndianRcSlice::new(Rc::from([]), endian))
} else {
let mut data = view.read_vec(offset, len);
let section_name_owned = section.name().to_string_lossy().into_owned();
let is_little = matches!(view.default_endianness(), Endianness::LittleEndian);
apply_relocations_with_object(view, &section_name_owned, &mut data, is_little);
Ok(EndianRcSlice::new(
Rc::from(view.read_vec(offset, len).as_slice()),
Rc::from(data.into_boxed_slice()),
endian,
))
}
Expand All @@ -183,11 +191,150 @@ pub fn create_section_reader<'a, Endian: 'a + Endianity>(
"__{}",
&section_name[1..section_name.len().min(15)]
)) {
let mut data = view.read_vec(section.start(), section.len());
apply_relocations_with_object(
view,
section.name().to_string_lossy().as_ref(),
&mut data,
matches!(view.default_endianness(), Endianness::LittleEndian),
);
Ok(EndianRcSlice::new(
Rc::from(view.read_vec(section.start(), section.len()).as_slice()),
Rc::from(data.into_boxed_slice()),
endian,
))
} else {
Ok(EndianRcSlice::new(Rc::from([]), endian))
}
}

fn read_int(bytes: &[u8], is_little_endian: bool) -> u64 {
let mut value = 0u64;
if is_little_endian {
for (i, byte) in bytes.iter().enumerate() {
value |= (*byte as u64) << (i * 8);
}
} else {
for (i, byte) in bytes.iter().enumerate() {
value |= (*byte as u64) << (8 * (bytes.len() - 1 - i));
}
}
value
}

fn write_int(bytes: &mut [u8], value: u64, is_little_endian: bool) {
if is_little_endian {
for (i, byte) in bytes.iter_mut().enumerate() {
*byte = (value >> (i * 8)) as u8;
}
} else {
let len = bytes.len();
for (i, byte) in bytes.iter_mut().enumerate() {
let shift = 8 * (len - 1 - i);
*byte = (value >> shift) as u8;
}
}
}

fn apply_relocations_with_object(
view: &BinaryView,
section_name: &str,
data: &mut [u8],
is_little_endian: bool,
) -> bool {
let Some(file_bytes) = read_entire_view(view) else {
return false;
};

let Ok(file) = object::File::parse(&*file_bytes) else {
return false;
};

let Some(obj_section) = file.section_by_name(section_name) else {
return false;
};

let mut applied = false;

for (offset, relocation) in obj_section.relocations() {
let size_bits = relocation.size();
if size_bits == 0 {
continue;
}
let size = (size_bits / 8) as usize;
if size == 0 || size > 8 {
continue;
}

let offset = offset as usize;
if offset + size > data.len() {
continue;
}

let mut base = 0i128;
let mut target_section_name: Option<&str> = None;

match relocation.target() {
object::RelocationTarget::Symbol(symbol_index) => {
let Ok(symbol) = file.symbol_by_index(symbol_index) else {
continue;
};
if let Some(section_index) = symbol.section_index() {
let Ok(target_section) = file.section_by_index(section_index) else {
continue;
};
if let Ok(name) = target_section.name() {
target_section_name = Some(name);
}
base += target_section.address() as i128;
}
base += symbol.address() as i128;
}
object::RelocationTarget::Section(section_index) => {
let Ok(target_section) = file.section_by_index(section_index) else {
continue;
};
if let Ok(name) = target_section.name() {
target_section_name = Some(name);
}
base += target_section.address() as i128;
}
_ => {}
}

if let Some(name) = target_section_name {
if !is_debug_related_section(name) {
continue;
}
} else {
continue;
}

if relocation.kind() != object::RelocationKind::Absolute {
continue;
}

let _existing = read_int(&data[offset..offset + size], is_little_endian) as i128;
let addend = relocation.addend() as i128;
let value = base.wrapping_add(addend) as u64;
write_int(&mut data[offset..offset + size], value, is_little_endian);
applied = true;
}

applied
}

fn read_entire_view(view: &BinaryView) -> Option<Vec<u8>> {
let len = view.len();
if len == 0 || len > usize::MAX as u64 {
return None;
}
let data = view.read_vec(0, len as usize);
if data.len() as u64 != len {
return None;
}
Some(data)
}

fn is_debug_related_section(name: &str) -> bool {
name.starts_with(".debug") || name.starts_with(".zdebug")
}
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