Skip to content

Commit

Permalink
add a permissive feature
Browse files Browse the repository at this point in the history 
The permissive feature will make allow a more "relaxed" parsing of
files, making fewer checks and defaulting to 0 if EoF is found.
  • Loading branch information
@rbran
rbran committed Jan 9, 2025
1 parent 1743e1c commit b99ce5f
Show file tree
Hide file tree
Showing 12 changed files with 297 additions and 118 deletions.
4 changes: 4 additions & 0 deletions Cargo.toml
View file
Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,10 @@ flate2 = "1.0.31"
serde = { version = "1.0", features = ["derive"] }
num_enum = "0.7.3"

[features]
default = []
permissive = []

[[bin]]
name = "idb-tools"
path = "src/tools/tools.rs"
130 changes: 113 additions & 17 deletions src/ida_reader.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -43,9 +43,12 @@ pub trait IdaUnpack: IdaGenericUnpack {
if self.is_64() {
let start = self.unpack_dq()?;
let len = self.unpack_dq()?;
#[cfg(not(feature = "permissive"))]
let end = start
.checked_add(len)
.ok_or_else(|| anyhow!("Function range overflows"))?;
#[cfg(feature = "permissive")]
let end = start.saturating_add(len);
Ok(start..end)
} else {
let start = self.unpack_dd_ext_max()?;
Expand All @@ -54,7 +57,10 @@ pub trait IdaUnpack: IdaGenericUnpack {
let end = match start.checked_add(len.into()) {
Some(0xFFFF_FFFF) => u64::MAX,
Some(value) => value,
#[cfg(not(feature = "permissive"))]
None => return Err(anyhow!("Function range overflows")),
#[cfg(feature = "permissive")]
None => u64::MAX,
};
Ok(start..end)
}
Expand Down Expand Up @@ -172,11 +178,14 @@ pub trait IdaGenericBufUnpack: IdaGenericUnpack + BufRead {
let mut nelem = 0;
// TODO check no more then 9 bytes are read
loop {
let Some(typ) = self.fill_buf()?.first().copied() else {
let Some(typ) = self.peek_u8()? else {
#[cfg(not(feature = "permissive"))]
return Err(anyhow!(std::io::Error::new(
std::io::ErrorKind::UnexpectedEof,
"Unexpected EoF on DA"
)));
#[cfg(feature = "permissive")]
return Ok((nelem, base));
};
if typ & 0x80 == 0 {
break;
Expand All @@ -192,11 +201,14 @@ pub trait IdaGenericBufUnpack: IdaGenericUnpack + BufRead {
}
nelem = (z >> 4) & 7;
loop {
let Some(y) = self.fill_buf()?.first().copied() else {
let Some(y) = self.peek_u8()? else {
#[cfg(not(feature = "permissive"))]
return Err(anyhow!(std::io::Error::new(
std::io::ErrorKind::UnexpectedEof,
"Unexpected EoF on DA"
)));
#[cfg(feature = "permissive")]
return Ok((nelem, base));
};
if (y & 0x80) == 0 {
break;
Expand All @@ -218,7 +230,13 @@ pub trait IdaGenericBufUnpack: IdaGenericUnpack + BufRead {
let mut buf = vec![];
self.read_until(b'\x00', &mut buf)?;
// last char need to be \x00 or we found a EoF
ensure!(buf.pop() == Some(b'\x00'), "Unexpected EoF on CStr");
if let Some(b'\x00') = buf.last() {
let _ = buf.pop(); // remove the \x00 from the end
} else {
// found EOF, aka could not find the \x00 for the string end
#[cfg(not(feature = "permissive"))]
return Err(anyhow!("Unexpected EoF on CStr"));
}
Ok(buf)
}

Expand Down Expand Up @@ -249,6 +267,7 @@ pub trait IdaGenericBufUnpack: IdaGenericUnpack + BufRead {
if (start_value >> bit) & 1 != 0 {
let value = self.read_u8()?;
// TODO is this an error or expect possible value?
#[cfg(not(feature = "permissive"))]
ensure!(value != 0);
acc |= (value as u64) << byte;
}
Expand Down Expand Up @@ -301,6 +320,13 @@ pub trait IdaGenericUnpack: Read {
Ok(data[0])
}

#[cfg(feature = "permissive")]
fn read_u8_or_nothing(&mut self) -> Result<Option<u8>> {
let mut data = [0; 1];
let read = self.read_exact_or_nothing(&mut data)?;
Ok((read == data.len()).then_some(data[0]))
}

fn read_u16(&mut self) -> Result<u16> {
let mut data = [0; 2];
self.read_exact(&mut data)?;
Expand Down Expand Up @@ -339,23 +365,41 @@ pub trait IdaGenericUnpack: Read {
// NOTE: the original implementation never fails, if input hit EoF it a partial result or 0
/// Reads 1 to 3 bytes.
fn unpack_dw(&mut self) -> Result<u16> {
let b1: u8 = bincode::deserialize_from(&mut *self)?;
#[cfg(not(feature = "permissive"))]
let b1 = self.read_u8()?;
#[cfg(feature = "permissive")]
let Some(b1) = self.read_u8_or_nothing()?
else {
return Ok(0);
};
match b1 {
// 7 bit value
// [0xxx xxxx]
0x00..=0x7F => Ok(b1.into()),
// 14 bits value
// [10xx xxxx] xxxx xxxx
0x80..=0xBF => {
let lo: u8 = bincode::deserialize_from(&mut *self)?;
#[cfg(not(feature = "permissive"))]
let lo = self.read_u8()?;
#[cfg(feature = "permissive")]
let lo = self.read_u8_or_nothing()?.unwrap_or(0);
Ok(u16::from_be_bytes([b1 & 0x3F, lo]))
}
// 16 bits value
// [11XX XXXX] xxxx xxxx xxxx xxxx
0xC0..=0xFF => {
// NOTE first byte 6 bits seems to be ignored
//ensure!(header != 0xC0 && header != 0xFF);
Ok(u16::from_be_bytes(bincode::deserialize_from(&mut *self)?))
#[cfg(not(feature = "permissive"))]
let (lo, hi) = (self.read_u8()?, self.read_u8()?);

#[cfg(feature = "permissive")]
let (lo, hi) = (
self.read_u8_or_nothing()?.unwrap_or(0),
self.read_u8_or_nothing()?.unwrap_or(0),
);

Ok(u16::from_be_bytes([lo, hi]))
}
}
}
Expand All @@ -364,21 +408,34 @@ pub trait IdaGenericUnpack: Read {
// NOTE the orignal implementation never fails, if input hit EoF it a partial result or 0
/// Reads 1 to 5 bytes.
fn unpack_dd(&mut self) -> Result<u32> {
let b1: u8 = bincode::deserialize_from(&mut *self)?;
#[cfg(not(feature = "permissive"))]
let b1 = self.read_u8()?;
#[cfg(feature = "permissive")]
let Some(b1) = self.read_u8_or_nothing()?
else {
return Ok(0);
};
match b1 {
// 7 bit value
// [0xxx xxxx]
0x00..=0x7F => Ok(b1.into()),
// 14 bits value
// [10xx xxxx] xxxx xxxx
0x80..=0xBF => {
let lo: u8 = bincode::deserialize_from(&mut *self)?;
#[cfg(not(feature = "permissive"))]
let lo = self.read_u8()?;
#[cfg(feature = "permissive")]
let lo = self.read_u8_or_nothing()?.unwrap_or(0);
Ok(u32::from_be_bytes([0, 0, b1 & 0x3F, lo]))
}
// 29 bit value:
// [110x xxxx] xxxx xxxx xxxx xxxx xxxx xxxx
0xC0..=0xDF => {
let bytes: [u8; 3] = bincode::deserialize_from(&mut *self)?;
let mut bytes: [u8; 3] = [0; 3];
#[cfg(not(feature = "permissive"))]
self.read_exact(&mut bytes)?;
#[cfg(feature = "permissive")]
let _size = self.read_exact_or_nothing(&mut bytes)?;
Ok(u32::from_be_bytes([
b1 & 0x1F,
bytes[0],
Expand All @@ -391,7 +448,12 @@ pub trait IdaGenericUnpack: Read {
0xE0..=0xFF => {
// NOTE first byte 5 bits seems to be ignored
//ensure!(header != 0xE0 && header != 0xFF);
Ok(u32::from_be_bytes(bincode::deserialize_from(&mut *self)?))
let mut bytes: [u8; 4] = [0; 4];
#[cfg(not(feature = "permissive"))]
self.read_exact(&mut bytes)?;
#[cfg(feature = "permissive")]
let _size = self.read_exact_or_nothing(&mut bytes)?;
Ok(u32::from_be_bytes(bytes))
}
}
}
Expand All @@ -418,14 +480,20 @@ pub trait IdaGenericUnpack: Read {
fn unpack_ds(&mut self) -> Result<Vec<u8>> {
let len = self.unpack_dd()?;
let mut result = vec![0; len.try_into()?];
#[cfg(not(feature = "permissive"))]
self.read_exact(&mut result)?;
#[cfg(feature = "permissive")]
let _size = self.read_exact_or_nothing(&mut result)?;
Ok(result)
}

fn unpack_dt_bytes(&mut self) -> Result<Vec<u8>> {
let buf_len = self.read_dt()?;
let mut buf = vec![0; buf_len.into()];
#[cfg(not(feature = "permissive"))]
self.read_exact(&mut buf)?;
#[cfg(feature = "permissive")]
let _size = self.read_exact_or_nothing(&mut buf)?;
Ok(buf)
}

Expand All @@ -437,13 +505,19 @@ pub trait IdaGenericUnpack: Read {
// InnerRef fb47f2c2-3c08-4d40-b7ab-3c7736dce31d 0x48cdb0
let mut acc: u32 = 0;
for _ in 0..5 {
let b: u32 = self.read_u8()?.into();
#[cfg(not(feature = "permissive"))]
let b = self.read_u8()?;
#[cfg(feature = "permissive")]
let Some(b) = self.read_u8_or_nothing()?
else {
return Ok(acc);
};
if b & 0x80 == 0 {
acc = (b & 0x3F) | (acc << 6);
acc = (b & 0x3F) as u32 | (acc << 6);
return Ok(acc);
}

acc = (acc << 7) | (b & 0x7F);
acc = (acc << 7) | (b & 0x7F) as u32;
}
Err(anyhow!("Can't find the end of DE"))
}
Expand All @@ -454,12 +528,19 @@ pub trait IdaGenericUnpack: Read {
fn read_dt(&mut self) -> Result<u16> {
// InnerRef fb47f2c2-3c08-4d40-b7ab-3c7736dce31d 0x48cd60
let value = match self.read_u8()? {
#[cfg(not(feature = "permissive"))]
0 => return Err(anyhow!("DT can't have 0 value")),
#[cfg(feature = "permissive")]
0 => return Ok(0),
//SEG = 2
value @ 0x80.. => {
let inter: u16 = self.read_u8()?.into();
#[cfg(not(feature = "permissive"))]
let inter = self.read_u8()?;
#[cfg(feature = "permissive")]
let inter = self.read_u8_or_nothing()?.unwrap_or(0);
#[cfg(not(feature = "permissive"))]
ensure!(inter != 0, "DT can't have a following 0 value");
value as u16 & 0x7F | inter << 7
value as u16 & 0x7F | (inter as u16) << 7
}
//SEG = 1
value @ ..=0x7F => value.into(),
Expand Down Expand Up @@ -498,7 +579,16 @@ pub trait IdaGenericUnpack: Read {
// InnerRef fb47f2c2-3c08-4d40-b7ab-3c7736dce31d 0x452830
fn read_type_attribute(&mut self) -> Result<TypeAttribute> {
use crate::til::flag::tattr_ext::*;
let byte0: u8 = self.read_u8()?;
#[cfg(not(feature = "permissive"))]
let byte0 = self.read_u8()?;
#[cfg(feature = "permissive")]
let Some(byte0) = self.read_u8_or_nothing()?
else {
return Ok(TypeAttribute {
tattr: 0,
extended: None,
});
};
let mut tattr = 0;
if byte0 != 0xfe {
tattr = ((byte0 as u16 & 1) | ((byte0 as u16 >> 3) & 6)) + 1;
Expand All @@ -508,7 +598,13 @@ pub trait IdaGenericUnpack: Read {
let mut shift = 0;
// TODO limit the loop to only 0..n
loop {
let next_byte: u8 = self.read_u8()?;
#[cfg(not(feature = "permissive"))]
let next_byte = self.read_u8()?;
#[cfg(feature = "permissive")]
let Some(next_byte) = self.read_u8_or_nothing()?
else {
break;
};
ensure!(
next_byte != 0,
"Failed to parse TypeAttribute, byte is zero"
Expand Down
Loading

0 comments on commit b99ce5f

Please sign in to comment.