From 0632802ebaa962c9cdeea3cf06ce011e9450acc1 Mon Sep 17 00:00:00 2001 From: Omer Ben-Amram Date: Tue, 4 Jun 2019 16:07:36 +0300 Subject: hard error on invalid input --- src/bin/mft_dump.rs | 2 +- src/entry.rs | 51 +++++++++++++++++++++++++++++++++++++++++++++++---- src/err.rs | 5 ++++- 3 files changed, 52 insertions(+), 6 deletions(-) diff --git a/src/bin/mft_dump.rs b/src/bin/mft_dump.rs index d24db4f..915abbe 100644 --- a/src/bin/mft_dump.rs +++ b/src/bin/mft_dump.rs @@ -429,7 +429,7 @@ fn main() { match app.run() { Ok(()) => {} Err(e) => { - eprintln!("A runtime error has occurred {}", &e); + eprintln!("A runtime error has occurred: {}", &e); exit(1); } }; diff --git a/src/entry.rs b/src/entry.rs index 4ee46fc..4feee46 100644 --- a/src/entry.rs +++ b/src/entry.rs @@ -22,6 +22,10 @@ use std::io::{Cursor, Seek}; const SEQUENCE_NUMBER_STRIDE: usize = 512; +const ZERO_HEADER: &'static [u8; 4] = b"\x00\x00\x00\x00"; +const BAAD_HEADER: &'static [u8; 4] = b"BAAD"; +const FILE_HEADER: &'static [u8; 4] = b"FILE"; + #[derive(Debug, Clone)] pub struct MftEntry { pub header: EntryHeader, @@ -47,7 +51,7 @@ impl ser::Serialize for MftEntry { pub struct EntryHeader { /// MULTI_SECTOR_HEADER /// The signature. This value is a convenience to the user. - /// This is either "BAAD" or "FILE" + /// This is either "BAAD", "FILE", or "\x00\x00\x00\x00" pub signature: [u8; 4], /// The offset to the update sequence array, from the start of this structure. /// The update sequence array must end before the last USHORT value in the first sector. @@ -92,14 +96,26 @@ impl EntryHeader { let mut signature = [0; 4]; reader.read_exact(&mut signature)?; - // Empty entry + let mut header_is_valid = false; + + for header in &[FILE_HEADER, BAAD_HEADER, ZERO_HEADER] { + if signature == **header { + header_is_valid = true; + break; + } + } + ensure!( - &signature != b"\x00\x00\x00\x00", + header_is_valid, err::InvalidEntrySignature { bad_sig: signature.to_vec() } ); + if signature == *ZERO_HEADER { + return Ok(Self::zero()); + } + let usa_offset = reader.read_u16::()?; let usa_size = reader.read_u16::()?; let logfile_sequence_number = reader.read_u64::()?; @@ -131,6 +147,31 @@ impl EntryHeader { record_number: entry_id, }) } + + pub fn is_valid(&self) -> bool { + self.signature == *FILE_HEADER + } + + pub fn zero() -> Self { + EntryHeader { + signature: *ZERO_HEADER, + usa_offset: 0, + usa_size: 0, + metadata_transaction_journal: 0, + sequence: 0, + hard_link_count: 0, + first_attribute_record_offset: 0, + flags: EntryFlags::from_bits_truncate(0), + used_entry_size: 0, + total_entry_size: 0, + base_reference: MftReference { + entry: 0, + sequence: 0, + }, + first_attribute_id: 0, + record_number: 0, + } + } } impl MftEntry { @@ -143,7 +184,9 @@ impl MftEntry { let entry_header = EntryHeader::from_reader(&mut cursor, entry_number)?; trace!("Number of sectors: {:#?}", entry_header); - Self::apply_fixups(&entry_header, &mut buffer)?; + if entry_header.is_valid() { + Self::apply_fixups(&entry_header, &mut buffer)?; + } Ok(MftEntry { header: entry_header, diff --git a/src/err.rs b/src/err.rs index bfcad21..78076fb 100644 --- a/src/err.rs +++ b/src/err.rs @@ -19,7 +19,10 @@ pub enum Error { }, #[snafu(display("Error while decoding name in filename attribute"))] InvalidFilename, - #[snafu(display("Bad signature: {:x?}", bad_sig))] + #[snafu(display( + "Bad signature: {:x?}, expected one of [b\"FILE\", b\"BAAD\", b\"0000\"]", + bad_sig + ))] InvalidEntrySignature { bad_sig: Vec }, #[snafu(display("Unknown `AttributeType`: {:04X}", attribute_type))] UnknownAttributeType { attribute_type: u32 }, -- cgit v1.2.3 From 77491c9c1d3216ec5f320e2c42156a2d4f2b6dee Mon Sep 17 00:00:00 2001 From: Omer Ben-Amram Date: Tue, 4 Jun 2019 16:13:46 +0300 Subject: add a test --- src/entry.rs | 9 +-------- tests/test_cli.rs | 17 ++++++++++++++++- 2 files changed, 17 insertions(+), 9 deletions(-) diff --git a/src/entry.rs b/src/entry.rs index 4feee46..dade633 100644 --- a/src/entry.rs +++ b/src/entry.rs @@ -96,14 +96,7 @@ impl EntryHeader { let mut signature = [0; 4]; reader.read_exact(&mut signature)?; - let mut header_is_valid = false; - - for header in &[FILE_HEADER, BAAD_HEADER, ZERO_HEADER] { - if signature == **header { - header_is_valid = true; - break; - } - } + let header_is_valid = [FILE_HEADER, BAAD_HEADER, ZERO_HEADER].contains(&&signature); ensure!( header_is_valid, diff --git a/tests/test_cli.rs b/tests/test_cli.rs index b247ad5..3cac0f5 100644 --- a/tests/test_cli.rs +++ b/tests/test_cli.rs @@ -5,7 +5,7 @@ use fixtures::*; use assert_cmd::prelude::*; use std::fs; use std::fs::File; -use std::io::Read; +use std::io::{Read, Write}; use std::process::Command; use tempfile::tempdir; @@ -44,6 +44,21 @@ fn test_it_refuses_to_overwrite_directory() { cmd.assert().failure().code(1); } +#[test] +fn test_non_mft_file_is_error() { + let d = tempdir().unwrap(); + + let f = d.as_ref().join("test.out"); + + let mut file = File::create(&f).unwrap(); + file.write_all(b"I'm a file!").unwrap(); + + let mut cmd = Command::cargo_bin("mft_dump").expect("failed to find binary"); + cmd.args(&[f.to_str().unwrap()]); + + cmd.assert().failure().code(1); +} + #[test] fn test_it_exports_resident_streams() { let d = tempdir().unwrap(); -- cgit v1.2.3