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Featurize rw reject #243

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Featurize rw reject #243

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32 changes: 18 additions & 14 deletions src/elf.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -378,7 +378,7 @@ impl<E: UserDefinedError, I: InstructionMeter> Executable<E, I> {
let elf = Elf::parse(bytes)?;
let mut elf_bytes = AlignedMemory::new_with_data(bytes, ebpf::HOST_ALIGN);

Self::validate(&elf, elf_bytes.as_slice())?;
Self::validate(&elf, elf_bytes.as_slice(), config.reject_all_rw)?;

// calculate the text section info
let text_section = Self::get_section(&elf, ".text")?;
Expand Down Expand Up @@ -536,7 +536,7 @@ impl<E: UserDefinedError, I: InstructionMeter> Executable<E, I> {
}

/// Validates the ELF
pub fn validate(elf: &Elf, elf_bytes: &[u8]) -> Result<(), ElfError> {
pub fn validate(elf: &Elf, elf_bytes: &[u8], reject_all_rw: bool) -> Result<(), ElfError> {
if elf.header.e_ident[EI_CLASS] != ELFCLASS64 {
return Err(ElfError::WrongClass);
}
Expand Down Expand Up @@ -570,7 +570,11 @@ impl<E: UserDefinedError, I: InstructionMeter> Executable<E, I> {

for section_header in elf.section_headers.iter() {
if let Some(this_name) = elf.shdr_strtab.get_at(section_header.sh_name) {
if this_name.starts_with(".bss") {
if reject_all_rw {
if this_name.starts_with(".bss") {
return Err(ElfError::BssNotSupported);
}
} else if this_name == ".bss" {
return Err(ElfError::BssNotSupported);
}
}
Expand Down Expand Up @@ -863,27 +867,27 @@ mod test {
let mut parsed_elf = Elf::parse(&bytes).unwrap();
let elf_bytes = bytes.to_vec();

ElfExecutable::validate(&parsed_elf, &elf_bytes).expect("validation failed");
ElfExecutable::validate(&parsed_elf, &elf_bytes, true).expect("validation failed");
parsed_elf.header.e_ident[EI_CLASS] = ELFCLASS32;
ElfExecutable::validate(&parsed_elf, &elf_bytes).expect_err("allowed bad class");
ElfExecutable::validate(&parsed_elf, &elf_bytes, true).expect_err("allowed bad class");
parsed_elf.header.e_ident[EI_CLASS] = ELFCLASS64;
ElfExecutable::validate(&parsed_elf, &elf_bytes).expect("validation failed");
ElfExecutable::validate(&parsed_elf, &elf_bytes, true).expect("validation failed");
parsed_elf.header.e_ident[EI_DATA] = ELFDATA2MSB;
ElfExecutable::validate(&parsed_elf, &elf_bytes).expect_err("allowed big endian");
ElfExecutable::validate(&parsed_elf, &elf_bytes, true).expect_err("allowed big endian");
parsed_elf.header.e_ident[EI_DATA] = ELFDATA2LSB;
ElfExecutable::validate(&parsed_elf, &elf_bytes).expect("validation failed");
ElfExecutable::validate(&parsed_elf, &elf_bytes, true).expect("validation failed");
parsed_elf.header.e_ident[EI_OSABI] = 1;
ElfExecutable::validate(&parsed_elf, &elf_bytes).expect_err("allowed wrong abi");
ElfExecutable::validate(&parsed_elf, &elf_bytes, true).expect_err("allowed wrong abi");
parsed_elf.header.e_ident[EI_OSABI] = ELFOSABI_NONE;
ElfExecutable::validate(&parsed_elf, &elf_bytes).expect("validation failed");
ElfExecutable::validate(&parsed_elf, &elf_bytes, true).expect("validation failed");
parsed_elf.header.e_machine = EM_QDSP6;
ElfExecutable::validate(&parsed_elf, &elf_bytes).expect_err("allowed wrong machine");
ElfExecutable::validate(&parsed_elf, &elf_bytes, true).expect_err("allowed wrong machine");
parsed_elf.header.e_machine = EM_BPF;
ElfExecutable::validate(&parsed_elf, &elf_bytes).expect("validation failed");
ElfExecutable::validate(&parsed_elf, &elf_bytes, true).expect("validation failed");
parsed_elf.header.e_type = ET_REL;
ElfExecutable::validate(&parsed_elf, &elf_bytes).expect_err("allowed wrong type");
ElfExecutable::validate(&parsed_elf, &elf_bytes, true).expect_err("allowed wrong type");
parsed_elf.header.e_type = ET_DYN;
ElfExecutable::validate(&parsed_elf, &elf_bytes).expect("validation failed");
ElfExecutable::validate(&parsed_elf, &elf_bytes, true).expect("validation failed");
}

#[test]
Expand Down
3 changes: 3 additions & 0 deletions src/vm.rs
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Expand Up @@ -204,6 +204,8 @@ pub struct Config {
pub verify_mul64_imm_nonzero: bool,
/// Feature flag for the SHIFT_IMM >= 32 verification check
pub verify_shift32_imm: bool,
/// Feature flag for rejecting all rw sections in the ELF
pub reject_all_rw: bool,
}
impl Default for Config {
fn default() -> Self {
Expand All @@ -222,6 +224,7 @@ impl Default for Config {
encrypt_environment_registers: true,
verify_mul64_imm_nonzero: false,
verify_shift32_imm: false,
reject_all_rw: false,
}
}
}
Expand Down