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macro_rules! elf_section_header {
($size:ident) => {
// XXX: Do not import scroll traits here.
#[repr(C)]
#[derive(Copy, Clone, Eq, PartialEq, Default)]
#[cfg_attr(
feature = "alloc",
derive(scroll::Pread, scroll::Pwrite, scroll::SizeWith)
)]
/// Section Headers are typically used by humans and static linkers for additional information or how to relocate the object
///
/// **NOTE** section headers are strippable from a binary without any loss of portability/executability; _do not_ rely on them being there!
pub struct SectionHeader {
/// Section name (string tbl index)
pub sh_name: u32,
/// Section type
pub sh_type: u32,
/// Section flags
pub sh_flags: $size,
/// Section virtual addr at execution
pub sh_addr: $size,
/// Section file offset
pub sh_offset: $size,
/// Section size in bytes
pub sh_size: $size,
/// Link to another section
pub sh_link: u32,
/// Additional section information
pub sh_info: u32,
/// Section alignment
pub sh_addralign: $size,
/// Entry size if section holds table
pub sh_entsize: $size,
}
use plain;
// Declare that this is a plain type.
unsafe impl plain::Plain for SectionHeader {}
impl ::core::fmt::Debug for SectionHeader {
fn fmt(&self, f: &mut ::core::fmt::Formatter) -> ::core::fmt::Result {
f.debug_struct("SectionHeader")
.field("sh_name", &self.sh_name)
.field("sh_type", &sht_to_str(self.sh_type))
.field("sh_flags", &format_args!("0x{:x}", self.sh_flags))
.field("sh_addr", &format_args!("0x{:x}", self.sh_addr))
.field("sh_offset", &format_args!("0x{:x}", self.sh_offset))
.field("sh_size", &format_args!("0x{:x}", self.sh_size))
.field("sh_link", &format_args!("0x{:x}", self.sh_link))
.field("sh_info", &format_args!("0x{:x}", self.sh_info))
.field("sh_addralign", &format_args!("0x{:x}", self.sh_addralign))
.field("sh_entsize", &format_args!("0x{:x}", self.sh_entsize))
.finish()
}
}
};
}
/// Undefined section.
pub const SHN_UNDEF: u32 = 0;
/// Start of reserved indices.
pub const SHN_LORESERVE: u32 = 0xff00;
/// Start of processor-specific.
pub const SHN_LOPROC: u32 = 0xff00;
/// Order section before all others (Solaris).
pub const SHN_BEFORE: u32 = 0xff00;
/// Order section after all others (Solaris).
pub const SHN_AFTER: u32 = 0xff01;
/// End of processor-specific.
pub const SHN_HIPROC: u32 = 0xff1f;
/// Start of OS-specific.
pub const SHN_LOOS: u32 = 0xff20;
/// End of OS-specific.
pub const SHN_HIOS: u32 = 0xff3f;
/// Associated symbol is absolute.
pub const SHN_ABS: u32 = 0xfff1;
/// Associated symbol is common.
pub const SHN_COMMON: u32 = 0xfff2;
/// Index is in extra table.
pub const SHN_XINDEX: u32 = 0xffff;
/// End of reserved indices.
pub const SHN_HIRESERVE: u32 = 0xffff;
// === Legal values for sh_type (section type). ===
/// Section header table entry unused.
pub const SHT_NULL: u32 = 0;
/// Program data.
pub const SHT_PROGBITS: u32 = 1;
/// Symbol table.
pub const SHT_SYMTAB: u32 = 2;
/// String table.
pub const SHT_STRTAB: u32 = 3;
/// Relocation entries with addends.
pub const SHT_RELA: u32 = 4;
/// Symbol hash table.
pub const SHT_HASH: u32 = 5;
/// Dynamic linking information.
pub const SHT_DYNAMIC: u32 = 6;
/// Notes.
pub const SHT_NOTE: u32 = 7;
/// Program space with no data (bss).
pub const SHT_NOBITS: u32 = 8;
/// Relocation entries, no addends.
pub const SHT_REL: u32 = 9;
/// Reserved.
pub const SHT_SHLIB: u32 = 10;
/// Dynamic linker symbol table.
pub const SHT_DYNSYM: u32 = 11;
/// Array of constructors.
pub const SHT_INIT_ARRAY: u32 = 14;
/// Array of destructors.
pub const SHT_FINI_ARRAY: u32 = 15;
/// Array of pre-constructors.
pub const SHT_PREINIT_ARRAY: u32 = 16;
/// Section group.
pub const SHT_GROUP: u32 = 17;
/// Extended section indeces.
pub const SHT_SYMTAB_SHNDX: u32 = 18;
/// Number of defined types.
pub const SHT_NUM: u32 = 19;
/// Start OS-specific.
pub const SHT_LOOS: u32 = 0x6000_0000;
/// Object attributes.
pub const SHT_GNU_ATTRIBUTES: u32 = 0x6fff_fff5;
/// GNU-style hash table.
pub const SHT_GNU_HASH: u32 = 0x6fff_fff6;
/// Prelink library list.
pub const SHT_GNU_LIBLIST: u32 = 0x6fff_fff7;
/// Checksum for DSO content.
pub const SHT_CHECKSUM: u32 = 0x6fff_fff8;
/// Sun-specific low bound.
pub const SHT_LOSUNW: u32 = 0x6fff_fffa;
pub const SHT_SUNW_MOVE: u32 = 0x6fff_fffa;
pub const SHT_SUNW_COMDAT: u32 = 0x6fff_fffb;
pub const SHT_SUNW_SYMINFO: u32 = 0x6fff_fffc;
/// Version definition section.
pub const SHT_GNU_VERDEF: u32 = 0x6fff_fffd;
/// Version needs section.
pub const SHT_GNU_VERNEED: u32 = 0x6fff_fffe;
/// Version symbol table.
pub const SHT_GNU_VERSYM: u32 = 0x6fff_ffff;
/// Sun-specific high bound.
pub const SHT_HISUNW: u32 = 0x6fff_ffff;
/// End OS-specific type.
pub const SHT_HIOS: u32 = 0x6fff_ffff;
/// Start of processor-specific.
pub const SHT_LOPROC: u32 = 0x7000_0000;
/// X86-64 unwind information.
pub const SHT_X86_64_UNWIND: u32 = 0x7000_0001;
/// End of processor-specific.
pub const SHT_HIPROC: u32 = 0x7fff_ffff;
/// Start of application-specific.
pub const SHT_LOUSER: u32 = 0x8000_0000;
/// End of application-specific.
pub const SHT_HIUSER: u32 = 0x8fff_ffff;
// Legal values for sh_flags (section flags)
/// Writable.
pub const SHF_WRITE: u32 = 0x1;
/// Occupies memory during execution.
pub const SHF_ALLOC: u32 = 0x2;
/// Executable.
pub const SHF_EXECINSTR: u32 = 0x4;
/// Might be merged.
pub const SHF_MERGE: u32 = 0x10;
/// Contains nul-terminated strings.
pub const SHF_STRINGS: u32 = 0x20;
/// `sh_info' contains SHT index.
pub const SHF_INFO_LINK: u32 = 0x40;
/// Preserve order after combining.
pub const SHF_LINK_ORDER: u32 = 0x80;
/// Non-standard OS specific handling required.
pub const SHF_OS_NONCONFORMING: u32 = 0x100;
/// Section is member of a group.
pub const SHF_GROUP: u32 = 0x200;
/// Section hold thread-local data.
pub const SHF_TLS: u32 = 0x400;
/// Section with compressed data.
pub const SHF_COMPRESSED: u32 = 0x800;
/// OS-specific..
pub const SHF_MASKOS: u32 = 0x0ff0_0000;
/// Processor-specific.
pub const SHF_MASKPROC: u32 = 0xf000_0000;
/// Special ordering requirement (Solaris).
pub const SHF_ORDERED: u32 = 1 << 30;
/// Number of "regular" section header flags
pub const SHF_NUM_REGULAR_FLAGS: usize = 12;
/// Section is excluded unless referenced or allocated (Solaris).
pub const SHF_EXCLUDE: u32 = 0x80000000; // 1U << 31
pub const SHF_FLAGS: [u32; SHF_NUM_REGULAR_FLAGS] = [
SHF_WRITE,
SHF_ALLOC,
SHF_EXECINSTR,
SHF_MERGE,
SHF_STRINGS,
SHF_INFO_LINK,
SHF_LINK_ORDER,
SHF_OS_NONCONFORMING,
SHF_GROUP,
SHF_TLS,
SHF_COMPRESSED,
SHF_ORDERED,
];
pub fn sht_to_str(sht: u32) -> &'static str {
match sht {
SHT_NULL => "SHT_NULL",
SHT_PROGBITS => "SHT_PROGBITS",
SHT_SYMTAB => "SHT_SYMTAB",
SHT_STRTAB => "SHT_STRTAB",
SHT_RELA => "SHT_RELA",
SHT_HASH => "SHT_HASH",
SHT_DYNAMIC => "SHT_DYNAMIC",
SHT_NOTE => "SHT_NOTE",
SHT_NOBITS => "SHT_NOBITS",
SHT_REL => "SHT_REL",
SHT_SHLIB => "SHT_SHLIB",
SHT_DYNSYM => "SHT_DYNSYM",
SHT_INIT_ARRAY => "SHT_INIT_ARRAY",
SHT_FINI_ARRAY => "SHT_FINI_ARRAY",
SHT_PREINIT_ARRAY => "SHT_PREINIT_ARRAY",
SHT_GROUP => "SHT_GROUP",
SHT_SYMTAB_SHNDX => "SHT_SYMTAB_SHNDX",
SHT_NUM => "SHT_NUM",
SHT_LOOS => "SHT_LOOS",
SHT_GNU_ATTRIBUTES => "SHT_GNU_ATTRIBUTES",
SHT_GNU_HASH => "SHT_GNU_HASH",
SHT_GNU_LIBLIST => "SHT_GNU_LIBLIST",
SHT_CHECKSUM => "SHT_CHECKSUM",
SHT_SUNW_MOVE => "SHT_SUNW_MOVE",
SHT_SUNW_COMDAT => "SHT_SUNW_COMDAT",
SHT_SUNW_SYMINFO => "SHT_SUNW_SYMINFO",
SHT_GNU_VERDEF => "SHT_GNU_VERDEF",
SHT_GNU_VERNEED => "SHT_GNU_VERNEED",
SHT_GNU_VERSYM => "SHT_GNU_VERSYM",
SHT_LOPROC => "SHT_LOPROC",
SHT_X86_64_UNWIND => "SHT_X86_64_UNWIND",
SHT_HIPROC => "SHT_HIPROC",
SHT_LOUSER => "SHT_LOUSER",
SHT_HIUSER => "SHT_HIUSER",
_ => "UNKNOWN_SHT",
}
}
pub fn shf_to_str(shf: u32) -> &'static str {
match shf {
SHF_WRITE => "SHF_WRITE",
SHF_ALLOC => "SHF_ALLOC",
SHF_EXECINSTR => "SHF_EXECINSTR",
SHF_MERGE => "SHF_MERGE",
SHF_STRINGS => "SHF_STRINGS",
SHF_INFO_LINK => "SHF_INFO_LINK",
SHF_LINK_ORDER => "SHF_LINK_ORDER",
SHF_OS_NONCONFORMING => "SHF_OS_NONCONFORMING",
SHF_GROUP => "SHF_GROUP",
SHF_TLS => "SHF_TLS",
SHF_COMPRESSED => "SHF_COMPRESSED",
//SHF_MASKOS..SHF_MASKPROC => "SHF_OSFLAG",
SHF_ORDERED => "SHF_ORDERED",
_ => "SHF_UNKNOWN",
}
}
macro_rules! elf_section_header_std_impl { ($size:ty) => {
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn size_of() {
assert_eq!(::std::mem::size_of::<SectionHeader>(), SIZEOF_SHDR);
}
}
if_alloc! {
use crate::elf::section_header::SectionHeader as ElfSectionHeader;
use plain::Plain;
use alloc::vec::Vec;
if_std! {
use crate::error::Result;
use std::fs::File;
use std::io::{Read, Seek};
use std::io::SeekFrom::Start;
}
impl From<SectionHeader> for ElfSectionHeader {
fn from(sh: SectionHeader) -> Self {
ElfSectionHeader {
sh_name: sh.sh_name as usize,
sh_type: sh.sh_type,
sh_flags: u64::from(sh.sh_flags),
sh_addr: u64::from(sh.sh_addr),
sh_offset: u64::from(sh.sh_offset),
sh_size: u64::from(sh.sh_size),
sh_link: sh.sh_link,
sh_info: sh.sh_info,
sh_addralign: u64::from(sh.sh_addralign),
sh_entsize: u64::from(sh.sh_entsize),
}
}
}
impl From<ElfSectionHeader> for SectionHeader {
fn from(sh: ElfSectionHeader) -> Self {
SectionHeader {
sh_name : sh.sh_name as u32,
sh_type : sh.sh_type,
sh_flags : sh.sh_flags as $size,
sh_addr : sh.sh_addr as $size,
sh_offset : sh.sh_offset as $size,
sh_size : sh.sh_size as $size,
sh_link : sh.sh_link,
sh_info : sh.sh_info,
sh_addralign: sh.sh_addralign as $size,
sh_entsize : sh.sh_entsize as $size,
}
}
}
impl SectionHeader {
// FIXME: > 65535 sections
pub fn from_bytes(bytes: &[u8], shnum: usize) -> Vec<SectionHeader> {
let mut shdrs = vec![SectionHeader::default(); shnum];
shdrs.copy_from_bytes(bytes).expect("buffer is too short for given number of entries");
shdrs
}
#[cfg(feature = "std")]
// FIXME: > 65535 sections
pub fn from_fd(fd: &mut File, offset: u64, shnum: usize) -> Result<Vec<SectionHeader>> {
let mut shdrs = vec![SectionHeader::default(); shnum];
fd.seek(Start(offset))?;
unsafe {
fd.read_exact(plain::as_mut_bytes(&mut *shdrs))?;
}
Ok(shdrs)
}
}
} // end if_alloc
};}
pub mod section_header32 {
pub use crate::elf::section_header::*;
elf_section_header!(u32);
pub const SIZEOF_SHDR: usize = 40;
elf_section_header_std_impl!(u32);
}
pub mod section_header64 {
pub use crate::elf::section_header::*;
elf_section_header!(u64);
pub const SIZEOF_SHDR: usize = 64;
elf_section_header_std_impl!(u64);
}
///////////////////////////////
// Std/analysis/Unified Structs
///////////////////////////////
if_alloc! {
use crate::error;
use core::fmt;
use core::result;
use core::ops::Range;
use scroll::ctx;
use crate::container::{Container, Ctx};
#[cfg(feature = "endian_fd")]
use alloc::vec::Vec;
#[derive(Default, PartialEq, Clone)]
/// A unified SectionHeader - convertable to and from 32-bit and 64-bit variants
pub struct SectionHeader {
/// Section name (string tbl index)
pub sh_name: usize,
/// Section type
pub sh_type: u32,
/// Section flags
pub sh_flags: u64,
/// Section virtual addr at execution
pub sh_addr: u64,
/// Section file offset
pub sh_offset: u64,
/// Section size in bytes
pub sh_size: u64,
/// Link to another section
pub sh_link: u32,
/// Additional section information
pub sh_info: u32,
/// Section alignment
pub sh_addralign: u64,
/// Entry size if section holds table
pub sh_entsize: u64,
}
impl SectionHeader {
/// Return the size of the underlying section header, given a `Ctx`
#[inline]
pub fn size(ctx: Ctx) -> usize {
use scroll::ctx::SizeWith;
Self::size_with(&ctx)
}
pub fn new() -> Self {
SectionHeader {
sh_name: 0,
sh_type: SHT_PROGBITS,
sh_flags: u64::from(SHF_ALLOC),
sh_addr: 0,
sh_offset: 0,
sh_size: 0,
sh_link: 0,
sh_info: 0,
sh_addralign: 2 << 8,
sh_entsize: 0,
}
}
/// Returns this section header's file offset range,
/// if the section occupies space in fhe file.
pub fn file_range(&self) -> Option<Range<usize>> {
// Sections with type SHT_NOBITS have no data in the file itself,
// they only exist in memory.
if self.sh_type == SHT_NOBITS {
None
} else {
Some(self.sh_offset as usize..(self.sh_offset as usize).saturating_add(self.sh_size as usize))
}
}
/// Returns this section header's virtual memory range
pub fn vm_range(&self) -> Range<usize> {
self.sh_addr as usize..(self.sh_addr as usize).saturating_add(self.sh_size as usize)
}
/// Parse `count` section headers from `bytes` at `offset`, using the given `ctx`
/// Assuming this is read from the whole file, it will check offset.
#[cfg(feature = "endian_fd")]
pub fn parse(bytes: &[u8], offset: usize, count: usize, ctx: Ctx) -> error::Result<Vec<SectionHeader>> {
// Zero offset means no section headers, not even the null section header.
if offset == 0 {
return Ok(Vec::new());
}
Self::parse_from(bytes, offset, count, ctx)
}
/// Parse `count` section headers from `bytes` at `offset`, using the given `ctx`
/// without performing any offset checking to allow parsing relatively
#[cfg(feature = "endian_fd")]
pub fn parse_from(bytes: &[u8], mut offset: usize, mut count: usize, ctx: Ctx) -> error::Result<Vec<SectionHeader>> {
use scroll::Pread;
let empty_sh = bytes.gread_with::<SectionHeader>(&mut offset, ctx)?;
if count == 0 as usize {
// Zero count means either no section headers or the number of section headers
// overflows SHN_LORESERVE, in which case the count is stored in the sh_size field
// of the null section header.
count = empty_sh.sh_size as usize;
}
// Sanity check to avoid OOM
if count > bytes.len() / Self::size(ctx) {
return Err(error::Error::BufferTooShort(count, "section headers"));
}
let mut section_headers = Vec::with_capacity(count);
section_headers.push(empty_sh);
for _ in 1..count {
let shdr = bytes.gread_with(&mut offset, ctx)?;
section_headers.push(shdr);
}
Ok(section_headers)
}
pub fn check_size(&self, size: usize) -> error::Result<()> {
if self.sh_type == SHT_NOBITS || self.sh_size == 0 {
return Ok(());
}
let (end, overflow) = self.sh_offset.overflowing_add(self.sh_size);
if overflow || end > size as u64 {
let message = format!("Section {} size ({}) + offset ({}) is out of bounds. Overflowed: {}",
self.sh_name, self.sh_offset, self.sh_size, overflow);
return Err(error::Error::Malformed(message));
}
let (_, overflow) = self.sh_addr.overflowing_add(self.sh_size);
if overflow {
let message = format!("Section {} size ({}) + addr ({}) is out of bounds. Overflowed: {}",
self.sh_name, self.sh_addr, self.sh_size, overflow);
return Err(error::Error::Malformed(message));
}
Ok(())
}
pub fn is_relocation(&self) -> bool {
self.sh_type == SHT_RELA
}
pub fn is_executable(&self) -> bool {
self.is_alloc() && self.sh_flags as u32 & SHF_EXECINSTR == SHF_EXECINSTR
}
pub fn is_writable(&self) -> bool {
self.is_alloc() && self.sh_flags as u32 & SHF_WRITE == SHF_WRITE
}
pub fn is_alloc(&self) -> bool {
self.sh_flags as u32 & SHF_ALLOC == SHF_ALLOC
}
}
impl fmt::Debug for SectionHeader {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("SectionHeader")
.field("sh_name", &self.sh_name)
.field("sh_type", &sht_to_str(self.sh_type))
.field("sh_flags", &format_args!("0x{:x}", self.sh_flags))
.field("sh_addr", &format_args!("0x{:x}", self.sh_addr))
.field("sh_offset", &format_args!("0x{:x}", self.sh_offset))
.field("sh_size", &format_args!("0x{:x}", self.sh_size))
.field("sh_link", &format_args!("0x{:x}", self.sh_link))
.field("sh_info", &format_args!("0x{:x}", self.sh_info))
.field("sh_addralign", &format_args!("0x{:x}", self.sh_addralign))
.field("sh_entsize", &format_args!("0x{:x}", self.sh_entsize))
.finish()
}
}
impl ctx::SizeWith<Ctx> for SectionHeader {
fn size_with( &Ctx { container, .. }: &Ctx) -> usize {
match container {
Container::Little => {
section_header32::SIZEOF_SHDR
},
Container::Big => {
section_header64::SIZEOF_SHDR
},
}
}
}
impl<'a> ctx::TryFromCtx<'a, Ctx> for SectionHeader {
type Error = crate::error::Error;
fn try_from_ctx(bytes: &'a [u8], Ctx {container, le}: Ctx) -> result::Result<(Self, usize), Self::Error> {
use scroll::Pread;
let res = match container {
Container::Little => {
(bytes.pread_with::<section_header32::SectionHeader>(0, le)?.into(), section_header32::SIZEOF_SHDR)
},
Container::Big => {
(bytes.pread_with::<section_header64::SectionHeader>(0, le)?.into(), section_header64::SIZEOF_SHDR)
}
};
Ok(res)
}
}
impl ctx::TryIntoCtx<Ctx> for SectionHeader {
type Error = crate::error::Error;
fn try_into_ctx(self, bytes: &mut [u8], Ctx {container, le}: Ctx) -> result::Result<usize, Self::Error> {
use scroll::Pwrite;
match container {
Container::Little => {
let shdr: section_header32::SectionHeader = self.into();
Ok(bytes.pwrite_with(shdr, 0, le)?)
},
Container::Big => {
let shdr: section_header64::SectionHeader = self.into();
Ok(bytes.pwrite_with(shdr, 0, le)?)
}
}
}
}
impl ctx::IntoCtx<Ctx> for SectionHeader {
fn into_ctx(self, bytes: &mut [u8], Ctx {container, le}: Ctx) {
use scroll::Pwrite;
match container {
Container::Little => {
let shdr: section_header32::SectionHeader = self.into();
bytes.pwrite_with(shdr, 0, le).unwrap();
},
Container::Big => {
let shdr: section_header64::SectionHeader = self.into();
bytes.pwrite_with(shdr, 0, le).unwrap();
}
}
}
}
} // end if_alloc