mozilla-central/third_party/rust/goblin/src/elf/symver.rs (file symbol)

Source code

Revision control

Copy as Markdown

Other Tools

//! Symbol versioning
//!
//! Implementation of the GNU symbol versioning extension according to
//! [LSB Core Specification - Symbol Versioning][lsb-symver].
//!
//! # Examples
//!
//! List the dependencies of an ELF file that have [version needed][lsb-verneed] information along
//! with the versions needed for each dependency.
//! ```rust
//! use goblin::error::Error;
//!
//! pub fn show_verneed(bytes: &[u8]) -> Result<(), Error> {
//! let binary = goblin::elf::Elf::parse(&bytes)?;
//!
//! if let Some(verneed) = binary.verneed {
//! for need_file in verneed.iter() {
//! println!(
//! "Depend on {:?} with version(s):",
//! binary.dynstrtab.get_at(need_file.vn_file)
//! );
//! for need_ver in need_file.iter() {
//! println!("{:?}", binary.dynstrtab.get_at(need_ver.vna_name));
//! }
//! }
//! }
//!
//! Ok(())
//! }
//! ```
//!
//! List the [version defined][lsb-verdef] information of an ELF file, effectively listing the version
//! defined by this ELF file.
//! ```rust
//! use goblin::error::Error;
//!
//! pub fn show_verdef(bytes: &[u8]) -> Result<(), Error> {
//! let binary = goblin::elf::Elf::parse(&bytes)?;
//!
//! if let Some(verdef) = &binary.verdef {
//! for def in verdef.iter() {
//! for (n, aux) in def.iter().enumerate() {
//! let name = binary.dynstrtab.get_at(aux.vda_name);
//! match n {
//! 0 => print!("Name: {:?}", name),
//! 1 => print!(" Parent: {:?}", name),
//! _ => print!(", {:?}", name),
//! }
//! }
//! print!("\n");
//! }
//! }
//!
//! Ok(())
//! }
//! ```
//!
use crate::container;
use crate::elf::section_header::{SectionHeader, SHT_GNU_VERDEF, SHT_GNU_VERNEED, SHT_GNU_VERSYM};
use crate::error::Result;
use core::iter::FusedIterator;
use scroll::Pread;
/******************
* ELF Constants *
******************/
// Versym constants.
/// Constant describing a local symbol, see [`Versym::is_local`].
pub const VER_NDX_LOCAL: u16 = 0;
/// Constant describing a global symbol, see [`Versym::is_global`].
pub const VER_NDX_GLOBAL: u16 = 1;
/// Bitmask to check hidden bit, see [`Versym::is_hidden`].
pub const VERSYM_HIDDEN: u16 = 0x8000;
/// Bitmask to get version information, see [`Versym::version`].
pub const VERSYM_VERSION: u16 = 0x7fff;
// Verdef constants.
/// Bitmask to check `base` flag in [`Verdef::vd_flags`].
pub const VER_FLG_BASE: u16 = 0x1;
/// Bitmask to check `weak` flag in [`Verdef::vd_flags`].
pub const VER_FLG_WEAK: u16 = 0x2;
/// Bitmask to check `info` flag in [`Verdef::vd_flags`].
pub const VER_FLG_INFO: u16 = 0x4;
/********************
* ELF Structures *
********************/
/// An ELF `Symbol Version` entry.
///
#[repr(C)]
#[derive(Debug, Pread)]
struct ElfVersym {
vs_val: u16,
}
/// An ELF `Version Definition` entry Elfxx_Verdef.
///
#[repr(C)]
#[derive(Debug, Pread)]
struct ElfVerdef {
vd_version: u16,
vd_flags: u16,
vd_ndx: u16,
vd_cnt: u16,
vd_hash: u32,
vd_aux: u32,
vd_next: u32,
}
/// An ELF `Version Definition Auxiliary` entry Elfxx_Verdaux.
///
#[repr(C)]
#[derive(Debug, Pread)]
struct ElfVerdaux {
vda_name: u32,
vda_next: u32,
}
/// An ELF `Version Need` entry Elfxx_Verneed.
///
#[repr(C)]
#[derive(Debug, Pread)]
struct ElfVerneed {
vn_version: u16,
vn_cnt: u16,
vn_file: u32,
vn_aux: u32,
vn_next: u32,
}
/// An ELF `Version Need Auxiliary` entry Elfxx_Vernaux.
///
#[repr(C)]
#[derive(Debug, Pread)]
struct ElfVernaux {
vna_hash: u32,
vna_flags: u16,
vna_other: u16,
vna_name: u32,
vna_next: u32,
}
/********************
* Symbol Version *
********************/
/// Helper struct to iterate over [Symbol Version][Versym] entries.
#[derive(Debug)]
pub struct VersymSection<'a> {
bytes: &'a [u8],
ctx: container::Ctx,
}
impl<'a> VersymSection<'a> {
pub fn parse(
bytes: &'a [u8],
shdrs: &[SectionHeader],
ctx: container::Ctx,
) -> Result<Option<VersymSection<'a>>> {
// Get fields needed from optional `symbol version` section.
let (offset, size) =
if let Some(shdr) = shdrs.iter().find(|shdr| shdr.sh_type == SHT_GNU_VERSYM) {
(shdr.sh_offset as usize, shdr.sh_size as usize)
} else {
return Ok(None);
};
// Get a slice of bytes of the `version definition` section content.
let bytes: &'a [u8] = bytes.pread_with(offset, size)?;
Ok(Some(VersymSection { bytes, ctx }))
}
/// Get an iterator over the [`Versym`] entries.
#[inline]
pub fn iter(&'a self) -> VersymIter<'a> {
self.into_iter()
}
/// True if there are no [`Versym`] entries.
#[inline]
pub fn is_empty(&self) -> bool {
self.bytes.is_empty()
}
/// Number of [`Versym`] entries.
#[inline]
pub fn len(&self) -> usize {
let entsize = core::mem::size_of::<ElfVersym>();
self.bytes.len() / entsize
}
/// Get [`Versym`] entry at index.
#[inline]
pub fn get_at(&self, idx: usize) -> Option<Versym> {
let entsize = core::mem::size_of::<ElfVersym>();
let offset = idx.checked_mul(entsize)?;
self.bytes
.pread_with::<ElfVersym>(offset, self.ctx.le)
.ok()
.map(Versym::from)
}
}
impl<'a> IntoIterator for &'_ VersymSection<'a> {
type Item = <VersymIter<'a> as Iterator>::Item;
type IntoIter = VersymIter<'a>;
fn into_iter(self) -> Self::IntoIter {
VersymIter {
bytes: self.bytes,
offset: 0,
ctx: self.ctx,
}
}
}
/// Iterator over the [`Versym`] entries from the [`SHT_GNU_VERSYM`] section.
pub struct VersymIter<'a> {
bytes: &'a [u8],
offset: usize,
ctx: container::Ctx,
}
impl<'a> Iterator for VersymIter<'a> {
type Item = Versym;
fn next(&mut self) -> Option<Self::Item> {
if self.offset >= self.bytes.len() {
None
} else {
self.bytes
.gread_with::<ElfVersym>(&mut self.offset, self.ctx.le)
.ok()
.map(Versym::from)
.or_else(|| {
// self.bytes are not a multiple of ElfVersym.
// Adjust offset to continue yielding Nones.
self.offset = self.bytes.len();
None
})
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let len = (self.bytes.len() - self.offset) / core::mem::size_of::<Self::Item>();
(len, Some(len))
}
}
impl ExactSizeIterator for VersymIter<'_> {}
impl FusedIterator for VersymIter<'_> {}
/// An ELF [Symbol Version][lsb-versym] entry.
///
#[derive(Debug)]
pub struct Versym {
pub vs_val: u16,
}
impl Versym {
/// Returns true if the symbol is local and not available outside the object according to
/// [`VER_NDX_LOCAL`].
#[inline]
pub fn is_local(&self) -> bool {
self.vs_val == VER_NDX_LOCAL
}
/// Returns true if the symbol is defined in this object and globally available according
/// to [`VER_NDX_GLOBAL`].
#[inline]
pub fn is_global(&self) -> bool {
self.vs_val == VER_NDX_GLOBAL
}
/// Returns true if the `hidden` bit is set according to the [`VERSYM_HIDDEN`] bitmask.
#[inline]
pub fn is_hidden(&self) -> bool {
(self.vs_val & VERSYM_HIDDEN) == VERSYM_HIDDEN
}
/// Returns the symbol version index according to the [`VERSYM_VERSION`] bitmask.
#[inline]
pub fn version(&self) -> u16 {
self.vs_val & VERSYM_VERSION
}
}
impl From<ElfVersym> for Versym {
fn from(ElfVersym { vs_val }: ElfVersym) -> Self {
Versym { vs_val }
}
}
/************************
* Version Definition *
************************/
/// Helper struct to iterate over [Version Definition][Verdef] and [Version Definition
/// Auxiliary][Verdaux] entries.
#[derive(Debug)]
pub struct VerdefSection<'a> {
/// String table used to resolve version strings.
bytes: &'a [u8],
count: usize,
ctx: container::Ctx,
}
impl<'a> VerdefSection<'a> {
pub fn parse(
bytes: &'a [u8],
shdrs: &[SectionHeader],
ctx: container::Ctx,
) -> Result<Option<VerdefSection<'a>>> {
// Get fields needed from optional `version definition` section.
let (offset, size, count) =
if let Some(shdr) = shdrs.iter().find(|shdr| shdr.sh_type == SHT_GNU_VERDEF) {
(
shdr.sh_offset as usize,
shdr.sh_size as usize,
shdr.sh_info as usize, // Encodes the number of ElfVerdef entries.
)
} else {
return Ok(None);
};
// Get a slice of bytes of the `version definition` section content.
let bytes: &'a [u8] = bytes.pread_with(offset, size)?;
Ok(Some(VerdefSection { bytes, count, ctx }))
}
/// Get an iterator over the [`Verdef`] entries.
#[inline]
pub fn iter(&'a self) -> VerdefIter<'a> {
self.into_iter()
}
}
impl<'a> IntoIterator for &'_ VerdefSection<'a> {
type Item = <VerdefIter<'a> as Iterator>::Item;
type IntoIter = VerdefIter<'a>;
#[inline]
fn into_iter(self) -> Self::IntoIter {
VerdefIter {
bytes: self.bytes,
count: self.count,
index: 0,
offset: 0,
ctx: self.ctx,
}
}
}
/// Iterator over the [`Verdef`] entries from the [`SHT_GNU_VERDEF`] section.
pub struct VerdefIter<'a> {
bytes: &'a [u8],
count: usize,
index: usize,
offset: usize,
ctx: container::Ctx,
}
impl<'a> Iterator for VerdefIter<'a> {
type Item = Verdef<'a>;
fn next(&mut self) -> Option<Self::Item> {
if self.index >= self.count {
None
} else {
self.index += 1;
let do_next = |iter: &mut Self| {
let ElfVerdef {
vd_version,
vd_flags,
vd_ndx,
vd_cnt,
vd_hash,
vd_aux,
vd_next,
} = iter.bytes.pread_with(iter.offset, iter.ctx.le).ok()?;
// Validate offset to first ElfVerdaux entry.
let offset = iter.offset.checked_add(vd_aux as usize)?;
// Validate if offset is valid index into bytes slice.
if offset >= iter.bytes.len() {
return None;
}
// Get a slice of bytes starting with the first ElfVerdaux entry.
let bytes: &'a [u8] = &iter.bytes[offset..];
// Bump the offset to the next ElfVerdef entry.
iter.offset = iter.offset.checked_add(vd_next as usize)?;
// Start yielding None on the next call if there is no next offset.
if vd_next == 0 {
iter.index = iter.count;
}
Some(Verdef {
vd_version,
vd_flags,
vd_ndx,
vd_cnt,
vd_hash,
vd_aux,
vd_next,
bytes,
ctx: iter.ctx,
})
};
do_next(self).or_else(|| {
// Adjust current index to count in case of an error.
self.index = self.count;
None
})
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let len = self.count - self.index;
(0, Some(len))
}
}
impl ExactSizeIterator for VerdefIter<'_> {}
impl FusedIterator for VerdefIter<'_> {}
/// An ELF [Version Definition][lsb-verdef] entry .
///
#[derive(Debug)]
pub struct Verdef<'a> {
/// Version revision. This field shall be set to 1.
pub vd_version: u16,
/// Version information flag bitmask.
pub vd_flags: u16,
/// Version index numeric value referencing the SHT_GNU_versym section.
pub vd_ndx: u16,
/// Number of associated verdaux array entries.
pub vd_cnt: u16,
/// Version name hash value (ELF hash function).
pub vd_hash: u32,
/// Offset in bytes to a corresponding entry in an array of Elfxx_Verdaux structures.
pub vd_aux: u32,
/// Offset to the next verdef entry, in bytes.
pub vd_next: u32,
bytes: &'a [u8],
ctx: container::Ctx,
}
impl<'a> Verdef<'a> {
/// Get an iterator over the [`Verdaux`] entries of this [`Verdef`] entry.
#[inline]
pub fn iter(&'a self) -> VerdauxIter<'a> {
self.into_iter()
}
}
impl<'a> IntoIterator for &'_ Verdef<'a> {
type Item = <VerdauxIter<'a> as Iterator>::Item;
type IntoIter = VerdauxIter<'a>;
fn into_iter(self) -> Self::IntoIter {
VerdauxIter {
bytes: self.bytes,
count: self.vd_cnt,
index: 0,
offset: 0,
ctx: self.ctx,
}
}
}
/// Iterator over the [`Verdaux`] entries for an specific [`Verdef`] entry.
pub struct VerdauxIter<'a> {
bytes: &'a [u8],
count: u16,
index: u16,
offset: usize,
ctx: container::Ctx,
}
impl<'a> Iterator for VerdauxIter<'a> {
type Item = Verdaux;
fn next(&mut self) -> Option<Self::Item> {
if self.index >= self.count {
None
} else {
self.index += 1;
let do_next = |iter: &mut Self| {
let ElfVerdaux { vda_name, vda_next } =
iter.bytes.pread_with(iter.offset, iter.ctx.le).ok()?;
// Bump the offset to the next ElfVerdaux entry.
iter.offset = iter.offset.checked_add(vda_next as usize)?;
// Start yielding None on the next call if there is no next offset.
if vda_next == 0 {
iter.index = iter.count;
}
Some(Verdaux {
vda_name: vda_name as usize,
vda_next,
})
};
do_next(self).or_else(|| {
// Adjust current index to count in case of an error.
self.index = self.count;
None
})
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let len = usize::from(self.count - self.index);
(0, Some(len))
}
}
impl ExactSizeIterator for VerdauxIter<'_> {}
impl FusedIterator for VerdauxIter<'_> {}
/// An ELF [Version Definition Auxiliary][lsb-verdaux] entry.
///
#[derive(Debug)]
pub struct Verdaux {
/// Offset to the version or dependency name string in the section header, in bytes.
pub vda_name: usize,
/// Offset to the next verdaux entry, in bytes.
pub vda_next: u32,
}
/**************************
* Version Requirements *
**************************/
/// Helper struct to iterate over [Version Needed][Verneed] and [Version Needed
/// Auxiliary][Vernaux] entries.
#[derive(Debug)]
pub struct VerneedSection<'a> {
bytes: &'a [u8],
count: usize,
ctx: container::Ctx,
}
impl<'a> VerneedSection<'a> {
/// Try to parse the optional [`SHT_GNU_VERNEED`] section.
pub fn parse(
bytes: &'a [u8],
shdrs: &[SectionHeader],
ctx: container::Ctx,
) -> Result<Option<VerneedSection<'a>>> {
// Get fields needed from optional `version needed` section.
let (offset, size, count) =
if let Some(shdr) = shdrs.iter().find(|shdr| shdr.sh_type == SHT_GNU_VERNEED) {
(
shdr.sh_offset as usize,
shdr.sh_size as usize,
shdr.sh_info as usize, // Encodes the number of ElfVerneed entries.
)
} else {
return Ok(None);
};
// Get a slice of bytes of the `version needed` section content.
let bytes: &'a [u8] = bytes.pread_with(offset, size)?;
Ok(Some(VerneedSection { bytes, count, ctx }))
}
/// Get an iterator over the [`Verneed`] entries.
#[inline]
pub fn iter(&'a self) -> VerneedIter<'a> {
self.into_iter()
}
}
impl<'a> IntoIterator for &'_ VerneedSection<'a> {
type Item = <VerneedIter<'a> as Iterator>::Item;
type IntoIter = VerneedIter<'a>;
#[inline]
fn into_iter(self) -> Self::IntoIter {
VerneedIter {
bytes: self.bytes,
count: self.count,
index: 0,
offset: 0,
ctx: self.ctx,
}
}
}
/// Iterator over the [`Verneed`] entries from the [`SHT_GNU_VERNEED`] section.
pub struct VerneedIter<'a> {
bytes: &'a [u8],
count: usize,
index: usize,
offset: usize,
ctx: container::Ctx,
}
impl<'a> Iterator for VerneedIter<'a> {
type Item = Verneed<'a>;
fn next(&mut self) -> Option<Self::Item> {
if self.index >= self.count {
None
} else {
self.index += 1;
let do_next = |iter: &mut Self| {
let ElfVerneed {
vn_version,
vn_cnt,
vn_file,
vn_aux,
vn_next,
} = iter.bytes.pread_with(iter.offset, iter.ctx.le).ok()?;
// Validate offset to first ElfVernaux entry.
let offset = iter.offset.checked_add(vn_aux as usize)?;
// Validate if offset is valid index into bytes slice.
if offset >= iter.bytes.len() {
return None;
}
// Get a slice of bytes starting with the first ElfVernaux entry.
let bytes: &'a [u8] = &iter.bytes[offset..];
// Bump the offset to the next ElfVerneed entry.
iter.offset = iter.offset.checked_add(vn_next as usize)?;
// Start yielding None on the next call if there is no next offset.
if vn_next == 0 {
iter.index = iter.count;
}
Some(Verneed {
vn_version,
vn_cnt,
vn_file: vn_file as usize,
vn_aux,
vn_next,
bytes,
ctx: iter.ctx,
})
};
do_next(self).or_else(|| {
// Adjust current index to count in case of an error.
self.index = self.count;
None
})
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let len = self.count - self.index;
(0, Some(len))
}
}
impl ExactSizeIterator for VerneedIter<'_> {}
impl FusedIterator for VerneedIter<'_> {}
/// An ELF [Version Need][lsb-verneed] entry .
///
#[derive(Debug)]
pub struct Verneed<'a> {
/// Version of structure. This value is currently set to 1, and will be reset if the versioning
/// implementation is incompatibly altered.
pub vn_version: u16,
/// Number of associated verneed array entries.
pub vn_cnt: u16,
/// Offset to the file name string in the section header, in bytes.
pub vn_file: usize,
/// Offset to a corresponding entry in the vernaux array, in bytes.
pub vn_aux: u32,
/// Offset to the next verneed entry, in bytes.
pub vn_next: u32,
bytes: &'a [u8],
ctx: container::Ctx,
}
impl<'a> Verneed<'a> {
/// Get an iterator over the [`Vernaux`] entries of this [`Verneed`] entry.
#[inline]
pub fn iter(&'a self) -> VernauxIter<'a> {
self.into_iter()
}
}
impl<'a> IntoIterator for &'_ Verneed<'a> {
type Item = <VernauxIter<'a> as Iterator>::Item;
type IntoIter = VernauxIter<'a>;
#[inline]
fn into_iter(self) -> Self::IntoIter {
VernauxIter {
bytes: self.bytes,
count: self.vn_cnt,
index: 0,
offset: 0,
ctx: self.ctx,
}
}
}
/// Iterator over the [`Vernaux`] entries for an specific [`Verneed`] entry.
pub struct VernauxIter<'a> {
bytes: &'a [u8],
count: u16,
index: u16,
offset: usize,
ctx: container::Ctx,
}
impl<'a> Iterator for VernauxIter<'a> {
type Item = Vernaux;
fn next(&mut self) -> Option<Self::Item> {
if self.index >= self.count {
None
} else {
self.index += 1;
let do_next = |iter: &mut Self| {
let ElfVernaux {
vna_hash,
vna_flags,
vna_other,
vna_name,
vna_next,
} = iter.bytes.pread_with(iter.offset, iter.ctx.le).ok()?;
// Bump the offset to the next ElfVernaux entry.
iter.offset = iter.offset.checked_add(vna_next as usize)?;
// Start yielding None on the next call if there is no next offset.
if vna_next == 0 {
iter.index = iter.count;
}
Some(Vernaux {
vna_hash,
vna_flags,
vna_other,
vna_name: vna_name as usize,
vna_next,
})
};
do_next(self).or_else(|| {
// Adjust current index to count in case of an error.
self.index = self.count;
None
})
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let len = usize::from(self.count - self.index);
(0, Some(len))
}
}
impl ExactSizeIterator for VernauxIter<'_> {}
impl FusedIterator for VernauxIter<'_> {}
/// An ELF [Version Need Auxiliary][lsb-vernaux] entry.
///
#[derive(Debug)]
pub struct Vernaux {
/// Dependency name hash value (ELF hash function).
pub vna_hash: u32,
/// Dependency information flag bitmask.
pub vna_flags: u16,
/// Object file version identifier used in the .gnu.version symbol version array. Bit number 15
/// controls whether or not the object is hidden; if this bit is set, the object cannot be used
/// and the static linker will ignore the symbol's presence in the object.
pub vna_other: u16,
/// Offset to the dependency name string in the section header, in bytes.
pub vna_name: usize,
/// Offset to the next vernaux entry, in bytes.
pub vna_next: u32,
}
#[cfg(test)]
mod test {
use super::{ElfVerdaux, ElfVerdef, ElfVernaux, ElfVerneed, ElfVersym};
use super::{Versym, VERSYM_HIDDEN, VER_NDX_GLOBAL, VER_NDX_LOCAL};
use core::mem::size_of;
#[test]
fn check_size() {
assert_eq!(2, size_of::<ElfVersym>());
assert_eq!(20, size_of::<ElfVerdef>());
assert_eq!(8, size_of::<ElfVerdaux>());
assert_eq!(16, size_of::<ElfVerneed>());
assert_eq!(16, size_of::<ElfVernaux>());
}
#[test]
fn check_versym() {
let local = Versym {
vs_val: VER_NDX_LOCAL,
};
assert_eq!(true, local.is_local());
assert_eq!(false, local.is_global());
assert_eq!(false, local.is_hidden());
assert_eq!(VER_NDX_LOCAL, local.version());
let global = Versym {
vs_val: VER_NDX_GLOBAL,
};
assert_eq!(false, global.is_local());
assert_eq!(true, global.is_global());
assert_eq!(false, global.is_hidden());
assert_eq!(VER_NDX_GLOBAL, global.version());
let hidden = Versym {
vs_val: VERSYM_HIDDEN,
};
assert_eq!(false, hidden.is_local());
assert_eq!(false, hidden.is_global());
assert_eq!(true, hidden.is_hidden());
assert_eq!(0, hidden.version());
let hidden = Versym {
vs_val: VERSYM_HIDDEN | 0x123,
};
assert_eq!(false, hidden.is_local());
assert_eq!(false, hidden.is_global());
assert_eq!(true, hidden.is_hidden());
assert_eq!(0x123, hidden.version());
}
}