Files
RedBear-OS/src/ld_so/linker.rs
T
oddcoder de03566158 Enable RTLD debugging protocol system-wide
This patch makes use of the data structures and functions impelemented
in the last patch to enable RTLD debugging protocol as per SVR4
2020-04-13 12:39:51 +02:00

720 lines
26 KiB
Rust

use alloc::{
boxed::Box,
collections::BTreeMap,
string::{String, ToString},
vec::Vec,
};
use core::{
mem::{size_of, transmute},
ptr, slice,
};
use goblin::{
elf::{
program_header,
r#dyn::{Dyn, DT_DEBUG},
reloc, sym, Elf,
},
error::{Error, Result},
};
use crate::{
c_str::CString,
fs::File,
header::{fcntl, sys_mman, unistd},
io::Read,
platform::types::c_void,
};
use super::{
debug::{RTLDDebug, RTLDState, _dl_debug_state, _r_debug},
tcb::{Master, Tcb},
PAGE_SIZE,
};
#[cfg(target_os = "redox")]
const PATH_SEP: char = ';';
#[cfg(target_os = "linux")]
const PATH_SEP: char = ':';
pub struct DSO {
pub name: String,
pub base_addr: usize,
pub entry_point: usize,
}
pub struct Linker {
// Used by load
/// Library path to search when loading library by name
library_path: String,
/// Loaded library raw data
objects: BTreeMap<String, Box<[u8]>>,
// Used by link
/// Global symbols
globals: BTreeMap<String, usize>,
/// Weak symbols
weak_syms: BTreeMap<String, usize>,
/// Loaded library in-memory data
mmaps: BTreeMap<String, &'static mut [u8]>,
verbose: bool,
tls_index_offset: usize,
}
impl Linker {
pub fn new(library_path: &str, verbose: bool) -> Self {
Self {
library_path: library_path.to_string(),
objects: BTreeMap::new(),
globals: BTreeMap::new(),
weak_syms: BTreeMap::new(),
mmaps: BTreeMap::new(),
verbose,
tls_index_offset: 0,
}
}
pub fn load(&mut self, name: &str, path: &str) -> Result<()> {
if self.verbose {
println!("load {}: {}", name, path);
}
let mut data = Vec::new();
let path_c = CString::new(path)
.map_err(|err| Error::Malformed(format!("invalid path '{}': {}", path, err)))?;
{
let flags = fcntl::O_RDONLY | fcntl::O_CLOEXEC;
let mut file = File::open(&path_c, flags)
.map_err(|err| Error::Malformed(format!("failed to open '{}': {}", path, err)))?;
file.read_to_end(&mut data)
.map_err(|err| Error::Malformed(format!("failed to read '{}': {}", path, err)))?;
}
self.load_data(name, data.into_boxed_slice())
}
pub fn load_data(&mut self, name: &str, data: Box<[u8]>) -> Result<()> {
//TODO: Prevent failures due to recursion
{
let elf = Elf::parse(&data)?;
//println!("{:#?}", elf);
for library in elf.libraries.iter() {
self.load_library(library)?;
}
}
self.objects.insert(name.to_string(), data);
Ok(())
}
pub fn load_library(&mut self, name: &str) -> Result<()> {
if self.objects.contains_key(name) {
Ok(())
} else if name.contains('/') {
self.load(name, name)
} else {
let library_path = self.library_path.clone();
for part in library_path.split(PATH_SEP) {
let path = if part.is_empty() {
format!("./{}", name)
} else {
format!("{}/{}", part, name)
};
if self.verbose {
println!("check {}", path);
}
let access = unsafe {
let path_c = CString::new(path.as_bytes()).map_err(|err| {
Error::Malformed(format!("invalid path '{}': {}", path, err))
})?;
// TODO: Use R_OK | X_OK
unistd::access(path_c.as_ptr(), unistd::F_OK) == 0
};
if access {
self.load(name, &path)?;
return Ok(());
}
}
Err(Error::Malformed(format!("failed to locate '{}'", name)))
}
}
fn collect_syms(
elf: &Elf,
mmap: &[u8],
verbose: bool,
) -> Result<(BTreeMap<String, usize>, BTreeMap<String, usize>)> {
let mut globals = BTreeMap::new();
let mut weak_syms = BTreeMap::new();
for sym in elf.dynsyms.iter() {
let bind = sym.st_bind();
if sym.st_value == 0 || ![sym::STB_GLOBAL, sym::STB_WEAK].contains(&bind) {
continue;
}
let name: String;
let value: usize;
if let Some(name_res) = elf.dynstrtab.get(sym.st_name) {
name = name_res?.to_string();
value = mmap.as_ptr() as usize + sym.st_value as usize;
} else {
continue;
}
match sym.st_bind() {
sym::STB_GLOBAL => {
if verbose {
println!(" global {}: {:x?} = {:#x}", &name, sym, value);
}
globals.insert(name, value);
}
sym::STB_WEAK => {
if verbose {
println!(" weak {}: {:x?} = {:#x}", &name, sym, value);
}
weak_syms.insert(name, value);
}
_ => unreachable!(),
}
}
return Ok((globals, weak_syms));
}
pub fn get_sym(&self, name: &str) -> Option<usize> {
if let Some(value) = self.globals.get(name) {
if self.verbose {
println!(" sym {} = {:#x}", name, value);
}
Some(*value)
} else if let Some(value) = self.weak_syms.get(name) {
if self.verbose {
println!(" sym {} = {:#x}", name, value);
}
Some(*value)
} else {
if self.verbose {
println!(" sym {} = undefined", name);
}
None
}
}
pub fn link(&mut self, primary_opt: Option<&str>, dso: Option<DSO>) -> Result<Option<usize>> {
unsafe { _r_debug.state = RTLDState::RT_ADD };
_dl_debug_state();
let elfs = {
let mut elfs = BTreeMap::new();
for (name, data) in self.objects.iter() {
// Skip already linked libraries
if !self.mmaps.contains_key(&*name) {
elfs.insert(name.as_str(), Elf::parse(&data)?);
}
}
elfs
};
// Load all ELF files into memory and find all globals
let mut tls_primary = 0;
let mut tls_size = 0;
for (elf_name, elf) in elfs.iter() {
if self.verbose {
println!("map {}", elf_name);
}
let object = match self.objects.get(*elf_name) {
Some(some) => some,
None => continue,
};
// data for struct LinkMap
let mut l_ld = 0;
// Calculate virtual memory bounds
let bounds = {
let mut bounds_opt: Option<(usize, usize)> = None;
for ph in elf.program_headers.iter() {
let voff = ph.p_vaddr as usize % PAGE_SIZE;
let vaddr = ph.p_vaddr as usize - voff;
let vsize =
((ph.p_memsz as usize + voff + PAGE_SIZE - 1) / PAGE_SIZE) * PAGE_SIZE;
match ph.p_type {
program_header::PT_DYNAMIC => {
l_ld = ph.p_vaddr;
}
program_header::PT_LOAD => {
if self.verbose {
println!(" load {:#x}, {:#x}: {:x?}", vaddr, vsize, ph);
}
if let Some(ref mut bounds) = bounds_opt {
if vaddr < bounds.0 {
bounds.0 = vaddr;
}
if vaddr + vsize > bounds.1 {
bounds.1 = vaddr + vsize;
}
} else {
bounds_opt = Some((vaddr, vaddr + vsize));
}
}
program_header::PT_TLS => {
if self.verbose {
println!(" load tls {:#x}: {:x?}", vsize, ph);
}
tls_size += vsize;
if Some(*elf_name) == primary_opt {
tls_primary += vsize;
}
}
_ => (),
}
}
match bounds_opt {
Some(some) => some,
None => continue,
}
};
if self.verbose {
println!(" bounds {:#x}, {:#x}", bounds.0, bounds.1);
}
// Allocate memory
let mmap = unsafe {
let size = bounds.1 /* - bounds.0 */;
let same_elf = if let Some(prog) = dso.as_ref() {
if prog.name == *elf_name {
true
} else {
false
}
} else {
false
};
if same_elf {
let addr = dso.as_ref().unwrap().base_addr;
sys_mman::mprotect(
addr as *mut c_void,
size,
sys_mman::PROT_READ | sys_mman::PROT_WRITE,
);
_r_debug.insert(addr as usize, &elf_name, addr + l_ld as usize);
slice::from_raw_parts_mut(addr as *mut u8, size)
} else {
let ptr = sys_mman::mmap(
ptr::null_mut(),
size,
//TODO: Make it possible to not specify PROT_EXEC on Redox
sys_mman::PROT_READ | sys_mman::PROT_WRITE,
sys_mman::MAP_ANONYMOUS | sys_mman::MAP_PRIVATE,
-1,
0,
);
if ptr as usize == !0
/* MAP_FAILED */
{
return Err(Error::Malformed(format!("failed to map {}", elf_name)));
}
ptr::write_bytes(ptr as *mut u8, 0, size);
_r_debug.insert(ptr as usize, &elf_name, ptr as usize + l_ld as usize);
slice::from_raw_parts_mut(ptr as *mut u8, size)
}
};
if self.verbose {
println!(" mmap {:p}, {:#x}", mmap.as_mut_ptr(), mmap.len());
}
let (globals, weak_syms) = Linker::collect_syms(&elf, &mmap, self.verbose)?;
self.globals.extend(globals.into_iter());
self.weak_syms.extend(weak_syms.into_iter());
self.mmaps.insert(elf_name.to_string(), mmap);
}
// Allocate TLS
let mut tcb_opt = if primary_opt.is_some() {
Some(unsafe { Tcb::new(tls_size)? })
} else {
None
};
if self.verbose {
println!("tcb {:x?}", tcb_opt);
}
// Copy data
let mut tls_offset = tls_primary;
let mut tcb_masters = Vec::new();
// Insert main image master
tcb_masters.push(Master {
ptr: ptr::null_mut(),
len: 0,
offset: 0,
});
let mut tls_ranges = BTreeMap::new();
for (elf_name, elf) in elfs.iter() {
let same_elf = if let Some(prog) = dso.as_ref() {
if prog.name == *elf_name {
true
} else {
false
}
} else {
false
};
if same_elf {
continue;
}
let object = match self.objects.get(*elf_name) {
Some(some) => some,
None => continue,
};
let mmap = match self.mmaps.get_mut(*elf_name) {
Some(some) => some,
None => continue,
};
if self.verbose {
println!("load {}", elf_name);
}
// Copy data
for ph in elf.program_headers.iter() {
let voff = ph.p_vaddr as usize % PAGE_SIZE;
let vaddr = ph.p_vaddr as usize - voff;
let vsize = ((ph.p_memsz as usize + voff + PAGE_SIZE - 1) / PAGE_SIZE) * PAGE_SIZE;
match ph.p_type {
program_header::PT_LOAD => {
let obj_data = {
let range = ph.file_range();
match object.get(range.clone()) {
Some(some) => some,
None => {
return Err(Error::Malformed(format!(
"failed to read {:?}",
range
)))
}
}
};
let mmap_data = {
let range = ph.p_vaddr as usize..ph.p_vaddr as usize + obj_data.len();
match mmap.get_mut(range.clone()) {
Some(some) => some,
None => {
return Err(Error::Malformed(format!(
"failed to write {:?}",
range
)))
}
}
};
if self.verbose {
println!(
" copy {:#x}, {:#x}: {:#x}, {:#x}",
vaddr,
vsize,
voff,
obj_data.len()
);
}
mmap_data.copy_from_slice(obj_data);
}
program_header::PT_TLS => {
let valign = if ph.p_align > 0 {
((ph.p_memsz + (ph.p_align - 1)) / ph.p_align) * ph.p_align
} else {
ph.p_memsz
} as usize;
let mut tcb_master = Master {
ptr: unsafe { mmap.as_ptr().add(ph.p_vaddr as usize) },
len: ph.p_filesz as usize,
offset: tls_size - valign,
};
if self.verbose {
println!(
" tls master {:p}, {:#x}: {:#x}, {:#x}",
tcb_master.ptr, tcb_master.len, tcb_master.offset, valign,
);
}
if Some(*elf_name) == primary_opt {
tls_ranges.insert(
elf_name.to_string(),
(self.tls_index_offset, tcb_master.range()),
);
tcb_masters[0] = tcb_master;
} else {
tcb_master.offset -= tls_offset;
tls_offset += vsize;
tls_ranges.insert(
elf_name.to_string(),
(
self.tls_index_offset + tcb_masters.len(),
tcb_master.range(),
),
);
tcb_masters.push(tcb_master);
}
}
_ => (),
}
}
}
self.tls_index_offset += tcb_masters.len();
// Set master images for TLS and copy TLS data
if let Some(ref mut tcb) = tcb_opt {
unsafe {
tcb.set_masters(tcb_masters.into_boxed_slice());
tcb.copy_masters()?;
}
}
// Perform relocations, and protect pages
for (elf_name, elf) in elfs.iter() {
if self.verbose {
println!("link {}", elf_name);
}
// Relocate
for rel in elf
.dynrelas
.iter()
.chain(elf.dynrels.iter())
.chain(elf.pltrelocs.iter())
{
// println!(" rel {}: {:x?}",
// reloc::r_to_str(rel.r_type, elf.header.e_machine),
// rel
// );
let s = if rel.r_sym > 0 {
let sym = elf.dynsyms.get(rel.r_sym).ok_or(Error::Malformed(format!(
"missing symbol for relocation {:?}",
rel
)))?;
let name =
elf.dynstrtab
.get(sym.st_name)
.ok_or(Error::Malformed(format!(
"missing name for symbol {:?}",
sym
)))??;
self.get_sym(name).unwrap_or(0)
} else {
0
};
let a = rel.r_addend.unwrap_or(0) as usize;
let mmap = match self.mmaps.get_mut(*elf_name) {
Some(some) => some,
None => continue,
};
let b = mmap.as_mut_ptr() as usize;
let (tm, t) = if let Some((tls_index, tls_range)) = tls_ranges.get(*elf_name) {
(*tls_index, tls_range.start)
} else {
(0, 0)
};
let ptr = unsafe { mmap.as_mut_ptr().add(rel.r_offset as usize) };
let set_u64 = |value| {
// println!(" set_u64 {:#x}", value);
unsafe {
*(ptr as *mut u64) = value;
}
};
match rel.r_type {
reloc::R_X86_64_64 => {
set_u64((s + a) as u64);
}
reloc::R_X86_64_DTPMOD64 => {
set_u64(tm as u64);
}
reloc::R_X86_64_DTPOFF64 => {
set_u64((s + a) as u64);
}
reloc::R_X86_64_GLOB_DAT | reloc::R_X86_64_JUMP_SLOT => {
set_u64(s as u64);
}
reloc::R_X86_64_RELATIVE => {
set_u64((b + a) as u64);
}
reloc::R_X86_64_TPOFF64 => {
set_u64((s + a).wrapping_sub(t) as u64);
}
reloc::R_X86_64_IRELATIVE => (), // Handled below
_ => {
panic!(
" {} unsupported",
reloc::r_to_str(rel.r_type, elf.header.e_machine)
);
}
}
}
// overwrite DT_DEBUG if exist in .dynamic section
for section in &elf.section_headers {
// we won't bother with half corrupted elfs.
let name = elf.shdr_strtab.get(section.sh_name).unwrap().unwrap();
if name != ".dynamic" {
continue;
}
let mmap = match self.mmaps.get_mut(*elf_name) {
Some(some) => some,
None => continue,
};
let dyn_start = section.sh_addr as usize;
let bytes: [u8; size_of::<Dyn>() / 2] =
unsafe { transmute((&_r_debug) as *const RTLDDebug as usize) };
if let Some(dynamic) = elf.dynamic.as_ref() {
let mut i = 0;
for entry in &dynamic.dyns {
if entry.d_tag == DT_DEBUG {
let start = dyn_start + i * size_of::<Dyn>() + size_of::<Dyn>() / 2;
mmap[start..start + size_of::<Dyn>() / 2].clone_from_slice(&bytes);
}
i += 1;
}
}
}
// Protect pages
for ph in elf.program_headers.iter() {
if ph.p_type == program_header::PT_LOAD {
let voff = ph.p_vaddr as usize % PAGE_SIZE;
let vaddr = ph.p_vaddr as usize - voff;
let vsize =
((ph.p_memsz as usize + voff + PAGE_SIZE - 1) / PAGE_SIZE) * PAGE_SIZE;
let mut prot = 0;
if ph.p_flags & program_header::PF_R == program_header::PF_R {
prot |= sys_mman::PROT_READ;
}
// W ^ X. If it is executable, do not allow it to be writable, even if requested
if ph.p_flags & program_header::PF_X == program_header::PF_X {
prot |= sys_mman::PROT_EXEC;
} else if ph.p_flags & program_header::PF_W == program_header::PF_W {
prot |= sys_mman::PROT_WRITE;
}
let mmap = match self.mmaps.get_mut(*elf_name) {
Some(some) => some,
None => continue,
};
let res = unsafe {
let ptr = mmap.as_mut_ptr().add(vaddr);
if self.verbose {
println!(" prot {:#x}, {:#x}: {:p}, {:#x}", vaddr, vsize, ptr, prot);
}
sys_mman::mprotect(ptr as *mut c_void, vsize, prot)
};
if res < 0 {
return Err(Error::Malformed(format!("failed to mprotect {}", elf_name)));
}
}
}
}
// Activate TLS
if let Some(ref mut tcb) = tcb_opt {
unsafe {
tcb.activate();
}
}
// Perform indirect relocations (necessary evil), gather entry point
let mut entry_opt = None;
for (elf_name, elf) in elfs.iter() {
let mmap = match self.mmaps.get_mut(*elf_name) {
Some(some) => some,
None => continue,
};
if self.verbose {
println!("entry {}", elf_name);
}
if Some(*elf_name) == primary_opt {
entry_opt = Some(mmap.as_mut_ptr() as usize + elf.header.e_entry as usize);
}
// Relocate
for rel in elf
.dynrelas
.iter()
.chain(elf.dynrels.iter())
.chain(elf.pltrelocs.iter())
{
// println!(" rel {}: {:x?}",
// reloc::r_to_str(rel.r_type, elf.header.e_machine),
// rel
// );
let a = rel.r_addend.unwrap_or(0) as usize;
let b = mmap.as_mut_ptr() as usize;
let ptr = unsafe { mmap.as_mut_ptr().add(rel.r_offset as usize) };
let set_u64 = |value| {
// println!(" set_u64 {:#x}", value);
unsafe {
*(ptr as *mut u64) = value;
}
};
if rel.r_type == reloc::R_X86_64_IRELATIVE {
unsafe {
let f: unsafe extern "C" fn() -> u64 = transmute(b + a);
set_u64(f());
}
}
}
// Protect pages
for ph in elf.program_headers.iter() {
if let program_header::PT_LOAD = ph.p_type {
let voff = ph.p_vaddr as usize % PAGE_SIZE;
let vaddr = ph.p_vaddr as usize - voff;
let vsize =
((ph.p_memsz as usize + voff + PAGE_SIZE - 1) / PAGE_SIZE) * PAGE_SIZE;
let mut prot = 0;
if ph.p_flags & program_header::PF_R == program_header::PF_R {
prot |= sys_mman::PROT_READ;
}
// W ^ X. If it is executable, do not allow it to be writable, even if requested
if ph.p_flags & program_header::PF_X == program_header::PF_X {
prot |= sys_mman::PROT_EXEC;
} else if ph.p_flags & program_header::PF_W == program_header::PF_W {
prot |= sys_mman::PROT_WRITE;
}
let res = unsafe {
let ptr = mmap.as_mut_ptr().add(vaddr);
if self.verbose {
println!(" prot {:#x}, {:#x}: {:p}, {:#x}", vaddr, vsize, ptr, prot);
}
sys_mman::mprotect(ptr as *mut c_void, vsize, prot)
};
if res < 0 {
return Err(Error::Malformed(format!("failed to mprotect {}", elf_name)));
}
}
}
}
unsafe { _r_debug.state = RTLDState::RT_CONSISTENT };
_dl_debug_state();
Ok(entry_opt)
}
}