111 lines
3.1 KiB
Rust
111 lines
3.1 KiB
Rust
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use std::error::Error;
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use libloading::os::unix::{Library, Symbol};
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use retour::Function;
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use tracing::warn;
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use crate::tricks::find_argv0;
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pub fn find_symbol<T : Function>(name: &str) -> Result<Option<T>, Box<dyn Error>> {
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// try to find it among exported symbols
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let this = Library::this(); // TODO don't reopen it every time
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let sym : Result<Symbol<T>, libloading::Error> = unsafe { this.get(name.as_bytes()) };
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if let Ok(s) = sym {
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return Ok(Some(*s));
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}
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// try to read it from executable's elf
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match find_argv0() {
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None => warn!("could not find argv0 for process"),
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Some(exec) => match procmaps::map_addr_path(&exec)? {
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None => warn!("could not find base addr of process image"),
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Some((base, path)) => match exec::offset_in_elf(&path, &name)? {
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None => warn!("could not locate requested symbol in ELF"),
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Some(offset) => {
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let addr : *const () = (base + offset) as *const ();
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return Ok(Some(unsafe { Function::from_ptr(addr) } ));
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}
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}
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}
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}
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Ok(None)
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}
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pub mod exec {
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use std::path::Path;
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use elf::{ParseError, ElfBytes, endian::AnyEndian};
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use tracing::{warn, debug};
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pub fn offset_in_elf(path: &Path, symbol: &str) -> Result<Option<usize>, ParseError> {
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let exec_data = std::fs::read(path)?;
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let headers = ElfBytes::<AnyEndian>::minimal_parse(&exec_data)?;
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let common = headers.find_common_data()?;
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// first try with hash table
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match common.sysv_hash {
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None => warn!("missing symbols hash table in ELF"),
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Some(sysv_hash) => match common.dynsyms {
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None => warn!("missing dynamic symbols in ELF"),
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Some(dynsyms) => match common.dynsyms_strs {
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None => warn!("missing string tab for dynamic symbols in ELF"),
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Some(dynsyms_strs) => match sysv_hash.find(symbol.as_bytes(), &dynsyms, &dynsyms_strs)? {
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None => debug!("could not find symbol {} in ELF hashmap", symbol),
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Some((_id, sym)) => return Ok(Some(sym.st_value as usize)),
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},
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},
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},
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}
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// fall back to iterating symbols table
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match common.symtab {
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None => warn!("missing symbols table in ELF"),
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Some(symtab) => match common.symtab_strs {
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None => warn!("missing names for symbols in ELF"),
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Some(symtab_strs) => {
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for sym in symtab {
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let name = symtab_strs.get(sym.st_name as usize)?;
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if name == symbol {
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return Ok(Some(sym.st_value as usize));
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}
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}
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debug!("no symbol matched '{}'", symbol);
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}
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}
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}
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Ok(None)
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}
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}
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pub mod procmaps {
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use std::path::PathBuf;
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use proc_maps::get_process_maps;
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use tracing::{debug, warn};
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use crate::tricks::fmt_path;
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pub fn map_addr_path(name: &str) -> std::io::Result<Option<(usize, PathBuf)>> {
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let proc_maps = get_process_maps(std::process::id() as i32)?;
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for map in proc_maps {
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debug!("map > 0x{:08X} {} [{:x}] - {} [{}]", map.start(), map.flags, map.offset, map.inode, fmt_path(map.filename()));
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if map.is_exec() {
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if let Some(path) = map.filename() {
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if path.ends_with(name) {
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return Ok(Some((map.start() - map.offset, map.filename().unwrap().to_path_buf())));
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}
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}
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}
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}
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warn!("could not find address of '{}'", name);
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Ok(None)
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}
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}
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