From 61fcc018fcf5f154f3eb0532a589745febe84e62 Mon Sep 17 00:00:00 2001
From: oddcoder <ahmedsoliman@oddcoder.com>
Date: Mon, 10 Aug 2020 23:22:17 +0200
Subject: [PATCH] Refer to libraries with soname if available and avoid loading
libs twice
It is usually not optimal to load a library twice and for specifics,
it is **terrible** idea to load libc twice it was enough trouble
dealing with libc statically linked into ld.so. So What this patch does
it check for soname and if a library is already loaded it won't get
loaded again. Why soname ? because unfortunately some bins gets linked
againt libc.so while of their dependencies gets linked against
libc.so.6 while one is usually symbolic link for the other.
---
src/ld_so/linker.rs | 79 ++++++++++++++++++++++++++++++---------------
1 file changed, 53 insertions(+), 26 deletions(-)
diff --git a/src/ld_so/linker.rs b/src/ld_so/linker.rs
index c55e4a7d..34030513 100644
--- a/src/ld_so/linker.rs
+++ b/src/ld_so/linker.rs
@@ -15,9 +15,7 @@ use goblin::{
header::ET_DYN,
program_header,
r#dyn::{Dyn, DT_DEBUG},
- reloc,
- sym,
- Elf,
+ reloc, sym, Elf,
},
error::{Error, Result},
};
@@ -25,7 +23,7 @@ use goblin::{
use crate::{
c_str::CString,
fs::File,
- header::{fcntl, sys_mman, unistd, errno::STR_ERROR},
+ header::{errno::STR_ERROR, fcntl, sys_mman, unistd},
io::Read,
platform::{errno, types::c_void},
};
@@ -147,9 +145,14 @@ impl Linker {
deps.push(dep);
}
}
-
- lib.objects.insert(name.to_string(), data);
-
+ let elf = Elf::parse(&data)?;
+ let key = match elf.soname {
+ Some(soname) => soname,
+ _ => name,
+ };
+ if !lib.objects.contains_key(key) {
+ lib.objects.insert(key.to_string(), data);
+ }
return Ok(deps);
}
@@ -471,11 +474,19 @@ impl Linker {
-1,
0,
);
- if ptr as usize == !0 /* MAP_FAILED */ {
- return Err(Error::Malformed(format!("failed to map {}. errno: {}", elf_name, STR_ERROR[errno as usize])));
+ if ptr as usize == !0
+ /* MAP_FAILED */
+ {
+ return Err(Error::Malformed(format!(
+ "failed to map {}. errno: {}",
+ elf_name, STR_ERROR[errno as usize]
+ )));
}
if start as *mut c_void != ptr::null_mut() {
- assert_eq!(ptr, start as *mut c_void, "mmap must always map on the destination we requested");
+ assert_eq!(
+ ptr, start as *mut c_void,
+ "mmap must always map on the destination we requested"
+ );
}
}
start = addr + vaddr + vsize
@@ -486,7 +497,10 @@ impl Linker {
sys_mman::PROT_READ | sys_mman::PROT_WRITE,
);
_r_debug.insert_first(addr as usize, &elf_name, addr + l_ld as usize);
- (addr as usize, slice::from_raw_parts_mut(addr as *mut u8, size))
+ (
+ addr as usize,
+ slice::from_raw_parts_mut(addr as *mut u8, size),
+ )
} else {
let (start, end) = bounds;
let size = end - start;
@@ -504,11 +518,19 @@ impl Linker {
-1,
0,
);
- if ptr as usize == !0 /* MAP_FAILED */ {
- return Err(Error::Malformed(format!("failed to map {}. errno: {}", elf_name, STR_ERROR[errno as usize])));
+ if ptr as usize == !0
+ /* MAP_FAILED */
+ {
+ return Err(Error::Malformed(format!(
+ "failed to map {}. errno: {}",
+ elf_name, STR_ERROR[errno as usize]
+ )));
}
if start as *mut c_void != ptr::null_mut() {
- assert_eq!(ptr, start as *mut c_void, "mmap must always map on the destination we requested");
+ assert_eq!(
+ ptr, start as *mut c_void,
+ "mmap must always map on the destination we requested"
+ );
}
ptr::write_bytes(ptr as *mut u8, 0, size);
_r_debug.insert(ptr as usize, &elf_name, ptr as usize + l_ld as usize);
@@ -590,7 +612,8 @@ impl Linker {
};
let mmap_data = {
- let range = ph.p_vaddr as usize - base_addr..ph.p_vaddr as usize + obj_data.len() - base_addr;
+ let range = ph.p_vaddr as usize - base_addr
+ ..ph.p_vaddr as usize + obj_data.len() - base_addr;
match mmap.get_mut(range.clone()) {
Some(some) => some,
None => {
@@ -598,7 +621,7 @@ impl Linker {
return Err(Error::Malformed(format!(
"failed to write {:x?}",
range
- )))
+ )));
}
}
};
@@ -690,18 +713,20 @@ impl Linker {
let name =
elf.dynstrtab
- .get(sym.st_name)
- .ok_or(Error::Malformed(format!(
- "missing name for symbol {:?}",
- sym
- )))??;
- lib.get_sym(name)
- .or_else(|| self.root.get_sym(name))
+ .get(sym.st_name)
+ .ok_or(Error::Malformed(format!(
+ "missing name for symbol {:?}",
+ sym
+ )))??;
+ lib.get_sym(name).or_else(|| self.root.get_sym(name))
} else {
None
};
- let s = symbol.as_ref().map(|sym| sym.as_ptr() as usize).unwrap_or(0);
+ let s = symbol
+ .as_ref()
+ .map(|sym| sym.as_ptr() as usize)
+ .unwrap_or(0);
let a = rel.r_addend.unwrap_or(0) as usize;
@@ -757,9 +782,11 @@ impl Linker {
reloc::R_X86_64_IRELATIVE => (), // Handled below
reloc::R_X86_64_COPY => unsafe {
// TODO: Make this work
- let sym = symbol.as_ref().expect("R_X86_64_COPY called without valid symbol");
+ let sym = symbol
+ .as_ref()
+ .expect("R_X86_64_COPY called without valid symbol");
ptr::copy_nonoverlapping(sym.as_ptr() as *const u8, ptr, sym.size as usize);
- }
+ },
_ => {
panic!(
" {} unsupported",
--
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