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Initial forward-edge CFI implementation (#3693)

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* Initial forward-edge CFI implementation

Give the user the option to start all basic blocks that are targets
of indirect branches with the BTI instruction introduced by the
Branch Target Identification extension to the Arm instruction set
architecture.

Copyright (c) 2022, Arm Limited.

* Refactor `from_artifacts` to avoid second `make_executable` (#1)

This involves "parsing" twice but this is parsing just the header of an
ELF file so it's not a very intensive operation and should be ok to do
twice.

* Address the code review feedback

Copyright (c) 2022, Arm Limited.

Co-authored-by: Alex Crichton <alex@alexcrichton.com>
This commit is contained in:
Anton Kirilov
2022-09-08 15:35:58 +01:00
committed by GitHub
parent caad14826c
commit d8b290898c
32 changed files with 441 additions and 105 deletions
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34
crates/runtime/src/mmap.rs
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@@ -412,7 +412,11 @@ impl Mmap {
}
/// Makes the specified `range` within this `Mmap` to be read/execute.
pub unsafe fn make_executable(&self, range: Range<usize>) -> Result<()> {
pub unsafe fn make_executable(
&self,
range: Range<usize>,
enable_branch_protection: bool,
) -> Result<()> {
assert!(range.start <= self.len());
assert!(range.end <= self.len());
assert!(range.start <= range.end);
@@ -428,8 +432,15 @@ impl Mmap {
use std::io;
use windows_sys::Win32::System::Memory::*;
let flags = if enable_branch_protection {
// TODO: We use this check to avoid an unused variable warning,
// but some of the CFG-related flags might be applicable
PAGE_EXECUTE_READ
} else {
PAGE_EXECUTE_READ
};
let mut old = 0;
let result = VirtualProtect(base, len, PAGE_EXECUTE_READ, &mut old);
let result = VirtualProtect(base, len, flags, &mut old);
if result == 0 {
return Err(io::Error::last_os_error().into());
}
@@ -438,8 +449,25 @@ impl Mmap {
#[cfg(not(windows))]
{
use rustix::mm::{mprotect, MprotectFlags};
mprotect(base, len, MprotectFlags::READ | MprotectFlags::EXEC)?;
let flags = MprotectFlags::READ | MprotectFlags::EXEC;
let flags = if enable_branch_protection {
#[cfg(all(target_arch = "aarch64", target_os = "linux"))]
if std::arch::is_aarch64_feature_detected!("bti") {
MprotectFlags::from_bits_unchecked(flags.bits() | /* PROT_BTI */ 0x10)
} else {
flags
}
#[cfg(not(all(target_arch = "aarch64", target_os = "linux")))]
flags
} else {
flags
};
mprotect(base, len, flags)?;
}
Ok(())
}