Jeremy Soller
67 lines
2.2 KiB
Rust
67 lines
2.2 KiB
Rust
use crate::{
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arch::{gdt, interrupt::InterruptStack},
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context, ptrace, syscall,
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syscall::flag::{PTRACE_FLAG_IGNORE, PTRACE_STOP_POST_SYSCALL, PTRACE_STOP_PRE_SYSCALL},
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};
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use core::mem::offset_of;
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use x86::{bits32::task::TaskStateSegment, msr, segmentation::SegmentSelector};
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pub unsafe fn init() {}
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macro_rules! with_interrupt_stack {
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(|$stack:ident| $code:block) => {{
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let allowed = ptrace::breakpoint_callback(PTRACE_STOP_PRE_SYSCALL, None)
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.and_then(|_| ptrace::next_breakpoint().map(|f| !f.contains(PTRACE_FLAG_IGNORE)));
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if allowed.unwrap_or(true) {
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// If the syscall is `clone`, the clone won't return here. Instead,
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// it'll return early and leave any undropped values. This is
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// actually GOOD, because any references are at that point UB
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// anyway, because they are based on the wrong stack.
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let $stack = &mut *$stack;
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(*$stack).scratch.eax = $code;
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}
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ptrace::breakpoint_callback(PTRACE_STOP_POST_SYSCALL, None);
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}};
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}
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interrupt_stack!(syscall, |stack| {
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with_interrupt_stack!(|stack| {
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let scratch = &stack.scratch;
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let preserved = &stack.preserved;
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syscall::syscall(
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scratch.eax,
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preserved.ebx,
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scratch.ecx,
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scratch.edx,
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preserved.esi,
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preserved.edi,
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stack,
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)
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})
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});
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#[naked]
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pub unsafe extern "C" fn clone_ret() {
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core::arch::asm!(
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concat!(
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// The address of this instruction is injected by `clone` in process.rs, on
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// top of the stack syscall->inner in this file, which is done using the ebp
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// register we save there.
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//
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// The top of our stack here is the address pointed to by ebp, which is:
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//
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// - the previous ebp
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// - the return location
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//
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// Our goal is to return from the parent function, inner, so we restore
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// ebp...
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"pop ebp\n",
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// ...and we return to the address at the top of the stack
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"ret\n",
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),
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options(noreturn)
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);
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}
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