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WIP: Let userspace manage fsbase/gsbase and TLS.

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This commit is contained in:
4lDO2
2021-08-01 12:09:22 +02:00
parent 0968e4f87e
commit 3eedbeb14d
13 changed files with 283 additions and 214 deletions
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src/scheme/mod.rs
+2
View File
@@ -137,6 +137,7 @@ impl SchemeList {
//TODO: Only memory: is in the null namespace right now. It should be removed when
//anonymous mmap's are implemented
self.insert(ns, "memory", |_| Arc::new(MemoryScheme::new())).unwrap();
self.insert(ns, "thisproc", |_| Arc::new(ProcScheme::restricted())).unwrap();
}
/// Initialize a new namespace
@@ -168,6 +169,7 @@ impl SchemeList {
self.insert(ns, "initfs", |_| Arc::new(InitFsScheme::new())).unwrap();
self.insert(ns, "irq", |scheme_id| Arc::new(IrqScheme::new(scheme_id))).unwrap();
self.insert(ns, "proc", |scheme_id| Arc::new(ProcScheme::new(scheme_id))).unwrap();
self.insert(ns, "thisproc", |_| Arc::new(ProcScheme::restricted())).unwrap();
self.insert(ns, "serio", |scheme_id| Arc::new(SerioScheme::new(scheme_id))).unwrap();
#[cfg(feature = "live")] {
src/scheme/proc.rs
+122 -7
View File
@@ -6,6 +6,7 @@ use crate::{
syscall::{
FloatRegisters,
IntRegisters,
EnvRegisters,
data::{PtraceEvent, Stat},
error::*,
flag::*,
@@ -57,6 +58,9 @@ fn try_stop_context<F, T>(pid: ContextId, mut callback: F) -> Result<T>
where
F: FnMut(&mut Context) -> Result<T>,
{
if pid == context::context_id() {
return Err(Error::new(EBADF));
}
// Stop process
let (was_stopped, mut running) = with_context_mut(pid, |context| {
let was_stopped = context.ptrace_stop;
@@ -88,7 +92,8 @@ where
#[derive(Clone, Copy, PartialEq, Eq)]
enum RegsKind {
Float,
Int
Int,
Env,
}
#[derive(Clone, Copy, PartialEq, Eq)]
enum Operation {
@@ -195,6 +200,12 @@ pub static PROC_SCHEME_ID: AtomicSchemeId = AtomicSchemeId::default();
pub struct ProcScheme {
next_id: AtomicUsize,
handles: RwLock<BTreeMap<usize, Handle>>,
access: Access,
}
#[derive(PartialEq)]
pub enum Access {
OtherProcesses,
Restricted,
}
impl ProcScheme {
@@ -204,6 +215,14 @@ impl ProcScheme {
Self {
next_id: AtomicUsize::new(0),
handles: RwLock::new(BTreeMap::new()),
access: Access::OtherProcesses,
}
}
pub fn restricted() -> Self {
Self {
next_id: AtomicUsize::new(0),
handles: RwLock::new(BTreeMap::new()),
access: Access::Restricted,
}
}
}
@@ -211,15 +230,22 @@ impl ProcScheme {
impl Scheme for ProcScheme {
fn open(&self, path: &str, flags: usize, uid: u32, gid: u32) -> Result<usize> {
let mut parts = path.splitn(2, '/');
let pid = parts.next()
.and_then(|s| s.parse().ok())
.map(ContextId::from)
.ok_or(Error::new(EINVAL))?;
let pid_str = parts.next()
.ok_or(Error::new(ENOENT))?;
let pid = if pid_str == "current" {
context::context_id()
} else if self.access == Access::Restricted {
return Err(Error::new(EACCES));
} else {
ContextId::from(pid_str.parse().map_err(|_| Error::new(ENOENT))?)
};
let operation = match parts.next() {
Some("mem") => Operation::Memory,
Some("regs/float") => Operation::Regs(RegsKind::Float),
Some("regs/int") => Operation::Regs(RegsKind::Int),
Some("regs/env") => Operation::Regs(RegsKind::Env),
Some("trace") => Operation::Trace,
Some("exe") => Operation::Static("exe"),
_ => return Err(Error::new(EINVAL))
@@ -382,7 +408,8 @@ impl Scheme for ProcScheme {
Operation::Regs(kind) => {
union Output {
float: FloatRegisters,
int: IntRegisters
int: IntRegisters,
env: EnvRegisters,
}
let (output, size) = match kind {
@@ -406,7 +433,37 @@ impl Scheme for ProcScheme {
stack.save(&mut regs);
Ok((Output { int: regs }, mem::size_of::<IntRegisters>()))
}
})?
})?,
RegsKind::Env => {
let (fsbase, gsbase) = if info.pid == context::context_id() {
#[cfg(not(feature = "x86_fsgsbase"))]
unsafe {
(
x86::msr::rdmsr(x86::msr::IA32_FS_BASE),
x86::msr::rdmsr(x86::msr::IA32_KERNEL_GSBASE),
)
}
#[cfg(feature = "x86_fsgsbase")]
unsafe {
use x86::bits64::segmentation::*;
(
rdfsbase(),
{
swapgs();
let gsbase = rdgsbase();
swapgs();
gsbase
}
)
}
} else {
try_stop_context(info.pid, |context| {
Ok((context.arch.fsbase as u64, context.arch.gsbase as u64))
})?
};
(Output { env: EnvRegisters { fsbase, gsbase }}, mem::size_of::<EnvRegisters>())
}
};
let bytes = unsafe {
@@ -503,6 +560,9 @@ impl Scheme for ProcScheme {
if buf.len() < mem::size_of::<FloatRegisters>() {
return Ok(0);
}
if (buf.as_ptr() as usize) % mem::align_of::<FloatRegisters>() != 0 {
return Err(Error::new(EINVAL));
}
let regs = unsafe {
*(buf as *const _ as *const FloatRegisters)
};
@@ -521,6 +581,9 @@ impl Scheme for ProcScheme {
if buf.len() < mem::size_of::<IntRegisters>() {
return Ok(0);
}
if (buf.as_ptr() as usize) % mem::align_of::<FloatRegisters>() != 0 {
return Err(Error::new(EINVAL));
}
let regs = unsafe {
*(buf as *const _ as *const IntRegisters)
};
@@ -537,6 +600,57 @@ impl Scheme for ProcScheme {
}
})
}
RegsKind::Env => {
if buf.len() < mem::size_of::<EnvRegisters>() {
return Ok(0);
}
if (buf.as_ptr() as usize) % mem::align_of::<EnvRegisters>() != 0 {
return Err(Error::new(EINVAL));
}
let regs = unsafe {
*(buf as *const _ as *const EnvRegisters)
};
use rmm::{Arch as _, X8664Arch};
if !(X8664Arch::virt_is_valid(VirtualAddress::new(regs.fsbase as usize)) && X8664Arch::virt_is_valid(VirtualAddress::new(regs.gsbase as usize))) {
return Err(Error::new(EINVAL));
}
if info.pid == context::context_id() {
#[cfg(not(feature = "x86_fsgsbase"))]
unsafe {
x86::msr::wrmsr(x86::msr::IA32_FS_BASE, regs.fsbase);
// We have to write to KERNEL_GSBASE, because when the kernel returns to
// userspace, it will have executed SWAPGS first.
x86::msr::wrmsr(x86::msr::IA32_KERNEL_GSBASE, regs.gsbase);
match context::contexts().current().ok_or(Error::new(ESRCH))?.write().arch {
ref mut arch => {
arch.fsbase = regs.fsbase as usize;
arch.gsbase = regs.gsbase as usize;
}
}
}
#[cfg(feature = "x86_fsgsbase")]
unsafe {
use x86::bits64::segmentation::*;
wrfsbase(regs.fsbase);
swapgs();
wrgsbase(regs.gsbase);
swapgs();
// No need to update the current context; with fsgsbase enabled, these
// registers are automatically saved and restored.
}
} else {
try_stop_context(info.pid, |context| {
context.arch.fsbase = regs.fsbase as usize;
context.arch.gsbase = regs.gsbase as usize;
Ok(())
})?;
}
Ok(mem::size_of::<EnvRegisters>())
}
},
Operation::Trace => {
if buf.len() < mem::size_of::<u64>() {
@@ -621,6 +735,7 @@ impl Scheme for ProcScheme {
Operation::Memory => "mem",
Operation::Regs(RegsKind::Float) => "regs/float",
Operation::Regs(RegsKind::Int) => "regs/int",
Operation::Regs(RegsKind::Env) => "regs/env",
Operation::Trace => "trace",
Operation::Static(path) => path,
});