Files
redox-kernel/src/syscall/process.rs
2021-04-28 20:04:27 -06:00

1665 lines
60 KiB
Rust

use alloc::{
boxed::Box,
collections::BTreeSet,
string::String,
sync::Arc,
vec::Vec,
};
use core::alloc::{GlobalAlloc, Layout};
use core::ops::DerefMut;
use core::{intrinsics, mem};
use spin::RwLock;
use crate::context::file::FileDescriptor;
use crate::context::{ContextId, WaitpidKey};
use crate::context::memory::{UserGrants, Region};
use crate::context;
#[cfg(not(feature="doc"))]
use crate::elf::{self, program_header};
use crate::interrupt;
use crate::ipi::{ipi, IpiKind, IpiTarget};
use crate::memory::allocate_frames;
use crate::paging::entry::EntryFlags;
use crate::paging::mapper::MapperFlushAll;
use crate::paging::temporary_page::TemporaryPage;
use crate::paging::{ActivePageTable, InactivePageTable, PageTableType, Page, VirtualAddress, PAGE_SIZE};
use crate::{ptrace, syscall};
use crate::scheme::FileHandle;
use crate::start::usermode;
use crate::syscall::data::{SigAction, Stat};
use crate::syscall::error::*;
use crate::syscall::flag::{wifcontinued, wifstopped, AT_ENTRY, AT_NULL, AT_PHDR, CloneFlags,
CLONE_FILES, CLONE_FS, CLONE_SIGHAND, CLONE_STACK, CLONE_VFORK, CLONE_VM,
MapFlags, PROT_EXEC, PROT_READ, PROT_WRITE, PTRACE_EVENT_CLONE,
PTRACE_STOP_EXIT, SigActionFlags, SIG_BLOCK, SIG_DFL, SIG_SETMASK, SIG_UNBLOCK,
SIGCONT, SIGTERM, WaitFlags, WCONTINUED, WNOHANG, WUNTRACED};
use crate::syscall::ptrace_event;
use crate::syscall::validate::{validate_slice, validate_slice_mut};
pub fn clone(flags: CloneFlags, stack_base: usize) -> Result<ContextId> {
let ppid;
let pid;
{
let pgid;
let ruid;
let rgid;
let rns;
let euid;
let egid;
let ens;
let umask;
let sigmask;
let cpu_id_opt = None;
let arch;
let vfork;
let mut kfx_opt = None;
let mut kstack_opt = None;
let mut offset = 0;
let mut image = vec![];
let mut stack_opt = None;
let mut sigstack_opt = None;
let mut tls_opt = None;
let grants;
let name;
let cwd;
let files;
let actions;
// Copy from old process
{
let contexts = context::contexts();
let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
let context = context_lock.read();
ppid = context.id;
pgid = context.pgid;
ruid = context.ruid;
rgid = context.rgid;
rns = context.rns;
euid = context.euid;
egid = context.egid;
ens = context.ens;
sigmask = context.sigmask;
umask = context.umask;
// Uncomment to disable threads on different CPUs
// if flags.contains(CLONE_VM) {
// cpu_id_opt = context.cpu_id;
// }
arch = context.arch.clone();
if let Some(ref fx) = context.kfx {
let mut new_fx = unsafe { Box::from_raw(crate::ALLOCATOR.alloc(Layout::from_size_align_unchecked(1024, 16)) as *mut [u8; 1024]) };
for (new_b, b) in new_fx.iter_mut().zip(fx.iter()) {
*new_b = *b;
}
kfx_opt = Some(new_fx);
}
#[cfg(target_arch = "x86_64")]
{
if let Some(ref stack) = context.kstack {
// Get the relative offset to the return address of the function
// obtaining `stack_base`.
//
// (base pointer - start of stack) - one
offset = stack_base - stack.as_ptr() as usize - mem::size_of::<usize>(); // Add clone ret
let mut new_stack = stack.clone();
unsafe {
// Set clone's return value to zero. This is done because
// the clone won't return like normal, which means the value
// would otherwise never get set.
if let Some(regs) = ptrace::rebase_regs_ptr_mut(context.regs, Some(&mut new_stack)) {
(*regs).scratch.rax = 0;
}
// Change the return address of the child (previously
// syscall) to the arch-specific clone_ret callback
let func_ptr = new_stack.as_mut_ptr().add(offset);
*(func_ptr as *mut usize) = interrupt::syscall::clone_ret as usize;
}
kstack_opt = Some(new_stack);
}
}
#[cfg(target_arch = "aarch64")]
{
if let Some(ref stack) = context.kstack {
offset = stack_base - stack.as_ptr() as usize;
let mut new_stack = stack.clone();
kstack_opt = Some(new_stack);
}
}
if flags.contains(CLONE_VM) {
for memory_shared in context.image.iter() {
image.push(memory_shared.clone());
}
} else {
for memory_shared in context.image.iter() {
memory_shared.with(|memory| {
let mut new_memory = context::memory::Memory::new(
VirtualAddress::new(memory.start_address().data() + crate::USER_TMP_OFFSET),
memory.size(),
EntryFlags::PRESENT | EntryFlags::NO_EXECUTE | EntryFlags::WRITABLE,
false
);
unsafe {
intrinsics::copy(memory.start_address().data() as *const u8,
new_memory.start_address().data() as *mut u8,
memory.size());
}
new_memory.remap(memory.flags());
image.push(new_memory.to_shared());
});
}
}
if let Some(ref stack_shared) = context.stack {
if flags.contains(CLONE_STACK) {
stack_opt = Some(stack_shared.clone());
} else {
stack_shared.with(|stack| {
let mut new_stack = context::memory::Memory::new(
VirtualAddress::new(crate::USER_TMP_STACK_OFFSET),
stack.size(),
EntryFlags::PRESENT | EntryFlags::NO_EXECUTE | EntryFlags::WRITABLE,
false
);
unsafe {
intrinsics::copy(stack.start_address().data() as *const u8,
new_stack.start_address().data() as *mut u8,
stack.size());
}
new_stack.remap(stack.flags());
stack_opt = Some(new_stack.to_shared());
});
}
}
if let Some(ref sigstack) = context.sigstack {
let mut new_sigstack = context::memory::Memory::new(
VirtualAddress::new(crate::USER_TMP_SIGSTACK_OFFSET),
sigstack.size(),
EntryFlags::PRESENT | EntryFlags::NO_EXECUTE | EntryFlags::WRITABLE,
false
);
unsafe {
intrinsics::copy(sigstack.start_address().data() as *const u8,
new_sigstack.start_address().data() as *mut u8,
sigstack.size());
}
new_sigstack.remap(sigstack.flags());
sigstack_opt = Some(new_sigstack);
}
if let Some(ref tls) = context.tls {
let mut new_tls = context::memory::Tls {
master: tls.master,
file_size: tls.file_size,
mem: context::memory::Memory::new(
VirtualAddress::new(crate::USER_TMP_TLS_OFFSET),
tls.mem.size(),
EntryFlags::PRESENT | EntryFlags::NO_EXECUTE | EntryFlags::WRITABLE,
true
),
offset: tls.offset,
};
if flags.contains(CLONE_VM) {
unsafe {
new_tls.load();
}
} else {
unsafe {
intrinsics::copy(tls.mem.start_address().data() as *const u8,
new_tls.mem.start_address().data() as *mut u8,
tls.mem.size());
}
}
new_tls.mem.remap(tls.mem.flags());
tls_opt = Some(new_tls);
}
if flags.contains(CLONE_VM) {
grants = Arc::clone(&context.grants);
} else {
let mut grants_set = UserGrants::default();
for grant in context.grants.read().iter() {
let start = VirtualAddress::new(grant.start_address().data() + crate::USER_TMP_GRANT_OFFSET - crate::USER_GRANT_OFFSET);
grants_set.insert(grant.secret_clone(start));
}
grants = Arc::new(RwLock::new(grants_set));
}
if flags.contains(CLONE_VM) {
name = Arc::clone(&context.name);
} else {
name = Arc::new(RwLock::new(context.name.read().clone()));
}
if flags.contains(CLONE_FS) {
cwd = Arc::clone(&context.cwd);
} else {
cwd = Arc::new(RwLock::new(context.cwd.read().clone()));
}
if flags.contains(CLONE_FILES) {
files = Arc::clone(&context.files);
} else {
files = Arc::new(RwLock::new(context.files.read().clone()));
}
if flags.contains(CLONE_SIGHAND) {
actions = Arc::clone(&context.actions);
} else {
actions = Arc::new(RwLock::new(context.actions.read().clone()));
}
}
// If not cloning files, dup to get a new number from scheme
// This has to be done outside the context lock to prevent deadlocks
if !flags.contains(CLONE_FILES) {
for (_fd, file_opt) in files.write().iter_mut().enumerate() {
let new_file_opt = if let Some(ref file) = *file_opt {
Some(FileDescriptor {
description: Arc::clone(&file.description),
cloexec: file.cloexec,
})
} else {
None
};
*file_opt = new_file_opt;
}
}
// If not cloning virtual memory, use fmap to re-obtain every grant where possible
if !flags.contains(CLONE_VM) {
let mut grants = grants.write();
let mut to_remove = BTreeSet::new();
// TODO: Use drain_filter if possible
for grant in grants.iter() {
let remove = false;
if let Some(ref _desc) = grant.desc_opt {
println!("todo: clone grant using fmap: {:?}", grant);
}
if remove {
to_remove.insert(Region::from(grant));
}
}
for region in to_remove {
grants.remove(&region);
}
}
// If vfork, block the current process
// This has to be done after the operations that may require context switches
if flags.contains(CLONE_VFORK) {
let contexts = context::contexts();
let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
let mut context = context_lock.write();
context.block("vfork");
vfork = true;
} else {
vfork = false;
}
// Set up new process
{
let mut contexts = context::contexts_mut();
let context_lock = contexts.new_context()?;
let mut context = context_lock.write();
pid = context.id;
context.pgid = pgid;
context.ppid = ppid;
context.ruid = ruid;
context.rgid = rgid;
context.rns = rns;
context.euid = euid;
context.egid = egid;
context.ens = ens;
context.sigmask = sigmask;
context.umask = umask;
//TODO: Better CPU balancing
if let Some(cpu_id) = cpu_id_opt {
context.cpu_id = Some(cpu_id);
} else {
context.cpu_id = Some(pid.into() % crate::cpu_count());
}
context.status = context::Status::Runnable;
context.vfork = vfork;
context.arch = arch;
let mut active_utable = unsafe { ActivePageTable::new(PageTableType::User) };
let mut active_ktable = unsafe { ActivePageTable::new(PageTableType::Kernel) };
let mut temporary_upage = TemporaryPage::new(Page::containing_address(VirtualAddress::new(crate::USER_TMP_MISC_OFFSET)));
let mut temporary_kpage = TemporaryPage::new(Page::containing_address(VirtualAddress::new(crate::KERNEL_TMP_MISC_OFFSET)));
let mut new_utable = {
let frame = allocate_frames(1).expect("no more frames in syscall::clone new_table");
InactivePageTable::new(frame, &mut active_utable, &mut temporary_upage)
};
let mut new_ktable = {
let frame = allocate_frames(1).expect("no more frames in syscall::clone new_table");
InactivePageTable::new(frame, &mut active_ktable, &mut temporary_kpage)
};
context.arch.set_page_utable(unsafe { new_utable.address() });
context.arch.set_page_ktable(unsafe { new_ktable.address() });
// Copy kernel image mapping
{
let frame = active_ktable.p4()[crate::KERNEL_PML4].pointed_frame().expect("kernel image not mapped");
let flags = active_ktable.p4()[crate::KERNEL_PML4].flags();
active_ktable.with(&mut new_ktable, &mut temporary_kpage, |mapper| {
mapper.p4_mut()[crate::KERNEL_PML4].set(frame, flags);
});
}
// Copy kernel heap mapping
{
let frame = active_ktable.p4()[crate::KERNEL_HEAP_PML4].pointed_frame().expect("kernel heap not mapped");
let flags = active_ktable.p4()[crate::KERNEL_HEAP_PML4].flags();
active_ktable.with(&mut new_ktable, &mut temporary_kpage, |mapper| {
mapper.p4_mut()[crate::KERNEL_HEAP_PML4].set(frame, flags);
});
}
if let Some(fx) = kfx_opt.take() {
context.arch.set_fx(fx.as_ptr() as usize);
context.kfx = Some(fx);
}
// Set kernel stack
if let Some(stack) = kstack_opt.take() {
context.arch.set_stack(stack.as_ptr() as usize + offset);
context.kstack = Some(stack);
#[cfg(target_arch = "aarch64")]
{
context.arch.set_lr(interrupt::syscall::clone_ret as usize);
}
}
// TODO: Clone ksig?
// Setup image, heap, and grants
if flags.contains(CLONE_VM) {
// Copy user image mapping, if found
if ! image.is_empty() {
let frame = active_utable.p4()[crate::USER_PML4].pointed_frame().expect("user image not mapped");
let flags = active_utable.p4()[crate::USER_PML4].flags();
active_utable.with(&mut new_utable, &mut temporary_upage, |mapper| {
mapper.p4_mut()[crate::USER_PML4].set(frame, flags);
});
}
context.image = image;
// Copy grant mapping
if ! grants.read().is_empty() {
let frame = active_utable.p4()[crate::USER_GRANT_PML4].pointed_frame().expect("user grants not mapped");
let flags = active_utable.p4()[crate::USER_GRANT_PML4].flags();
active_utable.with(&mut new_utable, &mut temporary_upage, |mapper| {
mapper.p4_mut()[crate::USER_GRANT_PML4].set(frame, flags);
});
}
context.grants = grants;
} else {
// Copy percpu mapping
for cpu_id in 0..crate::cpu_count() {
extern {
// The starting byte of the thread data segment
static mut __tdata_start: u8;
// The ending byte of the thread BSS segment
static mut __tbss_end: u8;
}
let size = unsafe { & __tbss_end as *const _ as usize - & __tdata_start as *const _ as usize };
let start = crate::KERNEL_PERCPU_OFFSET + crate::KERNEL_PERCPU_SIZE * cpu_id;
let end = start + size;
let start_page = Page::containing_address(VirtualAddress::new(start));
let end_page = Page::containing_address(VirtualAddress::new(end - 1));
for page in Page::range_inclusive(start_page, end_page) {
let frame = active_ktable.translate_page(page).expect("kernel percpu not mapped");
active_ktable.with(&mut new_ktable, &mut temporary_kpage, |mapper| {
let result = mapper.map_to(page, frame, EntryFlags::PRESENT | EntryFlags::NO_EXECUTE | EntryFlags::WRITABLE);
// Ignore result due to operating on inactive table
unsafe { result.ignore(); }
});
}
}
// Move copy of image
for memory_shared in image.iter_mut() {
memory_shared.with(|memory| {
let start = VirtualAddress::new(memory.start_address().data() - crate::USER_TMP_OFFSET + crate::USER_OFFSET);
memory.move_to(start, &mut new_utable, &mut temporary_upage);
});
}
context.image = image;
// Move grants
{
let mut grants = grants.write();
let old_grants = mem::replace(&mut *grants, UserGrants::default());
for mut grant in old_grants.inner.into_iter() {
let start = VirtualAddress::new(grant.start_address().data() + crate::USER_GRANT_OFFSET - crate::USER_TMP_GRANT_OFFSET);
grant.move_to(start, &mut new_utable, &mut temporary_upage);
grants.insert(grant);
}
}
context.grants = grants;
}
// Setup user stack
if let Some(stack_shared) = stack_opt {
if flags.contains(CLONE_STACK) {
let frame = active_utable.p4()[crate::USER_STACK_PML4].pointed_frame().expect("user stack not mapped");
let flags = active_utable.p4()[crate::USER_STACK_PML4].flags();
active_utable.with(&mut new_utable, &mut temporary_upage, |mapper| {
mapper.p4_mut()[crate::USER_STACK_PML4].set(frame, flags);
});
} else {
stack_shared.with(|stack| {
stack.move_to(VirtualAddress::new(crate::USER_STACK_OFFSET), &mut new_utable, &mut temporary_upage);
});
}
context.stack = Some(stack_shared);
}
// Setup user sigstack
if let Some(mut sigstack) = sigstack_opt {
sigstack.move_to(VirtualAddress::new(crate::USER_SIGSTACK_OFFSET), &mut new_utable, &mut temporary_upage);
context.sigstack = Some(sigstack);
}
// Set up TCB
let tcb_addr = crate::USER_TCB_OFFSET + context.id.into() * PAGE_SIZE;
let mut tcb = context::memory::Memory::new(
VirtualAddress::new(tcb_addr),
PAGE_SIZE,
EntryFlags::NO_EXECUTE | EntryFlags::WRITABLE | EntryFlags::USER_ACCESSIBLE,
true
);
#[cfg(target_arch = "aarch64")]
{
if let Some(stack) = &mut context.kstack {
unsafe {
// stack_base contains a pointer to InterruptStack. Get its offset from
// stack_base itself
let istack_offset = *(stack_base as *const u64) - stack_base as u64;
// Get the top of the new process' stack
let new_sp = stack.as_mut_ptr().add(offset);
// Update the pointer to the InterruptStack to reflect the new process'
// stack. (Without this the pointer would be InterruptStack on the parent
// process' stack).
*(new_sp as *mut u64) = new_sp as u64 + istack_offset;
// Update tpidr_el0 in the new process' InterruptStack
let mut interrupt_stack = &mut *(stack.as_mut_ptr().add(offset + istack_offset as usize) as *mut crate::arch::interrupt::InterruptStack);
interrupt_stack.iret.tpidr_el0 = tcb_addr;
}
}
}
// Setup user TLS
if let Some(mut tls) = tls_opt {
// Copy TLS mapping
{
let frame = active_utable.p4()[crate::USER_TLS_PML4].pointed_frame().expect("user tls not mapped");
let flags = active_utable.p4()[crate::USER_TLS_PML4].flags();
active_utable.with(&mut new_utable, &mut temporary_upage, |mapper| {
mapper.p4_mut()[crate::USER_TLS_PML4].set(frame, flags);
});
}
// TODO: Make sure size is not greater than USER_TLS_SIZE
let tls_addr = crate::USER_TLS_OFFSET + context.id.into() * crate::USER_TLS_SIZE;
//println!("{}: Copy TLS: address 0x{:x}, size 0x{:x}", context.id.into(), tls_addr, tls.mem.size());
tls.mem.move_to(VirtualAddress::new(tls_addr), &mut new_utable, &mut temporary_upage);
unsafe {
*(tcb_addr as *mut usize) = tls.mem.start_address().data() + tls.mem.size();
}
context.tls = Some(tls);
} else {
//println!("{}: Copy TCB", context.id.into());
let parent_tcb_addr = crate::USER_TCB_OFFSET + ppid.into() * PAGE_SIZE;
unsafe {
intrinsics::copy(parent_tcb_addr as *const u8,
tcb_addr as *mut u8,
tcb.size());
}
}
tcb.move_to(VirtualAddress::new(tcb_addr), &mut new_utable, &mut temporary_upage);
context.image.push(tcb.to_shared());
context.name = name;
context.cwd = cwd;
context.files = files;
context.actions = actions;
}
}
if ptrace::send_event(ptrace_event!(PTRACE_EVENT_CLONE, pid.into())).is_some() {
// Freeze the clone, allow ptrace to put breakpoints
// to it before it starts
let contexts = context::contexts();
let context = contexts.get(pid).expect("Newly created context doesn't exist??");
let mut context = context.write();
context.ptrace_stop = true;
}
// Race to pick up the new process!
ipi(IpiKind::Switch, IpiTarget::Other);
let _ = unsafe { context::switch() };
Ok(pid)
}
fn empty(context: &mut context::Context, reaping: bool) {
if reaping {
// Memory should already be unmapped
assert!(context.image.is_empty());
assert!(context.stack.is_none());
assert!(context.sigstack.is_none());
assert!(context.tls.is_none());
} else {
// Unmap previous image, heap, grants, stack, and tls
context.image.clear();
drop(context.stack.take());
drop(context.sigstack.take());
drop(context.tls.take());
}
let mut grants = context.grants.write();
if Arc::strong_count(&context.grants) == 1 {
let grants = mem::replace(&mut *grants, UserGrants::default());
for grant in grants.inner.into_iter() {
if reaping {
println!("{}: {}: Grant should not exist: {:?}", context.id.into(), *context.name.read(), grant);
let mut new_table = unsafe { InactivePageTable::from_address(context.arch.get_page_utable()) };
let mut temporary_page = TemporaryPage::new(Page::containing_address(VirtualAddress::new(crate::USER_TMP_GRANT_OFFSET)));
grant.unmap_inactive(&mut new_table, &mut temporary_page);
} else {
grant.unmap();
}
}
}
}
struct ExecFile(FileHandle);
impl Drop for ExecFile {
fn drop(&mut self) {
let _ = syscall::close(self.0);
}
}
fn fexec_noreturn(
setuid: Option<u32>,
setgid: Option<u32>,
name: Box<str>,
data: Box<[u8]>,
args: Box<[Box<[u8]>]>,
vars: Box<[Box<[u8]>]>,
auxv: Box<[usize]>,
) -> ! {
let entry;
let singlestep;
let mut sp = crate::USER_STACK_OFFSET + crate::USER_STACK_SIZE - 256;
{
let (vfork, ppid, files) = {
let contexts = context::contexts();
let context_lock = contexts.current().ok_or(Error::new(ESRCH)).expect("exec_noreturn pid not found");
let mut context = context_lock.write();
singlestep = unsafe {
ptrace::regs_for(&context).map(|s| s.is_singlestep()).unwrap_or(false)
};
context.name = Arc::new(RwLock::new(name));
empty(&mut context, false);
if let Some(uid) = setuid {
context.euid = uid;
}
if let Some(gid) = setgid {
context.egid = gid;
}
// Map and copy new segments
let mut tls_opt = None;
{
let elf = elf::Elf::from(&data).unwrap();
entry = elf.entry();
// Always map TCB
let tcb_addr = crate::USER_TCB_OFFSET + context.id.into() * PAGE_SIZE;
let tcb_mem = context::memory::Memory::new(
VirtualAddress::new(tcb_addr),
PAGE_SIZE,
EntryFlags::NO_EXECUTE | EntryFlags::WRITABLE | EntryFlags::USER_ACCESSIBLE,
true
);
for segment in elf.segments() {
match segment.p_type {
program_header::PT_LOAD => {
let voff = segment.p_vaddr as usize % PAGE_SIZE;
let vaddr = segment.p_vaddr as usize - voff;
let mut memory = context::memory::Memory::new(
VirtualAddress::new(vaddr),
segment.p_memsz as usize + voff,
EntryFlags::NO_EXECUTE | EntryFlags::WRITABLE,
true
);
unsafe {
// Copy file data
intrinsics::copy((elf.data.as_ptr() as usize + segment.p_offset as usize) as *const u8,
segment.p_vaddr as *mut u8,
segment.p_filesz as usize);
}
let mut flags = EntryFlags::NO_EXECUTE | EntryFlags::USER_ACCESSIBLE;
if segment.p_flags & program_header::PF_R == program_header::PF_R {
flags.insert(EntryFlags::PRESENT);
}
// W ^ X. If it is executable, do not allow it to be writable, even if requested
if segment.p_flags & program_header::PF_X == program_header::PF_X {
flags.remove(EntryFlags::NO_EXECUTE);
} else if segment.p_flags & program_header::PF_W == program_header::PF_W {
flags.insert(EntryFlags::WRITABLE);
}
memory.remap(flags);
context.image.push(memory.to_shared());
},
program_header::PT_TLS => {
let aligned_size = if segment.p_align > 0 {
((segment.p_memsz + (segment.p_align - 1))/segment.p_align) * segment.p_align
} else {
segment.p_memsz
} as usize;
let rounded_size = ((aligned_size + PAGE_SIZE - 1)/PAGE_SIZE) * PAGE_SIZE;
let rounded_offset = rounded_size - aligned_size;
// TODO: Make sure size is not greater than USER_TLS_SIZE
let tls_addr = crate::USER_TLS_OFFSET + context.id.into() * crate::USER_TLS_SIZE;
let tls = context::memory::Tls {
master: VirtualAddress::new(segment.p_vaddr as usize),
file_size: segment.p_filesz as usize,
mem: context::memory::Memory::new(
VirtualAddress::new(tls_addr),
rounded_size as usize,
EntryFlags::NO_EXECUTE | EntryFlags::WRITABLE | EntryFlags::USER_ACCESSIBLE,
true
),
offset: rounded_offset as usize,
};
unsafe {
*(tcb_addr as *mut usize) = tls.mem.start_address().data() + tls.mem.size();
}
tls_opt = Some(tls);
},
_ => (),
}
}
context.image.push(tcb_mem.to_shared());
}
// Data no longer required, can deallocate
drop(data);
// Map stack
context.stack = Some(context::memory::Memory::new(
VirtualAddress::new(crate::USER_STACK_OFFSET),
crate::USER_STACK_SIZE,
EntryFlags::NO_EXECUTE | EntryFlags::WRITABLE | EntryFlags::USER_ACCESSIBLE,
true
).to_shared());
// Map stack
context.sigstack = Some(context::memory::Memory::new(
VirtualAddress::new(crate::USER_SIGSTACK_OFFSET),
crate::USER_SIGSTACK_SIZE,
EntryFlags::NO_EXECUTE | EntryFlags::WRITABLE | EntryFlags::USER_ACCESSIBLE,
true
));
// Map TLS
if let Some(mut tls) = tls_opt {
unsafe {
tls.load();
}
context.tls = Some(tls);
}
let mut push = |arg| {
sp -= mem::size_of::<usize>();
unsafe { *(sp as *mut usize) = arg; }
};
// Push auxiliary vector
push(AT_NULL);
for &arg in auxv.iter().rev() {
push(arg);
}
drop(auxv); // no longer required
let mut arg_size = 0;
// Push environment variables and arguments
for iter in &[&vars, &args] {
// Push null-terminator
push(0);
// Push pointer to content
for arg in iter.iter().rev() {
push(crate::USER_ARG_OFFSET + arg_size);
arg_size += arg.len() + 1;
}
}
// For some reason, Linux pushes the argument count here (in
// addition to being null-terminated), but not the environment
// variable count.
// TODO: Push more counts? Less? Stop having null-termination?
push(args.len());
// Write environment and argument pointers to USER_ARG_OFFSET
if arg_size > 0 {
let mut memory = context::memory::Memory::new(
VirtualAddress::new(crate::USER_ARG_OFFSET),
arg_size,
EntryFlags::NO_EXECUTE | EntryFlags::WRITABLE,
true
);
let mut arg_offset = 0;
for arg in vars.iter().rev().chain(args.iter().rev()) {
unsafe {
intrinsics::copy(arg.as_ptr(),
(crate::USER_ARG_OFFSET + arg_offset) as *mut u8,
arg.len());
}
arg_offset += arg.len();
unsafe {
*((crate::USER_ARG_OFFSET + arg_offset) as *mut u8) = 0;
}
arg_offset += 1;
}
memory.remap(EntryFlags::NO_EXECUTE | EntryFlags::USER_ACCESSIBLE);
context.image.push(memory.to_shared());
}
// Args and vars no longer required, can deallocate
drop(args);
drop(vars);
context.actions = Arc::new(RwLock::new(vec![(
SigAction {
sa_handler: unsafe { mem::transmute(SIG_DFL) },
sa_mask: [0; 2],
sa_flags: SigActionFlags::empty(),
},
0
); 128]));
let vfork = context.vfork;
context.vfork = false;
let files = Arc::clone(&context.files);
(vfork, context.ppid, files)
};
for (_fd, file_opt) in files.write().iter_mut().enumerate() {
let mut cloexec = false;
if let Some(ref file) = *file_opt {
if file.cloexec {
cloexec = true;
}
}
if cloexec {
let _ = file_opt.take().unwrap().close();
}
}
if vfork {
let contexts = context::contexts();
if let Some(context_lock) = contexts.get(ppid) {
let mut context = context_lock.write();
if ! context.unblock() {
println!("{} not blocked for exec vfork unblock", ppid.into());
}
} else {
println!("{} not found for exec vfork unblock", ppid.into());
}
}
}
// Go to usermode
unsafe { usermode(entry, sp, 0, singlestep) }
}
pub fn fexec_kernel(fd: FileHandle, args: Box<[Box<[u8]>]>, vars: Box<[Box<[u8]>]>, name_override_opt: Option<Box<str>>, auxv: Option<Vec<usize>>) -> Result<usize> {
let (uid, gid) = {
let contexts = context::contexts();
let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
let context = context_lock.read();
(context.euid, context.egid)
};
let mut stat: Stat;
let name: String;
let mut data: Vec<u8>;
{
let file = ExecFile(fd);
stat = Stat::default();
syscall::file_op_mut_slice(syscall::number::SYS_FSTAT, file.0, &mut stat)?;
let mut perm = stat.st_mode & 0o7;
if stat.st_uid == uid {
perm |= (stat.st_mode >> 6) & 0o7;
}
if stat.st_gid == gid {
perm |= (stat.st_mode >> 3) & 0o7;
}
if uid == 0 {
perm |= 0o7;
}
if perm & 0o1 != 0o1 {
return Err(Error::new(EACCES));
}
if let Some(name_override) = name_override_opt {
name = String::from(name_override);
} else {
let mut name_bytes = vec![0; 4096];
let len = syscall::file_op_mut_slice(syscall::number::SYS_FPATH, file.0, &mut name_bytes)?;
name_bytes.truncate(len);
name = match String::from_utf8(name_bytes) {
Ok(ok) => ok,
Err(_err) => {
//TODO: print error?
return Err(Error::new(EINVAL));
}
};
}
//TODO: Only read elf header, not entire file. Then read required segments
data = vec![0; stat.st_size as usize];
syscall::file_op_mut_slice(syscall::number::SYS_READ, file.0, &mut data)?;
drop(file);
}
// Set UID and GID are determined after resolving any hashbangs
let setuid = if stat.st_mode & syscall::flag::MODE_SETUID == syscall::flag::MODE_SETUID {
Some(stat.st_uid)
} else {
None
};
let setgid = if stat.st_mode & syscall::flag::MODE_SETGID == syscall::flag::MODE_SETGID {
Some(stat.st_gid)
} else {
None
};
// The argument list is limited to avoid using too much userspace stack
// This check is done last to allow all hashbangs to be resolved
//
// This should be based on the size of the userspace stack, divided
// by the cost of each argument, which should be usize * 2, with
// one additional argument added to represent the total size of the
// argument pointer array and potential padding
//
// A limit of 4095 would mean a stack of (4095 + 1) * 8 * 2 = 65536, or 64KB
if (args.len() + vars.len()) > 4095 {
return Err(Error::new(E2BIG));
}
let elf = match elf::Elf::from(&data) {
Ok(elf) => elf,
Err(err) => {
let contexts = context::contexts();
if let Some(context_lock) = contexts.current() {
let context = context_lock.read();
println!(
"{}: {}: fexec failed to execute {}: {}",
context.id.into(),
*context.name.read(),
fd.into(),
err
);
}
return Err(Error::new(ENOEXEC));
}
};
// `fexec_kernel` can recurse if an interpreter is found. We get the
// auxiliary vector from the first invocation, which is passed via an
// argument, or if this is the first one we create it.
let auxv = if let Some(auxv) = auxv {
auxv
} else {
let mut auxv = Vec::with_capacity(3);
auxv.push(AT_ENTRY);
auxv.push(elf.entry());
auxv.push(AT_PHDR);
auxv.push(elf.program_headers());
auxv
};
// We check the validity of all loadable sections here
for segment in elf.segments() {
match segment.p_type {
program_header::PT_INTERP => {
//TODO: length restraint, parse interp earlier
let mut interp = vec![0; segment.p_memsz as usize];
unsafe {
intrinsics::copy((elf.data.as_ptr() as usize + segment.p_offset as usize) as *const u8,
interp.as_mut_ptr(),
segment.p_filesz as usize);
}
let mut i = 0;
while i < interp.len() {
if interp[i] == 0 {
break;
}
i += 1;
}
interp.truncate(i);
println!(" interpreter: {:?}", ::core::str::from_utf8(&interp));
let interp_fd = super::fs::open(&interp, super::flag::O_RDONLY | super::flag::O_CLOEXEC)?;
let mut args_vec = Vec::from(args);
//TODO: pass file handle in auxv
let name_override = name.into_boxed_str();
args_vec[0] = name_override.clone().into();
// Drop variables, since fexec_kernel probably won't return
drop(elf);
drop(interp);
return fexec_kernel(
interp_fd,
args_vec.into_boxed_slice(),
vars,
Some(name_override),
Some(auxv),
);
},
program_header::PT_LOAD => {
let voff = segment.p_vaddr as usize % PAGE_SIZE;
let vaddr = segment.p_vaddr as usize - voff;
// Due to the Userspace and kernel TLS bases being located right above 2GB,
// limit any loadable sections to lower than that. Eventually we will need
// to replace this with a more intelligent TLS address
if vaddr >= 0x8000_0000 {
println!("exec: invalid section address {:X}", segment.p_vaddr);
return Err(Error::new(ENOEXEC));
}
},
_ => (),
}
}
// This is the point of no return, quite literaly. Any checks for validity need
// to be done before, and appropriate errors returned. Otherwise, we have nothing
// to return to.
fexec_noreturn(setuid, setgid, name.into_boxed_str(), data.into_boxed_slice(), args, vars, auxv.into_boxed_slice());
}
pub fn fexec(fd: FileHandle, arg_ptrs: &[[usize; 2]], var_ptrs: &[[usize; 2]]) -> Result<usize> {
let mut args = Vec::new();
for arg_ptr in arg_ptrs {
let arg = validate_slice(arg_ptr[0] as *const u8, arg_ptr[1])?;
// Argument must be moved into kernel space before exec unmaps all memory
args.push(arg.to_vec().into_boxed_slice());
}
let mut vars = Vec::new();
for var_ptr in var_ptrs {
let var = validate_slice(var_ptr[0] as *const u8, var_ptr[1])?;
// Argument must be moved into kernel space before exec unmaps all memory
vars.push(var.to_vec().into_boxed_slice());
}
// Neither arg_ptrs nor var_ptrs should be used after this point, the kernel
// now has owned copies in args and vars
fexec_kernel(fd, args.into_boxed_slice(), vars.into_boxed_slice(), None, None)
}
pub fn exit(status: usize) -> ! {
ptrace::breakpoint_callback(PTRACE_STOP_EXIT, Some(ptrace_event!(PTRACE_STOP_EXIT, status)));
{
let context_lock = {
let contexts = context::contexts();
let context_lock = contexts.current().ok_or(Error::new(ESRCH)).expect("exit failed to find context");
Arc::clone(&context_lock)
};
let mut close_files = Vec::new();
let pid = {
let mut context = context_lock.write();
{
let mut lock = context.files.write();
if Arc::strong_count(&context.files) == 1 {
mem::swap(lock.deref_mut(), &mut close_files);
}
}
context.files = Arc::new(RwLock::new(Vec::new()));
context.id
};
// Files must be closed while context is valid so that messages can be passed
for (_fd, file_opt) in close_files.drain(..).enumerate() {
if let Some(file) = file_opt {
let _ = file.close();
}
}
// PGID and PPID must be grabbed after close, as context switches could change PGID or PPID if parent exits
let (pgid, ppid) = {
let context = context_lock.read();
(context.pgid, context.ppid)
};
// Transfer child processes to parent
{
let contexts = context::contexts();
for (_id, context_lock) in contexts.iter() {
let mut context = context_lock.write();
if context.ppid == pid {
context.ppid = ppid;
context.vfork = false;
}
}
}
let (vfork, children) = {
let mut context = context_lock.write();
empty(&mut context, false);
let vfork = context.vfork;
context.vfork = false;
context.status = context::Status::Exited(status);
let children = context.waitpid.receive_all();
(vfork, children)
};
{
let contexts = context::contexts();
if let Some(parent_lock) = contexts.get(ppid) {
let waitpid = {
let mut parent = parent_lock.write();
if vfork && ! parent.unblock() {
println!("{}: {} not blocked for exit vfork unblock", pid.into(), ppid.into());
}
Arc::clone(&parent.waitpid)
};
for (c_pid, c_status) in children {
waitpid.send(c_pid, c_status);
}
waitpid.send(WaitpidKey {
pid: Some(pid),
pgid: Some(pgid)
}, (pid, status));
} else {
println!("{}: {} not found for exit vfork unblock", pid.into(), ppid.into());
}
}
// Alert any tracers waiting of this process
ptrace::close_tracee(pid);
if pid == ContextId::from(1) {
println!("Main kernel thread exited with status {:X}", status);
extern {
fn kreset() -> !;
fn kstop() -> !;
}
if status == SIGTERM {
unsafe { kreset(); }
} else {
unsafe { kstop(); }
}
}
}
let _ = unsafe { context::switch() };
unreachable!();
}
pub fn getpid() -> Result<ContextId> {
let contexts = context::contexts();
let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
let context = context_lock.read();
Ok(context.id)
}
pub fn getpgid(pid: ContextId) -> Result<ContextId> {
let contexts = context::contexts();
let context_lock = if pid.into() == 0 {
contexts.current().ok_or(Error::new(ESRCH))?
} else {
contexts.get(pid).ok_or(Error::new(ESRCH))?
};
let context = context_lock.read();
Ok(context.pgid)
}
pub fn getppid() -> Result<ContextId> {
let contexts = context::contexts();
let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
let context = context_lock.read();
Ok(context.ppid)
}
pub fn kill(pid: ContextId, sig: usize) -> Result<usize> {
let (ruid, euid, current_pgid) = {
let contexts = context::contexts();
let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
let context = context_lock.read();
(context.ruid, context.euid, context.pgid)
};
if sig < 0x7F {
let mut found = 0;
let mut sent = 0;
{
let contexts = context::contexts();
let send = |context: &mut context::Context| -> bool {
if euid == 0
|| euid == context.ruid
|| ruid == context.ruid
{
// If sig = 0, test that process exists and can be
// signalled, but don't send any signal.
if sig != 0 {
//TODO: sigprocmask
context.pending.push_back(sig as u8);
// Convert stopped processes to blocked if sending SIGCONT
if sig == SIGCONT {
if let context::Status::Stopped(_sig) = context.status {
context.status = context::Status::Blocked;
}
}
}
true
} else {
false
}
};
if pid.into() as isize > 0 {
// Send to a single process
if let Some(context_lock) = contexts.get(pid) {
let mut context = context_lock.write();
found += 1;
if send(&mut context) {
sent += 1;
}
}
} else if pid.into() as isize == -1 {
// Send to every process with permission, except for init
for (_id, context_lock) in contexts.iter() {
let mut context = context_lock.write();
if context.id.into() > 2 {
found += 1;
if send(&mut context) {
sent += 1;
}
}
}
} else {
let pgid = if pid.into() == 0 {
current_pgid
} else {
ContextId::from(-(pid.into() as isize) as usize)
};
// Send to every process in the process group whose ID
for (_id, context_lock) in contexts.iter() {
let mut context = context_lock.write();
if context.pgid == pgid {
found += 1;
if send(&mut context) {
sent += 1;
}
}
}
}
}
if found == 0 {
Err(Error::new(ESRCH))
} else if sent == 0 {
Err(Error::new(EPERM))
} else {
// Switch to ensure delivery to self
unsafe { context::switch(); }
Ok(0)
}
} else {
Err(Error::new(EINVAL))
}
}
pub fn mprotect(address: usize, size: usize, flags: MapFlags) -> Result<usize> {
// println!("mprotect {:#X}, {}, {:#X}", address, size, flags);
let end_offset = size.checked_sub(1).ok_or(Error::new(EFAULT))?;
let end_address = address.checked_add(end_offset).ok_or(Error::new(EFAULT))?;
let mut active_table = unsafe { ActivePageTable::new(PageTableType::User) };
let mut flush_all = MapperFlushAll::new();
let start_page = Page::containing_address(VirtualAddress::new(address));
let end_page = Page::containing_address(VirtualAddress::new(end_address));
for page in Page::range_inclusive(start_page, end_page) {
// Check if the page is actually mapped before trying to change the flags.
// FIXME can other processes change if a page is mapped beneath our feet?
let mut page_flags = if let Some(page_flags) = active_table.translate_page_flags(page) {
page_flags
} else {
flush_all.flush(&mut active_table);
return Err(Error::new(EFAULT));
};
if !page_flags.contains(EntryFlags::PRESENT) {
flush_all.flush(&mut active_table);
return Err(Error::new(EFAULT));
}
if flags.contains(PROT_EXEC) {
page_flags.remove(EntryFlags::NO_EXECUTE);
} else {
page_flags.insert(EntryFlags::NO_EXECUTE);
}
if flags.contains(PROT_WRITE) {
//TODO: Not allowing gain of write privileges
} else {
page_flags.remove(EntryFlags::WRITABLE);
}
if flags.contains(PROT_READ) {
//TODO: No flags for readable pages
} else {
//TODO: No flags for readable pages
}
let flush = active_table.remap(page, page_flags);
flush_all.consume(flush);
}
flush_all.flush(&mut active_table);
Ok(0)
}
pub fn setpgid(pid: ContextId, pgid: ContextId) -> Result<usize> {
let contexts = context::contexts();
let current_pid = {
let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
let context = context_lock.read();
context.id
};
let context_lock = if pid.into() == 0 {
contexts.current().ok_or(Error::new(ESRCH))?
} else {
contexts.get(pid).ok_or(Error::new(ESRCH))?
};
let mut context = context_lock.write();
if context.id == current_pid || context.ppid == current_pid {
if pgid.into() == 0 {
context.pgid = context.id;
} else {
context.pgid = pgid;
}
Ok(0)
} else {
Err(Error::new(ESRCH))
}
}
pub fn sigaction(sig: usize, act_opt: Option<&SigAction>, oldact_opt: Option<&mut SigAction>, restorer: usize) -> Result<usize> {
if sig > 0 && sig <= 0x7F {
let contexts = context::contexts();
let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
let context = context_lock.read();
let mut actions = context.actions.write();
if let Some(oldact) = oldact_opt {
*oldact = actions[sig].0;
}
if let Some(act) = act_opt {
actions[sig] = (*act, restorer);
}
Ok(0)
} else {
Err(Error::new(EINVAL))
}
}
pub fn sigprocmask(how: usize, mask_opt: Option<&[u64; 2]>, oldmask_opt: Option<&mut [u64; 2]>) -> Result<usize> {
{
let contexts = context::contexts();
let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
let mut context = context_lock.write();
if let Some(oldmask) = oldmask_opt {
*oldmask = context.sigmask;
}
if let Some(mask) = mask_opt {
match how {
SIG_BLOCK => {
context.sigmask[0] |= mask[0];
context.sigmask[1] |= mask[1];
},
SIG_UNBLOCK => {
context.sigmask[0] &= !mask[0];
context.sigmask[1] &= !mask[1];
},
SIG_SETMASK => {
context.sigmask[0] = mask[0];
context.sigmask[1] = mask[1];
},
_ => {
return Err(Error::new(EINVAL));
}
}
}
}
Ok(0)
}
pub fn sigreturn() -> Result<usize> {
{
let contexts = context::contexts();
let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
let mut context = context_lock.write();
context.ksig_restore = true;
context.block("sigreturn");
}
let _ = unsafe { context::switch() };
unreachable!();
}
pub fn umask(mask: usize) -> Result<usize> {
let previous;
{
let contexts = context::contexts();
let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
let mut context = context_lock.write();
previous = context.umask;
context.umask = mask;
}
Ok(previous)
}
fn reap(pid: ContextId) -> Result<ContextId> {
// Spin until not running
let mut running = true;
while running {
{
let contexts = context::contexts();
let context_lock = contexts.get(pid).ok_or(Error::new(ESRCH))?;
let context = context_lock.read();
running = context.running;
}
interrupt::pause();
}
let mut contexts = context::contexts_mut();
let context_lock = contexts.remove(pid).ok_or(Error::new(ESRCH))?;
{
let mut context = context_lock.write();
empty(&mut context, true);
}
drop(context_lock);
Ok(pid)
}
pub fn waitpid(pid: ContextId, status_ptr: usize, flags: WaitFlags) -> Result<ContextId> {
let (ppid, waitpid) = {
let contexts = context::contexts();
let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
let context = context_lock.read();
(context.id, Arc::clone(&context.waitpid))
};
let mut tmp = [0];
let status_slice = if status_ptr != 0 {
validate_slice_mut(status_ptr as *mut usize, 1)?
} else {
&mut tmp
};
let mut grim_reaper = |w_pid: ContextId, status: usize| -> Option<Result<ContextId>> {
if wifcontinued(status) {
if flags & WCONTINUED == WCONTINUED {
status_slice[0] = status;
Some(Ok(w_pid))
} else {
None
}
} else if wifstopped(status) {
if flags & WUNTRACED == WUNTRACED {
status_slice[0] = status;
Some(Ok(w_pid))
} else {
None
}
} else {
status_slice[0] = status;
Some(reap(w_pid))
}
};
loop {
let res_opt = if pid.into() == 0 {
// Check for existence of child
{
let mut found = false;
let contexts = context::contexts();
for (_id, context_lock) in contexts.iter() {
let context = context_lock.read();
if context.ppid == ppid {
found = true;
break;
}
}
if ! found {
return Err(Error::new(ECHILD));
}
}
if flags & WNOHANG == WNOHANG {
if let Some((_wid, (w_pid, status))) = waitpid.receive_any_nonblock() {
grim_reaper(w_pid, status)
} else {
Some(Ok(ContextId::from(0)))
}
} else {
let (_wid, (w_pid, status)) = waitpid.receive_any("waitpid any");
grim_reaper(w_pid, status)
}
} else if (pid.into() as isize) < 0 {
let pgid = ContextId::from(-(pid.into() as isize) as usize);
// Check for existence of child in process group PGID
{
let mut found = false;
let contexts = context::contexts();
for (_id, context_lock) in contexts.iter() {
let context = context_lock.read();
if context.pgid == pgid {
found = true;
break;
}
}
if ! found {
return Err(Error::new(ECHILD));
}
}
if flags & WNOHANG == WNOHANG {
if let Some((w_pid, status)) = waitpid.receive_nonblock(&WaitpidKey {
pid: None,
pgid: Some(pgid)
}) {
grim_reaper(w_pid, status)
} else {
Some(Ok(ContextId::from(0)))
}
} else {
let (w_pid, status) = waitpid.receive(&WaitpidKey {
pid: None,
pgid: Some(pgid)
}, "waitpid pgid");
grim_reaper(w_pid, status)
}
} else {
let hack_status = {
let contexts = context::contexts();
let context_lock = contexts.get(pid).ok_or(Error::new(ECHILD))?;
let mut context = context_lock.write();
if context.ppid != ppid {
println!("TODO: Hack for rustc - changing ppid of {} from {} to {}", context.id.into(), context.ppid.into(), ppid.into());
context.ppid = ppid;
//return Err(Error::new(ECHILD));
Some(context.status)
} else {
None
}
};
if let Some(context::Status::Exited(status)) = hack_status {
let _ = waitpid.receive_nonblock(&WaitpidKey {
pid: Some(pid),
pgid: None
});
grim_reaper(pid, status)
} else if flags & WNOHANG == WNOHANG {
if let Some((w_pid, status)) = waitpid.receive_nonblock(&WaitpidKey {
pid: Some(pid),
pgid: None
}) {
grim_reaper(w_pid, status)
} else {
Some(Ok(ContextId::from(0)))
}
} else {
let (w_pid, status) = waitpid.receive(&WaitpidKey {
pid: Some(pid),
pgid: None
}, "waitpid pid");
grim_reaper(w_pid, status)
}
};
if let Some(res) = res_opt {
return res;
}
}
}