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Process.cpp
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Process.cpp
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/*
* Copyright (c) 2018-2020, Andreas Kling <[email protected]>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/Demangle.h>
#include <AK/FileSystemPath.h>
#include <AK/ScopeGuard.h>
#include <AK/StdLibExtras.h>
#include <AK/StringBuilder.h>
#include <AK/Time.h>
#include <AK/Types.h>
#include <Kernel/Arch/i386/CPU.h>
#include <Kernel/Devices/BlockDevice.h>
#include <Kernel/Devices/KeyboardDevice.h>
#include <Kernel/Devices/NullDevice.h>
#include <Kernel/Devices/PCSpeaker.h>
#include <Kernel/Devices/PIT.h>
#include <Kernel/Devices/RandomDevice.h>
#include <Kernel/FileSystem/Custody.h>
#include <Kernel/FileSystem/DevPtsFS.h>
#include <Kernel/FileSystem/Ext2FileSystem.h>
#include <Kernel/FileSystem/FIFO.h>
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/FileSystem/InodeWatcher.h>
#include <Kernel/FileSystem/ProcFS.h>
#include <Kernel/FileSystem/TmpFS.h>
#include <Kernel/FileSystem/VirtualFileSystem.h>
#include <Kernel/Heap/kmalloc.h>
#include <Kernel/KBufferBuilder.h>
#include <Kernel/KSyms.h>
#include <Kernel/KernelInfoPage.h>
#include <Kernel/Module.h>
#include <Kernel/Multiboot.h>
#include <Kernel/Net/Socket.h>
#include <Kernel/PerformanceEventBuffer.h>
#include <Kernel/Process.h>
#include <Kernel/ProcessTracer.h>
#include <Kernel/Profiling.h>
#include <Kernel/RTC.h>
#include <Kernel/Random.h>
#include <Kernel/Scheduler.h>
#include <Kernel/SharedBuffer.h>
#include <Kernel/Syscall.h>
#include <Kernel/TTY/MasterPTY.h>
#include <Kernel/TTY/TTY.h>
#include <Kernel/Thread.h>
#include <Kernel/VM/InodeVMObject.h>
#include <Kernel/VM/PageDirectory.h>
#include <Kernel/VM/PurgeableVMObject.h>
#include <LibBareMetal/IO.h>
#include <LibBareMetal/Output/Console.h>
#include <LibBareMetal/StdLib.h>
#include <LibC/errno_numbers.h>
#include <LibC/limits.h>
#include <LibC/signal_numbers.h>
#include <LibELF/ELFLoader.h>
//#define PROCESS_DEBUG
//#define DEBUG_POLL_SELECT
//#define DEBUG_IO
//#define TASK_DEBUG
//#define FORK_DEBUG
//#define EXEC_DEBUG
//#define SIGNAL_DEBUG
//#define SHARED_BUFFER_DEBUG
namespace Kernel {
static void create_signal_trampolines();
static void create_kernel_info_page();
Process* Process::current;
static pid_t next_pid;
InlineLinkedList<Process>* g_processes;
static String* s_hostname;
static Lock* s_hostname_lock;
static VirtualAddress s_info_page_address_for_userspace;
static VirtualAddress s_info_page_address_for_kernel;
VirtualAddress g_return_to_ring3_from_signal_trampoline;
HashMap<String, OwnPtr<Module>>* g_modules;
pid_t Process::allocate_pid()
{
InterruptDisabler disabler;
return next_pid++;
}
void Process::initialize()
{
g_modules = new HashMap<String, OwnPtr<Module>>;
next_pid = 0;
g_processes = new InlineLinkedList<Process>;
s_hostname = new String("courage");
s_hostname_lock = new Lock;
create_signal_trampolines();
create_kernel_info_page();
}
void Process::update_info_page_timestamp(const timeval& tv)
{
auto* info_page = (KernelInfoPage*)s_info_page_address_for_kernel.as_ptr();
info_page->serial++;
const_cast<timeval&>(info_page->now) = tv;
}
Vector<pid_t> Process::all_pids()
{
Vector<pid_t> pids;
InterruptDisabler disabler;
pids.ensure_capacity((int)g_processes->size_slow());
for (auto& process : *g_processes)
pids.append(process.pid());
return pids;
}
Vector<Process*> Process::all_processes()
{
Vector<Process*> processes;
InterruptDisabler disabler;
processes.ensure_capacity((int)g_processes->size_slow());
for (auto& process : *g_processes)
processes.append(&process);
return processes;
}
bool Process::in_group(gid_t gid) const
{
return m_gid == gid || m_extra_gids.contains(gid);
}
Range Process::allocate_range(VirtualAddress vaddr, size_t size, size_t alignment)
{
vaddr.mask(PAGE_MASK);
size = PAGE_ROUND_UP(size);
if (vaddr.is_null())
return page_directory().range_allocator().allocate_anywhere(size, alignment);
return page_directory().range_allocator().allocate_specific(vaddr, size);
}
static unsigned prot_to_region_access_flags(int prot)
{
unsigned access = 0;
if (prot & PROT_READ)
access |= Region::Access::Read;
if (prot & PROT_WRITE)
access |= Region::Access::Write;
if (prot & PROT_EXEC)
access |= Region::Access::Execute;
return access;
}
Region& Process::allocate_split_region(const Region& source_region, const Range& range, size_t offset_in_vmobject)
{
auto& region = add_region(Region::create_user_accessible(range, source_region.vmobject(), offset_in_vmobject, source_region.name(), source_region.access()));
region.set_mmap(source_region.is_mmap());
region.set_stack(source_region.is_stack());
size_t page_offset_in_source_region = (offset_in_vmobject - source_region.offset_in_vmobject()) / PAGE_SIZE;
for (size_t i = 0; i < region.page_count(); ++i) {
if (source_region.should_cow(page_offset_in_source_region + i))
region.set_should_cow(i, true);
}
return region;
}
Region* Process::allocate_region(const Range& range, const String& name, int prot, bool commit)
{
ASSERT(range.is_valid());
auto& region = add_region(Region::create_user_accessible(range, name, prot_to_region_access_flags(prot)));
region.map(page_directory());
if (commit)
region.commit();
return ®ion;
}
Region* Process::allocate_region(VirtualAddress vaddr, size_t size, const String& name, int prot, bool commit)
{
auto range = allocate_range(vaddr, size);
if (!range.is_valid())
return nullptr;
return allocate_region(range, name, prot, commit);
}
Region* Process::allocate_file_backed_region(VirtualAddress vaddr, size_t size, NonnullRefPtr<Inode> inode, const String& name, int prot)
{
auto range = allocate_range(vaddr, size);
if (!range.is_valid())
return nullptr;
auto& region = add_region(Region::create_user_accessible(range, inode, name, prot_to_region_access_flags(prot)));
region.map(page_directory());
return ®ion;
}
Region* Process::allocate_region_with_vmobject(const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const String& name, int prot, bool user_accessible)
{
ASSERT(range.is_valid());
size_t end_in_vmobject = offset_in_vmobject + range.size();
if (end_in_vmobject <= offset_in_vmobject) {
dbg() << "allocate_region_with_vmobject: Overflow (offset + size)";
return nullptr;
}
if (offset_in_vmobject >= vmobject->size()) {
dbg() << "allocate_region_with_vmobject: Attempt to allocate a region with an offset past the end of its VMObject.";
return nullptr;
}
if (end_in_vmobject > vmobject->size()) {
dbg() << "allocate_region_with_vmobject: Attempt to allocate a region with an end past the end of its VMObject.";
return nullptr;
}
offset_in_vmobject &= PAGE_MASK;
Region* region;
if (user_accessible)
region = &add_region(Region::create_user_accessible(range, move(vmobject), offset_in_vmobject, name, prot_to_region_access_flags(prot)));
else
region = &add_region(Region::create_kernel_only(range, move(vmobject), offset_in_vmobject, name, prot_to_region_access_flags(prot)));
region->map(page_directory());
return region;
}
Region* Process::allocate_region_with_vmobject(VirtualAddress vaddr, size_t size, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const String& name, int prot, bool user_accessible)
{
auto range = allocate_range(vaddr, size);
if (!range.is_valid())
return nullptr;
return allocate_region_with_vmobject(range, move(vmobject), offset_in_vmobject, name, prot, user_accessible);
}
bool Process::deallocate_region(Region& region)
{
InterruptDisabler disabler;
if (m_region_lookup_cache.region == ®ion)
m_region_lookup_cache.region = nullptr;
for (size_t i = 0; i < m_regions.size(); ++i) {
if (&m_regions[i] == ®ion) {
m_regions.unstable_remove(i);
return true;
}
}
return false;
}
Region* Process::region_from_range(const Range& range)
{
if (m_region_lookup_cache.range == range && m_region_lookup_cache.region)
return m_region_lookup_cache.region;
size_t size = PAGE_ROUND_UP(range.size());
for (auto& region : m_regions) {
if (region.vaddr() == range.base() && region.size() == size) {
m_region_lookup_cache.range = range;
m_region_lookup_cache.region = region.make_weak_ptr();
return ®ion;
}
}
return nullptr;
}
Region* Process::region_containing(const Range& range)
{
for (auto& region : m_regions) {
if (region.contains(range))
return ®ion;
}
return nullptr;
}
int Process::sys$set_mmap_name(const Syscall::SC_set_mmap_name_params* user_params)
{
REQUIRE_PROMISE(stdio);
Syscall::SC_set_mmap_name_params params;
if (!validate_read_and_copy_typed(¶ms, user_params))
return -EFAULT;
if (params.name.length > PATH_MAX)
return -ENAMETOOLONG;
auto name = validate_and_copy_string_from_user(params.name);
if (name.is_null())
return -EFAULT;
auto* region = region_from_range({ VirtualAddress(params.addr), params.size });
if (!region)
return -EINVAL;
if (!region->is_mmap())
return -EPERM;
region->set_name(name);
return 0;
}
static bool validate_mmap_prot(int prot, bool map_stack)
{
bool readable = prot & PROT_READ;
bool writable = prot & PROT_WRITE;
bool executable = prot & PROT_EXEC;
if (writable && executable)
return false;
if (map_stack) {
if (executable)
return false;
if (!readable || !writable)
return false;
}
return true;
}
static bool validate_inode_mmap_prot(const Process& process, int prot, const Inode& inode)
{
auto metadata = inode.metadata();
if ((prot & PROT_WRITE) && !metadata.may_write(process))
return false;
if ((prot & PROT_READ) && !metadata.may_read(process))
return false;
InterruptDisabler disabler;
if (inode.vmobject()) {
if ((prot & PROT_EXEC) && inode.vmobject()->writable_mappings())
return false;
if ((prot & PROT_WRITE) && inode.vmobject()->executable_mappings())
return false;
}
return true;
}
// Carve out a virtual address range from a region and return the two regions on either side
Vector<Region*, 2> Process::split_region_around_range(const Region& source_region, const Range& desired_range)
{
Range old_region_range = source_region.range();
auto remaining_ranges_after_unmap = old_region_range.carve(desired_range);
ASSERT(!remaining_ranges_after_unmap.is_empty());
auto make_replacement_region = [&](const Range& new_range) -> Region& {
ASSERT(new_range.base() >= old_region_range.base());
ASSERT(new_range.end() <= old_region_range.end());
size_t new_range_offset_in_vmobject = source_region.offset_in_vmobject() + (new_range.base().get() - old_region_range.base().get());
return allocate_split_region(source_region, new_range, new_range_offset_in_vmobject);
};
Vector<Region*, 2> new_regions;
for (auto& new_range : remaining_ranges_after_unmap) {
new_regions.unchecked_append(&make_replacement_region(new_range));
}
return new_regions;
}
void* Process::sys$mmap(const Syscall::SC_mmap_params* user_params)
{
REQUIRE_PROMISE(stdio);
Syscall::SC_mmap_params params;
if (!validate_read_and_copy_typed(¶ms, user_params))
return (void*)-EFAULT;
void* addr = (void*)params.addr;
size_t size = params.size;
size_t alignment = params.alignment;
int prot = params.prot;
int flags = params.flags;
int fd = params.fd;
int offset = params.offset;
if (alignment & ~PAGE_MASK)
return (void*)-EINVAL;
if (!is_user_range(VirtualAddress(addr), size))
return (void*)-EFAULT;
String name;
if (params.name.characters) {
if (params.name.length > PATH_MAX)
return (void*)-ENAMETOOLONG;
name = validate_and_copy_string_from_user(params.name);
if (name.is_null())
return (void*)-EFAULT;
}
if (size == 0)
return (void*)-EINVAL;
if ((uintptr_t)addr & ~PAGE_MASK)
return (void*)-EINVAL;
bool map_shared = flags & MAP_SHARED;
bool map_anonymous = flags & MAP_ANONYMOUS;
bool map_purgeable = flags & MAP_PURGEABLE;
bool map_private = flags & MAP_PRIVATE;
bool map_stack = flags & MAP_STACK;
bool map_fixed = flags & MAP_FIXED;
if (map_shared && map_private)
return (void*)-EINVAL;
if (!map_shared && !map_private)
return (void*)-EINVAL;
if (!validate_mmap_prot(prot, map_stack))
return (void*)-EINVAL;
if (map_stack && (!map_private || !map_anonymous))
return (void*)-EINVAL;
Region* region = nullptr;
auto range = allocate_range(VirtualAddress(addr), size, alignment);
if (!range.is_valid())
return (void*)-ENOMEM;
if (map_purgeable) {
auto vmobject = PurgeableVMObject::create_with_size(size);
region = allocate_region_with_vmobject(range, vmobject, 0, !name.is_null() ? name : "mmap (purgeable)", prot);
if (!region && (!map_fixed && addr != 0))
region = allocate_region_with_vmobject({}, size, vmobject, 0, !name.is_null() ? name : "mmap (purgeable)", prot);
} else if (map_anonymous) {
region = allocate_region(range, !name.is_null() ? name : "mmap", prot, false);
if (!region && (!map_fixed && addr != 0))
region = allocate_region(allocate_range({}, size), !name.is_null() ? name : "mmap", prot, false);
} else {
if (offset < 0)
return (void*)-EINVAL;
if (static_cast<size_t>(offset) & ~PAGE_MASK)
return (void*)-EINVAL;
// FIXME: Implement MAP_PRIVATE for FileDescription-backed mmap
if (map_private)
return (void*)-ENOTSUP;
auto description = file_description(fd);
if (!description)
return (void*)-EBADF;
if (description->is_directory())
return (void*)-ENODEV;
if ((prot & PROT_READ) && !description->is_readable())
return (void*)-EACCES;
if ((prot & PROT_WRITE) && !description->is_writable())
return (void*)-EACCES;
if (description->inode()) {
if (!validate_inode_mmap_prot(*this, prot, *description->inode()))
return (void*)-EACCES;
}
auto region_or_error = description->mmap(*this, VirtualAddress(addr), static_cast<size_t>(offset), size, prot);
if (region_or_error.is_error()) {
// Fail if MAP_FIXED or address is 0, retry otherwise
if (map_fixed || addr == 0)
return (void*)(int)region_or_error.error();
region_or_error = description->mmap(*this, {}, static_cast<size_t>(offset), size, prot);
}
if (region_or_error.is_error())
return (void*)(int)region_or_error.error();
region = region_or_error.value();
}
if (!region)
return (void*)-ENOMEM;
region->set_mmap(true);
if (map_shared)
region->set_shared(true);
if (map_stack)
region->set_stack(true);
if (!name.is_null())
region->set_name(name);
return region->vaddr().as_ptr();
}
int Process::sys$munmap(void* addr, size_t size)
{
REQUIRE_PROMISE(stdio);
if (!size)
return -EINVAL;
if (!is_user_range(VirtualAddress(addr), size))
return -EFAULT;
Range range_to_unmap { VirtualAddress(addr), size };
if (auto* whole_region = region_from_range(range_to_unmap)) {
if (!whole_region->is_mmap())
return -EPERM;
bool success = deallocate_region(*whole_region);
ASSERT(success);
return 0;
}
if (auto* old_region = region_containing(range_to_unmap)) {
if (!old_region->is_mmap())
return -EPERM;
auto new_regions = split_region_around_range(*old_region, range_to_unmap);
// We manually unmap the old region here, specifying that we *don't* want the VM deallocated.
old_region->unmap(Region::ShouldDeallocateVirtualMemoryRange::No);
deallocate_region(*old_region);
// Instead we give back the unwanted VM manually.
page_directory().range_allocator().deallocate(range_to_unmap);
// And finally we map the new region(s) using our page directory (they were just allocated and don't have one).
for (auto* new_region : new_regions) {
new_region->map(page_directory());
}
return 0;
}
// FIXME: We should also support munmap() across multiple regions. (#175)
return -EINVAL;
}
int Process::sys$mprotect(void* addr, size_t size, int prot)
{
REQUIRE_PROMISE(stdio);
if (!size)
return -EINVAL;
if (!is_user_range(VirtualAddress(addr), size))
return -EFAULT;
Range range_to_mprotect = { VirtualAddress(addr), size };
if (auto* whole_region = region_from_range(range_to_mprotect)) {
if (!whole_region->is_mmap())
return -EPERM;
if (!validate_mmap_prot(prot, whole_region->is_stack()))
return -EINVAL;
if (whole_region->access() == prot_to_region_access_flags(prot))
return 0;
if (whole_region->vmobject().is_inode()
&& !validate_inode_mmap_prot(*this, prot, static_cast<const InodeVMObject&>(whole_region->vmobject()).inode())) {
return -EACCES;
}
whole_region->set_readable(prot & PROT_READ);
whole_region->set_writable(prot & PROT_WRITE);
whole_region->set_executable(prot & PROT_EXEC);
whole_region->remap();
return 0;
}
// Check if we can carve out the desired range from an existing region
if (auto* old_region = region_containing(range_to_mprotect)) {
if (!old_region->is_mmap())
return -EPERM;
if (!validate_mmap_prot(prot, old_region->is_stack()))
return -EINVAL;
if (old_region->access() == prot_to_region_access_flags(prot))
return 0;
if (old_region->vmobject().is_inode()
&& !validate_inode_mmap_prot(*this, prot, static_cast<const InodeVMObject&>(old_region->vmobject()).inode())) {
return -EACCES;
}
// This vector is the region(s) adjacent to our range.
// We need to allocate a new region for the range we wanted to change permission bits on.
auto adjacent_regions = split_region_around_range(*old_region, range_to_mprotect);
size_t new_range_offset_in_vmobject = old_region->offset_in_vmobject() + (range_to_mprotect.base().get() - old_region->range().base().get());
auto& new_region = allocate_split_region(*old_region, range_to_mprotect, new_range_offset_in_vmobject);
new_region.set_readable(prot & PROT_READ);
new_region.set_writable(prot & PROT_WRITE);
new_region.set_executable(prot & PROT_EXEC);
// Unmap the old region here, specifying that we *don't* want the VM deallocated.
old_region->unmap(Region::ShouldDeallocateVirtualMemoryRange::No);
deallocate_region(*old_region);
// Map the new regions using our page directory (they were just allocated and don't have one).
for (auto* adjacent_region : adjacent_regions) {
adjacent_region->map(page_directory());
}
new_region.map(page_directory());
return 0;
}
// FIXME: We should also support mprotect() across multiple regions. (#175) (#964)
return -EINVAL;
}
int Process::sys$madvise(void* address, size_t size, int advice)
{
REQUIRE_PROMISE(stdio);
if (!size)
return -EINVAL;
if (!is_user_range(VirtualAddress(address), size))
return -EFAULT;
auto* region = region_from_range({ VirtualAddress(address), size });
if (!region)
return -EINVAL;
if (!region->is_mmap())
return -EPERM;
if ((advice & MADV_SET_VOLATILE) && (advice & MADV_SET_NONVOLATILE))
return -EINVAL;
if (advice & MADV_SET_VOLATILE) {
if (!region->vmobject().is_purgeable())
return -EPERM;
auto& vmobject = static_cast<PurgeableVMObject&>(region->vmobject());
vmobject.set_volatile(true);
return 0;
}
if (advice & MADV_SET_NONVOLATILE) {
if (!region->vmobject().is_purgeable())
return -EPERM;
auto& vmobject = static_cast<PurgeableVMObject&>(region->vmobject());
if (!vmobject.is_volatile())
return 0;
vmobject.set_volatile(false);
bool was_purged = vmobject.was_purged();
vmobject.set_was_purged(false);
return was_purged ? 1 : 0;
}
if (advice & MADV_GET_VOLATILE) {
if (!region->vmobject().is_purgeable())
return -EPERM;
auto& vmobject = static_cast<PurgeableVMObject&>(region->vmobject());
return vmobject.is_volatile() ? 0 : 1;
}
return -EINVAL;
}
int Process::sys$purge(int mode)
{
REQUIRE_NO_PROMISES;
if (!is_superuser())
return -EPERM;
int purged_page_count = 0;
if (mode & PURGE_ALL_VOLATILE) {
NonnullRefPtrVector<PurgeableVMObject> vmobjects;
{
InterruptDisabler disabler;
MM.for_each_vmobject([&](auto& vmobject) {
if (vmobject.is_purgeable())
vmobjects.append(static_cast<PurgeableVMObject&>(vmobject));
return IterationDecision::Continue;
});
}
for (auto& vmobject : vmobjects) {
purged_page_count += vmobject.purge();
}
}
if (mode & PURGE_ALL_CLEAN_INODE) {
NonnullRefPtrVector<InodeVMObject> vmobjects;
{
InterruptDisabler disabler;
MM.for_each_vmobject([&](auto& vmobject) {
if (vmobject.is_inode())
vmobjects.append(static_cast<InodeVMObject&>(vmobject));
return IterationDecision::Continue;
});
}
for (auto& vmobject : vmobjects) {
purged_page_count += vmobject.release_all_clean_pages();
}
}
return purged_page_count;
}
int Process::sys$gethostname(char* buffer, ssize_t size)
{
REQUIRE_PROMISE(stdio);
if (size < 0)
return -EINVAL;
if (!validate_write(buffer, size))
return -EFAULT;
LOCKER(*s_hostname_lock);
if ((size_t)size < (s_hostname->length() + 1))
return -ENAMETOOLONG;
copy_to_user(buffer, s_hostname->characters(), s_hostname->length() + 1);
return 0;
}
pid_t Process::sys$fork(RegisterState& regs)
{
REQUIRE_PROMISE(proc);
Thread* child_first_thread = nullptr;
auto* child = new Process(child_first_thread, m_name, m_uid, m_gid, m_pid, m_ring, m_cwd, m_executable, m_tty, this);
child->m_root_directory = m_root_directory;
child->m_root_directory_relative_to_global_root = m_root_directory_relative_to_global_root;
child->m_promises = m_promises;
child->m_execpromises = m_execpromises;
child->m_veil_state = m_veil_state;
child->m_unveiled_paths = m_unveiled_paths;
child->m_fds = m_fds;
child->m_sid = m_sid;
child->m_pgid = m_pgid;
child->m_umask = m_umask;
#ifdef FORK_DEBUG
dbg() << "fork: child=" << child;
#endif
for (auto& region : m_regions) {
#ifdef FORK_DEBUG
dbg() << "fork: cloning Region{" << ®ion << "} '" << region.name() << "' @ " << region.vaddr();
#endif
auto& child_region = child->add_region(region.clone());
child_region.map(child->page_directory());
if (®ion == m_master_tls_region)
child->m_master_tls_region = &child_region;
}
child->m_extra_gids = m_extra_gids;
auto& child_tss = child_first_thread->m_tss;
child_tss.eax = 0; // fork() returns 0 in the child :^)
child_tss.ebx = regs.ebx;
child_tss.ecx = regs.ecx;
child_tss.edx = regs.edx;
child_tss.ebp = regs.ebp;
child_tss.esp = regs.userspace_esp;
child_tss.esi = regs.esi;
child_tss.edi = regs.edi;
child_tss.eflags = regs.eflags;
child_tss.eip = regs.eip;
child_tss.cs = regs.cs;
child_tss.ds = regs.ds;
child_tss.es = regs.es;
child_tss.fs = regs.fs;
child_tss.gs = regs.gs;
child_tss.ss = regs.userspace_ss;
#ifdef FORK_DEBUG
dbg() << "fork: child will begin executing at " << String::format("%w", child_tss.cs) << ":" << String::format("%x", child_tss.eip) << " with stack " << String::format("%w", child_tss.ss) << ":" << String::format("%x", child_tss.esp) << ", kstack " << String::format("%w", child_tss.ss0) << ":" << String::format("%x", child_tss.esp0);
#endif
{
InterruptDisabler disabler;
g_processes->prepend(child);
}
#ifdef TASK_DEBUG
kprintf("Process %u (%s) forked from %u @ %p\n", child->pid(), child->name().characters(), m_pid, child_tss.eip);
#endif
child_first_thread->set_state(Thread::State::Skip1SchedulerPass);
return child->pid();
}
void Process::kill_threads_except_self()
{
InterruptDisabler disabler;
if (m_thread_count <= 1)
return;
for_each_thread([&](Thread& thread) {
if (&thread == Thread::current
|| thread.state() == Thread::State::Dead
|| thread.state() == Thread::State::Dying)
return IterationDecision::Continue;
// At this point, we have no joiner anymore
thread.m_joiner = nullptr;
thread.set_should_die();
if (thread.state() != Thread::State::Dead)
thread.set_state(Thread::State::Dying);
return IterationDecision::Continue;
});
big_lock().clear_waiters();
}
void Process::kill_all_threads()
{
for_each_thread([&](Thread& thread) {
thread.set_should_die();
return IterationDecision::Continue;
});
}
int Process::do_exec(NonnullRefPtr<FileDescription> main_program_description, Vector<String> arguments, Vector<String> environment, RefPtr<FileDescription> interpreter_description)
{
ASSERT(is_ring3());
auto path = main_program_description->absolute_path();
dbg() << "do_exec(" << path << ")";
size_t total_blob_size = 0;
for (auto& a : arguments)
total_blob_size += a.length() + 1;
for (auto& e : environment)
total_blob_size += e.length() + 1;
size_t total_meta_size = sizeof(char*) * (arguments.size() + 1) + sizeof(char*) * (environment.size() + 1);
// FIXME: How much stack space does process startup need?
if ((total_blob_size + total_meta_size) >= Thread::default_userspace_stack_size)
return -E2BIG;
auto parts = path.split('/');
if (parts.is_empty())
return -ENOENT;
RefPtr<InodeVMObject> vmobject;
if (interpreter_description) {
vmobject = InodeVMObject::create_with_inode(*interpreter_description->inode());
} else {
vmobject = InodeVMObject::create_with_inode(*main_program_description->inode());
}
if (static_cast<const InodeVMObject&>(*vmobject).writable_mappings()) {
dbg() << "Refusing to execute a write-mapped program";
return -ETXTBSY;
}
// Disable profiling temporarily in case it's running on this process.
bool was_profiling = is_profiling();
TemporaryChange profiling_disabler(m_profiling, false);
// Mark this thread as the current thread that does exec
// No other thread from this process will be scheduled to run
m_exec_tid = Thread::current->tid();
auto old_page_directory = move(m_page_directory);
auto old_regions = move(m_regions);
m_page_directory = PageDirectory::create_for_userspace(*this);
#ifdef MM_DEBUG
dbg() << "Process " << pid() << " exec: PD=" << m_page_directory.ptr() << " created";
#endif
MM.enter_process_paging_scope(*this);
Region* region { nullptr };
InodeMetadata loader_metadata;
// FIXME: Hoooo boy this is a hack if I ever saw one.
// This is the 'random' offset we're giving to our ET_DYN exectuables to start as.
// It also happens to be the static Virtual Addresss offset every static exectuable gets :)
// Without this, some assumptions by the ELF loading hooks below are severely broken.
// 0x08000000 is a verified random number chosen by random dice roll https://xkcd.com/221/
u32 totally_random_offset = interpreter_description ? 0x08000000 : 0;
// FIXME: We should be able to load both the PT_INTERP interpreter and the main program... once the RTLD is smart enough
if (interpreter_description) {
loader_metadata = interpreter_description->metadata();
region = allocate_region_with_vmobject(VirtualAddress(), loader_metadata.size, *vmobject, 0, interpreter_description->absolute_path(), PROT_READ, false);
// we don't need the interpreter file desciption after we've loaded (or not) it into memory
interpreter_description = nullptr;
} else {
loader_metadata = main_program_description->metadata();
region = allocate_region_with_vmobject(VirtualAddress(), loader_metadata.size, *vmobject, 0, main_program_description->absolute_path(), PROT_READ, false);
}
ASSERT(region);
Region* master_tls_region { nullptr };
size_t master_tls_size = 0;
size_t master_tls_alignment = 0;
u32 entry_eip = 0;
OwnPtr<ELFLoader> loader;
{
ArmedScopeGuard rollback_regions_guard([&]() {
ASSERT(Process::current == this);
m_page_directory = move(old_page_directory);
m_regions = move(old_regions);
MM.enter_process_paging_scope(*this);
});
loader = make<ELFLoader>(region->vaddr().as_ptr(), loader_metadata.size);
// Load the correct executable -- either interp or main program.
// FIXME: Once we actually load both interp and main, we'll need to be more clever about this.
// In that case, both will be ET_DYN objects, so they'll both be completely relocatable.
// That means, we can put them literally anywhere in User VM space (ASLR anyone?).
// ALSO FIXME: Reminder to really really fix that 'totally random offset' business.
loader->map_section_hook = [&](VirtualAddress vaddr, size_t size, size_t alignment, size_t offset_in_image, bool is_readable, bool is_writable, bool is_executable, const String& name) -> u8* {
ASSERT(size);
ASSERT(alignment == PAGE_SIZE);
int prot = 0;
if (is_readable)
prot |= PROT_READ;
if (is_writable)
prot |= PROT_WRITE;
if (is_executable)
prot |= PROT_EXEC;
if (auto* region = allocate_region_with_vmobject(vaddr.offset(totally_random_offset), size, *vmobject, offset_in_image, String(name), prot))
return region->vaddr().as_ptr();
return nullptr;
};
loader->alloc_section_hook = [&](VirtualAddress vaddr, size_t size, size_t alignment, bool is_readable, bool is_writable, const String& name) -> u8* {
ASSERT(size);
ASSERT(alignment == PAGE_SIZE);
int prot = 0;
if (is_readable)
prot |= PROT_READ;
if (is_writable)
prot |= PROT_WRITE;
if (auto* region = allocate_region(vaddr.offset(totally_random_offset), size, String(name), prot))
return region->vaddr().as_ptr();
return nullptr;
};
// FIXME: Move TLS region allocation to userspace: LibC and the dynamic loader.
// LibC if we end up with a statically linked executable, and the
// dynamic loader so that it can create new TLS blocks for each shared libarary
// that gets loaded as part of DT_NEEDED processing, and via dlopen()
// If that doesn't happen quickly, at least pass the location of the TLS region
// some ELF Auxilliary Vector so the loader can use it/create new ones as necessary.
loader->tls_section_hook = [&](size_t size, size_t alignment) {
ASSERT(size);
master_tls_region = allocate_region({}, size, String(), PROT_READ | PROT_WRITE);
master_tls_size = size;
master_tls_alignment = alignment;
return master_tls_region->vaddr().as_ptr();
};
bool success = loader->load();
if (!success) {
kprintf("do_exec: Failure loading %s\n", path.characters());
return -ENOEXEC;
}
// FIXME: Validate that this virtual address is within executable region,
// instead of just non-null. You could totally have a DSO with entry point of
// the beginning of the text segement.
if (!loader->entry().offset(totally_random_offset).get()) {
kprintf("do_exec: Failure loading %s, entry pointer is invalid! (%p)\n", path.characters(), loader->entry().offset(totally_random_offset).get());
return -ENOEXEC;
}
rollback_regions_guard.disarm();
// NOTE: At this point, we've committed to the new executable.
entry_eip = loader->entry().offset(totally_random_offset).get();
kill_threads_except_self();
#ifdef EXEC_DEBUG
kprintf("Memory layout after ELF load:");
dump_regions();
#endif
}
m_elf_loader = move(loader);
m_executable = main_program_description->custody();
m_promises = m_execpromises;
m_veil_state = VeilState::None;
m_unveiled_paths.clear();
// Copy of the master TLS region that we will clone for new threads
m_master_tls_region = master_tls_region;
auto main_program_metadata = main_program_description->metadata();
if (!(main_program_description->custody()->mount_flags() & MS_NOSUID)) {
if (main_program_metadata.is_setuid())
m_euid = main_program_metadata.uid;
if (main_program_metadata.is_setgid())
m_egid = main_program_metadata.gid;
}
Thread::current->set_default_signal_dispositions();
Thread::current->m_signal_mask = 0;
Thread::current->m_pending_signals = 0;
m_futex_queues.clear();
m_region_lookup_cache = {};
disown_all_shared_buffers();
for (size_t i = 0; i < m_fds.size(); ++i) {
auto& daf = m_fds[i];
if (daf.description && daf.flags & FD_CLOEXEC) {
daf.description->close();
daf = {};
}
}
Thread* new_main_thread = nullptr;
if (Process::current == this) {
new_main_thread = Thread::current;
} else {
for_each_thread([&](auto& thread) {
new_main_thread = &thread;