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/*
* Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
* Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
* 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/ScopeGuard.h>
#include <Kernel/Process.h>
#include <Kernel/VM/MemoryManager.h>
#include <Kernel/VM/PrivateInodeVMObject.h>
#include <Kernel/VM/ProcessPagingScope.h>
#include <Kernel/VM/Region.h>
#include <Kernel/VM/SharedInodeVMObject.h>
namespace Kernel {
static KResultOr<u32> handle_ptrace(const Kernel::Syscall::SC_ptrace_params& params, Process& caller)
{
ScopedSpinLock scheduler_lock(g_scheduler_lock);
if (params.request == PT_TRACE_ME) {
if (Process::current()->tracer())
return EBUSY;
caller.set_wait_for_tracer_at_next_execve(true);
return KSuccess;
}
// FIXME: PID/TID BUG
// This bug allows to request PT_ATTACH (or anything else) the same process, as
// long it is not the main thread. Alternatively, if this is desired, then the
// bug is that this prevents PT_ATTACH to the main thread from another thread.
if (params.tid == caller.pid().value())
return EINVAL;
auto peer = Thread::from_tid(params.tid);
if (!peer)
return ESRCH;
Locker ptrace_locker(peer->process().ptrace_lock());
if ((peer->process().uid() != caller.euid())
|| (peer->process().uid() != peer->process().euid())) // Disallow tracing setuid processes
return EACCES;
if (!peer->process().is_dumpable())
return EACCES;
auto& peer_process = peer->process();
if (params.request == PT_ATTACH) {
if (peer_process.tracer()) {
return EBUSY;
}
peer_process.start_tracing_from(caller.pid());
ScopedSpinLock lock(peer->get_lock());
if (peer->state() != Thread::State::Stopped) {
peer->send_signal(SIGSTOP, &caller);
}
return KSuccess;
}
auto* tracer = peer_process.tracer();
if (!tracer)
return EPERM;
if (tracer->tracer_pid() != caller.pid())
return EBUSY;
if (peer->state() == Thread::State::Running)
return EBUSY;
scheduler_lock.unlock();
switch (params.request) {
case PT_CONTINUE:
peer->send_signal(SIGCONT, &caller);
break;
case PT_DETACH:
peer_process.stop_tracing();
peer->send_signal(SIGCONT, &caller);
break;
case PT_SYSCALL:
tracer->set_trace_syscalls(true);
peer->send_signal(SIGCONT, &caller);
break;
case PT_GETREGS: {
if (!tracer->has_regs())
return EINVAL;
auto* regs = reinterpret_cast<PtraceRegisters*>(params.addr);
if (!copy_to_user(regs, &tracer->regs()))
return EFAULT;
break;
}
case PT_SETREGS: {
if (!tracer->has_regs())
return EINVAL;
PtraceRegisters regs {};
if (!copy_from_user(®s, (const PtraceRegisters*)params.addr))
return EFAULT;
auto& peer_saved_registers = peer->get_register_dump_from_stack();
// Verify that the saved registers are in usermode context
if ((peer_saved_registers.cs & 0x03) != 3)
return EFAULT;
tracer->set_regs(regs);
copy_ptrace_registers_into_kernel_registers(peer_saved_registers, regs);
break;
}
case PT_PEEK: {
Kernel::Syscall::SC_ptrace_peek_params peek_params {};
if (!copy_from_user(&peek_params, reinterpret_cast<Kernel::Syscall::SC_ptrace_peek_params*>(params.addr)))
return EFAULT;
if (!is_user_address(VirtualAddress { peek_params.address }))
return EFAULT;
auto result = peer->process().peek_user_data(Userspace<const u32*> { (FlatPtr)peek_params.address });
if (result.is_error())
return result.error();
if (!copy_to_user(peek_params.out_data, &result.value()))
return EFAULT;
break;
}
case PT_POKE:
if (!is_user_address(VirtualAddress { params.addr }))
return EFAULT;
return peer->process().poke_user_data(Userspace<u32*> { (FlatPtr)params.addr }, params.data);
default:
return EINVAL;
}
return KSuccess;
}
KResultOr<int> Process::sys$ptrace(Userspace<const Syscall::SC_ptrace_params*> user_params)
{
REQUIRE_PROMISE(ptrace);
Syscall::SC_ptrace_params params {};
if (!copy_from_user(¶ms, user_params))
return EFAULT;
auto result = handle_ptrace(params, *this);
return result.is_error() ? result.error().error() : result.value();
}
/**
* "Does this process have a thread that is currently being traced by the provided process?"
*/
bool Process::has_tracee_thread(ProcessID tracer_pid)
{
if (auto tracer = this->tracer())
return tracer->tracer_pid() == tracer_pid;
return false;
}
KResultOr<u32> Process::peek_user_data(Userspace<const u32*> address)
{
uint32_t result;
// This function can be called from the context of another
// process that called PT_PEEK
ProcessPagingScope scope(*this);
if (!copy_from_user(&result, address)) {
dbgln("Invalid address for peek_user_data: {}", address.ptr());
return EFAULT;
}
return result;
}
KResult Process::poke_user_data(Userspace<u32*> address, u32 data)
{
Range range = { VirtualAddress(address), sizeof(u32) };
auto* region = space().find_region_containing(range);
if (!region)
return EFAULT;
ProcessPagingScope scope(*this);
if (region->is_shared()) {
// If the region is shared, we change its vmobject to a PrivateInodeVMObject
// to prevent the write operation from changing any shared inode data
VERIFY(region->vmobject().is_shared_inode());
region->set_vmobject(PrivateInodeVMObject::create_with_inode(static_cast<SharedInodeVMObject&>(region->vmobject()).inode()));
region->set_shared(false);
}
const bool was_writable = region->is_writable();
if (!was_writable) {
region->set_writable(true);
region->remap();
}
ScopeGuard rollback([&]() {
if (!was_writable) {
region->set_writable(false);
region->remap();
}
});
if (!copy_to_user(address, &data)) {
dbgln("poke_user_data: Bad address {:p}", address.ptr());
return EFAULT;
}
return KSuccess;
}
}
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