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Kernel: Add 'ptrace' syscall

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This commit adds a basic implementation of
the ptrace syscall, which allows one process
(the tracer) to control another process (the tracee).

While a process is being traced, it is stopped whenever a signal is
received (other than SIGCONT).

The tracer can start tracing another thread with PT_ATTACH,
which causes the tracee to stop.

From there, the tracer can use PT_CONTINUE
to continue the execution of the tracee,
or use other request codes (which haven't been implemented yet)
to modify the state of the tracee.

Additional request codes are PT_SYSCALL, which causes the tracee to
continue exection but stop at the next entry or exit from a syscall,
and PT_GETREGS which fethces the last saved register set of the tracee
(can be used to inspect syscall arguments and return value).

A special request code is PT_TRACE_ME, which is issued by the tracee
and causes it to stop when it calls execve and wait for the
tracer to attach.
This commit is contained in:
Itamar 2020-03-28 11:47:16 +03:00 • committed by Andreas Kling
parent c9396be83f
commit 6b74d38aab
13 changed files with 300 additions and 102 deletions
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63
Kernel/ProcessTracer.cpp
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@ -1,63 +0,0 @@
/*
* Copyright (c) 2018-2020, 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/Memory.h>
#include <Kernel/ProcessTracer.h>
namespace Kernel {
ProcessTracer::ProcessTracer(pid_t pid)
: m_pid(pid)
{
}
ProcessTracer::~ProcessTracer()
{
}
void ProcessTracer::did_syscall(u32 function, u32 arg1, u32 arg2, u32 arg3, u32 result)
{
CallData data = { function, arg1, arg2, arg3, result };
m_calls.enqueue(data);
}
int ProcessTracer::read(FileDescription&, u8* buffer, int buffer_size)
{
if (m_calls.is_empty())
return 0;
auto data = m_calls.dequeue();
// FIXME: This should not be an assertion.
ASSERT(buffer_size == sizeof(data));
memcpy(buffer, &data, sizeof(data));
return sizeof(data);
}
String ProcessTracer::absolute_path(const FileDescription&) const
{
return String::format("tracer:%d", m_pid);
}
}