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From: Florian Weimer <fweimer@redhat.com>
To: Andrei Vagin <avagin@gmail.com>
Cc: linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
	linux-um@lists.infradead.org, criu@openvz.org, avagin@google.com,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>,
	Anton Ivanov <anton.ivanov@cambridgegreys.com>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	Dmitry Safonov <0x7f454c46@gmail.com>,
	Ingo Molnar <mingo@redhat.com>, Jeff Dike <jdike@addtoit.com>,
	Mike Rapoport <rppt@linux.ibm.com>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	Oleg Nesterov <oleg@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Richard Weinberger <richard@nod.at>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 0/4 POC] Allow executing code and syscalls in another address space
Date: Wed, 14 Apr 2021 12:27:28 +0200	[thread overview]
Message-ID: <87blahb1pr.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <20210414055217.543246-1-avagin@gmail.com> (Andrei Vagin's message of "Tue, 13 Apr 2021 22:52:13 -0700")

* Andrei Vagin:

> We already have process_vm_readv and process_vm_writev to read and write
> to a process memory faster than we can do this with ptrace. And now it
> is time for process_vm_exec that allows executing code in an address
> space of another process. We can do this with ptrace but it is much
> slower.
>
> = Use-cases =

We also have some vaguely related within the same address space: running
code on another thread, without modifying its stack, while it has signal
handlers blocked, and without causing system calls to fail with EINTR.
This can be used to implement certain kinds of memory barriers.  It is
also necessary to implement set*id with POSIX semantics in userspace.
(Linux only changes the current thread credentials, POSIX requires
process-wide changes.)  We currently use a signal for set*id, but it has
issues (it can be blocked, the signal could come from somewhere, etc.).
We can't use signals for barriers because of the EINTR issue, and
because the signal context is stored on the stack.

Thanks,
Florian


  parent reply	other threads:[~2021-04-14 10:27 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-14  5:52 [PATCH 0/4 POC] Allow executing code and syscalls in another address space Andrei Vagin
2021-04-14  5:52 ` [PATCH 1/4] signal: add a helper to restore a process state from sigcontex Andrei Vagin
2021-04-14  5:52 ` [PATCH 2/4] arch/x86: implement the process_vm_exec syscall Andrei Vagin
2021-04-14 17:09   ` Oleg Nesterov
2021-04-23  6:59     ` Andrei Vagin
2021-06-28 16:13   ` Jann Horn
2021-06-28 16:30     ` Andy Lutomirski
2021-06-28 17:14       ` Jann Horn
2021-06-28 18:18         ` Eric W. Biederman
2021-06-29  1:01           ` Andrei Vagin
2021-07-02  6:22     ` Andrei Vagin
2021-07-02 11:51       ` Jann Horn
2021-07-02 20:40         ` Andy Lutomirski
2021-07-02  8:51   ` Peter Zijlstra
2021-07-02 22:21     ` Andrei Vagin
2021-07-02 20:56   ` Jann Horn
2021-07-02 22:48     ` Andrei Vagin
2021-04-14  5:52 ` [PATCH 3/4] arch/x86: allow to execute syscalls via process_vm_exec Andrei Vagin
2021-04-14  5:52 ` [PATCH 4/4] selftests: add tests for process_vm_exec Andrei Vagin
2021-04-14  6:46 ` [PATCH 0/4 POC] Allow executing code and syscalls in another address space Jann Horn
2021-04-14 22:10   ` Andrei Vagin
2021-07-02  6:57   ` Andrei Vagin
2021-07-02 15:12     ` Jann Horn
2021-07-18  0:38       ` Andrei Vagin
2021-04-14  7:22 ` Anton Ivanov
2021-04-14  7:34   ` Johannes Berg
2021-04-14  9:24     ` Benjamin Berg
2021-04-14 10:27 ` Florian Weimer [this message]
2021-04-14 11:24   ` Jann Horn
2021-04-14 12:20     ` Florian Weimer
2021-04-14 13:58       ` Jann Horn
2021-04-16 19:29 ` Kirill Smelkov
2021-04-17 16:28 ` sbaugh
2021-07-02 22:44 ` Andy Lutomirski
2021-07-18  1:34   ` Andrei Vagin

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