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From: Mircea CIRJALIU - MELIU <mcirjaliu@bitdefender.com>
To: "Andy Lutomirski" <luto@kernel.org>,
	"Adalbert Lazăr" <alazar@bitdefender.com>
Cc: Linux-MM <linux-mm@kvack.org>,
	"Linux API" <linux-api@vger.kernel.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Alexander Graf" <graf@amazon.com>,
	"Stefan Hajnoczi" <stefanha@redhat.com>,
	"Jerome Glisse" <jglisse@redhat.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Mihai Donțu" <mdontu@bitdefender.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Sargun Dhillon" <sargun@sargun.me>,
	"Aleksa Sarai" <cyphar@cyphar.com>,
	"Oleg Nesterov" <oleg@redhat.com>, "Jann Horn" <jannh@google.com>,
	"Kees Cook" <keescook@chromium.org>,
	"Matthew Wilcox" <willy@infradead.org>,
	"Christian Brauner" <christian.brauner@ubuntu.com>
Subject: RE: [RESEND RFC PATCH 0/5] Remote mapping
Date: Mon, 7 Sep 2020 10:25:50 +0000	[thread overview]
Message-ID: <AM7PR02MB6082589CFC5C0C2848495553BB280@AM7PR02MB6082.eurprd02.prod.outlook.com> (raw)
In-Reply-To: <CALCETrVc0RCcvVhxL=x2ics-Snhh1F6o5M7EVsA2rPYcaynMyA@mail.gmail.com>

> From: Andy Lutomirski <luto@kernel.org>
> I think this is very clever, but I find myself wondering what happens if people
> start trying to abuse this by, for example, setting up a remote mapping
> pointing to fun regions like userfaultfd or another remote mapping.

Can ptrace() be used to abuse fun regions of a process address space?
Remote mapping recursiveness can be eliminated by checking the VMA the
remote page is extracted from. (NYI)

> I'm a little concerned that it's actually too clever and that maybe a more
> straightforward solution should be investigated.  I personally rather dislike
> the KVM model in which the guest address space mirrors the host (QEMU)
> address space rather than being its own thing.

I've seen a few internal mmap()s throughout the kernel. Just wondering how
memory accounting is implemented for these cases. Will this be reflected in
the memory usage of the process that controls such a module? Especially in
the case of a virtual machine that needs a few GBs of memory.

Mircea


  parent reply	other threads:[~2020-09-07 10:26 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-04 11:31 [RESEND RFC PATCH 0/5] Remote mapping Adalbert Lazăr
2020-09-04 11:31 ` [RESEND RFC PATCH 1/5] mm: add atomic capability to zap_details Adalbert Lazăr
2020-09-04 11:31 ` [RESEND RFC PATCH 2/5] mm: let the VMA decide how zap_pte_range() acts on mapped pages Adalbert Lazăr
2020-09-04 11:31 ` [RESEND RFC PATCH 3/5] mm/mmu_notifier: remove lockdep map, allow mmu notifier to be used in nested scenarios Adalbert Lazăr
2020-09-04 12:03   ` Jason Gunthorpe
2020-09-04 11:31 ` [RESEND RFC PATCH 4/5] mm/remote_mapping: use a pidfd to access memory belonging to unrelated process Adalbert Lazăr
2020-09-04 17:55   ` Oleg Nesterov
2020-09-07 14:30   ` Oleg Nesterov
2020-09-07 15:16     ` Adalbert Lazăr
2020-09-09  8:32     ` Mircea CIRJALIU - MELIU
2020-09-10 16:43       ` Oleg Nesterov
2020-09-07 15:02   ` Christian Brauner
2020-09-07 16:04     ` Mircea CIRJALIU - MELIU
2020-09-04 11:31 ` [RESEND RFC PATCH 5/5] pidfd_mem: implemented remote memory mapping system call Adalbert Lazăr
2020-09-04 19:18   ` Florian Weimer
2020-09-07 14:55   ` Christian Brauner
2020-09-04 12:11 ` [RESEND RFC PATCH 0/5] Remote mapping Jason Gunthorpe
2020-09-04 13:24   ` Mircea CIRJALIU - MELIU
2020-09-04 13:39     ` Jason Gunthorpe
2020-09-04 14:18       ` Mircea CIRJALIU - MELIU
2020-09-04 14:39         ` Jason Gunthorpe
2020-09-04 15:40           ` Mircea CIRJALIU - MELIU
2020-09-04 16:11             ` Jason Gunthorpe
2020-09-04 19:41   ` Matthew Wilcox
2020-09-04 19:49     ` Jason Gunthorpe
2020-09-04 20:08     ` Paolo Bonzini
2020-12-01 18:01     ` Jason Gunthorpe
2020-09-04 19:19 ` Florian Weimer
2020-09-04 20:18   ` Paolo Bonzini
2020-09-07  8:33     ` Christian Brauner
2020-09-04 19:39 ` Andy Lutomirski
2020-09-04 20:09   ` Paolo Bonzini
2020-09-04 20:34     ` Andy Lutomirski
2020-09-04 21:58       ` Paolo Bonzini
2020-09-04 23:17         ` Andy Lutomirski
2020-09-05 18:27           ` Paolo Bonzini
2020-09-07  8:38             ` Christian Brauner
2020-09-07 12:41           ` Mircea CIRJALIU - MELIU
2020-09-07  7:05         ` Christoph Hellwig
2020-09-07  8:44           ` Paolo Bonzini
2020-09-07 10:25   ` Mircea CIRJALIU - MELIU [this message]
2020-09-07 15:05 ` Christian Brauner
2020-09-07 20:43   ` Andy Lutomirski
2020-09-09 11:38     ` Stefan Hajnoczi

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