From: Christian Brauner <brauner@kernel.org>
To: David Howells <dhowells@redhat.com>
Cc: Andrew Lunn <andrew@lunn.ch>, Eric Dumazet <edumazet@google.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
David Hildenbrand <david@redhat.com>,
John Hubbard <jhubbard@nvidia.com>,
Christoph Hellwig <hch@infradead.org>,
willy@infradead.org, Al Viro <viro@zeniv.linux.org.uk>,
Miklos Szeredi <mszeredi@redhat.com>,
torvalds@linux-foundation.org, netdev@vger.kernel.org,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: AF_UNIX/zerocopy/pipe/vmsplice/splice vs FOLL_PIN
Date: Mon, 23 Jun 2025 13:50:20 +0200 [thread overview]
Message-ID: <20250623-absetzbar-barzahlung-3d124847a2b4@brauner> (raw)
In-Reply-To: <2135907.1747061490@warthog.procyon.org.uk>
On Mon, May 12, 2025 at 03:51:30PM +0100, David Howells wrote:
> I'm looking at how to make sendmsg() handle page pinning - and also working
> towards supporting the page refcount eventually being removed and only being
> available with certain memory types.
>
> One of the outstanding issues is in sendmsg(). Analogously with DIO writes,
> sendmsg() should be pinning memory (FOLL_PIN/GUP) rather than simply getting
> refs on it before it attaches it to an sk_buff. Without this, if memory is
> spliced into an AF_UNIX socket and then the process forks, that memory gets
> attached to the child process, and the child can alter the data, probably by
> accident, if the memory is on the stack or in the heap.
>
> Further, kernel services can use MSG_SPLICE_PAGES to attach memory directly to
> an AF_UNIX pipe (though I'm not sure if anyone actually does this).
I would possible be interested in using this for the coredump af_unix socket.
next prev parent reply other threads:[~2025-06-23 11:50 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <0aa1b4a2-47b2-40a4-ae14-ce2dd457a1f7@lunn.ch>
[not found] ` <1015189.1746187621@warthog.procyon.org.uk>
2025-05-02 13:41 ` MSG_ZEROCOPY and the O_DIRECT vs fork() race David Howells
2025-05-02 13:48 ` David Hildenbrand
2025-05-02 14:21 ` Andrew Lunn
2025-05-02 16:21 ` Reorganising how the networking layer handles memory David Howells
2025-05-05 20:14 ` Jakub Kicinski
2025-05-06 13:50 ` David Howells
2025-05-06 13:56 ` Christoph Hellwig
2025-05-06 18:20 ` Jakub Kicinski
2025-05-07 13:45 ` David Howells
2025-05-07 17:47 ` Willem de Bruijn
2025-05-07 13:49 ` David Howells
2025-05-12 14:51 ` AF_UNIX/zerocopy/pipe/vmsplice/splice vs FOLL_PIN David Howells
2025-05-12 21:59 ` David Hildenbrand
2025-06-23 11:50 ` Christian Brauner [this message]
2025-06-23 13:53 ` Christoph Hellwig
2025-06-23 14:16 ` David Howells
2025-06-23 10:50 ` How to handle P2P DMA with only {physaddr,len} in bio_vec? David Howells
2025-06-23 13:46 ` Christoph Hellwig
2025-06-23 23:38 ` Alistair Popple
2025-06-24 9:02 ` David Howells
2025-06-24 12:18 ` Jason Gunthorpe
2025-06-24 12:39 ` Christoph Hellwig
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