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[209.85.220.65]) by mx.google.com with SMTPS id o9sor11243746pgv.33.2019.04.01.09.05.02 for (Google Transport Security); Mon, 01 Apr 2019 09:05:02 -0700 (PDT) Received-SPF: pass (google.com: domain of andreyknvl@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=Wiac3r+A; spf=pass (google.com: domain of andreyknvl@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=andreyknvl@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=LBH0UFdr1G0TFY5RWwm4Ys2pzrC+F6X1ZFx+vMAYO5U=; b=Wiac3r+ALQiP5hRLiFpFfNVQivXgrfv4TMKkQPmMbSHzjlhVzItXRCbrTEKJuI1VjN s0MgQzU5+Qoppw1+RUix1XPz0+BR6zUFiQavwlY3pCjSv3p5oTSh7C21sNRrkcLwoVii E6qYdQZ/ILOMHDlAX3hvPz5LKX8XhDisRnGVJcc7GzBG8mNjsjDuLnDfVGUgM90E0X5S HzG8DgysBZdMpESegwv9cPMZg/HQyktCeIGgj1DOs4ldaWq1RZPA/u6i7USRvPEoMpql 6E9+TiicLKRnTU63Hwp3v9CjvvkhQSCftl2A/I48b7hiHCdIrCtizZvFgsEdMJ+ocqBG 73eA== X-Google-Smtp-Source: APXvYqyLseS+mUC5w0QaVtnLgSzLk0ge1hOeF6fc30VkKh2qR+OIgQEFLhyguAEdVZXVxknKXm92fbIwJNhY4gjXJZE= X-Received: by 2002:a63:c944:: with SMTP id y4mr14537047pgg.257.1554134701531; Mon, 01 Apr 2019 09:05:01 -0700 (PDT) MIME-Version: 1.0 References: <2280b62096ce1fa5c9e9429d18f08f82f4be1b0b.1553093421.git.andreyknvl@google.com> <20190322120434.GD13384@arrakis.emea.arm.com> In-Reply-To: From: Andrey Konovalov Date: Mon, 1 Apr 2019 18:04:50 +0200 Message-ID: Subject: Re: [PATCH v13 09/20] net, arm64: untag user pointers in tcp_zerocopy_receive To: Kevin Brodsky Cc: Catalin Marinas , Will Deacon , Mark Rutland , Robin Murphy , Kees Cook , Kate Stewart , Greg Kroah-Hartman , Andrew Morton , Ingo Molnar , "Kirill A . Shutemov" , Shuah Khan , Vincenzo Frascino , Eric Dumazet , "David S. Miller" , Alexei Starovoitov , Daniel Borkmann , Steven Rostedt , Ingo Molnar , Peter Zijlstra , Arnaldo Carvalho de Melo , Alex Deucher , =?UTF-8?Q?Christian_K=C3=B6nig?= , "David (ChunMing) Zhou" , Yishai Hadas , Mauro Carvalho Chehab , Jens Wiklander , Alex Williamson , Linux ARM , Linux Memory Management List , linux-arch , netdev , bpf , amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, "open list:KERNEL SELFTEST FRAMEWORK" , LKML , Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Chintan Pandya , Luc Van Oostenryck , Dave Martin , Szabolcs Nagy Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Mar 25, 2019 at 2:54 PM Kevin Brodsky wrote: > > On 22/03/2019 12:04, Catalin Marinas wrote: > > On Wed, Mar 20, 2019 at 03:51:23PM +0100, Andrey Konovalov wrote: > >> This patch is a part of a series that extends arm64 kernel ABI to allow to > >> pass tagged user pointers (with the top byte set to something else other > >> than 0x00) as syscall arguments. > >> > >> tcp_zerocopy_receive() uses provided user pointers for vma lookups, which > >> can only by done with untagged pointers. > >> > >> Untag user pointers in this function. > >> > >> Signed-off-by: Andrey Konovalov > >> --- > >> net/ipv4/tcp.c | 2 ++ > >> 1 file changed, 2 insertions(+) > >> > >> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c > >> index 6baa6dc1b13b..855a1f68c1ea 100644 > >> --- a/net/ipv4/tcp.c > >> +++ b/net/ipv4/tcp.c > >> @@ -1761,6 +1761,8 @@ static int tcp_zerocopy_receive(struct sock *sk, > >> if (address & (PAGE_SIZE - 1) || address != zc->address) > >> return -EINVAL; > >> > >> + address = untagged_addr(address); > >> + > >> if (sk->sk_state == TCP_LISTEN) > >> return -ENOTCONN; > > I don't think we need this patch if we stick to Vincenzo's ABI > > restrictions. Can zc->address be an anonymous mmap()? My understanding > > of TCP_ZEROCOPY_RECEIVE is that this is an mmap() on a socket, so user > > should not tag such pointer. > > Good point, I hadn't looked into the interface properly. The `vma->vm_ops != > &tcp_vm_ops` check just below makes sure that the mapping is specifically tied to a > TCP socket, so definitely not included in the ABI relaxation. > > > We want to allow tagged pointers to work transparently only for heap and > > stack, hence the restriction to anonymous mmap() and those addresses > > below sbrk(0). Right, I'll drop this patch, thanks for noticing! > > That's not quite true: in the ABI relaxation v2, all private mappings that are either > anonymous or backed by a regular file are included. The scope is quite a bit larger > than heap and stack, even though this is what we're primarily interested in for now. > > Kevin