Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <cover.1552679409.git.andreyknvl@google.com> <56d3373c1c5007d776fcd5de4523f4b9da341fb6.1552679409.git.andreyknvl@google.com>
 <04c5b2de-7fde-7625-9d42-228160879ea0@gmail.com>
In-Reply-To: <04c5b2de-7fde-7625-9d42-228160879ea0@gmail.com>
From:   Andrey Konovalov <andreyknvl@google.com>
Date:   Mon, 18 Mar 2019 14:14:33 +0100
Message-ID: <CAAeHK+xXLypBpF1EE73KuzQAo0E6Y=apS46wo+swo2AB6cy3YA@mail.gmail.com>
Subject: Re: [PATCH v11 08/14] net, arm64: untag user pointers in tcp_zerocopy_receive
To:     Eric Dumazet <eric.dumazet@gmail.com>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Kees Cook <keescook@chromium.org>,
        Kate Stewart <kstewart@linuxfoundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Ingo Molnar <mingo@kernel.org>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Shuah Khan <shuah@kernel.org>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Eric Dumazet <edumazet@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>, bpf@vger.kernel.org,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Dmitry Vyukov <dvyukov@google.com>,
        Kostya Serebryany <kcc@google.com>,
        Evgeniy Stepanov <eugenis@google.com>,
        Lee Smith <Lee.Smith@arm.com>,
        Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
        Jacob Bramley <Jacob.Bramley@arm.com>,
        Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>,
        Chintan Pandya <cpandya@codeaurora.org>,
        Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
        Dave Martin <Dave.Martin@arm.com>,
        Kevin Brodsky <kevin.brodsky@arm.com>,
        Szabolcs Nagy <Szabolcs.Nagy@arm.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, Mar 15, 2019 at 9:03 PM Eric Dumazet <eric.dumazet@gmail.com> wrote:
>
>
>
> On 03/15/2019 12:51 PM, 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 <andreyknvl@google.com>
> > ---
> >  net/ipv4/tcp.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> > index 6baa6dc1b13b..89db3b4fc753 100644
> > --- a/net/ipv4/tcp.c
> > +++ b/net/ipv4/tcp.c
> > @@ -1758,6 +1758,8 @@ static int tcp_zerocopy_receive(struct sock *sk,
> >       int inq;
> >       int ret;
> >
> > +     address = untagged_addr(address);
> > +
> >       if (address & (PAGE_SIZE - 1) || address != zc->address)
>
> The second test will fail, if the top bits are changed in address but not in zc->address

Will fix in v12, thanks Eric!

>
> >               return -EINVAL;
> >
> >
>