From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Jann Horn <jannh@google.com>
Cc: Andrii Nakryiko <andriin@fb.com>, bpf <bpf@vger.kernel.org>,
Network Development <netdev@vger.kernel.org>,
Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii.nakryiko@gmail.com>,
Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH bpf] bpf: prevent mmap()'ing read-only maps as writable
Date: Wed, 20 May 2020 20:29:31 -0700 [thread overview]
Message-ID: <20200521032931.rs5vbob2gei6ccic@ast-mbp.dhcp.thefacebook.com> (raw)
In-Reply-To: <CAG48ez2HZfjCKG+coVq2k9eE_Hm0rsdQE=O=5nVyKL80QncVZA@mail.gmail.com>
On Thu, May 21, 2020 at 04:50:32AM +0200, Jann Horn wrote:
> On Tue, May 19, 2020 at 7:38 AM Andrii Nakryiko <andriin@fb.com> wrote:
> > As discussed in [0], it's dangerous to allow mapping BPF map, that's meant to
> > be frozen and is read-only on BPF program side, because that allows user-space
> > to actually store a writable view to the page even after it is frozen. This is
> > exacerbated by BPF verifier making a strong assumption that contents of such
> > frozen map will remain unchanged. To prevent this, disallow mapping
> > BPF_F_RDONLY_PROG mmap()'able BPF maps as writable, ever.
> >
> > [0] https://lore.kernel.org/bpf/CAEf4BzYGWYhXdp6BJ7_=9OQPJxQpgug080MMjdSB72i9R+5c6g@mail.gmail.com/
> >
> > Suggested-by: Jann Horn <jannh@google.com>
> > Fixes: fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY")
> > Signed-off-by: Andrii Nakryiko <andriin@fb.com>
>
> Reviewed-by: Jann Horn <jannh@google.com>
I fixed trailing white space after 'writable page'
and applied to bpf tree.
Thanks
prev parent reply other threads:[~2020-05-21 3:29 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 5:38 [PATCH bpf] bpf: prevent mmap()'ing read-only maps as writable Andrii Nakryiko
2020-05-21 2:50 ` Jann Horn
2020-05-21 3:29 ` Alexei Starovoitov [this message]
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