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Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs

From Alexei Starovoitov <ast@plumgrid.com>
Newsgroups linux.kernel
Subject Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs
Date 2015-10-18 23:00 +0200
Message-ID <ql3dE-8hp-3@gated-at.bofh.it> (permalink)
References (10 earlier) <qkpJf-yI-1@gated-at.bofh.it> <qkyMz-5GA-41@gated-at.bofh.it> <qkNVh-2KP-61@gated-at.bofh.it> <qkXKW-mZ-9@gated-at.bofh.it> <qkZjH-2st-5@gated-at.bofh.it>
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On 10/18/15 9:49 AM, Daniel Borkmann wrote:
> Okay, I have pushed some rough working proof of concept here:
>
> https://git.breakpoint.cc/cgit/dborkman/net-next.git/log/?h=ebpf-fds-final5
>
> So the idea eventually had to be slightly modified after giving this
> further
> thoughts and is the following:
>
> We have 3 commands (BPF_DEV_CREATE, BPF_DEV_DESTROY, BPF_DEV_CONNECT), and
> related to that a bpf_attr extension with only a single __u32 fd member
> in it.
...
> The nice thing about it is that you can create/unlink as many as you
> want, but
> when you remove the real device from an application via
> bpf_dev_destroy(fd),
> then all links disappear with it. Just like in the case of a normal
> device driver.

interesting idea!
What happens if user app creates a dev via bpf_dev_create(), exits and
then admin does rm of that dev ?
Looks like map/prog will leak ?
So the only proper way to delete such cdevs is via bpf_dev_destroy ?

> On device creation, the kernel will return the minor number via bpf(2),
> so you
> can access the file easily, f.e. /dev/bpf/bpf_map<minor> resp.
> /dev/bpf/bpf_prog<minor>,
> and then move on with mknod(2) or symlink(2) from there if wished.

what if admin mknod in that dir with some arbitrary minor ?
mknod will succeed, but it won't hold anything?
looks like bpf_dev_connect will handle it gracefully.
So these cdevs should only be created and destroyed via bpf syscall
and only sensible operations on them is open() to get fd and pass
to bpf_dev_connect and symlink. Anything else admin should be
careful not to do. Right?

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[PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-16 03:20 +0200
  Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Hannes Frederic Sowa <hannes@stressinduktion.org> - 2015-10-16 12:30 +0200
    Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-16 15:40 +0200
      Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Hannes Frederic Sowa <hannes@stressinduktion.org> - 2015-10-16 18:40 +0200
        Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-16 19:30 +0200
          Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-16 19:40 +0200
    Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-16 18:20 +0200
      Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Hannes Frederic Sowa <hannes@stressinduktion.org> - 2015-10-16 18:50 +0200
        Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Thomas Graf <tgraf@suug.ch> - 2015-10-16 19:40 +0200
        Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-16 19:40 +0200
  Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Hannes Frederic Sowa <hannes@stressinduktion.org> - 2015-10-16 19:30 +0200
    Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-16 19:50 +0200
      Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-16 20:00 +0200
        Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs ebiederm@xmission.com (Eric W. Biederman) - 2015-10-16 21:00 +0200
          Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-16 21:30 +0200
            Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-16 22:00 +0200
            Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs ebiederm@xmission.com (Eric W. Biederman) - 2015-10-16 22:10 +0200
              Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-16 23:00 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs ebiederm@xmission.com (Eric W. Biederman) - 2015-10-17 02:00 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-17 04:50 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-17 14:30 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-18 06:40 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-18 17:10 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-18 18:50 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-18 23:00 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Hannes Frederic Sowa <hannes@stressinduktion.org> - 2015-10-19 09:40 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-19 12:00 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-19 16:30 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-19 18:30 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-19 19:40 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-19 20:20 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Hannes Frederic Sowa <hannes@stressinduktion.org> - 2015-10-19 20:50 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-19 21:40 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Hannes Frederic Sowa <hannes@stressinduktion.org> - 2015-10-19 22:10 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-19 22:50 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-20 00:20 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-20 02:40 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-20 10:50 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-20 20:00 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs ebiederm@xmission.com (Eric W. Biederman) - 2015-10-20 21:10 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-21 17:20 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Thomas Graf <tgraf@suug.ch> - 2015-10-21 20:40 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-22 00:50 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-22 15:30 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs ebiederm@xmission.com (Eric W. Biederman) - 2015-10-22 21:50 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Daniel Borkmann <daniel@iogearbox.net> - 2015-10-23 15:50 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Hannes Frederic Sowa <hannes@stressinduktion.org> - 2015-10-20 11:50 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Hannes Frederic Sowa <hannes@stressinduktion.org> - 2015-10-20 01:10 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-20 03:10 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Hannes Frederic Sowa <hannes@stressinduktion.org> - 2015-10-20 12:10 +0200
                Re: [PATCH net-next 3/4] bpf: add support for persistent maps/progs Alexei Starovoitov <ast@plumgrid.com> - 2015-10-20 20:50 +0200

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