[v3,bpf-next,0/2] BPF iterator for UNIX domain socket.

This patch set adds BPF iterator support for UNIX domain socket.  The first
patch implements it and the second adds a selftest.


Changelog:
  v3:
  - Export some functions for CONFIG_UNIX=m

  v2:
  https://lore.kernel.org/netdev/20210803011110.21205-1-kuniyu@amazon.co.jp/
  - Implement bpf_iter specific seq_ops->stop()
  - Add bpf_iter__unix in bpf_iter.h
  - Move common definitions in selftest to bpf_tracing_net.h
  - Include the code for abstract UNIX domain socket as comment in selftest
  - Use ASSERT_OK_PTR() instead of CHECK()
  - Make ternary operators on single line

  v1:
  https://lore.kernel.org/netdev/20210729233645.4869-1-kuniyu@amazon.co.jp/


Kuniyuki Iwashima (2):
  bpf: af_unix: Implement BPF iterator for UNIX domain socket.
  selftest/bpf: Implement sample UNIX domain socket iterator program.

 fs/proc/proc_net.c                            |  2 +
 include/linux/btf_ids.h                       |  3 +-
 kernel/bpf/bpf_iter.c                         |  3 +
 net/core/filter.c                             |  1 +
 net/unix/af_unix.c                            | 93 +++++++++++++++++++
 .../selftests/bpf/prog_tests/bpf_iter.c       | 16 ++++
 tools/testing/selftests/bpf/progs/bpf_iter.h  |  8 ++
 .../selftests/bpf/progs/bpf_iter_unix.c       | 86 +++++++++++++++++
 .../selftests/bpf/progs/bpf_tracing_net.h     |  4 +
 9 files changed, 215 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_unix.c

On 8/4/21 12:08 AM, Kuniyuki Iwashima wrote:
> This patch implements the BPF iterator for the UNIX domain socket and

> exports some functions under GPL for the CONFIG_UNIX=m case.

> 

> Currently, the batch optimization introduced for the TCP iterator in the

> commit 04c7820b776f ("bpf: tcp: Bpf iter batching and lock_sock") is not

> applied.  It will require replacing the big lock for the hash table with

> small locks for each hash list not to block other processes.

> 

> Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>

> ---

>   fs/proc/proc_net.c      |  2 +

>   include/linux/btf_ids.h |  3 +-

>   kernel/bpf/bpf_iter.c   |  3 ++

>   net/core/filter.c       |  1 +

>   net/unix/af_unix.c      | 93 +++++++++++++++++++++++++++++++++++++++++

>   5 files changed, 101 insertions(+), 1 deletion(-)

> 

> diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c

> index 15c2e55d2ed2..887a8102da9f 100644

> --- a/fs/proc/proc_net.c

> +++ b/fs/proc/proc_net.c

> @@ -91,6 +91,7 @@ int bpf_iter_init_seq_net(void *priv_data, struct bpf_iter_aux_info *aux)

>   #endif

>   	return 0;

>   }

> +EXPORT_SYMBOL_GPL(bpf_iter_init_seq_net);


bpf_iter does not support modules for now as it is implemented before 
module btf support. It needs some changes.
For example, currently bpf_iter only caches/uses the vmlinux btf_id
and module obj_id and module btf_id is not used.
One example is ipv6 and bpf_iter is guarded with IS_BUILTIN(CONFIG_IPV6).

So you could (1) add btf_iter support module btf in this patch set, or
(2). check IS_BUILTIN(CONFIG_UNIX). (2) might be easier and you can have
a subsequent patch set to add module support for bpf_iter. But it is
up to you.

>   

>   void bpf_iter_fini_seq_net(void *priv_data)

>   {

> @@ -100,6 +101,7 @@ void bpf_iter_fini_seq_net(void *priv_data)

>   	put_net(p->net);

>   #endif

[...]

From:   Yonghong Song <yhs@fb.com>

Date:   Thu, 5 Aug 2021 09:53:40 -0700
> On 8/4/21 12:08 AM, Kuniyuki Iwashima wrote:

> > This patch implements the BPF iterator for the UNIX domain socket and

> > exports some functions under GPL for the CONFIG_UNIX=m case.

> > 

> > Currently, the batch optimization introduced for the TCP iterator in the

> > commit 04c7820b776f ("bpf: tcp: Bpf iter batching and lock_sock") is not

> > applied.  It will require replacing the big lock for the hash table with

> > small locks for each hash list not to block other processes.

> > 

> > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>

> > ---

> >   fs/proc/proc_net.c      |  2 +

> >   include/linux/btf_ids.h |  3 +-

> >   kernel/bpf/bpf_iter.c   |  3 ++

> >   net/core/filter.c       |  1 +

> >   net/unix/af_unix.c      | 93 +++++++++++++++++++++++++++++++++++++++++

> >   5 files changed, 101 insertions(+), 1 deletion(-)

> > 

> > diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c

> > index 15c2e55d2ed2..887a8102da9f 100644

> > --- a/fs/proc/proc_net.c

> > +++ b/fs/proc/proc_net.c

> > @@ -91,6 +91,7 @@ int bpf_iter_init_seq_net(void *priv_data, struct bpf_iter_aux_info *aux)

> >   #endif

> >   	return 0;

> >   }

> > +EXPORT_SYMBOL_GPL(bpf_iter_init_seq_net);

> 

> bpf_iter does not support modules for now as it is implemented before 

> module btf support. It needs some changes.

> For example, currently bpf_iter only caches/uses the vmlinux btf_id

> and module obj_id and module btf_id is not used.

> One example is ipv6 and bpf_iter is guarded with IS_BUILTIN(CONFIG_IPV6).

> 

> So you could (1) add btf_iter support module btf in this patch set, or

> (2). check IS_BUILTIN(CONFIG_UNIX). (2) might be easier and you can have

> a subsequent patch set to add module support for bpf_iter. But it is

> up to you.


I'll add IS_BUILTIN() check in the next spin and give a try to (1).
Thanks for review!