netdev - [PATCH v4 bpf 0/5] Fix bpf_tcp_sock and bpf_sk_fullsock issue related to bpf_sk

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Date:   Tue, 12 Mar 2019 10:23:01 -0700
From:   Martin KaFai Lau <kafai@...com>
To:     <netdev@...r.kernel.org>
CC:     Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>, <kernel-team@...com>,
        Lorenz Bauer <lmb@...udflare.com>
Subject: [PATCH v4 bpf 0/5] Fix bpf_tcp_sock and bpf_sk_fullsock issue related to bpf_sk_release

This set addresses issue about accessing invalid
ptr returned from bpf_tcp_sock() and bpf_sk_fullsock()
after bpf_sk_release().

v4:
- Tried the one "id" approach.  It does not work well and the reason is in
  the Patch 1 commit message.
- Rename refcount_id to ref_obj_id.
- With ref_obj_id, resetting reg->id to 0 is fine in mark_ptr_or_null_reg()
  because ref_obj_id is passed to release_reference() instead of reg->id.
- Also reset reg->ref_obj_id in mark_ptr_or_null_reg() when is_null == true
- sk_to_full_sk() is removed from bpf_sk_fullsock() and bpf_tcp_sock().
- bpf_get_listener_sock() is added to do sk_to_full_sk() in Patch 2.
- If tp is from bpf_tcp_sock(sk) and sk is a refcounted ptr,
  bpf_sk_release(tp) is also allowed.

v3:
- reset reg->refcount_id for the is_null case in mark_ptr_or_null_reg()

v2:
- Remove refcount_id arg from release_reference() because
  id == refcount_id
- Add a WARN_ON_ONCE to mark_ptr_or_null_regs() to catch
  an internal verifier bug.

Martin KaFai Lau (5):
  bpf: Fix bpf_tcp_sock and bpf_sk_fullsock issue related to
    bpf_sk_release
  bpf: Add bpf_get_listener_sock(struct bpf_sock *sk) helper
  bpf: Sync bpf.h to tools/
  bpf: Test ref release issue in bpf_tcp_sock and bpf_sk_fullsock
  bpf: Add an example for bpf_get_listener_sock

 include/linux/bpf.h                           |   1 -
 include/linux/bpf_verifier.h                  |  40 +++++
 include/uapi/linux/bpf.h                      |  11 +-
 kernel/bpf/verifier.c                         | 131 ++++++++------
 net/core/filter.c                             |  27 ++-
 tools/include/uapi/linux/bpf.h                |  11 +-
 tools/testing/selftests/bpf/bpf_helpers.h     |   2 +
 .../bpf/progs/test_sock_fields_kern.c         |  88 +++++++--
 .../testing/selftests/bpf/test_sock_fields.c  | 134 +++++++++++---
 .../selftests/bpf/verifier/ref_tracking.c     | 168 ++++++++++++++++++
 tools/testing/selftests/bpf/verifier/sock.c   |   4 +-
 11 files changed, 506 insertions(+), 111 deletions(-)

-- 
2.17.1