netdev - [PATCH RESEND bpf-next v4 00/11] Make check_func

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Date:   Mon, 21 Sep 2020 13:12:16 +0100
From:   Lorenz Bauer <lmb@...udflare.com>
To:     ast@...nel.org, daniel@...earbox.net
Cc:     bpf@...r.kernel.org, netdev@...r.kernel.org,
        Lorenz Bauer <lmb@...udflare.com>
Subject: [PATCH RESEND bpf-next v4 00/11] Make check_func_arg type checks table driven

I'm not sure why, but I missed sending the patchset to netdev@ last
week. I guess that is why it's slipped through the cracks.

Changes in v4:
- Output the desired type on BTF ID mismatch (Martin)

Changes in v3:
- Fix BTF_ID_LIST_SINGLE if BTF is disabled (Martin)
- Drop incorrect arg_btf_id in bpf_sk_storage.c (Martin)
- Check for arg_btf_id in check_func_proto (Martin)
- Drop incorrect PTR_TO_BTF_ID from fullsock_types (Martin)
- Introduce btf_seq_file_ids in bpf_trace.c to reduce duplication

Changes in v2:
- Make the series stand alone (Martin)
- Drop incorrect BTF_SET_START fix (Andrii)
- Only support a single BTF ID per argument (Martin)
- Introduce BTF_ID_LIST_SINGLE macro (Andrii)
- Skip check_ctx_reg iff register is NULL
- Change output of check_reg_type slightly, to avoid touching tests

Original cover letter:

Currently, check_func_arg has this pretty gnarly if statement that
compares the valid arg_type with the actualy reg_type. Sprinkled
in-between are checks for register_is_null, to short circuit these
tests if we're dealing with a nullable arg_type. There is also some
code for later bounds / access checking hidden away in there.

This series of patches refactors the function into something like this:

   if (reg_is_null && arg_type_is_nullable)
     skip type checking

   do type checking, including BTF validation

   do bounds / access checking

The type checking is now table driven, which makes it easy to extend
the acceptable types. Maybe more importantly, using a table makes it
easy to provide more helpful verifier output (see the last patch).

Lorenz Bauer (11):
  btf: make btf_set_contains take a const pointer
  bpf: check scalar or invalid register in check_helper_mem_access
  btf: Add BTF_ID_LIST_SINGLE macro
  bpf: allow specifying a BTF ID per argument in function protos
  bpf: make BTF pointer type checking generic
  bpf: make reference tracking generic
  bpf: make context access check generic
  bpf: set meta->raw_mode for pointers close to use
  bpf: check ARG_PTR_TO_SPINLOCK register type in check_func_arg
  bpf: hoist type checking for nullable arg types
  bpf: use a table to drive helper arg type checks

 include/linux/bpf.h            |  21 +-
 include/linux/btf_ids.h        |   8 +
 kernel/bpf/bpf_inode_storage.c |   8 +-
 kernel/bpf/btf.c               |  15 +-
 kernel/bpf/stackmap.c          |   5 +-
 kernel/bpf/verifier.c          | 338 ++++++++++++++++++---------------
 kernel/trace/bpf_trace.c       |  15 +-
 net/core/bpf_sk_storage.c      |   8 +-
 net/core/filter.c              |  31 +--
 net/ipv4/bpf_tcp_ca.c          |  19 +-
 tools/include/linux/btf_ids.h  |   8 +
 11 files changed, 239 insertions(+), 237 deletions(-)

-- 
2.25.1