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  1. 17 May, 2023 4 commits
    • Yonghong Song's avatar
      selftests/bpf: Fix s390 sock_field test failure · de58ef41
      Yonghong Song authored 
      llvm patch [1] enabled cross-function optimization for func arguments
(ArgumentPromotion) at -O2 level. And this caused s390 sock_fields
test failure ([2]). The failure is gone right now as patch [1] was
reverted in [3]. But it is possible that patch [3] will be reverted
again and then the test failure in [2] will show up again. So it is
desirable to fix the failure regardless.

The following is an analysis why sock_field test fails with
llvm patch [1].

The main problem is in
  static __noinline bool sk_dst_port__load_word(struct bpf_sock *sk)
  {
        __u32 *word = (__u32 *)&sk->dst_port;
        return word[0] == bpf_htons(0xcafe);
  }
  static __noinline bool sk_dst_port__load_half(struct bpf_sock *sk)
  {
        __u16 *half = (__u16 *)&sk->dst_port;
        return half[0] == bpf_htons(0xcafe);
  }
  ...
  int read_sk_dst_port(struct __sk_buff *skb)
  {
	...
        sk = skb->sk;
	...
        if (!sk_dst_port__load_word(sk))
                RET_LOG();
        if (!sk_dst_port__load_half(sk))
                RET_LOG();
	...
  }

Through some cross-function optimization by ArgumentPromotion
optimization, the compiler does:
  static __noinline bool sk_dst_port__load_word(__u32 word_val)
  {
        return word_val == bpf_htons(0xcafe);
  }
  static __noinline bool sk_dst_port__load_half(__u16 half_val)
  {
        return half_val == bpf_htons(0xcafe);
  }
  ...
  int read_sk_dst_port(struct __sk_buff *skb)
  {
        ...
        sk = skb->sk;
        ...
        __u32 *word = (__u32 *)&sk->dst_port;
        __u32 word_val = word[0];
        ...
        if (!sk_dst_port__load_word(word_val))
                RET_LOG();

        __u16 half_val = word_val >> 16;
        if (!sk_dst_port__load_half(half_val))
                RET_LOG();
        ...
  }

In current uapi bpf.h, we have
  struct bpf_sock {
	...
        __be16 dst_port;        /* network byte order */
        __u16 :16;              /* zero padding */
	...
  };
But the old kernel (e.g., 5.6) we have
  struct bpf_sock {
	...
	__u32 dst_port;         /* network byte order */
	...
  };

So for backward compatability reason, 4-byte load of
dst_port is converted to 2-byte load internally.
Specifically, 'word_val = word[0]' is replaced by 2-byte load
by the verifier and this caused the trouble for later
sk_dst_port__load_half() where half_val becomes 0.

Typical usr program won't have such a code pattern tiggering
the above bug, so let us fix the test failure with source
code change. Adding an empty asm volatile statement seems
enough to prevent undesired transformation.

  [1] https://reviews.llvm.org/D148269
  [2] https://lore.kernel.org/bpf/e7f2c5e8-a50c-198d-8f95-388165f1e4fd@meta.com/
  [3] https://reviews.llvm.org/rG141be5c062ecf22bd287afffd310e8ac4711444aTested-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20230516214945.1013578-1-yhs@fb.comSigned-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      de58ef41
    • Andrii Nakryiko's avatar
      selftests/bpf: improve netcnt test robustness · 24a86d83
      Andrii Nakryiko authored 
      Change netcnt to demand at least 10K packets, as we frequently see some
stray packet arriving during the test in BPF CI. It seems more important
to make sure we haven't lost any packet than enforcing exact number of
packets.

Cc: Stanislav Fomichev <sdf@google.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarStanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230515204833.2832000-1-andrii@kernel.orgSigned-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      24a86d83
    • Jakub Kicinski's avatar
      Revert "net: Remove low_thresh in ip defrag" · e7480a44
      Jakub Kicinski authored 
      This reverts commit b2cbac9b.

We have multiple reports of obvious breakage from this patch.
Reported-by: default avatarIdo Schimmel <idosch@idosch.org>
Link: https://lore.kernel.org/all/ZGIRWjNcfqI8yY8W@shredder/
Link: https://lore.kernel.org/all/CADJHv_sDK=0RrMA2FTZQV5fw7UQ+qY=HG21Wu5qb0V9vvx5w6A@mail.gmail.com/
Reported-by: syzbot+a5e719ac7c268e414c95@syzkaller.appspotmail.com
Reported-by: syzbot+a03fd670838d927d9cd8@syzkaller.appspotmail.com
Fixes: b2cbac9b ("net: Remove low_thresh in ip defrag")
Link: https://lore.kernel.org/r/20230517034112.1261835-1-kuba@kernel.orgSigned-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      e7480a44
    • Jakub Kicinski's avatar
      Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next · a0e35a64
      Jakub Kicinski authored 
      Daniel Borkmann says:

====================
pull-request: bpf-next 2023-05-16

We've added 57 non-merge commits during the last 19 day(s) which contain
a total of 63 files changed, 3293 insertions(+), 690 deletions(-).

The main changes are:

1) Add precision propagation to verifier for subprogs and callbacks,
   from Andrii Nakryiko.

2) Improve BPF's {g,s}setsockopt() handling with wrong option lengths,
   from Stanislav Fomichev.

3) Utilize pahole v1.25 for the kernel's BTF generation to filter out
   inconsistent function prototypes, from Alan Maguire.

4) Various dyn-pointer verifier improvements to relax restrictions,
   from Daniel Rosenberg.

5) Add a new bpf_task_under_cgroup() kfunc for designated task,
   from Feng Zhou.

6) Unblock tests for arm64 BPF CI after ftrace supporting direct call,
   from Florent Revest.

7) Add XDP hint kfunc metadata for RX hash/timestamp for igc,
   from Jesper Dangaard Brouer.

8) Add several new dyn-pointer kfuncs to ease their usability,
   from Joanne Koong.

9) Add in-depth LRU internals description and dot function graph,
   from Joe Stringer.

10) Fix KCSAN report on bpf_lru_list when accessing node->ref,
    from Martin KaFai Lau.

11) Only dump unprivileged_bpf_disabled log warning upon write,
    from Kui-Feng Lee.

12) Extend test_progs to directly passing allow/denylist file,
    from Stephen Veiss.

13) Fix BPF trampoline memleak upon failure attaching to fentry,
    from Yafang Shao.

14) Fix emitting struct bpf_tcp_sock type in vmlinux BTF,
    from Yonghong Song.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (57 commits)
  bpf: Fix memleak due to fentry attach failure
  bpf: Remove bpf trampoline selector
  bpf, arm64: Support struct arguments in the BPF trampoline
  bpftool: JIT limited misreported as negative value on aarch64
  bpf: fix calculation of subseq_idx during precision backtracking
  bpf: Remove anonymous union in bpf_kfunc_call_arg_meta
  bpf: Document EFAULT changes for sockopt
  selftests/bpf: Correctly handle optlen > 4096
  selftests/bpf: Update EFAULT {g,s}etsockopt selftests
  bpf: Don't EFAULT for {g,s}setsockopt with wrong optlen
  libbpf: fix offsetof() and container_of() to work with CO-RE
  bpf: Address KCSAN report on bpf_lru_list
  bpf: Add --skip_encoding_btf_inconsistent_proto, --btf_gen_optimized to pahole flags for v1.25
  selftests/bpf: Accept mem from dynptr in helper funcs
  bpf: verifier: Accept dynptr mem as mem in helpers
  selftests/bpf: Check overflow in optional buffer
  selftests/bpf: Test allowing NULL buffer in dynptr slice
  bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)
  selftests/bpf: Add testcase for bpf_task_under_cgroup
  bpf: Add bpf_task_under_cgroup() kfunc
  ...
====================

Link: https://lore.kernel.org/r/20230515225603.27027-1-daniel@iogearbox.netSigned-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      a0e35a64
  3. 16 May, 2023 7 commits
  5. 15 May, 2023 20 commits
  7. 14 May, 2023 1 commit
    • Martin KaFai Lau's avatar
      Merge branch 'bpf: Don't EFAULT for {g,s}setsockopt with wrong optlen' · 79b3604d
      Martin KaFai Lau authored 
      Stanislav Fomichev says:

====================
optval larger than PAGE_SIZE leads to EFAULT if the BPF program
isn't careful enough. This is often overlooked and might break
completely unrelated socket options. Instead of EFAULT,
let's ignore BPF program buffer changes. See the first patch for
more info.

In addition, clearly document this corner case and reset optlen
in our selftests (in case somebody copy-pastes from them).

v6:
- no changes; resending due to screwing up v5 series with the unrelated
  patch

v5:
- goto in the selftest (Martin)
- set IP_TOS to zero to avoid endianness complications (Martin)

v4:
- ignore retval as well when optlen > PAGE_SIZE (Martin)

v3:
- don't hard-code PAGE_SIZE (Martin)
- reset orig_optlen in getsockopt when kernel part succeeds (Martin)
====================
Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
      79b3604d
  9. 13 May, 2023 8 commits
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