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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: davem@davemloft.net
Cc: daniel@iogearbox.net, netdev@vger.kernel.org,
	bpf@vger.kernel.org, kernel-team@fb.com
Subject: [PATCH v2 bpf-next 0/3] bpf: Pointers beyond packet end.
Date: Tue, 10 Nov 2020 19:12:10 -0800	[thread overview]
Message-ID: <20201111031213.25109-1-alexei.starovoitov@gmail.com> (raw)

From: Alexei Starovoitov <ast@kernel.org>

v1->v2:
- removed set-but-unused variable.
- added Jiri's Tested-by.

In some cases LLVM uses the knowledge that branch is taken to optimze the code
which causes the verifier to reject valid programs.
Teach the verifier to recognize that
r1 = skb->data;
r1 += 10;
r2 = skb->data_end;
if (r1 > r2) {
  here r1 points beyond packet_end and subsequent
  if (r1 > r2) // always evaluates to "true".
}

Alexei Starovoitov (3):
  bpf: Support for pointers beyond pkt_end.
  selftests/bpf: Add skb_pkt_end test
  selftests/bpf: Add asm tests for pkt vs pkt_end comparison.

 include/linux/bpf_verifier.h                  |   2 +-
 kernel/bpf/verifier.c                         | 129 +++++++++++++++---
 .../bpf/prog_tests/test_skb_pkt_end.c         |  41 ++++++
 .../testing/selftests/bpf/progs/skb_pkt_end.c |  54 ++++++++
 .../testing/selftests/bpf/verifier/ctx_skb.c  |  42 ++++++
 5 files changed, 245 insertions(+), 23 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/test_skb_pkt_end.c
 create mode 100644 tools/testing/selftests/bpf/progs/skb_pkt_end.c

-- 
2.24.1


             reply	other threads:[~2020-11-11  3:12 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-11  3:12 Alexei Starovoitov [this message]
2020-11-11  3:12 ` [PATCH v2 bpf-next 1/3] bpf: Support for pointers beyond pkt_end Alexei Starovoitov
2020-11-12 19:16   ` John Fastabend
2020-11-12 23:56     ` Daniel Borkmann
2020-11-13  0:09       ` Alexei Starovoitov
2020-11-13  0:50         ` Daniel Borkmann
2020-11-12 23:59     ` Alexei Starovoitov
2020-11-13  0:35       ` John Fastabend
2020-11-11  3:12 ` [PATCH v2 bpf-next 2/3] selftests/bpf: Add skb_pkt_end test Alexei Starovoitov
2020-11-12 19:19   ` John Fastabend
2020-11-11  3:12 ` [PATCH v2 bpf-next 3/3] selftests/bpf: Add asm tests for pkt vs pkt_end comparison Alexei Starovoitov
2020-11-12 19:24   ` John Fastabend
2021-01-20 20:51   ` Jiri Olsa
2020-11-13  0:50 ` [PATCH v2 bpf-next 0/3] bpf: Pointers beyond packet end patchwork-bot+netdevbpf

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