BPF Archive on lore.kernel.org
 help / color / Atom feed
* [PATCH v2 bpf-next 0/3] bpf: Pointers beyond packet end.
@ 2020-11-11  3:12 Alexei Starovoitov
  2020-11-11  3:12 ` [PATCH v2 bpf-next 1/3] bpf: Support for pointers beyond pkt_end Alexei Starovoitov
                   ` (3 more replies)
  0 siblings, 4 replies; 13+ messages in thread
From: Alexei Starovoitov @ 2020-11-11  3:12 UTC (permalink / raw)
  To: davem; +Cc: daniel, netdev, bpf, kernel-team

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


^ permalink raw reply	[flat|nested] 13+ messages in thread

end of thread, back to index

Thread overview: 13+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-11-11  3:12 [PATCH v2 bpf-next 0/3] bpf: Pointers beyond packet end Alexei Starovoitov
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
2020-11-13  0:50 ` [PATCH v2 bpf-next 0/3] bpf: Pointers beyond packet end patchwork-bot+netdevbpf

BPF Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/bpf/0 bpf/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 bpf bpf/ https://lore.kernel.org/bpf \
		bpf@vger.kernel.org
	public-inbox-index bpf

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.bpf


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git