From: Daniel Borkmann <daniel@iogearbox.net>
To: Edward Cree <ecree@solarflare.com>, davem@davemloft.net
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Alexei Starovoitov <ast@fb.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
iovisor-dev <iovisor-dev@lists.iovisor.org>
Subject: Re: [PATCH v5 net-next 00/12] bpf: rewrite value tracking in verifier
Date: Tue, 08 Aug 2017 02:46:16 +0200 [thread overview]
Message-ID: <598909D8.5060202@iogearbox.net> (raw)
In-Reply-To: <ad840039-8d4a-b2a9-b2eb-a8f079926b53@solarflare.com>
On 08/07/2017 04:21 PM, Edward Cree wrote:
> This series simplifies alignment tracking, generalises bounds tracking and
> fixes some bounds-tracking bugs in the BPF verifier. Pointer arithmetic on
> packet pointers, stack pointers, map value pointers and context pointers has
> been unified, and bounds on these pointers are only checked when the pointer
> is dereferenced.
> Operations on pointers which destroy all relation to the original pointer
> (such as multiplies and shifts) are disallowed if !env->allow_ptr_leaks,
> otherwise they convert the pointer to an unknown scalar and feed it to the
> normal scalar arithmetic handling.
> Pointer types have been unified with the corresponding adjusted-pointer types
> where those existed (e.g. PTR_TO_MAP_VALUE[_ADJ] or FRAME_PTR vs
> PTR_TO_STACK); similarly, CONST_IMM and UNKNOWN_VALUE have been unified into
> SCALAR_VALUE.
> Pointer types (except CONST_PTR_TO_MAP, PTR_TO_MAP_VALUE_OR_NULL and
> PTR_TO_PACKET_END, which do not allow arithmetic) have a 'fixed offset' and
> a 'variable offset'; the former is used when e.g. adding an immediate or a
> known-constant register, as long as it does not overflow. Otherwise the
> latter is used, and any operation creating a new variable offset creates a
> new 'id' (and, for PTR_TO_PACKET, clears the 'range').
> SCALAR_VALUEs use the 'variable offset' fields to track the range of possible
> values; the 'fixed offset' should never be set on a scalar.
Been testing and reviewing the series over the last several days, looks
reasonable to me as far as I can tell. Thanks for all the hard work on
unifying this, Edward!
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
next prev parent reply other threads:[~2017-08-08 0:46 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-07 14:21 [PATCH v5 net-next 00/12] bpf: rewrite value tracking in verifier Edward Cree
2017-08-07 14:26 ` [PATCH v5 net-next 01/12] bpf/verifier: rework value tracking Edward Cree
2017-08-07 14:26 ` [PATCH v5 net-next 02/12] bpf/verifier: track signed and unsigned min/max values Edward Cree
2017-08-07 14:26 ` [PATCH v5 net-next 03/12] bpf/verifier: more concise register state logs for constant var_off Edward Cree
2017-08-07 14:27 ` [PATCH v5 net-next 04/12] selftests/bpf: change test_verifier expectations Edward Cree
2017-08-07 14:27 ` [PATCH v5 net-next 05/12] selftests/bpf: rewrite test_align Edward Cree
2017-08-07 14:28 ` [PATCH v5 net-next 06/12] selftests/bpf: add a test to test_align Edward Cree
2017-08-07 14:28 ` [PATCH v5 net-next 07/12] selftests/bpf: add test for bogus operations on pointers Edward Cree
2017-08-07 14:29 ` [PATCH v5 net-next 08/12] selftests/bpf: don't try to access past MAX_PACKET_OFF in test_verifier Edward Cree
2017-08-07 14:29 ` [PATCH v5 net-next 09/12] selftests/bpf: add tests for subtraction & negative numbers Edward Cree
2017-08-07 14:29 ` [PATCH v5 net-next 10/12] selftests/bpf: variable offset negative tests Edward Cree
2017-08-07 14:30 ` [PATCH v5 net-next 11/12] Documentation: describe the new eBPF verifier value tracking behaviour Edward Cree
2017-08-07 14:30 ` [PATCH v5 net-next 12/12] bpf/verifier: increase complexity limit to 128k Edward Cree
2017-08-08 0:46 ` Daniel Borkmann [this message]
2017-08-09 0:51 ` [PATCH v5 net-next 00/12] bpf: rewrite value tracking in verifier David Miller
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