From patchwork Mon Jan 8 20:51:54 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxim Mikityanskiy X-Patchwork-Id: 13513966 Received: from mail-ej1-f52.google.com (mail-ej1-f52.google.com [209.85.218.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 64E5955E46; Mon, 8 Jan 2024 20:52:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="JqsaWkrU" Received: by mail-ej1-f52.google.com with SMTP id a640c23a62f3a-a2ac304e526so120871666b.0; Mon, 08 Jan 2024 12:52:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1704747142; x=1705351942; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=pt5ZBMAmBsmSRV69wcHOG+kyXrXealjLznmp8t+4vXs=; b=JqsaWkrU8WEgInv5qAVCSNDP2gREWCF7JMvEhcrZd1A/vU9k9Ke5yuuAZTbW+PZVJf VonW9nTlzi5ja3NQ77BOv8hHNOThTiS4nFNEfSldyJzHd1Gn6j1HY0WN5k1zr6DsW1ZM qtgLxMaOIsAE47wGAlNV64Ix63FDLPOtsM7H1Y0dgJXJ5KMsAhyfzjQqzjpsF39y3YZF 4RET/jatxb415cZVOUebbPmaqFK1wtQW6tSUPfyhRJj+kWLcBAaglZOKQnC1Aq4lGMBJ OsawXOTYzFVbkgFdUwJJq/IaB8cqlYJ96NJeM4ezf1D8w0LQ+8VtpBrswgs4oiYYLtvt f3Uw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1704747142; x=1705351942; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=pt5ZBMAmBsmSRV69wcHOG+kyXrXealjLznmp8t+4vXs=; b=PaUITy8RYeGLsmHGBiW/yPLSt93f0dly9LLyJ2kuoGui4O10RbtMe/zwBLJLP6NizJ /7yzDcuL1QzDF6EmF/GTAiR49pW+y5I26vvIpqCGzTpouUyp3Z2Zq6zSt9w0UHE9WbZG voGvyOkIrHiGQRyZ8vsQ6pW871hvQNb9Q9JhSmuZeIA/nhJBEgUNkZ/TAHleHLwXPUFP Kz1/2GZs3Frp8McFS3moaTya90tVx3AHFaUbnL8bVwUADdeAgAbgar+/Bo5+UYwu084p 1WQdJZ5vAl7xRLOqq1vMRpbl/azXkLkwx+IM0CGTIPtTIRHVq/YuYSThdBVUlLlU2xXq 6Ucg== X-Gm-Message-State: AOJu0Yy5CnbRbJ7ncr4DUvWeUWCJHmVG6m3++i16EiWPGVEOGFpZVnt7 kCAUfrO6gRtAXwIYmR9ehLE= X-Google-Smtp-Source: AGHT+IFqN6+gjU6/FmZMQH3eFTlQMUeABxDMRt7hv7vBNJphODGfuL+eU8WN5ynT1iAAytnaXuSitw== X-Received: by 2002:a17:907:500f:b0:a2b:1a20:36b7 with SMTP id fw15-20020a170907500f00b00a2b1a2036b7mr11421ejc.49.1704747142437; Mon, 08 Jan 2024 12:52:22 -0800 (PST) Received: from localhost ([185.220.101.66]) by smtp.gmail.com with ESMTPSA id gl16-20020a170906e0d000b00a28bf7969cdsm240864ejb.180.2024.01.08.12.52.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Jan 2024 12:52:22 -0800 (PST) From: Maxim Mikityanskiy To: Eduard Zingerman , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Shung-Hsi Yu Cc: John Fastabend , Martin KaFai Lau , Song Liu , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Mykola Lysenko , Shuah Khan , "David S. Miller" , Jakub Kicinski , Jesper Dangaard Brouer , bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, netdev@vger.kernel.org, Maxim Mikityanskiy Subject: [PATCH bpf-next v2 00/15] Improvements for tracking scalars in the BPF verifier Date: Mon, 8 Jan 2024 22:51:54 +0200 Message-ID: <20240108205209.838365-1-maxtram95@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Maxim Mikityanskiy The goal of this series is to extend the verifier's capabilities of tracking scalars when they are spilled to stack, especially when the spill or fill is narrowing. It also contains a fix by Eduard for infinite loop detection and a state pruning optimization by Eduard that compensates for a verification complexity regression introduced by tracking unbounded scalars. These improvements reduce the surface of false rejections that I saw while working on Cilium codebase. Patch 1 (Maxim): Fix for an existing test, it will matter later in the series. Patches 2-3 (Eduard): Fixes for false rejections in infinite loop detection that happen in the selftests when my patches are applied. Patches 4-5 (Maxim): Fix the inconsistency of find_equal_scalars that was possible if 32-bit spills were made. Patches 6-11 (Maxim): Support the case when boundary checks are first performed after the register was spilled to the stack. Patches 12-13 (Maxim): Support narrowing fills. Patches 14-15 (Eduard): Optimization for state pruning in stacksafe() to mitigate the verification complexity regression. veristat -e file,prog,states -f '!states_diff<50' -f '!states_pct<10' -f '!states_a<10' -f '!states_b<10' -C ... * Without patch 14: File Program States (A) States (B) States (DIFF) -------------------- ------------ ---------- ---------- ---------------- bpf_xdp.o tail_lb_ipv6 3877 2936 -941 (-24.27%) pyperf180.bpf.o on_event 8422 10456 +2034 (+24.15%) pyperf600.bpf.o on_event 22259 37319 +15060 (+67.66%) pyperf600_iter.bpf.o on_event 400 540 +140 (+35.00%) strobemeta.bpf.o on_event 4702 13435 +8733 (+185.73%) * With patch 14: File Program States (A) States (B) States (DIFF) -------------------- ------------ ---------- ---------- -------------- bpf_xdp.o tail_lb_ipv6 3877 2937 -940 (-24.25%) pyperf600_iter.bpf.o on_event 400 500 +100 (+25.00%) v2 changes: Fixed comments in patch 1, moved endianness checks to header files in patch 12 where possible, added Eduard's ACKs. Eduard Zingerman (4): bpf: make infinite loop detection in is_state_visited() exact selftests/bpf: check if imprecise stack spills confuse infinite loop detection bpf: Optimize state pruning for spilled scalars selftests/bpf: states pruning checks for scalar vs STACK_{MISC,ZERO} Maxim Mikityanskiy (11): selftests/bpf: Fix the u64_offset_to_skb_data test bpf: Make bpf_for_each_spilled_reg consider narrow spills selftests/bpf: Add a test case for 32-bit spill tracking bpf: Add the assign_scalar_id_before_mov function bpf: Add the get_reg_width function bpf: Assign ID to scalars on spill selftests/bpf: Test assigning ID to scalars on spill bpf: Track spilled unbounded scalars selftests/bpf: Test tracking spilled unbounded scalars bpf: Preserve boundaries and track scalars on narrowing fill selftests/bpf: Add test cases for narrowing fill include/linux/bpf_verifier.h | 4 +- include/linux/filter.h | 12 + kernel/bpf/verifier.c | 155 ++++- .../bpf/progs/verifier_direct_packet_access.c | 2 +- .../selftests/bpf/progs/verifier_loops1.c | 24 + .../selftests/bpf/progs/verifier_spill_fill.c | 533 +++++++++++++++++- .../testing/selftests/bpf/verifier/precise.c | 6 +- 7 files changed, 685 insertions(+), 51 deletions(-)