From patchwork Wed Dec 20 21:39:58 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxim Mikityanskiy X-Patchwork-Id: 13500495 Received: from mail-ed1-f51.google.com (mail-ed1-f51.google.com [209.85.208.51]) (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 43434495E2; Wed, 20 Dec 2023 21:40:26 +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="YIX4x5/p" Received: by mail-ed1-f51.google.com with SMTP id 4fb4d7f45d1cf-54f4f7e88feso157063a12.3; Wed, 20 Dec 2023 13:40:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1703108425; x=1703713225; 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=MzuubNkvst/9i8BFChAgxHMD9ThadUV92R9A6HcZzrE=; b=YIX4x5/p2cmHw83mm/O6yyGLKp6gNDmuqwznR5PYtNhFSS1CzBOE1BZ5bfdIwsevUR K0/8IgjyykVEFy30vnQ97Ztna7R+9ZSEylyMLG0PNf/hHr2gT7IZIHkduFf2SJVzRFh2 pcU23sDGEcFEkOVwKIVoxTe1mrt5zzHVE+RGGBbxeCpu/5IXUVUTNo8BI3T+xaGaRZgx 5P6V/TeguPVJkalBITSh1DMlPfZo3vA1xr2u2MnApJHz/fIgdipWFkrB7OnJXh/LENvy 5KGeIINXGZPpRIN6g573Y0SQd9M6xg3c9pbnvdGXRG3lCUx+x3GXuYNRuYdd2NLyYuLz rj1g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703108425; x=1703713225; 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=MzuubNkvst/9i8BFChAgxHMD9ThadUV92R9A6HcZzrE=; b=jMqt0hLDZgOWwEX+AvRovVTla31hb3jQhTh+EfN+8E6Ll3NtLsKb6nvjARCLfWjctJ t/1uJ+HfFhjCyimNBbw09X2tjcIcaIBHkHS/BoE4LlagPJxLdnlbmEHmOJ1i0kGJIlCA fidn2E+IguDKJcvq/zykZaDnM8z5msjK7leryqwhP7iO8pWiMlY93nzPP7ssJF6GXVJ3 4xo20VFY+Q0BZA/4rWToyhn0/6rFO7zTMTqB0eJpXfE0tePtb9tLgrtt7UhBEn1KlDQK nxJ+L0sc/MWRv0CRYop8LFyibzQ6dL5LWeLiyDtk2AEFkEbaqMa8biKPK7QfIsiOQsaj 19DQ== X-Gm-Message-State: AOJu0Yw7rYOy+znShyJU0pxeyf+9Lf5BVX8M4L0rMgnQIEn9SO7XHq8V ctQqw1+l1cZdr1qTnUQxsAI= X-Google-Smtp-Source: AGHT+IFgt5CHbyFocEJTyy1xKdfEag+/QY5YQzYz1KGsLP+apqD8OMxmN5u2n9D9p0Z6o71u/+sX5w== X-Received: by 2002:a50:cd51:0:b0:553:5f4:7d81 with SMTP id d17-20020a50cd51000000b0055305f47d81mr4684928edj.61.1703108425239; Wed, 20 Dec 2023 13:40:25 -0800 (PST) Received: from localhost ([185.220.101.166]) by smtp.gmail.com with ESMTPSA id a5-20020aa7cf05000000b005537e39745csm296817edy.47.2023.12.20.13.40.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Dec 2023 13:40:24 -0800 (PST) From: Maxim Mikityanskiy To: Eduard Zingerman , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko 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 00/15] Improvements for tracking scalars in the BPF verifier Date: Wed, 20 Dec 2023 23:39:58 +0200 Message-ID: <20231220214013.3327288-1-maxtram95@gmail.com> X-Mailer: git-send-email 2.42.1 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net 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%) 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 | 2 +- kernel/bpf/verifier.c | 160 +++++- .../bpf/progs/verifier_direct_packet_access.c | 2 +- .../selftests/bpf/progs/verifier_loops1.c | 24 + .../selftests/bpf/progs/verifier_spill_fill.c | 529 +++++++++++++++++- .../testing/selftests/bpf/verifier/precise.c | 6 +- 6 files changed, 677 insertions(+), 46 deletions(-)