From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-02.galae.net (smtpout-02.galae.net [185.246.84.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 179543783C1; Tue, 4 Aug 2026 17:45:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.246.84.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785865551; cv=none; b=rms9kIkzoIM/v11IIWmcszd8OXRLdBWhtl21x/rMKXdC5/84zkwLhz5IzU1D8mRBUE6LmiHyEeKTevyYwzQxwEPvZSPagh4Xc8+Q0nAaJ6i8lj0q6UVVF+lbhSH9VhiYhyRFi69RdLN5ZeslpP5mtetIcIEqOUqjBTepYXeXeIA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785865551; c=relaxed/simple; bh=TQMcsOCloSAd5xFahG0H7HtjQDcXNjVSroQlYGm19r0=; h=From:Subject:Date:Message-Id:MIME-Version:Content-Type:To:Cc; b=caRFQ9W1ae2nAjn7MBeRtYEidbHsqzfmpog8oWsD5r4YwdBqoEiS5vDADaiA3KRpQo/VDEL8YGcxST9bbobrggZAXUEBN0/dL9aWj6YhnkIiwA2vMuibaRnY08sATFQ6Nazb0Td/Y0YPaRPVAOGAR0VtlDaHP/HSweM4R80Fx/w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=1BbidVjd; arc=none smtp.client-ip=185.246.84.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="1BbidVjd" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-02.galae.net (Postfix) with ESMTPS id 5FE871A13EE; Tue, 4 Aug 2026 17:45:43 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 24E496029E; Tue, 4 Aug 2026 17:45:43 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 0E56C11C33447; Tue, 4 Aug 2026 19:45:35 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1785865541; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding; bh=FC7RLm/BkIpau9DjmjsOAD4rPdrWRZHkY3bsZYPi5tw=; b=1BbidVjd4y4t3o7SkLJEU8jWX8juavfHM3pviMwAhQS/JKdj5frDTGh42LB7FKV6cfWX4e 2gM8h7jETcC/b4Og7waghUNYBVQzSNM9jwGnEs61/JkxtqxvTw1903M3pt9Rzebtj/mIHs LWOchBARzleRSiaTG/AwsBkhJnrz/ehqOJ1YLpc3MP7SNqiEbyEVPSo/VE8sA90gSpBor/ U16MBPt0mNT700bZPA2ZpHhXExA+fiKJMDOxYKgcEVsgH2AagcGbLjVukC7k+tC4FW5eGE a2VeNZnQnajrSUJVt3+WO2u6tGVP3L5xeVnEhhaBmzXTr7oFG+QAZGQ+BspjAg== From: =?utf-8?q?Alexis_Lothor=C3=A9_=28eBPF_Foundation=29?= Subject: [PATCH bpf-next v6 0/9] bpf: add support for KASAN checks in JITed programs Date: Tue, 04 Aug 2026 19:45:31 +0200 Message-Id: <20260804-kasan-v6-0-549ef845f491@bootlin.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit X-B4-Tracking: v=1; b=H4sIAAAAAAAC/2XPTW7DIBAF4KtErEvFDBhwVr1HlQW/DWoLkbGsR JHvXopqJZWXozffG82d1DClUMnxcCdTWFJNJbdBvhyIO5v8EWjybSbIUDJAST9NNZlG56WOUji vLGm7lynEdO0978ReIs3hOpNTS86pzmW69QML9Lx3CeB/XQtQRsEMmgNyphHebCnzV8qvrnz3j gUfrsnNYXOOSRkkquiN3jv+cIrB5nhz1rPR2lGg13LvxLPTmxPN+cGBUsZqRLV3w7MbNzf8/ue kMFEHESD8d+u6/gA7iZmhhgEAAA== X-Change-ID: 20260126-kasan-fcd68f64cd7b To: Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Kumar Kartikeya Dwivedi , Song Liu , Yonghong Song , Jiri Olsa , Thomas Gleixner , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Shuah Khan , Ingo Molnar , Andrey Konovalov Cc: ebpf@linuxfoundation.org, Bastien Curutchet , Thomas Petazzoni , bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, =?utf-8?q?Alexis_Lothor=C3=A9_=28eBPF_Foundation=29?= , Ihor Solodrai X-Mailer: b4 0.15.2 X-Last-TLS-Session-Version: TLSv1.3 Hello, this is v6 of the series aiming to bring basic support for KASAN checks to BPF JITed programs. This new revision takes a step back on stack accessing insn tracking, as the previous attempt was fragile and error-prone, it brings back a simpler tracking, at the cost of some unecessary checks being inserted. While at it, I took this time a look at how many accesses are being instrumented, and how many of those are "wrongly" instrumented (because they access stack), and I got those rough numbers on the whole selftests set: - total: 451997 checks inserted - checks added on stack access (checking reg == BPF_REG_FP, not precise, but gives a rough idea): 21786 So that makes ~5% of "over-instrumented" accesses Original cover letter: "Traditional" KASAN allows to spot memory management mistakes by reserving a fraction of memory as "shadow memory" that will map to the rest of the memory and allow its monitoring. Each memory-accessing instruction is then instrumented at build time to call some ASAN check function, that will analyze the corresponding bits in shadow memory, and if it detects the access as invalid, trigger a detailed report. The goal of this series is to replicate this mechanism for BPF programs when they are being JITed into native instructions: that's then the JIT compiler that is in charge of inserting calls to the corresponding kasan checks, when a program is being loaded into the kernel. This task involves: - identifying at program load time the instructions performing memory accesses - identifying those accesses properties (size ? read or write ?) to define the relevant kasan check function to call - just before the identified instructions: - perform the basic context saving (ie: saving registers) - inserting a call to the relevant kasan check function - restore context - whenever the instrumented program executes, if it performs an invalid access, it triggers a kasan report identical to those instrumented on kernel side at build time. The series comes with new selftests programs that generate a wide variety of kasan reports: those need the kernel to be running with kasan_multi_shot enabled. As discussed in [1], this series is based on some choices and assumptions: - it focuses on x86_64 for now, and so only on KASAN_GENERIC - not all memory accessing BPF instructions are being instrumented: - it discards instructions accessing BPF program stack (already monitored by page guards) - it discards possibly faulting instructions, like BPF_PROBE_MEM or BPF_PROBE_ATOMIC insns --- Changes in v6: - dropped instruction original offset tracking - when patching instructions, track former non_stack_access flag by passing original insn to adjust_insn_aux_data - drop unecessary dep on CONFIG_KASAN in Kconfig - fold patch adding the emit_kasan_helper into the patch actually calling it, to avoid an unused static function warning - move stack access check out of emit_kasan_check - replace hardcoded ip value by a computed value - add OoB testing - add fix commit to make cmdline_contains stricter - Link to v5: https://patch.msgid.link/20260709-kasan-v5-0-1c64af8e4e1e@bootlin.com Changes in v5: - fixed a few instruction offset for generated fixups - fix insn marking for single insn patches - enforce more checks in tests - skip tests if kasan_multi_shot isn't enabled - Link to v4: https://patch.msgid.link/20260708-kasan-v4-0-d5c177ab8227@bootlin.com Changes in v4: - fix insn_offs_in_patch leakage in bpf_convert_ctx_access - handle BPF_ATOMIC in is_mem_insn - correctly mark fixup instructions if a single insn is generated - clarify new kconfig (Andrey) and drop VMAP_STACK dep - refactor BPF_FETCH atomic handling in JIT loop - make kernel log reading resilient to unrelated, interleaved logs in the selftests - make new test kfuncs depend on BPF_JIT_KASAN rather than KASAN_GENERIC - Link to v3: https://patch.msgid.link/20260701-kasan-v3-0-bd09bb942d86@bootlin.com Changes in v3: - Do not insert KASAN instrumentation when dealing with cBPF - Fix stack-accessing insn tracking for verifier patches, as original instruction location in the generated patch may vary - drop cBPF support for stack-accessing insn marking - make sure to flag correctly memory access if different verifier states involve different memory types (eg: stack in one path, non-stack in another path) - refactor BPF_ST handling in x86 JIT compiler - improve tests coverage (cover instrumentation for a few patches emitted by the verifier) - Link to v2: https://patch.msgid.link/20260604-kasan-v2-0-c066e627fda8@bootlin.com Changes in v2: - declare asan functions as extern in JIT compiler rather than exposing them in kasan header - invert stack-accessing instructions marking to make sure not to skip instructions that could end up accessing to-be-checked memory - fix stack accesses marking when verifier patches instructions - add best effort marking for cBPF - add missing call depth accounting in jited instrumentation - skip unused registers in kasan instrumentation save/restore - remove faulty stack align in kasan instrumentation - drop commit skipping some jit-related tests - cover missing instructions: BPF_ST and atomics - completely rework tests: directly tune shadow memory, increase coverage, do not consume kernel logs - Link to v1: https://patch.msgid.link/20260413-kasan-v1-0-1a5831230821@bootlin.com To: Alexei Starovoitov To: Daniel Borkmann To: John Fastabend To: Andrii Nakryiko To: Martin KaFai Lau To: Eduard Zingerman To: Kumar Kartikeya Dwivedi To: Song Liu To: Yonghong Song To: Jiri Olsa To: Thomas Gleixner To: Borislav Petkov To: Dave Hansen To: x86@kernel.org To: "H. Peter Anvin" To: Shuah Khan To: Ingo Molnar To: Andrey Konovalov Cc: ebpf@linuxfoundation.org Cc: Bastien Curutchet Cc: Thomas Petazzoni Cc: bpf@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-kselftest@vger.kernel.org --- Alexis Lothoré (eBPF Foundation) (9): bpf: mark instructions accessing program stack bpf: add BPF_JIT_KASAN for KASAN instrumentation of JITed programs bpf, x86: refactor BPF_ST management in do_jit bpf, x86: emit KASAN checks in x86 JITed programs bpf, x86: enable KASAN for JITed programs on x86 selftests/bpf: make cmdline_contains stricter selftests/bpf: add helpers for KASAN in JIT testing selftests/bpf: move bpf_jit_harden helper into testing_helpers selftests/bpf: add tests to validate KASAN on JIT programs arch/x86/Kconfig | 1 + arch/x86/net/bpf_jit_comp.c | 283 ++++++++++--- include/linux/bpf_verifier.h | 2 + kernel/bpf/Kconfig | 17 + kernel/bpf/fixups.c | 45 +- kernel/bpf/verifier.c | 9 + .../selftests/bpf/prog_tests/bpf_insn_array.c | 44 +- tools/testing/selftests/bpf/prog_tests/kasan.c | 454 ++++++++++++++++++++ tools/testing/selftests/bpf/progs/kasan.c | 462 +++++++++++++++++++++ tools/testing/selftests/bpf/progs/kasan_harden.c | 41 ++ .../testing/selftests/bpf/test_kmods/bpf_testmod.c | 55 +++ tools/testing/selftests/bpf/testing_helpers.c | 32 ++ tools/testing/selftests/bpf/testing_helpers.h | 1 + tools/testing/selftests/bpf/unpriv_helpers.c | 21 +- tools/testing/selftests/bpf/unpriv_helpers.h | 2 + 15 files changed, 1369 insertions(+), 100 deletions(-) --- base-commit: 5fb2b9636c7043f415a12e3336f2bf6983c9e93a change-id: 20260126-kasan-fcd68f64cd7b Best regards, -- Alexis Lothoré (eBPF Foundation)