From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 70831C5479D for ; Sat, 7 Jan 2023 02:54:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235330AbjAGCyo (ORCPT ); Fri, 6 Jan 2023 21:54:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60438 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229809AbjAGCyn (ORCPT ); Fri, 6 Jan 2023 21:54:43 -0500 Received: from mail-pf1-x449.google.com (mail-pf1-x449.google.com [IPv6:2607:f8b0:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6555B8B53A for ; Fri, 6 Jan 2023 18:54:41 -0800 (PST) Received: by mail-pf1-x449.google.com with SMTP id bq10-20020a056a000e0a00b00581221976c0so1618664pfb.10 for ; Fri, 06 Jan 2023 18:54:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=/LXD7bWn6Jkwh9hHWJBLtYnysPLbu62uMIUKDSw+zHg=; b=D/axEx4FkjtSzhj6GtMgJ/eJNW2W8y+wGrdJ6WK+JKRibRRQcNB02GD5Ej+HMaYzOn I4r8jetP7aQCigvNTyA+nvW63VqQ2V6lagidpSk2Wc6g3eMvIVBCfLScXdMjhdGhYnS2 gZdq4p+zvacBigitPU1lyIDbtuDurtbuBWboWKzVSJylU00HTdVPoEFrfKombEw7cYgp fkl7HePlLnEugAAkQqbvJFIge9bxGIJIlNcDBXdTB4qpZZSDOGPLVcMmn64hFW/w8vgf 8UdkiTCNLip4UgwFTTGJyht9/eGWnzVCemsh9yUucwUUbZONP3ieq5KhQWJigpJdk5M1 VWag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=/LXD7bWn6Jkwh9hHWJBLtYnysPLbu62uMIUKDSw+zHg=; b=yjw/ps2W1B0IkagG0ppGkS5HGEUtI8HEvMaURX5h0WSjrLlRdntVP6oFqWQnLNgVYF no8t2XoNShtSPQjZ4TEyL7RRP/6xPaWgG9fWTlZsU0PzAspkhygMvnqu8PUzVPYPBr18 cRfT7tpvNVJ8Ll45OhDVr4CSkIlB/YldvngwjajXhVkWTI/gAB4enjQa+NmLV39i9m4X WLdK2P6R9Z/BKz//XRWr0RvCRDiEBe9+DBVI75ArT+nBCC2sj+vZ2Hnas2ZcBeBnla3O Gzsj3TZDaZVvPxKxqCCpMSWb5igshN8EPp1GlDLt4Gdw+2tGoGFaK2xyRBxX//3y/o28 wh1w== X-Gm-Message-State: AFqh2kq9P+Ayn3GL4sfa5C7YELhtPvB4AcAl4ZiCezC2jyftNnXCVVNE gHPF0PfMQ9kcqClNWwnJNyVazbnAdoXelJsCjMDWBHm49S3Hc43npq/m0t+D2skzZg1lI/ZdhGk 8cE+h+vhXpWBJ+Dk0Rs39Ky0iWYy48lyxWkDon7br9Su+bahxbz1L+VkoAajQ X-Google-Smtp-Source: AMrXdXuGpkSqOris5d+pibbC28QA9/oo3sbz/IB0DzZeTVqkNYBWIuBFM7QwHx+JujDwlaS/nrNsSF5P8JLU X-Received: from connoro.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:a99]) (user=connoro job=sendgmr) by 2002:a05:6a00:440b:b0:583:860:7a30 with SMTP id br11-20020a056a00440b00b0058308607a30mr906809pfb.1.1673060080726; Fri, 06 Jan 2023 18:54:40 -0800 (PST) Date: Sat, 7 Jan 2023 02:53:31 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog Message-ID: <20230107025331.3240536-1-connoro@google.com> Subject: [PATCH bpf-next v3] bpf: btf: limit logging of ignored BTF mismatches From: "Connor O'Brien" To: bpf@vger.kernel.org Cc: Martin KaFai Lau , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , linux-kernel@vger.kernel.org, "Connor O'Brien" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Enabling CONFIG_MODULE_ALLOW_BTF_MISMATCH is an indication that BTF mismatches are expected and module loading should proceed anyway. Logging with pr_warn() on every one of these "benign" mismatches creates unnecessary noise when many such modules are loaded. Instead, handle this case with a single log warning that BTF info may be unavailable. Mismatches also result in calls to __btf_verifier_log() via __btf_verifier_log_type() or btf_verifier_log_member(), adding several additional lines of logging per mismatched module. Add checks to these paths to skip logging for module BTF mismatches in the "allow mismatch" case. All existing logging behavior is preserved in the default CONFIG_MODULE_ALLOW_BTF_MISMATCH=n case. Signed-off-by: Connor O'Brien Acked-by: Yonghong Song --- v3: - fix commenting style - reuse existing "log->level == BPF_LOG_KERNEL" check for kernel BTF v2: - Use pr_warn_once instead of skipping logging entirely - Also skip btf verifier logs for ignored mismatches v1: https://lore.kernel.org/bpf/20221109024155.2810410-1-connoro@google.com/ --- kernel/bpf/btf.c | 38 +++++++++++++++++++++++++++----------- 1 file changed, 27 insertions(+), 11 deletions(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index f7dd8af06413..67eee2d83dc8 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -1397,12 +1397,18 @@ __printf(4, 5) static void __btf_verifier_log_type(struct btf_verifier_env *env, if (!bpf_verifier_log_needed(log)) return; - /* btf verifier prints all types it is processing via - * btf_verifier_log_type(..., fmt = NULL). - * Skip those prints for in-kernel BTF verification. - */ - if (log->level == BPF_LOG_KERNEL && !fmt) - return; + if (log->level == BPF_LOG_KERNEL) { + /* btf verifier prints all types it is processing via + * btf_verifier_log_type(..., fmt = NULL). + * Skip those prints for in-kernel BTF verification. + */ + if (!fmt) + return; + + /* Skip logging when loading module BTF with mismatches permitted */ + if (env->btf->base_btf && IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH)) + return; + } __btf_verifier_log(log, "[%u] %s %s%s", env->log_type_id, @@ -1441,8 +1447,15 @@ static void btf_verifier_log_member(struct btf_verifier_env *env, if (!bpf_verifier_log_needed(log)) return; - if (log->level == BPF_LOG_KERNEL && !fmt) - return; + if (log->level == BPF_LOG_KERNEL) { + if (!fmt) + return; + + /* Skip logging when loading module BTF with mismatches permitted */ + if (env->btf->base_btf && IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH)) + return; + } + /* The CHECK_META phase already did a btf dump. * * If member is logged again, it must hit an error in @@ -7260,11 +7273,14 @@ static int btf_module_notify(struct notifier_block *nb, unsigned long op, } btf = btf_parse_module(mod->name, mod->btf_data, mod->btf_data_size); if (IS_ERR(btf)) { - pr_warn("failed to validate module [%s] BTF: %ld\n", - mod->name, PTR_ERR(btf)); kfree(btf_mod); - if (!IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH)) + if (!IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH)) { + pr_warn("failed to validate module [%s] BTF: %ld\n", + mod->name, PTR_ERR(btf)); err = PTR_ERR(btf); + } else { + pr_warn_once("Kernel module BTF mismatch detected, BTF debug info may be unavailable for some modules\n"); + } goto out; } err = btf_alloc_id(btf); -- 2.39.0.314.g84b9a713c41-goog