From patchwork Wed Nov 4 16:44:48 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: KP Singh X-Patchwork-Id: 11881559 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E6A79C388F9 for ; Wed, 4 Nov 2020 16:45:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 89763206DB for ; Wed, 4 Nov 2020 16:45:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="j+kzqPsw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731260AbgKDQpE (ORCPT ); Wed, 4 Nov 2020 11:45:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731252AbgKDQpD (ORCPT ); Wed, 4 Nov 2020 11:45:03 -0500 Received: from mail-ed1-x544.google.com (mail-ed1-x544.google.com [IPv6:2a00:1450:4864:20::544]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2272BC0613D3 for ; Wed, 4 Nov 2020 08:45:03 -0800 (PST) Received: by mail-ed1-x544.google.com with SMTP id a71so17764966edf.9 for ; Wed, 04 Nov 2020 08:45:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=4FZ5EX5ob47PENxRCM6uj8lA8NDTk22XRLqBPr/+ZVE=; b=j+kzqPsw7LqQJpM35MVcE4bc+PhaDF2/Otd7tEbdcgCd+g+p/+iqO/H6Z9/0g7ZmGp c9pxNcPFamaXD158T5XiG8ZLjXWUh+w6fgRFCEF55W5kkf1ENsKgzCOQ1IJuNQ4IQzic gnqGbWPpEEAaWwTn0zagDsNNQWo0B2ApmAWUw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=4FZ5EX5ob47PENxRCM6uj8lA8NDTk22XRLqBPr/+ZVE=; b=nE140JLOjAljMg0ZQJ+pf8v+A68rtJG0Yp/LZdAx+RoUN80MQ8WDI5wyab65k1yoiU udmGyhzkc1igw7YmVdvzllOFxpdBwwmsx21vaYb5tHt5CCCjFCoL0Kl8HS0hmuo4qh+q W2FchbYtBoRa2fUrR61i3Wf/P56Cit7EBfWe576fi4XHnAZBpzgxPu47yRN5DKgciMxK k69cYVY7DRqWFEgX1CSQePoMvkDZ9HuU7vcOwweJoG4xOEs3IiLtbqIXu5UdxWtYzih9 mR3dAwTQa9ZIg3fJrGAWeigqNiRN3eozTs7+M0G0Sf7HVFKAaQMKeblYExduCo3ZFbvO gW0A== X-Gm-Message-State: AOAM532UJMgZt/ZTf9vQvc/BAK915V8IYGMYSNqh93PatS5j6GfNIS3i 1aR/5qr4Ny38RBjmbHDgFf+lWA== X-Google-Smtp-Source: ABdhPJzX/EZbh0s/Xz2rf65CLqPUrdEQmavgTbvLL1JSohOnR1ZDfiX0/klZhnPLLElAANw2GFp5Zg== X-Received: by 2002:a05:6402:4cb:: with SMTP id n11mr27576683edw.296.1604508301836; Wed, 04 Nov 2020 08:45:01 -0800 (PST) Received: from kpsingh.zrh.corp.google.com ([81.6.44.51]) by smtp.gmail.com with ESMTPSA id g20sm1283551ejz.88.2020.11.04.08.45.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Nov 2020 08:45:01 -0800 (PST) From: KP Singh To: linux-kernel@vger.kernel.org, bpf@vger.kernel.org Cc: Song Liu , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Paul Turner , Jann Horn , Hao Luo Subject: [PATCH bpf-next v3 4/9] bpf: Implement get_current_task_btf and RET_PTR_TO_BTF_ID Date: Wed, 4 Nov 2020 17:44:48 +0100 Message-Id: <20201104164453.74390-5-kpsingh@chromium.org> X-Mailer: git-send-email 2.29.1.341.ge80a0c044ae-goog In-Reply-To: <20201104164453.74390-1-kpsingh@chromium.org> References: <20201104164453.74390-1-kpsingh@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net From: KP Singh The currently available bpf_get_current_task returns an unsigned integer which can be used along with BPF_CORE_READ to read data from the task_struct but still cannot be used as an input argument to a helper that accepts an ARG_PTR_TO_BTF_ID of type task_struct. In order to implement this helper a new return type, RET_PTR_TO_BTF_ID, is added. This is similar to RET_PTR_TO_BTF_ID_OR_NULL but does not require checking the nullness of returned pointer. Acked-by: Song Liu Signed-off-by: KP Singh --- include/linux/bpf.h | 1 + include/uapi/linux/bpf.h | 9 +++++++++ kernel/bpf/verifier.c | 7 +++++-- kernel/trace/bpf_trace.c | 16 ++++++++++++++++ tools/include/uapi/linux/bpf.h | 9 +++++++++ 5 files changed, 40 insertions(+), 2 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 2fffd30e13ac..73d5381a5d5c 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -310,6 +310,7 @@ enum bpf_return_type { RET_PTR_TO_BTF_ID_OR_NULL, /* returns a pointer to a btf_id or NULL */ RET_PTR_TO_MEM_OR_BTF_ID_OR_NULL, /* returns a pointer to a valid memory or a btf_id or NULL */ RET_PTR_TO_MEM_OR_BTF_ID, /* returns a pointer to a valid memory or a btf_id */ + RET_PTR_TO_BTF_ID, /* returns a pointer to a btf_id */ }; /* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index f4037b2161a6..9879d6793e90 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3779,6 +3779,14 @@ union bpf_attr { * 0 on success. * * **-ENOENT** if the bpf_local_storage cannot be found. + * + * struct task_struct *bpf_get_current_task_btf(void) + * Description + * Return a BTF pointer to the "current" task. + * This pointer can also be used in helpers that accept an + * *ARG_PTR_TO_BTF_ID* of type *task_struct*. + * Return + * Pointer to the current task. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3939,6 +3947,7 @@ union bpf_attr { FN(redirect_peer), \ FN(task_storage_get), \ FN(task_storage_delete), \ + FN(get_current_task_btf), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index b0790876694f..314018e8fc12 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5186,11 +5186,14 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn PTR_TO_BTF_ID : PTR_TO_BTF_ID_OR_NULL; regs[BPF_REG_0].btf_id = meta.ret_btf_id; } - } else if (fn->ret_type == RET_PTR_TO_BTF_ID_OR_NULL) { + } else if (fn->ret_type == RET_PTR_TO_BTF_ID_OR_NULL || + fn->ret_type == RET_PTR_TO_BTF_ID) { int ret_btf_id; mark_reg_known_zero(env, regs, BPF_REG_0); - regs[BPF_REG_0].type = PTR_TO_BTF_ID_OR_NULL; + regs[BPF_REG_0].type = fn->ret_type == RET_PTR_TO_BTF_ID ? + PTR_TO_BTF_ID : + PTR_TO_BTF_ID_OR_NULL; ret_btf_id = *fn->ret_btf_id; if (ret_btf_id == 0) { verbose(env, "invalid return type %d of func %s#%d\n", diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 4517c8b66518..e4515b0f62a8 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1022,6 +1022,20 @@ const struct bpf_func_proto bpf_get_current_task_proto = { .ret_type = RET_INTEGER, }; +BPF_CALL_0(bpf_get_current_task_btf) +{ + return (unsigned long) current; +} + +BTF_ID_LIST_SINGLE(bpf_get_current_btf_ids, struct, task_struct) + +static const struct bpf_func_proto bpf_get_current_task_btf_proto = { + .func = bpf_get_current_task_btf, + .gpl_only = true, + .ret_type = RET_PTR_TO_BTF_ID, + .ret_btf_id = &bpf_get_current_btf_ids[0], +}; + BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx) { struct bpf_array *array = container_of(map, struct bpf_array, map); @@ -1265,6 +1279,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_get_current_pid_tgid_proto; case BPF_FUNC_get_current_task: return &bpf_get_current_task_proto; + case BPF_FUNC_get_current_task_btf: + return &bpf_get_current_task_btf_proto; case BPF_FUNC_get_current_uid_gid: return &bpf_get_current_uid_gid_proto; case BPF_FUNC_get_current_comm: diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index f4037b2161a6..9879d6793e90 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -3779,6 +3779,14 @@ union bpf_attr { * 0 on success. * * **-ENOENT** if the bpf_local_storage cannot be found. + * + * struct task_struct *bpf_get_current_task_btf(void) + * Description + * Return a BTF pointer to the "current" task. + * This pointer can also be used in helpers that accept an + * *ARG_PTR_TO_BTF_ID* of type *task_struct*. + * Return + * Pointer to the current task. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3939,6 +3947,7 @@ union bpf_attr { FN(redirect_peer), \ FN(task_storage_get), \ FN(task_storage_delete), \ + FN(get_current_task_btf), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper