From patchwork Wed Oct 18 06:03:12 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuyi Zhou X-Patchwork-Id: 13426391 X-Patchwork-Delegate: bpf@iogearbox.net Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 94A1C8F45 for ; Wed, 18 Oct 2023 06:03:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bytedance.com header.i=@bytedance.com header.b="lNlW4MHS" Received: from mail-pg1-x534.google.com (mail-pg1-x534.google.com [IPv6:2607:f8b0:4864:20::534]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12435FA for ; Tue, 17 Oct 2023 23:03:38 -0700 (PDT) Received: by mail-pg1-x534.google.com with SMTP id 41be03b00d2f7-5a9d8f4388bso2907063a12.3 for ; Tue, 17 Oct 2023 23:03:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1697609017; x=1698213817; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=BbIp3xjsMf+vYU1+9/Ac/+6x9YCK8BhSfh7PegmcPCk=; b=lNlW4MHStfBXSQ1ZYeV+XIS3QOZLzJkZOHDX+SGQImWJR7wjGSf+LEEKSXWalAzDgq pTspO64J2sy8MGGCQfunb4OU9Th+nqO2tKCiVZepLEuinRBm1hRJaRk+3jwVLGo5GCLQ o7ZhwvrYdBBzmIknzQxpxRAjd/EyvkzZwcohPREpsN73nDrgmzTkbAlJm2r0ENKyjmrR 0sBrxTdId0UKqNabUoYw4oOqYO5MXGAw9XPv15KLdJUjnWwX4NVJh93nb3Fq9ZTdxnpY P+YQHXbNtVJwCu367oMJCHfzwXVr8i21f1tKDYt5KrcOPMeSbSwAh/Kj68yg2oEfNZwh r5CQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1697609017; x=1698213817; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=BbIp3xjsMf+vYU1+9/Ac/+6x9YCK8BhSfh7PegmcPCk=; b=k/EdrKBmAVe6okooryS+CdXr2ej8jpBTO05/uTOBQNnbGhO9J8TRR5U0jTZgCxqXm0 NgAY4P4iePHVS0vKrnE6GW4HSaT5Eq+2Q4RNvlzkI1BBbQWtX1R6AQfqqXcVQ4NHo61e QoHBtPYks0X8wgeg0oJ7kWfN3QbNUZq/bYPdo0puC5EKP4zqfFfCJc4CXGIpoQQLyQpM w7isuNDbEvVNQMRJkX4hCp+0t8EJyhJ1wOwBy4yckNLXz8u+gHi6nMokbNMPydBjWpcu HDYlenIVY0wWL9sBHfSeDUgYv7KAStarBnxUxkiiH6p4YzMKhpOAEARuSC6wgKPS+3lD eH+Q== X-Gm-Message-State: AOJu0YzB5KbGJzKtmK/oK3KFZEyVngIjBC1K0o1aegevFea3SfycJLix ZpRtVtmFeSttSrLcb1kOpA2FLG38eJn8zGOwpu0= X-Google-Smtp-Source: AGHT+IFMdAqLCRZf5Wjki/UePWaDQXS6ZA3IGknhq+zJ6zAC4wWQO38tcJ+B2LN1oIJ3Nc21rJln/Q== X-Received: by 2002:a05:6a21:999c:b0:17a:f2ed:e921 with SMTP id ve28-20020a056a21999c00b0017af2ede921mr4145757pzb.55.1697609017344; Tue, 17 Oct 2023 23:03:37 -0700 (PDT) Received: from n37-019-243.byted.org ([180.184.51.40]) by smtp.gmail.com with ESMTPSA id b14-20020a17090acc0e00b00276cb03a0e9sm505782pju.46.2023.10.17.23.03.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Oct 2023 23:03:37 -0700 (PDT) From: Chuyi Zhou To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@kernel.org, tj@kernel.org, linux-kernel@vger.kernel.org, Chuyi Zhou Subject: [PATCH bpf-next v6 2/8] bpf: Introduce css_task open-coded iterator kfuncs Date: Wed, 18 Oct 2023 14:03:12 +0800 Message-Id: <20231018060318.105524-3-zhouchuyi@bytedance.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20231018060318.105524-1-zhouchuyi@bytedance.com> References: <20231018060318.105524-1-zhouchuyi@bytedance.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: bpf@iogearbox.net This patch adds kfuncs bpf_iter_css_task_{new,next,destroy} which allow creation and manipulation of struct bpf_iter_css_task in open-coded iterator style. These kfuncs actually wrapps css_task_iter_{start,next, end}. BPF programs can use these kfuncs through bpf_for_each macro for iteration of all tasks under a css. css_task_iter_*() would try to get the global spin-lock *css_set_lock*, so the bpf side has to be careful in where it allows to use this iter. Currently we only allow it in bpf_lsm and bpf iter-s. Signed-off-by: Chuyi Zhou Acked-by: Tejun Heo --- kernel/bpf/helpers.c | 3 + kernel/bpf/task_iter.c | 58 +++++++++++++++++++ kernel/bpf/verifier.c | 23 ++++++++ .../testing/selftests/bpf/bpf_experimental.h | 8 +++ 4 files changed, 92 insertions(+) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 61f51dee8448..c01441db9fd5 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2560,6 +2560,9 @@ BTF_ID_FLAGS(func, bpf_iter_num_destroy, KF_ITER_DESTROY) BTF_ID_FLAGS(func, bpf_iter_task_vma_new, KF_ITER_NEW | KF_RCU) BTF_ID_FLAGS(func, bpf_iter_task_vma_next, KF_ITER_NEXT | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_iter_task_vma_destroy, KF_ITER_DESTROY) +BTF_ID_FLAGS(func, bpf_iter_css_task_new, KF_ITER_NEW | KF_TRUSTED_ARGS) +BTF_ID_FLAGS(func, bpf_iter_css_task_next, KF_ITER_NEXT | KF_RET_NULL) +BTF_ID_FLAGS(func, bpf_iter_css_task_destroy, KF_ITER_DESTROY) BTF_ID_FLAGS(func, bpf_dynptr_adjust) BTF_ID_FLAGS(func, bpf_dynptr_is_null) BTF_ID_FLAGS(func, bpf_dynptr_is_rdonly) diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c index fef17628341f..e4126698cecf 100644 --- a/kernel/bpf/task_iter.c +++ b/kernel/bpf/task_iter.c @@ -894,6 +894,64 @@ __bpf_kfunc void bpf_iter_task_vma_destroy(struct bpf_iter_task_vma *it) __diag_pop(); +struct bpf_iter_css_task { + __u64 __opaque[1]; +} __attribute__((aligned(8))); + +struct bpf_iter_css_task_kern { + struct css_task_iter *css_it; +} __attribute__((aligned(8))); + +__diag_push(); +__diag_ignore_all("-Wmissing-prototypes", + "Global functions as their definitions will be in vmlinux BTF"); + +__bpf_kfunc int bpf_iter_css_task_new(struct bpf_iter_css_task *it, + struct cgroup_subsys_state *css, unsigned int flags) +{ + struct bpf_iter_css_task_kern *kit = (void *)it; + + BUILD_BUG_ON(sizeof(struct bpf_iter_css_task_kern) != sizeof(struct bpf_iter_css_task)); + BUILD_BUG_ON(__alignof__(struct bpf_iter_css_task_kern) != + __alignof__(struct bpf_iter_css_task)); + kit->css_it = NULL; + switch (flags) { + case CSS_TASK_ITER_PROCS | CSS_TASK_ITER_THREADED: + case CSS_TASK_ITER_PROCS: + case 0: + break; + default: + return -EINVAL; + } + + kit->css_it = bpf_mem_alloc(&bpf_global_ma, sizeof(struct css_task_iter)); + if (!kit->css_it) + return -ENOMEM; + css_task_iter_start(css, flags, kit->css_it); + return 0; +} + +__bpf_kfunc struct task_struct *bpf_iter_css_task_next(struct bpf_iter_css_task *it) +{ + struct bpf_iter_css_task_kern *kit = (void *)it; + + if (!kit->css_it) + return NULL; + return css_task_iter_next(kit->css_it); +} + +__bpf_kfunc void bpf_iter_css_task_destroy(struct bpf_iter_css_task *it) +{ + struct bpf_iter_css_task_kern *kit = (void *)it; + + if (!kit->css_it) + return; + css_task_iter_end(kit->css_it); + bpf_mem_free(&bpf_global_ma, kit->css_it); +} + +__diag_pop(); + DEFINE_PER_CPU(struct mmap_unlock_irq_work, mmap_unlock_work); static void do_mmap_read_unlock(struct irq_work *entry) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index bb58987e4844..974713185269 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -10472,6 +10472,7 @@ enum special_kfunc_type { KF_bpf_percpu_obj_new_impl, KF_bpf_percpu_obj_drop_impl, KF_bpf_throw, + KF_bpf_iter_css_task_new, }; BTF_SET_START(special_kfunc_set) @@ -10495,6 +10496,7 @@ BTF_ID(func, bpf_dynptr_clone) BTF_ID(func, bpf_percpu_obj_new_impl) BTF_ID(func, bpf_percpu_obj_drop_impl) BTF_ID(func, bpf_throw) +BTF_ID(func, bpf_iter_css_task_new) BTF_SET_END(special_kfunc_set) BTF_ID_LIST(special_kfunc_list) @@ -10520,6 +10522,7 @@ BTF_ID(func, bpf_dynptr_clone) BTF_ID(func, bpf_percpu_obj_new_impl) BTF_ID(func, bpf_percpu_obj_drop_impl) BTF_ID(func, bpf_throw) +BTF_ID(func, bpf_iter_css_task_new) static bool is_kfunc_ret_null(struct bpf_kfunc_call_arg_meta *meta) { @@ -11050,6 +11053,20 @@ static int process_kf_arg_ptr_to_rbtree_node(struct bpf_verifier_env *env, &meta->arg_rbtree_root.field); } +static bool check_css_task_iter_allowlist(struct bpf_verifier_env *env) +{ + enum bpf_prog_type prog_type = resolve_prog_type(env->prog); + + switch (prog_type) { + case BPF_PROG_TYPE_LSM: + return true; + case BPF_TRACE_ITER: + return env->prog->aux->sleepable; + default: + return false; + } +} + static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_arg_meta *meta, int insn_idx) { @@ -11300,6 +11317,12 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ break; } case KF_ARG_PTR_TO_ITER: + if (meta->func_id == special_kfunc_list[KF_bpf_iter_css_task_new]) { + if (!check_css_task_iter_allowlist(env)) { + verbose(env, "css_task_iter is only allowed in bpf_lsm and bpf iter-s\n"); + return -EINVAL; + } + } ret = process_iter_arg(env, regno, insn_idx, meta); if (ret < 0) return ret; diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h index 2c8cb3f61529..6792ed2b45d7 100644 --- a/tools/testing/selftests/bpf/bpf_experimental.h +++ b/tools/testing/selftests/bpf/bpf_experimental.h @@ -458,4 +458,12 @@ extern void bpf_throw(u64 cookie) __ksym; __bpf_assert_op(LHS, <=, END, value, false); \ }) +struct bpf_iter_css_task; +struct cgroup_subsys_state; +extern int bpf_iter_css_task_new(struct bpf_iter_css_task *it, + struct cgroup_subsys_state *css, unsigned int flags) __weak __ksym; +extern struct task_struct *bpf_iter_css_task_next(struct bpf_iter_css_task *it) __weak __ksym; +extern void bpf_iter_css_task_destroy(struct bpf_iter_css_task *it) __weak __ksym; + + #endif