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 A8371C433EF for ; Fri, 14 Jan 2022 05:45:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236351AbiANFpB convert rfc822-to-8bit (ORCPT ); Fri, 14 Jan 2022 00:45:01 -0500 Received: from szxga01-in.huawei.com ([45.249.212.187]:35838 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234904AbiANFpB (ORCPT ); Fri, 14 Jan 2022 00:45:01 -0500 Received: from kwepemi500008.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4JZqxG1QK2zccWc; Fri, 14 Jan 2022 13:44:18 +0800 (CST) Received: from kwepeml500003.china.huawei.com (7.221.188.182) by kwepemi500008.china.huawei.com (7.221.188.139) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Fri, 14 Jan 2022 13:44:58 +0800 Received: from dggpeml500011.china.huawei.com (7.185.36.84) by kwepeml500003.china.huawei.com (7.221.188.182) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Fri, 14 Jan 2022 13:44:58 +0800 Received: from dggpeml500011.china.huawei.com ([7.185.36.84]) by dggpeml500011.china.huawei.com ([7.185.36.84]) with mapi id 15.01.2308.020; Fri, 14 Jan 2022 13:44:58 +0800 From: "zhudi (E)" To: Jakub Sitnicki CC: "ast@kernel.org" , "davem@davemloft.net" , "daniel@iogearbox.net" , "andrii@kernel.org" , "kafai@fb.com" , "songliubraving@fb.com" , "yhs@fb.com" , "john.fastabend@gmail.com" , "kpsingh@kernel.org" , "bpf@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "Luzhihao (luzhihao, Euler)" , "Chenxiang (EulerOS)" Subject: Re: [PATCH bpf-next v5 1/2] bpf: support BPF_PROG_QUERY for progs attached to sockmap Thread-Topic: [PATCH bpf-next v5 1/2] bpf: support BPF_PROG_QUERY for progs attached to sockmap Thread-Index: AdgJAVS91cwWMrx3QDm+6rM/XIXS/w== Date: Fri, 14 Jan 2022 05:44:57 +0000 Message-ID: <3abe6e9f2e1a408f887b1dd31862f7b1@huawei.com> Accept-Language: zh-CN, en-US Content-Language: zh-CN X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.136.114.155] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org > On Thu, Jan 13, 2022 at 10:00 AM CET, Di Zhu wrote: > > Right now there is no way to query whether BPF programs are > > attached to a sockmap or not. > > > > we can use the standard interface in libbpf to query, such as: > > bpf_prog_query(mapFd, BPF_SK_SKB_STREAM_PARSER, 0, NULL, ...); > > the mapFd is the fd of sockmap. > > > > Signed-off-by: Di Zhu > > Acked-by: Yonghong Song > > --- > > include/linux/bpf.h | 9 +++++ > > kernel/bpf/syscall.c | 5 +++ > > net/core/sock_map.c | 78 > ++++++++++++++++++++++++++++++++++++++++---- > > 3 files changed, 85 insertions(+), 7 deletions(-) > > > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > > index 6e947cd91152..c4ca14c9f838 100644 > > --- a/include/linux/bpf.h > > +++ b/include/linux/bpf.h > > @@ -2071,6 +2071,9 @@ int bpf_prog_test_run_syscall(struct bpf_prog > *prog, > > int sock_map_get_from_fd(const union bpf_attr *attr, struct bpf_prog > *prog); > > int sock_map_prog_detach(const union bpf_attr *attr, enum bpf_prog_type > ptype); > > int sock_map_update_elem_sys(struct bpf_map *map, void *key, void *value, > u64 flags); ....... > > +int sock_map_bpf_prog_query(const union bpf_attr *attr, > > + union bpf_attr __user *uattr) > > +{ > > + __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids); > > + u32 prog_cnt = 0, flags = 0, ufd = attr->target_fd; > > + struct bpf_prog **pprog; > > + struct bpf_prog *prog; > > + struct bpf_map *map; > > + struct fd f; > > + u32 id = 0; > > + int ret; > > + > > + if (attr->query.query_flags) > > + return -EINVAL; > > + > > + f = fdget(ufd); > > + map = __bpf_map_get(f); > > + if (IS_ERR(map)) > > + return PTR_ERR(map); > > + > > + rcu_read_lock(); > > + > > + ret = sock_map_prog_lookup(map, &pprog, attr->query.attach_type); > > + if (ret) > > + goto end; > > + > > + prog = *pprog; > > + prog_cnt = !prog ? 0 : 1; > > + > > + if (!attr->query.prog_cnt || !prog_ids || !prog_cnt) > > + goto end; > > + > > + id = prog->aux->id; > > ^ This looks like a concurrent read/write. > > Would wrap with READ_ONCE() and corresponding WRITE_ONCE() in > bpf_prog_free_id(). See [1] for rationale. > > [1] > https://github.com/google/kernel-sanitizers/blob/master/other/READ_WRITE_O > NCE.md Thanks for your advice, I will modify this code. > > + > > + /* we do not hold the refcnt, the bpf prog may be released > > + * asynchronously and the id would be set to 0. > > + */ > > + if (id == 0) > > + prog_cnt = 0; > > + > > +end: > > + rcu_read_unlock(); > > + > > + if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)) || > > + (id != 0 && copy_to_user(prog_ids, &id, sizeof(u32))) || > > + copy_to_user(&uattr->query.prog_cnt, &prog_cnt, sizeof(prog_cnt))) > > + ret = -EFAULT; > > + > > + fdput(f); > > + return ret; > > +} > > + > > static void sock_map_unlink(struct sock *sk, struct sk_psock_link *link) > > { > > switch (link->map->map_type) {