From patchwork Wed Aug 10 19:07:36 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin KaFai Lau X-Patchwork-Id: 12940912 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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 18B28C19F2A for ; Wed, 10 Aug 2022 19:10:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232389AbiHJTKP (ORCPT ); Wed, 10 Aug 2022 15:10:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42196 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232515AbiHJTKO (ORCPT ); Wed, 10 Aug 2022 15:10:14 -0400 Received: from mx0a-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0C2E931C for ; Wed, 10 Aug 2022 12:10:13 -0700 (PDT) Received: from pps.filterd (m0001303.ppops.net [127.0.0.1]) by m0001303.ppops.net (8.17.1.5/8.17.1.5) with ESMTP id 27AGuVHJ019126 for ; Wed, 10 Aug 2022 12:10:13 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=facebook; bh=ie6OTrk47jsy0MzsRPUtO1hyv5T5jiWL//SHBpvYCGk=; b=UfLhKUP/NN0dy9nmVzNh75W7+qgoCmutrvjvPfqXqjmuY7eQF0rtKVliDbnzQrdjTx4f a+sX7MxWQFHQplag2tgWXbs2pSkZyuDAXqlsD4HbqLIKzY7jSRhkYxdUfgXhAwqmiYmr FgUPaB00T99HzlWlIDIryLeTf0VKIIoAVsA= Received: from maileast.thefacebook.com ([163.114.130.16]) by m0001303.ppops.net (PPS) with ESMTPS id 3hvdb6k3k9-3 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 10 Aug 2022 12:10:13 -0700 Received: from twshared5413.23.frc3.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::c) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Wed, 10 Aug 2022 12:10:11 -0700 Received: by devbig933.frc1.facebook.com (Postfix, from userid 6611) id 7B98A7E74E1D; Wed, 10 Aug 2022 12:07:36 -0700 (PDT) From: Martin KaFai Lau To: , CC: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , David Miller , Eric Dumazet , Jakub Kicinski , , Paolo Abeni , Stanislav Fomichev Subject: [PATCH v3 bpf-next 02/15] bpf: net: Avoid sk_setsockopt() taking sk lock when called from bpf Date: Wed, 10 Aug 2022 12:07:36 -0700 Message-ID: <20220810190736.2693150-1-kafai@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220810190724.2692127-1-kafai@fb.com> References: <20220810190724.2692127-1-kafai@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: hhf1k559RUbUOg4-1lzoLdcjrOpGu7lU X-Proofpoint-GUID: hhf1k559RUbUOg4-1lzoLdcjrOpGu7lU X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-08-10_08,2022-08-10_01,2022-06-22_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Most of the code in bpf_setsockopt(SOL_SOCKET) are duplicated from the sk_setsockopt(). The number of supported optnames are increasing ever and so as the duplicated code. One issue in reusing sk_setsockopt() is that the bpf prog has already acquired the sk lock. This patch adds a has_current_bpf_ctx() to tell if the sk_setsockopt() is called from a bpf prog. The bpf prog calling bpf_setsockopt() is either running in_task() or in_serving_softirq(). Both cases have the current->bpf_ctx initialized. Thus, the has_current_bpf_ctx() only needs to test !!current->bpf_ctx. This patch also adds sockopt_{lock,release}_sock() helpers for sk_setsockopt() to use. These helpers will test has_current_bpf_ctx() before acquiring/releasing the lock. They are in EXPORT_SYMBOL for the ipv6 module to use in a latter patch. Note on the change in sock_setbindtodevice(). sockopt_lock_sock() is done in sock_setbindtodevice() instead of doing the lock_sock in sock_bindtoindex(..., lock_sk = true). Signed-off-by: Martin KaFai Lau --- include/linux/bpf.h | 14 ++++++++++++++ include/net/sock.h | 3 +++ net/core/sock.c | 30 +++++++++++++++++++++++++++--- 3 files changed, 44 insertions(+), 3 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index a627a02cf8ab..0a600b2013cc 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1966,6 +1966,16 @@ static inline bool unprivileged_ebpf_enabled(void) return !sysctl_unprivileged_bpf_disabled; } +/* Not all bpf prog type has the bpf_ctx. + * Only trampoline and cgroup-bpf have it. + * For the bpf prog type that has initialized the bpf_ctx, + * this function can be used to decide if a kernel function + * is called by a bpf program. + */ +static inline bool has_current_bpf_ctx(void) +{ + return !!current->bpf_ctx; +} #else /* !CONFIG_BPF_SYSCALL */ static inline struct bpf_prog *bpf_prog_get(u32 ufd) { @@ -2175,6 +2185,10 @@ static inline bool unprivileged_ebpf_enabled(void) return false; } +static inline bool has_current_bpf_ctx(void) +{ + return false; +} #endif /* CONFIG_BPF_SYSCALL */ void __bpf_free_used_btfs(struct bpf_prog_aux *aux, diff --git a/include/net/sock.h b/include/net/sock.h index a7273b289188..b2ff230860c6 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1721,6 +1721,9 @@ static inline void unlock_sock_fast(struct sock *sk, bool slow) } } +void sockopt_lock_sock(struct sock *sk); +void sockopt_release_sock(struct sock *sk); + /* Used by processes to "lock" a socket state, so that * interrupts and bottom half handlers won't change it * from under us. It essentially blocks any incoming diff --git a/net/core/sock.c b/net/core/sock.c index 20269c37ab3b..d3683228376f 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -703,7 +703,9 @@ static int sock_setbindtodevice(struct sock *sk, sockptr_t optval, int optlen) goto out; } - return sock_bindtoindex(sk, index, true); + sockopt_lock_sock(sk); + ret = sock_bindtoindex_locked(sk, index); + sockopt_release_sock(sk); out: #endif @@ -1036,6 +1038,28 @@ static int sock_reserve_memory(struct sock *sk, int bytes) return 0; } +void sockopt_lock_sock(struct sock *sk) +{ + /* When current->bpf_ctx is set, the setsockopt is called from + * a bpf prog. bpf has ensured the sk lock has been + * acquired before calling setsockopt(). + */ + if (has_current_bpf_ctx()) + return; + + lock_sock(sk); +} +EXPORT_SYMBOL(sockopt_lock_sock); + +void sockopt_release_sock(struct sock *sk) +{ + if (has_current_bpf_ctx()) + return; + + release_sock(sk); +} +EXPORT_SYMBOL(sockopt_release_sock); + /* * This is meant for all protocols to use and covers goings on * at the socket level. Everything here is generic. @@ -1067,7 +1091,7 @@ static int sk_setsockopt(struct sock *sk, int level, int optname, valbool = val ? 1 : 0; - lock_sock(sk); + sockopt_lock_sock(sk); switch (optname) { case SO_DEBUG: @@ -1496,7 +1520,7 @@ static int sk_setsockopt(struct sock *sk, int level, int optname, ret = -ENOPROTOOPT; break; } - release_sock(sk); + sockopt_release_sock(sk); return ret; }