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 2CCDDC25B0D for ; Wed, 10 Aug 2022 13:44:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232724AbiHJNoe convert rfc822-to-8bit (ORCPT ); Wed, 10 Aug 2022 09:44:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54248 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229680AbiHJNod (ORCPT ); Wed, 10 Aug 2022 09:44:33 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D27876714A; Wed, 10 Aug 2022 06:44:31 -0700 (PDT) Received: from fraeml715-chm.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4M2rh82TQLz67wDW; Wed, 10 Aug 2022 21:41:44 +0800 (CST) Received: from fraeml714-chm.china.huawei.com (10.206.15.33) by fraeml715-chm.china.huawei.com (10.206.15.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Wed, 10 Aug 2022 15:44:29 +0200 Received: from fraeml714-chm.china.huawei.com ([10.206.15.33]) by fraeml714-chm.china.huawei.com ([10.206.15.33]) with mapi id 15.01.2375.024; Wed, 10 Aug 2022 15:44:29 +0200 From: Roberto Sassu To: Jarkko Sakkinen CC: "ast@kernel.org" , "daniel@iogearbox.net" , "andrii@kernel.org" , "martin.lau@linux.dev" , "song@kernel.org" , "yhs@fb.com" , "john.fastabend@gmail.com" , "kpsingh@kernel.org" , "sdf@google.com" , "haoluo@google.com" , "jolsa@kernel.org" , "corbet@lwn.net" , "dhowells@redhat.com" , "rostedt@goodmis.org" , "mingo@redhat.com" , "paul@paul-moore.com" , "jmorris@namei.org" , "serge@hallyn.com" , "shuah@kernel.org" , "bpf@vger.kernel.org" , "linux-doc@vger.kernel.org" , "keyrings@vger.kernel.org" , "linux-security-module@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Benjamin Tissoires , Yosry Ahmed Subject: RE: [PATCH v9 01/10] btf: Add a new kfunc flag which allows to mark a function to be sleepable Thread-Topic: [PATCH v9 01/10] btf: Add a new kfunc flag which allows to mark a function to be sleepable Thread-Index: AQHYq/aDa3kCDLsk5EK6T80CaXl/sK2mqA6AgAF8nfA= Date: Wed, 10 Aug 2022 13:44:28 +0000 Message-ID: References: <20220809134603.1769279-1-roberto.sassu@huawei.com> <20220809134603.1769279-2-roberto.sassu@huawei.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.45.144.193] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-CFilter-Loop: Reflected Precedence: bulk List-ID: > From: Jarkko Sakkinen [mailto:jarkko@kernel.org] > Sent: Tuesday, August 9, 2022 6:55 PM > On Tue, Aug 09, 2022 at 03:45:54PM +0200, Roberto Sassu wrote: > > From: Benjamin Tissoires > > > > From: Benjamin Tissoires > > > > This allows to declare a kfunc as sleepable and prevents its use in > > a non sleepable program. > > Nit: "Declare a kfunc as sleepable and prevent its use in a > non-sleepable program." > > It's missing the part *how* the patch accomplishes its goals. I will add: If an eBPF program is going to call a kfunc declared as sleepable, eBPF will look at the eBPF program flags. If BPF_F_SLEEPABLE is not set, execution of that program is denied. Roberto > > Signed-off-by: Benjamin Tissoires > > Co-developed-by: Yosry Ahmed > > Signed-off-by: Yosry Ahmed > > Signed-off-by: Hao Luo > > --- > > Documentation/bpf/kfuncs.rst | 6 ++++++ > > include/linux/btf.h | 1 + > > kernel/bpf/btf.c | 9 +++++++++ > > 3 files changed, 16 insertions(+) > > > > diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst > > index c0b7dae6dbf5..c8b21de1c772 100644 > > --- a/Documentation/bpf/kfuncs.rst > > +++ b/Documentation/bpf/kfuncs.rst > > @@ -146,6 +146,12 @@ that operate (change some property, perform some > operation) on an object that > > was obtained using an acquire kfunc. Such kfuncs need an unchanged pointer > to > > ensure the integrity of the operation being performed on the expected object. > > > > +2.4.6 KF_SLEEPABLE flag > > +----------------------- > > + > > +The KF_SLEEPABLE flag is used for kfuncs that may sleep. Such kfuncs can > only > > +be called by sleepable BPF programs (BPF_F_SLEEPABLE). > > + > > 2.5 Registering the kfuncs > > -------------------------- > > > > diff --git a/include/linux/btf.h b/include/linux/btf.h > > index cdb376d53238..976cbdd2981f 100644 > > --- a/include/linux/btf.h > > +++ b/include/linux/btf.h > > @@ -49,6 +49,7 @@ > > * for this case. > > */ > > #define KF_TRUSTED_ARGS (1 << 4) /* kfunc only takes trusted pointer > arguments */ > > +#define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */ > > > > struct btf; > > struct btf_member; > > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > > index 7e64447659f3..d3e4c86b8fcd 100644 > > --- a/kernel/bpf/btf.c > > +++ b/kernel/bpf/btf.c > > @@ -6175,6 +6175,7 @@ static int btf_check_func_arg_match(struct > bpf_verifier_env *env, > > { > > enum bpf_prog_type prog_type = resolve_prog_type(env->prog); > > bool rel = false, kptr_get = false, trusted_arg = false; > > + bool sleepable = false; > > struct bpf_verifier_log *log = &env->log; > > u32 i, nargs, ref_id, ref_obj_id = 0; > > bool is_kfunc = btf_is_kernel(btf); > > @@ -6212,6 +6213,7 @@ static int btf_check_func_arg_match(struct > bpf_verifier_env *env, > > rel = kfunc_flags & KF_RELEASE; > > kptr_get = kfunc_flags & KF_KPTR_GET; > > trusted_arg = kfunc_flags & KF_TRUSTED_ARGS; > > + sleepable = kfunc_flags & KF_SLEEPABLE; > > } > > > > /* check that BTF function arguments match actual types that the > > @@ -6419,6 +6421,13 @@ static int btf_check_func_arg_match(struct > bpf_verifier_env *env, > > func_name); > > return -EINVAL; > > } > > + > > + if (sleepable && !env->prog->aux->sleepable) { > > + bpf_log(log, "kernel function %s is sleepable but the program is > not\n", > > + func_name); > > + return -EINVAL; > > + } > > + > > /* returns argument register number > 0 in case of reference release > kfunc */ > > return rel ? ref_regno : 0; > > } > > -- > > 2.25.1 > > > > BR, Jarkko