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 X-Spam-Level: X-Spam-Status: No, score=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 01A88C433ED for ; Thu, 29 Apr 2021 11:24:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A961A61445 for ; Thu, 29 Apr 2021 11:24:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231708AbhD2LZV (ORCPT ); Thu, 29 Apr 2021 07:25:21 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:33562 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230148AbhD2LZU (ORCPT ); Thu, 29 Apr 2021 07:25:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1619695474; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=2Hrmp60pTQWrZ956xjnp/+jusKgysHgdmxCB+fDAXuY=; b=dwrZZUats37oYtFfUlWBy5c/AfDPGgerz7HPu3gDmJ9Oi41/9tEDXNy9mumtsBVbCWi10e joWsD8r1UzxfwFd4M0oqb7JfZq18tAIQ04HMIkYKR1z7BJkSlVciDQr0fJ2lSHyjpPfaNH Z6lWu2LLerg8EESbT01Dx7b1g3RV/FU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-508-cP75KLOLOPOBAS6YB3g0RQ-1; Thu, 29 Apr 2021 07:24:30 -0400 X-MC-Unique: cP75KLOLOPOBAS6YB3g0RQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A41538189C3; Thu, 29 Apr 2021 11:24:28 +0000 (UTC) Received: from krava (unknown [10.40.195.102]) by smtp.corp.redhat.com (Postfix) with SMTP id F2265100164C; Thu, 29 Apr 2021 11:24:25 +0000 (UTC) Date: Thu, 29 Apr 2021 13:24:25 +0200 From: Jiri Olsa To: Andrii Nakryiko Cc: Jiri Olsa , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Networking , bpf , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh Subject: Re: [PATCH] bpf: Add deny list of btf ids check for tracing and ext programs Message-ID: References: <20210428161802.771519-1-jolsa@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, Apr 28, 2021 at 12:41:34PM -0700, Andrii Nakryiko wrote: > On Wed, Apr 28, 2021 at 9:19 AM Jiri Olsa wrote: > > > > The recursion check in __bpf_prog_enter and __bpf_prog_exit > > leaves some (not inlined) functions unprotected: > > > > In __bpf_prog_enter: > > - migrate_disable is called before prog->active is checked > > > > In __bpf_prog_exit: > > - migrate_enable,rcu_read_unlock_strict are called after > > prog->active is decreased > > > > When attaching trampoline to them we get panic like: > > > > traps: PANIC: double fault, error_code: 0x0 > > double fault: 0000 [#1] SMP PTI > > RIP: 0010:__bpf_prog_enter+0x4/0x50 > > ... > > Call Trace: > > > > bpf_trampoline_6442466513_0+0x18/0x1000 > > migrate_disable+0x5/0x50 > > __bpf_prog_enter+0x9/0x50 > > bpf_trampoline_6442466513_0+0x18/0x1000 > > migrate_disable+0x5/0x50 > > __bpf_prog_enter+0x9/0x50 > > bpf_trampoline_6442466513_0+0x18/0x1000 > > migrate_disable+0x5/0x50 > > __bpf_prog_enter+0x9/0x50 > > bpf_trampoline_6442466513_0+0x18/0x1000 > > migrate_disable+0x5/0x50 > > ... > > > > Fixing this by adding deny list of btf ids for tracing > > and ext programs and checking btf id during program > > verification. Adding above functions to this list. > > > > Suggested-by: Alexei Starovoitov > > Signed-off-by: Jiri Olsa > > --- > > kernel/bpf/verifier.c | 15 +++++++++++++++ > > 1 file changed, 15 insertions(+) > > > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > > index 2579f6fbb5c3..4ffd64eaffda 100644 > > --- a/kernel/bpf/verifier.c > > +++ b/kernel/bpf/verifier.c > > @@ -13112,6 +13112,17 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, > > return 0; > > } > > > > +BTF_SET_START(btf_id_deny) > > +BTF_ID_UNUSED > > +#ifdef CONFIG_SMP > > +BTF_ID(func, migrate_disable) > > +BTF_ID(func, migrate_enable) > > +#endif > > +#if !defined CONFIG_PREEMPT_RCU && !defined CONFIG_TINY_RCU > > +BTF_ID(func, rcu_read_unlock_strict) > > +#endif > > +BTF_SET_END(btf_id_deny) > > + > > static int check_attach_btf_id(struct bpf_verifier_env *env) > > { > > struct bpf_prog *prog = env->prog; > > @@ -13171,6 +13182,10 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) > > ret = bpf_lsm_verify_prog(&env->log, prog); > > if (ret < 0) > > return ret; > > + } else if ((prog->type == BPF_PROG_TYPE_TRACING || > > + prog->type == BPF_PROG_TYPE_EXT) && > > BPF_PROG_TYP_EXT can only replace other BPF programs/subprograms, it > can't replace kernel functions, so the deny list shouldn't be checked > for them. right, will send new version jirka > > > + btf_id_set_contains(&btf_id_deny, btf_id)) { > > + return -EINVAL; > > } > > > > key = bpf_trampoline_compute_key(tgt_prog, prog->aux->attach_btf, btf_id); > > -- > > 2.30.2 > > >