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 35CB6C43217 for ; Tue, 15 Nov 2022 23:27:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231419AbiKOX04 (ORCPT ); Tue, 15 Nov 2022 18:26:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37012 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230260AbiKOX0e (ORCPT ); Tue, 15 Nov 2022 18:26:34 -0500 Received: from mail-ej1-x62e.google.com (mail-ej1-x62e.google.com [IPv6:2a00:1450:4864:20::62e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 97C9E27908 for ; Tue, 15 Nov 2022 15:26:32 -0800 (PST) Received: by mail-ej1-x62e.google.com with SMTP id f18so7061825ejz.5 for ; Tue, 15 Nov 2022 15:26:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:from:to:cc:subject:date:message-id:reply-to; bh=DY++N/b93BxdltXMTeLdUPgzPkCVBFPWyIHIT+cRgeQ=; b=UfLpknoHmLMzJZwKQ0I/rchQv4UdGcbstofMOgR3/JRLKdD3mAfexK6TFqArJ1aVLd AkbA9FI7twN6R5Bf+1wqFhirLiCG+cBApyGM5TPp+VZknPfwCL8zR75eVR71GRB8Qo24 t/m1UTe21EKBTJVY9LTr8kUx3fd9cT/L5BCD/1JFpnKyQXduvEN0I9We3BuOUHoduWEJ wlUNmgO2kNXat+N6veY4hGr2kFl4jwmOHAJdXb232ah6Rl9v+Guo0cQwPJm39VznlKD1 vVTZurhQn3OrvqnAAx6802UIUtelimet+Cg3dAbegcTBxhpKUZDNTnaXgY+A29/wanCz Xm7A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=DY++N/b93BxdltXMTeLdUPgzPkCVBFPWyIHIT+cRgeQ=; b=FU1Emhzt53i959MkbzAsB3AthuZfIC/09Bo3LNcHWr4KsLxFR7/lG18/0sZwOxcIaQ 2wCGlpMLF+n8BeQ4nWWXrGW5awrHBhFWSOU+QjIgdo0Zmk0fDIZRjqHry+AwWLC3OX4T apF7Yw2mxY+GVk7wAxuvld43+ZhTvNmyWcn9TVjAUewgG3+DHhHuSIuTdCAJyUh2ZepA qWg5Vt3RXI3ya66OaOl05QNtwYhHgCpFRHbgLfdrSAi0mmRZ8GgTxk9dWoCWzZDIf7Ch nOWeYkcAC7Z/joQAQOwZ8Iqvo9cJgE8sMpLLsC/DJzn3TeDcuBGfYAXXbrGSaMaEZSM1 ymvA== X-Gm-Message-State: ANoB5pk2Bx2rFaubxgKsX2ApcECyZs53oAG1SjemvYGhsEEUGjDxClcI PRgCNnD8rMyqiLCnzEBqTys= X-Google-Smtp-Source: AA0mqf7IZ9q1lqJm7/yPihcbLxDnHT5VMy7I5LfhDM+o3Khg484ZdDpTKwoCcvwDggcR6tY8jKHFXQ== X-Received: by 2002:a17:906:3e05:b0:78d:aaf9:7b8c with SMTP id k5-20020a1709063e0500b0078daaf97b8cmr16155052eji.229.1668554791006; Tue, 15 Nov 2022 15:26:31 -0800 (PST) Received: from krava ([83.240.62.198]) by smtp.gmail.com with ESMTPSA id la8-20020a170907780800b00781b589a1afsm6110483ejc.159.2022.11.15.15.26.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Nov 2022 15:26:30 -0800 (PST) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Wed, 16 Nov 2022 00:26:28 +0100 To: Daniel Borkmann , Martin KaFai Lau Cc: Alexei Starovoitov , Andrii Nakryiko , bpf@vger.kernel.org, Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jakub Kicinski Subject: Re: [RFC bpf-next] bpf: Fix perf bpf event and audit prog id logging Message-ID: References: <20221115095043.1249776-1-jolsa@kernel.org> <4d91b1d3-3ffc-11f9-50a6-bfb503e4b3cd@iogearbox.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4d91b1d3-3ffc-11f9-50a6-bfb503e4b3cd@iogearbox.net> Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Tue, Nov 15, 2022 at 01:49:54PM +0100, Daniel Borkmann wrote: > On 11/15/22 10:50 AM, Jiri Olsa wrote: > > hi, > > perf_event_bpf_event and bpf_audit_prog calls currently report zero > > program id for unload path. > > > > It's because of the [1] change moved those audit calls into work queue > > and they are executed after the id is zeroed in bpf_prog_free_id. > > > > I originally made a change that added 'id_audit' field to struct > > bpf_prog, which would be initialized as id, untouched and used > > in audit callbacks. > > > > Then I realized we might actually not need to zero prog->aux->id > > in bpf_prog_free_id. It seems to be called just once on release > > paths. Tests seems ok with that. > > > > thoughts? > > > > thanks, > > jirka > > > > > > [1] d809e134be7a ("bpf: Prepare bpf_prog_put() to be called from irq context.") > > --- > > kernel/bpf/syscall.c | 1 - > > 1 file changed, 1 deletion(-) > > > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > > index fdbae52f463f..426529355c29 100644 > > --- a/kernel/bpf/syscall.c > > +++ b/kernel/bpf/syscall.c > > @@ -1991,7 +1991,6 @@ void bpf_prog_free_id(struct bpf_prog *prog, bool do_idr_lock) > > __acquire(&prog_idr_lock); > > idr_remove(&prog_idr, prog->aux->id); > > - prog->aux->id = 0; > > This would trigger a race when offloaded progs are used, see also ad8ad79f4f60 ("bpf: > offload: free program id when device disappears"). __bpf_prog_offload_destroy() calls > it, and my read is that later bpf_prog_free_id() then hits the early !prog->aux->id > return path. Is there a reason for irq context to not defer the bpf_prog_free_id()? there's comment saying: /* bpf_prog_free_id() must be called first */ it was added together with the BPF_(PROG|MAP)_GET_NEXT_ID api: 34ad5580f8f9 bpf: Add BPF_(PROG|MAP)_GET_NEXT_ID command Martin, any idea? while looking on this I noticed we can remove the do_idr_lock argument (patch below) because it's always true and I think we need to upgrade all the prog_idr_lock locks to spin_lock_irqsave because bpf_prog_put could be called from irq context because of d809e134be7a thanks, jirka --- diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 49f9d2bec401..50c71ce698d0 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1761,7 +1761,7 @@ void bpf_prog_inc(struct bpf_prog *prog); struct bpf_prog * __must_check bpf_prog_inc_not_zero(struct bpf_prog *prog); void bpf_prog_put(struct bpf_prog *prog); -void bpf_prog_free_id(struct bpf_prog *prog, bool do_idr_lock); +void bpf_prog_free_id(struct bpf_prog *prog); void bpf_map_free_id(struct bpf_map *map, bool do_idr_lock); struct btf_field *btf_record_find(const struct btf_record *rec, diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c index 13e4efc971e6..327dab644200 100644 --- a/kernel/bpf/offload.c +++ b/kernel/bpf/offload.c @@ -217,7 +217,7 @@ static void __bpf_prog_offload_destroy(struct bpf_prog *prog) offload->offdev->ops->destroy(prog); /* Make sure BPF_PROG_GET_NEXT_ID can't find this dead program */ - bpf_prog_free_id(prog, true); + bpf_prog_free_id(prog); list_del_init(&offload->offloads); kfree(offload); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index fdbae52f463f..9b929d8ab06d 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1973,7 +1973,7 @@ static int bpf_prog_alloc_id(struct bpf_prog *prog) return id > 0 ? 0 : id; } -void bpf_prog_free_id(struct bpf_prog *prog, bool do_idr_lock) +void bpf_prog_free_id(struct bpf_prog *prog) { unsigned long flags; @@ -1985,18 +1985,12 @@ void bpf_prog_free_id(struct bpf_prog *prog, bool do_idr_lock) if (!prog->aux->id) return; - if (do_idr_lock) - spin_lock_irqsave(&prog_idr_lock, flags); - else - __acquire(&prog_idr_lock); + spin_lock_irqsave(&prog_idr_lock, flags); idr_remove(&prog_idr, prog->aux->id); prog->aux->id = 0; - if (do_idr_lock) - spin_unlock_irqrestore(&prog_idr_lock, flags); - else - __release(&prog_idr_lock); + spin_unlock_irqrestore(&prog_idr_lock, flags); } static void __bpf_prog_put_rcu(struct rcu_head *rcu) @@ -2048,7 +2042,7 @@ static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock) if (atomic64_dec_and_test(&aux->refcnt)) { /* bpf_prog_free_id() must be called first */ - bpf_prog_free_id(prog, do_idr_lock); + bpf_prog_free_id(prog); if (in_irq() || irqs_disabled()) { INIT_WORK(&aux->work, bpf_prog_put_deferred);