From patchwork Thu Aug 10 22:04:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Vernet X-Patchwork-Id: 13349959 X-Patchwork-Delegate: bpf@iogearbox.net Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E9B9922F02 for ; Thu, 10 Aug 2023 22:05:10 +0000 (UTC) Received: from mail-qk1-f169.google.com (mail-qk1-f169.google.com [209.85.222.169]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E31042123; Thu, 10 Aug 2023 15:05:09 -0700 (PDT) Received: by mail-qk1-f169.google.com with SMTP id af79cd13be357-76c8dd2ce79so114764085a.1; Thu, 10 Aug 2023 15:05:09 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691705109; x=1692309909; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=aFjkqjJ2FVdTFKrxffUkW0MiERwjfIJkGtRrXjfMlRg=; b=PpDBuX4+CX94MTfOiRJWRTmaXzOk+GhkXHfml+DYm8XeqXzAmmfiu+h94J7biYGlDv 7hPgEfbzrt2GulnkvAvcielkOYhkcJbqO8xKQxZcgly9kObQ91rT8Ez7ujdtrSOpStfm ssIVldsjhwvS+VaRHoLaGF/a5ZuERE6jkagOzaTXNp9eqTywyxI+L5wdPMxm8ki7spct HaYoTYxFYy5O5N21EQK1HxTYMJxYyNFpI31vJ1rOVmSxAB4hzUfj+GIbNilem+BkCt7r e1K7nRLsPfz3ApiXDwp5wxRvMyax6kR5UOuOY3XGZQKEDoRVkw8bdlMYW57c7cvhagcr CE0A== X-Gm-Message-State: AOJu0YwO0JZU2iX4B6ACNI+tvvYWrt8fcGWuV+hpvs24NZSRgY3sCFDZ j7Au+shc5CdBq6s6r3uNw2uu03AfABPoxUEr X-Google-Smtp-Source: AGHT+IENK/+KAi6n28GpOvj2pkywcPRdPdwKuCuLe6XXOVQRvanxlY5xzTWyNV4xam9K+joUt0N98g== X-Received: by 2002:a05:620a:25cf:b0:76c:9427:5c54 with SMTP id y15-20020a05620a25cf00b0076c94275c54mr109875qko.27.1691705108724; Thu, 10 Aug 2023 15:05:08 -0700 (PDT) Received: from localhost ([2620:10d:c091:400::5:d81f]) by smtp.gmail.com with ESMTPSA id x8-20020ae9f808000000b0076cdc3b5beasm782788qkh.86.2023.08.10.15.05.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Aug 2023 15:05:08 -0700 (PDT) From: David Vernet To: bpf@vger.kernel.org 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, linux-kernel@vger.kernel.org, kernel-team@meta.com, tj@kernel.org, clm@meta.com, thinker.li@gmail.com Subject: [PATCH bpf-next] bpf: Support default .validate() and .update() behavior for struct_ops links Date: Thu, 10 Aug 2023 17:04:56 -0500 Message-ID: <20230810220456.521517-1-void@manifault.com> X-Mailer: git-send-email 2.41.0 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-1.4 required=5.0 tests=BAYES_00, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: bpf@iogearbox.net Currently, if a struct_ops map is loaded with BPF_F_LINK, it must also define the .validate() and .update() callbacks in its corresponding struct bpf_struct_ops in the kernel. Enabling struct_ops link is useful in its own right to ensure that the map is unloaded if an application crashes. For example, with sched_ext, we want to automatically unload the host-wide scheduler if the application crashes. We would likely never support updating elements of a sched_ext struct_ops map, so we'd have to implement these callbacks showing that they _can't_ support element updates just to benefit from the basic lifetime management of struct_ops links. Let's enable struct_ops maps to work with BPF_F_LINK even if they haven't defined these callbacks, by assuming that a struct_ops map element cannot be updated by default. Signed-off-by: David Vernet --- kernel/bpf/bpf_struct_ops.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index eaff04eefb31..3d2fb85186a9 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -509,9 +509,12 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, } if (st_map->map.map_flags & BPF_F_LINK) { - err = st_ops->validate(kdata); - if (err) - goto reset_unlock; + err = 0; + if (st_ops->validate) { + err = st_ops->validate(kdata); + if (err) + goto reset_unlock; + } set_memory_rox((long)st_map->image, 1); /* Let bpf_link handle registration & unregistration. * @@ -663,9 +666,6 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) if (attr->value_size != vt->size) return ERR_PTR(-EINVAL); - if (attr->map_flags & BPF_F_LINK && (!st_ops->validate || !st_ops->update)) - return ERR_PTR(-EOPNOTSUPP); - t = st_ops->type; st_map_size = sizeof(*st_map) + @@ -838,6 +838,11 @@ static int bpf_struct_ops_map_link_update(struct bpf_link *link, struct bpf_map goto err_out; } + if (!st_map->st_ops->update) { + err = -EOPNOTSUPP; + goto err_out; + } + err = st_map->st_ops->update(st_map->kvalue.data, old_st_map->kvalue.data); if (err) goto err_out;