From patchwork Fri Aug 11 17:25:41 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Vernet X-Patchwork-Id: 13351238 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 0A5871172E for ; Fri, 11 Aug 2023 17:25:46 +0000 (UTC) Received: from mail-yb1-f175.google.com (mail-yb1-f175.google.com [209.85.219.175]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4514A30CB; Fri, 11 Aug 2023 10:25:45 -0700 (PDT) Received: by mail-yb1-f175.google.com with SMTP id 3f1490d57ef6-bc379e4c1cbso2081687276.2; Fri, 11 Aug 2023 10:25:45 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691774744; x=1692379544; 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=jGoJuAaL7UedDzvJJkHogM35NrJIaiMLcIhsmtcuEcI=; b=Pb5SCI1zVXIof06x0ZLuTr5oDuSLIHSHZ51Y0B70UVhDi/7rd+zck9wcI2kg7q7JwR QhVkhLT2neT/J7n//1yyS4U+1llyJ/oNPWiZDVWOZ5DaOVFcYOjcBH4+Zo56RZLUaVa1 iL2wvZh/gVXbrRLhKGHzZM7zt54wpkAiCyEEpdYN/mjTPOE3r/nlFm5zcuNRnmdQP+uR knm4U45WybbpJyJUsGIppV1Zk5xODgNbyPhrcDO61mmYCc/E8AN/wALe58awPot8Wh/x EXQsw9/TorBLyLTyK1iC9Z2n9E83f0RBAKIEVx1tZbJPusTw9DeEG3ryJqFvCHkd4uie zo2A== X-Gm-Message-State: AOJu0YxPc6u6TIWBtqJdWY3jAcV31d2ldyfQeBycJLtldmxvwYZdGsb0 FYZOYYTN4itv+AukM1lUWbY9qnnj6MiNrhJD X-Google-Smtp-Source: AGHT+IESHCldMhz2zO7cLkf4tUyRGKg/MK0ARvlUjbho5c24JvyLyEsyeDF20WThnlQD9RRG60Cs7g== X-Received: by 2002:a25:b19c:0:b0:d53:f88a:dc09 with SMTP id h28-20020a25b19c000000b00d53f88adc09mr3003890ybj.2.1691774744160; Fri, 11 Aug 2023 10:25:44 -0700 (PDT) Received: from localhost ([24.1.27.177]) by smtp.gmail.com with ESMTPSA id g9-20020a256b09000000b00cf79d3a503fsm981762ybc.42.2023.08.11.10.25.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Aug 2023 10:25:43 -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, yonghong.song@linux.dev, 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 v2] bpf: Support default .validate() and .update() behavior for struct_ops links Date: Fri, 11 Aug 2023 12:25:41 -0500 Message-ID: <20230811172541.618284-1-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_BLOCKED,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 Acked-by: Kui-Feng Lee --- kernel/bpf/bpf_struct_ops.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index eaff04eefb31..fdc3e8705a3c 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) + @@ -823,6 +823,9 @@ static int bpf_struct_ops_map_link_update(struct bpf_link *link, struct bpf_map if (!bpf_struct_ops_valid_to_reg(new_map)) return -EINVAL; + if (!st_map->st_ops->update) + return -EOPNOTSUPP; + mutex_lock(&update_mutex); old_map = rcu_dereference_protected(st_link->map, lockdep_is_held(&update_mutex));