From patchwork Mon Aug 14 18:59:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Vernet X-Patchwork-Id: 13353200 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 728AACA6A; Mon, 14 Aug 2023 18:59:23 +0000 (UTC) Received: from mail-qt1-f170.google.com (mail-qt1-f170.google.com [209.85.160.170]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8519310F2; Mon, 14 Aug 2023 11:59:22 -0700 (PDT) Received: by mail-qt1-f170.google.com with SMTP id d75a77b69052e-40ff796e8ddso36052591cf.2; Mon, 14 Aug 2023 11:59:22 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692039561; x=1692644361; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=tFsZYglbIoheMRdnUX+qlZ0MFAe72xqHNVYG2PQUmMI=; b=kmlHjjL+NrrCbl48hiCNs3SFWVjWqyUuvQkwkx1W/MxM3BEZAKa9YbJ0iYtQPvLROd EGfrWtvrzW0pm/jHPdzz8gG+wvP1yIYkS4peLkZ59KzTivbrq64Fwy3FJU9v08aSshGv 2wLfQX9PLHB3k0nzqpc4Z0gfJIiDH4BaZ6bsCvwapwbjm7DIm/j2gpDJPg7pfXGc+mcK NQ60ygvhc30WCWPyACc1rXqf9V71GEbJHsPmvIZyWkcTQmaj+2MTzaI7BFXHAeVAitCO SJGua1QlD117IvMzBMK7P6lkSORoSdYxMCLNE1BMS8oWjPh95Zexwiw130Ek6RvsGB3T dWMA== X-Gm-Message-State: AOJu0YxCkalGLFLit1P3zgmdHHDazMPxPyXeDgzgFSemZ62FcK3YdIBJ MJXCxdf4D2fWi/QkBm++7s2aDRXUxvUBuBa9 X-Google-Smtp-Source: AGHT+IFrP3BKp7vJH8r6t9jh/zesUXJcFDd7e6j/KQDpSz31cru/oAx9m+dOyy1rkEiPQvfFCgdsHQ== X-Received: by 2002:ac8:5b91:0:b0:40f:bc9a:3262 with SMTP id a17-20020ac85b91000000b0040fbc9a3262mr13578948qta.21.1692039561291; Mon, 14 Aug 2023 11:59:21 -0700 (PDT) Received: from localhost ([2620:10d:c091:400::5:93a1]) by smtp.gmail.com with ESMTPSA id m19-20020ac86893000000b00403cce833eesm3288487qtq.27.2023.08.14.11.59.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Aug 2023 11:59:20 -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, netdev@vger.kernel.org Subject: [PATCH bpf-next v3 1/2] bpf: Support default .validate() and .update() behavior for struct_ops links Date: Mon, 14 Aug 2023 13:59:07 -0500 Message-ID: <20230814185908.700553-2-void@manifault.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230814185908.700553-1-void@manifault.com> References: <20230814185908.700553-1-void@manifault.com> 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_H3,RCVD_IN_MSPIKE_WL, 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. Acked-by: Kui-Feng Lee Signed-off-by: David Vernet --- 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)); From patchwork Mon Aug 14 18:59:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Vernet X-Patchwork-Id: 13353201 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 05ED8CA69; Mon, 14 Aug 2023 18:59:24 +0000 (UTC) Received: from mail-qk1-f178.google.com (mail-qk1-f178.google.com [209.85.222.178]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CF3ECBC; Mon, 14 Aug 2023 11:59:23 -0700 (PDT) Received: by mail-qk1-f178.google.com with SMTP id af79cd13be357-76cdf055c64so386154885a.3; Mon, 14 Aug 2023 11:59:23 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692039562; x=1692644362; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=SGuj3pRVjvLXxFets6pK1U3+m8DANPeXEAyiVK4FKOo=; b=Gwp8n/6UzoBCJaYg7AceV+/mpHWDJWuiAVCA7eVGfON4NuguGjk1WGr1/CXMvBUsLP aCC96+sw2hKzbxtyW3kpkKOTmV8qDtH2n+bpG8j7gidf5XBGHuCyQBnXz0fNWYREhxlQ 6SyP9usJbR6a2ZThQoibnc68B2yON4h65J5UlsT51iLBDoHWRGonWxpWTeClloMAkWJu LoHouk3+dIXpEpP9N6QcNqwbi6xq+Hx1T1a3APR5VMw5DF5W2k7FAAZcnIQj753Ev6y+ rLF7f9zXFgbiUboySuDvddv9nDf/5aJSzxKufuW59yDwmSC8oZimrd82ugLJM2d9vAaB +RqA== X-Gm-Message-State: AOJu0YzMnUFps/MtGO354xL+wUxOmO/iDC7RcNmSSlnU+NWJTZdh+4/B YtGCds/6w0muCqdEmjmaPKgBW3nGjaYBpeiZ X-Google-Smtp-Source: AGHT+IFUNtzoTJG24F+eBhk7JKeQDXT+j2FaivAC15MMTksndaxp3DTkXBifnR3oVJtUN6DYq9TXeg== X-Received: by 2002:a05:620a:424b:b0:75b:23a0:deca with SMTP id w11-20020a05620a424b00b0075b23a0decamr12422534qko.72.1692039562527; Mon, 14 Aug 2023 11:59:22 -0700 (PDT) Received: from localhost ([2620:10d:c091:400::5:93a1]) by smtp.gmail.com with ESMTPSA id u2-20020ae9c002000000b00767c961eb47sm3217269qkk.43.2023.08.14.11.59.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Aug 2023 11:59:22 -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, netdev@vger.kernel.org Subject: [PATCH bpf-next v3 2/2] bpf: Document struct bpf_struct_ops fields Date: Mon, 14 Aug 2023 13:59:08 -0500 Message-ID: <20230814185908.700553-3-void@manifault.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230814185908.700553-1-void@manifault.com> References: <20230814185908.700553-1-void@manifault.com> 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 Subsystems that want to implement a struct bpf_struct_ops structure to enable struct_ops maps must currently reverse engineer how the structure works. Given that this is meant to be a way for subsystem maintainers to extend their subsystems using BPF, let's document it to make it a bit easier on them. Signed-off-by: David Vernet --- include/linux/bpf.h | 47 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index cfabbcf47bdb..eced6400f778 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1550,6 +1550,53 @@ struct bpf_struct_ops_value; struct btf_member; #define BPF_STRUCT_OPS_MAX_NR_MEMBERS 64 +/** + * struct bpf_struct_ops - A structure of callbacks allowing a subsystem to + * define a BPF_MAP_TYPE_STRUCT_OPS map type composed + * of BPF_PROG_TYPE_STRUCT_OPS progs. + * @verifier_ops: A structure of callbacks that are invoked by the verifier + * when determining whether the struct_ops progs in the + * struct_ops map are valid. + * @init: A callback that is invoked a single time, and before any other + * callback, to initialize the structure. A nonzero return value means + * the subsystem could not be initialized. + * @check_member: When defined, a callback invoked by the verifier to allow + * the subsystem to determine if an entry in the struct_ops map + * is valid. A nonzero return value means that the map is + * invalid and should be rejected by the verifier. + * @init_member: A callback that is invoked for each member of the struct_ops + * map to allow the subsystem to initialize the member. A nonzero + * value means the member could not be initialized. This callback + * is exclusive with the @type, @type_id, @value_type, and + * @value_id fields. + * @reg: A callback that is invoked when the struct_ops map has been + * initialized and is being attached to. Zero means the struct_ops map + * has been successfully registered and is live. A nonzero return value + * means the struct_ops map could not be registered. + * @unreg: A callback that is invoked when the struct_ops map should be + * unregistered. + * @update: A callback that is invoked when the live struct_ops map is being + * updated to contain new values. This callback is only invoked when + * the struct_ops map is loaded with BPF_F_LINK. If not defined, the + * it is assumed that the struct_ops map cannot be updated. + * @validate: A callback that is invoked after all of the members have been + * initialized. This callback should perform static checks on the + * map, meaning that it should either fail or succeed + * deterministically. A struct_ops map that has been validated may + * not necessarily succeed in being registered if the call to @reg + * fails. For example, a valid struct_ops map may be loaded, but + * then fail to be registered due to there being another active + * struct_ops map on the system in the subsystem already. For this + * reason, if this callback is not defined, the check is skipped as + * the struct_ops map will have final verification performed in + * @reg. + * @type: BTF type. + * @value_type: Value type. + * @name: The name of the struct bpf_struct_ops object. + * @func_models: Func models + * @type_id: BTF type id. + * @value_id: BTF value id. + */ struct bpf_struct_ops { const struct bpf_verifier_ops *verifier_ops; int (*init)(struct btf *btf);