From patchwork Sun Dec 17 08:11:25 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kui-Feng Lee X-Patchwork-Id: 13495797 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mail-yb1-f174.google.com (mail-yb1-f174.google.com [209.85.219.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0DC4520EB for ; Sun, 17 Dec 2023 08:11:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="YC+zJagY" Received: by mail-yb1-f174.google.com with SMTP id 3f1490d57ef6-d9caf5cc948so1369937276.0 for ; Sun, 17 Dec 2023 00:11:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1702800712; x=1703405512; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=VbQZZ67EiRiEqYh2CTsAlBEPPvOMdkhTkwDC7DgRYmM=; b=YC+zJagYzYpsauxyX7D9WyuNKaZB0XoNWS48l/TdxIJajoQDGPpFxd0zaU5/9+pp9U ZsrCuMoT+V4L04XZfIxTP9djR3uhI24lTB4pi10W6RmFMfpHeKcrkptgEj1BnwAyJPCB pFbKgEWLXZhd7Ski30OWBPe/xP/pWpKLBLitN6VU9lPF8bWWLhccUZcq5Lz3LcPVYng+ ++EbzGzUn208HECzyxVRUf5lwAoDz1KDzlhcaWLD7AtMQKCv172ASf00vC2JSznZ18ng F94YLnRsZShg47Yp37aZmnzprIPpJlZ02/l8yJBADWOpFIG0gCW/cxm0m66tv9dIhtgr 0FEQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702800712; x=1703405512; 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=VbQZZ67EiRiEqYh2CTsAlBEPPvOMdkhTkwDC7DgRYmM=; b=owvdGwXwQOf1dY9Cp56Ubog8b/0RzYuC9Lb2+0ol4wD6pfk+fTuzO1EYNxm28P1+eQ VW4pQoVq00ehBfiNt9OeacAW6Cthb8nFa+GJXnHUiWu7jv4WIwNvzwjuLphNhaYmvERq Kt1fLJb+ClVoTtu4tAGBh+GPmlFljYX8L7rIaY6u2E2Eu7mLg04NKr/oJgUGJ6lW+hBW I/PMvssPEB2x/65y5KtEC6ZTt50IJp2BruoWORXevqsPO26l9OUJlwFOEXZ7Pc3NW1WC On40JixJtmjWxODvpQBMMJEriLlGRHU9cRc1pwRrnzWiUJB7GRE23pt9Dp89ty7jDYtK EVxg== X-Gm-Message-State: AOJu0YxINW9ZF5rcFsPbFcABKuEqwzVAVOpeKwAZzkQG+dbP0THz2IPa PRZ8HkWc1eNQbsoekBGvclxp6HwUF3Y= X-Google-Smtp-Source: AGHT+IHY/lBmwHz45gkmSAoQbcPFGioBFYXwVWdf6wEHvP3W4/KP0jjTg0HZ6HsS6QdHb8SOI9bUUA== X-Received: by 2002:a0d:d9d0:0:b0:5e5:3d3:4e97 with SMTP id b199-20020a0dd9d0000000b005e503d34e97mr1607435ywe.101.1702800711716; Sun, 17 Dec 2023 00:11:51 -0800 (PST) Received: from kickker.attlocal.net ([2600:1700:6cf8:1240:bb8c:c0f2:4408:50cf]) by smtp.gmail.com with ESMTPSA id c85-20020a814e58000000b005e303826838sm3399415ywb.56.2023.12.17.00.11.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 17 Dec 2023 00:11:51 -0800 (PST) From: thinker.li@gmail.com To: bpf@vger.kernel.org, ast@kernel.org, martin.lau@linux.dev, song@kernel.org, kernel-team@meta.com, andrii@kernel.org, drosen@google.com Cc: sinquersw@gmail.com, kuifeng@meta.com, Kui-Feng Lee Subject: [PATCH bpf-next v14 08/14] bpf: pass attached BTF to the bpf_struct_ops subsystem Date: Sun, 17 Dec 2023 00:11:25 -0800 Message-Id: <20231217081132.1025020-9-thinker.li@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231217081132.1025020-1-thinker.li@gmail.com> References: <20231217081132.1025020-1-thinker.li@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net From: Kui-Feng Lee Pass the fd of a btf from the userspace to the bpf() syscall, and then convert the fd into a btf. The btf is generated from the module that defines the target BPF struct_ops type. In order to inform the kernel about the module that defines the target struct_ops type, the userspace program needs to provide a btf fd for the respective module's btf. This btf contains essential information on the types defined within the module, including the target struct_ops type. A btf fd must be provided to the kernel for struct_ops maps struct_ops and for the bpf programs attached to those maps. In the case of the bpf programs, the attach_btf_obj_fd parameter is passed as part of the bpf_attr and is converted into a btf. This btf is then stored in the prog->aux->attach_btf field. Here, it just let the verifier access attach_btf directly. In the case of struct_ops maps, a btf fd is passed as value_type_btf_obj_fd of bpf_attr. The bpf_struct_ops_map_alloc() function converts the fd to a btf and stores it as st_map->btf. Signed-off-by: Kui-Feng Lee --- include/uapi/linux/bpf.h | 5 +++ kernel/bpf/bpf_struct_ops.c | 62 ++++++++++++++++++++++++---------- kernel/bpf/syscall.c | 2 +- kernel/bpf/verifier.c | 9 +++-- tools/include/uapi/linux/bpf.h | 5 +++ 5 files changed, 62 insertions(+), 21 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 7ab00babcccc..d72a16adfbb3 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1438,6 +1438,11 @@ union bpf_attr { */ __u64 map_extra; __u32 map_token_fd; + + __u32 value_type_btf_obj_fd; /* fd pointing to a BTF + * type data for + * btf_vmlinux_value_type_id. + */ }; struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */ diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index bda31cc3bab0..381175f97b25 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -641,6 +641,7 @@ static void __bpf_struct_ops_map_free(struct bpf_map *map) bpf_jit_uncharge_modmem(PAGE_SIZE); } bpf_map_area_free(st_map->uvalue); + btf_put(st_map->btf); bpf_map_area_free(st_map); } @@ -681,15 +682,36 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) struct bpf_struct_ops_map *st_map; const struct btf_type *t, *vt; struct bpf_map *map; + struct btf *btf; int ret; - st_ops_desc = bpf_struct_ops_find_value(btf_vmlinux, attr->btf_vmlinux_value_type_id); - if (!st_ops_desc) - return ERR_PTR(-ENOTSUPP); + if (attr->value_type_btf_obj_fd) { + /* The map holds btf for its whole life time. */ + btf = btf_get_by_fd(attr->value_type_btf_obj_fd); + if (IS_ERR(btf)) + return ERR_CAST(btf); + if (!btf_is_module(btf)) { + btf_put(btf); + return ERR_PTR(-EINVAL); + } + } else { + btf = bpf_get_btf_vmlinux(); + if (IS_ERR(btf)) + return ERR_CAST(btf); + btf_get(btf); + } + + st_ops_desc = bpf_struct_ops_find_value(btf, attr->btf_vmlinux_value_type_id); + if (!st_ops_desc) { + ret = -ENOTSUPP; + goto errout; + } vt = st_ops_desc->value_type; - if (attr->value_size != vt->size) - return ERR_PTR(-EINVAL); + if (attr->value_size != vt->size) { + ret = -EINVAL; + goto errout; + } t = st_ops_desc->type; @@ -700,17 +722,17 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) (vt->size - sizeof(struct bpf_struct_ops_value)); st_map = bpf_map_area_alloc(st_map_size, NUMA_NO_NODE); - if (!st_map) - return ERR_PTR(-ENOMEM); + if (!st_map) { + ret = -ENOMEM; + goto errout; + } st_map->st_ops_desc = st_ops_desc; map = &st_map->map; ret = bpf_jit_charge_modmem(PAGE_SIZE); - if (ret) { - __bpf_struct_ops_map_free(map); - return ERR_PTR(ret); - } + if (ret) + goto errout_free; st_map->image = arch_alloc_bpf_trampoline(PAGE_SIZE); if (!st_map->image) { @@ -719,24 +741,30 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) * here. */ bpf_jit_uncharge_modmem(PAGE_SIZE); - __bpf_struct_ops_map_free(map); - return ERR_PTR(-ENOMEM); + ret = -ENOMEM; + goto errout_free; } st_map->uvalue = bpf_map_area_alloc(vt->size, NUMA_NO_NODE); st_map->links = bpf_map_area_alloc(btf_type_vlen(t) * sizeof(struct bpf_links *), NUMA_NO_NODE); if (!st_map->uvalue || !st_map->links) { - __bpf_struct_ops_map_free(map); - return ERR_PTR(-ENOMEM); + ret = -ENOMEM; + goto errout_free; } - - st_map->btf = btf_vmlinux; + st_map->btf = btf; mutex_init(&st_map->lock); bpf_map_init_from_attr(map, attr); return map; + +errout_free: + __bpf_struct_ops_map_free(map); +errout: + btf_put(btf); + + return ERR_PTR(ret); } static u64 bpf_struct_ops_map_mem_usage(const struct bpf_map *map) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 54a97c269e7a..935a0e209ac9 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1128,7 +1128,7 @@ static bool bpf_net_capable(void) return capable(CAP_NET_ADMIN) || capable(CAP_SYS_ADMIN); } -#define BPF_MAP_CREATE_LAST_FIELD map_token_fd +#define BPF_MAP_CREATE_LAST_FIELD value_type_btf_obj_fd /* called via syscall */ static int map_create(union bpf_attr *attr) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 52c530b5733c..970b601ac2ba 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20086,6 +20086,7 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) const struct btf_member *member; struct bpf_prog *prog = env->prog; u32 btf_id, member_idx; + struct btf *btf; const char *mname; if (!prog->gpl_compatible) { @@ -20093,8 +20094,10 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) return -EINVAL; } + btf = prog->aux->attach_btf ?: bpf_get_btf_vmlinux(); + btf_id = prog->aux->attach_btf_id; - st_ops_desc = bpf_struct_ops_find(btf_vmlinux, btf_id); + st_ops_desc = bpf_struct_ops_find(btf, btf_id); if (!st_ops_desc) { verbose(env, "attach_btf_id %u is not a supported struct\n", btf_id); @@ -20111,8 +20114,8 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) } member = &btf_type_member(t)[member_idx]; - mname = btf_name_by_offset(btf_vmlinux, member->name_off); - func_proto = btf_type_resolve_func_ptr(btf_vmlinux, member->type, + mname = btf_name_by_offset(btf, member->name_off); + func_proto = btf_type_resolve_func_ptr(btf, member->type, NULL); if (!func_proto) { verbose(env, "attach to invalid member %s(@idx %u) of struct %s\n", diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 7ab00babcccc..d72a16adfbb3 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1438,6 +1438,11 @@ union bpf_attr { */ __u64 map_extra; __u32 map_token_fd; + + __u32 value_type_btf_obj_fd; /* fd pointing to a BTF + * type data for + * btf_vmlinux_value_type_id. + */ }; struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */