From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f169.google.com (mail-yw1-f169.google.com [209.85.128.169]) (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 7F0CB4A997 for ; Wed, 20 Dec 2023 22:27:08 +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="K5lYmRFi" Received: by mail-yw1-f169.google.com with SMTP id 00721157ae682-5e54d40cca2so1876557b3.3 for ; Wed, 20 Dec 2023 14:27:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1703111227; x=1703716027; 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=7i7nUoAkkd694ijbCLduicVJ3KrFCpRdUkUsCCEao88=; b=K5lYmRFi8KlinQZimUIVBZALpnyefXOxIArbBg78WveNrJMmJFdax1+86I0XcdRcnY 3PslBswB/t8T7PDWIOeSwyghvURM3He27eiIbd+vtAPEjyGhymZOmKHKTLVuWvmTQ42j lsjnf82hjphhhnlrLIM0b0zUpAWL2yxXx+LfBgTafPU5o05Tvswe6UHO084LU60+7KzE ypvVrTQY3+i4KpOeE8erA/OXPYsivK0rje6Y28mhKG0NcE4H1MmdZiAkJIt54wEVUfuu Sjvz3jmaiw7t/6Do9bLIaGb1PfxtXAU5benoT1HyRFNG4p3/d6w1L67nualtvo0v0A0+ hgoQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703111227; x=1703716027; 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=7i7nUoAkkd694ijbCLduicVJ3KrFCpRdUkUsCCEao88=; b=nVsRUWx/d1pCUcmLSLfQ4u9bIiQpj8UZY/0CuhzeiS9U8uUH4/Yq8fCe9ZCev+KZZ8 0tWjYRILuQV/WK/e08sZzzcIuNBWhq3rWoy/jR24mF9kmjH3M0WAGLnRr+hN47sibfet loQSPrTZS+aksDzG7NdeDwd9e8E6QSO3awZvIsAlZedg7qCBI3W9OT1+sPo+vedaWYqb AMxzQH6J5+o5hK7xqpi2FsWP3O4D1wiX3DDpaM13bN8w0jXsp1eoAtDdTnjlw66c38hZ N60rsZnEqd/B8BZJwpiVvqFnC2u3XH+Qu7URwyPqwC0IHUW1ylsk/4Mmx5BlW3NbBaKf eVXw== X-Gm-Message-State: AOJu0Yyp+VQAzho5IIjAnu13LqC7Wj53mYQ30FNXaqx3IJDxsosxGb5I e8CdHrlkWrQeoLV01uyJSevKPrZhjcU= X-Google-Smtp-Source: AGHT+IGfHQHAV/IZzDV+8MYjVtKgFZDQXeod/HOKW+OInDK5i0R9/OOEV6gdytLGieFMpT3/rXxBFQ== X-Received: by 2002:a81:4942:0:b0:5e7:8d32:dbdb with SMTP id w63-20020a814942000000b005e78d32dbdbmr290653ywa.82.1703111227189; Wed, 20 Dec 2023 14:27:07 -0800 (PST) Received: from kickker.attlocal.net ([2600:1700:6cf8:1240:8cc1:afcb:3651:3dad]) by smtp.gmail.com with ESMTPSA id m125-20020a0dfc83000000b005ca4e49bb54sm284304ywf.142.2023.12.20.14.27.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Dec 2023 14:27:06 -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 v15 08/14] bpf: pass attached BTF to the bpf_struct_ops subsystem Date: Wed, 20 Dec 2023 14:26:48 -0800 Message-Id: <20231220222654.1435895-9-thinker.li@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231220222654.1435895-1-thinker.li@gmail.com> References: <20231220222654.1435895-1-thinker.li@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 8eb949b52102..1b5bf5d60e38 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1403,6 +1403,11 @@ union bpf_attr { * to using 5 hash functions). */ __u64 map_extra; + + __s32 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 7505f515aac3..71cd433fc521 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 >= 0) { + /* 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 44b07a08295c..bae096964930 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1123,7 +1123,7 @@ static int map_check_btf(struct bpf_map *map, const struct btf *btf, return ret; } -#define BPF_MAP_CREATE_LAST_FIELD map_extra +#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 dafcd34be56b..822bb4f5e8a6 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20219,6 +20219,7 @@ 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) { @@ -20226,8 +20227,10 @@ 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); @@ -20244,8 +20247,8 @@ 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 1949d881f230..118247962b73 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1403,6 +1403,11 @@ union bpf_attr { * to using 5 hash functions). */ __u64 map_extra; + + __s32 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 */ -- 2.34.1