From patchwork Sat Dec 9 00:27:02 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: 13485908 X-Patchwork-Delegate: bpf@iogearbox.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="V7xacn01" Received: from mail-yw1-x112e.google.com (mail-yw1-x112e.google.com [IPv6:2607:f8b0:4864:20::112e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 21A9C1729 for ; Fri, 8 Dec 2023 16:27:22 -0800 (PST) Received: by mail-yw1-x112e.google.com with SMTP id 00721157ae682-5d05ff42db0so24685497b3.2 for ; Fri, 08 Dec 2023 16:27:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1702081641; x=1702686441; 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=Ub9qoi3PTEGZNBq4TRs3aeMktswSheoGW49AGywpBTQ=; b=V7xacn01tLgZFAaTEc85s+ohGFiLaOjvvOkWbYgI/IzrM3rPkIoSx1LTP+aVwcbCHw rx0U905QilvIq+GelHsgcfJEqupncDh/YQ5fX8uuC3wQAgtCDFL2KZICjS4Ql8Hpixxc kKzwxHA2JhF4sto+wGsEGLNpA+A6XVhrtGcIjmuyFrAPJabKgKJRiYkLpkRfYRRlx4Hg d0o31jYSzbg+RESFROaLWUM80T6d5oetIRaUFWQCSlAtOuHpV6mScXAHQQclLWEUD5O4 lHobCJKZuviR27jWdy9yPctC+nn7ynyjP5vAJNWltH5v6642+VH16J+z4e7PeF3K8mM6 t8uQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702081641; x=1702686441; 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=Ub9qoi3PTEGZNBq4TRs3aeMktswSheoGW49AGywpBTQ=; b=tSfq+WhgAj9e9KTcKy2pF014ZUyT87OKxw++94sekHM82sYB3C/xcqVVG99JCJcnWN 8LrBc7gBYjIB0vGSINI+I0ewZ8lrxbdTnOyjsnVDnetkB8AjFQqBusa0+6EI0uTKk0oq 3lGgaw8QzyhyZtVaVjRfdgUI0HxqJoEop8qBNac+8byH9OxxAu9hS1Nv6R+gYZQGo5LP 6lSLiqAsW3fPQnnwMVJGGgfB3zk3EBTyA+AZ2PKNCT+gaXSoc1gR3q1NiwlYdVDNGVd8 l2UuwMWH8DXVcZWIaAkFdQXaDnljESUekqBt2uEG1eR5T0Nijm8iv/Ft/20wyxoomnum 1SEA== X-Gm-Message-State: AOJu0YzybBhxgnvnvEV5nMy+/7QDsHuvtG7GkvQsBE+OtH9Lr6R044At Q/mD8JZCu1M2CKAhkg+igbJn1DEP7rvUgg== X-Google-Smtp-Source: AGHT+IGJKpJZfW1G1bRUXimEFHHbwnp8/DBBrrJ2f06Tj4VDXOvLxKse9cb1canzuAEbIOSD4MBeQg== X-Received: by 2002:a0d:d4d0:0:b0:5cc:dcf:47a4 with SMTP id w199-20020a0dd4d0000000b005cc0dcf47a4mr890301ywd.40.1702081641057; Fri, 08 Dec 2023 16:27:21 -0800 (PST) Received: from kickker.attlocal.net ([2600:1700:6cf8:1240:65fe:fe26:c15:a05c]) by smtp.gmail.com with ESMTPSA id v4-20020a818504000000b005d9729068f5sm1057450ywf.42.2023.12.08.16.27.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Dec 2023 16:27:20 -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 v13 07/14] bpf: pass attached BTF to the bpf_struct_ops subsystem Date: Fri, 8 Dec 2023 16:27:02 -0800 Message-Id: <20231209002709.535966-8-thinker.li@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231209002709.535966-1-thinker.li@gmail.com> References: <20231209002709.535966-1-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 | 56 +++++++++++++++++++++++----------- kernel/bpf/syscall.c | 2 +- kernel/bpf/verifier.c | 9 ++++-- tools/include/uapi/linux/bpf.h | 5 +++ 5 files changed, 56 insertions(+), 21 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index e0545201b55f..5c3838a97554 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 ed4d84a8437c..f943f8378e76 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 +682,30 @@ 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_PTR(PTR_ERR(btf)); + } else { + btf = btf_vmlinux; + 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 +716,17 @@ 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 +735,30 @@ 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 aff045eed375..4aced7e58904 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1126,7 +1126,7 @@ 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 6b45f56f8d4c..795c16f9cf57 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20070,6 +20070,7 @@ 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) { @@ -20077,8 +20078,10 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) return -EINVAL; } + btf = prog->aux->attach_btf; + 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); @@ -20095,8 +20098,8 @@ 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 e0545201b55f..5c3838a97554 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 */