From patchwork Thu Dec 7 01:39:43 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: 13482556 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="g7mmgInD" Received: from mail-yw1-x1132.google.com (mail-yw1-x1132.google.com [IPv6:2607:f8b0:4864:20::1132]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B30581A5 for ; Wed, 6 Dec 2023 17:40:14 -0800 (PST) Received: by mail-yw1-x1132.google.com with SMTP id 00721157ae682-5d34f8f211fso1689687b3.0 for ; Wed, 06 Dec 2023 17:40:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1701913213; x=1702518013; 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=Fzh1eQX9qmrl8ZPxxUEtcmZnUDxIGpXg8T7pQMr7Xc4=; b=g7mmgInDNuuB1LtOPzgiaZ5IU+6CMe/ei1Nedt8pOAe0G5LseqAl2X60ZUMawYfVkp gD/iAuBKRN3AMLAmYFMXQ2xraBhut7ulzcxQegsVWDqJ/8bhFwLHMisZeC6icv3IOzXS GSAaIMf9gw9h/UCs0F5DwJj2NzO/MbKlO17Pydq+6EL882iCv5Hm4VjOSpib0wWWq6Nq jyvr/X6PHvpg3lUyn01+wkFNcOcsPoxt4Oiw75kyQuoIAx9mJ2hJBIoYMmqbXUB0dwk1 ZgqE9Up4IZ1FBjEohhvOOEVijOaZu1HRDh1K6dDkO85ykOPaxaHq8LnXZVvNlDWr/Y9a lgmQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701913213; x=1702518013; 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=Fzh1eQX9qmrl8ZPxxUEtcmZnUDxIGpXg8T7pQMr7Xc4=; b=oAgqNtqq2K5UzUtd6O57IEQSYFR8udmM7xcvy78lKk1+Dd/iiHPk3His764PT1oqkm qyaF319l/dIZWMa6Q0vZfPq/EGVNdFVBecOZTV3F2C4UouEe7QAcYLoKbWMhiSvWqcqW KupQKtqeBNC4H3DuhGVX7MKZThK9csBRDzsgMq+q00Q6vnNctCHX9JqDLpMXZcE29CKg i7DFQnE+pHalUxPfvEmKKzs143IpjL++w35pwWVCcqRIbJ1Xeey5obG5WTq7QaczGi8x aFEc2L5poyB2KW/QQM8iTUrbMEBvZae5ZlpZ5E0lSwRLZwg+Qc5MWctEjUZavmx1ioXm nMjA== X-Gm-Message-State: AOJu0YzpQUMV2xUg+/+rdU0bHI41PJVts6Q4LHme2SiUwoD7OWtI/5CT wyvxWr80/gzQ4Y4qzs0E0i2bxN0jpXs= X-Google-Smtp-Source: AGHT+IE2DH3xOko5XqayrkqJNoHpOQEXEbwJH7rNltnG5rZFzKwg0kPBrnfGE8zqk8yZ3Xw0HpiDAA== X-Received: by 2002:a05:690c:c:b0:5d7:ca4a:b1e1 with SMTP id bc12-20020a05690c000c00b005d7ca4ab1e1mr2233409ywb.73.1701913213308; Wed, 06 Dec 2023 17:40:13 -0800 (PST) Received: from kickker.attlocal.net ([2600:1700:6cf8:1240:c8f2:3a3b:3003:f559]) by smtp.gmail.com with ESMTPSA id v134-20020a81488c000000b005d997db3b2fsm60768ywa.23.2023.12.06.17.40.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Dec 2023 17:40:12 -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 v12 07/14] bpf: pass attached BTF to the bpf_struct_ops subsystem Date: Wed, 6 Dec 2023 17:39:43 -0800 Message-Id: <20231207013950.1689269-8-thinker.li@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231207013950.1689269-1-thinker.li@gmail.com> References: <20231207013950.1689269-1-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 e88746ba7d21..8e5a188e2883 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1401,6 +1401,11 @@ union bpf_attr { * to using 5 hash functions). */ __u64 map_extra; + + __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 123ec76c48a9..3f647df50504 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -635,6 +635,7 @@ 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); } @@ -675,15 +676,30 @@ 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; @@ -694,17 +710,17 @@ 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 = bpf_jit_alloc_exec(PAGE_SIZE); if (!st_map->image) { @@ -713,25 +729,31 @@ 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); set_vm_flush_reset_perms(st_map->image); 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 5e43ddd1b83f..6df7edc4b5e3 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1096,7 +1096,7 @@ 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 405aeee608aa..fccdab9db9ed 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20012,6 +20012,7 @@ 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) { @@ -20019,8 +20020,10 @@ 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); @@ -20037,8 +20040,8 @@ 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 e88746ba7d21..8e5a188e2883 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1401,6 +1401,11 @@ union bpf_attr { * to using 5 hash functions). */ __u64 map_extra; + + __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 */