From patchwork Sun Oct 22 05:03:31 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: 13431635 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 E38EC17E6 for ; Sun, 22 Oct 2023 05:03:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="jdUAtTQT" Received: from mail-yw1-x112c.google.com (mail-yw1-x112c.google.com [IPv6:2607:f8b0:4864:20::112c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 499CE124 for ; Sat, 21 Oct 2023 22:03:55 -0700 (PDT) Received: by mail-yw1-x112c.google.com with SMTP id 00721157ae682-5a7be88e9ccso23273347b3.2 for ; Sat, 21 Oct 2023 22:03:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1697951034; x=1698555834; 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=EFGNJIKyLlK+zlHfxbHJFmSQZeBqEpwSA0br+5DVEHY=; b=jdUAtTQTCPwYJOdL3WkwGc8EtVO5Fj72E+BvjmqWGxvRaeYwxGhNrcFFjULA52y86i bIj5IBylRUSQCKjoKB34iMKntKzkjty1yL64K+6azoK2Mz8428NjkVAoieGl0xX7NVhh ty0b2R0fjOv/B8kvzSlS4BDHIXczDpXDVr3dlHFrV53TmHrmp83gnog3shULDphNVtlo SeU77ZFNVekswAzsnQX0fiV6JO/PfpMMCVgL4PlgI2G0NAHEyubNgasVjKlXU6Czg98l dOjpPNBtz8iC8Hpv6sgermxEa6aCX01aci7S2N7Mrse7+X4iFPdEtJVgNgy6HOBLu4Yy AlFQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1697951034; x=1698555834; 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=EFGNJIKyLlK+zlHfxbHJFmSQZeBqEpwSA0br+5DVEHY=; b=WX5rmmyVus6+2oesVl4fixS9dagnJR/hGg6kU5ygtfBnpPvcjE6pvV2FzkB+wmAsIH 8Wn6usQeAUI5dGf/SOssbxcEmiAzz8RtrxgvCWLb0Q6Q1hap3cp7Cfy3eYG3tq0mvyf2 d4agALltUJF15N0yUQao+WpO/ITrVGxayjZQ4dHzvIZtMNfKDzZNuweoi2QdXKHSOlg5 qJHNblPhB0Ndq8gV/WndH0nGitBM6PIodnxGm7O+2lMkcYQLAyWlXRZbmeKTH1jRtVxT aI9WUrdhvd6jhQFHdI3KOqZMVTobqPd9AIMD+wwk92PQ6PmT9AZFD7sUxn435JkuV5BH Zotw== X-Gm-Message-State: AOJu0YzlACljLsnkKtsSKqqJvblp7rWAa9vud3Q5OJjRECNf4UwrZ8H4 C8L0QLxHruIBBPh2dwtBEw6kwujWGoA= X-Google-Smtp-Source: AGHT+IF6oUD8YsvqbyuiUAe/96Tt6W67fpJ1QZaMxe51dioDKva+eFvv1nlW4BJQ5HIlcTVNMj4lXw== X-Received: by 2002:a05:690c:d8f:b0:5a7:c92b:f49 with SMTP id da15-20020a05690c0d8f00b005a7c92b0f49mr7925507ywb.21.1697951034226; Sat, 21 Oct 2023 22:03:54 -0700 (PDT) Received: from kickker.attlocal.net ([2600:1700:6cf8:1240:9904:3214:88c1:e733]) by smtp.gmail.com with ESMTPSA id j1-20020a0de001000000b005a8c392f498sm2035169ywe.82.2023.10.21.22.03.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 21 Oct 2023 22:03:53 -0700 (PDT) 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 v6 06/10] bpf: pass attached BTF to the bpf_struct_ops subsystem Date: Sat, 21 Oct 2023 22:03:31 -0700 Message-Id: <20231022050335.2579051-7-thinker.li@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231022050335.2579051-1-thinker.li@gmail.com> References: <20231022050335.2579051-1-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 Giving a BTF, the bpf_struct_ops knows the right place to look up type info associated with a type ID. This enables a user space program to load a struct_ops object linked to a struct_ops type defined by a module, by providing the module BTF (fd). The bpf_prog includes attach_btf in aux which is passed along with the bpf_attr when loading the program. The purpose of attach_btf is to determine the btf type of attach_btf_id. The attach_btf_id is then used to identify the traced function for a trace program. In the case of struct_ops programs, it is used to identify the struct_ops type of the struct_ops object that a program is attached to. Signed-off-by: Kui-Feng Lee --- include/linux/bpf_verifier.h | 1 + include/uapi/linux/bpf.h | 5 +++++ kernel/bpf/bpf_struct_ops.c | 32 +++++++++++++++++++++++++------- kernel/bpf/syscall.c | 2 +- kernel/bpf/verifier.c | 15 ++++++++++++++- tools/include/uapi/linux/bpf.h | 5 +++++ 6 files changed, 51 insertions(+), 9 deletions(-) diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 94ec766432f5..5dc4d5fd8ab5 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -579,6 +579,7 @@ struct bpf_verifier_env { u32 prev_insn_idx; struct bpf_prog *prog; /* eBPF program being verified */ const struct bpf_verifier_ops *ops; + struct module *attach_btf_mod; /* The owner module of prog->aux->attach_btf */ struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */ int stack_size; /* number of states to be processed */ bool strict_alignment; /* perform strict pointer alignment checks */ diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 73b155e52204..b5ef22f65f35 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1390,6 +1390,11 @@ 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 6367d42b2ce1..99ab61cc6cad 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -694,6 +694,7 @@ 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->st_ops_desc->btf); bpf_map_area_free(st_map); } @@ -735,16 +736,31 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) const struct btf_type *t, *vt; struct module *mod = NULL; 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)); + + if (btf != btf_vmlinux) { + mod = btf_try_get_module(btf); + if (!mod) { + ret = -EINVAL; + goto errout; + } + } + } else { + btf = btf_vmlinux; + btf_get(btf); + } - if (st_ops_desc->btf != btf_vmlinux) { - mod = btf_try_get_module(st_ops_desc->btf); - if (!mod) - return ERR_PTR(-EINVAL); + 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; @@ -805,7 +821,9 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) __bpf_struct_ops_map_free(map); btf = NULL; /* has been released */ errout: + btf_put(btf); module_put(mod); + return ERR_PTR(ret); } diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 85c1d908f70f..5daf8a2c2bba 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1097,7 +1097,7 @@ 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 7d0cf7289092..0289574bb0d5 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -19624,6 +19624,7 @@ 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) { @@ -19631,8 +19632,18 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) return -EINVAL; } + btf = prog->aux->attach_btf; + if (btf != btf_vmlinux) { + /* Make sure st_ops is valid through the lifetime of env */ + env->attach_btf_mod = btf_try_get_module(btf); + if (!env->attach_btf_mod) { + verbose(env, "owner module of btf is not found\n"); + return -ENOTSUPP; + } + } + 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); @@ -20343,6 +20354,8 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3 env->prog->expected_attach_type = 0; *prog = env->prog; + + module_put(env->attach_btf_mod); err_unlock: if (!is_priv) mutex_unlock(&bpf_verifier_lock); diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 73b155e52204..b5ef22f65f35 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1390,6 +1390,11 @@ 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 */