From patchwork Wed Nov 1 20:45:15 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: 13443053 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 6BFEF12E44 for ; Wed, 1 Nov 2023 20:45:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="AepvU5qf" Received: from mail-yb1-xb32.google.com (mail-yb1-xb32.google.com [IPv6:2607:f8b0:4864:20::b32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 335C010C for ; Wed, 1 Nov 2023 13:45:36 -0700 (PDT) Received: by mail-yb1-xb32.google.com with SMTP id 3f1490d57ef6-d9fe0a598d8so190011276.2 for ; Wed, 01 Nov 2023 13:45:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1698871535; x=1699476335; 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=tynuz0fgTYxbBl2yuhgxDz0ux4d0VWM4jwwcy6q2XJs=; b=AepvU5qfMlYUJk7gYCi2GsvJUL3nxzKe/l3SazJUUZwna6Ft4zOS0Akx8yNVkBPxEA o3GpYE5YFaZnGj+Z2llCI2jiFTLxVyTgqEY6drGATpQdy02w8+pLJVCmm718PiVD0vnt aDYHC5jT0Ia1h32EQLqaSUxkWd6mwMEUpz+dKLuqRXf0jobUUw5W5KtvUsd5u2lstqX6 BGqKHx4T+f2k75MHVBC3uvEZL8HJU4JtDcEQ7zoIjqJCmELOmsXlpyH1+vFg2msln4dF PJQGPFikjA25dErszAfisG5nTv6/asnUAiSEtPB6S5jvGw9kMkuqPM1F0ZIufKYpTLUZ gAsw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698871535; x=1699476335; 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=tynuz0fgTYxbBl2yuhgxDz0ux4d0VWM4jwwcy6q2XJs=; b=TrIepU5E/Bb0fNdF//Codu2Rd1bPb90twarqLqzR7Q4bi4TvvBipwJgMd/8NUD2jXh c5TCsJxdBbOjUvK487sApypPZqoSZIsBeiolRQNYTquZ/5WR/faNM9dYWyzEQfXyb1u3 3lVW3O4JDXr7b51Xjz/1Qlk+uielPZVxji5gU/379m0DAG3ObDODz9IV6WYL2C9W0/3H nZ6Rl7qOb5D03ZLZP84T1+4+V7ueKOemYpYupaI1hUOT1T8qJd+6mtVb0OOKyxAltrgI OLtMYue4jo4+vb4pSTsMNbfFCqLaX+ujwMrluxK+TfnCpL/vvlI4evt8aIgFqPMNtZvA XeXQ== X-Gm-Message-State: AOJu0YwdM+JykHmDBwt30sHBz74DjxY9L6DzsN239fNBUsDROduxYHTn HKznEko5DU/oZ8w+zLWwJQ4ulBFOBDw= X-Google-Smtp-Source: AGHT+IFBoFRWe+8Hr9tfdHnt86CYSlBrhrkp9+ROG2nfVxRAszjNcDu9yi8fQPfc0ZlLETm55J9ASw== X-Received: by 2002:a25:e74b:0:b0:d9a:ee0c:d444 with SMTP id e72-20020a25e74b000000b00d9aee0cd444mr13546658ybh.43.1698871534784; Wed, 01 Nov 2023 13:45:34 -0700 (PDT) Received: from kickker.attlocal.net ([2600:1700:6cf8:1240:eea0:6f66:c57d:6b7c]) by smtp.gmail.com with ESMTPSA id o83-20020a25d756000000b00da086d6921fsm342386ybg.50.2023.11.01.13.45.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Nov 2023 13:45:34 -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 v9 08/12] bpf: pass attached BTF to the bpf_struct_ops subsystem Date: Wed, 1 Nov 2023 13:45:15 -0700 Message-Id: <20231101204519.677870-9-thinker.li@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231101204519.677870-1-thinker.li@gmail.com> References: <20231101204519.677870-1-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 Every kernel module has its BTF, comprising information on types defined in the module. The BTF fd (attr->value_type_btf_obj_fd) passed from userspace helps the bpf_struct_ops to lookup type information and description of the struct_ops type, which is necessary for parsing the layout of map element values and registering maps. The descriptions are looked up by matching a type id (attr->btf_vmlinux_value_type_id) against bpf_struct_ops_desc(s) defined in a BTF. If the struct_ops type is defined in a module, the bpf_struct_ops needs to know the module BTF to lookup the bpf_struct_ops_desc. 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 | 36 +++++++++++++++++++++++++--------- kernel/bpf/syscall.c | 2 +- kernel/bpf/verifier.c | 19 +++++++++++++++--- tools/include/uapi/linux/bpf.h | 5 +++++ 6 files changed, 55 insertions(+), 13 deletions(-) diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 24213a99cc79..c1461342f19e 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -598,6 +598,7 @@ 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 0f6cdf52b1da..fd20c52606b2 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1398,6 +1398,11 @@ 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 bc855b2ef97e..2d853431bf09 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -677,6 +677,7 @@ 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); } @@ -718,16 +719,31 @@ 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; @@ -750,6 +766,7 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) goto errout; } + st_map->btf = btf; st_map->st_ops_desc = st_ops_desc; map = &st_map->map; @@ -776,8 +793,6 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) goto errout_free; } - st_map->btf = btf_vmlinux; - mutex_init(&st_map->lock); set_vm_flush_reset_perms(st_map->image); bpf_map_init_from_attr(map, attr); @@ -788,8 +803,11 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) errout_free: __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 0ed286b8a0f0..974651fe2bee 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 bdd166cab977..20d6d9665983 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 +20094,18 @@ 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); @@ -20111,8 +20122,8 @@ 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", @@ -20805,6 +20816,8 @@ 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 0f6cdf52b1da..fd20c52606b2 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1398,6 +1398,11 @@ 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 */