From patchwork Fri Oct 27 20:52:23 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: 13439154 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 4AE4A3F4D5 for ; Fri, 27 Oct 2023 20:52:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="MDvi5IL4" Received: from mail-yw1-x112f.google.com (mail-yw1-x112f.google.com [IPv6:2607:f8b0:4864:20::112f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C523A1B5 for ; Fri, 27 Oct 2023 13:52:42 -0700 (PDT) Received: by mail-yw1-x112f.google.com with SMTP id 00721157ae682-5afb93d310fso7922807b3.3 for ; Fri, 27 Oct 2023 13:52:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1698439962; x=1699044762; 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=EdoKgDbw0RPOGc9eKfRxQYiqQHGExsmimc986Jd4TTw=; b=MDvi5IL4lj4k5m2UrWj/KK+SIMgzMHrxjmz87sPBcg2Z7m0l7L2b66u77NuN1QpUsj hXj7Bi4MwSHMtYKNHGj0xR1NewZLazfEotXpSETH4/t934ULuHqva4GE63Fmi5FjEaq+ X3vDT5dYtgJGwTJkZzstX8neOoZRNhPka+Ryh72j5IDN/cdJ9PxFW5Z4ksgIFDkZW3wx hvqvYloS04N/iyA1toBRswn6cyjTb96wKTRKw2bVz/5M1nylgi6NdMxvqD/ey/wQ1uwK Gpy40K4fXAr3AP3jatStNA2podBQm4DnOPC0bJhDt4Y8llT1dfRCFvUBPgbHLvGh/VAn 6gtA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698439962; x=1699044762; 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=EdoKgDbw0RPOGc9eKfRxQYiqQHGExsmimc986Jd4TTw=; b=A7nbwCtMghZN3+U+11wFt8UAowldS42tTHW885XeGcxDrz54By7K4+HdQoA0qnd1pU mLt7AEB86P+3lvLdeqFwrhmPUQG5d9NcNMlY2g500LnosXE0LCivPHWLmUq/P/BehTsw HdByb6Q/Z4S1LmDYj94lfkeexDsfBCHmZGfyFzghS6CZ8sbsXbJmjDygQcnSUk8GmIbM yrdeaQS/4fO5LzEBbvkjRRN2NdL+6pWpAe4cEgInsxILR1wXYe/v5YBio0fYw/d+oHwL e5vYp4y1cx3SdPxTEfFdArroe2G8qb1VSmp1AKpq4hMUZFIUaCH0V3x3bXZShhJwUOaS UGyg== X-Gm-Message-State: AOJu0YxYp5g0d6ZN25QdQS2FJ1iZXFd/Es3Qv9iAAKnSjD2dXiazHZyj lqMZjq5BCdSnrFBfVlswDHDWy3q7wRs= X-Google-Smtp-Source: AGHT+IHgIxqBiJmTIdjNaaJbr+yaz4g6kx9Y5yXsGA8GiTFh5KtXbcFBw0TUgnvDLk6Qr2BmvZkM5w== X-Received: by 2002:a81:ac4b:0:b0:5a7:b10c:4772 with SMTP id z11-20020a81ac4b000000b005a7b10c4772mr4565838ywj.19.1698439961726; Fri, 27 Oct 2023 13:52:41 -0700 (PDT) Received: from kickker.attlocal.net ([2600:1700:6cf8:1240:41cd:a94b:292d:cd8]) by smtp.gmail.com with ESMTPSA id c125-20020a0df383000000b005a7d50b7edfsm1048737ywf.142.2023.10.27.13.52.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Oct 2023 13:52:41 -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 v7 06/10] bpf: pass attached BTF to the bpf_struct_ops subsystem Date: Fri, 27 Oct 2023 13:52:23 -0700 Message-Id: <20231027205227.855463-7-thinker.li@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231027205227.855463-1-thinker.li@gmail.com> References: <20231027205227.855463-1-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 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 256516aba632..db2bbba50e38 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 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..d03b39fb0faa 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); @@ -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 */