From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 77E7AC3 for ; Mon, 4 Dec 2023 15:40:09 -0800 (PST) Received: from pps.filterd (m0089730.ppops.net [127.0.0.1]) by m0089730.ppops.net (8.17.1.19/8.17.1.19) with ESMTP id 3B4MQC8Z020118 for ; Mon, 4 Dec 2023 15:40:08 -0800 Received: from maileast.thefacebook.com ([163.114.130.16]) by m0089730.ppops.net (PPS) with ESMTPS id 3us9fbxxbs-17 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 04 Dec 2023 15:40:08 -0800 Received: from twshared51573.38.frc1.facebook.com (2620:10d:c0a8:1b::2d) by mail.thefacebook.com (2620:10d:c0a8:82::b) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.34; Mon, 4 Dec 2023 15:39:53 -0800 Received: by devbig019.vll3.facebook.com (Postfix, from userid 137359) id 652DE3C972657; Mon, 4 Dec 2023 15:39:49 -0800 (PST) From: Andrii Nakryiko To: , , , CC: , Subject: [PATCH bpf-next 07/13] bpf: prepare btf_prepare_func_args() for handling static subprogs Date: Mon, 4 Dec 2023 15:39:25 -0800 Message-ID: <20231204233931.49758-8-andrii@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231204233931.49758-1-andrii@kernel.org> References: <20231204233931.49758-1-andrii@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-ORIG-GUID: jwjE1z16mJBIt1pBpGXwRDRduRNoWyec X-Proofpoint-GUID: jwjE1z16mJBIt1pBpGXwRDRduRNoWyec X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.997,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-12-04_22,2023-12-04_01,2023-05-22_02 Generalize btf_prepare_func_args() to support both global and static subprogs. We are going to utilize this property in the next patch, reusing btf_prepare_func_args() for subprog call logic instead of reparsing BTF information in a completely separate implementation. btf_prepare_func_args() now detects whether subprog is global or static makes slight logic adjustments for static func cases, like not failing fatally (-EFAULT) for conditions that are allowable for static subprogs. Somewhat subtle (but major!) difference is the handling of pointer argume= nts. Both global and static functions need to handle special context arguments (which are pointers to predefined type names), but static subprogs give up on any other pointers, falling back to marking subprog as "unreliable", disabling the use of BTF type information altogether. For global functions, though, we are assuming that such pointers to unrecognized types are just pointers to fixed-sized memory region (or error out if size cannot be established, like for `void *` pointers). This patch accommodates these small differences and sets up a stage for refactoring in the next patch, eliminating a separate BTF-based parsing logic in btf_check_func_arg_match(). Signed-off-by: Andrii Nakryiko --- include/linux/bpf_verifier.h | 5 +++++ kernel/bpf/btf.c | 18 +++++++++--------- kernel/bpf/verifier.c | 5 ----- 3 files changed, 14 insertions(+), 14 deletions(-) diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 23d054c9d1c8..45eb7b5e4601 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -701,6 +701,11 @@ struct bpf_verifier_env { char tmp_str_buf[TMP_STR_BUF_LEN]; }; =20 +static inline struct bpf_func_info_aux *subprog_aux(struct bpf_verifier_= env *env, int subprog) +{ + return &env->prog->aux->func_info_aux[subprog]; +} + static inline struct bpf_subprog_info *subprog_info(struct bpf_verifier_= env *env, int subprog) { return &env->subprog_info[subprog]; diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index bd430a8b842e..525ba044e967 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6913,6 +6913,7 @@ int btf_check_subprog_call(struct bpf_verifier_env = *env, int subprog, */ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) { + bool is_global =3D subprog_aux(env, subprog)->linkage =3D=3D BTF_FUNC_G= LOBAL; struct bpf_subprog_info *sub =3D subprog_info(env, subprog); struct bpf_verifier_log *log =3D &env->log; struct bpf_prog *prog =3D env->prog; @@ -6926,14 +6927,15 @@ int btf_prepare_func_args(struct bpf_verifier_env= *env, int subprog) if (sub->args_cached) return 0; =20 - if (!prog->aux->func_info || - prog->aux->func_info_aux[subprog].linkage !=3D BTF_FUNC_GLOBAL) { + if (!prog->aux->func_info) { bpf_log(log, "Verifier bug\n"); return -EFAULT; } =20 btf_id =3D prog->aux->func_info[subprog].type_id; if (!btf_id) { + if (!is_global) /* not fatal for static funcs */ + return -EINVAL; bpf_log(log, "Global functions need valid BTF\n"); return -EFAULT; } @@ -6989,16 +6991,14 @@ int btf_prepare_func_args(struct bpf_verifier_env= *env, int subprog) sub->args[i].arg_type =3D ARG_SCALAR; continue; } - if (btf_type_is_ptr(t)) { + if (btf_type_is_ptr(t) && btf_get_prog_ctx_type(log, btf, t, prog_type= , i)) { + sub->args[i].arg_type =3D ARG_PTR_TO_CTX; + continue; + } + if (is_global && btf_type_is_ptr(t)) { u32 mem_size; =20 - if (btf_get_prog_ctx_type(log, btf, t, prog_type, i)) { - sub->args[i].arg_type =3D ARG_PTR_TO_CTX; - continue; - } - t =3D btf_type_skip_modifiers(btf, t->type, NULL); - ref_t =3D btf_resolve_size(btf, t, &mem_size); if (IS_ERR(ref_t)) { bpf_log(log, diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 642260d277ce..2e74bc90adf3 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -437,11 +437,6 @@ static const char *subprog_name(const struct bpf_ver= ifier_env *env, int subprog) return btf_type_name(env->prog->aux->btf, info->type_id); } =20 -static struct bpf_func_info_aux *subprog_aux(const struct bpf_verifier_e= nv *env, int subprog) -{ - return &env->prog->aux->func_info_aux[subprog]; -} - static void mark_subprog_exc_cb(struct bpf_verifier_env *env, int subpro= g) { struct bpf_subprog_info *info =3D subprog_info(env, subprog); --=20 2.34.1