From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5686C5DF61 for ; Thu, 7 Nov 2019 05:47:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A04E1214D8 for ; Thu, 7 Nov 2019 05:47:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573105674; bh=GjvNngsw2TczZdK3NF7xHIGPm5Xcvunkjv06NpF4DD4=; h=From:To:CC:Subject:Date:In-Reply-To:References:List-ID:From; b=GKUN+/lxB2JnkTzmRNuJW+2gr5v8V0y/HpvwAN8YLaJdKp9SC3cBmClviQ+cdLmwV fdw8TY89yR5k8WMgDHoYHyQMYnbSWaQUkMQOw/UnpTV6rOCO0ZMyFaKasB6VzQIRTX sPpkehaVwtYs7tuHJDSmL+ZYsMEuF81ZXz0KPHjQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727076AbfKGFry convert rfc822-to-8bit (ORCPT ); Thu, 7 Nov 2019 00:47:54 -0500 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:44610 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725763AbfKGFrx (ORCPT ); Thu, 7 Nov 2019 00:47:53 -0500 Received: from pps.filterd (m0109333.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id xA75j9kx001044 for ; Wed, 6 Nov 2019 21:47:52 -0800 Received: from mail.thefacebook.com (mailout.thefacebook.com [199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2w41ue3fwa-9 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT) for ; Wed, 06 Nov 2019 21:47:52 -0800 Received: from 2401:db00:12:909f:face:0:3:0 (2620:10d:c081:10::13) by mail.thefacebook.com (2620:10d:c081:35::126) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA) id 15.1.1713.5; Wed, 6 Nov 2019 21:47:13 -0800 Received: by devbig007.ftw2.facebook.com (Postfix, from userid 572438) id C79DA760BC0; Wed, 6 Nov 2019 21:47:10 -0800 (PST) Smtp-Origin-Hostprefix: devbig From: Alexei Starovoitov Smtp-Origin-Hostname: devbig007.ftw2.facebook.com To: CC: , , , , Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH v2 bpf-next 13/17] bpf: Compare BTF types of functions arguments with actual types Date: Wed, 6 Nov 2019 21:46:40 -0800 Message-ID: <20191107054644.1285697-14-ast@kernel.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191107054644.1285697-1-ast@kernel.org> References: <20191107054644.1285697-1-ast@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-11-06_09:2019-11-06,2019-11-06 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 lowpriorityscore=0 clxscore=1034 malwarescore=0 mlxlogscore=919 suspectscore=3 adultscore=0 mlxscore=0 bulkscore=0 phishscore=0 priorityscore=1501 impostorscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1911070060 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Make the verifier check that BTF types of function arguments match actual types passed into top-level BPF program and into BPF-to-BPF calls. If types match such BPF programs and sub-programs will have full support of BPF trampoline. If types mismatch the trampoline has to be conservative. It would have to preserve all 5 BPF arguments and assume 64-bit scalars as arguments. Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 3 ++ include/linux/bpf_verifier.h | 2 + kernel/bpf/btf.c | 78 ++++++++++++++++++++++++++++++++++++ kernel/bpf/verifier.c | 21 ++++++++-- 4 files changed, 100 insertions(+), 4 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index c287dfce2a17..ef9c954021e4 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -487,6 +487,7 @@ struct bpf_prog_aux { bool verifier_zext; /* Zero extensions has been inserted by verifier. */ bool offload_requested; bool attach_btf_trace; /* true if attaching to BTF-enabled raw tp */ + bool func_proto_unreliable; enum bpf_tramp_prog_type trampoline_prog_type; struct bpf_trampoline *trampoline; struct hlist_node tramp_hlist; @@ -883,6 +884,8 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, const char *func_name, struct btf_func_model *m); +int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog); + #else /* !CONFIG_BPF_SYSCALL */ static inline struct bpf_prog *bpf_prog_get(u32 ufd) { diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 6e7284ea1468..9d4b2103479d 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -343,9 +343,11 @@ static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log) #define BPF_MAX_SUBPROGS 256 struct bpf_subprog_info { + /* 'start' has to be the first field otherwise find_subprog() won't work */ u32 start; /* insn idx of function entry point */ u32 linfo_idx; /* The idx to the main_prog->aux->linfo */ u16 stack_depth; /* max. stack depth used by this function */ + bool func_proto_unreliable; }; /* single container for all structs diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 7155787a0b13..050ec34bdd73 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3748,6 +3748,84 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, return 0; } +int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog) +{ + struct bpf_verifier_state *st = env->cur_state; + struct bpf_func_state *func = st->frame[st->curframe]; + struct bpf_reg_state *reg = func->regs; + struct bpf_verifier_log *log = &env->log; + struct bpf_prog *prog = env->prog; + struct btf *btf = prog->aux->btf; + const struct btf_param *args; + const struct btf_type *t; + u32 i, nargs, btf_id; + const char *tname; + + if (!prog->aux->func_info) + return 0; + + btf_id = prog->aux->func_info[subprog].type_id; + if (!btf_id) + return 0; + + if (env->subprog_info[subprog].func_proto_unreliable) + return 0; + + t = btf_type_by_id(btf, btf_id); + if (!t || !btf_type_is_func(t)) { + bpf_log(log, "BTF of subprog %d doesn't point to KIND_FUNC\n", + subprog); + return -EINVAL; + } + tname = btf_name_by_offset(btf, t->name_off); + + t = btf_type_by_id(btf, t->type); + if (!t || !btf_type_is_func_proto(t)) { + bpf_log(log, "Invalid type of func %s\n", tname); + return -EINVAL; + } + args = (const struct btf_param *)(t + 1); + nargs = btf_type_vlen(t); + if (nargs > 5) { + bpf_log(log, "Function %s has %d > 5 args\n", tname, nargs); + goto out; + } + /* check that BTF function arguments match actual types that the + * verifier sees. + */ + for (i = 0; i < nargs; i++) { + t = btf_type_by_id(btf, args[i].type); + while (btf_type_is_modifier(t)) + t = btf_type_by_id(btf_vmlinux, t->type); + if (btf_type_is_int(t) || btf_type_is_enum(t)) { + if (reg[i + 1].type == SCALAR_VALUE) + continue; + bpf_log(log, + "R%d is not a scalar\n", + i + 1); + goto out; + } + if (btf_type_is_ptr(t)) { + if (reg[i + 1].type == SCALAR_VALUE) { + bpf_log(log, + "R%d is not a pointer\n", + i + 1); + goto out; + } + continue; + } + bpf_log(log, "Unrecognized argument type %s\n", + btf_kind_str[BTF_INFO_KIND(t->info)]); + goto out; + } + return 0; +out: + bpf_log(log, + "Type info disagrees with actual arguments due to compiler optimizations\n"); + env->subprog_info[subprog].func_proto_unreliable = true; + return 0; +} + void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj, struct seq_file *m) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index c4fd11a27d81..e5ccd9afb1e7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3970,6 +3970,9 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, /* only increment it after check_reg_arg() finished */ state->curframe++; + if (btf_check_func_arg_match(env, subprog)) + return -EINVAL; + /* and go analyze first insn of the callee */ *insn_idx = target_insn; @@ -6646,7 +6649,6 @@ static int check_btf_func(struct bpf_verifier_env *env, ret = -EINVAL; goto err_free; } - prev_offset = krecord[i].insn_off; urecord += urec_size; } @@ -6662,13 +6664,21 @@ static int check_btf_func(struct bpf_verifier_env *env, static void adjust_btf_func(struct bpf_verifier_env *env) { + struct bpf_prog_aux *aux = env->prog->aux; int i; - if (!env->prog->aux->func_info) + if (!aux->func_info) return; - for (i = 0; i < env->subprog_cnt; i++) - env->prog->aux->func_info[i].insn_off = env->subprog_info[i].start; + for (i = 0; i < env->subprog_cnt; i++) { + aux->func_info[i].insn_off = env->subprog_info[i].start; + if (env->subprog_info[i].func_proto_unreliable) { + if (i == 0) + aux->func_proto_unreliable = true; + else + aux->func[i]->aux->func_proto_unreliable = true; + } + } } #define MIN_BPF_LINEINFO_SIZE (offsetof(struct bpf_line_info, line_col) + \ @@ -7649,6 +7659,9 @@ static int do_check(struct bpf_verifier_env *env) 0 /* frameno */, 0 /* subprogno, zero == main subprog */); + if (btf_check_func_arg_match(env, 0)) + return -EINVAL; + for (;;) { struct bpf_insn *insn; u8 class; -- 2.23.0