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=-11.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 52B93C433DF for ; Tue, 25 Aug 2020 19:23:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 36DDE2071E for ; Tue, 25 Aug 2020 19:23:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598383400; bh=DZgxDW+XQJ7FtxDWtY9WT+byFRhCVK8m1ISa71Id3D0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=TGVoX82Lz/FWf9Ok/0t/3uaYMN4TyY2iwXAtrXHSuPQT0meCk1jNybLk2kDVQ8fJf cZ369VMTLpy9ghoQ0KjVhaYEmZR7ES45hjKOrHQmd6k6nFM2/Qkqa9K2YCi4ft7pNF ons4XMWFBVk570VvqZ+kZkr+z1E+fI2Lb2SozRG8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726999AbgHYTXT convert rfc822-to-8bit (ORCPT ); Tue, 25 Aug 2020 15:23:19 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:34954 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726090AbgHYTXS (ORCPT ); Tue, 25 Aug 2020 15:23:18 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-291-L73Sk5FaPius9RJG_ddvOA-1; Tue, 25 Aug 2020 15:22:07 -0400 X-MC-Unique: L73Sk5FaPius9RJG_ddvOA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 869BD801AAD; Tue, 25 Aug 2020 19:22:05 +0000 (UTC) Received: from krava.redhat.com (unknown [10.40.192.4]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6731819C4F; Tue, 25 Aug 2020 19:22:02 +0000 (UTC) From: Jiri Olsa To: Alexei Starovoitov , Daniel Borkmann Cc: Andrii Nakryiko , netdev@vger.kernel.org, bpf@vger.kernel.org, Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Jesper Dangaard Brouer Subject: [PATCH v12 bpf-next 08/14] bpf: Add btf_struct_ids_match function Date: Tue, 25 Aug 2020 21:21:18 +0200 Message-Id: <20200825192124.710397-9-jolsa@kernel.org> In-Reply-To: <20200825192124.710397-1-jolsa@kernel.org> References: <20200825192124.710397-1-jolsa@kernel.org> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jolsa@kernel.org X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: kernel.org Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Adding btf_struct_ids_match function to check if given address provided by BTF object + offset is also address of another nested BTF object. This allows to pass an argument to helper, which is defined via parent BTF object + offset, like for bpf_d_path (added in following changes): SEC("fentry/filp_close") int BPF_PROG(prog_close, struct file *file, void *id) { ... ret = bpf_d_path(&file->f_path, ... The first bpf_d_path argument is hold by verifier as BTF file object plus offset of f_path member. The btf_struct_ids_match function will walk the struct file object and check if there's nested struct path object on the given offset. Acked-by: Andrii Nakryiko Signed-off-by: Jiri Olsa --- include/linux/bpf.h | 2 ++ kernel/bpf/btf.c | 31 +++++++++++++++++++++++++++++++ kernel/bpf/verifier.c | 17 +++++++++++------ 3 files changed, 44 insertions(+), 6 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 81f38e2fda78..d6c356abcc0f 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1350,6 +1350,8 @@ int btf_struct_access(struct bpf_verifier_log *log, const struct btf_type *t, int off, int size, enum bpf_access_type atype, u32 *next_btf_id); +bool btf_struct_ids_match(struct bpf_verifier_log *log, + int off, u32 id, u32 need_type_id); int btf_resolve_helper_id(struct bpf_verifier_log *log, const struct bpf_func_proto *fn, int); diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index d8d64201c4e0..df966acaaeb1 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -4160,6 +4160,37 @@ int btf_struct_access(struct bpf_verifier_log *log, return -EINVAL; } +bool btf_struct_ids_match(struct bpf_verifier_log *log, + int off, u32 id, u32 need_type_id) +{ + const struct btf_type *type; + int err; + + /* Are we already done? */ + if (need_type_id == id && off == 0) + return true; + +again: + type = btf_type_by_id(btf_vmlinux, id); + if (!type) + return false; + err = btf_struct_walk(log, type, off, 1, &id); + if (err != WALK_STRUCT) + return false; + + /* We found nested struct object. If it matches + * the requested ID, we're done. Otherwise let's + * continue the search with offset 0 in the new + * type. + */ + if (need_type_id != id) { + off = 0; + goto again; + } + + return true; +} + int btf_resolve_helper_id(struct bpf_verifier_log *log, const struct bpf_func_proto *fn, int arg) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index dd24503ab3d3..0689d6e66245 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3995,16 +3995,21 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, goto err_type; } } else if (arg_type == ARG_PTR_TO_BTF_ID) { + bool ids_match = false; + expected_type = PTR_TO_BTF_ID; if (type != expected_type) goto err_type; if (!fn->check_btf_id) { if (reg->btf_id != meta->btf_id) { - verbose(env, "Helper has type %s got %s in R%d\n", - kernel_type_name(meta->btf_id), - kernel_type_name(reg->btf_id), regno); - - return -EACCES; + ids_match = btf_struct_ids_match(&env->log, reg->off, reg->btf_id, + meta->btf_id); + if (!ids_match) { + verbose(env, "Helper has type %s got %s in R%d\n", + kernel_type_name(meta->btf_id), + kernel_type_name(reg->btf_id), regno); + return -EACCES; + } } } else if (!fn->check_btf_id(reg->btf_id, arg)) { verbose(env, "Helper does not support %s in R%d\n", @@ -4012,7 +4017,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, return -EACCES; } - if (!tnum_is_const(reg->var_off) || reg->var_off.value || reg->off) { + if ((reg->off && !ids_match) || !tnum_is_const(reg->var_off) || reg->var_off.value) { verbose(env, "R%d is a pointer to in-kernel struct with non-zero offset\n", regno); return -EACCES; -- 2.25.4