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=-7.1 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 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 15E58C28CBC for ; Wed, 6 May 2020 13:30:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E1CEC20746 for ; Wed, 6 May 2020 13:30:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588771823; bh=YHbvr3p/o1/mn+w850/xtJBXXRxPdaMP/LhSjXjNM9A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=PEUUjuu6vupukCfVsPNFrSBmRbRZq02TMU28Nf6Bh4H+AhNrkE9TvuJjz0sLacvy0 nZ9AWtq0VYH/rUTPy8Ay9x5W9BuhAKrq1+Z2rp8YzgWfSDReiPSKzVmsxQM23fRXSf 6s+QaUk8Ips6PBRdL/keS6XfbteTJCQ2wbDJ0uiY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728483AbgEFNaX convert rfc822-to-8bit (ORCPT ); Wed, 6 May 2020 09:30:23 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:51953 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728667AbgEFNaW (ORCPT ); Wed, 6 May 2020 09:30:22 -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-417-UvnxjWGxN3Wur39OBX0BsQ-1; Wed, 06 May 2020 09:30:16 -0400 X-MC-Unique: UvnxjWGxN3Wur39OBX0BsQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2E4CD1902EB7; Wed, 6 May 2020 13:30:14 +0000 (UTC) Received: from krava.redhat.com (unknown [10.40.192.32]) by smtp.corp.redhat.com (Postfix) with ESMTP id B7A40605F7; Wed, 6 May 2020 13:30:09 +0000 (UTC) From: Jiri Olsa To: Alexei Starovoitov , Daniel Borkmann Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, Yonghong Song , Martin KaFai Lau , David Miller , John Fastabend , Jesper Dangaard Brouer , Wenbo Zhang , KP Singh , Andrii Nakryiko , bgregg@netflix.com, Florent Revest , Al Viro Subject: [PATCH 5/9] bpf: Add support to check on BTF id whitelist for d_path helper Date: Wed, 6 May 2020 15:29:42 +0200 Message-Id: <20200506132946.2164578-6-jolsa@kernel.org> In-Reply-To: <20200506132946.2164578-1-jolsa@kernel.org> References: <20200506132946.2164578-1-jolsa@kernel.org> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: kernel.org Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org The BPF helper whitelist checking works as follows: - helper's whitelist is defined as list of functions in file: kernel/bpf/helpers-whitelist/helper - at vmlinux linking time, the bpfwl tool reads the whitelist and translates functions into BTF IDs, which are compiled as following data section into vmlinux object: .BTF_whitelist BTF_whitelist_ BTF_whitelist_ BTF_whitelist_ Each BTF_whitelist_ data is a sorted array of BTF ids. - new 'allowed' function is added to 'struct bpf_func_proto', which is used by verifier code to check (if defined) on whether the helper is called from allowed function (from whitelist). Currently it's needed and implemented only for d_path helper, but it's easy to add for another helper. Signed-off-by: Jiri Olsa --- include/asm-generic/vmlinux.lds.h | 5 +++++ include/linux/bpf.h | 1 + kernel/bpf/verifier.c | 5 +++++ kernel/trace/bpf_trace.c | 23 +++++++++++++++++++++++ 4 files changed, 34 insertions(+) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 71e387a5fe90..6f7ca4f36ed7 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -631,6 +631,11 @@ __start_BTF = .; \ *(.BTF) \ __stop_BTF = .; \ + } \ + .BTF_whitelist : AT(ADDR(.BTF_whitelist) - LOAD_OFFSET) { \ + __start_BTF_whitelist_d_path = .; \ + *(.BTF_whitelist_d_path) \ + __stop_BTF_whitelist_d_path = .; \ } #else #define BTF diff --git a/include/linux/bpf.h b/include/linux/bpf.h index bc589cdd8c34..ccacf488429f 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -275,6 +275,7 @@ struct bpf_func_proto { enum bpf_arg_type arg_type[5]; }; int *btf_id; /* BTF ids of arguments */ + bool (*allowed)(const struct bpf_prog *prog); }; /* bpf_context is intentionally undefined structure. Pointer to bpf_context is diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index b988df5ada20..55995de954a0 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4525,6 +4525,11 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn return -EINVAL; } + if (fn->allowed && !fn->allowed(env->prog)) { + verbose(env, "helper call is not allowed in probe\n"); + return -EINVAL; + } + /* With LD_ABS/IND some JITs save/restore skb from r1. */ changes_data = bpf_helper_changes_pkt_data(fn->func); if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) { diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 3097ab04bdc4..55682d610534 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -13,6 +13,7 @@ #include #include #include +#include #include @@ -797,6 +798,27 @@ BPF_CALL_3(bpf_d_path, struct path *, path, char *, buf, u32, sz) return len; } +extern char __weak __start_BTF_whitelist_d_path[]; +extern char __weak __stop_BTF_whitelist_d_path[]; + +static int btf_id_cmp_func(const void *a, const void *b) +{ + const unsigned long *pa = a; + const unsigned long *pb = b; + + return *pa - *pb; +} + +static bool bpf_d_path_allowed(const struct bpf_prog *prog) +{ + unsigned long *start = (unsigned long *) __start_BTF_whitelist_d_path; + unsigned long *stop = (unsigned long *) __stop_BTF_whitelist_d_path; + unsigned long id = prog->aux->attach_btf_id; + + return bsearch(&id, start, stop - start, sizeof(unsigned long), + btf_id_cmp_func) != NULL; +} + static u32 bpf_d_path_btf_ids[3]; static const struct bpf_func_proto bpf_d_path_proto = { .func = bpf_d_path, @@ -806,6 +828,7 @@ static const struct bpf_func_proto bpf_d_path_proto = { .arg2_type = ARG_PTR_TO_MEM, .arg3_type = ARG_CONST_SIZE, .btf_id = bpf_d_path_btf_ids, + .allowed = bpf_d_path_allowed, }; const struct bpf_func_proto * -- 2.25.4