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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DFFC6C4707A for ; Tue, 12 Apr 2022 07:45:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358357AbiDLHl1 (ORCPT ); Tue, 12 Apr 2022 03:41:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45722 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353349AbiDLHPO (ORCPT ); Tue, 12 Apr 2022 03:15:14 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F1FF393C9; Mon, 11 Apr 2022 23:56:53 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5A23B6158E; Tue, 12 Apr 2022 06:56:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6CBE6C385A1; Tue, 12 Apr 2022 06:56:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649746612; bh=en1lduSAZMJqlcpjsWnyj4N6Vi7Ju+gSq8fZkkkk1Wo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mvA+ndCvM/aY7FMCT83LDaPsm6diEgtmdvOUUrLfyCKpnRc/fBcCorZc3He3A8UBN rrTALsAGrI9H0hCRkgQp30t5nN2ocELK7TQFqsLmJu24S2FhHfrC5DFepaQ+R3QV7H aeD5VjmkYU+gl/Me4fL9LT1iTA1eSugYx53ZNDDg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Menglong Dong , Jakub Sitnicki , Alexei Starovoitov , Sasha Levin Subject: [PATCH 5.16 031/285] bpf: Make dst_port field in struct bpf_sock 16-bit wide Date: Tue, 12 Apr 2022 08:28:08 +0200 Message-Id: <20220412062944.575866124@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220412062943.670770901@linuxfoundation.org> References: <20220412062943.670770901@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jakub Sitnicki [ Upstream commit 4421a582718ab81608d8486734c18083b822390d ] Menglong Dong reports that the documentation for the dst_port field in struct bpf_sock is inaccurate and confusing. From the BPF program PoV, the field is a zero-padded 16-bit integer in network byte order. The value appears to the BPF user as if laid out in memory as so: offsetof(struct bpf_sock, dst_port) + 0 + 8 +16 0x00 +24 0x00 32-, 16-, and 8-bit wide loads from the field are all allowed, but only if the offset into the field is 0. 32-bit wide loads from dst_port are especially confusing. The loaded value, after converting to host byte order with bpf_ntohl(dst_port), contains the port number in the upper 16-bits. Remove the confusion by splitting the field into two 16-bit fields. For backward compatibility, allow 32-bit wide loads from offsetof(struct bpf_sock, dst_port). While at it, allow loads 8-bit loads at offset [0] and [1] from dst_port. Reported-by: Menglong Dong Signed-off-by: Jakub Sitnicki Link: https://lore.kernel.org/r/20220130115518.213259-2-jakub@cloudflare.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- include/uapi/linux/bpf.h | 3 ++- net/core/filter.c | 10 +++++++++- 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 2b3c3f83076c..61bbaf340a89 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -5414,7 +5414,8 @@ struct bpf_sock { __u32 src_ip4; __u32 src_ip6[4]; __u32 src_port; /* host byte order */ - __u32 dst_port; /* network byte order */ + __be16 dst_port; /* network byte order */ + __u16 :16; /* zero padding */ __u32 dst_ip4; __u32 dst_ip6[4]; __u32 state; diff --git a/net/core/filter.c b/net/core/filter.c index d4cdf11656b3..4721ed65bcc5 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -7975,6 +7975,7 @@ bool bpf_sock_is_valid_access(int off, int size, enum bpf_access_type type, struct bpf_insn_access_aux *info) { const int size_default = sizeof(__u32); + int field_size; if (off < 0 || off >= sizeof(struct bpf_sock)) return false; @@ -7986,7 +7987,6 @@ bool bpf_sock_is_valid_access(int off, int size, enum bpf_access_type type, case offsetof(struct bpf_sock, family): case offsetof(struct bpf_sock, type): case offsetof(struct bpf_sock, protocol): - case offsetof(struct bpf_sock, dst_port): case offsetof(struct bpf_sock, src_port): case offsetof(struct bpf_sock, rx_queue_mapping): case bpf_ctx_range(struct bpf_sock, src_ip4): @@ -7995,6 +7995,14 @@ bool bpf_sock_is_valid_access(int off, int size, enum bpf_access_type type, case bpf_ctx_range_till(struct bpf_sock, dst_ip6[0], dst_ip6[3]): bpf_ctx_record_field_size(info, size_default); return bpf_ctx_narrow_access_ok(off, size, size_default); + case bpf_ctx_range(struct bpf_sock, dst_port): + field_size = size == size_default ? + size_default : sizeof_field(struct bpf_sock, dst_port); + bpf_ctx_record_field_size(info, field_size); + return bpf_ctx_narrow_access_ok(off, size, field_size); + case offsetofend(struct bpf_sock, dst_port) ... + offsetof(struct bpf_sock, dst_ip4) - 1: + return false; } return size == size_default; -- 2.35.1