From patchwork Tue Feb 2 18:56:48 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrea Mayer X-Patchwork-Id: 12062705 X-Patchwork-Delegate: kuba@kernel.org 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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 0E1AEC433E0 for ; Tue, 2 Feb 2021 19:10:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B2D4964E92 for ; Tue, 2 Feb 2021 19:10:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239463AbhBBTKd (ORCPT ); Tue, 2 Feb 2021 14:10:33 -0500 Received: from smtp.uniroma2.it ([160.80.6.16]:60991 "EHLO smtp.uniroma2.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239414AbhBBTIE (ORCPT ); Tue, 2 Feb 2021 14:08:04 -0500 X-Greylist: delayed 537 seconds by postgrey-1.27 at vger.kernel.org; Tue, 02 Feb 2021 14:07:59 EST Received: from localhost.localdomain ([160.80.103.126]) by smtp-2015.uniroma2.it (8.14.4/8.14.4/Debian-8) with ESMTP id 112IvMQa000423 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Tue, 2 Feb 2021 19:57:23 +0100 From: Andrea Mayer To: "David S. Miller" , Hideaki YOSHIFUJI , David Ahern , Jakub Kicinski , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Cc: Colin Ian King , Stefano Salsano , Paolo Lungaroni , Ahmed Abdelsalam , Andrea Mayer Subject: [PATCH net-next] seg6: fool-proof the processing of SRv6 behavior attributes Date: Tue, 2 Feb 2021 19:56:48 +0100 Message-Id: <20210202185648.11654-1-andrea.mayer@uniroma2.it> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-Virus-Scanned: clamav-milter 0.100.0 at smtp-2015 X-Virus-Status: Clean Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org The set of required attributes for a given SRv6 behavior is identified using a bitmap stored in an unsigned long, since the initial design of SRv6 networking in Linux. Recently the same approach has been used for identifying the optional attributes. However, the number of attributes supported by SRv6 behaviors depends on the size of the unsigned long type which changes with the architecture. Indeed, on a 64-bit architecture, an SRv6 behavior can support up to 64 attributes while on a 32-bit architecture it can support at most 32 attributes. To fool-proof the processing of SRv6 behaviors we will support at most 32 attributes independently from the reference architecture. Consequently, this patch aims to: - verify, at compile time, that the total number of attributes does not exceed the fixed value of 32. Otherwise, kernel build fails forcing developers to reconsider adding a new attribute or extend the total number of supported attributes by the SRv6 behaviors. - replace all patterns (1 << i) with the macro SEG6_F_ATTR(i) in order to address potential overflow issues caused by 32-bit signed arithmetic. Thanks to Colin Ian King for catching the overflow problem, providing a solution and inspiring this patch. Thanks to Jakub Kicinski for his useful suggestions during the design of this patch. Signed-off-by: Andrea Mayer --- net/ipv6/seg6_local.c | 68 +++++++++++++++++++++++++------------------ 1 file changed, 40 insertions(+), 28 deletions(-) diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c index b07f7c1c82a4..7cc50d506902 100644 --- a/net/ipv6/seg6_local.c +++ b/net/ipv6/seg6_local.c @@ -31,6 +31,9 @@ #include #include +#define SEG6_F_ATTR(i) BIT(i) +#define SEG6_LOCAL_MAX_SUPP 32 + struct seg6_local_lwt; /* callbacks used for customizing the creation and destruction of a behavior */ @@ -660,8 +663,8 @@ seg6_end_dt_mode seg6_end_dt6_parse_mode(struct seg6_local_lwt *slwt) unsigned long parsed_optattrs = slwt->parsed_optattrs; bool legacy, vrfmode; - legacy = !!(parsed_optattrs & (1 << SEG6_LOCAL_TABLE)); - vrfmode = !!(parsed_optattrs & (1 << SEG6_LOCAL_VRFTABLE)); + legacy = !!(parsed_optattrs & SEG6_F_ATTR(SEG6_LOCAL_TABLE)); + vrfmode = !!(parsed_optattrs & SEG6_F_ATTR(SEG6_LOCAL_VRFTABLE)); if (!(legacy ^ vrfmode)) /* both are absent or present: invalid DT6 mode */ @@ -883,32 +886,32 @@ static struct seg6_action_desc seg6_action_table[] = { }, { .action = SEG6_LOCAL_ACTION_END_X, - .attrs = (1 << SEG6_LOCAL_NH6), + .attrs = SEG6_F_ATTR(SEG6_LOCAL_NH6), .input = input_action_end_x, }, { .action = SEG6_LOCAL_ACTION_END_T, - .attrs = (1 << SEG6_LOCAL_TABLE), + .attrs = SEG6_F_ATTR(SEG6_LOCAL_TABLE), .input = input_action_end_t, }, { .action = SEG6_LOCAL_ACTION_END_DX2, - .attrs = (1 << SEG6_LOCAL_OIF), + .attrs = SEG6_F_ATTR(SEG6_LOCAL_OIF), .input = input_action_end_dx2, }, { .action = SEG6_LOCAL_ACTION_END_DX6, - .attrs = (1 << SEG6_LOCAL_NH6), + .attrs = SEG6_F_ATTR(SEG6_LOCAL_NH6), .input = input_action_end_dx6, }, { .action = SEG6_LOCAL_ACTION_END_DX4, - .attrs = (1 << SEG6_LOCAL_NH4), + .attrs = SEG6_F_ATTR(SEG6_LOCAL_NH4), .input = input_action_end_dx4, }, { .action = SEG6_LOCAL_ACTION_END_DT4, - .attrs = (1 << SEG6_LOCAL_VRFTABLE), + .attrs = SEG6_F_ATTR(SEG6_LOCAL_VRFTABLE), #ifdef CONFIG_NET_L3_MASTER_DEV .input = input_action_end_dt4, .slwt_ops = { @@ -920,30 +923,30 @@ static struct seg6_action_desc seg6_action_table[] = { .action = SEG6_LOCAL_ACTION_END_DT6, #ifdef CONFIG_NET_L3_MASTER_DEV .attrs = 0, - .optattrs = (1 << SEG6_LOCAL_TABLE) | - (1 << SEG6_LOCAL_VRFTABLE), + .optattrs = SEG6_F_ATTR(SEG6_LOCAL_TABLE) | + SEG6_F_ATTR(SEG6_LOCAL_VRFTABLE), .slwt_ops = { .build_state = seg6_end_dt6_build, }, #else - .attrs = (1 << SEG6_LOCAL_TABLE), + .attrs = SEG6_F_ATTR(SEG6_LOCAL_TABLE), #endif .input = input_action_end_dt6, }, { .action = SEG6_LOCAL_ACTION_END_B6, - .attrs = (1 << SEG6_LOCAL_SRH), + .attrs = SEG6_F_ATTR(SEG6_LOCAL_SRH), .input = input_action_end_b6, }, { .action = SEG6_LOCAL_ACTION_END_B6_ENCAP, - .attrs = (1 << SEG6_LOCAL_SRH), + .attrs = SEG6_F_ATTR(SEG6_LOCAL_SRH), .input = input_action_end_b6_encap, .static_headroom = sizeof(struct ipv6hdr), }, { .action = SEG6_LOCAL_ACTION_END_BPF, - .attrs = (1 << SEG6_LOCAL_BPF), + .attrs = SEG6_F_ATTR(SEG6_LOCAL_BPF), .input = input_action_end_bpf, }, @@ -1366,7 +1369,7 @@ static void __destroy_attrs(unsigned long parsed_attrs, int max_parsed, * attribute; otherwise, we call the destroy() callback. */ for (i = 0; i < max_parsed; ++i) { - if (!(parsed_attrs & (1 << i))) + if (!(parsed_attrs & SEG6_F_ATTR(i))) continue; param = &seg6_action_params[i]; @@ -1395,7 +1398,7 @@ static int parse_nla_optional_attrs(struct nlattr **attrs, int err, i; for (i = 0; i < SEG6_LOCAL_MAX + 1; ++i) { - if (!(desc->optattrs & (1 << i)) || !attrs[i]) + if (!(desc->optattrs & SEG6_F_ATTR(i)) || !attrs[i]) continue; /* once here, the i-th attribute is provided by the @@ -1408,7 +1411,7 @@ static int parse_nla_optional_attrs(struct nlattr **attrs, goto parse_optattrs_err; /* current attribute has been correctly parsed */ - parsed_optattrs |= (1 << i); + parsed_optattrs |= SEG6_F_ATTR(i); } /* store in the tunnel state all the optional attributed successfully @@ -1494,7 +1497,7 @@ static int parse_nla_action(struct nlattr **attrs, struct seg6_local_lwt *slwt) /* parse the required attributes */ for (i = 0; i < SEG6_LOCAL_MAX + 1; i++) { - if (desc->attrs & (1 << i)) { + if (desc->attrs & SEG6_F_ATTR(i)) { if (!attrs[i]) return -EINVAL; @@ -1599,7 +1602,7 @@ static int seg6_local_fill_encap(struct sk_buff *skb, attrs = slwt->desc->attrs | slwt->parsed_optattrs; for (i = 0; i < SEG6_LOCAL_MAX + 1; i++) { - if (attrs & (1 << i)) { + if (attrs & SEG6_F_ATTR(i)) { param = &seg6_action_params[i]; err = param->put(skb, slwt); if (err < 0) @@ -1620,30 +1623,30 @@ static int seg6_local_get_encap_size(struct lwtunnel_state *lwt) attrs = slwt->desc->attrs | slwt->parsed_optattrs; - if (attrs & (1 << SEG6_LOCAL_SRH)) + if (attrs & SEG6_F_ATTR(SEG6_LOCAL_SRH)) nlsize += nla_total_size((slwt->srh->hdrlen + 1) << 3); - if (attrs & (1 << SEG6_LOCAL_TABLE)) + if (attrs & SEG6_F_ATTR(SEG6_LOCAL_TABLE)) nlsize += nla_total_size(4); - if (attrs & (1 << SEG6_LOCAL_NH4)) + if (attrs & SEG6_F_ATTR(SEG6_LOCAL_NH4)) nlsize += nla_total_size(4); - if (attrs & (1 << SEG6_LOCAL_NH6)) + if (attrs & SEG6_F_ATTR(SEG6_LOCAL_NH6)) nlsize += nla_total_size(16); - if (attrs & (1 << SEG6_LOCAL_IIF)) + if (attrs & SEG6_F_ATTR(SEG6_LOCAL_IIF)) nlsize += nla_total_size(4); - if (attrs & (1 << SEG6_LOCAL_OIF)) + if (attrs & SEG6_F_ATTR(SEG6_LOCAL_OIF)) nlsize += nla_total_size(4); - if (attrs & (1 << SEG6_LOCAL_BPF)) + if (attrs & SEG6_F_ATTR(SEG6_LOCAL_BPF)) nlsize += nla_total_size(sizeof(struct nlattr)) + nla_total_size(MAX_PROG_NAME) + nla_total_size(4); - if (attrs & (1 << SEG6_LOCAL_VRFTABLE)) + if (attrs & SEG6_F_ATTR(SEG6_LOCAL_VRFTABLE)) nlsize += nla_total_size(4); return nlsize; @@ -1670,7 +1673,7 @@ static int seg6_local_cmp_encap(struct lwtunnel_state *a, return 1; for (i = 0; i < SEG6_LOCAL_MAX + 1; i++) { - if (attrs_a & (1 << i)) { + if (attrs_a & SEG6_F_ATTR(i)) { param = &seg6_action_params[i]; if (param->cmp(slwt_a, slwt_b)) return 1; @@ -1692,6 +1695,15 @@ static const struct lwtunnel_encap_ops seg6_local_ops = { int __init seg6_local_init(void) { + /* If the max total number of defined attributes is reached, then your + * kernel build stops here. + * + * This check is required to avoid arithmetic overflows when processing + * behavior attributes and the maximum number of defined attributes + * exceeds the allowed value. + */ + BUILD_BUG_ON(SEG6_LOCAL_MAX + 1 > SEG6_LOCAL_MAX_SUPP); + return lwtunnel_encap_add_ops(&seg6_local_ops, LWTUNNEL_ENCAP_SEG6_LOCAL); }