From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by passt.top (Postfix) with ESMTP id 4F3985A0271 for ; Tue, 18 Oct 2022 10:40:08 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1666082407; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Hn4LPeNSpC/OqNvPYSuoNYl7m8to9yJXCnSuioyr3GU=; b=HJ+ysN7Wrlrfg7SHnP17KeSLK7HSHH9VeybTkZdIge4zVG36IJYGCTril7aOXaja95Iw27 h3g33K2BRQHRgwW8gaTqLqx1+xcee6OGjKKtF8N0VKypO8vhJjO1/KX66LGvC+xIS57t8B uBJOTz7X/blrnSBeKVB/KxLwnN9urg8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-122-hGUwPylRORSKnSjCEMjlqA-1; Tue, 18 Oct 2022 04:40:05 -0400 X-MC-Unique: hGUwPylRORSKnSjCEMjlqA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 5B3C180602A; Tue, 18 Oct 2022 08:40:05 +0000 (UTC) Received: from maya.cloud.tilaa.com (ovpn-208-31.brq.redhat.com [10.40.208.31]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EAF61111DCE6; Tue, 18 Oct 2022 08:40:04 +0000 (UTC) Date: Tue, 18 Oct 2022 05:01:01 +0200 From: Stefano Brivio To: David Gibson Subject: Re: [PATCH 01/14] Add csum_icmp6() helper for calculating ICMPv6 checksums Message-ID: <20221018050101.2b437d40@elisabeth> In-Reply-To: <20221017085807.473470-2-david@gibson.dropbear.id.au> References: <20221017085807.473470-1-david@gibson.dropbear.id.au> <20221017085807.473470-2-david@gibson.dropbear.id.au> Organization: Red Hat MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-ID-Hash: MJWBCKVXJ2ZTNDLQJNAQCF4G7QKO365V X-Message-ID-Hash: MJWBCKVXJ2ZTNDLQJNAQCF4G7QKO365V X-MailFrom: sbrivio@redhat.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: passt-dev@passt.top X-Mailman-Version: 3.3.3 Precedence: list List-Id: Development discussion and patches for passt Archived-At: <> Archived-At: List-Archive: <> List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Mon, 17 Oct 2022 19:57:54 +1100 David Gibson wrote: > At least two places in passt calculate ICMPv6 checksums, ndp() and > tap_ip_send(). Add a helper to handle this calculation in both places. > For future flexibility, the new helper takes parameters for the fields in > the IPv6 pseudo-header, so an IPv6 header or pseudo-header doesn't need to > be explicitly constructed. It also allows the ICMPv6 header and payload to > be in separate buffers, although we don't use this yet. > > Signed-off-by: David Gibson > --- > checksum.c | 27 +++++++++++++++++++++++++++ > checksum.h | 7 +++++++ > ndp.c | 5 +---- > tap.c | 6 ++---- > 4 files changed, 37 insertions(+), 8 deletions(-) > > diff --git a/checksum.c b/checksum.c > index 56ad01e..0e207c8 100644 > --- a/checksum.c > +++ b/checksum.c > @@ -52,6 +52,8 @@ > #include > #include > > +#include > + > /** > * sum_16b() - Calculate sum of 16-bit words > * @buf: Input buffer > @@ -105,6 +107,31 @@ uint16_t csum_unaligned(const void *buf, size_t len, uint32_t init) > return (uint16_t)~csum_fold(sum_16b(buf, len) + init); > } > > +/** > + * csum_icmp6() - Calculate checksum for an ICMPv6 packet "Calculate and set" ...? > + * @icmp6hr: ICMPv6 header, initialized apart from checksum > + * @saddr: IPv6 source address > + * @daddr: IPv6 destination address > + * @payload: ICMP packet payload > + * @len: Length of @payload (not including ICMPv6 header) > + */ > +void csum_icmp6(struct icmp6hdr *icmp6hr, > + const struct in6_addr *saddr, > + const struct in6_addr *daddr, I think: const struct in6_addr *saddr, const struct in6_addr *daddr, would be easier on eyes. > + const void *payload, > + size_t len) > +{ > + /* Partial checksum for the pseudo-IPv6 header */ > + uint32_t psum = sum_16b(saddr, sizeof(*saddr)) + > + sum_16b(daddr, sizeof(*daddr)) + > + htons(len + sizeof(*icmp6hr)) + htons(IPPROTO_ICMPV6); Maybe: uint32_t psum = sum_16b(saddr, sizeof(*saddr)) + sum_16b(daddr, sizeof(*daddr)) + htons(len + sizeof(*icmp6hr)) + htons(IPPROTO_ICMPV6); for me, it turns things from "sum a bunch of things" to "addresses and something else". > + > + icmp6hr->icmp6_cksum = 0; > + /* Add in partial checksum for the ICMPv6 header alone */ > + psum += sum_16b(icmp6hr, sizeof(*icmp6hr)); > + icmp6hr->icmp6_cksum = csum_unaligned(payload, len, psum); > +} > + > /** > * csum_tcp4() - Calculate TCP checksum for IPv4 and set in place > * @iph: Packet buffer, IP header > diff --git a/checksum.h b/checksum.h > index 5418406..2c72200 100644 > --- a/checksum.h > +++ b/checksum.h > @@ -6,9 +6,16 @@ > #ifndef CHECKSUM_H > #define CHECKSUM_H > > +struct icmp6hdr; > + > uint32_t sum_16b(const void *buf, size_t len); > uint16_t csum_fold(uint32_t sum); > uint16_t csum_unaligned(const void *buf, size_t len, uint32_t init); > +void csum_icmp6(struct icmp6hdr *ih, > + const struct in6_addr *saddr, > + const struct in6_addr *daddr, > + const void *payload, > + size_t len); It looks a bit like Haskell. ;) I would really use the horizontal space we have. > void csum_tcp4(struct iphdr *iph); > uint16_t csum(const void *buf, size_t len, uint32_t init); > > diff --git a/ndp.c b/ndp.c > index dec36a9..03f1d06 100644 > --- a/ndp.c > +++ b/ndp.c > @@ -189,10 +189,7 @@ dns_done: > ip6hr->saddr = c->ip6.addr_ll; > > ip6hr->payload_len = htons(sizeof(*ihr) + len); > - ip6hr->hop_limit = IPPROTO_ICMPV6; > - ihr->icmp6_cksum = 0; > - ihr->icmp6_cksum = csum_unaligned(ip6hr, sizeof(*ip6hr) + > - sizeof(*ihr) + len, 0); > + csum_icmp6(ihr, &ip6hr->saddr, &ip6hr->daddr, ihr + 1, len); Nice to see this all going away! > ip6hr->version = 6; > ip6hr->nexthdr = IPPROTO_ICMPV6; > diff --git a/tap.c b/tap.c > index 8b6d9bc..aafc92b 100644 > --- a/tap.c > +++ b/tap.c > @@ -191,10 +191,8 @@ void tap_ip_send(const struct ctx *c, const struct in6_addr *src, uint8_t proto, > } else if (proto == IPPROTO_ICMPV6) { > struct icmp6hdr *ih = (struct icmp6hdr *)(ip6h + 1); > > - ih->icmp6_cksum = 0; > - ih->icmp6_cksum = csum_unaligned(ip6h, > - len + sizeof(*ip6h), > - 0); > + csum_icmp6(ih, &ip6h->saddr, &ip6h->daddr, > + ih + 1, len - sizeof(*ih)); > } > ip6h->version = 6; > ip6h->nexthdr = proto; -- Stefano