From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gandalf.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) by passt.top (Postfix) with ESMTPS id 9102A5A0279 for ; Mon, 19 Feb 2024 04:08:30 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=202312; t=1708312108; bh=el88E9F9jL4szS0y3ApNSlfPnCVCczjXVaURLSdVsIs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MoVed9t2ZfZs45CxyP+FaQcUzRhc7YcC26Mn3oT736RUfSbFBXbRKX4i3tvwXmnxx ZoDedgMxEo3NvsNw0fqboiDAgFLGnhor2JE4hSzKBydDoDpnhenKAVIxw9gSIw3pEu 26IgLnHcSaSjDwjhpTyK2QyJTvOKAyKF4Z9i4pmDzYF0DhaSHD81nCs/nmmVwwKCCg vXMvfPrHmyiLNlmyOOe0UMLhcZ8aXeRzS/Qm4b91rNNtoVqxhikW+MOkAKAFXcsg42 G0/EeKc4+WI+4xCS0Z6XojtHVSrylnuuDWMaOkOMuJzQbH1ibJ9q/xCttjR2xtTP6I 4rTxZWUvjkC5Q== Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4TdSCw1zCTz4wcM; Mon, 19 Feb 2024 14:08:28 +1100 (AEDT) Date: Mon, 19 Feb 2024 14:08:23 +1100 From: David Gibson To: Laurent Vivier Subject: Re: [PATCH v3 7/9] checksum: introduce functions to compute the header part checksum for TCP/UDP Message-ID: References: <20240217150725.661467-1-lvivier@redhat.com> <20240217150725.661467-8-lvivier@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="ORPKYRifmDOA6lKO" Content-Disposition: inline In-Reply-To: <20240217150725.661467-8-lvivier@redhat.com> Message-ID-Hash: UAUPRGA37345ASWU5EIJWUR2SVQL4KTB X-Message-ID-Hash: UAUPRGA37345ASWU5EIJWUR2SVQL4KTB X-MailFrom: dgibson@gandalf.ozlabs.org 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: 3.3.8 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: --ORPKYRifmDOA6lKO Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Feb 17, 2024 at 04:07:23PM +0100, Laurent Vivier wrote: > The TCP and UDP checksums are computed using the data in the TCP/UDP > payload but also some informations in the IP header (protocol, > length, source and destination addresses). >=20 > We add two functions, proto_ipv4_header_psum() and > proto_ipv6_header_psum(), to compute the checksum of the IP > header part. >=20 > Signed-off-by: Laurent Vivier > --- >=20 > Notes: > v3: > - function parameters provide tot_len, saddr, daddr and protocol > rather than an iphdr/ipv6hdr > =20 > v2: > - move new function to checksum.c > - use _psum rather than _checksum in the name > - replace csum_udp4() and csum_udp6() by the new function >=20 > checksum.c | 67 ++++++++++++++++++++++++++++++++++++++++++------------ > checksum.h | 4 ++++ > tcp.c | 44 ++++++++++++++++------------------- > udp.c | 10 ++++---- > 4 files changed, 81 insertions(+), 44 deletions(-) >=20 > diff --git a/checksum.c b/checksum.c > index 511b296a9a80..55bf1340a257 100644 > --- a/checksum.c > +++ b/checksum.c > @@ -134,6 +134,30 @@ uint16_t csum_ip4_header(uint16_t tot_len, uint8_t p= rotocol, > return ~csum_fold(sum); > } > =20 > +/** > + * proto_ipv4_header_psum() - Calculates the partial checksum of an > + * IPv4 header for UDP or TCP > + * @tot_len: Payload length > + * @proto: Protocol number > + * @saddr: Source address > + * @daddr: Destination address > + * @proto: proto Protocol number > + * Returns: Partial checksum of the IPv4 header > + */ > +uint32_t proto_ipv4_header_psum(uint16_t tot_len, uint8_t protocol, > + uint32_t saddr, uint32_t daddr) > +{ > + uint32_t psum =3D htons(protocol); > + > + psum +=3D (saddr >> 16) & 0xffff; > + psum +=3D saddr & 0xffff; > + psum +=3D (daddr >> 16) & 0xffff; > + psum +=3D daddr & 0xffff; > + psum +=3D htons(ntohs(tot_len) - 20); > + > + return psum; > +} > + > /** > * csum_udp4() - Calculate and set checksum for a UDP over IPv4 packet > * @udp4hr: UDP header, initialised apart from checksum > @@ -150,14 +174,10 @@ void csum_udp4(struct udphdr *udp4hr, > udp4hr->check =3D 0; > =20 > if (UDP4_REAL_CHECKSUMS) { > - /* UNTESTED: if we did want real UDPv4 checksums, this > - * is roughly what we'd need */ > - uint32_t psum =3D csum_fold(saddr.s_addr) > - + csum_fold(daddr.s_addr) > - + htons(len + sizeof(*udp4hr)) > - + htons(IPPROTO_UDP); > - /* Add in partial checksum for the UDP header alone */ > - psum +=3D sum_16b(udp4hr, sizeof(*udp4hr)); > + uint32_t psum =3D proto_ipv4_header_psum(len, IPPROTO_UDP, > + saddr.s_addr, > + daddr.s_addr); > + psum =3D csum_unfolded(udp4hr, sizeof(struct udphdr), psum); > udp4hr->check =3D csum(payload, len, psum); > } > } > @@ -180,6 +200,26 @@ void csum_icmp4(struct icmphdr *icmp4hr, const void = *payload, size_t len) > icmp4hr->checksum =3D csum(payload, len, psum); > } > =20 > +/** > + * proto_ipv6_header_psum() - Calculates the partial checksum of an > + * IPv6 header for UDP or TCP > + * @payload_len: Payload length > + * @proto: Protocol number > + * @saddr: Source address > + * @daddr: Destination address > + * Returns: Partial checksum of the IPv6 header > + */ > +uint32_t proto_ipv6_header_psum(uint16_t payload_len, uint8_t protocol, > + struct in6_addr saddr, struct in6_addr daddr) Hrm, this is passing 2 16-byte IPv6 addresses by value, which might not be what we want. > +{ > + uint32_t sum =3D htons(protocol) + payload_len; Uh.. doesn't that need to be htons(payload_len + sizeof(struct ipv6hdr)) rather than simply payload_len? > + > + sum +=3D sum_16b(&saddr, sizeof(saddr)); > + sum +=3D sum_16b(&daddr, sizeof(daddr)); > + > + return sum; > +} > + > /** > * csum_udp6() - Calculate and set checksum for a UDP over IPv6 packet > * @udp6hr: UDP header, initialised apart from checksum > @@ -190,14 +230,11 @@ void csum_udp6(struct udphdr *udp6hr, > const struct in6_addr *saddr, const struct in6_addr *daddr, > const void *payload, size_t len) > { > - /* Partial checksum for the pseudo-IPv6 header */ > - uint32_t psum =3D sum_16b(saddr, sizeof(*saddr)) + > - sum_16b(daddr, sizeof(*daddr)) + > - htons(len + sizeof(*udp6hr)) + htons(IPPROTO_UDP); > - > + uint32_t psum =3D proto_ipv6_header_psum(len, IPPROTO_UDP, > + *saddr, *daddr); > udp6hr->check =3D 0; > - /* Add in partial checksum for the UDP header alone */ > - psum +=3D sum_16b(udp6hr, sizeof(*udp6hr)); > + > + psum =3D csum_unfolded(udp6hr, sizeof(struct udphdr), psum); > udp6hr->check =3D csum(payload, len, psum); > } > =20 > diff --git a/checksum.h b/checksum.h > index 92db73612b6e..b2b5b8e8b77e 100644 > --- a/checksum.h > +++ b/checksum.h > @@ -15,10 +15,14 @@ uint16_t csum_fold(uint32_t sum); > uint16_t csum_unaligned(const void *buf, size_t len, uint32_t init); > uint16_t csum_ip4_header(uint16_t tot_len, uint8_t protocol, > uint32_t saddr, uint32_t daddr); > +uint32_t proto_ipv4_header_psum(uint16_t tot_len, uint8_t protocol, > + uint32_t saddr, uint32_t daddr); > void csum_udp4(struct udphdr *udp4hr, > struct in_addr saddr, struct in_addr daddr, > const void *payload, size_t len); > void csum_icmp4(struct icmphdr *ih, const void *payload, size_t len); > +uint32_t proto_ipv6_header_psum(uint16_t payload_len, uint8_t protocol, > + struct in6_addr saddr, struct in6_addr daddr); > void csum_udp6(struct udphdr *udp6hr, > const struct in6_addr *saddr, const struct in6_addr *daddr, > const void *payload, size_t len); > diff --git a/tcp.c b/tcp.c > index 8887656d3ee8..8ee252131504 100644 > --- a/tcp.c > +++ b/tcp.c > @@ -938,39 +938,29 @@ static void tcp_sock_set_bufsize(const struct ctx *= c, int s) > * tcp_update_check_tcp4() - Update TCP checksum from stored one > * @buf: L2 packet buffer with final IPv4 header > */ > -static void tcp_update_check_tcp4(struct tcp4_l2_buf_t *buf) > +static void tcp_update_check_tcp4(struct iphdr *iph) > { > - uint16_t tlen =3D ntohs(buf->iph.tot_len) - 20; > - uint32_t sum =3D htons(IPPROTO_TCP); > + struct tcphdr *th =3D (struct tcphdr *)(iph + 1); > + uint16_t tlen =3D ntohs(iph->tot_len) - 20; > + uint32_t sum =3D proto_ipv4_header_psum(iph->tot_len, IPPROTO_TCP, > + iph->saddr, iph->daddr); > =20 > - sum +=3D (buf->iph.saddr >> 16) & 0xffff; > - sum +=3D buf->iph.saddr & 0xffff; > - sum +=3D (buf->iph.daddr >> 16) & 0xffff; > - sum +=3D buf->iph.daddr & 0xffff; > - sum +=3D htons(ntohs(buf->iph.tot_len) - 20); > - > - buf->th.check =3D 0; > - buf->th.check =3D csum(&buf->th, tlen, sum); > + th->check =3D 0; > + th->check =3D csum(th, tlen, sum); > } > =20 > /** > * tcp_update_check_tcp6() - Calculate TCP checksum for IPv6 > * @buf: L2 packet buffer with final IPv6 header > */ > -static void tcp_update_check_tcp6(struct tcp6_l2_buf_t *buf) > +static void tcp_update_check_tcp6(struct ipv6hdr *ip6h) > { > - int len =3D ntohs(buf->ip6h.payload_len) + sizeof(struct ipv6hdr); > - > - buf->ip6h.hop_limit =3D IPPROTO_TCP; > - buf->ip6h.version =3D 0; > - buf->ip6h.nexthdr =3D 0; > + struct tcphdr *th =3D (struct tcphdr *)(ip6h + 1); > + uint32_t sum =3D proto_ipv6_header_psum(ip6h->payload_len, IPPROTO_TCP, > + ip6h->saddr, ip6h->daddr); > =20 > - buf->th.check =3D 0; > - buf->th.check =3D csum(&buf->ip6h, len, 0); > - > - buf->ip6h.hop_limit =3D 255; > - buf->ip6h.version =3D 6; > - buf->ip6h.nexthdr =3D IPPROTO_TCP; > + th->check =3D 0; > + th->check =3D csum(th, ntohs(ip6h->payload_len), sum); > } > =20 > /** > @@ -1382,7 +1372,7 @@ do { \ > =20 > SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq); > =20 > - tcp_update_check_tcp4(b); > + tcp_update_check_tcp4(&b->iph); > =20 > tlen =3D tap_iov_len(c, &b->taph, ip_len); > } else { > @@ -1401,7 +1391,11 @@ do { \ > =20 > SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq); > =20 > - tcp_update_check_tcp6(b); > + tcp_update_check_tcp6(&b->ip6h); > + > + b->ip6h.hop_limit =3D 255; > + b->ip6h.version =3D 6; > + b->ip6h.nexthdr =3D IPPROTO_TCP; > =20 > b->ip6h.flow_lbl[0] =3D (conn->sock >> 16) & 0xf; > b->ip6h.flow_lbl[1] =3D (conn->sock >> 8) & 0xff; > diff --git a/udp.c b/udp.c > index cd34f659210b..e123b35a955c 100644 > --- a/udp.c > +++ b/udp.c > @@ -670,10 +670,12 @@ static size_t udp_update_hdr6(const struct ctx *c, = int n, in_port_t dstport, > b->uh.source =3D b->s_in6.sin6_port; > b->uh.dest =3D htons(dstport); > b->uh.len =3D b->ip6h.payload_len; > - > - b->ip6h.hop_limit =3D IPPROTO_UDP; > - b->ip6h.version =3D b->ip6h.nexthdr =3D b->uh.check =3D 0; > - b->uh.check =3D csum(&b->ip6h, ip_len, 0); > + b->uh.check =3D 0; > + b->uh.check =3D csum(&b->uh, ntohs(b->ip6h.payload_len), > + proto_ipv6_header_psum(b->ip6h.payload_len, > + IPPROTO_UDP, > + b->ip6h.saddr, > + b->ip6h.daddr)); > b->ip6h.version =3D 6; > b->ip6h.nexthdr =3D IPPROTO_UDP; > b->ip6h.hop_limit =3D 255; --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. 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