From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: passt.top; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: passt.top; dkim=pass (2048-bit key; secure) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.a=rsa-sha256 header.s=202508 header.b=lAZlxgnT; dkim-atps=neutral Received: from mail.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) by passt.top (Postfix) with ESMTPS id 6BE395A027A for ; Thu, 21 Aug 2025 04:03:56 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=202508; t=1755741833; bh=VL3KZOcPngv/8kSmuzhqcQsGbWQhwZBWJktcKIjqwZo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=lAZlxgnT8VLzsAqCxj3WOJlyipzJR5zQ481/on6OsGJMyUSKaJXhAFKNY9LBdq9Hl GGBshvBAvvjW5Iyl8C62lpYoFW9Y4GjucE/iFn3OoXolxEmQUVsSG4J0Ky3eb0taOX 93n2u6MtBZyY2DKG8C5BvygJmi8SH9OMGi0OtqczkajLFqL9hXdSmU9pHI6NiWuTs/ JGkB8yRb98kdt+ewDPhBuEr4oeYv6GlQ37zBnT/Mu10oHtB96mQY0Fn8CCYGFqVrlM u7btm8oDc2pTsBViJM48abCuXKCXVCp4oxlI3kM+4jq/fO0wVS2wv8BhWjDmzTEcmW kWCwpkbBPBwIQ== Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4c6mp11syhz4wbR; Thu, 21 Aug 2025 12:03:53 +1000 (AEST) Date: Thu, 21 Aug 2025 11:32:37 +1000 From: David Gibson To: Jon Maloy Subject: Re: [PATCH v4 4/9] udp: forward external source MAC address through tap interface Message-ID: References: <20250820031005.2725591-1-jmaloy@redhat.com> <20250820031005.2725591-5-jmaloy@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="RNSSiAN+7ympUiEg" Content-Disposition: inline In-Reply-To: <20250820031005.2725591-5-jmaloy@redhat.com> Message-ID-Hash: N3USNWU5MVR6CBCTQBO3VMLTRYD2E7VO X-Message-ID-Hash: N3USNWU5MVR6CBCTQBO3VMLTRYD2E7VO 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: sbrivio@redhat.com, dgibson@redhat.com, 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: --RNSSiAN+7ympUiEg Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Aug 19, 2025 at 11:10:00PM -0400, Jon Maloy wrote: > We forward the incoming MAC address through the tap interface when > receiving incoming packets from network local hosts. Packets from > the own host are excepted from this rule, and are still forwarded > with the default PASST/PASTA MAC address as source. >=20 > This is a part of the solution to bug > https://bugs.passt.top/show_bug.cgi?id=3D120 >=20 > Signed-off-by: Jon Maloy Reviewed-by: David Gibson Excepting nits below. > --- > passt.c | 2 +- > udp.c | 39 ++++++++++++++++++++------------------- > udp.h | 2 +- > 3 files changed, 22 insertions(+), 21 deletions(-) >=20 > diff --git a/passt.c b/passt.c > index 388d10f..477a01f 100644 > --- a/passt.c > +++ b/passt.c > @@ -154,7 +154,7 @@ static void timer_init(struct ctx *c, const struct ti= mespec *now) > void proto_update_l2_buf(const unsigned char *eth_d, const unsigned char= *eth_s) > { > tcp_update_l2_buf(eth_d, eth_s); > - udp_update_l2_buf(eth_d, eth_s); > + udp_update_l2_buf(eth_d); > } > =20 > /** > diff --git a/udp.c b/udp.c > index 75edc20..35e3603 100644 > --- a/udp.c > +++ b/udp.c > @@ -133,11 +133,8 @@ static int udp_splice_init[IP_VERSIONS][NUM_PORTS]; > /* UDP header and data for inbound messages */ > static struct udp_payload_t udp_payload[UDP_MAX_FRAMES]; > =20 > -/* Ethernet header for IPv4 frames */ > -static struct ethhdr udp4_eth_hdr; > - > -/* Ethernet header for IPv6 frames */ > -static struct ethhdr udp6_eth_hdr; > +/* Ethernet headers for IPv4 and IPv6 frames */ > +static struct ethhdr udp_eth_hdr[UDP_MAX_FRAMES]; > =20 > /** > * struct udp_meta_t - Pre-cooked headers for UDP packets > @@ -212,10 +209,12 @@ void udp_portmap_clear(void) > * @eth_d: Ethernet destination address, NULL if unchanged > * @eth_s: Ethernet source address, NULL if unchanged > */ > -void udp_update_l2_buf(const unsigned char *eth_d, const unsigned char *= eth_s) > +void udp_update_l2_buf(const unsigned char *eth_d) > { > - eth_update_mac(&udp4_eth_hdr, eth_d, eth_s); > - eth_update_mac(&udp6_eth_hdr, eth_d, eth_s); > + int i; > + > + for (i =3D 0; i < UDP_MAX_FRAMES; i++) > + eth_update_mac(&udp_eth_hdr[i], eth_d, NULL); > } > =20 > /** > @@ -238,6 +237,7 @@ static void udp_iov_init_one(const struct ctx *c, siz= e_t i) > =20 > *siov =3D IOV_OF_LVALUE(payload->data); > =20 > + tiov[UDP_IOV_ETH] =3D IOV_OF_LVALUE(udp_eth_hdr[i]); > tiov[UDP_IOV_TAP] =3D tap_hdr_iov(c, &meta->taph); > tiov[UDP_IOV_PAYLOAD].iov_base =3D payload; > =20 > @@ -253,9 +253,6 @@ static void udp_iov_init(const struct ctx *c) > { > size_t i; > =20 > - udp4_eth_hdr.h_proto =3D htons_constant(ETH_P_IP); > - udp6_eth_hdr.h_proto =3D htons_constant(ETH_P_IPV6); > - > for (i =3D 0; i < UDP_MAX_FRAMES; i++) > udp_iov_init_one(c, i); > } > @@ -352,31 +349,34 @@ size_t udp_update_hdr6(struct ipv6hdr *ip6h, struct= udp_payload_t *bp, > * udp_tap_prepare() - Convert one datagram into a tap frame > * @mmh: Receiving mmsghdr array > * @idx: Index of the datagram to prepare > + * @tap_omac: MAC address of remote endpoint as seen from the guest > * @toside: Flowside for destination side > * @no_udp_csum: Do not set UDP checksum > */ > static void udp_tap_prepare(const struct mmsghdr *mmh, > - unsigned idx, const struct flowside *toside, > + unsigned int idx, > + const unsigned char *tap_omac, > + const struct flowside *toside, > bool no_udp_csum) > { > struct iovec (*tap_iov)[UDP_NUM_IOVS] =3D &udp_l2_iov[idx]; > struct udp_payload_t *bp =3D &udp_payload[idx]; > struct udp_meta_t *bm =3D &udp_meta[idx]; > + struct ethhdr *eh =3D (*tap_iov)[UDP_IOV_ETH].iov_base; > size_t l4len; > =20 > + eth_update_mac(eh, 0, tap_omac); s/0/NULL/ please. > if (!inany_v4(&toside->eaddr) || !inany_v4(&toside->oaddr)) { > l4len =3D udp_update_hdr6(&bm->ip6h, bp, toside, > mmh[idx].msg_len, no_udp_csum); > - tap_hdr_update(&bm->taph, l4len + sizeof(bm->ip6h) + > - sizeof(udp6_eth_hdr)); > - (*tap_iov)[UDP_IOV_ETH] =3D IOV_OF_LVALUE(udp6_eth_hdr); > + tap_hdr_update(&bm->taph, l4len + sizeof(bm->ip6h) + ETH_HLEN); s/ETH_HLEN/sizeof(*eh)/ > + eh->h_proto =3D htons_constant(ETH_P_IPV6); > (*tap_iov)[UDP_IOV_IP] =3D IOV_OF_LVALUE(bm->ip6h); > } else { > l4len =3D udp_update_hdr4(&bm->ip4h, bp, toside, > mmh[idx].msg_len, no_udp_csum); > - tap_hdr_update(&bm->taph, l4len + sizeof(bm->ip4h) + > - sizeof(udp4_eth_hdr)); > - (*tap_iov)[UDP_IOV_ETH] =3D IOV_OF_LVALUE(udp4_eth_hdr); > + tap_hdr_update(&bm->taph, l4len + sizeof(bm->ip4h) + ETH_HLEN); Ditto. > + eh->h_proto =3D htons_constant(ETH_P_IP); > (*tap_iov)[UDP_IOV_IP] =3D IOV_OF_LVALUE(bm->ip4h); > } > (*tap_iov)[UDP_IOV_PAYLOAD].iov_len =3D l4len; > @@ -801,13 +801,14 @@ static void udp_buf_sock_to_tap(const struct ctx *c= , int s, int n, > flow_sidx_t tosidx) > { > const struct flowside *toside =3D flowside_at_sidx(tosidx); > + const struct udp_flow *uflow =3D udp_at_sidx(tosidx); > int i; > =20 > if ((n =3D udp_sock_recv(c, s, udp_mh_recv, n)) <=3D 0) > return; > =20 > for (i =3D 0; i < n; i++) > - udp_tap_prepare(udp_mh_recv, i, toside, false); > + udp_tap_prepare(udp_mh_recv, i, uflow->f.tap_omac, toside, false); > =20 > tap_send_frames(c, &udp_l2_iov[0][0], UDP_NUM_IOVS, n); > } > diff --git a/udp.h b/udp.h > index 8f8531a..dd6e5ad 100644 > --- a/udp.h > +++ b/udp.h > @@ -21,7 +21,7 @@ int udp_sock_init(const struct ctx *c, int ns, const un= ion inany_addr *addr, > const char *ifname, in_port_t port); > int udp_init(struct ctx *c); > void udp_timer(struct ctx *c, const struct timespec *now); > -void udp_update_l2_buf(const unsigned char *eth_d, const unsigned char *= eth_s); > +void udp_update_l2_buf(const unsigned char *eth_d); > =20 > /** > * union udp_listen_epoll_ref - epoll reference for "listening" UDP sock= ets --=20 David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson --RNSSiAN+7ympUiEg Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEO+dNsU4E3yXUXRK2zQJF27ox2GcFAmimdzQACgkQzQJF27ox 2Ge3nA/7BCY8jY8nyfsRhDYMGTpBW5LsxTEhMGC7AwA2VqTXdXazzhAprlXLs7nF zrjLufTJk35Wbu0+5/vS3ADEyOJ4E2NK/padI9OkwpwNF2nevR2BYWXVsfH262NB taA+s8LsAplGII8XKOagPtYvHqQJCCK2JB+TOfrQQLc0SPmhyCuu91Q1lEU1ybh9 /n+ZKXtrmyhtnPebB63qoYGWlemw03YwZRgRlT/66y7AAlPdV1usqI4Qb1TZBr0L PHWlqaea2nBd8Id/wQX+TKjEH0xhtniw/pKbnUAuUJ8ZznEBZSoFiDn9m03xidm+ TvnDmxk1qcwChtKo/pgdA831zY9NZneMHDALNB2as8OW0w5104ziCPgzaOCLQLBn mz2pdRRXgeknC5oDWHSKqdLvGDdWaffsn2Al882lYiV8rcI2RSXSHCAhPD0+i//Y 3ApVGg4HUUVCAaochyF/B7+whblui6y0lg1khr5+E+JKafgNyL8K1tFjQtxgNN/Z rMp20Vt9096iKL02jyyEQksWT3UbD7tD6humboO5J6EmaATpH9CYLCjsaxfC6X2L /dAlQSaE3Rjbw7x58ML1dMFjKqfdUwaK22c6JQ1q2Ysst1lXmWjwNA5E15FgyXAT FGtHTJKtVUuCSnudKO8o4Hn6c5MHvSh0BRCRNesMeDnlNhyUmS8= =uGDH -----END PGP SIGNATURE----- --RNSSiAN+7ympUiEg--