On Mon, Sep 16, 2024 at 02:16:00PM +0200, Laurent Vivier wrote:We can need not to set the UDP checksum. Add a parameter to udp_update_hdr4() and udp_update_hdr6() to disable it. Signed-off-by: Laurent Vivier <lvivier(a)redhat.com> --- udp.c | 41 +++++++++++++++++++++++++++++++---------- 1 file changed, 31 insertions(+), 10 deletions(-) diff --git a/udp.c b/udp.c index 2ba00c9c20a8..64a0d9f9dba2 100644 --- a/udp.c +++ b/udp.c @@ -298,11 +298,13 @@ static void udp_splice_send(const struct ctx *c, size_t start, size_t n, * @bp: Pointer to udp_payload_t to update * @toside: Flowside for destination side * @dlen: Length of UDP payload + * @no_udp_csum: Do not set UPD checksums/UPD/UDP/g :) Otherwise LGTM.* * Return: size of IPv4 payload (UDP header + data) */ static size_t udp_update_hdr4(struct iphdr *ip4h, struct udp_payload_t *bp, - const struct flowside *toside, size_t dlen) + const struct flowside *toside, size_t dlen, + bool no_udp_csum) { const struct in_addr *src = inany_v4(&toside->oaddr); const struct in_addr *dst = inany_v4(&toside->eaddr); @@ -319,7 +321,10 @@ static size_t udp_update_hdr4(struct iphdr *ip4h, struct udp_payload_t *bp, bp->uh.source = htons(toside->oport); bp->uh.dest = htons(toside->eport); bp->uh.len = htons(l4len); - csum_udp4(&bp->uh, *src, *dst, bp->data, dlen); + if (no_udp_csum) + bp->uh.check = 0; + else + csum_udp4(&bp->uh, *src, *dst, bp->data, dlen); return l4len; } @@ -330,11 +335,13 @@ static size_t udp_update_hdr4(struct iphdr *ip4h, struct udp_payload_t *bp, * @bp: Pointer to udp_payload_t to update * @toside: Flowside for destination side * @dlen: Length of UDP payload + * @no_udp_csum: Do not set UPD checksum * * Return: size of IPv6 payload (UDP header + data) */ static size_t udp_update_hdr6(struct ipv6hdr *ip6h, struct udp_payload_t *bp, - const struct flowside *toside, size_t dlen) + const struct flowside *toside, size_t dlen, + bool no_udp_csum) { uint16_t l4len = dlen + sizeof(bp->uh); @@ -348,7 +355,16 @@ static size_t udp_update_hdr6(struct ipv6hdr *ip6h, struct udp_payload_t *bp, bp->uh.source = htons(toside->oport); bp->uh.dest = htons(toside->eport); bp->uh.len = ip6h->payload_len; - csum_udp6(&bp->uh, &toside->oaddr.a6, &toside->eaddr.a6, bp->data, dlen); + if (no_udp_csum) { + /* O is an invalid checksum for UDP IPv6 and dropped by + * the kernel stack, even if the checksum is disabled by virtio + * flags. We need to put any non-zero value here. + */ + bp->uh.check = 0xffff; + } else { + csum_udp6(&bp->uh, &toside->oaddr.a6, &toside->eaddr.a6, + bp->data, dlen); + } return l4len; } @@ -358,9 +374,11 @@ static size_t udp_update_hdr6(struct ipv6hdr *ip6h, struct udp_payload_t *bp, * @mmh: Receiving mmsghdr array * @idx: Index of the datagram to prepare * @toside: Flowside for destination side + * @no_udp_csum: Do not set UPD checksum */ -static void udp_tap_prepare(const struct mmsghdr *mmh, unsigned idx, - const struct flowside *toside) +static void udp_tap_prepare(const struct mmsghdr *mmh, + unsigned idx, const struct flowside *toside, + bool no_udp_csum) { struct iovec (*tap_iov)[UDP_NUM_IOVS] = &udp_l2_iov[idx]; struct udp_payload_t *bp = &udp_payload[idx]; @@ -368,13 +386,15 @@ static void udp_tap_prepare(const struct mmsghdr *mmh, unsigned idx, size_t l4len; if (!inany_v4(&toside->eaddr) || !inany_v4(&toside->oaddr)) { - l4len = udp_update_hdr6(&bm->ip6h, bp, toside, mmh[idx].msg_len); + l4len = 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] = IOV_OF_LVALUE(udp6_eth_hdr); (*tap_iov)[UDP_IOV_IP] = IOV_OF_LVALUE(bm->ip6h); } else { - l4len = udp_update_hdr4(&bm->ip4h, bp, toside, mmh[idx].msg_len); + l4len = 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] = IOV_OF_LVALUE(udp4_eth_hdr); @@ -565,7 +585,8 @@ void udp_listen_sock_handler(const struct ctx *c, union epoll_ref ref, udp_splice_prepare(udp_mh_recv, i); } else if (batchpif == PIF_TAP) { udp_tap_prepare(udp_mh_recv, i, - flowside_at_sidx(batchsidx)); + flowside_at_sidx(batchsidx), + false); } if (++i >= n) @@ -636,7 +657,7 @@ void udp_reply_sock_handler(const struct ctx *c, union epoll_ref ref, if (pif_is_socket(topif)) udp_splice_prepare(udp_mh_recv, i); else if (topif == PIF_TAP) - udp_tap_prepare(udp_mh_recv, i, toside); + udp_tap_prepare(udp_mh_recv, i, toside, false); /* Restore sockaddr length clobbered by recvmsg() */ udp_mh_recv[i].msg_hdr.msg_namelen = sizeof(udp_meta[i].s_in); }-- 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