From feb4900c25deabaf9b54760e40aea5e65499e987 Mon Sep 17 00:00:00 2001 From: Laurent Vivier Date: Wed, 6 Mar 2024 16:58:35 +1100 Subject: [PATCH] checksum: use csum_ip4_header() in udp.c and tcp.c We can find the same function to compute the IPv4 header checksum in tcp.c, udp.c and tap.c Use the function defined for tap.c, csum_ip4_header(), but with the code used in tcp.c and udp.c as it doesn't need a fully initialiazed IPv4 header, only protocol, tot_len, saddr and daddr. Signed-off-by: Laurent Vivier Reviewed-by: David Gibson Message-ID: <20240303135114.1023026-7-lvivier@redhat.com> [dwg: Fix weird cppcheck regression; it appears to be a problem in pre-existing code, but somehow this patch is exposing it] Signed-off-by: David Gibson Signed-off-by: Stefano Brivio --- checksum.c | 24 +++++++++++++++++++----- checksum.h | 3 ++- tap.c | 2 +- tcp.c | 24 +++--------------------- udp.c | 20 ++------------------ 5 files changed, 27 insertions(+), 46 deletions(-) diff --git a/checksum.c b/checksum.c index 643957b..1ac7975 100644 --- a/checksum.c +++ b/checksum.c @@ -57,6 +57,7 @@ #include #include "util.h" +#include "ip.h" #include "checksum.h" /* Checksums are optional for UDP over IPv4, so we usually just set @@ -114,13 +115,26 @@ uint16_t csum_fold(uint32_t sum) } /** - * csum_ip4_header() - Calculate and set IPv4 header checksum - * @ip4h: IPv4 header + * csum_ip4_header() - Calculate IPv4 header checksum + * @tot_len: IPv4 payload length (data + IP header, network order) + * @protocol: Protocol number (network order) + * @saddr: IPv4 source address (network order) + * @daddr: IPv4 destination address (network order) + * + * Return: 16-bit folded sum of the IPv4 header */ -void csum_ip4_header(struct iphdr *ip4h) +uint16_t csum_ip4_header(uint16_t tot_len, uint8_t protocol, + struct in_addr saddr, struct in_addr daddr) { - ip4h->check = 0; - ip4h->check = csum(ip4h, (size_t)ip4h->ihl * 4, 0); + uint32_t sum = L2_BUF_IP4_PSUM(protocol); + + sum += tot_len; + sum += (saddr.s_addr >> 16) & 0xffff; + sum += saddr.s_addr & 0xffff; + sum += (daddr.s_addr >> 16) & 0xffff; + sum += daddr.s_addr & 0xffff; + + return ~csum_fold(sum); } /** diff --git a/checksum.h b/checksum.h index cb80ab3..996f456 100644 --- a/checksum.h +++ b/checksum.h @@ -13,7 +13,8 @@ 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_ip4_header(struct iphdr *ip4h); +uint16_t csum_ip4_header(uint16_t tot_len, uint8_t protocol, + struct in_addr saddr, struct in_addr daddr); void csum_udp4(struct udphdr *udp4hr, struct in_addr saddr, struct in_addr daddr, const void *payload, size_t len); diff --git a/tap.c b/tap.c index d35d894..f971461 100644 --- a/tap.c +++ b/tap.c @@ -161,7 +161,7 @@ static void *tap_push_ip4h(char *buf, struct in_addr src, struct in_addr dst, ip4h->protocol = proto; ip4h->saddr = src.s_addr; ip4h->daddr = dst.s_addr; - csum_ip4_header(ip4h); + ip4h->check = csum_ip4_header(ip4h->tot_len, proto, src, dst); return ip4h + 1; } diff --git a/tcp.c b/tcp.c index e0588f9..7fb9dba 100644 --- a/tcp.c +++ b/tcp.c @@ -935,23 +935,6 @@ static void tcp_sock_set_bufsize(const struct ctx *c, int s) trace("TCP: failed to set SO_SNDBUF to %i", v); } -/** - * tcp_update_check_ip4() - Update IPv4 with variable parts from stored one - * @buf: L2 packet buffer with final IPv4 header - */ -static void tcp_update_check_ip4(struct tcp4_l2_buf_t *buf) -{ - uint32_t sum = L2_BUF_IP4_PSUM(IPPROTO_TCP); - - sum += buf->iph.tot_len; - sum += (buf->iph.saddr >> 16) & 0xffff; - sum += buf->iph.saddr & 0xffff; - sum += (buf->iph.daddr >> 16) & 0xffff; - sum += buf->iph.daddr & 0xffff; - - buf->iph.check = (uint16_t)~csum_fold(sum); -} - /** * tcp_update_check_tcp4() - Update TCP checksum from stored one * @buf: L2 packet buffer with final IPv4 header @@ -1394,10 +1377,9 @@ do { \ b->iph.saddr = a4->s_addr; b->iph.daddr = c->ip4.addr_seen.s_addr; - if (check) - b->iph.check = *check; - else - tcp_update_check_ip4(b); + b->iph.check = check ? *check : + csum_ip4_header(b->iph.tot_len, IPPROTO_TCP, + *a4, c->ip4.addr_seen); SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq); diff --git a/udp.c b/udp.c index 2b41a1b..fb8373b 100644 --- a/udp.c +++ b/udp.c @@ -275,23 +275,6 @@ static void udp_invert_portmap(struct udp_fwd_ports *fwd) } } -/** - * udp_update_check4() - Update checksum with variable parts from stored one - * @buf: L2 packet buffer with final IPv4 header - */ -static void udp_update_check4(struct udp4_l2_buf_t *buf) -{ - uint32_t sum = L2_BUF_IP4_PSUM(IPPROTO_UDP); - - sum += buf->iph.tot_len; - sum += (buf->iph.saddr >> 16) & 0xffff; - sum += buf->iph.saddr & 0xffff; - sum += (buf->iph.daddr >> 16) & 0xffff; - sum += buf->iph.daddr & 0xffff; - - buf->iph.check = (uint16_t)~csum_fold(sum); -} - /** * udp_update_l2_buf() - Update L2 buffers with Ethernet and IPv4 addresses * @eth_d: Ethernet destination address, NULL if unchanged @@ -619,7 +602,8 @@ static size_t udp_update_hdr4(const struct ctx *c, int n, in_port_t dstport, } b->iph.saddr = src->s_addr; - udp_update_check4(b); + b->iph.check = csum_ip4_header(b->iph.tot_len, IPPROTO_UDP, + *src, c->ip4.addr_seen); b->uh.source = b->s_in.sin_port; b->uh.dest = htons(dstport); b->uh.len = htons(udp4_l2_mh_sock[n].msg_len + sizeof(b->uh));