checksum: introduce functions to compute the header part checksum for TCP/UDP
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). We add two functions, proto_ipv4_header_psum() and proto_ipv6_header_psum(), to compute the checksum of the IP header part. Signed-off-by: Laurent Vivier <lvivier@redhat.com> Message-ID: <20240303135114.1023026-8-lvivier@redhat.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Laurent Vivier
Stefano Brivio
parent
feb4900c25
commit
7df624e79a
4 changed files with 90 additions and 50 deletions
67
checksum.c
67
checksum.c
|
|
@ -137,6 +137,29 @@ uint16_t csum_ip4_header(uint16_t tot_len, uint8_t protocol,
|
|||
return ~csum_fold(sum);
|
||||
}
|
||||
|
||||
/**
|
||||
* proto_ipv4_header_psum() - Calculates the partial checksum of an
|
||||
* IPv4 header for UDP or TCP
|
||||
* @tot_len: IPv4 Payload length (host order)
|
||||
* @proto: Protocol number (host order)
|
||||
* @saddr: Source address (network order)
|
||||
* @daddr: Destination address (network order)
|
||||
* Returns: Partial checksum of the IPv4 header
|
||||
*/
|
||||
uint32_t proto_ipv4_header_psum(uint16_t tot_len, uint8_t protocol,
|
||||
struct in_addr saddr, struct in_addr daddr)
|
||||
{
|
||||
uint32_t psum = htons(protocol);
|
||||
|
||||
psum += (saddr.s_addr >> 16) & 0xffff;
|
||||
psum += saddr.s_addr & 0xffff;
|
||||
psum += (daddr.s_addr >> 16) & 0xffff;
|
||||
psum += daddr.s_addr & 0xffff;
|
||||
psum += htons(tot_len);
|
||||
|
||||
return psum;
|
||||
}
|
||||
|
||||
/**
|
||||
* csum_udp4() - Calculate and set checksum for a UDP over IPv4 packet
|
||||
* @udp4hr: UDP header, initialised apart from checksum
|
||||
|
|
@ -153,14 +176,10 @@ void csum_udp4(struct udphdr *udp4hr,
|
|||
udp4hr->check = 0;
|
||||
|
||||
if (UDP4_REAL_CHECKSUMS) {
|
||||
/* UNTESTED: if we did want real UDPv4 checksums, this
|
||||
* is roughly what we'd need */
|
||||
uint32_t psum = 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 += sum_16b(udp4hr, sizeof(*udp4hr));
|
||||
uint16_t tot_len = len + sizeof(struct udphdr);
|
||||
uint32_t psum = proto_ipv4_header_psum(tot_len, IPPROTO_UDP,
|
||||
saddr, daddr);
|
||||
psum = csum_unfolded(udp4hr, sizeof(struct udphdr), psum);
|
||||
udp4hr->check = csum(payload, len, psum);
|
||||
}
|
||||
}
|
||||
|
|
@ -183,6 +202,27 @@ void csum_icmp4(struct icmphdr *icmp4hr, const void *payload, size_t len)
|
|||
icmp4hr->checksum = csum(payload, len, psum);
|
||||
}
|
||||
|
||||
/**
|
||||
* proto_ipv6_header_psum() - Calculates the partial checksum of an
|
||||
* IPv6 header for UDP or TCP
|
||||
* @payload_len: IPv6 payload length (host order)
|
||||
* @proto: Protocol number (host order)
|
||||
* @saddr: Source address (network order)
|
||||
* @daddr: Destination address (network order)
|
||||
* Returns: Partial checksum of the IPv6 header
|
||||
*/
|
||||
uint32_t proto_ipv6_header_psum(uint16_t payload_len, uint8_t protocol,
|
||||
const struct in6_addr *saddr,
|
||||
const struct in6_addr *daddr)
|
||||
{
|
||||
uint32_t sum = htons(protocol) + htons(payload_len);
|
||||
|
||||
sum += sum_16b(saddr, sizeof(*saddr));
|
||||
sum += 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
|
||||
|
|
@ -193,14 +233,11 @@ 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 = sum_16b(saddr, sizeof(*saddr)) +
|
||||
sum_16b(daddr, sizeof(*daddr)) +
|
||||
htons(len + sizeof(*udp6hr)) + htons(IPPROTO_UDP);
|
||||
|
||||
uint32_t psum = proto_ipv6_header_psum(len + sizeof(struct udphdr),
|
||||
IPPROTO_UDP, saddr, daddr);
|
||||
udp6hr->check = 0;
|
||||
/* Add in partial checksum for the UDP header alone */
|
||||
psum += sum_16b(udp6hr, sizeof(*udp6hr));
|
||||
|
||||
psum = csum_unfolded(udp6hr, sizeof(struct udphdr), psum);
|
||||
udp6hr->check = csum(payload, len, psum);
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -15,10 +15,15 @@ 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,
|
||||
struct in_addr saddr, struct in_addr daddr);
|
||||
uint32_t proto_ipv4_header_psum(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);
|
||||
void csum_icmp4(struct icmphdr *icmp4hr, const void *payload, size_t len);
|
||||
uint32_t proto_ipv6_header_psum(uint16_t payload_len, uint8_t protocol,
|
||||
const struct in6_addr *saddr,
|
||||
const 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);
|
||||
|
|
|
|||
50
tcp.c
50
tcp.c
|
|
@ -937,41 +937,33 @@ 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
|
||||
* @iph: IPv4 header
|
||||
* @th: TCP header followed by TCP payload
|
||||
*/
|
||||
static void tcp_update_check_tcp4(struct tcp4_l2_buf_t *buf)
|
||||
static void tcp_update_check_tcp4(const struct iphdr *iph, struct tcphdr *th)
|
||||
{
|
||||
uint16_t tlen = ntohs(buf->iph.tot_len) - 20;
|
||||
uint32_t sum = htons(IPPROTO_TCP);
|
||||
uint16_t tlen = ntohs(iph->tot_len) - sizeof(struct iphdr);
|
||||
struct in_addr saddr = { .s_addr = iph->saddr };
|
||||
struct in_addr daddr = { .s_addr = iph->daddr };
|
||||
uint32_t sum = proto_ipv4_header_psum(tlen, IPPROTO_TCP, saddr, daddr);
|
||||
|
||||
sum += (buf->iph.saddr >> 16) & 0xffff;
|
||||
sum += buf->iph.saddr & 0xffff;
|
||||
sum += (buf->iph.daddr >> 16) & 0xffff;
|
||||
sum += buf->iph.daddr & 0xffff;
|
||||
sum += htons(ntohs(buf->iph.tot_len) - 20);
|
||||
|
||||
buf->th.check = 0;
|
||||
buf->th.check = csum(&buf->th, tlen, sum);
|
||||
th->check = 0;
|
||||
th->check = csum(th, tlen, sum);
|
||||
}
|
||||
|
||||
/**
|
||||
* tcp_update_check_tcp6() - Calculate TCP checksum for IPv6
|
||||
* @buf: L2 packet buffer with final IPv6 header
|
||||
* @ip6h: IPv6 header
|
||||
* @th: TCP header followed by TCP payload
|
||||
*/
|
||||
static void tcp_update_check_tcp6(struct tcp6_l2_buf_t *buf)
|
||||
static void tcp_update_check_tcp6(struct ipv6hdr *ip6h, struct tcphdr *th)
|
||||
{
|
||||
int len = ntohs(buf->ip6h.payload_len) + sizeof(struct ipv6hdr);
|
||||
uint16_t payload_len = ntohs(ip6h->payload_len);
|
||||
uint32_t sum = proto_ipv6_header_psum(payload_len, IPPROTO_TCP,
|
||||
&ip6h->saddr, &ip6h->daddr);
|
||||
|
||||
buf->ip6h.hop_limit = IPPROTO_TCP;
|
||||
buf->ip6h.version = 0;
|
||||
buf->ip6h.nexthdr = 0;
|
||||
|
||||
buf->th.check = 0;
|
||||
buf->th.check = csum(&buf->ip6h, len, 0);
|
||||
|
||||
buf->ip6h.hop_limit = 255;
|
||||
buf->ip6h.version = 6;
|
||||
buf->ip6h.nexthdr = IPPROTO_TCP;
|
||||
th->check = 0;
|
||||
th->check = csum(th, payload_len, sum);
|
||||
}
|
||||
|
||||
/**
|
||||
|
|
@ -1383,7 +1375,7 @@ do { \
|
|||
|
||||
SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq);
|
||||
|
||||
tcp_update_check_tcp4(b);
|
||||
tcp_update_check_tcp4(&b->iph, &b->th);
|
||||
|
||||
tlen = tap_iov_len(c, &b->taph, ip_len);
|
||||
} else {
|
||||
|
|
@ -1402,7 +1394,11 @@ do { \
|
|||
|
||||
SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq);
|
||||
|
||||
tcp_update_check_tcp6(b);
|
||||
tcp_update_check_tcp6(&b->ip6h, &b->th);
|
||||
|
||||
b->ip6h.hop_limit = 255;
|
||||
b->ip6h.version = 6;
|
||||
b->ip6h.nexthdr = IPPROTO_TCP;
|
||||
|
||||
b->ip6h.flow_lbl[0] = (conn->sock >> 16) & 0xf;
|
||||
b->ip6h.flow_lbl[1] = (conn->sock >> 8) & 0xff;
|
||||
|
|
|
|||
18
udp.c
18
udp.c
|
|
@ -625,6 +625,7 @@ static size_t udp_update_hdr6(const struct ctx *c, int n, in_port_t dstport,
|
|||
{
|
||||
struct udp6_l2_buf_t *b = &udp6_l2_buf[n];
|
||||
const struct in6_addr *src, *dst;
|
||||
uint16_t payload_len;
|
||||
in_port_t src_port;
|
||||
size_t ip_len;
|
||||
|
||||
|
|
@ -634,7 +635,8 @@ static size_t udp_update_hdr6(const struct ctx *c, int n, in_port_t dstport,
|
|||
|
||||
ip_len = udp6_l2_mh_sock[n].msg_len + sizeof(b->ip6h) + sizeof(b->uh);
|
||||
|
||||
b->ip6h.payload_len = htons(udp6_l2_mh_sock[n].msg_len + sizeof(b->uh));
|
||||
payload_len = udp6_l2_mh_sock[n].msg_len + sizeof(b->uh);
|
||||
b->ip6h.payload_len = htons(payload_len);
|
||||
|
||||
if (IN6_IS_ADDR_LINKLOCAL(src)) {
|
||||
dst = &c->ip6.addr_ll_seen;
|
||||
|
|
@ -670,17 +672,17 @@ static size_t udp_update_hdr6(const struct ctx *c, int n, in_port_t dstport,
|
|||
}
|
||||
b->ip6h.daddr = *dst;
|
||||
b->ip6h.saddr = *src;
|
||||
b->ip6h.version = 6;
|
||||
b->ip6h.nexthdr = IPPROTO_UDP;
|
||||
b->ip6h.hop_limit = 255;
|
||||
|
||||
b->uh.source = b->s_in6.sin6_port;
|
||||
b->uh.dest = htons(dstport);
|
||||
b->uh.len = b->ip6h.payload_len;
|
||||
|
||||
b->ip6h.hop_limit = IPPROTO_UDP;
|
||||
b->ip6h.version = b->ip6h.nexthdr = b->uh.check = 0;
|
||||
b->uh.check = csum(&b->ip6h, ip_len, 0);
|
||||
b->ip6h.version = 6;
|
||||
b->ip6h.nexthdr = IPPROTO_UDP;
|
||||
b->ip6h.hop_limit = 255;
|
||||
b->uh.check = 0;
|
||||
b->uh.check = csum(&b->uh, payload_len,
|
||||
proto_ipv6_header_psum(payload_len, IPPROTO_UDP,
|
||||
src, dst));
|
||||
|
||||
return tap_iov_len(c, &b->taph, ip_len);
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in a new issue