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[NETFILTER]: Add partial checksum validation helper 

Move the UDP-Lite conntrack checksum validation to a generic helper
similar to nf_checksum() and make it fall back to nf_checksum()
in case the full packet is to be checksummed and hardware checksums
are available. This is to be used by DCCP conntrack, which also
needs to verify partial checksums.

Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Patrick McHardy 2008-03-20 15:15:53 +01:00
parent 6185f870e2
commit d63a650736
4 changed files with 94 additions and 40 deletions
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22
include/linux/netfilter.h
View File

@ -234,6 +234,11 @@ struct nf_afinfo {
unsigned short family;
__sum16 (*checksum)(struct sk_buff *skb, unsigned int hook,
unsigned int dataoff, u_int8_t protocol);
__sum16 (*checksum_partial)(struct sk_buff *skb,
unsigned int hook,
unsigned int dataoff,
unsigned int len,
u_int8_t protocol);
int (*route)(struct dst_entry **dst, struct flowi *fl);
void (*saveroute)(const struct sk_buff *skb,
struct nf_queue_entry *entry);
@ -263,6 +268,23 @@ nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
return csum;
}
static inline __sum16
nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
unsigned int dataoff, unsigned int len,
u_int8_t protocol, unsigned short family)
{
const struct nf_afinfo *afinfo;
__sum16 csum = 0;
rcu_read_lock();
afinfo = nf_get_afinfo(family);
if (afinfo)
csum = afinfo->checksum_partial(skb, hook, dataoff, len,
protocol);
rcu_read_unlock();
return csum;
}
extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);

37
net/ipv4/netfilter.c
View File

@ -182,21 +182,44 @@ __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
}
return csum;
}
EXPORT_SYMBOL(nf_ip_checksum);
static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
unsigned int dataoff, unsigned int len,
u_int8_t protocol)
{
const struct iphdr *iph = ip_hdr(skb);
__sum16 csum = 0;
switch (skb->ip_summed) {
case CHECKSUM_COMPLETE:
if (len == skb->len - dataoff)
return nf_ip_checksum(skb, hook, dataoff, protocol);
/* fall through */
case CHECKSUM_NONE:
skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
skb->len - dataoff, 0);
skb->ip_summed = CHECKSUM_NONE;
csum = __skb_checksum_complete_head(skb, dataoff + len);
if (!csum)
skb->ip_summed = CHECKSUM_UNNECESSARY;
}
return csum;
}
static int nf_ip_route(struct dst_entry **dst, struct flowi *fl)
{
return ip_route_output_key(&init_net, (struct rtable **)dst, fl);
}
static const struct nf_afinfo nf_ip_afinfo = {
.family = AF_INET,
.checksum = nf_ip_checksum,
.route = nf_ip_route,
.saveroute = nf_ip_saveroute,
.reroute = nf_ip_reroute,
.route_key_size = sizeof(struct ip_rt_info),
.family = AF_INET,
.checksum = nf_ip_checksum,
.checksum_partial = nf_ip_checksum_partial,
.route = nf_ip_route,
.saveroute = nf_ip_saveroute,
.reroute = nf_ip_reroute,
.route_key_size = sizeof(struct ip_rt_info),
};
static int ipv4_netfilter_init(void)

42
net/ipv6/netfilter.c
View File

@ -121,16 +121,44 @@ __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
}
return csum;
}
EXPORT_SYMBOL(nf_ip6_checksum);
static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
unsigned int dataoff, unsigned int len,
u_int8_t protocol)
{
struct ipv6hdr *ip6h = ipv6_hdr(skb);
__wsum hsum;
__sum16 csum = 0;
switch (skb->ip_summed) {
case CHECKSUM_COMPLETE:
if (len == skb->len - dataoff)
return nf_ip6_checksum(skb, hook, dataoff, protocol);
/* fall through */
case CHECKSUM_NONE:
hsum = skb_checksum(skb, 0, dataoff, 0);
skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
&ip6h->daddr,
skb->len - dataoff,
protocol,
csum_sub(0, hsum)));
skb->ip_summed = CHECKSUM_NONE;
csum = __skb_checksum_complete_head(skb, dataoff + len);
if (!csum)
skb->ip_summed = CHECKSUM_UNNECESSARY;
}
return csum;
};
static const struct nf_afinfo nf_ip6_afinfo = {
.family = AF_INET6,
.checksum = nf_ip6_checksum,
.route = nf_ip6_route,
.saveroute = nf_ip6_saveroute,
.reroute = nf_ip6_reroute,
.route_key_size = sizeof(struct ip6_rt_info),
.family = AF_INET6,
.checksum = nf_ip6_checksum,
.checksum_partial = nf_ip6_checksum_partial,
.route = nf_ip6_route,
.saveroute = nf_ip6_saveroute,
.reroute = nf_ip6_reroute,
.route_key_size = sizeof(struct ip6_rt_info),
};
int __init ipv6_netfilter_init(void)

33
net/netfilter/nf_conntrack_proto_udplite.c
View File

@ -127,32 +127,13 @@ static int udplite_error(struct sk_buff *skb, unsigned int dataoff,
}
/* Checksum invalid? Ignore. */
if (nf_conntrack_checksum && !skb_csum_unnecessary(skb) &&
hooknum == NF_INET_PRE_ROUTING) {
if (pf == PF_INET) {
struct iphdr *iph = ip_hdr(skb);
skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
udplen, IPPROTO_UDPLITE, 0);
} else {
struct ipv6hdr *ipv6h = ipv6_hdr(skb);
__wsum hsum = skb_checksum(skb, 0, dataoff, 0);
skb->csum = ~csum_unfold(
csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
udplen, IPPROTO_UDPLITE,
csum_sub(0, hsum)));
}
skb->ip_summed = CHECKSUM_NONE;
if (__skb_checksum_complete_head(skb, dataoff + cscov)) {
if (LOG_INVALID(IPPROTO_UDPLITE))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_udplite: bad UDPLite "
"checksum ");
return -NF_ACCEPT;
}
skb->ip_summed = CHECKSUM_UNNECESSARY;
if (nf_conntrack_checksum && hooknum == NF_INET_PRE_ROUTING &&
nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_UDP,
pf)) {
if (LOG_INVALID(IPPROTO_UDPLITE))
nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
"nf_ct_udplite: bad UDPLite checksum ");
return -NF_ACCEPT;
}
return NF_ACCEPT;