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ipvs: optimize checksums for apps
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 	Avoid full checksum calculation for apps that can provide
info whether csum was broken after payload mangling. For now only
ip_vs_ftp mangles payload and it updates the csum, so the full
recalculation is avoided for all packets.

 	Add CHECKSUM_UNNECESSARY for snat_handler (TCP and UDP).
It is needed to support SNAT from local address for the case
when csum is fully recalculated.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
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Julian Anastasov authored and Simon Horman committed Oct 21, 2010
1 parent 5bc9068 commit 8b27b10
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Showing 4 changed files with 66 additions and 15 deletions.
12 changes: 10 additions & 2 deletions include/net/ip_vs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -597,11 +597,19 @@ struct ip_vs_app {
__be16 port; /* port number in net order */
atomic_t usecnt; /* usage counter */

/* output hook: return false if can't linearize. diff set for TCP. */
/*
* output hook: Process packet in inout direction, diff set for TCP.
* Return: 0=Error, 1=Payload Not Mangled/Mangled but checksum is ok,
* 2=Mangled but checksum was not updated
*/
int (*pkt_out)(struct ip_vs_app *, struct ip_vs_conn *,
struct sk_buff *, int *diff);

/* input hook: return false if can't linearize. diff set for TCP. */
/*
* input hook: Process packet in outin direction, diff set for TCP.
* Return: 0=Error, 1=Payload Not Mangled/Mangled but checksum is ok,
* 2=Mangled but checksum was not updated
*/
int (*pkt_in)(struct ip_vs_app *, struct ip_vs_conn *,
struct sk_buff *, int *diff);

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7 changes: 6 additions & 1 deletion net/netfilter/ipvs/ip_vs_ftp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -242,9 +242,14 @@ static int ip_vs_ftp_out(struct ip_vs_app *app, struct ip_vs_conn *cp,
ret = nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
start-data, end-start,
buf, buf_len);
if (ret)
if (ret) {
ip_vs_nfct_expect_related(skb, ct, n_cp,
IPPROTO_TCP, 0, 0);
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = CHECKSUM_UNNECESSARY;
/* csum is updated */
ret = 1;
}
}

/*
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31 changes: 25 additions & 6 deletions net/netfilter/ipvs/ip_vs_proto_tcp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -120,6 +120,7 @@ tcp_snat_handler(struct sk_buff *skb,
struct tcphdr *tcph;
unsigned int tcphoff;
int oldlen;
int payload_csum = 0;

#ifdef CONFIG_IP_VS_IPV6
if (cp->af == AF_INET6)
Expand All @@ -134,13 +135,20 @@ tcp_snat_handler(struct sk_buff *skb,
return 0;

if (unlikely(cp->app != NULL)) {
int ret;

/* Some checks before mangling */
if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
return 0;

/* Call application helper if needed */
if (!ip_vs_app_pkt_out(cp, skb))
if (!(ret = ip_vs_app_pkt_out(cp, skb)))
return 0;
/* ret=2: csum update is needed after payload mangling */
if (ret == 1)
oldlen = skb->len - tcphoff;
else
payload_csum = 1;
}

tcph = (void *)skb_network_header(skb) + tcphoff;
Expand All @@ -151,12 +159,13 @@ tcp_snat_handler(struct sk_buff *skb,
tcp_partial_csum_update(cp->af, tcph, &cp->daddr, &cp->vaddr,
htons(oldlen),
htons(skb->len - tcphoff));
} else if (!cp->app) {
} else if (!payload_csum) {
/* Only port and addr are changed, do fast csum update */
tcp_fast_csum_update(cp->af, tcph, &cp->daddr, &cp->vaddr,
cp->dport, cp->vport);
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = CHECKSUM_NONE;
skb->ip_summed = (cp->app && pp->csum_check) ?
CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
} else {
/* full checksum calculation */
tcph->check = 0;
Expand All @@ -174,6 +183,7 @@ tcp_snat_handler(struct sk_buff *skb,
skb->len - tcphoff,
cp->protocol,
skb->csum);
skb->ip_summed = CHECKSUM_UNNECESSARY;

IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
pp->name, tcph->check,
Expand All @@ -190,6 +200,7 @@ tcp_dnat_handler(struct sk_buff *skb,
struct tcphdr *tcph;
unsigned int tcphoff;
int oldlen;
int payload_csum = 0;

#ifdef CONFIG_IP_VS_IPV6
if (cp->af == AF_INET6)
Expand All @@ -204,6 +215,8 @@ tcp_dnat_handler(struct sk_buff *skb,
return 0;

if (unlikely(cp->app != NULL)) {
int ret;

/* Some checks before mangling */
if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
return 0;
Expand All @@ -212,8 +225,13 @@ tcp_dnat_handler(struct sk_buff *skb,
* Attempt ip_vs_app call.
* It will fix ip_vs_conn and iph ack_seq stuff
*/
if (!ip_vs_app_pkt_in(cp, skb))
if (!(ret = ip_vs_app_pkt_in(cp, skb)))
return 0;
/* ret=2: csum update is needed after payload mangling */
if (ret == 1)
oldlen = skb->len - tcphoff;
else
payload_csum = 1;
}

tcph = (void *)skb_network_header(skb) + tcphoff;
Expand All @@ -226,12 +244,13 @@ tcp_dnat_handler(struct sk_buff *skb,
tcp_partial_csum_update(cp->af, tcph, &cp->vaddr, &cp->daddr,
htons(oldlen),
htons(skb->len - tcphoff));
} else if (!cp->app) {
} else if (!payload_csum) {
/* Only port and addr are changed, do fast csum update */
tcp_fast_csum_update(cp->af, tcph, &cp->vaddr, &cp->daddr,
cp->vport, cp->dport);
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = CHECKSUM_NONE;
skb->ip_summed = (cp->app && pp->csum_check) ?
CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
} else {
/* full checksum calculation */
tcph->check = 0;
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31 changes: 25 additions & 6 deletions net/netfilter/ipvs/ip_vs_proto_udp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -121,6 +121,7 @@ udp_snat_handler(struct sk_buff *skb,
struct udphdr *udph;
unsigned int udphoff;
int oldlen;
int payload_csum = 0;

#ifdef CONFIG_IP_VS_IPV6
if (cp->af == AF_INET6)
Expand All @@ -135,15 +136,22 @@ udp_snat_handler(struct sk_buff *skb,
return 0;

if (unlikely(cp->app != NULL)) {
int ret;

/* Some checks before mangling */
if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
return 0;

/*
* Call application helper if needed
*/
if (!ip_vs_app_pkt_out(cp, skb))
if (!(ret = ip_vs_app_pkt_out(cp, skb)))
return 0;
/* ret=2: csum update is needed after payload mangling */
if (ret == 1)
oldlen = skb->len - udphoff;
else
payload_csum = 1;
}

udph = (void *)skb_network_header(skb) + udphoff;
Expand All @@ -156,12 +164,13 @@ udp_snat_handler(struct sk_buff *skb,
udp_partial_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
htons(oldlen),
htons(skb->len - udphoff));
} else if (!cp->app && (udph->check != 0)) {
} else if (!payload_csum && (udph->check != 0)) {
/* Only port and addr are changed, do fast csum update */
udp_fast_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
cp->dport, cp->vport);
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = CHECKSUM_NONE;
skb->ip_summed = (cp->app && pp->csum_check) ?
CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
} else {
/* full checksum calculation */
udph->check = 0;
Expand All @@ -181,6 +190,7 @@ udp_snat_handler(struct sk_buff *skb,
skb->csum);
if (udph->check == 0)
udph->check = CSUM_MANGLED_0;
skb->ip_summed = CHECKSUM_UNNECESSARY;
IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
pp->name, udph->check,
(char*)&(udph->check) - (char*)udph);
Expand All @@ -196,6 +206,7 @@ udp_dnat_handler(struct sk_buff *skb,
struct udphdr *udph;
unsigned int udphoff;
int oldlen;
int payload_csum = 0;

#ifdef CONFIG_IP_VS_IPV6
if (cp->af == AF_INET6)
Expand All @@ -210,6 +221,8 @@ udp_dnat_handler(struct sk_buff *skb,
return 0;

if (unlikely(cp->app != NULL)) {
int ret;

/* Some checks before mangling */
if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
return 0;
Expand All @@ -218,8 +231,13 @@ udp_dnat_handler(struct sk_buff *skb,
* Attempt ip_vs_app call.
* It will fix ip_vs_conn
*/
if (!ip_vs_app_pkt_in(cp, skb))
if (!(ret = ip_vs_app_pkt_in(cp, skb)))
return 0;
/* ret=2: csum update is needed after payload mangling */
if (ret == 1)
oldlen = skb->len - udphoff;
else
payload_csum = 1;
}

udph = (void *)skb_network_header(skb) + udphoff;
Expand All @@ -232,12 +250,13 @@ udp_dnat_handler(struct sk_buff *skb,
udp_partial_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,
htons(oldlen),
htons(skb->len - udphoff));
} else if (!cp->app && (udph->check != 0)) {
} else if (!payload_csum && (udph->check != 0)) {
/* Only port and addr are changed, do fast csum update */
udp_fast_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,
cp->vport, cp->dport);
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = CHECKSUM_NONE;
skb->ip_summed = (cp->app && pp->csum_check) ?
CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
} else {
/* full checksum calculation */
udph->check = 0;
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