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[UDP]: Cleanup UDP encapsulation code
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This cleanup fell out after adding L2TP support where a new encap_rcv
funcptr was added to struct udp_sock. Have XFRM use the new encap_rcv
funcptr, which allows us to move the XFRM encap code from udp.c into
xfrm4_input.c.

Make xfrm4_rcv_encap() static since it is no longer called externally.

Signed-off-by: James Chapman <jchapman@katalix.com>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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James Chapman authored and David S. Miller committed Jul 11, 2007
1 parent 93cce3d commit 067b207
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Showing 3 changed files with 133 additions and 142 deletions.
5 changes: 3 additions & 2 deletions include/net/xfrm.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1003,7 +1003,7 @@ extern int xfrm6_find_1stfragopt(struct xfrm_state *x, struct sk_buff *skb,
u8 **prevhdr);

#ifdef CONFIG_XFRM
extern int xfrm4_rcv_encap(struct sk_buff *skb, __u16 encap_type);
extern int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb);
extern int xfrm_user_policy(struct sock *sk, int optname, u8 __user *optval, int optlen);
extern int xfrm_dst_lookup(struct xfrm_dst **dst, struct flowi *fl, unsigned short family);
#else
Expand All @@ -1012,12 +1012,13 @@ static inline int xfrm_user_policy(struct sock *sk, int optname, u8 __user *optv
return -ENOPROTOOPT;
}

static inline int xfrm4_rcv_encap(struct sk_buff *skb, __u16 encap_type)
static inline int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
{
/* should not happen */
kfree_skb(skb);
return 0;
}

static inline int xfrm_dst_lookup(struct xfrm_dst **dst, struct flowi *fl, unsigned short family)
{
return -EINVAL;
Expand Down
156 changes: 24 additions & 132 deletions net/ipv4/udp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -920,108 +920,6 @@ int udp_disconnect(struct sock *sk, int flags)
return 0;
}

/* return:
* 1 if the UDP system should process it
* 0 if we should drop this packet
* -1 if it should get processed by xfrm4_rcv_encap
* -2 if it should get processed by l2tp
*/
static int udp_encap_rcv(struct sock * sk, struct sk_buff *skb)
{
struct udp_sock *up = udp_sk(sk);
struct udphdr *uh;
struct iphdr *iph;
int iphlen, len;

__u8 *udpdata;
__be32 *udpdata32;
__u16 encap_type = up->encap_type;

/* if we're overly short, let UDP handle it */
len = skb->len - sizeof(struct udphdr);
if (len <= 0)
return 1;

/* if this is not encapsulated socket, then just return now */
if (!encap_type)
return 1;

/* If this is a paged skb, make sure we pull up
* whatever data we need to look at. */
if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
return 1;

/* Now we can get the pointers */
uh = udp_hdr(skb);
udpdata = (__u8 *)uh + sizeof(struct udphdr);
udpdata32 = (__be32 *)udpdata;

switch (encap_type) {
default:
case UDP_ENCAP_ESPINUDP:
/* Check if this is a keepalive packet. If so, eat it. */
if (len == 1 && udpdata[0] == 0xff) {
return 0;
} else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
/* ESP Packet without Non-ESP header */
len = sizeof(struct udphdr);
} else
/* Must be an IKE packet.. pass it through */
return 1;
break;
case UDP_ENCAP_ESPINUDP_NON_IKE:
/* Check if this is a keepalive packet. If so, eat it. */
if (len == 1 && udpdata[0] == 0xff) {
return 0;
} else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
udpdata32[0] == 0 && udpdata32[1] == 0) {

/* ESP Packet with Non-IKE marker */
len = sizeof(struct udphdr) + 2 * sizeof(u32);
} else
/* Must be an IKE packet.. pass it through */
return 1;
break;
case UDP_ENCAP_L2TPINUDP:
/* Let caller know to send this to l2tp */
return -2;
}

#ifndef CONFIG_XFRM
return 1;
#else
/* At this point we are sure that this is an ESPinUDP packet,
* so we need to remove 'len' bytes from the packet (the UDP
* header and optional ESP marker bytes) and then modify the
* protocol to ESP, and then call into the transform receiver.
*/
if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
return 0;

/* Now we can update and verify the packet length... */
iph = ip_hdr(skb);
iphlen = iph->ihl << 2;
iph->tot_len = htons(ntohs(iph->tot_len) - len);
if (skb->len < iphlen + len) {
/* packet is too small!?! */
return 0;
}

/* pull the data buffer up to the ESP header and set the
* transport header to point to ESP. Keep UDP on the stack
* for later.
*/
__skb_pull(skb, len);
skb_reset_transport_header(skb);

/* modify the protocol (it's ESP!) */
iph->protocol = IPPROTO_ESP;

/* and let the caller know to send this into the ESP processor... */
return -1;
#endif
}

/* returns:
* -1: error
* 0: success
Expand All @@ -1044,44 +942,36 @@ int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)

if (up->encap_type) {
/*
* This is an encapsulation socket, so let's see if this is
* an encapsulated packet.
* If it's a keepalive packet, then just eat it.
* If it's an encapsulateed packet, then pass it to the
* IPsec xfrm input and return the response
* appropriately. Otherwise, just fall through and
* pass this up the UDP socket.
* This is an encapsulation socket so pass the skb to
* the socket's udp_encap_rcv() hook. Otherwise, just
* fall through and pass this up the UDP socket.
* up->encap_rcv() returns the following value:
* =0 if skb was successfully passed to the encap
* handler or was discarded by it.
* >0 if skb should be passed on to UDP.
* <0 if skb should be resubmitted as proto -N
*/
int ret;
unsigned int len;

ret = udp_encap_rcv(sk, skb);
if (ret == 0) {
/* Eat the packet .. */
kfree_skb(skb);
return 0;
}
if (ret == -1) {
/* process the ESP packet */
ret = xfrm4_rcv_encap(skb, up->encap_type);
UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS, up->pcflag);
return -ret;
}
if (ret == -2) {
/* process the L2TP packet */
if (up->encap_rcv != NULL) {
ret = (*up->encap_rcv)(sk, skb);
if (ret <= 0) {
UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS, up->pcflag);
return ret;
}

/* FALLTHROUGH -- pass up as UDP packet */
/* if we're overly short, let UDP handle it */
len = skb->len - sizeof(struct udphdr);
if (len <= 0)
goto udp;

if (up->encap_rcv != NULL) {
int ret;

ret = (*up->encap_rcv)(sk, skb);
if (ret <= 0) {
UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS, up->pcflag);
return -ret;
}
}

/* FALLTHROUGH -- it's a UDP Packet */
}

udp:
/*
* UDP-Lite specific tests, ignored on UDP sockets
*/
Expand Down Expand Up @@ -1367,6 +1257,8 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname,
case 0:
case UDP_ENCAP_ESPINUDP:
case UDP_ENCAP_ESPINUDP_NON_IKE:
up->encap_rcv = xfrm4_udp_encap_rcv;
/* FALLTHROUGH */
case UDP_ENCAP_L2TPINUDP:
up->encap_type = val;
break;
Expand Down
114 changes: 106 additions & 8 deletions net/ipv4/xfrm4_input.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -16,13 +16,6 @@
#include <net/ip.h>
#include <net/xfrm.h>

int xfrm4_rcv(struct sk_buff *skb)
{
return xfrm4_rcv_encap(skb, 0);
}

EXPORT_SYMBOL(xfrm4_rcv);

static int xfrm4_parse_spi(struct sk_buff *skb, u8 nexthdr, __be32 *spi, __be32 *seq)
{
switch (nexthdr) {
Expand Down Expand Up @@ -53,7 +46,7 @@ static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
}
#endif

int xfrm4_rcv_encap(struct sk_buff *skb, __u16 encap_type)
static int xfrm4_rcv_encap(struct sk_buff *skb, __u16 encap_type)
{
__be32 spi, seq;
struct xfrm_state *xfrm_vec[XFRM_MAX_DEPTH];
Expand Down Expand Up @@ -167,3 +160,108 @@ int xfrm4_rcv_encap(struct sk_buff *skb, __u16 encap_type)
kfree_skb(skb);
return 0;
}

/* If it's a keepalive packet, then just eat it.
* If it's an encapsulated packet, then pass it to the
* IPsec xfrm input.
* Returns 0 if skb passed to xfrm or was dropped.
* Returns >0 if skb should be passed to UDP.
* Returns <0 if skb should be resubmitted (-ret is protocol)
*/
int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
{
struct udp_sock *up = udp_sk(sk);
struct udphdr *uh;
struct iphdr *iph;
int iphlen, len;
int ret;

__u8 *udpdata;
__be32 *udpdata32;
__u16 encap_type = up->encap_type;

/* if this is not encapsulated socket, then just return now */
if (!encap_type)
return 1;

/* If this is a paged skb, make sure we pull up
* whatever data we need to look at. */
len = skb->len - sizeof(struct udphdr);
if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
return 1;

/* Now we can get the pointers */
uh = udp_hdr(skb);
udpdata = (__u8 *)uh + sizeof(struct udphdr);
udpdata32 = (__be32 *)udpdata;

switch (encap_type) {
default:
case UDP_ENCAP_ESPINUDP:
/* Check if this is a keepalive packet. If so, eat it. */
if (len == 1 && udpdata[0] == 0xff) {
goto drop;
} else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
/* ESP Packet without Non-ESP header */
len = sizeof(struct udphdr);
} else
/* Must be an IKE packet.. pass it through */
return 1;
break;
case UDP_ENCAP_ESPINUDP_NON_IKE:
/* Check if this is a keepalive packet. If so, eat it. */
if (len == 1 && udpdata[0] == 0xff) {
goto drop;
} else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
udpdata32[0] == 0 && udpdata32[1] == 0) {

/* ESP Packet with Non-IKE marker */
len = sizeof(struct udphdr) + 2 * sizeof(u32);
} else
/* Must be an IKE packet.. pass it through */
return 1;
break;
}

/* At this point we are sure that this is an ESPinUDP packet,
* so we need to remove 'len' bytes from the packet (the UDP
* header and optional ESP marker bytes) and then modify the
* protocol to ESP, and then call into the transform receiver.
*/
if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
goto drop;

/* Now we can update and verify the packet length... */
iph = ip_hdr(skb);
iphlen = iph->ihl << 2;
iph->tot_len = htons(ntohs(iph->tot_len) - len);
if (skb->len < iphlen + len) {
/* packet is too small!?! */
goto drop;
}

/* pull the data buffer up to the ESP header and set the
* transport header to point to ESP. Keep UDP on the stack
* for later.
*/
__skb_pull(skb, len);
skb_reset_transport_header(skb);

/* modify the protocol (it's ESP!) */
iph->protocol = IPPROTO_ESP;

/* process ESP */
ret = xfrm4_rcv_encap(skb, encap_type);
return ret;

drop:
kfree_skb(skb);
return 0;
}

int xfrm4_rcv(struct sk_buff *skb)
{
return xfrm4_rcv_encap(skb, 0);
}

EXPORT_SYMBOL(xfrm4_rcv);

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