xref: /openbmc/linux/net/ipv6/udp_offload.c (revision 6774def6)
1 /*
2  *	IPV6 GSO/GRO offload support
3  *	Linux INET6 implementation
4  *
5  *	This program is free software; you can redistribute it and/or
6  *      modify it under the terms of the GNU General Public License
7  *      as published by the Free Software Foundation; either version
8  *      2 of the License, or (at your option) any later version.
9  *
10  *      UDPv6 GSO support
11  */
12 #include <linux/skbuff.h>
13 #include <linux/netdevice.h>
14 #include <net/protocol.h>
15 #include <net/ipv6.h>
16 #include <net/udp.h>
17 #include <net/ip6_checksum.h>
18 #include "ip6_offload.h"
19 
20 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
21 					 netdev_features_t features)
22 {
23 	struct sk_buff *segs = ERR_PTR(-EINVAL);
24 	unsigned int mss;
25 	unsigned int unfrag_ip6hlen, unfrag_len;
26 	struct frag_hdr *fptr;
27 	u8 *packet_start, *prevhdr;
28 	u8 nexthdr;
29 	u8 frag_hdr_sz = sizeof(struct frag_hdr);
30 	__wsum csum;
31 	int tnl_hlen;
32 
33 	mss = skb_shinfo(skb)->gso_size;
34 	if (unlikely(skb->len <= mss))
35 		goto out;
36 
37 	if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
38 		/* Packet is from an untrusted source, reset gso_segs. */
39 		int type = skb_shinfo(skb)->gso_type;
40 
41 		if (unlikely(type & ~(SKB_GSO_UDP |
42 				      SKB_GSO_DODGY |
43 				      SKB_GSO_UDP_TUNNEL |
44 				      SKB_GSO_UDP_TUNNEL_CSUM |
45 				      SKB_GSO_GRE |
46 				      SKB_GSO_GRE_CSUM |
47 				      SKB_GSO_IPIP |
48 				      SKB_GSO_SIT |
49 				      SKB_GSO_MPLS) ||
50 			     !(type & (SKB_GSO_UDP))))
51 			goto out;
52 
53 		skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
54 
55 		segs = NULL;
56 		goto out;
57 	}
58 
59 	if (skb->encapsulation && skb_shinfo(skb)->gso_type &
60 	    (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
61 		segs = skb_udp_tunnel_segment(skb, features, true);
62 	else {
63 		const struct ipv6hdr *ipv6h;
64 		struct udphdr *uh;
65 
66 		if (!pskb_may_pull(skb, sizeof(struct udphdr)))
67 			goto out;
68 
69 		/* Do software UFO. Complete and fill in the UDP checksum as HW cannot
70 		 * do checksum of UDP packets sent as multiple IP fragments.
71 		 */
72 
73 		uh = udp_hdr(skb);
74 		ipv6h = ipv6_hdr(skb);
75 
76 		uh->check = 0;
77 		csum = skb_checksum(skb, 0, skb->len, 0);
78 		uh->check = udp_v6_check(skb->len, &ipv6h->saddr,
79 					  &ipv6h->daddr, csum);
80 
81 		if (uh->check == 0)
82 			uh->check = CSUM_MANGLED_0;
83 
84 		skb->ip_summed = CHECKSUM_NONE;
85 
86 		/* Check if there is enough headroom to insert fragment header. */
87 		tnl_hlen = skb_tnl_header_len(skb);
88 		if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
89 			if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
90 				goto out;
91 		}
92 
93 		/* Find the unfragmentable header and shift it left by frag_hdr_sz
94 		 * bytes to insert fragment header.
95 		 */
96 		unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
97 		nexthdr = *prevhdr;
98 		*prevhdr = NEXTHDR_FRAGMENT;
99 		unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
100 			     unfrag_ip6hlen + tnl_hlen;
101 		packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
102 		memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
103 
104 		SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
105 		skb->mac_header -= frag_hdr_sz;
106 		skb->network_header -= frag_hdr_sz;
107 
108 		fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
109 		fptr->nexthdr = nexthdr;
110 		fptr->reserved = 0;
111 		fptr->identification = skb_shinfo(skb)->ip6_frag_id;
112 
113 		/* Fragment the skb. ipv6 header and the remaining fields of the
114 		 * fragment header are updated in ipv6_gso_segment()
115 		 */
116 		segs = skb_segment(skb, features);
117 	}
118 
119 out:
120 	return segs;
121 }
122 
123 static struct sk_buff **udp6_gro_receive(struct sk_buff **head,
124 					 struct sk_buff *skb)
125 {
126 	struct udphdr *uh = udp_gro_udphdr(skb);
127 
128 	if (unlikely(!uh))
129 		goto flush;
130 
131 	/* Don't bother verifying checksum if we're going to flush anyway. */
132 	if (NAPI_GRO_CB(skb)->flush)
133 		goto skip;
134 
135 	if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
136 						 ip6_gro_compute_pseudo))
137 		goto flush;
138 	else if (uh->check)
139 		skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
140 					     ip6_gro_compute_pseudo);
141 
142 skip:
143 	NAPI_GRO_CB(skb)->is_ipv6 = 1;
144 	return udp_gro_receive(head, skb, uh);
145 
146 flush:
147 	NAPI_GRO_CB(skb)->flush = 1;
148 	return NULL;
149 }
150 
151 static int udp6_gro_complete(struct sk_buff *skb, int nhoff)
152 {
153 	const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
154 	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
155 
156 	if (uh->check)
157 		uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
158 					  &ipv6h->daddr, 0);
159 
160 	return udp_gro_complete(skb, nhoff);
161 }
162 
163 static const struct net_offload udpv6_offload = {
164 	.callbacks = {
165 		.gso_segment	=	udp6_ufo_fragment,
166 		.gro_receive	=	udp6_gro_receive,
167 		.gro_complete	=	udp6_gro_complete,
168 	},
169 };
170 
171 int __init udp_offload_init(void)
172 {
173 	return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
174 }
175