1 #include <linux/errno.h>
2 #include <linux/ip.h>
3 #include <linux/kernel.h>
4 #include <linux/module.h>
5 #include <linux/skbuff.h>
6 #include <linux/socket.h>
7 #include <linux/types.h>
8 #include <net/checksum.h>
9 #include <net/ip.h>
10 #include <net/ip6_fib.h>
11 #include <net/lwtunnel.h>
12 #include <net/protocol.h>
13 #include <uapi/linux/ila.h>
14 #include "ila.h"
15 
ila_init_saved_csum(struct ila_params * p)16 void ila_init_saved_csum(struct ila_params *p)
17 {
18 	if (!p->locator_match.v64)
19 		return;
20 
21 	p->csum_diff = compute_csum_diff8(
22 				(__be32 *)&p->locator,
23 				(__be32 *)&p->locator_match);
24 }
25 
get_csum_diff_iaddr(struct ila_addr * iaddr,struct ila_params * p)26 static __wsum get_csum_diff_iaddr(struct ila_addr *iaddr, struct ila_params *p)
27 {
28 	if (p->locator_match.v64)
29 		return p->csum_diff;
30 	else
31 		return compute_csum_diff8((__be32 *)&p->locator,
32 					  (__be32 *)&iaddr->loc);
33 }
34 
get_csum_diff(struct ipv6hdr * ip6h,struct ila_params * p)35 static __wsum get_csum_diff(struct ipv6hdr *ip6h, struct ila_params *p)
36 {
37 	return get_csum_diff_iaddr(ila_a2i(&ip6h->daddr), p);
38 }
39 
ila_csum_do_neutral_fmt(struct ila_addr * iaddr,struct ila_params * p)40 static void ila_csum_do_neutral_fmt(struct ila_addr *iaddr,
41 				    struct ila_params *p)
42 {
43 	__sum16 *adjust = (__force __sum16 *)&iaddr->ident.v16[3];
44 	__wsum diff, fval;
45 
46 	diff = get_csum_diff_iaddr(iaddr, p);
47 
48 	fval = (__force __wsum)(ila_csum_neutral_set(iaddr->ident) ?
49 			CSUM_NEUTRAL_FLAG : ~CSUM_NEUTRAL_FLAG);
50 
51 	diff = csum_add(diff, fval);
52 
53 	*adjust = ~csum_fold(csum_add(diff, csum_unfold(*adjust)));
54 
55 	/* Flip the csum-neutral bit. Either we are doing a SIR->ILA
56 	 * translation with ILA_CSUM_NEUTRAL_MAP as the csum_method
57 	 * and the C-bit is not set, or we are doing an ILA-SIR
58 	 * tranlsation and the C-bit is set.
59 	 */
60 	iaddr->ident.csum_neutral ^= 1;
61 }
62 
ila_csum_do_neutral_nofmt(struct ila_addr * iaddr,struct ila_params * p)63 static void ila_csum_do_neutral_nofmt(struct ila_addr *iaddr,
64 				      struct ila_params *p)
65 {
66 	__sum16 *adjust = (__force __sum16 *)&iaddr->ident.v16[3];
67 	__wsum diff;
68 
69 	diff = get_csum_diff_iaddr(iaddr, p);
70 
71 	*adjust = ~csum_fold(csum_add(diff, csum_unfold(*adjust)));
72 }
73 
ila_csum_adjust_transport(struct sk_buff * skb,struct ila_params * p)74 static void ila_csum_adjust_transport(struct sk_buff *skb,
75 				      struct ila_params *p)
76 {
77 	size_t nhoff = sizeof(struct ipv6hdr);
78 	struct ipv6hdr *ip6h = ipv6_hdr(skb);
79 	__wsum diff;
80 
81 	switch (ip6h->nexthdr) {
82 	case NEXTHDR_TCP:
83 		if (likely(pskb_may_pull(skb, nhoff + sizeof(struct tcphdr)))) {
84 			struct tcphdr *th = (struct tcphdr *)
85 					(skb_network_header(skb) + nhoff);
86 
87 			diff = get_csum_diff(ip6h, p);
88 			inet_proto_csum_replace_by_diff(&th->check, skb,
89 							diff, true);
90 		}
91 		break;
92 	case NEXTHDR_UDP:
93 		if (likely(pskb_may_pull(skb, nhoff + sizeof(struct udphdr)))) {
94 			struct udphdr *uh = (struct udphdr *)
95 					(skb_network_header(skb) + nhoff);
96 
97 			if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) {
98 				diff = get_csum_diff(ip6h, p);
99 				inet_proto_csum_replace_by_diff(&uh->check, skb,
100 								diff, true);
101 				if (!uh->check)
102 					uh->check = CSUM_MANGLED_0;
103 			}
104 		}
105 		break;
106 	case NEXTHDR_ICMP:
107 		if (likely(pskb_may_pull(skb,
108 					 nhoff + sizeof(struct icmp6hdr)))) {
109 			struct icmp6hdr *ih = (struct icmp6hdr *)
110 					(skb_network_header(skb) + nhoff);
111 
112 			diff = get_csum_diff(ip6h, p);
113 			inet_proto_csum_replace_by_diff(&ih->icmp6_cksum, skb,
114 							diff, true);
115 		}
116 		break;
117 	}
118 }
119 
ila_update_ipv6_locator(struct sk_buff * skb,struct ila_params * p,bool sir2ila)120 void ila_update_ipv6_locator(struct sk_buff *skb, struct ila_params *p,
121 			     bool sir2ila)
122 {
123 	struct ipv6hdr *ip6h = ipv6_hdr(skb);
124 	struct ila_addr *iaddr = ila_a2i(&ip6h->daddr);
125 
126 	switch (p->csum_mode) {
127 	case ILA_CSUM_ADJUST_TRANSPORT:
128 		ila_csum_adjust_transport(skb, p);
129 		break;
130 	case ILA_CSUM_NEUTRAL_MAP:
131 		if (sir2ila) {
132 			if (WARN_ON(ila_csum_neutral_set(iaddr->ident))) {
133 				/* Checksum flag should never be
134 				 * set in a formatted SIR address.
135 				 */
136 				break;
137 			}
138 		} else if (!ila_csum_neutral_set(iaddr->ident)) {
139 			/* ILA to SIR translation and C-bit isn't
140 			 * set so we're good.
141 			 */
142 			break;
143 		}
144 		ila_csum_do_neutral_fmt(iaddr, p);
145 		break;
146 	case ILA_CSUM_NEUTRAL_MAP_AUTO:
147 		ila_csum_do_neutral_nofmt(iaddr, p);
148 		break;
149 	case ILA_CSUM_NO_ACTION:
150 		break;
151 	}
152 
153 	/* Now change destination address */
154 	iaddr->loc = p->locator;
155 }
156