1 /* 2 * xfrm4_input.c 3 * 4 * Changes: 5 * YOSHIFUJI Hideaki @USAGI 6 * Split up af-specific portion 7 * Derek Atkins <derek@ihtfp.com> 8 * Add Encapsulation support 9 * 10 */ 11 12 #include <linux/module.h> 13 #include <linux/string.h> 14 #include <linux/netfilter.h> 15 #include <linux/netfilter_ipv4.h> 16 #include <net/inet_ecn.h> 17 #include <net/ip.h> 18 #include <net/xfrm.h> 19 20 int xfrm4_rcv(struct sk_buff *skb) 21 { 22 return xfrm4_rcv_encap(skb, 0); 23 } 24 25 EXPORT_SYMBOL(xfrm4_rcv); 26 27 static inline void ipip_ecn_decapsulate(struct sk_buff *skb) 28 { 29 struct iphdr *outer_iph = skb->nh.iph; 30 struct iphdr *inner_iph = skb->h.ipiph; 31 32 if (INET_ECN_is_ce(outer_iph->tos)) 33 IP_ECN_set_ce(inner_iph); 34 } 35 36 static int xfrm4_parse_spi(struct sk_buff *skb, u8 nexthdr, u32 *spi, u32 *seq) 37 { 38 switch (nexthdr) { 39 case IPPROTO_IPIP: 40 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 41 return -EINVAL; 42 *spi = skb->nh.iph->saddr; 43 *seq = 0; 44 return 0; 45 } 46 47 return xfrm_parse_spi(skb, nexthdr, spi, seq); 48 } 49 50 #ifdef CONFIG_NETFILTER 51 static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb) 52 { 53 struct iphdr *iph = skb->nh.iph; 54 55 if (skb->dst == NULL) { 56 if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, 57 skb->dev)) 58 goto drop; 59 } 60 return dst_input(skb); 61 drop: 62 kfree_skb(skb); 63 return NET_RX_DROP; 64 } 65 #endif 66 67 int xfrm4_rcv_encap(struct sk_buff *skb, __u16 encap_type) 68 { 69 int err; 70 u32 spi, seq; 71 struct sec_decap_state xfrm_vec[XFRM_MAX_DEPTH]; 72 struct xfrm_state *x; 73 int xfrm_nr = 0; 74 int decaps = 0; 75 76 if ((err = xfrm4_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) != 0) 77 goto drop; 78 79 do { 80 struct iphdr *iph = skb->nh.iph; 81 82 if (xfrm_nr == XFRM_MAX_DEPTH) 83 goto drop; 84 85 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, iph->protocol, AF_INET); 86 if (x == NULL) 87 goto drop; 88 89 spin_lock(&x->lock); 90 if (unlikely(x->km.state != XFRM_STATE_VALID)) 91 goto drop_unlock; 92 93 if (x->props.replay_window && xfrm_replay_check(x, seq)) 94 goto drop_unlock; 95 96 if (xfrm_state_check_expire(x)) 97 goto drop_unlock; 98 99 xfrm_vec[xfrm_nr].decap.decap_type = encap_type; 100 if (x->type->input(x, &(xfrm_vec[xfrm_nr].decap), skb)) 101 goto drop_unlock; 102 103 /* only the first xfrm gets the encap type */ 104 encap_type = 0; 105 106 if (x->props.replay_window) 107 xfrm_replay_advance(x, seq); 108 109 x->curlft.bytes += skb->len; 110 x->curlft.packets++; 111 112 spin_unlock(&x->lock); 113 114 xfrm_vec[xfrm_nr++].xvec = x; 115 116 iph = skb->nh.iph; 117 118 if (x->props.mode) { 119 if (iph->protocol != IPPROTO_IPIP) 120 goto drop; 121 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 122 goto drop; 123 if (skb_cloned(skb) && 124 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 125 goto drop; 126 if (x->props.flags & XFRM_STATE_DECAP_DSCP) 127 ipv4_copy_dscp(iph, skb->h.ipiph); 128 if (!(x->props.flags & XFRM_STATE_NOECN)) 129 ipip_ecn_decapsulate(skb); 130 skb->mac.raw = memmove(skb->data - skb->mac_len, 131 skb->mac.raw, skb->mac_len); 132 skb->nh.raw = skb->data; 133 memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options)); 134 decaps = 1; 135 break; 136 } 137 138 if ((err = xfrm_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) < 0) 139 goto drop; 140 } while (!err); 141 142 /* Allocate new secpath or COW existing one. */ 143 144 if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) { 145 struct sec_path *sp; 146 sp = secpath_dup(skb->sp); 147 if (!sp) 148 goto drop; 149 if (skb->sp) 150 secpath_put(skb->sp); 151 skb->sp = sp; 152 } 153 if (xfrm_nr + skb->sp->len > XFRM_MAX_DEPTH) 154 goto drop; 155 156 memcpy(skb->sp->x+skb->sp->len, xfrm_vec, xfrm_nr*sizeof(struct sec_decap_state)); 157 skb->sp->len += xfrm_nr; 158 159 nf_reset(skb); 160 161 if (decaps) { 162 if (!(skb->dev->flags&IFF_LOOPBACK)) { 163 dst_release(skb->dst); 164 skb->dst = NULL; 165 } 166 netif_rx(skb); 167 return 0; 168 } else { 169 #ifdef CONFIG_NETFILTER 170 __skb_push(skb, skb->data - skb->nh.raw); 171 skb->nh.iph->tot_len = htons(skb->len); 172 ip_send_check(skb->nh.iph); 173 174 NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL, 175 xfrm4_rcv_encap_finish); 176 return 0; 177 #else 178 return -skb->nh.iph->protocol; 179 #endif 180 } 181 182 drop_unlock: 183 spin_unlock(&x->lock); 184 xfrm_state_put(x); 185 drop: 186 while (--xfrm_nr >= 0) 187 xfrm_state_put(xfrm_vec[xfrm_nr].xvec); 188 189 kfree_skb(skb); 190 return 0; 191 } 192