1 /* 2 * xfrm4_output.c - Common IPsec encapsulation code for IPv4. 3 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au> 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 11 #include <linux/compiler.h> 12 #include <linux/if_ether.h> 13 #include <linux/kernel.h> 14 #include <linux/skbuff.h> 15 #include <linux/netfilter_ipv4.h> 16 #include <net/ip.h> 17 #include <net/xfrm.h> 18 #include <net/icmp.h> 19 20 static int xfrm4_tunnel_check_size(struct sk_buff *skb) 21 { 22 int mtu, ret = 0; 23 struct dst_entry *dst; 24 25 if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE) 26 goto out; 27 28 IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE; 29 30 if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df) 31 goto out; 32 33 dst = skb->dst; 34 mtu = dst_mtu(dst); 35 if (skb->len > mtu) { 36 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); 37 ret = -EMSGSIZE; 38 } 39 out: 40 return ret; 41 } 42 43 static inline int xfrm4_output_one(struct sk_buff *skb) 44 { 45 struct dst_entry *dst = skb->dst; 46 struct xfrm_state *x = dst->xfrm; 47 struct iphdr *iph; 48 int err; 49 50 if (x->props.mode == XFRM_MODE_TUNNEL) { 51 err = xfrm4_tunnel_check_size(skb); 52 if (err) 53 goto error_nolock; 54 } 55 56 err = xfrm_output(skb); 57 if (err) 58 goto error_nolock; 59 60 iph = ip_hdr(skb); 61 iph->tot_len = htons(skb->len); 62 ip_send_check(iph); 63 64 IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED; 65 err = 0; 66 67 out_exit: 68 return err; 69 error_nolock: 70 kfree_skb(skb); 71 goto out_exit; 72 } 73 74 static int xfrm4_output_finish2(struct sk_buff *skb) 75 { 76 int err; 77 78 while (likely((err = xfrm4_output_one(skb)) == 0)) { 79 nf_reset(skb); 80 81 err = nf_hook(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, 82 skb->dst->dev, dst_output); 83 if (unlikely(err != 1)) 84 break; 85 86 if (!skb->dst->xfrm) 87 return dst_output(skb); 88 89 err = nf_hook(PF_INET, NF_IP_POST_ROUTING, skb, NULL, 90 skb->dst->dev, xfrm4_output_finish2); 91 if (unlikely(err != 1)) 92 break; 93 } 94 95 return err; 96 } 97 98 static int xfrm4_output_finish(struct sk_buff *skb) 99 { 100 struct sk_buff *segs; 101 102 #ifdef CONFIG_NETFILTER 103 if (!skb->dst->xfrm) { 104 IPCB(skb)->flags |= IPSKB_REROUTED; 105 return dst_output(skb); 106 } 107 #endif 108 109 if (!skb_is_gso(skb)) 110 return xfrm4_output_finish2(skb); 111 112 skb->protocol = htons(ETH_P_IP); 113 segs = skb_gso_segment(skb, 0); 114 kfree_skb(skb); 115 if (unlikely(IS_ERR(segs))) 116 return PTR_ERR(segs); 117 118 do { 119 struct sk_buff *nskb = segs->next; 120 int err; 121 122 segs->next = NULL; 123 err = xfrm4_output_finish2(segs); 124 125 if (unlikely(err)) { 126 while ((segs = nskb)) { 127 nskb = segs->next; 128 segs->next = NULL; 129 kfree_skb(segs); 130 } 131 return err; 132 } 133 134 segs = nskb; 135 } while (segs); 136 137 return 0; 138 } 139 140 int xfrm4_output(struct sk_buff *skb) 141 { 142 return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dst->dev, 143 xfrm4_output_finish, 144 !(IPCB(skb)->flags & IPSKB_REROUTED)); 145 } 146