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 int err; 48 49 if (x->props.mode == XFRM_MODE_TUNNEL) { 50 err = xfrm4_tunnel_check_size(skb); 51 if (err) 52 goto error_nolock; 53 } 54 55 err = xfrm_output(skb); 56 if (err) 57 goto error_nolock; 58 59 IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED; 60 err = 0; 61 62 out_exit: 63 return err; 64 error_nolock: 65 kfree_skb(skb); 66 goto out_exit; 67 } 68 69 static int xfrm4_output_finish2(struct sk_buff *skb) 70 { 71 int err; 72 73 while (likely((err = xfrm4_output_one(skb)) == 0)) { 74 nf_reset(skb); 75 76 err = nf_hook(PF_INET, NF_IP_LOCAL_OUT, &skb, NULL, 77 skb->dst->dev, dst_output); 78 if (unlikely(err != 1)) 79 break; 80 81 if (!skb->dst->xfrm) 82 return dst_output(skb); 83 84 err = nf_hook(PF_INET, NF_IP_POST_ROUTING, &skb, NULL, 85 skb->dst->dev, xfrm4_output_finish2); 86 if (unlikely(err != 1)) 87 break; 88 } 89 90 return err; 91 } 92 93 static int xfrm4_output_finish(struct sk_buff *skb) 94 { 95 struct sk_buff *segs; 96 97 #ifdef CONFIG_NETFILTER 98 if (!skb->dst->xfrm) { 99 IPCB(skb)->flags |= IPSKB_REROUTED; 100 return dst_output(skb); 101 } 102 #endif 103 104 if (!skb_is_gso(skb)) 105 return xfrm4_output_finish2(skb); 106 107 skb->protocol = htons(ETH_P_IP); 108 segs = skb_gso_segment(skb, 0); 109 kfree_skb(skb); 110 if (unlikely(IS_ERR(segs))) 111 return PTR_ERR(segs); 112 113 do { 114 struct sk_buff *nskb = segs->next; 115 int err; 116 117 segs->next = NULL; 118 err = xfrm4_output_finish2(segs); 119 120 if (unlikely(err)) { 121 while ((segs = nskb)) { 122 nskb = segs->next; 123 segs->next = NULL; 124 kfree_skb(segs); 125 } 126 return err; 127 } 128 129 segs = nskb; 130 } while (segs); 131 132 return 0; 133 } 134 135 int xfrm4_output(struct sk_buff *skb) 136 { 137 return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dst->dev, 138 xfrm4_output_finish, 139 !(IPCB(skb)->flags & IPSKB_REROUTED)); 140 } 141