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/if_ether.h> 12 #include <linux/kernel.h> 13 #include <linux/module.h> 14 #include <linux/skbuff.h> 15 #include <linux/netfilter_ipv4.h> 16 #include <net/dst.h> 17 #include <net/ip.h> 18 #include <net/xfrm.h> 19 #include <net/icmp.h> 20 21 static int xfrm4_tunnel_check_size(struct sk_buff *skb) 22 { 23 int mtu, ret = 0; 24 struct dst_entry *dst; 25 26 if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE) 27 goto out; 28 29 if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df) 30 goto out; 31 32 dst = skb->dst; 33 mtu = dst_mtu(dst); 34 if (skb->len > mtu) { 35 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); 36 ret = -EMSGSIZE; 37 } 38 out: 39 return ret; 40 } 41 42 int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb) 43 { 44 int err; 45 46 err = xfrm4_tunnel_check_size(skb); 47 if (err) 48 return err; 49 50 return xfrm4_extract_header(skb); 51 } 52 53 int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb) 54 { 55 int err; 56 57 err = x->inner_mode->afinfo->extract_output(x, skb); 58 if (err) 59 return err; 60 61 memset(IPCB(skb), 0, sizeof(*IPCB(skb))); 62 IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE; 63 64 skb->protocol = htons(ETH_P_IP); 65 66 return x->outer_mode->output2(x, skb); 67 } 68 EXPORT_SYMBOL(xfrm4_prepare_output); 69 70 static inline int xfrm4_output_one(struct sk_buff *skb) 71 { 72 int err; 73 74 err = xfrm_output(skb); 75 if (err) 76 goto error_nolock; 77 78 IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED; 79 err = 0; 80 81 out_exit: 82 return err; 83 error_nolock: 84 kfree_skb(skb); 85 goto out_exit; 86 } 87 88 static int xfrm4_output_finish2(struct sk_buff *skb) 89 { 90 int err; 91 92 while (likely((err = xfrm4_output_one(skb)) == 0)) { 93 nf_reset(skb); 94 95 err = __ip_local_out(skb); 96 if (unlikely(err != 1)) 97 break; 98 99 if (!skb->dst->xfrm) 100 return dst_output(skb); 101 102 err = nf_hook(PF_INET, NF_IP_POST_ROUTING, skb, NULL, 103 skb->dst->dev, xfrm4_output_finish2); 104 if (unlikely(err != 1)) 105 break; 106 } 107 108 return err; 109 } 110 111 static int xfrm4_output_finish(struct sk_buff *skb) 112 { 113 struct sk_buff *segs; 114 115 #ifdef CONFIG_NETFILTER 116 if (!skb->dst->xfrm) { 117 IPCB(skb)->flags |= IPSKB_REROUTED; 118 return dst_output(skb); 119 } 120 #endif 121 122 if (!skb_is_gso(skb)) 123 return xfrm4_output_finish2(skb); 124 125 skb->protocol = htons(ETH_P_IP); 126 segs = skb_gso_segment(skb, 0); 127 kfree_skb(skb); 128 if (unlikely(IS_ERR(segs))) 129 return PTR_ERR(segs); 130 131 do { 132 struct sk_buff *nskb = segs->next; 133 int err; 134 135 segs->next = NULL; 136 err = xfrm4_output_finish2(segs); 137 138 if (unlikely(err)) { 139 while ((segs = nskb)) { 140 nskb = segs->next; 141 segs->next = NULL; 142 kfree_skb(segs); 143 } 144 return err; 145 } 146 147 segs = nskb; 148 } while (segs); 149 150 return 0; 151 } 152 153 int xfrm4_output(struct sk_buff *skb) 154 { 155 return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dst->dev, 156 xfrm4_output_finish, 157 !(IPCB(skb)->flags & IPSKB_REROUTED)); 158 } 159