1 /* 2 * xfrm_output.c - Common IPsec encapsulation code. 3 * 4 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 12 #include <linux/errno.h> 13 #include <linux/module.h> 14 #include <linux/netdevice.h> 15 #include <linux/netfilter.h> 16 #include <linux/skbuff.h> 17 #include <linux/slab.h> 18 #include <linux/spinlock.h> 19 #include <net/dst.h> 20 #include <net/xfrm.h> 21 22 static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb); 23 24 static int xfrm_skb_check_space(struct sk_buff *skb) 25 { 26 struct dst_entry *dst = skb_dst(skb); 27 int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev) 28 - skb_headroom(skb); 29 int ntail = dst->dev->needed_tailroom - skb_tailroom(skb); 30 31 if (nhead <= 0) { 32 if (ntail <= 0) 33 return 0; 34 nhead = 0; 35 } else if (ntail < 0) 36 ntail = 0; 37 38 return pskb_expand_head(skb, nhead, ntail, GFP_ATOMIC); 39 } 40 41 /* Children define the path of the packet through the 42 * Linux networking. Thus, destinations are stackable. 43 */ 44 45 static struct dst_entry *skb_dst_pop(struct sk_buff *skb) 46 { 47 struct dst_entry *child = dst_clone(skb_dst(skb)->child); 48 49 skb_dst_drop(skb); 50 return child; 51 } 52 53 static int xfrm_output_one(struct sk_buff *skb, int err) 54 { 55 struct dst_entry *dst = skb_dst(skb); 56 struct xfrm_state *x = dst->xfrm; 57 struct net *net = xs_net(x); 58 59 if (err <= 0) 60 goto resume; 61 62 do { 63 err = xfrm_skb_check_space(skb); 64 if (err) { 65 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR); 66 goto error_nolock; 67 } 68 69 err = x->outer_mode->output(x, skb); 70 if (err) { 71 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR); 72 goto error_nolock; 73 } 74 75 spin_lock_bh(&x->lock); 76 77 if (unlikely(x->km.state != XFRM_STATE_VALID)) { 78 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID); 79 err = -EINVAL; 80 goto error; 81 } 82 83 err = xfrm_state_check_expire(x); 84 if (err) { 85 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED); 86 goto error; 87 } 88 89 err = x->repl->overflow(x, skb); 90 if (err) { 91 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR); 92 goto error; 93 } 94 95 x->curlft.bytes += skb->len; 96 x->curlft.packets++; 97 98 spin_unlock_bh(&x->lock); 99 100 skb_dst_force(skb); 101 102 /* Inner headers are invalid now. */ 103 skb->encapsulation = 0; 104 105 err = x->type->output(x, skb); 106 if (err == -EINPROGRESS) 107 goto out; 108 109 resume: 110 if (err) { 111 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR); 112 goto error_nolock; 113 } 114 115 dst = skb_dst_pop(skb); 116 if (!dst) { 117 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR); 118 err = -EHOSTUNREACH; 119 goto error_nolock; 120 } 121 skb_dst_set(skb, dst); 122 x = dst->xfrm; 123 } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL)); 124 125 return 0; 126 127 error: 128 spin_unlock_bh(&x->lock); 129 error_nolock: 130 kfree_skb(skb); 131 out: 132 return err; 133 } 134 135 int xfrm_output_resume(struct sk_buff *skb, int err) 136 { 137 struct net *net = xs_net(skb_dst(skb)->xfrm); 138 139 while (likely((err = xfrm_output_one(skb, err)) == 0)) { 140 nf_reset(skb); 141 142 err = skb_dst(skb)->ops->local_out(net, skb->sk, skb); 143 if (unlikely(err != 1)) 144 goto out; 145 146 if (!skb_dst(skb)->xfrm) 147 return dst_output(net, skb->sk, skb); 148 149 err = nf_hook(skb_dst(skb)->ops->family, 150 NF_INET_POST_ROUTING, net, skb->sk, skb, 151 NULL, skb_dst(skb)->dev, xfrm_output2); 152 if (unlikely(err != 1)) 153 goto out; 154 } 155 156 if (err == -EINPROGRESS) 157 err = 0; 158 159 out: 160 return err; 161 } 162 EXPORT_SYMBOL_GPL(xfrm_output_resume); 163 164 static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb) 165 { 166 return xfrm_output_resume(skb, 1); 167 } 168 169 static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb) 170 { 171 struct sk_buff *segs; 172 173 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET); 174 BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_SGO_CB_OFFSET); 175 segs = skb_gso_segment(skb, 0); 176 kfree_skb(skb); 177 if (IS_ERR(segs)) 178 return PTR_ERR(segs); 179 if (segs == NULL) 180 return -EINVAL; 181 182 do { 183 struct sk_buff *nskb = segs->next; 184 int err; 185 186 segs->next = NULL; 187 err = xfrm_output2(net, sk, segs); 188 189 if (unlikely(err)) { 190 kfree_skb_list(nskb); 191 return err; 192 } 193 194 segs = nskb; 195 } while (segs); 196 197 return 0; 198 } 199 200 int xfrm_output(struct sock *sk, struct sk_buff *skb) 201 { 202 struct net *net = dev_net(skb_dst(skb)->dev); 203 int err; 204 205 if (skb_is_gso(skb)) 206 return xfrm_output_gso(net, sk, skb); 207 208 if (skb->ip_summed == CHECKSUM_PARTIAL) { 209 err = skb_checksum_help(skb); 210 if (err) { 211 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR); 212 kfree_skb(skb); 213 return err; 214 } 215 } 216 217 return xfrm_output2(net, sk, skb); 218 } 219 EXPORT_SYMBOL_GPL(xfrm_output); 220 221 int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb) 222 { 223 struct xfrm_mode *inner_mode; 224 if (x->sel.family == AF_UNSPEC) 225 inner_mode = xfrm_ip2inner_mode(x, 226 xfrm_af2proto(skb_dst(skb)->ops->family)); 227 else 228 inner_mode = x->inner_mode; 229 230 if (inner_mode == NULL) 231 return -EAFNOSUPPORT; 232 return inner_mode->afinfo->extract_output(x, skb); 233 } 234 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output); 235 236 void xfrm_local_error(struct sk_buff *skb, int mtu) 237 { 238 unsigned int proto; 239 struct xfrm_state_afinfo *afinfo; 240 241 if (skb->protocol == htons(ETH_P_IP)) 242 proto = AF_INET; 243 else if (skb->protocol == htons(ETH_P_IPV6)) 244 proto = AF_INET6; 245 else 246 return; 247 248 afinfo = xfrm_state_get_afinfo(proto); 249 if (!afinfo) 250 return; 251 252 afinfo->local_error(skb, mtu); 253 xfrm_state_put_afinfo(afinfo); 254 } 255 EXPORT_SYMBOL_GPL(xfrm_local_error); 256