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(xfrm_dst_child(skb_dst(skb))); 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 skb->mark = xfrm_smark_get(skb->mark, x); 70 71 err = x->outer_mode->output(x, skb); 72 if (err) { 73 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR); 74 goto error_nolock; 75 } 76 77 spin_lock_bh(&x->lock); 78 79 if (unlikely(x->km.state != XFRM_STATE_VALID)) { 80 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID); 81 err = -EINVAL; 82 goto error; 83 } 84 85 err = xfrm_state_check_expire(x); 86 if (err) { 87 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED); 88 goto error; 89 } 90 91 err = x->repl->overflow(x, skb); 92 if (err) { 93 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR); 94 goto error; 95 } 96 97 x->curlft.bytes += skb->len; 98 x->curlft.packets++; 99 100 spin_unlock_bh(&x->lock); 101 102 skb_dst_force(skb); 103 if (!skb_dst(skb)) { 104 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR); 105 err = -EHOSTUNREACH; 106 goto error_nolock; 107 } 108 109 if (xfrm_offload(skb)) { 110 x->type_offload->encap(x, skb); 111 } else { 112 /* Inner headers are invalid now. */ 113 skb->encapsulation = 0; 114 115 err = x->type->output(x, skb); 116 if (err == -EINPROGRESS) 117 goto out; 118 } 119 120 resume: 121 if (err) { 122 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR); 123 goto error_nolock; 124 } 125 126 dst = skb_dst_pop(skb); 127 if (!dst) { 128 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR); 129 err = -EHOSTUNREACH; 130 goto error_nolock; 131 } 132 skb_dst_set(skb, dst); 133 x = dst->xfrm; 134 } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL)); 135 136 return 0; 137 138 error: 139 spin_unlock_bh(&x->lock); 140 error_nolock: 141 kfree_skb(skb); 142 out: 143 return err; 144 } 145 146 int xfrm_output_resume(struct sk_buff *skb, int err) 147 { 148 struct net *net = xs_net(skb_dst(skb)->xfrm); 149 150 while (likely((err = xfrm_output_one(skb, err)) == 0)) { 151 nf_reset(skb); 152 153 err = skb_dst(skb)->ops->local_out(net, skb->sk, skb); 154 if (unlikely(err != 1)) 155 goto out; 156 157 if (!skb_dst(skb)->xfrm) 158 return dst_output(net, skb->sk, skb); 159 160 err = nf_hook(skb_dst(skb)->ops->family, 161 NF_INET_POST_ROUTING, net, skb->sk, skb, 162 NULL, skb_dst(skb)->dev, xfrm_output2); 163 if (unlikely(err != 1)) 164 goto out; 165 } 166 167 if (err == -EINPROGRESS) 168 err = 0; 169 170 out: 171 return err; 172 } 173 EXPORT_SYMBOL_GPL(xfrm_output_resume); 174 175 static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb) 176 { 177 return xfrm_output_resume(skb, 1); 178 } 179 180 static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb) 181 { 182 struct sk_buff *segs; 183 184 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET); 185 BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_SGO_CB_OFFSET); 186 segs = skb_gso_segment(skb, 0); 187 kfree_skb(skb); 188 if (IS_ERR(segs)) 189 return PTR_ERR(segs); 190 if (segs == NULL) 191 return -EINVAL; 192 193 do { 194 struct sk_buff *nskb = segs->next; 195 int err; 196 197 skb_mark_not_on_list(segs); 198 err = xfrm_output2(net, sk, segs); 199 200 if (unlikely(err)) { 201 kfree_skb_list(nskb); 202 return err; 203 } 204 205 segs = nskb; 206 } while (segs); 207 208 return 0; 209 } 210 211 int xfrm_output(struct sock *sk, struct sk_buff *skb) 212 { 213 struct net *net = dev_net(skb_dst(skb)->dev); 214 struct xfrm_state *x = skb_dst(skb)->xfrm; 215 int err; 216 217 secpath_reset(skb); 218 219 if (xfrm_dev_offload_ok(skb, x)) { 220 struct sec_path *sp; 221 222 sp = secpath_set(skb); 223 if (!sp) { 224 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR); 225 kfree_skb(skb); 226 return -ENOMEM; 227 } 228 skb->encapsulation = 1; 229 230 sp->olen++; 231 sp->xvec[sp->len++] = x; 232 xfrm_state_hold(x); 233 234 if (skb_is_gso(skb)) { 235 skb_shinfo(skb)->gso_type |= SKB_GSO_ESP; 236 237 return xfrm_output2(net, sk, skb); 238 } 239 240 if (x->xso.dev && x->xso.dev->features & NETIF_F_HW_ESP_TX_CSUM) 241 goto out; 242 } 243 244 if (skb_is_gso(skb)) 245 return xfrm_output_gso(net, sk, skb); 246 247 if (skb->ip_summed == CHECKSUM_PARTIAL) { 248 err = skb_checksum_help(skb); 249 if (err) { 250 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR); 251 kfree_skb(skb); 252 return err; 253 } 254 } 255 256 out: 257 return xfrm_output2(net, sk, skb); 258 } 259 EXPORT_SYMBOL_GPL(xfrm_output); 260 261 int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb) 262 { 263 struct xfrm_mode *inner_mode; 264 if (x->sel.family == AF_UNSPEC) 265 inner_mode = xfrm_ip2inner_mode(x, 266 xfrm_af2proto(skb_dst(skb)->ops->family)); 267 else 268 inner_mode = x->inner_mode; 269 270 if (inner_mode == NULL) 271 return -EAFNOSUPPORT; 272 return inner_mode->afinfo->extract_output(x, skb); 273 } 274 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output); 275 276 void xfrm_local_error(struct sk_buff *skb, int mtu) 277 { 278 unsigned int proto; 279 struct xfrm_state_afinfo *afinfo; 280 281 if (skb->protocol == htons(ETH_P_IP)) 282 proto = AF_INET; 283 else if (skb->protocol == htons(ETH_P_IPV6)) 284 proto = AF_INET6; 285 else 286 return; 287 288 afinfo = xfrm_state_get_afinfo(proto); 289 if (afinfo) { 290 afinfo->local_error(skb, mtu); 291 rcu_read_unlock(); 292 } 293 } 294 EXPORT_SYMBOL_GPL(xfrm_local_error); 295