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 goto error_nolock; 106 } 107 108 if (xfrm_offload(skb)) { 109 x->type_offload->encap(x, skb); 110 } else { 111 /* Inner headers are invalid now. */ 112 skb->encapsulation = 0; 113 114 err = x->type->output(x, skb); 115 if (err == -EINPROGRESS) 116 goto out; 117 } 118 119 resume: 120 if (err) { 121 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR); 122 goto error_nolock; 123 } 124 125 dst = skb_dst_pop(skb); 126 if (!dst) { 127 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR); 128 err = -EHOSTUNREACH; 129 goto error_nolock; 130 } 131 skb_dst_set(skb, dst); 132 x = dst->xfrm; 133 } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL)); 134 135 return 0; 136 137 error: 138 spin_unlock_bh(&x->lock); 139 error_nolock: 140 kfree_skb(skb); 141 out: 142 return err; 143 } 144 145 int xfrm_output_resume(struct sk_buff *skb, int err) 146 { 147 struct net *net = xs_net(skb_dst(skb)->xfrm); 148 149 while (likely((err = xfrm_output_one(skb, err)) == 0)) { 150 nf_reset(skb); 151 152 err = skb_dst(skb)->ops->local_out(net, skb->sk, skb); 153 if (unlikely(err != 1)) 154 goto out; 155 156 if (!skb_dst(skb)->xfrm) 157 return dst_output(net, skb->sk, skb); 158 159 err = nf_hook(skb_dst(skb)->ops->family, 160 NF_INET_POST_ROUTING, net, skb->sk, skb, 161 NULL, skb_dst(skb)->dev, xfrm_output2); 162 if (unlikely(err != 1)) 163 goto out; 164 } 165 166 if (err == -EINPROGRESS) 167 err = 0; 168 169 out: 170 return err; 171 } 172 EXPORT_SYMBOL_GPL(xfrm_output_resume); 173 174 static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb) 175 { 176 return xfrm_output_resume(skb, 1); 177 } 178 179 static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb) 180 { 181 struct sk_buff *segs; 182 183 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET); 184 BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_SGO_CB_OFFSET); 185 segs = skb_gso_segment(skb, 0); 186 kfree_skb(skb); 187 if (IS_ERR(segs)) 188 return PTR_ERR(segs); 189 if (segs == NULL) 190 return -EINVAL; 191 192 do { 193 struct sk_buff *nskb = segs->next; 194 int err; 195 196 skb_mark_not_on_list(segs); 197 err = xfrm_output2(net, sk, segs); 198 199 if (unlikely(err)) { 200 kfree_skb_list(nskb); 201 return err; 202 } 203 204 segs = nskb; 205 } while (segs); 206 207 return 0; 208 } 209 210 int xfrm_output(struct sock *sk, struct sk_buff *skb) 211 { 212 struct net *net = dev_net(skb_dst(skb)->dev); 213 struct xfrm_state *x = skb_dst(skb)->xfrm; 214 int err; 215 216 secpath_reset(skb); 217 218 if (xfrm_dev_offload_ok(skb, x)) { 219 struct sec_path *sp; 220 221 sp = secpath_dup(skb->sp); 222 if (!sp) { 223 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR); 224 kfree_skb(skb); 225 return -ENOMEM; 226 } 227 if (skb->sp) 228 secpath_put(skb->sp); 229 skb->sp = sp; 230 skb->encapsulation = 1; 231 232 sp->olen++; 233 sp->xvec[skb->sp->len++] = x; 234 xfrm_state_hold(x); 235 236 if (skb_is_gso(skb)) { 237 skb_shinfo(skb)->gso_type |= SKB_GSO_ESP; 238 239 return xfrm_output2(net, sk, skb); 240 } 241 242 if (x->xso.dev && x->xso.dev->features & NETIF_F_HW_ESP_TX_CSUM) 243 goto out; 244 } 245 246 if (skb_is_gso(skb)) 247 return xfrm_output_gso(net, sk, skb); 248 249 if (skb->ip_summed == CHECKSUM_PARTIAL) { 250 err = skb_checksum_help(skb); 251 if (err) { 252 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR); 253 kfree_skb(skb); 254 return err; 255 } 256 } 257 258 out: 259 return xfrm_output2(net, sk, skb); 260 } 261 EXPORT_SYMBOL_GPL(xfrm_output); 262 263 int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb) 264 { 265 struct xfrm_mode *inner_mode; 266 if (x->sel.family == AF_UNSPEC) 267 inner_mode = xfrm_ip2inner_mode(x, 268 xfrm_af2proto(skb_dst(skb)->ops->family)); 269 else 270 inner_mode = x->inner_mode; 271 272 if (inner_mode == NULL) 273 return -EAFNOSUPPORT; 274 return inner_mode->afinfo->extract_output(x, skb); 275 } 276 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output); 277 278 void xfrm_local_error(struct sk_buff *skb, int mtu) 279 { 280 unsigned int proto; 281 struct xfrm_state_afinfo *afinfo; 282 283 if (skb->protocol == htons(ETH_P_IP)) 284 proto = AF_INET; 285 else if (skb->protocol == htons(ETH_P_IPV6)) 286 proto = AF_INET6; 287 else 288 return; 289 290 afinfo = xfrm_state_get_afinfo(proto); 291 if (afinfo) { 292 afinfo->local_error(skb, mtu); 293 rcu_read_unlock(); 294 } 295 } 296 EXPORT_SYMBOL_GPL(xfrm_local_error); 297