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