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