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