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 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 err = x->outer_mode->output(x, skb); 70 if (err) { 71 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR); 72 goto error_nolock; 73 } 74 75 spin_lock_bh(&x->lock); 76 77 if (unlikely(x->km.state != XFRM_STATE_VALID)) { 78 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID); 79 err = -EINVAL; 80 goto error; 81 } 82 83 err = xfrm_state_check_expire(x); 84 if (err) { 85 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED); 86 goto error; 87 } 88 89 err = x->repl->overflow(x, skb); 90 if (err) { 91 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR); 92 goto error; 93 } 94 95 x->curlft.bytes += skb->len; 96 x->curlft.packets++; 97 98 spin_unlock_bh(&x->lock); 99 100 skb_dst_force(skb); 101 102 err = x->type->output(x, skb); 103 if (err == -EINPROGRESS) 104 goto out; 105 106 resume: 107 if (err) { 108 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR); 109 goto error_nolock; 110 } 111 112 dst = skb_dst_pop(skb); 113 if (!dst) { 114 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR); 115 err = -EHOSTUNREACH; 116 goto error_nolock; 117 } 118 skb_dst_set(skb, dst); 119 x = dst->xfrm; 120 } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL)); 121 122 return 0; 123 124 error: 125 spin_unlock_bh(&x->lock); 126 error_nolock: 127 kfree_skb(skb); 128 out: 129 return err; 130 } 131 132 int xfrm_output_resume(struct sk_buff *skb, int err) 133 { 134 while (likely((err = xfrm_output_one(skb, err)) == 0)) { 135 nf_reset(skb); 136 137 err = skb_dst(skb)->ops->local_out(skb); 138 if (unlikely(err != 1)) 139 goto out; 140 141 if (!skb_dst(skb)->xfrm) 142 return dst_output(skb); 143 144 err = nf_hook(skb_dst(skb)->ops->family, 145 NF_INET_POST_ROUTING, skb->sk, skb, 146 NULL, skb_dst(skb)->dev, xfrm_output2); 147 if (unlikely(err != 1)) 148 goto out; 149 } 150 151 if (err == -EINPROGRESS) 152 err = 0; 153 154 out: 155 return err; 156 } 157 EXPORT_SYMBOL_GPL(xfrm_output_resume); 158 159 static int xfrm_output2(struct sock *sk, struct sk_buff *skb) 160 { 161 return xfrm_output_resume(skb, 1); 162 } 163 164 static int xfrm_output_gso(struct sock *sk, struct sk_buff *skb) 165 { 166 struct sk_buff *segs; 167 168 segs = skb_gso_segment(skb, 0); 169 kfree_skb(skb); 170 if (IS_ERR(segs)) 171 return PTR_ERR(segs); 172 if (segs == NULL) 173 return -EINVAL; 174 175 do { 176 struct sk_buff *nskb = segs->next; 177 int err; 178 179 segs->next = NULL; 180 err = xfrm_output2(sk, segs); 181 182 if (unlikely(err)) { 183 kfree_skb_list(nskb); 184 return err; 185 } 186 187 segs = nskb; 188 } while (segs); 189 190 return 0; 191 } 192 193 int xfrm_output(struct sock *sk, struct sk_buff *skb) 194 { 195 struct net *net = dev_net(skb_dst(skb)->dev); 196 int err; 197 198 if (skb_is_gso(skb)) 199 return xfrm_output_gso(sk, skb); 200 201 if (skb->ip_summed == CHECKSUM_PARTIAL) { 202 err = skb_checksum_help(skb); 203 if (err) { 204 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR); 205 kfree_skb(skb); 206 return err; 207 } 208 } 209 210 return xfrm_output2(sk, skb); 211 } 212 EXPORT_SYMBOL_GPL(xfrm_output); 213 214 int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb) 215 { 216 struct xfrm_mode *inner_mode; 217 if (x->sel.family == AF_UNSPEC) 218 inner_mode = xfrm_ip2inner_mode(x, 219 xfrm_af2proto(skb_dst(skb)->ops->family)); 220 else 221 inner_mode = x->inner_mode; 222 223 if (inner_mode == NULL) 224 return -EAFNOSUPPORT; 225 return inner_mode->afinfo->extract_output(x, skb); 226 } 227 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output); 228 229 void xfrm_local_error(struct sk_buff *skb, int mtu) 230 { 231 unsigned int proto; 232 struct xfrm_state_afinfo *afinfo; 233 234 if (skb->protocol == htons(ETH_P_IP)) 235 proto = AF_INET; 236 else if (skb->protocol == htons(ETH_P_IPV6)) 237 proto = AF_INET6; 238 else 239 return; 240 241 afinfo = xfrm_state_get_afinfo(proto); 242 if (!afinfo) 243 return; 244 245 afinfo->local_error(skb, mtu); 246 xfrm_state_put_afinfo(afinfo); 247 } 248 EXPORT_SYMBOL_GPL(xfrm_local_error); 249