| 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 | 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 | struct net *net = xs_net(skb_dst(skb)->xfrm); |
| 135 | |
| 136 | while (likely((err = xfrm_output_one(skb, err)) == 0)) { |
| 137 | nf_reset(skb); |
| 138 | |
| 139 | err = skb_dst(skb)->ops->local_out(net, skb->sk, skb); |
| 140 | if (unlikely(err != 1)) |
| 141 | goto out; |
| 142 | |
| 143 | if (!skb_dst(skb)->xfrm) |
| 144 | return dst_output(net, skb->sk, skb); |
| 145 | |
| 146 | err = nf_hook(skb_dst(skb)->ops->family, |
| 147 | NF_INET_POST_ROUTING, net, skb->sk, skb, |
| 148 | NULL, skb_dst(skb)->dev, xfrm_output2); |
| 149 | if (unlikely(err != 1)) |
| 150 | goto out; |
| 151 | } |
| 152 | |
| 153 | if (err == -EINPROGRESS) |
| 154 | err = 0; |
| 155 | |
| 156 | out: |
| 157 | return err; |
| 158 | } |
| 159 | EXPORT_SYMBOL_GPL(xfrm_output_resume); |
| 160 | |
| 161 | static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb) |
| 162 | { |
| 163 | return xfrm_output_resume(skb, 1); |
| 164 | } |
| 165 | |
| 166 | static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb) |
| 167 | { |
| 168 | struct sk_buff *segs; |
| 169 | |
| 170 | BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET); |
| 171 | BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_SGO_CB_OFFSET); |
| 172 | segs = skb_gso_segment(skb, 0); |
| 173 | kfree_skb(skb); |
| 174 | if (IS_ERR(segs)) |
| 175 | return PTR_ERR(segs); |
| 176 | if (segs == NULL) |
| 177 | return -EINVAL; |
| 178 | |
| 179 | do { |
| 180 | struct sk_buff *nskb = segs->next; |
| 181 | int err; |
| 182 | |
| 183 | segs->next = NULL; |
| 184 | err = xfrm_output2(net, sk, segs); |
| 185 | |
| 186 | if (unlikely(err)) { |
| 187 | kfree_skb_list(nskb); |
| 188 | return err; |
| 189 | } |
| 190 | |
| 191 | segs = nskb; |
| 192 | } while (segs); |
| 193 | |
| 194 | return 0; |
| 195 | } |
| 196 | |
| 197 | int xfrm_output(struct sock *sk, struct sk_buff *skb) |
| 198 | { |
| 199 | struct net *net = dev_net(skb_dst(skb)->dev); |
| 200 | int err; |
| 201 | |
| 202 | if (skb_is_gso(skb)) |
| 203 | return xfrm_output_gso(net, sk, skb); |
| 204 | |
| 205 | if (skb->ip_summed == CHECKSUM_PARTIAL) { |
| 206 | err = skb_checksum_help(skb); |
| 207 | if (err) { |
| 208 | XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR); |
| 209 | kfree_skb(skb); |
| 210 | return err; |
| 211 | } |
| 212 | } |
| 213 | |
| 214 | return xfrm_output2(net, sk, skb); |
| 215 | } |
| 216 | EXPORT_SYMBOL_GPL(xfrm_output); |
| 217 | |
| 218 | int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb) |
| 219 | { |
| 220 | struct xfrm_mode *inner_mode; |
| 221 | if (x->sel.family == AF_UNSPEC) |
| 222 | inner_mode = xfrm_ip2inner_mode(x, |
| 223 | xfrm_af2proto(skb_dst(skb)->ops->family)); |
| 224 | else |
| 225 | inner_mode = x->inner_mode; |
| 226 | |
| 227 | if (inner_mode == NULL) |
| 228 | return -EAFNOSUPPORT; |
| 229 | return inner_mode->afinfo->extract_output(x, skb); |
| 230 | } |
| 231 | EXPORT_SYMBOL_GPL(xfrm_inner_extract_output); |
| 232 | |
| 233 | void xfrm_local_error(struct sk_buff *skb, int mtu) |
| 234 | { |
| 235 | unsigned int proto; |
| 236 | struct xfrm_state_afinfo *afinfo; |
| 237 | |
| 238 | if (skb->protocol == htons(ETH_P_IP)) |
| 239 | proto = AF_INET; |
| 240 | else if (skb->protocol == htons(ETH_P_IPV6)) |
| 241 | proto = AF_INET6; |
| 242 | else |
| 243 | return; |
| 244 | |
| 245 | afinfo = xfrm_state_get_afinfo(proto); |
| 246 | if (!afinfo) |
| 247 | return; |
| 248 | |
| 249 | afinfo->local_error(skb, mtu); |
| 250 | xfrm_state_put_afinfo(afinfo); |
| 251 | } |
| 252 | EXPORT_SYMBOL_GPL(xfrm_local_error); |