1 /* 2 * 6LoWPAN next header compression 3 * 4 * 5 * Authors: 6 * Alexander Aring <aar@pengutronix.de> 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License 10 * as published by the Free Software Foundation; either version 11 * 2 of the License, or (at your option) any later version. 12 */ 13 14 #include <linux/netdevice.h> 15 16 #include <net/ipv6.h> 17 18 #include "nhc.h" 19 20 static struct rb_root rb_root = RB_ROOT; 21 static struct lowpan_nhc *lowpan_nexthdr_nhcs[NEXTHDR_MAX]; 22 static DEFINE_SPINLOCK(lowpan_nhc_lock); 23 24 static int lowpan_nhc_insert(struct lowpan_nhc *nhc) 25 { 26 struct rb_node **new = &rb_root.rb_node, *parent = NULL; 27 28 /* Figure out where to put new node */ 29 while (*new) { 30 struct lowpan_nhc *this = rb_entry(*new, struct lowpan_nhc, 31 node); 32 int result, len_dif, len; 33 34 len_dif = nhc->idlen - this->idlen; 35 36 if (nhc->idlen < this->idlen) 37 len = nhc->idlen; 38 else 39 len = this->idlen; 40 41 result = memcmp(nhc->id, this->id, len); 42 if (!result) 43 result = len_dif; 44 45 parent = *new; 46 if (result < 0) 47 new = &((*new)->rb_left); 48 else if (result > 0) 49 new = &((*new)->rb_right); 50 else 51 return -EEXIST; 52 } 53 54 /* Add new node and rebalance tree. */ 55 rb_link_node(&nhc->node, parent, new); 56 rb_insert_color(&nhc->node, &rb_root); 57 58 return 0; 59 } 60 61 static void lowpan_nhc_remove(struct lowpan_nhc *nhc) 62 { 63 rb_erase(&nhc->node, &rb_root); 64 } 65 66 static struct lowpan_nhc *lowpan_nhc_by_nhcid(const struct sk_buff *skb) 67 { 68 struct rb_node *node = rb_root.rb_node; 69 const u8 *nhcid_skb_ptr = skb->data; 70 71 while (node) { 72 struct lowpan_nhc *nhc = rb_entry(node, struct lowpan_nhc, 73 node); 74 u8 nhcid_skb_ptr_masked[LOWPAN_NHC_MAX_ID_LEN]; 75 int result, i; 76 77 if (nhcid_skb_ptr + nhc->idlen > skb->data + skb->len) 78 return NULL; 79 80 /* copy and mask afterwards the nhid value from skb */ 81 memcpy(nhcid_skb_ptr_masked, nhcid_skb_ptr, nhc->idlen); 82 for (i = 0; i < nhc->idlen; i++) 83 nhcid_skb_ptr_masked[i] &= nhc->idmask[i]; 84 85 result = memcmp(nhcid_skb_ptr_masked, nhc->id, nhc->idlen); 86 if (result < 0) 87 node = node->rb_left; 88 else if (result > 0) 89 node = node->rb_right; 90 else 91 return nhc; 92 } 93 94 return NULL; 95 } 96 97 int lowpan_nhc_check_compression(struct sk_buff *skb, 98 const struct ipv6hdr *hdr, u8 **hc_ptr) 99 { 100 struct lowpan_nhc *nhc; 101 int ret = 0; 102 103 spin_lock_bh(&lowpan_nhc_lock); 104 105 nhc = lowpan_nexthdr_nhcs[hdr->nexthdr]; 106 if (!(nhc && nhc->compress)) 107 ret = -ENOENT; 108 109 spin_unlock_bh(&lowpan_nhc_lock); 110 111 return ret; 112 } 113 114 int lowpan_nhc_do_compression(struct sk_buff *skb, const struct ipv6hdr *hdr, 115 u8 **hc_ptr) 116 { 117 int ret; 118 struct lowpan_nhc *nhc; 119 120 spin_lock_bh(&lowpan_nhc_lock); 121 122 nhc = lowpan_nexthdr_nhcs[hdr->nexthdr]; 123 /* check if the nhc module was removed in unlocked part. 124 * TODO: this is a workaround we should prevent unloading 125 * of nhc modules while unlocked part, this will always drop 126 * the lowpan packet but it's very unlikely. 127 * 128 * Solution isn't easy because we need to decide at 129 * lowpan_nhc_check_compression if we do a compression or not. 130 * Because the inline data which is added to skb, we can't move this 131 * handling. 132 */ 133 if (unlikely(!nhc || !nhc->compress)) { 134 ret = -EINVAL; 135 goto out; 136 } 137 138 /* In the case of RAW sockets the transport header is not set by 139 * the ip6 stack so we must set it ourselves 140 */ 141 if (skb->transport_header == skb->network_header) 142 skb_set_transport_header(skb, sizeof(struct ipv6hdr)); 143 144 ret = nhc->compress(skb, hc_ptr); 145 if (ret < 0) 146 goto out; 147 148 /* skip the transport header */ 149 skb_pull(skb, nhc->nexthdrlen); 150 151 out: 152 spin_unlock_bh(&lowpan_nhc_lock); 153 154 return ret; 155 } 156 157 int lowpan_nhc_do_uncompression(struct sk_buff *skb, 158 const struct net_device *dev, 159 struct ipv6hdr *hdr) 160 { 161 struct lowpan_nhc *nhc; 162 int ret; 163 164 spin_lock_bh(&lowpan_nhc_lock); 165 166 nhc = lowpan_nhc_by_nhcid(skb); 167 if (nhc) { 168 if (nhc->uncompress) { 169 ret = nhc->uncompress(skb, sizeof(struct ipv6hdr) + 170 nhc->nexthdrlen); 171 if (ret < 0) { 172 spin_unlock_bh(&lowpan_nhc_lock); 173 return ret; 174 } 175 } else { 176 spin_unlock_bh(&lowpan_nhc_lock); 177 netdev_warn(dev, "received nhc id for %s which is not implemented.\n", 178 nhc->name); 179 return -ENOTSUPP; 180 } 181 } else { 182 spin_unlock_bh(&lowpan_nhc_lock); 183 netdev_warn(dev, "received unknown nhc id which was not found.\n"); 184 return -ENOENT; 185 } 186 187 hdr->nexthdr = nhc->nexthdr; 188 skb_reset_transport_header(skb); 189 raw_dump_table(__func__, "raw transport header dump", 190 skb_transport_header(skb), nhc->nexthdrlen); 191 192 spin_unlock_bh(&lowpan_nhc_lock); 193 194 return 0; 195 } 196 197 int lowpan_nhc_add(struct lowpan_nhc *nhc) 198 { 199 int ret; 200 201 if (!nhc->idlen || !nhc->idsetup) 202 return -EINVAL; 203 204 WARN_ONCE(nhc->idlen > LOWPAN_NHC_MAX_ID_LEN, 205 "LOWPAN_NHC_MAX_ID_LEN should be updated to %zd.\n", 206 nhc->idlen); 207 208 nhc->idsetup(nhc); 209 210 spin_lock_bh(&lowpan_nhc_lock); 211 212 if (lowpan_nexthdr_nhcs[nhc->nexthdr]) { 213 ret = -EEXIST; 214 goto out; 215 } 216 217 ret = lowpan_nhc_insert(nhc); 218 if (ret < 0) 219 goto out; 220 221 lowpan_nexthdr_nhcs[nhc->nexthdr] = nhc; 222 out: 223 spin_unlock_bh(&lowpan_nhc_lock); 224 return ret; 225 } 226 EXPORT_SYMBOL(lowpan_nhc_add); 227 228 void lowpan_nhc_del(struct lowpan_nhc *nhc) 229 { 230 spin_lock_bh(&lowpan_nhc_lock); 231 232 lowpan_nhc_remove(nhc); 233 lowpan_nexthdr_nhcs[nhc->nexthdr] = NULL; 234 235 spin_unlock_bh(&lowpan_nhc_lock); 236 237 synchronize_net(); 238 } 239 EXPORT_SYMBOL(lowpan_nhc_del); 240