Herbert Xu | 6fccab6 | 2008-07-25 02:54:40 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * IP Payload Compression Protocol (IPComp) - RFC3173. |
| 3 | * |
| 4 | * Copyright (c) 2003 James Morris <jmorris@intercode.com.au> |
| 5 | * Copyright (c) 2003-2008 Herbert Xu <herbert@gondor.apana.org.au> |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify it |
| 8 | * under the terms of the GNU General Public License as published by the Free |
| 9 | * Software Foundation; either version 2 of the License, or (at your option) |
| 10 | * any later version. |
| 11 | * |
| 12 | * Todo: |
| 13 | * - Tunable compression parameters. |
| 14 | * - Compression stats. |
| 15 | * - Adaptive compression. |
| 16 | */ |
| 17 | |
| 18 | #include <linux/crypto.h> |
| 19 | #include <linux/err.h> |
| 20 | #include <linux/list.h> |
| 21 | #include <linux/module.h> |
| 22 | #include <linux/mutex.h> |
| 23 | #include <linux/percpu.h> |
| 24 | #include <linux/rtnetlink.h> |
| 25 | #include <linux/smp.h> |
| 26 | #include <linux/vmalloc.h> |
| 27 | #include <net/ip.h> |
| 28 | #include <net/ipcomp.h> |
| 29 | #include <net/xfrm.h> |
| 30 | |
| 31 | struct ipcomp_tfms { |
| 32 | struct list_head list; |
| 33 | struct crypto_comp **tfms; |
| 34 | int users; |
| 35 | }; |
| 36 | |
| 37 | static DEFINE_MUTEX(ipcomp_resource_mutex); |
| 38 | static void **ipcomp_scratches; |
| 39 | static int ipcomp_scratch_users; |
| 40 | static LIST_HEAD(ipcomp_tfms_list); |
| 41 | |
| 42 | static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb) |
| 43 | { |
| 44 | struct ipcomp_data *ipcd = x->data; |
| 45 | const int plen = skb->len; |
| 46 | int dlen = IPCOMP_SCRATCH_SIZE; |
| 47 | const u8 *start = skb->data; |
| 48 | const int cpu = get_cpu(); |
| 49 | u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu); |
| 50 | struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu); |
| 51 | int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen); |
| 52 | |
| 53 | if (err) |
| 54 | goto out; |
| 55 | |
| 56 | if (dlen < (plen + sizeof(struct ip_comp_hdr))) { |
| 57 | err = -EINVAL; |
| 58 | goto out; |
| 59 | } |
| 60 | |
| 61 | err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC); |
| 62 | if (err) |
| 63 | goto out; |
| 64 | |
| 65 | skb->truesize += dlen - plen; |
| 66 | __skb_put(skb, dlen - plen); |
| 67 | skb_copy_to_linear_data(skb, scratch, dlen); |
| 68 | out: |
| 69 | put_cpu(); |
| 70 | return err; |
| 71 | } |
| 72 | |
| 73 | int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb) |
| 74 | { |
| 75 | int nexthdr; |
| 76 | int err = -ENOMEM; |
| 77 | struct ip_comp_hdr *ipch; |
| 78 | |
| 79 | if (skb_linearize_cow(skb)) |
| 80 | goto out; |
| 81 | |
| 82 | skb->ip_summed = CHECKSUM_NONE; |
| 83 | |
| 84 | /* Remove ipcomp header and decompress original payload */ |
| 85 | ipch = (void *)skb->data; |
| 86 | nexthdr = ipch->nexthdr; |
| 87 | |
| 88 | skb->transport_header = skb->network_header + sizeof(*ipch); |
| 89 | __skb_pull(skb, sizeof(*ipch)); |
| 90 | err = ipcomp_decompress(x, skb); |
| 91 | if (err) |
| 92 | goto out; |
| 93 | |
| 94 | err = nexthdr; |
| 95 | |
| 96 | out: |
| 97 | return err; |
| 98 | } |
| 99 | EXPORT_SYMBOL_GPL(ipcomp_input); |
| 100 | |
| 101 | static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb) |
| 102 | { |
| 103 | struct ipcomp_data *ipcd = x->data; |
| 104 | const int plen = skb->len; |
| 105 | int dlen = IPCOMP_SCRATCH_SIZE; |
| 106 | u8 *start = skb->data; |
| 107 | const int cpu = get_cpu(); |
| 108 | u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu); |
| 109 | struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu); |
| 110 | int err; |
| 111 | |
| 112 | local_bh_disable(); |
| 113 | err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); |
| 114 | local_bh_enable(); |
| 115 | if (err) |
| 116 | goto out; |
| 117 | |
| 118 | if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) { |
| 119 | err = -EMSGSIZE; |
| 120 | goto out; |
| 121 | } |
| 122 | |
| 123 | memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); |
| 124 | put_cpu(); |
| 125 | |
| 126 | pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr)); |
| 127 | return 0; |
| 128 | |
| 129 | out: |
| 130 | put_cpu(); |
| 131 | return err; |
| 132 | } |
| 133 | |
| 134 | int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb) |
| 135 | { |
| 136 | int err; |
| 137 | struct ip_comp_hdr *ipch; |
| 138 | struct ipcomp_data *ipcd = x->data; |
| 139 | |
| 140 | if (skb->len < ipcd->threshold) { |
| 141 | /* Don't bother compressing */ |
| 142 | goto out_ok; |
| 143 | } |
| 144 | |
| 145 | if (skb_linearize_cow(skb)) |
| 146 | goto out_ok; |
| 147 | |
| 148 | err = ipcomp_compress(x, skb); |
| 149 | |
| 150 | if (err) { |
| 151 | goto out_ok; |
| 152 | } |
| 153 | |
| 154 | /* Install ipcomp header, convert into ipcomp datagram. */ |
| 155 | ipch = ip_comp_hdr(skb); |
| 156 | ipch->nexthdr = *skb_mac_header(skb); |
| 157 | ipch->flags = 0; |
| 158 | ipch->cpi = htons((u16 )ntohl(x->id.spi)); |
| 159 | *skb_mac_header(skb) = IPPROTO_COMP; |
| 160 | out_ok: |
| 161 | skb_push(skb, -skb_network_offset(skb)); |
| 162 | return 0; |
| 163 | } |
| 164 | EXPORT_SYMBOL_GPL(ipcomp_output); |
| 165 | |
| 166 | static void ipcomp_free_scratches(void) |
| 167 | { |
| 168 | int i; |
| 169 | void **scratches; |
| 170 | |
| 171 | if (--ipcomp_scratch_users) |
| 172 | return; |
| 173 | |
| 174 | scratches = ipcomp_scratches; |
| 175 | if (!scratches) |
| 176 | return; |
| 177 | |
| 178 | for_each_possible_cpu(i) |
| 179 | vfree(*per_cpu_ptr(scratches, i)); |
| 180 | |
| 181 | free_percpu(scratches); |
| 182 | } |
| 183 | |
| 184 | static void **ipcomp_alloc_scratches(void) |
| 185 | { |
| 186 | int i; |
| 187 | void **scratches; |
| 188 | |
| 189 | if (ipcomp_scratch_users++) |
| 190 | return ipcomp_scratches; |
| 191 | |
| 192 | scratches = alloc_percpu(void *); |
| 193 | if (!scratches) |
| 194 | return NULL; |
| 195 | |
| 196 | ipcomp_scratches = scratches; |
| 197 | |
| 198 | for_each_possible_cpu(i) { |
| 199 | void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); |
| 200 | if (!scratch) |
| 201 | return NULL; |
| 202 | *per_cpu_ptr(scratches, i) = scratch; |
| 203 | } |
| 204 | |
| 205 | return scratches; |
| 206 | } |
| 207 | |
| 208 | static void ipcomp_free_tfms(struct crypto_comp **tfms) |
| 209 | { |
| 210 | struct ipcomp_tfms *pos; |
| 211 | int cpu; |
| 212 | |
| 213 | list_for_each_entry(pos, &ipcomp_tfms_list, list) { |
| 214 | if (pos->tfms == tfms) |
| 215 | break; |
| 216 | } |
| 217 | |
| 218 | BUG_TRAP(pos); |
| 219 | |
| 220 | if (--pos->users) |
| 221 | return; |
| 222 | |
| 223 | list_del(&pos->list); |
| 224 | kfree(pos); |
| 225 | |
| 226 | if (!tfms) |
| 227 | return; |
| 228 | |
| 229 | for_each_possible_cpu(cpu) { |
| 230 | struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu); |
| 231 | crypto_free_comp(tfm); |
| 232 | } |
| 233 | free_percpu(tfms); |
| 234 | } |
| 235 | |
| 236 | static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name) |
| 237 | { |
| 238 | struct ipcomp_tfms *pos; |
| 239 | struct crypto_comp **tfms; |
| 240 | int cpu; |
| 241 | |
| 242 | /* This can be any valid CPU ID so we don't need locking. */ |
| 243 | cpu = raw_smp_processor_id(); |
| 244 | |
| 245 | list_for_each_entry(pos, &ipcomp_tfms_list, list) { |
| 246 | struct crypto_comp *tfm; |
| 247 | |
| 248 | tfms = pos->tfms; |
| 249 | tfm = *per_cpu_ptr(tfms, cpu); |
| 250 | |
| 251 | if (!strcmp(crypto_comp_name(tfm), alg_name)) { |
| 252 | pos->users++; |
| 253 | return tfms; |
| 254 | } |
| 255 | } |
| 256 | |
| 257 | pos = kmalloc(sizeof(*pos), GFP_KERNEL); |
| 258 | if (!pos) |
| 259 | return NULL; |
| 260 | |
| 261 | pos->users = 1; |
| 262 | INIT_LIST_HEAD(&pos->list); |
| 263 | list_add(&pos->list, &ipcomp_tfms_list); |
| 264 | |
| 265 | pos->tfms = tfms = alloc_percpu(struct crypto_comp *); |
| 266 | if (!tfms) |
| 267 | goto error; |
| 268 | |
| 269 | for_each_possible_cpu(cpu) { |
| 270 | struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0, |
| 271 | CRYPTO_ALG_ASYNC); |
| 272 | if (IS_ERR(tfm)) |
| 273 | goto error; |
| 274 | *per_cpu_ptr(tfms, cpu) = tfm; |
| 275 | } |
| 276 | |
| 277 | return tfms; |
| 278 | |
| 279 | error: |
| 280 | ipcomp_free_tfms(tfms); |
| 281 | return NULL; |
| 282 | } |
| 283 | |
| 284 | static void ipcomp_free_data(struct ipcomp_data *ipcd) |
| 285 | { |
| 286 | if (ipcd->tfms) |
| 287 | ipcomp_free_tfms(ipcd->tfms); |
| 288 | ipcomp_free_scratches(); |
| 289 | } |
| 290 | |
| 291 | void ipcomp_destroy(struct xfrm_state *x) |
| 292 | { |
| 293 | struct ipcomp_data *ipcd = x->data; |
| 294 | if (!ipcd) |
| 295 | return; |
| 296 | xfrm_state_delete_tunnel(x); |
| 297 | mutex_lock(&ipcomp_resource_mutex); |
| 298 | ipcomp_free_data(ipcd); |
| 299 | mutex_unlock(&ipcomp_resource_mutex); |
| 300 | kfree(ipcd); |
| 301 | } |
| 302 | EXPORT_SYMBOL_GPL(ipcomp_destroy); |
| 303 | |
| 304 | int ipcomp_init_state(struct xfrm_state *x) |
| 305 | { |
| 306 | int err; |
| 307 | struct ipcomp_data *ipcd; |
| 308 | struct xfrm_algo_desc *calg_desc; |
| 309 | |
| 310 | err = -EINVAL; |
| 311 | if (!x->calg) |
| 312 | goto out; |
| 313 | |
| 314 | if (x->encap) |
| 315 | goto out; |
| 316 | |
| 317 | err = -ENOMEM; |
| 318 | ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL); |
| 319 | if (!ipcd) |
| 320 | goto out; |
| 321 | |
| 322 | mutex_lock(&ipcomp_resource_mutex); |
| 323 | if (!ipcomp_alloc_scratches()) |
| 324 | goto error; |
| 325 | |
| 326 | ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name); |
| 327 | if (!ipcd->tfms) |
| 328 | goto error; |
| 329 | mutex_unlock(&ipcomp_resource_mutex); |
| 330 | |
| 331 | calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); |
| 332 | BUG_ON(!calg_desc); |
| 333 | ipcd->threshold = calg_desc->uinfo.comp.threshold; |
| 334 | x->data = ipcd; |
| 335 | err = 0; |
| 336 | out: |
| 337 | return err; |
| 338 | |
| 339 | error: |
| 340 | ipcomp_free_data(ipcd); |
| 341 | mutex_unlock(&ipcomp_resource_mutex); |
| 342 | kfree(ipcd); |
| 343 | goto out; |
| 344 | } |
| 345 | EXPORT_SYMBOL_GPL(ipcomp_init_state); |
| 346 | |
| 347 | MODULE_LICENSE("GPL"); |
| 348 | MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173"); |
| 349 | MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); |