net/xfrm/xfrm_ipcomp.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * IP Payload Compression Protocol (IPComp) - RFC3173.
   4  *
   5  * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
   6  * Copyright (c) 2003-2008 Herbert Xu <herbert@gondor.apana.org.au>
   7  *
   8  * Todo:
   9  *   - Tunable compression parameters.
  10  *   - Compression stats.
  11  *   - Adaptive compression.
  12  */
  13
  14 #include <linux/crypto.h>
  15 #include <linux/err.h>
  16 #include <linux/list.h>
  17 #include <linux/module.h>
  18 #include <linux/mutex.h>
  19 #include <linux/percpu.h>
  20 #include <linux/slab.h>
  21 #include <linux/smp.h>
  22 #include <linux/vmalloc.h>
  23 #include <net/ip.h>
  24 #include <net/ipcomp.h>
  25 #include <net/xfrm.h>
  26
  27 struct ipcomp_tfms {
  28         struct list_head list;
  29         struct crypto_comp * __percpu *tfms;
  30         int users;
  31 };
  32
  33 static DEFINE_MUTEX(ipcomp_resource_mutex);
  34 static void * __percpu *ipcomp_scratches;
  35 static int ipcomp_scratch_users;
  36 static LIST_HEAD(ipcomp_tfms_list);
  37
  38 static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
  39 {
  40         struct ipcomp_data *ipcd = x->data;
  41         const int plen = skb->len;
  42         int dlen = IPCOMP_SCRATCH_SIZE;
  43         const u8 *start = skb->data;
  44         const int cpu = get_cpu();
  45         u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
  46         struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
  47         int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
  48         int len;
  49
  50         if (err)
  51                 goto out;
  52
  53         if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
  54                 err = -EINVAL;
  55                 goto out;
  56         }
  57
  58         len = dlen - plen;
  59         if (len > skb_tailroom(skb))
  60                 len = skb_tailroom(skb);
  61
  62         __skb_put(skb, len);
  63
  64         len += plen;
  65         skb_copy_to_linear_data(skb, scratch, len);
  66
  67         while ((scratch += len, dlen -= len) > 0) {
  68                 skb_frag_t *frag;
  69                 struct page *page;
  70
  71                 err = -EMSGSIZE;
  72                 if (WARN_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS))
  73                         goto out;
  74
  75                 frag = skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;
  76                 page = alloc_page(GFP_ATOMIC);
  77
  78                 err = -ENOMEM;
  79                 if (!page)
  80                         goto out;
  81
  82                 __skb_frag_set_page(frag, page);
  83
  84                 len = PAGE_SIZE;
  85                 if (dlen < len)
  86                         len = dlen;
  87
  88                 skb_frag_off_set(frag, 0);
  89                 skb_frag_size_set(frag, len);
  90                 memcpy(skb_frag_address(frag), scratch, len);
  91
  92                 skb->truesize += len;
  93                 skb->data_len += len;
  94                 skb->len += len;
  95
  96                 skb_shinfo(skb)->nr_frags++;
  97         }
  98
  99         err = 0;
 100
 101 out:
 102         put_cpu();
 103         return err;
 104 }
 105
 106 int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
 107 {
 108         int nexthdr;
 109         int err = -ENOMEM;
 110         struct ip_comp_hdr *ipch;
 111
 112         if (skb_linearize_cow(skb))
 113                 goto out;
 114
 115         skb->ip_summed = CHECKSUM_NONE;
 116
 117         /* Remove ipcomp header and decompress original payload */
 118         ipch = (void *)skb->data;
 119         nexthdr = ipch->nexthdr;
 120
 121         skb->transport_header = skb->network_header + sizeof(*ipch);
 122         __skb_pull(skb, sizeof(*ipch));
 123         err = ipcomp_decompress(x, skb);
 124         if (err)
 125                 goto out;
 126
 127         err = nexthdr;
 128
 129 out:
 130         return err;
 131 }
 132 EXPORT_SYMBOL_GPL(ipcomp_input);
 133
 134 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
 135 {
 136         struct ipcomp_data *ipcd = x->data;
 137         const int plen = skb->len;
 138         int dlen = IPCOMP_SCRATCH_SIZE;
 139         u8 *start = skb->data;
 140         struct crypto_comp *tfm;
 141         u8 *scratch;
 142         int err;
 143
 144         local_bh_disable();
 145         scratch = *this_cpu_ptr(ipcomp_scratches);
 146         tfm = *this_cpu_ptr(ipcd->tfms);
 147         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 148         if (err)
 149                 goto out;
 150
 151         if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
 152                 err = -EMSGSIZE;
 153                 goto out;
 154         }
 155
 156         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 157         local_bh_enable();
 158
 159         pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
 160         return 0;
 161
 162 out:
 163         local_bh_enable();
 164         return err;
 165 }
 166
 167 int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
 168 {
 169         int err;
 170         struct ip_comp_hdr *ipch;
 171         struct ipcomp_data *ipcd = x->data;
 172
 173         if (skb->len < ipcd->threshold) {
 174                 /* Don't bother compressing */
 175                 goto out_ok;
 176         }
 177
 178         if (skb_linearize_cow(skb))
 179                 goto out_ok;
 180
 181         err = ipcomp_compress(x, skb);
 182
 183         if (err) {
 184                 goto out_ok;
 185         }
 186
 187         /* Install ipcomp header, convert into ipcomp datagram. */
 188         ipch = ip_comp_hdr(skb);
 189         ipch->nexthdr = *skb_mac_header(skb);
 190         ipch->flags = 0;
 191         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 192         *skb_mac_header(skb) = IPPROTO_COMP;
 193 out_ok:
 194         skb_push(skb, -skb_network_offset(skb));
 195         return 0;
 196 }
 197 EXPORT_SYMBOL_GPL(ipcomp_output);
 198
 199 static void ipcomp_free_scratches(void)
 200 {
 201         int i;
 202         void * __percpu *scratches;
 203
 204         if (--ipcomp_scratch_users)
 205                 return;
 206
 207         scratches = ipcomp_scratches;
 208         if (!scratches)
 209                 return;
 210
 211         for_each_possible_cpu(i)
 212                 vfree(*per_cpu_ptr(scratches, i));
 213
 214         free_percpu(scratches);
 215 }
 216
 217 static void * __percpu *ipcomp_alloc_scratches(void)
 218 {
 219         void * __percpu *scratches;
 220         int i;
 221
 222         if (ipcomp_scratch_users++)
 223                 return ipcomp_scratches;
 224
 225         scratches = alloc_percpu(void *);
 226         if (!scratches)
 227                 return NULL;
 228
 229         ipcomp_scratches = scratches;
 230
 231         for_each_possible_cpu(i) {
 232                 void *scratch;
 233
 234                 scratch = vmalloc_node(IPCOMP_SCRATCH_SIZE, cpu_to_node(i));
 235                 if (!scratch)
 236                         return NULL;
 237                 *per_cpu_ptr(scratches, i) = scratch;
 238         }
 239
 240         return scratches;
 241 }
 242
 243 static void ipcomp_free_tfms(struct crypto_comp * __percpu *tfms)
 244 {
 245         struct ipcomp_tfms *pos;
 246         int cpu;
 247
 248         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
 249                 if (pos->tfms == tfms)
 250                         break;
 251         }
 252
 253         WARN_ON(!pos);
 254
 255         if (--pos->users)
 256                 return;
 257
 258         list_del(&pos->list);
 259         kfree(pos);
 260
 261         if (!tfms)
 262                 return;
 263
 264         for_each_possible_cpu(cpu) {
 265                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
 266                 crypto_free_comp(tfm);
 267         }
 268         free_percpu(tfms);
 269 }
 270
 271 static struct crypto_comp * __percpu *ipcomp_alloc_tfms(const char *alg_name)
 272 {
 273         struct ipcomp_tfms *pos;
 274         struct crypto_comp * __percpu *tfms;
 275         int cpu;
 276
 277
 278         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
 279                 struct crypto_comp *tfm;
 280
 281                 /* This can be any valid CPU ID so we don't need locking. */
 282                 tfm = this_cpu_read(*pos->tfms);
 283
 284                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
 285                         pos->users++;
 286                         return pos->tfms;
 287                 }
 288         }
 289
 290         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 291         if (!pos)
 292                 return NULL;
 293
 294         pos->users = 1;
 295         INIT_LIST_HEAD(&pos->list);
 296         list_add(&pos->list, &ipcomp_tfms_list);
 297
 298         pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
 299         if (!tfms)
 300                 goto error;
 301
 302         for_each_possible_cpu(cpu) {
 303                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
 304                                                             CRYPTO_ALG_ASYNC);
 305                 if (IS_ERR(tfm))
 306                         goto error;
 307                 *per_cpu_ptr(tfms, cpu) = tfm;
 308         }
 309
 310         return tfms;
 311
 312 error:
 313         ipcomp_free_tfms(tfms);
 314         return NULL;
 315 }
 316
 317 static void ipcomp_free_data(struct ipcomp_data *ipcd)
 318 {
 319         if (ipcd->tfms)
 320                 ipcomp_free_tfms(ipcd->tfms);
 321         ipcomp_free_scratches();
 322 }
 323
 324 void ipcomp_destroy(struct xfrm_state *x)
 325 {
 326         struct ipcomp_data *ipcd = x->data;
 327         if (!ipcd)
 328                 return;
 329         xfrm_state_delete_tunnel(x);
 330         mutex_lock(&ipcomp_resource_mutex);
 331         ipcomp_free_data(ipcd);
 332         mutex_unlock(&ipcomp_resource_mutex);
 333         kfree(ipcd);
 334 }
 335 EXPORT_SYMBOL_GPL(ipcomp_destroy);
 336
 337 int ipcomp_init_state(struct xfrm_state *x)
 338 {
 339         int err;
 340         struct ipcomp_data *ipcd;
 341         struct xfrm_algo_desc *calg_desc;
 342
 343         err = -EINVAL;
 344         if (!x->calg)
 345                 goto out;
 346
 347         if (x->encap)
 348                 goto out;
 349
 350         err = -ENOMEM;
 351         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
 352         if (!ipcd)
 353                 goto out;
 354
 355         mutex_lock(&ipcomp_resource_mutex);
 356         if (!ipcomp_alloc_scratches())
 357                 goto error;
 358
 359         ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
 360         if (!ipcd->tfms)
 361                 goto error;
 362         mutex_unlock(&ipcomp_resource_mutex);
 363
 364         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
 365         BUG_ON(!calg_desc);
 366         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 367         x->data = ipcd;
 368         err = 0;
 369 out:
 370         return err;
 371
 372 error:
 373         ipcomp_free_data(ipcd);
 374         mutex_unlock(&ipcomp_resource_mutex);
 375         kfree(ipcd);
 376         goto out;
 377 }
 378 EXPORT_SYMBOL_GPL(ipcomp_init_state);
 379
 380 MODULE_LICENSE("GPL");
 381 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
 382 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");