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