net/dccp/ccid.c

   1 /*
   2  *  net/dccp/ccid.c
   3  *
   4  *  An implementation of the DCCP protocol
   5  *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   6  *
   7  *  CCID infrastructure
   8  *
   9  *      This program is free software; you can redistribute it and/or modify it
  10  *      under the terms of the GNU General Public License version 2 as
  11  *      published by the Free Software Foundation.
  12  */
  13
  14 #include "ccid.h"
  15
  16 static u8 builtin_ccids[] = {
  17         DCCPC_CCID2,            /* CCID2 is supported by default */
  18 #if defined(CONFIG_IP_DCCP_CCID3) || defined(CONFIG_IP_DCCP_CCID3_MODULE)
  19         DCCPC_CCID3,
  20 #endif
  21 };
  22
  23 static struct ccid_operations *ccids[CCID_MAX];
  24 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
  25 static atomic_t ccids_lockct = ATOMIC_INIT(0);
  26 static DEFINE_SPINLOCK(ccids_lock);
  27
  28 /*
  29  * The strategy is: modifications ccids vector are short, do not sleep and
  30  * veeery rare, but read access should be free of any exclusive locks.
  31  */
  32 static void ccids_write_lock(void)
  33 {
  34         spin_lock(&ccids_lock);
  35         while (atomic_read(&ccids_lockct) != 0) {
  36                 spin_unlock(&ccids_lock);
  37                 yield();
  38                 spin_lock(&ccids_lock);
  39         }
  40 }
  41
  42 static inline void ccids_write_unlock(void)
  43 {
  44         spin_unlock(&ccids_lock);
  45 }
  46
  47 static inline void ccids_read_lock(void)
  48 {
  49         atomic_inc(&ccids_lockct);
  50         smp_mb__after_atomic_inc();
  51         spin_unlock_wait(&ccids_lock);
  52 }
  53
  54 static inline void ccids_read_unlock(void)
  55 {
  56         atomic_dec(&ccids_lockct);
  57 }
  58
  59 #else
  60 #define ccids_write_lock() do { } while(0)
  61 #define ccids_write_unlock() do { } while(0)
  62 #define ccids_read_lock() do { } while(0)
  63 #define ccids_read_unlock() do { } while(0)
  64 #endif
  65
  66 static struct kmem_cache *ccid_kmem_cache_create(int obj_size, const char *fmt,...)
  67 {
  68         struct kmem_cache *slab;
  69         char slab_name_fmt[32], *slab_name;
  70         va_list args;
  71
  72         va_start(args, fmt);
  73         vsnprintf(slab_name_fmt, sizeof(slab_name_fmt), fmt, args);
  74         va_end(args);
  75
  76         slab_name = kstrdup(slab_name_fmt, GFP_KERNEL);
  77         if (slab_name == NULL)
  78                 return NULL;
  79         slab = kmem_cache_create(slab_name, sizeof(struct ccid) + obj_size, 0,
  80                                  SLAB_HWCACHE_ALIGN, NULL);
  81         if (slab == NULL)
  82                 kfree(slab_name);
  83         return slab;
  84 }
  85
  86 static void ccid_kmem_cache_destroy(struct kmem_cache *slab)
  87 {
  88         if (slab != NULL) {
  89                 const char *name = kmem_cache_name(slab);
  90
  91                 kmem_cache_destroy(slab);
  92                 kfree(name);
  93         }
  94 }
  95
  96 /* check that up to @array_len members in @ccid_array are supported */
  97 bool ccid_support_check(u8 const *ccid_array, u8 array_len)
  98 {
  99         u8 i, j, found;
 100
 101         for (i = 0, found = 0; i < array_len; i++, found = 0) {
 102                 for (j = 0; !found && j < ARRAY_SIZE(builtin_ccids); j++)
 103                         found = (ccid_array[i] == builtin_ccids[j]);
 104                 if (!found)
 105                         return false;
 106         }
 107         return true;
 108 }
 109
 110 /**
 111  * ccid_get_builtin_ccids  -  Provide copy of `builtin' CCID array
 112  * @ccid_array: pointer to copy into
 113  * @array_len: value to return length into
 114  * This function allocates memory - caller must see that it is freed after use.
 115  */
 116 int ccid_get_builtin_ccids(u8 **ccid_array, u8 *array_len)
 117 {
 118         *ccid_array = kmemdup(builtin_ccids, sizeof(builtin_ccids), gfp_any());
 119         if (*ccid_array == NULL)
 120                 return -ENOBUFS;
 121         *array_len = ARRAY_SIZE(builtin_ccids);
 122         return 0;
 123 }
 124
 125 int ccid_getsockopt_builtin_ccids(struct sock *sk, int len,
 126                                     char __user *optval, int __user *optlen)
 127 {
 128         if (len < sizeof(builtin_ccids))
 129                 return -EINVAL;
 130
 131         if (put_user(sizeof(builtin_ccids), optlen) ||
 132             copy_to_user(optval, builtin_ccids, sizeof(builtin_ccids)))
 133                 return -EFAULT;
 134         return 0;
 135 }
 136
 137 int ccid_register(struct ccid_operations *ccid_ops)
 138 {
 139         int err = -ENOBUFS;
 140
 141         ccid_ops->ccid_hc_rx_slab =
 142                         ccid_kmem_cache_create(ccid_ops->ccid_hc_rx_obj_size,
 143                                                "ccid%u_hc_rx_sock",
 144                                                ccid_ops->ccid_id);
 145         if (ccid_ops->ccid_hc_rx_slab == NULL)
 146                 goto out;
 147
 148         ccid_ops->ccid_hc_tx_slab =
 149                         ccid_kmem_cache_create(ccid_ops->ccid_hc_tx_obj_size,
 150                                                "ccid%u_hc_tx_sock",
 151                                                ccid_ops->ccid_id);
 152         if (ccid_ops->ccid_hc_tx_slab == NULL)
 153                 goto out_free_rx_slab;
 154
 155         ccids_write_lock();
 156         err = -EEXIST;
 157         if (ccids[ccid_ops->ccid_id] == NULL) {
 158                 ccids[ccid_ops->ccid_id] = ccid_ops;
 159                 err = 0;
 160         }
 161         ccids_write_unlock();
 162         if (err != 0)
 163                 goto out_free_tx_slab;
 164
 165         pr_info("CCID: Registered CCID %d (%s)\n",
 166                 ccid_ops->ccid_id, ccid_ops->ccid_name);
 167 out:
 168         return err;
 169 out_free_tx_slab:
 170         ccid_kmem_cache_destroy(ccid_ops->ccid_hc_tx_slab);
 171         ccid_ops->ccid_hc_tx_slab = NULL;
 172         goto out;
 173 out_free_rx_slab:
 174         ccid_kmem_cache_destroy(ccid_ops->ccid_hc_rx_slab);
 175         ccid_ops->ccid_hc_rx_slab = NULL;
 176         goto out;
 177 }
 178
 179 EXPORT_SYMBOL_GPL(ccid_register);
 180
 181 int ccid_unregister(struct ccid_operations *ccid_ops)
 182 {
 183         ccids_write_lock();
 184         ccids[ccid_ops->ccid_id] = NULL;
 185         ccids_write_unlock();
 186
 187         ccid_kmem_cache_destroy(ccid_ops->ccid_hc_tx_slab);
 188         ccid_ops->ccid_hc_tx_slab = NULL;
 189         ccid_kmem_cache_destroy(ccid_ops->ccid_hc_rx_slab);
 190         ccid_ops->ccid_hc_rx_slab = NULL;
 191
 192         pr_info("CCID: Unregistered CCID %d (%s)\n",
 193                 ccid_ops->ccid_id, ccid_ops->ccid_name);
 194         return 0;
 195 }
 196
 197 EXPORT_SYMBOL_GPL(ccid_unregister);
 198
 199 struct ccid *ccid_new(unsigned char id, struct sock *sk, int rx, gfp_t gfp)
 200 {
 201         struct ccid_operations *ccid_ops;
 202         struct ccid *ccid = NULL;
 203
 204         ccids_read_lock();
 205 #ifdef CONFIG_MODULES
 206         if (ccids[id] == NULL) {
 207                 /* We only try to load if in process context */
 208                 ccids_read_unlock();
 209                 if (gfp & GFP_ATOMIC)
 210                         goto out;
 211                 request_module("net-dccp-ccid-%d", id);
 212                 ccids_read_lock();
 213         }
 214 #endif
 215         ccid_ops = ccids[id];
 216         if (ccid_ops == NULL)
 217                 goto out_unlock;
 218
 219         if (!try_module_get(ccid_ops->ccid_owner))
 220                 goto out_unlock;
 221
 222         ccids_read_unlock();
 223
 224         ccid = kmem_cache_alloc(rx ? ccid_ops->ccid_hc_rx_slab :
 225                                      ccid_ops->ccid_hc_tx_slab, gfp);
 226         if (ccid == NULL)
 227                 goto out_module_put;
 228         ccid->ccid_ops = ccid_ops;
 229         if (rx) {
 230                 memset(ccid + 1, 0, ccid_ops->ccid_hc_rx_obj_size);
 231                 if (ccid->ccid_ops->ccid_hc_rx_init != NULL &&
 232                     ccid->ccid_ops->ccid_hc_rx_init(ccid, sk) != 0)
 233                         goto out_free_ccid;
 234         } else {
 235                 memset(ccid + 1, 0, ccid_ops->ccid_hc_tx_obj_size);
 236                 if (ccid->ccid_ops->ccid_hc_tx_init != NULL &&
 237                     ccid->ccid_ops->ccid_hc_tx_init(ccid, sk) != 0)
 238                         goto out_free_ccid;
 239         }
 240 out:
 241         return ccid;
 242 out_unlock:
 243         ccids_read_unlock();
 244         goto out;
 245 out_free_ccid:
 246         kmem_cache_free(rx ? ccid_ops->ccid_hc_rx_slab :
 247                         ccid_ops->ccid_hc_tx_slab, ccid);
 248         ccid = NULL;
 249 out_module_put:
 250         module_put(ccid_ops->ccid_owner);
 251         goto out;
 252 }
 253
 254 EXPORT_SYMBOL_GPL(ccid_new);
 255
 256 static void ccid_delete(struct ccid *ccid, struct sock *sk, int rx)
 257 {
 258         struct ccid_operations *ccid_ops;
 259
 260         if (ccid == NULL)
 261                 return;
 262
 263         ccid_ops = ccid->ccid_ops;
 264         if (rx) {
 265                 if (ccid_ops->ccid_hc_rx_exit != NULL)
 266                         ccid_ops->ccid_hc_rx_exit(sk);
 267                 kmem_cache_free(ccid_ops->ccid_hc_rx_slab,  ccid);
 268         } else {
 269                 if (ccid_ops->ccid_hc_tx_exit != NULL)
 270                         ccid_ops->ccid_hc_tx_exit(sk);
 271                 kmem_cache_free(ccid_ops->ccid_hc_tx_slab,  ccid);
 272         }
 273         ccids_read_lock();
 274         if (ccids[ccid_ops->ccid_id] != NULL)
 275                 module_put(ccid_ops->ccid_owner);
 276         ccids_read_unlock();
 277 }
 278
 279 void ccid_hc_rx_delete(struct ccid *ccid, struct sock *sk)
 280 {
 281         ccid_delete(ccid, sk, 1);
 282 }
 283
 284 EXPORT_SYMBOL_GPL(ccid_hc_rx_delete);
 285
 286 void ccid_hc_tx_delete(struct ccid *ccid, struct sock *sk)
 287 {
 288         ccid_delete(ccid, sk, 0);
 289 }
 290
 291 EXPORT_SYMBOL_GPL(ccid_hc_tx_delete);