net/core/utils.c

   1 /*
   2  *      Generic address resultion entity
   3  *
   4  *      Authors:
   5  *      net_random Alan Cox
   6  *      net_ratelimit Andi Kleen
   7  *      in{4,6}_pton YOSHIFUJI Hideaki, Copyright (C)2006 USAGI/WIDE Project
   8  *
   9  *      Created by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
  10  *
  11  *      This program is free software; you can redistribute it and/or
  12  *      modify it under the terms of the GNU General Public License
  13  *      as published by the Free Software Foundation; either version
  14  *      2 of the License, or (at your option) any later version.
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/jiffies.h>
  19 #include <linux/kernel.h>
  20 #include <linux/ctype.h>
  21 #include <linux/inet.h>
  22 #include <linux/mm.h>
  23 #include <linux/net.h>
  24 #include <linux/string.h>
  25 #include <linux/types.h>
  26 #include <linux/percpu.h>
  27 #include <linux/init.h>
  28 #include <linux/ratelimit.h>
  29
  30 #include <net/sock.h>
  31 #include <net/net_ratelimit.h>
  32
  33 #include <asm/byteorder.h>
  34 #include <asm/uaccess.h>
  35
  36 int net_msg_warn __read_mostly = 1;
  37 EXPORT_SYMBOL(net_msg_warn);
  38
  39 DEFINE_RATELIMIT_STATE(net_ratelimit_state, 5 * HZ, 10);
  40 /*
  41  * All net warning printk()s should be guarded by this function.
  42  */
  43 int net_ratelimit(void)
  44 {
  45         return __ratelimit(&net_ratelimit_state);
  46 }
  47 EXPORT_SYMBOL(net_ratelimit);
  48
  49 /*
  50  * Convert an ASCII string to binary IP.
  51  * This is outside of net/ipv4/ because various code that uses IP addresses
  52  * is otherwise not dependent on the TCP/IP stack.
  53  */
  54
  55 __be32 in_aton(const char *str)
  56 {
  57         unsigned long l;
  58         unsigned int val;
  59         int i;
  60
  61         l = 0;
  62         for (i = 0; i < 4; i++) {
  63                 l <<= 8;
  64                 if (*str != '\0') {
  65                         val = 0;
  66                         while (*str != '\0' && *str != '.' && *str != '\n') {
  67                                 val *= 10;
  68                                 val += *str - '0';
  69                                 str++;
  70                         }
  71                         l |= val;
  72                         if (*str != '\0')
  73                                 str++;
  74                 }
  75         }
  76         return htonl(l);
  77 }
  78 EXPORT_SYMBOL(in_aton);
  79
  80 #define IN6PTON_XDIGIT          0x00010000
  81 #define IN6PTON_DIGIT           0x00020000
  82 #define IN6PTON_COLON_MASK      0x00700000
  83 #define IN6PTON_COLON_1         0x00100000      /* single : requested */
  84 #define IN6PTON_COLON_2         0x00200000      /* second : requested */
  85 #define IN6PTON_COLON_1_2       0x00400000      /* :: requested */
  86 #define IN6PTON_DOT             0x00800000      /* . */
  87 #define IN6PTON_DELIM           0x10000000
  88 #define IN6PTON_NULL            0x20000000      /* first/tail */
  89 #define IN6PTON_UNKNOWN         0x40000000
  90
  91 static inline int xdigit2bin(char c, int delim)
  92 {
  93         int val;
  94
  95         if (c == delim || c == '\0')
  96                 return IN6PTON_DELIM;
  97         if (c == ':')
  98                 return IN6PTON_COLON_MASK;
  99         if (c == '.')
 100                 return IN6PTON_DOT;
 101
 102         val = hex_to_bin(c);
 103         if (val >= 0)
 104                 return val | IN6PTON_XDIGIT | (val < 10 ? IN6PTON_DIGIT : 0);
 105
 106         if (delim == -1)
 107                 return IN6PTON_DELIM;
 108         return IN6PTON_UNKNOWN;
 109 }
 110
 111 /**
 112  * in4_pton - convert an IPv4 address from literal to binary representation
 113  * @src: the start of the IPv4 address string
 114  * @srclen: the length of the string, -1 means strlen(src)
 115  * @dst: the binary (u8[4] array) representation of the IPv4 address
 116  * @delim: the delimiter of the IPv4 address in @src, -1 means no delimiter
 117  * @end: A pointer to the end of the parsed string will be placed here
 118  *
 119  * Return one on success, return zero when any error occurs
 120  * and @end will point to the end of the parsed string.
 121  *
 122  */
 123 int in4_pton(const char *src, int srclen,
 124              u8 *dst,
 125              int delim, const char **end)
 126 {
 127         const char *s;
 128         u8 *d;
 129         u8 dbuf[4];
 130         int ret = 0;
 131         int i;
 132         int w = 0;
 133
 134         if (srclen < 0)
 135                 srclen = strlen(src);
 136         s = src;
 137         d = dbuf;
 138         i = 0;
 139         while(1) {
 140                 int c;
 141                 c = xdigit2bin(srclen > 0 ? *s : '\0', delim);
 142                 if (!(c & (IN6PTON_DIGIT | IN6PTON_DOT | IN6PTON_DELIM | IN6PTON_COLON_MASK))) {
 143                         goto out;
 144                 }
 145                 if (c & (IN6PTON_DOT | IN6PTON_DELIM | IN6PTON_COLON_MASK)) {
 146                         if (w == 0)
 147                                 goto out;
 148                         *d++ = w & 0xff;
 149                         w = 0;
 150                         i++;
 151                         if (c & (IN6PTON_DELIM | IN6PTON_COLON_MASK)) {
 152                                 if (i != 4)
 153                                         goto out;
 154                                 break;
 155                         }
 156                         goto cont;
 157                 }
 158                 w = (w * 10) + c;
 159                 if ((w & 0xffff) > 255) {
 160                         goto out;
 161                 }
 162 cont:
 163                 if (i >= 4)
 164                         goto out;
 165                 s++;
 166                 srclen--;
 167         }
 168         ret = 1;
 169         memcpy(dst, dbuf, sizeof(dbuf));
 170 out:
 171         if (end)
 172                 *end = s;
 173         return ret;
 174 }
 175 EXPORT_SYMBOL(in4_pton);
 176
 177 /**
 178  * in6_pton - convert an IPv6 address from literal to binary representation
 179  * @src: the start of the IPv6 address string
 180  * @srclen: the length of the string, -1 means strlen(src)
 181  * @dst: the binary (u8[16] array) representation of the IPv6 address
 182  * @delim: the delimiter of the IPv6 address in @src, -1 means no delimiter
 183  * @end: A pointer to the end of the parsed string will be placed here
 184  *
 185  * Return one on success, return zero when any error occurs
 186  * and @end will point to the end of the parsed string.
 187  *
 188  */
 189 int in6_pton(const char *src, int srclen,
 190              u8 *dst,
 191              int delim, const char **end)
 192 {
 193         const char *s, *tok = NULL;
 194         u8 *d, *dc = NULL;
 195         u8 dbuf[16];
 196         int ret = 0;
 197         int i;
 198         int state = IN6PTON_COLON_1_2 | IN6PTON_XDIGIT | IN6PTON_NULL;
 199         int w = 0;
 200
 201         memset(dbuf, 0, sizeof(dbuf));
 202
 203         s = src;
 204         d = dbuf;
 205         if (srclen < 0)
 206                 srclen = strlen(src);
 207
 208         while (1) {
 209                 int c;
 210
 211                 c = xdigit2bin(srclen > 0 ? *s : '\0', delim);
 212                 if (!(c & state))
 213                         goto out;
 214                 if (c & (IN6PTON_DELIM | IN6PTON_COLON_MASK)) {
 215                         /* process one 16-bit word */
 216                         if (!(state & IN6PTON_NULL)) {
 217                                 *d++ = (w >> 8) & 0xff;
 218                                 *d++ = w & 0xff;
 219                         }
 220                         w = 0;
 221                         if (c & IN6PTON_DELIM) {
 222                                 /* We've processed last word */
 223                                 break;
 224                         }
 225                         /*
 226                          * COLON_1 => XDIGIT
 227                          * COLON_2 => XDIGIT|DELIM
 228                          * COLON_1_2 => COLON_2
 229                          */
 230                         switch (state & IN6PTON_COLON_MASK) {
 231                         case IN6PTON_COLON_2:
 232                                 dc = d;
 233                                 state = IN6PTON_XDIGIT | IN6PTON_DELIM;
 234                                 if (dc - dbuf >= sizeof(dbuf))
 235                                         state |= IN6PTON_NULL;
 236                                 break;
 237                         case IN6PTON_COLON_1|IN6PTON_COLON_1_2:
 238                                 state = IN6PTON_XDIGIT | IN6PTON_COLON_2;
 239                                 break;
 240                         case IN6PTON_COLON_1:
 241                                 state = IN6PTON_XDIGIT;
 242                                 break;
 243                         case IN6PTON_COLON_1_2:
 244                                 state = IN6PTON_COLON_2;
 245                                 break;
 246                         default:
 247                                 state = 0;
 248                         }
 249                         tok = s + 1;
 250                         goto cont;
 251                 }
 252
 253                 if (c & IN6PTON_DOT) {
 254                         ret = in4_pton(tok ? tok : s, srclen + (int)(s - tok), d, delim, &s);
 255                         if (ret > 0) {
 256                                 d += 4;
 257                                 break;
 258                         }
 259                         goto out;
 260                 }
 261
 262                 w = (w << 4) | (0xff & c);
 263                 state = IN6PTON_COLON_1 | IN6PTON_DELIM;
 264                 if (!(w & 0xf000)) {
 265                         state |= IN6PTON_XDIGIT;
 266                 }
 267                 if (!dc && d + 2 < dbuf + sizeof(dbuf)) {
 268                         state |= IN6PTON_COLON_1_2;
 269                         state &= ~IN6PTON_DELIM;
 270                 }
 271                 if (d + 2 >= dbuf + sizeof(dbuf)) {
 272                         state &= ~(IN6PTON_COLON_1|IN6PTON_COLON_1_2);
 273                 }
 274 cont:
 275                 if ((dc && d + 4 < dbuf + sizeof(dbuf)) ||
 276                     d + 4 == dbuf + sizeof(dbuf)) {
 277                         state |= IN6PTON_DOT;
 278                 }
 279                 if (d >= dbuf + sizeof(dbuf)) {
 280                         state &= ~(IN6PTON_XDIGIT|IN6PTON_COLON_MASK);
 281                 }
 282                 s++;
 283                 srclen--;
 284         }
 285
 286         i = 15; d--;
 287
 288         if (dc) {
 289                 while(d >= dc)
 290                         dst[i--] = *d--;
 291                 while(i >= dc - dbuf)
 292                         dst[i--] = 0;
 293                 while(i >= 0)
 294                         dst[i--] = *d--;
 295         } else
 296                 memcpy(dst, dbuf, sizeof(dbuf));
 297
 298         ret = 1;
 299 out:
 300         if (end)
 301                 *end = s;
 302         return ret;
 303 }
 304 EXPORT_SYMBOL(in6_pton);
 305
 306 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
 307                               __be32 from, __be32 to, int pseudohdr)
 308 {
 309         __be32 diff[] = { ~from, to };
 310         if (skb->ip_summed != CHECKSUM_PARTIAL) {
 311                 *sum = csum_fold(csum_partial(diff, sizeof(diff),
 312                                 ~csum_unfold(*sum)));
 313                 if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
 314                         skb->csum = ~csum_partial(diff, sizeof(diff),
 315                                                 ~skb->csum);
 316         } else if (pseudohdr)
 317                 *sum = ~csum_fold(csum_partial(diff, sizeof(diff),
 318                                 csum_unfold(*sum)));
 319 }
 320 EXPORT_SYMBOL(inet_proto_csum_replace4);
 321
 322 void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
 323                                const __be32 *from, const __be32 *to,
 324                                int pseudohdr)
 325 {
 326         __be32 diff[] = {
 327                 ~from[0], ~from[1], ~from[2], ~from[3],
 328                 to[0], to[1], to[2], to[3],
 329         };
 330         if (skb->ip_summed != CHECKSUM_PARTIAL) {
 331                 *sum = csum_fold(csum_partial(diff, sizeof(diff),
 332                                  ~csum_unfold(*sum)));
 333                 if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
 334                         skb->csum = ~csum_partial(diff, sizeof(diff),
 335                                                   ~skb->csum);
 336         } else if (pseudohdr)
 337                 *sum = ~csum_fold(csum_partial(diff, sizeof(diff),
 338                                   csum_unfold(*sum)));
 339 }
 340 EXPORT_SYMBOL(inet_proto_csum_replace16);
 341
 342 struct __net_random_once_work {
 343         struct work_struct work;
 344         struct static_key *key;
 345 };
 346
 347 static void __net_random_once_deferred(struct work_struct *w)
 348 {
 349         struct __net_random_once_work *work =
 350                 container_of(w, struct __net_random_once_work, work);
 351         BUG_ON(!static_key_enabled(work->key));
 352         static_key_slow_dec(work->key);
 353         kfree(work);
 354 }
 355
 356 static void __net_random_once_disable_jump(struct static_key *key)
 357 {
 358         struct __net_random_once_work *w;
 359
 360         w = kmalloc(sizeof(*w), GFP_ATOMIC);
 361         if (!w)
 362                 return;
 363
 364         INIT_WORK(&w->work, __net_random_once_deferred);
 365         w->key = key;
 366         schedule_work(&w->work);
 367 }
 368
 369 bool __net_get_random_once(void *buf, int nbytes, bool *done,
 370                            struct static_key *once_key)
 371 {
 372         static DEFINE_SPINLOCK(lock);
 373         unsigned long flags;
 374
 375         spin_lock_irqsave(&lock, flags);
 376         if (*done) {
 377                 spin_unlock_irqrestore(&lock, flags);
 378                 return false;
 379         }
 380
 381         get_random_bytes(buf, nbytes);
 382         *done = true;
 383         spin_unlock_irqrestore(&lock, flags);
 384
 385         __net_random_once_disable_jump(once_key);
 386
 387         return true;
 388 }
 389 EXPORT_SYMBOL(__net_get_random_once);