net/core/iovec.c

   1 /*
   2  *      iovec manipulation routines.
   3  *
   4  *
   5  *              This program is free software; you can redistribute it and/or
   6  *              modify it under the terms of the GNU General Public License
   7  *              as published by the Free Software Foundation; either version
   8  *              2 of the License, or (at your option) any later version.
   9  *
  10  *      Fixes:
  11  *              Andrew Lunn     :       Errors in iovec copying.
  12  *              Pedro Roque     :       Added memcpy_fromiovecend and
  13  *                                      csum_..._fromiovecend.
  14  *              Andi Kleen      :       fixed error handling for 2.1
  15  *              Alexey Kuznetsov:       2.1 optimisations
  16  *              Andi Kleen      :       Fix csum*fromiovecend for IPv6.
  17  */
  18
  19 #include <linux/errno.h>
  20 #include <linux/module.h>
  21 #include <linux/kernel.h>
  22 #include <linux/mm.h>
  23 #include <linux/net.h>
  24 #include <linux/in6.h>
  25 #include <asm/uaccess.h>
  26 #include <asm/byteorder.h>
  27 #include <net/checksum.h>
  28 #include <net/sock.h>
  29
  30 /*
  31  *      Verify iovec. The caller must ensure that the iovec is big enough
  32  *      to hold the message iovec.
  33  *
  34  *      Save time not doing access_ok. copy_*_user will make this work
  35  *      in any case.
  36  */
  37
  38 int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr_storage *address, int mode)
  39 {
  40         int size, ct, err;
  41
  42         if (m->msg_namelen) {
  43                 if (mode == VERIFY_READ) {
  44                         void __user *namep;
  45                         namep = (void __user __force *) m->msg_name;
  46                         err = move_addr_to_kernel(namep, m->msg_namelen,
  47                                                   address);
  48                         if (err < 0)
  49                                 return err;
  50                 }
  51                 m->msg_name = address;
  52         } else {
  53                 m->msg_name = NULL;
  54         }
  55
  56         size = m->msg_iovlen * sizeof(struct iovec);
  57         if (copy_from_user(iov, (void __user __force *) m->msg_iov, size))
  58                 return -EFAULT;
  59
  60         m->msg_iov = iov;
  61         err = 0;
  62
  63         for (ct = 0; ct < m->msg_iovlen; ct++) {
  64                 size_t len = iov[ct].iov_len;
  65
  66                 if (len > INT_MAX - err) {
  67                         len = INT_MAX - err;
  68                         iov[ct].iov_len = len;
  69                 }
  70                 err += len;
  71         }
  72
  73         return err;
  74 }
  75
  76 /*
  77  *      Copy kernel to iovec. Returns -EFAULT on error.
  78  *
  79  *      Note: this modifies the original iovec.
  80  */
  81
  82 int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len)
  83 {
  84         while (len > 0) {
  85                 if (iov->iov_len) {
  86                         int copy = min_t(unsigned int, iov->iov_len, len);
  87                         if (copy_to_user(iov->iov_base, kdata, copy))
  88                                 return -EFAULT;
  89                         kdata += copy;
  90                         len -= copy;
  91                         iov->iov_len -= copy;
  92                         iov->iov_base += copy;
  93                 }
  94                 iov++;
  95         }
  96
  97         return 0;
  98 }
  99 EXPORT_SYMBOL(memcpy_toiovec);
 100
 101 /*
 102  *      Copy kernel to iovec. Returns -EFAULT on error.
 103  */
 104
 105 int memcpy_toiovecend(const struct iovec *iov, unsigned char *kdata,
 106                       int offset, int len)
 107 {
 108         int copy;
 109         for (; len > 0; ++iov) {
 110                 /* Skip over the finished iovecs */
 111                 if (unlikely(offset >= iov->iov_len)) {
 112                         offset -= iov->iov_len;
 113                         continue;
 114                 }
 115                 copy = min_t(unsigned int, iov->iov_len - offset, len);
 116                 if (copy_to_user(iov->iov_base + offset, kdata, copy))
 117                         return -EFAULT;
 118                 offset = 0;
 119                 kdata += copy;
 120                 len -= copy;
 121         }
 122
 123         return 0;
 124 }
 125 EXPORT_SYMBOL(memcpy_toiovecend);
 126
 127 /*
 128  *      Copy iovec to kernel. Returns -EFAULT on error.
 129  *
 130  *      Note: this modifies the original iovec.
 131  */
 132
 133 int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len)
 134 {
 135         while (len > 0) {
 136                 if (iov->iov_len) {
 137                         int copy = min_t(unsigned int, len, iov->iov_len);
 138                         if (copy_from_user(kdata, iov->iov_base, copy))
 139                                 return -EFAULT;
 140                         len -= copy;
 141                         kdata += copy;
 142                         iov->iov_base += copy;
 143                         iov->iov_len -= copy;
 144                 }
 145                 iov++;
 146         }
 147
 148         return 0;
 149 }
 150 EXPORT_SYMBOL(memcpy_fromiovec);
 151
 152 /*
 153  *      Copy iovec from kernel. Returns -EFAULT on error.
 154  */
 155
 156 int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
 157                         int offset, int len)
 158 {
 159         /* Skip over the finished iovecs */
 160         while (offset >= iov->iov_len) {
 161                 offset -= iov->iov_len;
 162                 iov++;
 163         }
 164
 165         while (len > 0) {
 166                 u8 __user *base = iov->iov_base + offset;
 167                 int copy = min_t(unsigned int, len, iov->iov_len - offset);
 168
 169                 offset = 0;
 170                 if (copy_from_user(kdata, base, copy))
 171                         return -EFAULT;
 172                 len -= copy;
 173                 kdata += copy;
 174                 iov++;
 175         }
 176
 177         return 0;
 178 }
 179 EXPORT_SYMBOL(memcpy_fromiovecend);
 180
 181 /*
 182  *      And now for the all-in-one: copy and checksum from a user iovec
 183  *      directly to a datagram
 184  *      Calls to csum_partial but the last must be in 32 bit chunks
 185  *
 186  *      ip_build_xmit must ensure that when fragmenting only the last
 187  *      call to this function will be unaligned also.
 188  */
 189 int csum_partial_copy_fromiovecend(unsigned char *kdata, struct iovec *iov,
 190                                  int offset, unsigned int len, __wsum *csump)
 191 {
 192         __wsum csum = *csump;
 193         int partial_cnt = 0, err = 0;
 194
 195         /* Skip over the finished iovecs */
 196         while (offset >= iov->iov_len) {
 197                 offset -= iov->iov_len;
 198                 iov++;
 199         }
 200
 201         while (len > 0) {
 202                 u8 __user *base = iov->iov_base + offset;
 203                 int copy = min_t(unsigned int, len, iov->iov_len - offset);
 204
 205                 offset = 0;
 206
 207                 /* There is a remnant from previous iov. */
 208                 if (partial_cnt) {
 209                         int par_len = 4 - partial_cnt;
 210
 211                         /* iov component is too short ... */
 212                         if (par_len > copy) {
 213                                 if (copy_from_user(kdata, base, copy))
 214                                         goto out_fault;
 215                                 kdata += copy;
 216                                 base += copy;
 217                                 partial_cnt += copy;
 218                                 len -= copy;
 219                                 iov++;
 220                                 if (len)
 221                                         continue;
 222                                 *csump = csum_partial(kdata - partial_cnt,
 223                                                          partial_cnt, csum);
 224                                 goto out;
 225                         }
 226                         if (copy_from_user(kdata, base, par_len))
 227                                 goto out_fault;
 228                         csum = csum_partial(kdata - partial_cnt, 4, csum);
 229                         kdata += par_len;
 230                         base  += par_len;
 231                         copy  -= par_len;
 232                         len   -= par_len;
 233                         partial_cnt = 0;
 234                 }
 235
 236                 if (len > copy) {
 237                         partial_cnt = copy % 4;
 238                         if (partial_cnt) {
 239                                 copy -= partial_cnt;
 240                                 if (copy_from_user(kdata + copy, base + copy,
 241                                                 partial_cnt))
 242                                         goto out_fault;
 243                         }
 244                 }
 245
 246                 if (copy) {
 247                         csum = csum_and_copy_from_user(base, kdata, copy,
 248                                                         csum, &err);
 249                         if (err)
 250                                 goto out;
 251                 }
 252                 len   -= copy + partial_cnt;
 253                 kdata += copy + partial_cnt;
 254                 iov++;
 255         }
 256         *csump = csum;
 257 out:
 258         return err;
 259
 260 out_fault:
 261         err = -EFAULT;
 262         goto out;
 263 }
 264 EXPORT_SYMBOL(csum_partial_copy_fromiovecend);