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/slab.h>
  24 #include <linux/net.h>
  25 #include <linux/in6.h>
  26 #include <asm/uaccess.h>
  27 #include <asm/byteorder.h>
  28 #include <net/checksum.h>
  29 #include <net/sock.h>
  30
  31 /*
  32  *      Verify iovec. The caller must ensure that the iovec is big enough
  33  *      to hold the message iovec.
  34  *
  35  *      Save time not doing access_ok. copy_*_user will make this work
  36  *      in any case.
  37  */
  38
  39 int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr *address, int mode)
  40 {
  41         int size, err, ct;
  42
  43         if (m->msg_namelen) {
  44                 if (mode == VERIFY_READ) {
  45                         err = move_addr_to_kernel(m->msg_name, m->msg_namelen,
  46                                                   address);
  47                         if (err < 0)
  48                                 return err;
  49                 }
  50                 m->msg_name = address;
  51         } else {
  52                 m->msg_name = NULL;
  53         }
  54
  55         size = m->msg_iovlen * sizeof(struct iovec);
  56         if (copy_from_user(iov, m->msg_iov, size))
  57                 return -EFAULT;
  58
  59         m->msg_iov = iov;
  60         err = 0;
  61
  62         for (ct = 0; ct < m->msg_iovlen; ct++) {
  63                 err += iov[ct].iov_len;
  64                 /*
  65                  * Goal is not to verify user data, but to prevent returning
  66                  * negative value, which is interpreted as errno.
  67                  * Overflow is still possible, but it is harmless.
  68                  */
  69                 if (err < 0)
  70                         return -EMSGSIZE;
  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
 100 /*
 101  *      Copy kernel to iovec. Returns -EFAULT on error.
 102  */
 103
 104 int memcpy_toiovecend(const struct iovec *iov, unsigned char *kdata,
 105                       int offset, int len)
 106 {
 107         int copy;
 108         for (; len > 0; ++iov) {
 109                 /* Skip over the finished iovecs */
 110                 if (unlikely(offset >= iov->iov_len)) {
 111                         offset -= iov->iov_len;
 112                         continue;
 113                 }
 114                 copy = min_t(unsigned int, iov->iov_len - offset, len);
 115                 if (copy_to_user(iov->iov_base + offset, kdata, copy))
 116                         return -EFAULT;
 117                 offset = 0;
 118                 kdata += copy;
 119                 len -= copy;
 120         }
 121
 122         return 0;
 123 }
 124
 125 /*
 126  *      Copy iovec to kernel. Returns -EFAULT on error.
 127  *
 128  *      Note: this modifies the original iovec.
 129  */
 130
 131 int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len)
 132 {
 133         while (len > 0) {
 134                 if (iov->iov_len) {
 135                         int copy = min_t(unsigned int, len, iov->iov_len);
 136                         if (copy_from_user(kdata, iov->iov_base, copy))
 137                                 return -EFAULT;
 138                         len -= copy;
 139                         kdata += copy;
 140                         iov->iov_base += copy;
 141                         iov->iov_len -= copy;
 142                 }
 143                 iov++;
 144         }
 145
 146         return 0;
 147 }
 148
 149 /*
 150  *      Copy iovec from kernel. Returns -EFAULT on error.
 151  */
 152
 153 int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
 154                         int offset, int len)
 155 {
 156         /* Skip over the finished iovecs */
 157         while (offset >= iov->iov_len) {
 158                 offset -= iov->iov_len;
 159                 iov++;
 160         }
 161
 162         while (len > 0) {
 163                 u8 __user *base = iov->iov_base + offset;
 164                 int copy = min_t(unsigned int, len, iov->iov_len - offset);
 165
 166                 offset = 0;
 167                 if (copy_from_user(kdata, base, copy))
 168                         return -EFAULT;
 169                 len -= copy;
 170                 kdata += copy;
 171                 iov++;
 172         }
 173
 174         return 0;
 175 }
 176
 177 /*
 178  *      And now for the all-in-one: copy and checksum from a user iovec
 179  *      directly to a datagram
 180  *      Calls to csum_partial but the last must be in 32 bit chunks
 181  *
 182  *      ip_build_xmit must ensure that when fragmenting only the last
 183  *      call to this function will be unaligned also.
 184  */
 185 int csum_partial_copy_fromiovecend(unsigned char *kdata, struct iovec *iov,
 186                                  int offset, unsigned int len, __wsum *csump)
 187 {
 188         __wsum csum = *csump;
 189         int partial_cnt = 0, err = 0;
 190
 191         /* Skip over the finished iovecs */
 192         while (offset >= iov->iov_len) {
 193                 offset -= iov->iov_len;
 194                 iov++;
 195         }
 196
 197         while (len > 0) {
 198                 u8 __user *base = iov->iov_base + offset;
 199                 int copy = min_t(unsigned int, len, iov->iov_len - offset);
 200
 201                 offset = 0;
 202
 203                 /* There is a remnant from previous iov. */
 204                 if (partial_cnt) {
 205                         int par_len = 4 - partial_cnt;
 206
 207                         /* iov component is too short ... */
 208                         if (par_len > copy) {
 209                                 if (copy_from_user(kdata, base, copy))
 210                                         goto out_fault;
 211                                 kdata += copy;
 212                                 base += copy;
 213                                 partial_cnt += copy;
 214                                 len -= copy;
 215                                 iov++;
 216                                 if (len)
 217                                         continue;
 218                                 *csump = csum_partial(kdata - partial_cnt,
 219                                                          partial_cnt, csum);
 220                                 goto out;
 221                         }
 222                         if (copy_from_user(kdata, base, par_len))
 223                                 goto out_fault;
 224                         csum = csum_partial(kdata - partial_cnt, 4, csum);
 225                         kdata += par_len;
 226                         base  += par_len;
 227                         copy  -= par_len;
 228                         len   -= par_len;
 229                         partial_cnt = 0;
 230                 }
 231
 232                 if (len > copy) {
 233                         partial_cnt = copy % 4;
 234                         if (partial_cnt) {
 235                                 copy -= partial_cnt;
 236                                 if (copy_from_user(kdata + copy, base + copy,
 237                                                 partial_cnt))
 238                                         goto out_fault;
 239                         }
 240                 }
 241
 242                 if (copy) {
 243                         csum = csum_and_copy_from_user(base, kdata, copy,
 244                                                         csum, &err);
 245                         if (err)
 246                                 goto out;
 247                 }
 248                 len   -= copy + partial_cnt;
 249                 kdata += copy + partial_cnt;
 250                 iov++;
 251         }
 252         *csump = csum;
 253 out:
 254         return err;
 255
 256 out_fault:
 257         err = -EFAULT;
 258         goto out;
 259 }
 260
 261 EXPORT_SYMBOL(csum_partial_copy_fromiovecend);
 262 EXPORT_SYMBOL(memcpy_fromiovec);
 263 EXPORT_SYMBOL(memcpy_fromiovecend);
 264 EXPORT_SYMBOL(memcpy_toiovec);
 265 EXPORT_SYMBOL(memcpy_toiovecend);