include/linux/uio.h

   1 /*
   2  *      Berkeley style UIO structures   -       Alan Cox 1994.
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  */
   9 #ifndef __LINUX_UIO_H
  10 #define __LINUX_UIO_H
  11
  12 #include <linux/kernel.h>
  13 #include <linux/thread_info.h>
  14 #include <uapi/linux/uio.h>
  15
  16 struct page;
  17 struct pipe_inode_info;
  18
  19 struct kvec {
  20         void *iov_base; /* and that should *never* hold a userland pointer */
  21         size_t iov_len;
  22 };
  23
  24 enum {
  25         ITER_IOVEC = 0,
  26         ITER_KVEC = 2,
  27         ITER_BVEC = 4,
  28         ITER_PIPE = 8,
  29 };
  30
  31 struct iov_iter {
  32         int type;
  33         size_t iov_offset;
  34         size_t count;
  35         union {
  36                 const struct iovec *iov;
  37                 const struct kvec *kvec;
  38                 const struct bio_vec *bvec;
  39                 struct pipe_inode_info *pipe;
  40         };
  41         union {
  42                 unsigned long nr_segs;
  43                 struct {
  44                         int idx;
  45                         int start_idx;
  46                 };
  47         };
  48 };
  49
  50 /*
  51  * Total number of bytes covered by an iovec.
  52  *
  53  * NOTE that it is not safe to use this function until all the iovec's
  54  * segment lengths have been validated.  Because the individual lengths can
  55  * overflow a size_t when added together.
  56  */
  57 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
  58 {
  59         unsigned long seg;
  60         size_t ret = 0;
  61
  62         for (seg = 0; seg < nr_segs; seg++)
  63                 ret += iov[seg].iov_len;
  64         return ret;
  65 }
  66
  67 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
  68 {
  69         return (struct iovec) {
  70                 .iov_base = iter->iov->iov_base + iter->iov_offset,
  71                 .iov_len = min(iter->count,
  72                                iter->iov->iov_len - iter->iov_offset),
  73         };
  74 }
  75
  76 #define iov_for_each(iov, iter, start)                          \
  77         if (!((start).type & (ITER_BVEC | ITER_PIPE)))          \
  78         for (iter = (start);                                    \
  79              (iter).count &&                                    \
  80              ((iov = iov_iter_iovec(&(iter))), 1);              \
  81              iov_iter_advance(&(iter), (iov).iov_len))
  82
  83 size_t iov_iter_copy_from_user_atomic(struct page *page,
  84                 struct iov_iter *i, unsigned long offset, size_t bytes);
  85 void iov_iter_advance(struct iov_iter *i, size_t bytes);
  86 void iov_iter_revert(struct iov_iter *i, size_t bytes);
  87 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
  88 size_t iov_iter_single_seg_count(const struct iov_iter *i);
  89 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
  90                          struct iov_iter *i);
  91 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
  92                          struct iov_iter *i);
  93
  94 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
  95 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
  96 bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i);
  97 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
  98 bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i);
  99
 100 static __always_inline __must_check
 101 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
 102 {
 103         if (unlikely(!check_copy_size(addr, bytes, true)))
 104                 return 0;
 105         else
 106                 return _copy_to_iter(addr, bytes, i);
 107 }
 108
 109 static __always_inline __must_check
 110 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
 111 {
 112         if (unlikely(!check_copy_size(addr, bytes, false)))
 113                 return 0;
 114         else
 115                 return _copy_from_iter(addr, bytes, i);
 116 }
 117
 118 static __always_inline __must_check
 119 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
 120 {
 121         if (unlikely(!check_copy_size(addr, bytes, false)))
 122                 return false;
 123         else
 124                 return _copy_from_iter_full(addr, bytes, i);
 125 }
 126
 127 static __always_inline __must_check
 128 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
 129 {
 130         if (unlikely(!check_copy_size(addr, bytes, false)))
 131                 return 0;
 132         else
 133                 return _copy_from_iter_nocache(addr, bytes, i);
 134 }
 135
 136 static __always_inline __must_check
 137 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
 138 {
 139         if (unlikely(!check_copy_size(addr, bytes, false)))
 140                 return false;
 141         else
 142                 return _copy_from_iter_full_nocache(addr, bytes, i);
 143 }
 144
 145 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
 146 /*
 147  * Note, users like pmem that depend on the stricter semantics of
 148  * copy_from_iter_flushcache() than copy_from_iter_nocache() must check for
 149  * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
 150  * destination is flushed from the cache on return.
 151  */
 152 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
 153 #else
 154 #define _copy_from_iter_flushcache _copy_from_iter_nocache
 155 #endif
 156
 157 #ifdef CONFIG_ARCH_HAS_UACCESS_MCSAFE
 158 size_t _copy_to_iter_mcsafe(const void *addr, size_t bytes, struct iov_iter *i);
 159 #else
 160 #define _copy_to_iter_mcsafe _copy_to_iter
 161 #endif
 162
 163 static __always_inline __must_check
 164 size_t copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
 165 {
 166         if (unlikely(!check_copy_size(addr, bytes, false)))
 167                 return 0;
 168         else
 169                 return _copy_from_iter_flushcache(addr, bytes, i);
 170 }
 171
 172 static __always_inline __must_check
 173 size_t copy_to_iter_mcsafe(void *addr, size_t bytes, struct iov_iter *i)
 174 {
 175         if (unlikely(!check_copy_size(addr, bytes, true)))
 176                 return 0;
 177         else
 178                 return _copy_to_iter_mcsafe(addr, bytes, i);
 179 }
 180
 181 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
 182 unsigned long iov_iter_alignment(const struct iov_iter *i);
 183 unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
 184 void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
 185                         unsigned long nr_segs, size_t count);
 186 void iov_iter_kvec(struct iov_iter *i, int direction, const struct kvec *kvec,
 187                         unsigned long nr_segs, size_t count);
 188 void iov_iter_bvec(struct iov_iter *i, int direction, const struct bio_vec *bvec,
 189                         unsigned long nr_segs, size_t count);
 190 void iov_iter_pipe(struct iov_iter *i, int direction, struct pipe_inode_info *pipe,
 191                         size_t count);
 192 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
 193                         size_t maxsize, unsigned maxpages, size_t *start);
 194 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
 195                         size_t maxsize, size_t *start);
 196 int iov_iter_npages(const struct iov_iter *i, int maxpages);
 197
 198 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
 199
 200 static inline size_t iov_iter_count(const struct iov_iter *i)
 201 {
 202         return i->count;
 203 }
 204
 205 static inline bool iter_is_iovec(const struct iov_iter *i)
 206 {
 207         return !(i->type & (ITER_BVEC | ITER_KVEC | ITER_PIPE));
 208 }
 209
 210 /*
 211  * Get one of READ or WRITE out of iter->type without any other flags OR'd in
 212  * with it.
 213  *
 214  * The ?: is just for type safety.
 215  */
 216 #define iov_iter_rw(i) ((0 ? (struct iov_iter *)0 : (i))->type & (READ | WRITE))
 217
 218 /*
 219  * Cap the iov_iter by given limit; note that the second argument is
 220  * *not* the new size - it's upper limit for such.  Passing it a value
 221  * greater than the amount of data in iov_iter is fine - it'll just do
 222  * nothing in that case.
 223  */
 224 static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
 225 {
 226         /*
 227          * count doesn't have to fit in size_t - comparison extends both
 228          * operands to u64 here and any value that would be truncated by
 229          * conversion in assignement is by definition greater than all
 230          * values of size_t, including old i->count.
 231          */
 232         if (i->count > count)
 233                 i->count = count;
 234 }
 235
 236 /*
 237  * reexpand a previously truncated iterator; count must be no more than how much
 238  * we had shrunk it.
 239  */
 240 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
 241 {
 242         i->count = count;
 243 }
 244 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 245 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 246 bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 247
 248 int import_iovec(int type, const struct iovec __user * uvector,
 249                  unsigned nr_segs, unsigned fast_segs,
 250                  struct iovec **iov, struct iov_iter *i);
 251
 252 #ifdef CONFIG_COMPAT
 253 struct compat_iovec;
 254 int compat_import_iovec(int type, const struct compat_iovec __user * uvector,
 255                  unsigned nr_segs, unsigned fast_segs,
 256                  struct iovec **iov, struct iov_iter *i);
 257 #endif
 258
 259 int import_single_range(int type, void __user *buf, size_t len,
 260                  struct iovec *iov, struct iov_iter *i);
 261
 262 int iov_iter_for_each_range(struct iov_iter *i, size_t bytes,
 263                             int (*f)(struct kvec *vec, void *context),
 264                             void *context);
 265
 266 #endif