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 iter_type {
  25         ITER_IOVEC = 0,
  26         ITER_KVEC = 2,
  27         ITER_BVEC = 4,
  28         ITER_PIPE = 8,
  29         ITER_DISCARD = 16,
  30 };
  31
  32 struct iov_iter {
  33         unsigned int type;
  34         size_t iov_offset;
  35         size_t count;
  36         union {
  37                 const struct iovec *iov;
  38                 const struct kvec *kvec;
  39                 const struct bio_vec *bvec;
  40                 struct pipe_inode_info *pipe;
  41         };
  42         union {
  43                 unsigned long nr_segs;
  44                 struct {
  45                         int idx;
  46                         int start_idx;
  47                 };
  48         };
  49 };
  50
  51 static inline enum iter_type iov_iter_type(const struct iov_iter *i)
  52 {
  53         return i->type & ~(READ | WRITE);
  54 }
  55
  56 static inline bool iter_is_iovec(const struct iov_iter *i)
  57 {
  58         return iov_iter_type(i) == ITER_IOVEC;
  59 }
  60
  61 static inline bool iov_iter_is_kvec(const struct iov_iter *i)
  62 {
  63         return iov_iter_type(i) == ITER_KVEC;
  64 }
  65
  66 static inline bool iov_iter_is_bvec(const struct iov_iter *i)
  67 {
  68         return iov_iter_type(i) == ITER_BVEC;
  69 }
  70
  71 static inline bool iov_iter_is_pipe(const struct iov_iter *i)
  72 {
  73         return iov_iter_type(i) == ITER_PIPE;
  74 }
  75
  76 static inline bool iov_iter_is_discard(const struct iov_iter *i)
  77 {
  78         return iov_iter_type(i) == ITER_DISCARD;
  79 }
  80
  81 static inline unsigned char iov_iter_rw(const struct iov_iter *i)
  82 {
  83         return i->type & (READ | WRITE);
  84 }
  85
  86 /*
  87  * Total number of bytes covered by an iovec.
  88  *
  89  * NOTE that it is not safe to use this function until all the iovec's
  90  * segment lengths have been validated.  Because the individual lengths can
  91  * overflow a size_t when added together.
  92  */
  93 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
  94 {
  95         unsigned long seg;
  96         size_t ret = 0;
  97
  98         for (seg = 0; seg < nr_segs; seg++)
  99                 ret += iov[seg].iov_len;
 100         return ret;
 101 }
 102
 103 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
 104 {
 105         return (struct iovec) {
 106                 .iov_base = iter->iov->iov_base + iter->iov_offset,
 107                 .iov_len = min(iter->count,
 108                                iter->iov->iov_len - iter->iov_offset),
 109         };
 110 }
 111
 112 #define iov_for_each(iov, iter, start)                          \
 113         if (iov_iter_type(start) == ITER_IOVEC ||               \
 114             iov_iter_type(start) == ITER_KVEC)                  \
 115         for (iter = (start);                                    \
 116              (iter).count &&                                    \
 117              ((iov = iov_iter_iovec(&(iter))), 1);              \
 118              iov_iter_advance(&(iter), (iov).iov_len))
 119
 120 size_t iov_iter_copy_from_user_atomic(struct page *page,
 121                 struct iov_iter *i, unsigned long offset, size_t bytes);
 122 void iov_iter_advance(struct iov_iter *i, size_t bytes);
 123 void iov_iter_revert(struct iov_iter *i, size_t bytes);
 124 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
 125 size_t iov_iter_single_seg_count(const struct iov_iter *i);
 126 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
 127                          struct iov_iter *i);
 128 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
 129                          struct iov_iter *i);
 130
 131 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
 132 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
 133 bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i);
 134 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
 135 bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i);
 136
 137 static __always_inline __must_check
 138 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
 139 {
 140         if (unlikely(!check_copy_size(addr, bytes, true)))
 141                 return 0;
 142         else
 143                 return _copy_to_iter(addr, bytes, i);
 144 }
 145
 146 static __always_inline __must_check
 147 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
 148 {
 149         if (unlikely(!check_copy_size(addr, bytes, false)))
 150                 return 0;
 151         else
 152                 return _copy_from_iter(addr, bytes, i);
 153 }
 154
 155 static __always_inline __must_check
 156 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
 157 {
 158         if (unlikely(!check_copy_size(addr, bytes, false)))
 159                 return false;
 160         else
 161                 return _copy_from_iter_full(addr, bytes, i);
 162 }
 163
 164 static __always_inline __must_check
 165 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
 166 {
 167         if (unlikely(!check_copy_size(addr, bytes, false)))
 168                 return 0;
 169         else
 170                 return _copy_from_iter_nocache(addr, bytes, i);
 171 }
 172
 173 static __always_inline __must_check
 174 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
 175 {
 176         if (unlikely(!check_copy_size(addr, bytes, false)))
 177                 return false;
 178         else
 179                 return _copy_from_iter_full_nocache(addr, bytes, i);
 180 }
 181
 182 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
 183 /*
 184  * Note, users like pmem that depend on the stricter semantics of
 185  * copy_from_iter_flushcache() than copy_from_iter_nocache() must check for
 186  * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
 187  * destination is flushed from the cache on return.
 188  */
 189 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
 190 #else
 191 #define _copy_from_iter_flushcache _copy_from_iter_nocache
 192 #endif
 193
 194 #ifdef CONFIG_ARCH_HAS_UACCESS_MCSAFE
 195 size_t _copy_to_iter_mcsafe(const void *addr, size_t bytes, struct iov_iter *i);
 196 #else
 197 #define _copy_to_iter_mcsafe _copy_to_iter
 198 #endif
 199
 200 static __always_inline __must_check
 201 size_t copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
 202 {
 203         if (unlikely(!check_copy_size(addr, bytes, false)))
 204                 return 0;
 205         else
 206                 return _copy_from_iter_flushcache(addr, bytes, i);
 207 }
 208
 209 static __always_inline __must_check
 210 size_t copy_to_iter_mcsafe(void *addr, size_t bytes, struct iov_iter *i)
 211 {
 212         if (unlikely(!check_copy_size(addr, bytes, true)))
 213                 return 0;
 214         else
 215                 return _copy_to_iter_mcsafe(addr, bytes, i);
 216 }
 217
 218 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
 219 unsigned long iov_iter_alignment(const struct iov_iter *i);
 220 unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
 221 void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
 222                         unsigned long nr_segs, size_t count);
 223 void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
 224                         unsigned long nr_segs, size_t count);
 225 void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
 226                         unsigned long nr_segs, size_t count);
 227 void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
 228                         size_t count);
 229 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
 230 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
 231                         size_t maxsize, unsigned maxpages, size_t *start);
 232 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
 233                         size_t maxsize, size_t *start);
 234 int iov_iter_npages(const struct iov_iter *i, int maxpages);
 235
 236 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
 237
 238 static inline size_t iov_iter_count(const struct iov_iter *i)
 239 {
 240         return i->count;
 241 }
 242
 243 /*
 244  * Cap the iov_iter by given limit; note that the second argument is
 245  * *not* the new size - it's upper limit for such.  Passing it a value
 246  * greater than the amount of data in iov_iter is fine - it'll just do
 247  * nothing in that case.
 248  */
 249 static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
 250 {
 251         /*
 252          * count doesn't have to fit in size_t - comparison extends both
 253          * operands to u64 here and any value that would be truncated by
 254          * conversion in assignement is by definition greater than all
 255          * values of size_t, including old i->count.
 256          */
 257         if (i->count > count)
 258                 i->count = count;
 259 }
 260
 261 /*
 262  * reexpand a previously truncated iterator; count must be no more than how much
 263  * we had shrunk it.
 264  */
 265 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
 266 {
 267         i->count = count;
 268 }
 269 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 270 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 271 bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 272
 273 int import_iovec(int type, const struct iovec __user * uvector,
 274                  unsigned nr_segs, unsigned fast_segs,
 275                  struct iovec **iov, struct iov_iter *i);
 276
 277 #ifdef CONFIG_COMPAT
 278 struct compat_iovec;
 279 int compat_import_iovec(int type, const struct compat_iovec __user * uvector,
 280                  unsigned nr_segs, unsigned fast_segs,
 281                  struct iovec **iov, struct iov_iter *i);
 282 #endif
 283
 284 int import_single_range(int type, void __user *buf, size_t len,
 285                  struct iovec *iov, struct iov_iter *i);
 286
 287 int iov_iter_for_each_range(struct iov_iter *i, size_t bytes,
 288                             int (*f)(struct kvec *vec, void *context),
 289                             void *context);
 290
 291 #endif