include/linux/uio.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  *      Berkeley style UIO structures   -       Alan Cox 1994.
   4  */
   5 #ifndef __LINUX_UIO_H
   6 #define __LINUX_UIO_H
   7
   8 #include <linux/kernel.h>
   9 #include <linux/thread_info.h>
  10 #include <uapi/linux/uio.h>
  11
  12 struct page;
  13 struct pipe_inode_info;
  14
  15 struct kvec {
  16         void *iov_base; /* and that should *never* hold a userland pointer */
  17         size_t iov_len;
  18 };
  19
  20 enum iter_type {
  21         /* iter types */
  22         ITER_IOVEC,
  23         ITER_KVEC,
  24         ITER_BVEC,
  25         ITER_PIPE,
  26         ITER_XARRAY,
  27         ITER_DISCARD,
  28 };
  29
  30 struct iov_iter {
  31         u8 iter_type;
  32         bool data_source;
  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 xarray *xarray;
  40                 struct pipe_inode_info *pipe;
  41         };
  42         union {
  43                 unsigned long nr_segs;
  44                 struct {
  45                         unsigned int head;
  46                         unsigned int start_head;
  47                 };
  48                 loff_t xarray_start;
  49         };
  50         size_t truncated;
  51 };
  52
  53 static inline enum iter_type iov_iter_type(const struct iov_iter *i)
  54 {
  55         return i->iter_type;
  56 }
  57
  58 static inline bool iter_is_iovec(const struct iov_iter *i)
  59 {
  60         return iov_iter_type(i) == ITER_IOVEC;
  61 }
  62
  63 static inline bool iov_iter_is_kvec(const struct iov_iter *i)
  64 {
  65         return iov_iter_type(i) == ITER_KVEC;
  66 }
  67
  68 static inline bool iov_iter_is_bvec(const struct iov_iter *i)
  69 {
  70         return iov_iter_type(i) == ITER_BVEC;
  71 }
  72
  73 static inline bool iov_iter_is_pipe(const struct iov_iter *i)
  74 {
  75         return iov_iter_type(i) == ITER_PIPE;
  76 }
  77
  78 static inline bool iov_iter_is_discard(const struct iov_iter *i)
  79 {
  80         return iov_iter_type(i) == ITER_DISCARD;
  81 }
  82
  83 static inline bool iov_iter_is_xarray(const struct iov_iter *i)
  84 {
  85         return iov_iter_type(i) == ITER_XARRAY;
  86 }
  87
  88 static inline unsigned char iov_iter_rw(const struct iov_iter *i)
  89 {
  90         return i->data_source ? WRITE : READ;
  91 }
  92
  93 /*
  94  * Total number of bytes covered by an iovec.
  95  *
  96  * NOTE that it is not safe to use this function until all the iovec's
  97  * segment lengths have been validated.  Because the individual lengths can
  98  * overflow a size_t when added together.
  99  */
 100 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
 101 {
 102         unsigned long seg;
 103         size_t ret = 0;
 104
 105         for (seg = 0; seg < nr_segs; seg++)
 106                 ret += iov[seg].iov_len;
 107         return ret;
 108 }
 109
 110 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
 111 {
 112         return (struct iovec) {
 113                 .iov_base = iter->iov->iov_base + iter->iov_offset,
 114                 .iov_len = min(iter->count,
 115                                iter->iov->iov_len - iter->iov_offset),
 116         };
 117 }
 118
 119 size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
 120                                   size_t bytes, struct iov_iter *i);
 121 void iov_iter_advance(struct iov_iter *i, size_t bytes);
 122 void iov_iter_revert(struct iov_iter *i, size_t bytes);
 123 int iov_iter_fault_in_readable(const struct iov_iter *i, size_t bytes);
 124 size_t iov_iter_single_seg_count(const struct iov_iter *i);
 125 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
 126                          struct iov_iter *i);
 127 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
 128                          struct iov_iter *i);
 129
 130 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
 131 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
 132 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
 133
 134 static __always_inline __must_check
 135 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
 136 {
 137         if (unlikely(!check_copy_size(addr, bytes, true)))
 138                 return 0;
 139         else
 140                 return _copy_to_iter(addr, bytes, i);
 141 }
 142
 143 static __always_inline __must_check
 144 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
 145 {
 146         if (unlikely(!check_copy_size(addr, bytes, false)))
 147                 return 0;
 148         else
 149                 return _copy_from_iter(addr, bytes, i);
 150 }
 151
 152 static __always_inline __must_check
 153 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
 154 {
 155         size_t copied = copy_from_iter(addr, bytes, i);
 156         if (likely(copied == bytes))
 157                 return true;
 158         iov_iter_revert(i, copied);
 159         return false;
 160 }
 161
 162 static __always_inline __must_check
 163 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
 164 {
 165         if (unlikely(!check_copy_size(addr, bytes, false)))
 166                 return 0;
 167         else
 168                 return _copy_from_iter_nocache(addr, bytes, i);
 169 }
 170
 171 static __always_inline __must_check
 172 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
 173 {
 174         size_t copied = copy_from_iter_nocache(addr, bytes, i);
 175         if (likely(copied == bytes))
 176                 return true;
 177         iov_iter_revert(i, copied);
 178         return false;
 179 }
 180
 181 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
 182 /*
 183  * Note, users like pmem that depend on the stricter semantics of
 184  * copy_from_iter_flushcache() than copy_from_iter_nocache() must check for
 185  * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
 186  * destination is flushed from the cache on return.
 187  */
 188 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
 189 #else
 190 #define _copy_from_iter_flushcache _copy_from_iter_nocache
 191 #endif
 192
 193 #ifdef CONFIG_ARCH_HAS_COPY_MC
 194 size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
 195 #else
 196 #define _copy_mc_to_iter _copy_to_iter
 197 #endif
 198
 199 static __always_inline __must_check
 200 size_t copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
 201 {
 202         if (unlikely(!check_copy_size(addr, bytes, false)))
 203                 return 0;
 204         else
 205                 return _copy_from_iter_flushcache(addr, bytes, i);
 206 }
 207
 208 static __always_inline __must_check
 209 size_t copy_mc_to_iter(void *addr, size_t bytes, struct iov_iter *i)
 210 {
 211         if (unlikely(!check_copy_size(addr, bytes, true)))
 212                 return 0;
 213         else
 214                 return _copy_mc_to_iter(addr, bytes, i);
 215 }
 216
 217 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
 218 unsigned long iov_iter_alignment(const struct iov_iter *i);
 219 unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
 220 void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
 221                         unsigned long nr_segs, size_t count);
 222 void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
 223                         unsigned long nr_segs, size_t count);
 224 void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
 225                         unsigned long nr_segs, size_t count);
 226 void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
 227                         size_t count);
 228 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
 229 void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
 230                      loff_t start, size_t count);
 231 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
 232                         size_t maxsize, unsigned maxpages, size_t *start);
 233 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
 234                         size_t maxsize, size_t *start);
 235 int iov_iter_npages(const struct iov_iter *i, int maxpages);
 236
 237 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
 238
 239 static inline size_t iov_iter_count(const struct iov_iter *i)
 240 {
 241         return i->count;
 242 }
 243
 244 /*
 245  * Cap the iov_iter by given limit; note that the second argument is
 246  * *not* the new size - it's upper limit for such.  Passing it a value
 247  * greater than the amount of data in iov_iter is fine - it'll just do
 248  * nothing in that case.
 249  */
 250 static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
 251 {
 252         /*
 253          * count doesn't have to fit in size_t - comparison extends both
 254          * operands to u64 here and any value that would be truncated by
 255          * conversion in assignement is by definition greater than all
 256          * values of size_t, including old i->count.
 257          */
 258         if (i->count > count) {
 259                 i->truncated += i->count - count;
 260                 i->count = count;
 261         }
 262 }
 263
 264 /*
 265  * reexpand a previously truncated iterator; count must be no more than how much
 266  * we had shrunk it.
 267  */
 268 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
 269 {
 270         i->truncated -= count - i->count;
 271         i->count = count;
 272 }
 273
 274 struct csum_state {
 275         __wsum csum;
 276         size_t off;
 277 };
 278
 279 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i);
 280 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 281
 282 static __always_inline __must_check
 283 bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
 284                                   __wsum *csum, struct iov_iter *i)
 285 {
 286         size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i);
 287         if (likely(copied == bytes))
 288                 return true;
 289         iov_iter_revert(i, copied);
 290         return false;
 291 }
 292 size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
 293                 struct iov_iter *i);
 294
 295 struct iovec *iovec_from_user(const struct iovec __user *uvector,
 296                 unsigned long nr_segs, unsigned long fast_segs,
 297                 struct iovec *fast_iov, bool compat);
 298 ssize_t import_iovec(int type, const struct iovec __user *uvec,
 299                  unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
 300                  struct iov_iter *i);
 301 ssize_t __import_iovec(int type, const struct iovec __user *uvec,
 302                  unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
 303                  struct iov_iter *i, bool compat);
 304 int import_single_range(int type, void __user *buf, size_t len,
 305                  struct iovec *iov, struct iov_iter *i);
 306
 307 #endif