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 <crypto/hash.h>
  15 #include <uapi/linux/uio.h>
  16
  17 struct page;
  18 struct pipe_inode_info;
  19
  20 struct kvec {
  21         void *iov_base; /* and that should *never* hold a userland pointer */
  22         size_t iov_len;
  23 };
  24
  25 enum iter_type {
  26         /* set if ITER_BVEC doesn't hold a bv_page ref */
  27         ITER_BVEC_FLAG_NO_REF = 2,
  28
  29         /* iter types */
  30         ITER_IOVEC = 4,
  31         ITER_KVEC = 8,
  32         ITER_BVEC = 16,
  33         ITER_PIPE = 32,
  34         ITER_DISCARD = 64,
  35 };
  36
  37 struct iov_iter {
  38         /*
  39          * Bit 0 is the read/write bit, set if we're writing.
  40          * Bit 1 is the BVEC_FLAG_NO_REF bit, set if type is a bvec and
  41          * the caller isn't expecting to drop a page reference when done.
  42          */
  43         unsigned int type;
  44         size_t iov_offset;
  45         size_t count;
  46         union {
  47                 const struct iovec *iov;
  48                 const struct kvec *kvec;
  49                 const struct bio_vec *bvec;
  50                 struct pipe_inode_info *pipe;
  51         };
  52         union {
  53                 unsigned long nr_segs;
  54                 struct {
  55                         int idx;
  56                         int start_idx;
  57                 };
  58         };
  59 };
  60
  61 static inline enum iter_type iov_iter_type(const struct iov_iter *i)
  62 {
  63         return i->type & ~(READ | WRITE);
  64 }
  65
  66 static inline bool iter_is_iovec(const struct iov_iter *i)
  67 {
  68         return iov_iter_type(i) == ITER_IOVEC;
  69 }
  70
  71 static inline bool iov_iter_is_kvec(const struct iov_iter *i)
  72 {
  73         return iov_iter_type(i) == ITER_KVEC;
  74 }
  75
  76 static inline bool iov_iter_is_bvec(const struct iov_iter *i)
  77 {
  78         return iov_iter_type(i) == ITER_BVEC;
  79 }
  80
  81 static inline bool iov_iter_is_pipe(const struct iov_iter *i)
  82 {
  83         return iov_iter_type(i) == ITER_PIPE;
  84 }
  85
  86 static inline bool iov_iter_is_discard(const struct iov_iter *i)
  87 {
  88         return iov_iter_type(i) == ITER_DISCARD;
  89 }
  90
  91 static inline unsigned char iov_iter_rw(const struct iov_iter *i)
  92 {
  93         return i->type & (READ | WRITE);
  94 }
  95
  96 static inline bool iov_iter_bvec_no_ref(const struct iov_iter *i)
  97 {
  98         return (i->type & ITER_BVEC_FLAG_NO_REF) != 0;
  99 }
 100
 101 /*
 102  * Total number of bytes covered by an iovec.
 103  *
 104  * NOTE that it is not safe to use this function until all the iovec's
 105  * segment lengths have been validated.  Because the individual lengths can
 106  * overflow a size_t when added together.
 107  */
 108 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
 109 {
 110         unsigned long seg;
 111         size_t ret = 0;
 112
 113         for (seg = 0; seg < nr_segs; seg++)
 114                 ret += iov[seg].iov_len;
 115         return ret;
 116 }
 117
 118 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
 119 {
 120         return (struct iovec) {
 121                 .iov_base = iter->iov->iov_base + iter->iov_offset,
 122                 .iov_len = min(iter->count,
 123                                iter->iov->iov_len - iter->iov_offset),
 124         };
 125 }
 126
 127 size_t iov_iter_copy_from_user_atomic(struct page *page,
 128                 struct iov_iter *i, unsigned long offset, size_t bytes);
 129 void iov_iter_advance(struct iov_iter *i, size_t bytes);
 130 void iov_iter_revert(struct iov_iter *i, size_t bytes);
 131 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
 132 size_t iov_iter_single_seg_count(const struct iov_iter *i);
 133 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
 134                          struct iov_iter *i);
 135 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
 136                          struct iov_iter *i);
 137
 138 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
 139 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
 140 bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i);
 141 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
 142 bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i);
 143
 144 static __always_inline __must_check
 145 size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
 146 {
 147         if (unlikely(!check_copy_size(addr, bytes, true)))
 148                 return 0;
 149         else
 150                 return _copy_to_iter(addr, bytes, i);
 151 }
 152
 153 static __always_inline __must_check
 154 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
 155 {
 156         if (unlikely(!check_copy_size(addr, bytes, false)))
 157                 return 0;
 158         else
 159                 return _copy_from_iter(addr, bytes, i);
 160 }
 161
 162 static __always_inline __must_check
 163 bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
 164 {
 165         if (unlikely(!check_copy_size(addr, bytes, false)))
 166                 return false;
 167         else
 168                 return _copy_from_iter_full(addr, bytes, i);
 169 }
 170
 171 static __always_inline __must_check
 172 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
 173 {
 174         if (unlikely(!check_copy_size(addr, bytes, false)))
 175                 return 0;
 176         else
 177                 return _copy_from_iter_nocache(addr, bytes, i);
 178 }
 179
 180 static __always_inline __must_check
 181 bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
 182 {
 183         if (unlikely(!check_copy_size(addr, bytes, false)))
 184                 return false;
 185         else
 186                 return _copy_from_iter_full_nocache(addr, bytes, i);
 187 }
 188
 189 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
 190 /*
 191  * Note, users like pmem that depend on the stricter semantics of
 192  * copy_from_iter_flushcache() than copy_from_iter_nocache() must check for
 193  * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the
 194  * destination is flushed from the cache on return.
 195  */
 196 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i);
 197 #else
 198 #define _copy_from_iter_flushcache _copy_from_iter_nocache
 199 #endif
 200
 201 #ifdef CONFIG_ARCH_HAS_UACCESS_MCSAFE
 202 size_t _copy_to_iter_mcsafe(const void *addr, size_t bytes, struct iov_iter *i);
 203 #else
 204 #define _copy_to_iter_mcsafe _copy_to_iter
 205 #endif
 206
 207 static __always_inline __must_check
 208 size_t copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
 209 {
 210         if (unlikely(!check_copy_size(addr, bytes, false)))
 211                 return 0;
 212         else
 213                 return _copy_from_iter_flushcache(addr, bytes, i);
 214 }
 215
 216 static __always_inline __must_check
 217 size_t copy_to_iter_mcsafe(void *addr, size_t bytes, struct iov_iter *i)
 218 {
 219         if (unlikely(!check_copy_size(addr, bytes, true)))
 220                 return 0;
 221         else
 222                 return _copy_to_iter_mcsafe(addr, bytes, i);
 223 }
 224
 225 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
 226 unsigned long iov_iter_alignment(const struct iov_iter *i);
 227 unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
 228 void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
 229                         unsigned long nr_segs, size_t count);
 230 void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec,
 231                         unsigned long nr_segs, size_t count);
 232 void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
 233                         unsigned long nr_segs, size_t count);
 234 void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
 235                         size_t count);
 236 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
 237 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
 238                         size_t maxsize, unsigned maxpages, size_t *start);
 239 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
 240                         size_t maxsize, size_t *start);
 241 int iov_iter_npages(const struct iov_iter *i, int maxpages);
 242
 243 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
 244
 245 static inline size_t iov_iter_count(const struct iov_iter *i)
 246 {
 247         return i->count;
 248 }
 249
 250 /*
 251  * Cap the iov_iter by given limit; note that the second argument is
 252  * *not* the new size - it's upper limit for such.  Passing it a value
 253  * greater than the amount of data in iov_iter is fine - it'll just do
 254  * nothing in that case.
 255  */
 256 static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
 257 {
 258         /*
 259          * count doesn't have to fit in size_t - comparison extends both
 260          * operands to u64 here and any value that would be truncated by
 261          * conversion in assignement is by definition greater than all
 262          * values of size_t, including old i->count.
 263          */
 264         if (i->count > count)
 265                 i->count = count;
 266 }
 267
 268 /*
 269  * reexpand a previously truncated iterator; count must be no more than how much
 270  * we had shrunk it.
 271  */
 272 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
 273 {
 274         i->count = count;
 275 }
 276 size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csump, struct iov_iter *i);
 277 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 278 bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 279 size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
 280                 struct iov_iter *i);
 281
 282 int import_iovec(int type, const struct iovec __user * uvector,
 283                  unsigned nr_segs, unsigned fast_segs,
 284                  struct iovec **iov, struct iov_iter *i);
 285
 286 #ifdef CONFIG_COMPAT
 287 struct compat_iovec;
 288 int compat_import_iovec(int type, const struct compat_iovec __user * uvector,
 289                  unsigned nr_segs, unsigned fast_segs,
 290                  struct iovec **iov, struct iov_iter *i);
 291 #endif
 292
 293 int import_single_range(int type, void __user *buf, size_t len,
 294                  struct iovec *iov, struct iov_iter *i);
 295
 296 int iov_iter_for_each_range(struct iov_iter *i, size_t bytes,
 297                             int (*f)(struct kvec *vec, void *context),
 298                             void *context);
 299
 300 #endif