fs/readdir.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/readdir.c
   4  *
   5  *  Copyright (C) 1995  Linus Torvalds
   6  */
   7
   8 #include <linux/stddef.h>
   9 #include <linux/kernel.h>
  10 #include <linux/export.h>
  11 #include <linux/time.h>
  12 #include <linux/mm.h>
  13 #include <linux/errno.h>
  14 #include <linux/stat.h>
  15 #include <linux/file.h>
  16 #include <linux/fs.h>
  17 #include <linux/fsnotify.h>
  18 #include <linux/dirent.h>
  19 #include <linux/security.h>
  20 #include <linux/syscalls.h>
  21 #include <linux/unistd.h>
  22 #include <linux/compat.h>
  23
  24 #include <linux/uaccess.h>
  25
  26 int iterate_dir(struct file *file, struct dir_context *ctx)
  27 {
  28         struct inode *inode = file_inode(file);
  29         bool shared = false;
  30         int res = -ENOTDIR;
  31         if (file->f_op->iterate_shared)
  32                 shared = true;
  33         else if (!file->f_op->iterate)
  34                 goto out;
  35
  36         res = security_file_permission(file, MAY_READ);
  37         if (res)
  38                 goto out;
  39
  40         if (shared)
  41                 res = down_read_killable(&inode->i_rwsem);
  42         else
  43                 res = down_write_killable(&inode->i_rwsem);
  44         if (res)
  45                 goto out;
  46
  47         res = -ENOENT;
  48         if (!IS_DEADDIR(inode)) {
  49                 ctx->pos = file->f_pos;
  50                 if (shared)
  51                         res = file->f_op->iterate_shared(file, ctx);
  52                 else
  53                         res = file->f_op->iterate(file, ctx);
  54                 file->f_pos = ctx->pos;
  55                 fsnotify_access(file);
  56                 file_accessed(file);
  57         }
  58         if (shared)
  59                 inode_unlock_shared(inode);
  60         else
  61                 inode_unlock(inode);
  62 out:
  63         return res;
  64 }
  65 EXPORT_SYMBOL(iterate_dir);
  66
  67 /*
  68  * Traditional linux readdir() handling..
  69  *
  70  * "count=1" is a special case, meaning that the buffer is one
  71  * dirent-structure in size and that the code can't handle more
  72  * anyway. Thus the special "fillonedir()" function for that
  73  * case (the low-level handlers don't need to care about this).
  74  */
  75
  76 #ifdef __ARCH_WANT_OLD_READDIR
  77
  78 struct old_linux_dirent {
  79         unsigned long   d_ino;
  80         unsigned long   d_offset;
  81         unsigned short  d_namlen;
  82         char            d_name[1];
  83 };
  84
  85 struct readdir_callback {
  86         struct dir_context ctx;
  87         struct old_linux_dirent __user * dirent;
  88         int result;
  89 };
  90
  91 static int fillonedir(struct dir_context *ctx, const char *name, int namlen,
  92                       loff_t offset, u64 ino, unsigned int d_type)
  93 {
  94         struct readdir_callback *buf =
  95                 container_of(ctx, struct readdir_callback, ctx);
  96         struct old_linux_dirent __user * dirent;
  97         unsigned long d_ino;
  98
  99         if (buf->result)
 100                 return -EINVAL;
 101         d_ino = ino;
 102         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
 103                 buf->result = -EOVERFLOW;
 104                 return -EOVERFLOW;
 105         }
 106         buf->result++;
 107         dirent = buf->dirent;
 108         if (!access_ok(dirent,
 109                         (unsigned long)(dirent->d_name + namlen + 1) -
 110                                 (unsigned long)dirent))
 111                 goto efault;
 112         if (    __put_user(d_ino, &dirent->d_ino) ||
 113                 __put_user(offset, &dirent->d_offset) ||
 114                 __put_user(namlen, &dirent->d_namlen) ||
 115                 __copy_to_user(dirent->d_name, name, namlen) ||
 116                 __put_user(0, dirent->d_name + namlen))
 117                 goto efault;
 118         return 0;
 119 efault:
 120         buf->result = -EFAULT;
 121         return -EFAULT;
 122 }
 123
 124 SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
 125                 struct old_linux_dirent __user *, dirent, unsigned int, count)
 126 {
 127         int error;
 128         struct fd f = fdget_pos(fd);
 129         struct readdir_callback buf = {
 130                 .ctx.actor = fillonedir,
 131                 .dirent = dirent
 132         };
 133
 134         if (!f.file)
 135                 return -EBADF;
 136
 137         error = iterate_dir(f.file, &buf.ctx);
 138         if (buf.result)
 139                 error = buf.result;
 140
 141         fdput_pos(f);
 142         return error;
 143 }
 144
 145 #endif /* __ARCH_WANT_OLD_READDIR */
 146
 147 /*
 148  * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 149  * interface.
 150  */
 151 struct linux_dirent {
 152         unsigned long   d_ino;
 153         unsigned long   d_off;
 154         unsigned short  d_reclen;
 155         char            d_name[1];
 156 };
 157
 158 struct getdents_callback {
 159         struct dir_context ctx;
 160         struct linux_dirent __user * current_dir;
 161         struct linux_dirent __user * previous;
 162         int count;
 163         int error;
 164 };
 165
 166 static int filldir(struct dir_context *ctx, const char *name, int namlen,
 167                    loff_t offset, u64 ino, unsigned int d_type)
 168 {
 169         struct linux_dirent __user * dirent;
 170         struct getdents_callback *buf =
 171                 container_of(ctx, struct getdents_callback, ctx);
 172         unsigned long d_ino;
 173         int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
 174                 sizeof(long));
 175
 176         buf->error = -EINVAL;   /* only used if we fail.. */
 177         if (reclen > buf->count)
 178                 return -EINVAL;
 179         d_ino = ino;
 180         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
 181                 buf->error = -EOVERFLOW;
 182                 return -EOVERFLOW;
 183         }
 184         dirent = buf->previous;
 185         if (dirent) {
 186                 if (signal_pending(current))
 187                         return -EINTR;
 188                 if (__put_user(offset, &dirent->d_off))
 189                         goto efault;
 190         }
 191         dirent = buf->current_dir;
 192         if (__put_user(d_ino, &dirent->d_ino))
 193                 goto efault;
 194         if (__put_user(reclen, &dirent->d_reclen))
 195                 goto efault;
 196         if (copy_to_user(dirent->d_name, name, namlen))
 197                 goto efault;
 198         if (__put_user(0, dirent->d_name + namlen))
 199                 goto efault;
 200         if (__put_user(d_type, (char __user *) dirent + reclen - 1))
 201                 goto efault;
 202         buf->previous = dirent;
 203         dirent = (void __user *)dirent + reclen;
 204         buf->current_dir = dirent;
 205         buf->count -= reclen;
 206         return 0;
 207 efault:
 208         buf->error = -EFAULT;
 209         return -EFAULT;
 210 }
 211
 212 SYSCALL_DEFINE3(getdents, unsigned int, fd,
 213                 struct linux_dirent __user *, dirent, unsigned int, count)
 214 {
 215         struct fd f;
 216         struct linux_dirent __user * lastdirent;
 217         struct getdents_callback buf = {
 218                 .ctx.actor = filldir,
 219                 .count = count,
 220                 .current_dir = dirent
 221         };
 222         int error;
 223
 224         if (!access_ok(dirent, count))
 225                 return -EFAULT;
 226
 227         f = fdget_pos(fd);
 228         if (!f.file)
 229                 return -EBADF;
 230
 231         error = iterate_dir(f.file, &buf.ctx);
 232         if (error >= 0)
 233                 error = buf.error;
 234         lastdirent = buf.previous;
 235         if (lastdirent) {
 236                 if (put_user(buf.ctx.pos, &lastdirent->d_off))
 237                         error = -EFAULT;
 238                 else
 239                         error = count - buf.count;
 240         }
 241         fdput_pos(f);
 242         return error;
 243 }
 244
 245 struct getdents_callback64 {
 246         struct dir_context ctx;
 247         struct linux_dirent64 __user * current_dir;
 248         struct linux_dirent64 __user * previous;
 249         int count;
 250         int error;
 251 };
 252
 253 static int filldir64(struct dir_context *ctx, const char *name, int namlen,
 254                      loff_t offset, u64 ino, unsigned int d_type)
 255 {
 256         struct linux_dirent64 __user *dirent;
 257         struct getdents_callback64 *buf =
 258                 container_of(ctx, struct getdents_callback64, ctx);
 259         int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
 260                 sizeof(u64));
 261
 262         buf->error = -EINVAL;   /* only used if we fail.. */
 263         if (reclen > buf->count)
 264                 return -EINVAL;
 265         dirent = buf->previous;
 266         if (dirent) {
 267                 if (signal_pending(current))
 268                         return -EINTR;
 269                 if (__put_user(offset, &dirent->d_off))
 270                         goto efault;
 271         }
 272         dirent = buf->current_dir;
 273         if (__put_user(ino, &dirent->d_ino))
 274                 goto efault;
 275         if (__put_user(0, &dirent->d_off))
 276                 goto efault;
 277         if (__put_user(reclen, &dirent->d_reclen))
 278                 goto efault;
 279         if (__put_user(d_type, &dirent->d_type))
 280                 goto efault;
 281         if (copy_to_user(dirent->d_name, name, namlen))
 282                 goto efault;
 283         if (__put_user(0, dirent->d_name + namlen))
 284                 goto efault;
 285         buf->previous = dirent;
 286         dirent = (void __user *)dirent + reclen;
 287         buf->current_dir = dirent;
 288         buf->count -= reclen;
 289         return 0;
 290 efault:
 291         buf->error = -EFAULT;
 292         return -EFAULT;
 293 }
 294
 295 int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent,
 296                     unsigned int count)
 297 {
 298         struct fd f;
 299         struct linux_dirent64 __user * lastdirent;
 300         struct getdents_callback64 buf = {
 301                 .ctx.actor = filldir64,
 302                 .count = count,
 303                 .current_dir = dirent
 304         };
 305         int error;
 306
 307         if (!access_ok(dirent, count))
 308                 return -EFAULT;
 309
 310         f = fdget_pos(fd);
 311         if (!f.file)
 312                 return -EBADF;
 313
 314         error = iterate_dir(f.file, &buf.ctx);
 315         if (error >= 0)
 316                 error = buf.error;
 317         lastdirent = buf.previous;
 318         if (lastdirent) {
 319                 typeof(lastdirent->d_off) d_off = buf.ctx.pos;
 320                 if (__put_user(d_off, &lastdirent->d_off))
 321                         error = -EFAULT;
 322                 else
 323                         error = count - buf.count;
 324         }
 325         fdput_pos(f);
 326         return error;
 327 }
 328
 329
 330 SYSCALL_DEFINE3(getdents64, unsigned int, fd,
 331                 struct linux_dirent64 __user *, dirent, unsigned int, count)
 332 {
 333         return ksys_getdents64(fd, dirent, count);
 334 }
 335
 336 #ifdef CONFIG_COMPAT
 337 struct compat_old_linux_dirent {
 338         compat_ulong_t  d_ino;
 339         compat_ulong_t  d_offset;
 340         unsigned short  d_namlen;
 341         char            d_name[1];
 342 };
 343
 344 struct compat_readdir_callback {
 345         struct dir_context ctx;
 346         struct compat_old_linux_dirent __user *dirent;
 347         int result;
 348 };
 349
 350 static int compat_fillonedir(struct dir_context *ctx, const char *name,
 351                              int namlen, loff_t offset, u64 ino,
 352                              unsigned int d_type)
 353 {
 354         struct compat_readdir_callback *buf =
 355                 container_of(ctx, struct compat_readdir_callback, ctx);
 356         struct compat_old_linux_dirent __user *dirent;
 357         compat_ulong_t d_ino;
 358
 359         if (buf->result)
 360                 return -EINVAL;
 361         d_ino = ino;
 362         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
 363                 buf->result = -EOVERFLOW;
 364                 return -EOVERFLOW;
 365         }
 366         buf->result++;
 367         dirent = buf->dirent;
 368         if (!access_ok(dirent,
 369                         (unsigned long)(dirent->d_name + namlen + 1) -
 370                                 (unsigned long)dirent))
 371                 goto efault;
 372         if (    __put_user(d_ino, &dirent->d_ino) ||
 373                 __put_user(offset, &dirent->d_offset) ||
 374                 __put_user(namlen, &dirent->d_namlen) ||
 375                 __copy_to_user(dirent->d_name, name, namlen) ||
 376                 __put_user(0, dirent->d_name + namlen))
 377                 goto efault;
 378         return 0;
 379 efault:
 380         buf->result = -EFAULT;
 381         return -EFAULT;
 382 }
 383
 384 COMPAT_SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
 385                 struct compat_old_linux_dirent __user *, dirent, unsigned int, count)
 386 {
 387         int error;
 388         struct fd f = fdget_pos(fd);
 389         struct compat_readdir_callback buf = {
 390                 .ctx.actor = compat_fillonedir,
 391                 .dirent = dirent
 392         };
 393
 394         if (!f.file)
 395                 return -EBADF;
 396
 397         error = iterate_dir(f.file, &buf.ctx);
 398         if (buf.result)
 399                 error = buf.result;
 400
 401         fdput_pos(f);
 402         return error;
 403 }
 404
 405 struct compat_linux_dirent {
 406         compat_ulong_t  d_ino;
 407         compat_ulong_t  d_off;
 408         unsigned short  d_reclen;
 409         char            d_name[1];
 410 };
 411
 412 struct compat_getdents_callback {
 413         struct dir_context ctx;
 414         struct compat_linux_dirent __user *current_dir;
 415         struct compat_linux_dirent __user *previous;
 416         int count;
 417         int error;
 418 };
 419
 420 static int compat_filldir(struct dir_context *ctx, const char *name, int namlen,
 421                 loff_t offset, u64 ino, unsigned int d_type)
 422 {
 423         struct compat_linux_dirent __user * dirent;
 424         struct compat_getdents_callback *buf =
 425                 container_of(ctx, struct compat_getdents_callback, ctx);
 426         compat_ulong_t d_ino;
 427         int reclen = ALIGN(offsetof(struct compat_linux_dirent, d_name) +
 428                 namlen + 2, sizeof(compat_long_t));
 429
 430         buf->error = -EINVAL;   /* only used if we fail.. */
 431         if (reclen > buf->count)
 432                 return -EINVAL;
 433         d_ino = ino;
 434         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
 435                 buf->error = -EOVERFLOW;
 436                 return -EOVERFLOW;
 437         }
 438         dirent = buf->previous;
 439         if (dirent) {
 440                 if (signal_pending(current))
 441                         return -EINTR;
 442                 if (__put_user(offset, &dirent->d_off))
 443                         goto efault;
 444         }
 445         dirent = buf->current_dir;
 446         if (__put_user(d_ino, &dirent->d_ino))
 447                 goto efault;
 448         if (__put_user(reclen, &dirent->d_reclen))
 449                 goto efault;
 450         if (copy_to_user(dirent->d_name, name, namlen))
 451                 goto efault;
 452         if (__put_user(0, dirent->d_name + namlen))
 453                 goto efault;
 454         if (__put_user(d_type, (char  __user *) dirent + reclen - 1))
 455                 goto efault;
 456         buf->previous = dirent;
 457         dirent = (void __user *)dirent + reclen;
 458         buf->current_dir = dirent;
 459         buf->count -= reclen;
 460         return 0;
 461 efault:
 462         buf->error = -EFAULT;
 463         return -EFAULT;
 464 }
 465
 466 COMPAT_SYSCALL_DEFINE3(getdents, unsigned int, fd,
 467                 struct compat_linux_dirent __user *, dirent, unsigned int, count)
 468 {
 469         struct fd f;
 470         struct compat_linux_dirent __user * lastdirent;
 471         struct compat_getdents_callback buf = {
 472                 .ctx.actor = compat_filldir,
 473                 .current_dir = dirent,
 474                 .count = count
 475         };
 476         int error;
 477
 478         if (!access_ok(dirent, count))
 479                 return -EFAULT;
 480
 481         f = fdget_pos(fd);
 482         if (!f.file)
 483                 return -EBADF;
 484
 485         error = iterate_dir(f.file, &buf.ctx);
 486         if (error >= 0)
 487                 error = buf.error;
 488         lastdirent = buf.previous;
 489         if (lastdirent) {
 490                 if (put_user(buf.ctx.pos, &lastdirent->d_off))
 491                         error = -EFAULT;
 492                 else
 493                         error = count - buf.count;
 494         }
 495         fdput_pos(f);
 496         return error;
 497 }
 498 #endif