fs/readdir.c

   1 /*
   2  *  linux/fs/readdir.c
   3  *
   4  *  Copyright (C) 1995  Linus Torvalds
   5  */
   6
   7 #include <linux/stddef.h>
   8 #include <linux/kernel.h>
   9 #include <linux/export.h>
  10 #include <linux/time.h>
  11 #include <linux/mm.h>
  12 #include <linux/errno.h>
  13 #include <linux/stat.h>
  14 #include <linux/file.h>
  15 #include <linux/fs.h>
  16 #include <linux/dirent.h>
  17 #include <linux/security.h>
  18 #include <linux/syscalls.h>
  19 #include <linux/unistd.h>
  20
  21 #include <asm/uaccess.h>
  22
  23 int iterate_dir(struct file *file, struct dir_context *ctx)
  24 {
  25         struct inode *inode = file_inode(file);
  26         int res = -ENOTDIR;
  27         if (!file->f_op || !file->f_op->readdir)
  28                 goto out;
  29
  30         res = security_file_permission(file, MAY_READ);
  31         if (res)
  32                 goto out;
  33
  34         res = mutex_lock_killable(&inode->i_mutex);
  35         if (res)
  36                 goto out;
  37
  38         res = -ENOENT;
  39         if (!IS_DEADDIR(inode)) {
  40                 res = file->f_op->readdir(file, ctx, ctx->actor);
  41                 file_accessed(file);
  42         }
  43         mutex_unlock(&inode->i_mutex);
  44 out:
  45         return res;
  46 }
  47 EXPORT_SYMBOL(iterate_dir);
  48
  49 /*
  50  * Traditional linux readdir() handling..
  51  *
  52  * "count=1" is a special case, meaning that the buffer is one
  53  * dirent-structure in size and that the code can't handle more
  54  * anyway. Thus the special "fillonedir()" function for that
  55  * case (the low-level handlers don't need to care about this).
  56  */
  57
  58 #ifdef __ARCH_WANT_OLD_READDIR
  59
  60 struct old_linux_dirent {
  61         unsigned long   d_ino;
  62         unsigned long   d_offset;
  63         unsigned short  d_namlen;
  64         char            d_name[1];
  65 };
  66
  67 struct readdir_callback {
  68         struct dir_context ctx;
  69         struct old_linux_dirent __user * dirent;
  70         int result;
  71 };
  72
  73 static int fillonedir(void * __buf, const char * name, int namlen, loff_t offset,
  74                       u64 ino, unsigned int d_type)
  75 {
  76         struct readdir_callback *buf = (struct readdir_callback *) __buf;
  77         struct old_linux_dirent __user * dirent;
  78         unsigned long d_ino;
  79
  80         if (buf->result)
  81                 return -EINVAL;
  82         d_ino = ino;
  83         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
  84                 buf->result = -EOVERFLOW;
  85                 return -EOVERFLOW;
  86         }
  87         buf->result++;
  88         dirent = buf->dirent;
  89         if (!access_ok(VERIFY_WRITE, dirent,
  90                         (unsigned long)(dirent->d_name + namlen + 1) -
  91                                 (unsigned long)dirent))
  92                 goto efault;
  93         if (    __put_user(d_ino, &dirent->d_ino) ||
  94                 __put_user(offset, &dirent->d_offset) ||
  95                 __put_user(namlen, &dirent->d_namlen) ||
  96                 __copy_to_user(dirent->d_name, name, namlen) ||
  97                 __put_user(0, dirent->d_name + namlen))
  98                 goto efault;
  99         return 0;
 100 efault:
 101         buf->result = -EFAULT;
 102         return -EFAULT;
 103 }
 104
 105 SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
 106                 struct old_linux_dirent __user *, dirent, unsigned int, count)
 107 {
 108         int error;
 109         struct fd f = fdget(fd);
 110         struct readdir_callback buf;
 111
 112         if (!f.file)
 113                 return -EBADF;
 114
 115         buf.ctx.actor = fillonedir;
 116         buf.result = 0;
 117         buf.dirent = dirent;
 118
 119         error = iterate_dir(f.file, &buf.ctx);
 120         if (buf.result)
 121                 error = buf.result;
 122
 123         fdput(f);
 124         return error;
 125 }
 126
 127 #endif /* __ARCH_WANT_OLD_READDIR */
 128
 129 /*
 130  * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 131  * interface.
 132  */
 133 struct linux_dirent {
 134         unsigned long   d_ino;
 135         unsigned long   d_off;
 136         unsigned short  d_reclen;
 137         char            d_name[1];
 138 };
 139
 140 struct getdents_callback {
 141         struct dir_context ctx;
 142         struct linux_dirent __user * current_dir;
 143         struct linux_dirent __user * previous;
 144         int count;
 145         int error;
 146 };
 147
 148 static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
 149                    u64 ino, unsigned int d_type)
 150 {
 151         struct linux_dirent __user * dirent;
 152         struct getdents_callback * buf = (struct getdents_callback *) __buf;
 153         unsigned long d_ino;
 154         int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
 155                 sizeof(long));
 156
 157         buf->error = -EINVAL;   /* only used if we fail.. */
 158         if (reclen > buf->count)
 159                 return -EINVAL;
 160         d_ino = ino;
 161         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
 162                 buf->error = -EOVERFLOW;
 163                 return -EOVERFLOW;
 164         }
 165         dirent = buf->previous;
 166         if (dirent) {
 167                 if (__put_user(offset, &dirent->d_off))
 168                         goto efault;
 169         }
 170         dirent = buf->current_dir;
 171         if (__put_user(d_ino, &dirent->d_ino))
 172                 goto efault;
 173         if (__put_user(reclen, &dirent->d_reclen))
 174                 goto efault;
 175         if (copy_to_user(dirent->d_name, name, namlen))
 176                 goto efault;
 177         if (__put_user(0, dirent->d_name + namlen))
 178                 goto efault;
 179         if (__put_user(d_type, (char __user *) dirent + reclen - 1))
 180                 goto efault;
 181         buf->previous = dirent;
 182         dirent = (void __user *)dirent + reclen;
 183         buf->current_dir = dirent;
 184         buf->count -= reclen;
 185         return 0;
 186 efault:
 187         buf->error = -EFAULT;
 188         return -EFAULT;
 189 }
 190
 191 SYSCALL_DEFINE3(getdents, unsigned int, fd,
 192                 struct linux_dirent __user *, dirent, unsigned int, count)
 193 {
 194         struct fd f;
 195         struct linux_dirent __user * lastdirent;
 196         struct getdents_callback buf;
 197         int error;
 198
 199         if (!access_ok(VERIFY_WRITE, dirent, count))
 200                 return -EFAULT;
 201
 202         f = fdget(fd);
 203         if (!f.file)
 204                 return -EBADF;
 205
 206         buf.current_dir = dirent;
 207         buf.previous = NULL;
 208         buf.count = count;
 209         buf.error = 0;
 210         buf.ctx.actor = filldir;
 211
 212         error = iterate_dir(f.file, &buf.ctx);
 213         if (error >= 0)
 214                 error = buf.error;
 215         lastdirent = buf.previous;
 216         if (lastdirent) {
 217                 if (put_user(f.file->f_pos, &lastdirent->d_off))
 218                         error = -EFAULT;
 219                 else
 220                         error = count - buf.count;
 221         }
 222         fdput(f);
 223         return error;
 224 }
 225
 226 struct getdents_callback64 {
 227         struct dir_context ctx;
 228         struct linux_dirent64 __user * current_dir;
 229         struct linux_dirent64 __user * previous;
 230         int count;
 231         int error;
 232 };
 233
 234 static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
 235                      u64 ino, unsigned int d_type)
 236 {
 237         struct linux_dirent64 __user *dirent;
 238         struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
 239         int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
 240                 sizeof(u64));
 241
 242         buf->error = -EINVAL;   /* only used if we fail.. */
 243         if (reclen > buf->count)
 244                 return -EINVAL;
 245         dirent = buf->previous;
 246         if (dirent) {
 247                 if (__put_user(offset, &dirent->d_off))
 248                         goto efault;
 249         }
 250         dirent = buf->current_dir;
 251         if (__put_user(ino, &dirent->d_ino))
 252                 goto efault;
 253         if (__put_user(0, &dirent->d_off))
 254                 goto efault;
 255         if (__put_user(reclen, &dirent->d_reclen))
 256                 goto efault;
 257         if (__put_user(d_type, &dirent->d_type))
 258                 goto efault;
 259         if (copy_to_user(dirent->d_name, name, namlen))
 260                 goto efault;
 261         if (__put_user(0, dirent->d_name + namlen))
 262                 goto efault;
 263         buf->previous = dirent;
 264         dirent = (void __user *)dirent + reclen;
 265         buf->current_dir = dirent;
 266         buf->count -= reclen;
 267         return 0;
 268 efault:
 269         buf->error = -EFAULT;
 270         return -EFAULT;
 271 }
 272
 273 SYSCALL_DEFINE3(getdents64, unsigned int, fd,
 274                 struct linux_dirent64 __user *, dirent, unsigned int, count)
 275 {
 276         struct fd f;
 277         struct linux_dirent64 __user * lastdirent;
 278         struct getdents_callback64 buf;
 279         int error;
 280
 281         if (!access_ok(VERIFY_WRITE, dirent, count))
 282                 return -EFAULT;
 283
 284         f = fdget(fd);
 285         if (!f.file)
 286                 return -EBADF;
 287
 288         buf.current_dir = dirent;
 289         buf.previous = NULL;
 290         buf.count = count;
 291         buf.error = 0;
 292         buf.ctx.actor = filldir64;
 293
 294         error = iterate_dir(f.file, &buf.ctx);
 295         if (error >= 0)
 296                 error = buf.error;
 297         lastdirent = buf.previous;
 298         if (lastdirent) {
 299                 typeof(lastdirent->d_off) d_off = f.file->f_pos;
 300                 if (__put_user(d_off, &lastdirent->d_off))
 301                         error = -EFAULT;
 302                 else
 303                         error = count - buf.count;
 304         }
 305         fdput(f);
 306         return error;
 307 }