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 vfs_readdir(struct file *file, filldir_t filler, void *buf)
  24 {
  25         struct inode *inode = file->f_path.dentry->d_inode;
  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, buf, filler);
  41                 file_accessed(file);
  42         }
  43         mutex_unlock(&inode->i_mutex);
  44 out:
  45         return res;
  46 }
  47
  48 EXPORT_SYMBOL(vfs_readdir);
  49
  50 /*
  51  * Traditional linux readdir() handling..
  52  *
  53  * "count=1" is a special case, meaning that the buffer is one
  54  * dirent-structure in size and that the code can't handle more
  55  * anyway. Thus the special "fillonedir()" function for that
  56  * case (the low-level handlers don't need to care about this).
  57  */
  58
  59 #ifdef __ARCH_WANT_OLD_READDIR
  60
  61 struct old_linux_dirent {
  62         unsigned long   d_ino;
  63         unsigned long   d_offset;
  64         unsigned short  d_namlen;
  65         char            d_name[1];
  66 };
  67
  68 struct readdir_callback {
  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 file * file;
 110         struct readdir_callback buf;
 111
 112         error = -EBADF;
 113         file = fget(fd);
 114         if (!file)
 115                 goto out;
 116
 117         buf.result = 0;
 118         buf.dirent = dirent;
 119
 120         error = vfs_readdir(file, fillonedir, &buf);
 121         if (buf.result)
 122                 error = buf.result;
 123
 124         fput(file);
 125 out:
 126         return error;
 127 }
 128
 129 #endif /* __ARCH_WANT_OLD_READDIR */
 130
 131 /*
 132  * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 133  * interface.
 134  */
 135 struct linux_dirent {
 136         unsigned long   d_ino;
 137         unsigned long   d_off;
 138         unsigned short  d_reclen;
 139         char            d_name[1];
 140 };
 141
 142 struct getdents_callback {
 143         struct linux_dirent __user * current_dir;
 144         struct linux_dirent __user * previous;
 145         int count;
 146         int error;
 147 };
 148
 149 static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
 150                    u64 ino, unsigned int d_type)
 151 {
 152         struct linux_dirent __user * dirent;
 153         struct getdents_callback * buf = (struct getdents_callback *) __buf;
 154         unsigned long d_ino;
 155         int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
 156                 sizeof(long));
 157
 158         buf->error = -EINVAL;   /* only used if we fail.. */
 159         if (reclen > buf->count)
 160                 return -EINVAL;
 161         d_ino = ino;
 162         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
 163                 buf->error = -EOVERFLOW;
 164                 return -EOVERFLOW;
 165         }
 166         dirent = buf->previous;
 167         if (dirent) {
 168                 if (__put_user(offset, &dirent->d_off))
 169                         goto efault;
 170         }
 171         dirent = buf->current_dir;
 172         if (__put_user(d_ino, &dirent->d_ino))
 173                 goto efault;
 174         if (__put_user(reclen, &dirent->d_reclen))
 175                 goto efault;
 176         if (copy_to_user(dirent->d_name, name, namlen))
 177                 goto efault;
 178         if (__put_user(0, dirent->d_name + namlen))
 179                 goto efault;
 180         if (__put_user(d_type, (char __user *) dirent + reclen - 1))
 181                 goto efault;
 182         buf->previous = dirent;
 183         dirent = (void __user *)dirent + reclen;
 184         buf->current_dir = dirent;
 185         buf->count -= reclen;
 186         return 0;
 187 efault:
 188         buf->error = -EFAULT;
 189         return -EFAULT;
 190 }
 191
 192 SYSCALL_DEFINE3(getdents, unsigned int, fd,
 193                 struct linux_dirent __user *, dirent, unsigned int, count)
 194 {
 195         struct file * file;
 196         struct linux_dirent __user * lastdirent;
 197         struct getdents_callback buf;
 198         int error;
 199
 200         error = -EFAULT;
 201         if (!access_ok(VERIFY_WRITE, dirent, count))
 202                 goto out;
 203
 204         error = -EBADF;
 205         file = fget(fd);
 206         if (!file)
 207                 goto out;
 208
 209         buf.current_dir = dirent;
 210         buf.previous = NULL;
 211         buf.count = count;
 212         buf.error = 0;
 213
 214         error = vfs_readdir(file, filldir, &buf);
 215         if (error >= 0)
 216                 error = buf.error;
 217         lastdirent = buf.previous;
 218         if (lastdirent) {
 219                 if (put_user(file->f_pos, &lastdirent->d_off))
 220                         error = -EFAULT;
 221                 else
 222                         error = count - buf.count;
 223         }
 224         fput(file);
 225 out:
 226         return error;
 227 }
 228
 229 struct getdents_callback64 {
 230         struct linux_dirent64 __user * current_dir;
 231         struct linux_dirent64 __user * previous;
 232         int count;
 233         int error;
 234 };
 235
 236 static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
 237                      u64 ino, unsigned int d_type)
 238 {
 239         struct linux_dirent64 __user *dirent;
 240         struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
 241         int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
 242                 sizeof(u64));
 243
 244         buf->error = -EINVAL;   /* only used if we fail.. */
 245         if (reclen > buf->count)
 246                 return -EINVAL;
 247         dirent = buf->previous;
 248         if (dirent) {
 249                 if (__put_user(offset, &dirent->d_off))
 250                         goto efault;
 251         }
 252         dirent = buf->current_dir;
 253         if (__put_user(ino, &dirent->d_ino))
 254                 goto efault;
 255         if (__put_user(0, &dirent->d_off))
 256                 goto efault;
 257         if (__put_user(reclen, &dirent->d_reclen))
 258                 goto efault;
 259         if (__put_user(d_type, &dirent->d_type))
 260                 goto efault;
 261         if (copy_to_user(dirent->d_name, name, namlen))
 262                 goto efault;
 263         if (__put_user(0, dirent->d_name + namlen))
 264                 goto efault;
 265         buf->previous = dirent;
 266         dirent = (void __user *)dirent + reclen;
 267         buf->current_dir = dirent;
 268         buf->count -= reclen;
 269         return 0;
 270 efault:
 271         buf->error = -EFAULT;
 272         return -EFAULT;
 273 }
 274
 275 SYSCALL_DEFINE3(getdents64, unsigned int, fd,
 276                 struct linux_dirent64 __user *, dirent, unsigned int, count)
 277 {
 278         struct file * file;
 279         struct linux_dirent64 __user * lastdirent;
 280         struct getdents_callback64 buf;
 281         int error;
 282
 283         error = -EFAULT;
 284         if (!access_ok(VERIFY_WRITE, dirent, count))
 285                 goto out;
 286
 287         error = -EBADF;
 288         file = fget(fd);
 289         if (!file)
 290                 goto out;
 291
 292         buf.current_dir = dirent;
 293         buf.previous = NULL;
 294         buf.count = count;
 295         buf.error = 0;
 296
 297         error = vfs_readdir(file, filldir64, &buf);
 298         if (error >= 0)
 299                 error = buf.error;
 300         lastdirent = buf.previous;
 301         if (lastdirent) {
 302                 typeof(lastdirent->d_off) d_off = file->f_pos;
 303                 if (__put_user(d_off, &lastdirent->d_off))
 304                         error = -EFAULT;
 305                 else
 306                         error = count - buf.count;
 307         }
 308         fput(file);
 309 out:
 310         return error;
 311 }