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_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, 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 fd f = fdget(fd);
 110         struct readdir_callback buf;
 111
 112         if (!f.file)
 113                 return -EBADF;
 114
 115         buf.result = 0;
 116         buf.dirent = dirent;
 117
 118         error = vfs_readdir(f.file, fillonedir, &buf);
 119         if (buf.result)
 120                 error = buf.result;
 121
 122         fdput(f);
 123         return error;
 124 }
 125
 126 #endif /* __ARCH_WANT_OLD_READDIR */
 127
 128 /*
 129  * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 130  * interface.
 131  */
 132 struct linux_dirent {
 133         unsigned long   d_ino;
 134         unsigned long   d_off;
 135         unsigned short  d_reclen;
 136         char            d_name[1];
 137 };
 138
 139 struct getdents_callback {
 140         struct linux_dirent __user * current_dir;
 141         struct linux_dirent __user * previous;
 142         int count;
 143         int error;
 144 };
 145
 146 static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
 147                    u64 ino, unsigned int d_type)
 148 {
 149         struct linux_dirent __user * dirent;
 150         struct getdents_callback * buf = (struct getdents_callback *) __buf;
 151         unsigned long d_ino;
 152         int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
 153                 sizeof(long));
 154
 155         buf->error = -EINVAL;   /* only used if we fail.. */
 156         if (reclen > buf->count)
 157                 return -EINVAL;
 158         d_ino = ino;
 159         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
 160                 buf->error = -EOVERFLOW;
 161                 return -EOVERFLOW;
 162         }
 163         dirent = buf->previous;
 164         if (dirent) {
 165                 if (__put_user(offset, &dirent->d_off))
 166                         goto efault;
 167         }
 168         dirent = buf->current_dir;
 169         if (__put_user(d_ino, &dirent->d_ino))
 170                 goto efault;
 171         if (__put_user(reclen, &dirent->d_reclen))
 172                 goto efault;
 173         if (copy_to_user(dirent->d_name, name, namlen))
 174                 goto efault;
 175         if (__put_user(0, dirent->d_name + namlen))
 176                 goto efault;
 177         if (__put_user(d_type, (char __user *) dirent + reclen - 1))
 178                 goto efault;
 179         buf->previous = dirent;
 180         dirent = (void __user *)dirent + reclen;
 181         buf->current_dir = dirent;
 182         buf->count -= reclen;
 183         return 0;
 184 efault:
 185         buf->error = -EFAULT;
 186         return -EFAULT;
 187 }
 188
 189 SYSCALL_DEFINE3(getdents, unsigned int, fd,
 190                 struct linux_dirent __user *, dirent, unsigned int, count)
 191 {
 192         struct fd f;
 193         struct linux_dirent __user * lastdirent;
 194         struct getdents_callback buf;
 195         int error;
 196
 197         if (!access_ok(VERIFY_WRITE, dirent, count))
 198                 return -EFAULT;
 199
 200         f = fdget(fd);
 201         if (!f.file)
 202                 return -EBADF;
 203
 204         buf.current_dir = dirent;
 205         buf.previous = NULL;
 206         buf.count = count;
 207         buf.error = 0;
 208
 209         error = vfs_readdir(f.file, filldir, &buf);
 210         if (error >= 0)
 211                 error = buf.error;
 212         lastdirent = buf.previous;
 213         if (lastdirent) {
 214                 if (put_user(f.file->f_pos, &lastdirent->d_off))
 215                         error = -EFAULT;
 216                 else
 217                         error = count - buf.count;
 218         }
 219         fdput(f);
 220         return error;
 221 }
 222
 223 struct getdents_callback64 {
 224         struct linux_dirent64 __user * current_dir;
 225         struct linux_dirent64 __user * previous;
 226         int count;
 227         int error;
 228 };
 229
 230 static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
 231                      u64 ino, unsigned int d_type)
 232 {
 233         struct linux_dirent64 __user *dirent;
 234         struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
 235         int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
 236                 sizeof(u64));
 237
 238         buf->error = -EINVAL;   /* only used if we fail.. */
 239         if (reclen > buf->count)
 240                 return -EINVAL;
 241         dirent = buf->previous;
 242         if (dirent) {
 243                 if (__put_user(offset, &dirent->d_off))
 244                         goto efault;
 245         }
 246         dirent = buf->current_dir;
 247         if (__put_user(ino, &dirent->d_ino))
 248                 goto efault;
 249         if (__put_user(0, &dirent->d_off))
 250                 goto efault;
 251         if (__put_user(reclen, &dirent->d_reclen))
 252                 goto efault;
 253         if (__put_user(d_type, &dirent->d_type))
 254                 goto efault;
 255         if (copy_to_user(dirent->d_name, name, namlen))
 256                 goto efault;
 257         if (__put_user(0, dirent->d_name + namlen))
 258                 goto efault;
 259         buf->previous = dirent;
 260         dirent = (void __user *)dirent + reclen;
 261         buf->current_dir = dirent;
 262         buf->count -= reclen;
 263         return 0;
 264 efault:
 265         buf->error = -EFAULT;
 266         return -EFAULT;
 267 }
 268
 269 SYSCALL_DEFINE3(getdents64, unsigned int, fd,
 270                 struct linux_dirent64 __user *, dirent, unsigned int, count)
 271 {
 272         struct fd f;
 273         struct linux_dirent64 __user * lastdirent;
 274         struct getdents_callback64 buf;
 275         int error;
 276
 277         if (!access_ok(VERIFY_WRITE, dirent, count))
 278                 return -EFAULT;
 279
 280         f = fdget(fd);
 281         if (!f.file)
 282                 return -EBADF;
 283
 284         buf.current_dir = dirent;
 285         buf.previous = NULL;
 286         buf.count = count;
 287         buf.error = 0;
 288
 289         error = vfs_readdir(f.file, filldir64, &buf);
 290         if (error >= 0)
 291                 error = buf.error;
 292         lastdirent = buf.previous;
 293         if (lastdirent) {
 294                 typeof(lastdirent->d_off) d_off = f.file->f_pos;
 295                 if (__put_user(d_off, &lastdirent->d_off))
 296                         error = -EFAULT;
 297                 else
 298                         error = count - buf.count;
 299         }
 300         fdput(f);
 301         return error;
 302 }