fs/readdir.c

   1 /*
   2  *  linux/fs/readdir.c
   3  *
   4  *  Copyright (C) 1995  Linus Torvalds
   5  */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/module.h>
   9 #include <linux/time.h>
  10 #include <linux/mm.h>
  11 #include <linux/errno.h>
  12 #include <linux/stat.h>
  13 #include <linux/file.h>
  14 #include <linux/fs.h>
  15 #include <linux/dirent.h>
  16 #include <linux/security.h>
  17 #include <linux/syscalls.h>
  18 #include <linux/unistd.h>
  19
  20 #include <asm/uaccess.h>
  21
  22 int vfs_readdir(struct file *file, filldir_t filler, void *buf)
  23 {
  24         struct inode *inode = file->f_path.dentry->d_inode;
  25         int res = -ENOTDIR;
  26         if (!file->f_op || !file->f_op->readdir)
  27                 goto out;
  28
  29         res = security_file_permission(file, MAY_READ);
  30         if (res)
  31                 goto out;
  32
  33         res = mutex_lock_killable(&inode->i_mutex);
  34         if (res)
  35                 goto out;
  36
  37         res = -ENOENT;
  38         if (!IS_DEADDIR(inode)) {
  39                 res = file->f_op->readdir(file, buf, filler);
  40                 file_accessed(file);
  41         }
  42         mutex_unlock(&inode->i_mutex);
  43 out:
  44         return res;
  45 }
  46
  47 EXPORT_SYMBOL(vfs_readdir);
  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 #define NAME_OFFSET(de) ((int) ((de)->d_name - (char __user *) (de)))
  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                 return -EOVERFLOW;
  85         buf->result++;
  86         dirent = buf->dirent;
  87         if (!access_ok(VERIFY_WRITE, dirent,
  88                         (unsigned long)(dirent->d_name + namlen + 1) -
  89                                 (unsigned long)dirent))
  90                 goto efault;
  91         if (    __put_user(d_ino, &dirent->d_ino) ||
  92                 __put_user(offset, &dirent->d_offset) ||
  93                 __put_user(namlen, &dirent->d_namlen) ||
  94                 __copy_to_user(dirent->d_name, name, namlen) ||
  95                 __put_user(0, dirent->d_name + namlen))
  96                 goto efault;
  97         return 0;
  98 efault:
  99         buf->result = -EFAULT;
 100         return -EFAULT;
 101 }
 102
 103 asmlinkage long old_readdir(unsigned int fd, struct old_linux_dirent __user * dirent, unsigned int count)
 104 {
 105         int error;
 106         struct file * file;
 107         struct readdir_callback buf;
 108
 109         error = -EBADF;
 110         file = fget(fd);
 111         if (!file)
 112                 goto out;
 113
 114         buf.result = 0;
 115         buf.dirent = dirent;
 116
 117         error = vfs_readdir(file, fillonedir, &buf);
 118         if (error >= 0)
 119                 error = buf.result;
 120
 121         fput(file);
 122 out:
 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(NAME_OFFSET(dirent) + namlen + 2, sizeof(long));
 153
 154         buf->error = -EINVAL;   /* only used if we fail.. */
 155         if (reclen > buf->count)
 156                 return -EINVAL;
 157         d_ino = ino;
 158         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino)
 159                 return -EOVERFLOW;
 160         dirent = buf->previous;
 161         if (dirent) {
 162                 if (__put_user(offset, &dirent->d_off))
 163                         goto efault;
 164         }
 165         dirent = buf->current_dir;
 166         if (__put_user(d_ino, &dirent->d_ino))
 167                 goto efault;
 168         if (__put_user(reclen, &dirent->d_reclen))
 169                 goto efault;
 170         if (copy_to_user(dirent->d_name, name, namlen))
 171                 goto efault;
 172         if (__put_user(0, dirent->d_name + namlen))
 173                 goto efault;
 174         if (__put_user(d_type, (char __user *) dirent + reclen - 1))
 175                 goto efault;
 176         buf->previous = dirent;
 177         dirent = (void __user *)dirent + reclen;
 178         buf->current_dir = dirent;
 179         buf->count -= reclen;
 180         return 0;
 181 efault:
 182         buf->error = -EFAULT;
 183         return -EFAULT;
 184 }
 185
 186 asmlinkage long sys_getdents(unsigned int fd, struct linux_dirent __user * dirent, unsigned int count)
 187 {
 188         struct file * file;
 189         struct linux_dirent __user * lastdirent;
 190         struct getdents_callback buf;
 191         int error;
 192
 193         error = -EFAULT;
 194         if (!access_ok(VERIFY_WRITE, dirent, count))
 195                 goto out;
 196
 197         error = -EBADF;
 198         file = fget(fd);
 199         if (!file)
 200                 goto out;
 201
 202         buf.current_dir = dirent;
 203         buf.previous = NULL;
 204         buf.count = count;
 205         buf.error = 0;
 206
 207         error = vfs_readdir(file, filldir, &buf);
 208         if (error < 0)
 209                 goto out_putf;
 210         error = buf.error;
 211         lastdirent = buf.previous;
 212         if (lastdirent) {
 213                 if (put_user(file->f_pos, &lastdirent->d_off))
 214                         error = -EFAULT;
 215                 else
 216                         error = count - buf.count;
 217         }
 218
 219 out_putf:
 220         fput(file);
 221 out:
 222         return error;
 223 }
 224
 225 struct getdents_callback64 {
 226         struct linux_dirent64 __user * current_dir;
 227         struct linux_dirent64 __user * previous;
 228         int count;
 229         int error;
 230 };
 231
 232 static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
 233                      u64 ino, unsigned int d_type)
 234 {
 235         struct linux_dirent64 __user *dirent;
 236         struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
 237         int reclen = ALIGN(NAME_OFFSET(dirent) + namlen + 1, sizeof(u64));
 238
 239         buf->error = -EINVAL;   /* only used if we fail.. */
 240         if (reclen > buf->count)
 241                 return -EINVAL;
 242         dirent = buf->previous;
 243         if (dirent) {
 244                 if (__put_user(offset, &dirent->d_off))
 245                         goto efault;
 246         }
 247         dirent = buf->current_dir;
 248         if (__put_user(ino, &dirent->d_ino))
 249                 goto efault;
 250         if (__put_user(0, &dirent->d_off))
 251                 goto efault;
 252         if (__put_user(reclen, &dirent->d_reclen))
 253                 goto efault;
 254         if (__put_user(d_type, &dirent->d_type))
 255                 goto efault;
 256         if (copy_to_user(dirent->d_name, name, namlen))
 257                 goto efault;
 258         if (__put_user(0, dirent->d_name + namlen))
 259                 goto efault;
 260         buf->previous = dirent;
 261         dirent = (void __user *)dirent + reclen;
 262         buf->current_dir = dirent;
 263         buf->count -= reclen;
 264         return 0;
 265 efault:
 266         buf->error = -EFAULT;
 267         return -EFAULT;
 268 }
 269
 270 asmlinkage long sys_getdents64(unsigned int fd, struct linux_dirent64 __user * dirent, unsigned int count)
 271 {
 272         struct file * file;
 273         struct linux_dirent64 __user * lastdirent;
 274         struct getdents_callback64 buf;
 275         int error;
 276
 277         error = -EFAULT;
 278         if (!access_ok(VERIFY_WRITE, dirent, count))
 279                 goto out;
 280
 281         error = -EBADF;
 282         file = fget(fd);
 283         if (!file)
 284                 goto out;
 285
 286         buf.current_dir = dirent;
 287         buf.previous = NULL;
 288         buf.count = count;
 289         buf.error = 0;
 290
 291         error = vfs_readdir(file, filldir64, &buf);
 292         if (error < 0)
 293                 goto out_putf;
 294         error = buf.error;
 295         lastdirent = buf.previous;
 296         if (lastdirent) {
 297                 typeof(lastdirent->d_off) d_off = file->f_pos;
 298                 error = -EFAULT;
 299                 if (__put_user(d_off, &lastdirent->d_off))
 300                         goto out_putf;
 301                 error = count - buf.count;
 302         }
 303
 304 out_putf:
 305         fput(file);
 306 out:
 307         return error;
 308 }