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         mutex_lock(&inode->i_mutex);
  34         res = -ENOENT;
  35         if (!IS_DEADDIR(inode)) {
  36                 res = file->f_op->readdir(file, buf, filler);
  37                 file_accessed(file);
  38         }
  39         mutex_unlock(&inode->i_mutex);
  40 out:
  41         return res;
  42 }
  43
  44 EXPORT_SYMBOL(vfs_readdir);
  45
  46 /*
  47  * Traditional linux readdir() handling..
  48  *
  49  * "count=1" is a special case, meaning that the buffer is one
  50  * dirent-structure in size and that the code can't handle more
  51  * anyway. Thus the special "fillonedir()" function for that
  52  * case (the low-level handlers don't need to care about this).
  53  */
  54 #define NAME_OFFSET(de) ((int) ((de)->d_name - (char __user *) (de)))
  55
  56 #ifdef __ARCH_WANT_OLD_READDIR
  57
  58 struct old_linux_dirent {
  59         unsigned long   d_ino;
  60         unsigned long   d_offset;
  61         unsigned short  d_namlen;
  62         char            d_name[1];
  63 };
  64
  65 struct readdir_callback {
  66         struct old_linux_dirent __user * dirent;
  67         int result;
  68 };
  69
  70 static int fillonedir(void * __buf, const char * name, int namlen, loff_t offset,
  71                       u64 ino, unsigned int d_type)
  72 {
  73         struct readdir_callback * buf = (struct readdir_callback *) __buf;
  74         struct old_linux_dirent __user * dirent;
  75         unsigned long d_ino;
  76
  77         if (buf->result)
  78                 return -EINVAL;
  79         d_ino = ino;
  80         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino)
  81                 return -EOVERFLOW;
  82         buf->result++;
  83         dirent = buf->dirent;
  84         if (!access_ok(VERIFY_WRITE, dirent,
  85                         (unsigned long)(dirent->d_name + namlen + 1) -
  86                                 (unsigned long)dirent))
  87                 goto efault;
  88         if (    __put_user(d_ino, &dirent->d_ino) ||
  89                 __put_user(offset, &dirent->d_offset) ||
  90                 __put_user(namlen, &dirent->d_namlen) ||
  91                 __copy_to_user(dirent->d_name, name, namlen) ||
  92                 __put_user(0, dirent->d_name + namlen))
  93                 goto efault;
  94         return 0;
  95 efault:
  96         buf->result = -EFAULT;
  97         return -EFAULT;
  98 }
  99
 100 asmlinkage long old_readdir(unsigned int fd, struct old_linux_dirent __user * dirent, unsigned int count)
 101 {
 102         int error;
 103         struct file * file;
 104         struct readdir_callback buf;
 105
 106         error = -EBADF;
 107         file = fget(fd);
 108         if (!file)
 109                 goto out;
 110
 111         buf.result = 0;
 112         buf.dirent = dirent;
 113
 114         error = vfs_readdir(file, fillonedir, &buf);
 115         if (error >= 0)
 116                 error = buf.result;
 117
 118         fput(file);
 119 out:
 120         return error;
 121 }
 122
 123 #endif /* __ARCH_WANT_OLD_READDIR */
 124
 125 /*
 126  * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 127  * interface.
 128  */
 129 struct linux_dirent {
 130         unsigned long   d_ino;
 131         unsigned long   d_off;
 132         unsigned short  d_reclen;
 133         char            d_name[1];
 134 };
 135
 136 struct getdents_callback {
 137         struct linux_dirent __user * current_dir;
 138         struct linux_dirent __user * previous;
 139         int count;
 140         int error;
 141 };
 142
 143 static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
 144                    u64 ino, unsigned int d_type)
 145 {
 146         struct linux_dirent __user * dirent;
 147         struct getdents_callback * buf = (struct getdents_callback *) __buf;
 148         unsigned long d_ino;
 149         int reclen = ALIGN(NAME_OFFSET(dirent) + namlen + 2, sizeof(long));
 150
 151         buf->error = -EINVAL;   /* only used if we fail.. */
 152         if (reclen > buf->count)
 153                 return -EINVAL;
 154         d_ino = ino;
 155         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino)
 156                 return -EOVERFLOW;
 157         dirent = buf->previous;
 158         if (dirent) {
 159                 if (__put_user(offset, &dirent->d_off))
 160                         goto efault;
 161         }
 162         dirent = buf->current_dir;
 163         if (__put_user(d_ino, &dirent->d_ino))
 164                 goto efault;
 165         if (__put_user(reclen, &dirent->d_reclen))
 166                 goto efault;
 167         if (copy_to_user(dirent->d_name, name, namlen))
 168                 goto efault;
 169         if (__put_user(0, dirent->d_name + namlen))
 170                 goto efault;
 171         if (__put_user(d_type, (char __user *) dirent + reclen - 1))
 172                 goto efault;
 173         buf->previous = dirent;
 174         dirent = (void __user *)dirent + reclen;
 175         buf->current_dir = dirent;
 176         buf->count -= reclen;
 177         return 0;
 178 efault:
 179         buf->error = -EFAULT;
 180         return -EFAULT;
 181 }
 182
 183 asmlinkage long sys_getdents(unsigned int fd, struct linux_dirent __user * dirent, unsigned int count)
 184 {
 185         struct file * file;
 186         struct linux_dirent __user * lastdirent;
 187         struct getdents_callback buf;
 188         int error;
 189
 190         error = -EFAULT;
 191         if (!access_ok(VERIFY_WRITE, dirent, count))
 192                 goto out;
 193
 194         error = -EBADF;
 195         file = fget(fd);
 196         if (!file)
 197                 goto out;
 198
 199         buf.current_dir = dirent;
 200         buf.previous = NULL;
 201         buf.count = count;
 202         buf.error = 0;
 203
 204         error = vfs_readdir(file, filldir, &buf);
 205         if (error < 0)
 206                 goto out_putf;
 207         error = buf.error;
 208         lastdirent = buf.previous;
 209         if (lastdirent) {
 210                 if (put_user(file->f_pos, &lastdirent->d_off))
 211                         error = -EFAULT;
 212                 else
 213                         error = count - buf.count;
 214         }
 215
 216 out_putf:
 217         fput(file);
 218 out:
 219         return error;
 220 }
 221
 222 struct getdents_callback64 {
 223         struct linux_dirent64 __user * current_dir;
 224         struct linux_dirent64 __user * previous;
 225         int count;
 226         int error;
 227 };
 228
 229 static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
 230                      u64 ino, unsigned int d_type)
 231 {
 232         struct linux_dirent64 __user *dirent;
 233         struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
 234         int reclen = ALIGN(NAME_OFFSET(dirent) + namlen + 1, sizeof(u64));
 235
 236         buf->error = -EINVAL;   /* only used if we fail.. */
 237         if (reclen > buf->count)
 238                 return -EINVAL;
 239         dirent = buf->previous;
 240         if (dirent) {
 241                 if (__put_user(offset, &dirent->d_off))
 242                         goto efault;
 243         }
 244         dirent = buf->current_dir;
 245         if (__put_user(ino, &dirent->d_ino))
 246                 goto efault;
 247         if (__put_user(0, &dirent->d_off))
 248                 goto efault;
 249         if (__put_user(reclen, &dirent->d_reclen))
 250                 goto efault;
 251         if (__put_user(d_type, &dirent->d_type))
 252                 goto efault;
 253         if (copy_to_user(dirent->d_name, name, namlen))
 254                 goto efault;
 255         if (__put_user(0, dirent->d_name + namlen))
 256                 goto efault;
 257         buf->previous = dirent;
 258         dirent = (void __user *)dirent + reclen;
 259         buf->current_dir = dirent;
 260         buf->count -= reclen;
 261         return 0;
 262 efault:
 263         buf->error = -EFAULT;
 264         return -EFAULT;
 265 }
 266
 267 asmlinkage long sys_getdents64(unsigned int fd, struct linux_dirent64 __user * dirent, unsigned int count)
 268 {
 269         struct file * file;
 270         struct linux_dirent64 __user * lastdirent;
 271         struct getdents_callback64 buf;
 272         int error;
 273
 274         error = -EFAULT;
 275         if (!access_ok(VERIFY_WRITE, dirent, count))
 276                 goto out;
 277
 278         error = -EBADF;
 279         file = fget(fd);
 280         if (!file)
 281                 goto out;
 282
 283         buf.current_dir = dirent;
 284         buf.previous = NULL;
 285         buf.count = count;
 286         buf.error = 0;
 287
 288         error = vfs_readdir(file, filldir64, &buf);
 289         if (error < 0)
 290                 goto out_putf;
 291         error = buf.error;
 292         lastdirent = buf.previous;
 293         if (lastdirent) {
 294                 typeof(lastdirent->d_off) d_off = file->f_pos;
 295                 error = -EFAULT;
 296                 if (__put_user(d_off, &lastdirent->d_off))
 297                         goto out_putf;
 298                 error = count - buf.count;
 299         }
 300
 301 out_putf:
 302         fput(file);
 303 out:
 304         return error;
 305 }