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                 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 asmlinkage long old_readdir(unsigned int fd, struct old_linux_dirent __user * dirent, unsigned int count)
 106 {
 107         int error;
 108         struct file * file;
 109         struct readdir_callback buf;
 110
 111         error = -EBADF;
 112         file = fget(fd);
 113         if (!file)
 114                 goto out;
 115
 116         buf.result = 0;
 117         buf.dirent = dirent;
 118
 119         error = vfs_readdir(file, fillonedir, &buf);
 120         if (buf.result)
 121                 error = buf.result;
 122
 123         fput(file);
 124 out:
 125         return error;
 126 }
 127
 128 #endif /* __ARCH_WANT_OLD_READDIR */
 129
 130 /*
 131  * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 132  * interface.
 133  */
 134 struct linux_dirent {
 135         unsigned long   d_ino;
 136         unsigned long   d_off;
 137         unsigned short  d_reclen;
 138         char            d_name[1];
 139 };
 140
 141 struct getdents_callback {
 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(NAME_OFFSET(dirent) + namlen + 2, sizeof(long));
 155
 156         buf->error = -EINVAL;   /* only used if we fail.. */
 157         if (reclen > buf->count)
 158                 return -EINVAL;
 159         d_ino = ino;
 160         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
 161                 buf->error = -EOVERFLOW;
 162                 return -EOVERFLOW;
 163         }
 164         dirent = buf->previous;
 165         if (dirent) {
 166                 if (__put_user(offset, &dirent->d_off))
 167                         goto efault;
 168         }
 169         dirent = buf->current_dir;
 170         if (__put_user(d_ino, &dirent->d_ino))
 171                 goto efault;
 172         if (__put_user(reclen, &dirent->d_reclen))
 173                 goto efault;
 174         if (copy_to_user(dirent->d_name, name, namlen))
 175                 goto efault;
 176         if (__put_user(0, dirent->d_name + namlen))
 177                 goto efault;
 178         if (__put_user(d_type, (char __user *) dirent + reclen - 1))
 179                 goto efault;
 180         buf->previous = dirent;
 181         dirent = (void __user *)dirent + reclen;
 182         buf->current_dir = dirent;
 183         buf->count -= reclen;
 184         return 0;
 185 efault:
 186         buf->error = -EFAULT;
 187         return -EFAULT;
 188 }
 189
 190 asmlinkage long sys_getdents(unsigned int fd, struct linux_dirent __user * dirent, unsigned int count)
 191 {
 192         struct file * file;
 193         struct linux_dirent __user * lastdirent;
 194         struct getdents_callback buf;
 195         int error;
 196
 197         error = -EFAULT;
 198         if (!access_ok(VERIFY_WRITE, dirent, count))
 199                 goto out;
 200
 201         error = -EBADF;
 202         file = fget(fd);
 203         if (!file)
 204                 goto out;
 205
 206         buf.current_dir = dirent;
 207         buf.previous = NULL;
 208         buf.count = count;
 209         buf.error = 0;
 210
 211         error = vfs_readdir(file, filldir, &buf);
 212         if (error >= 0)
 213                 error = buf.error;
 214         lastdirent = buf.previous;
 215         if (lastdirent) {
 216                 if (put_user(file->f_pos, &lastdirent->d_off))
 217                         error = -EFAULT;
 218                 else
 219                         error = count - buf.count;
 220         }
 221         fput(file);
 222 out:
 223         return error;
 224 }
 225
 226 struct getdents_callback64 {
 227         struct linux_dirent64 __user * current_dir;
 228         struct linux_dirent64 __user * previous;
 229         int count;
 230         int error;
 231 };
 232
 233 static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
 234                      u64 ino, unsigned int d_type)
 235 {
 236         struct linux_dirent64 __user *dirent;
 237         struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
 238         int reclen = ALIGN(NAME_OFFSET(dirent) + namlen + 1, sizeof(u64));
 239
 240         buf->error = -EINVAL;   /* only used if we fail.. */
 241         if (reclen > buf->count)
 242                 return -EINVAL;
 243         dirent = buf->previous;
 244         if (dirent) {
 245                 if (__put_user(offset, &dirent->d_off))
 246                         goto efault;
 247         }
 248         dirent = buf->current_dir;
 249         if (__put_user(ino, &dirent->d_ino))
 250                 goto efault;
 251         if (__put_user(0, &dirent->d_off))
 252                 goto efault;
 253         if (__put_user(reclen, &dirent->d_reclen))
 254                 goto efault;
 255         if (__put_user(d_type, &dirent->d_type))
 256                 goto efault;
 257         if (copy_to_user(dirent->d_name, name, namlen))
 258                 goto efault;
 259         if (__put_user(0, dirent->d_name + namlen))
 260                 goto efault;
 261         buf->previous = dirent;
 262         dirent = (void __user *)dirent + reclen;
 263         buf->current_dir = dirent;
 264         buf->count -= reclen;
 265         return 0;
 266 efault:
 267         buf->error = -EFAULT;
 268         return -EFAULT;
 269 }
 270
 271 asmlinkage long sys_getdents64(unsigned int fd, struct linux_dirent64 __user * dirent, unsigned int count)
 272 {
 273         struct file * file;
 274         struct linux_dirent64 __user * lastdirent;
 275         struct getdents_callback64 buf;
 276         int error;
 277
 278         error = -EFAULT;
 279         if (!access_ok(VERIFY_WRITE, dirent, count))
 280                 goto out;
 281
 282         error = -EBADF;
 283         file = fget(fd);
 284         if (!file)
 285                 goto out;
 286
 287         buf.current_dir = dirent;
 288         buf.previous = NULL;
 289         buf.count = count;
 290         buf.error = 0;
 291
 292         error = vfs_readdir(file, filldir64, &buf);
 293         if (error >= 0)
 294                 error = buf.error;
 295         lastdirent = buf.previous;
 296         if (lastdirent) {
 297                 typeof(lastdirent->d_off) d_off = file->f_pos;
 298                 if (__put_user(d_off, &lastdirent->d_off))
 299                         error = -EFAULT;
 300                 else
 301                         error = count - buf.count;
 302         }
 303         fput(file);
 304 out:
 305         return error;
 306 }