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 iterate_dir(struct file *file, struct dir_context *ctx)
  24 {
  25         struct inode *inode = file_inode(file);
  26         int res = -ENOTDIR;
  27         if (!file->f_op || !file->f_op->iterate)
  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                 ctx->pos = file->f_pos;
  41                 res = file->f_op->iterate(file, ctx);
  42                 file->f_pos = ctx->pos;
  43                 file_accessed(file);
  44         }
  45         mutex_unlock(&inode->i_mutex);
  46 out:
  47         return res;
  48 }
  49 EXPORT_SYMBOL(iterate_dir);
  50
  51 /*
  52  * Traditional linux readdir() handling..
  53  *
  54  * "count=1" is a special case, meaning that the buffer is one
  55  * dirent-structure in size and that the code can't handle more
  56  * anyway. Thus the special "fillonedir()" function for that
  57  * case (the low-level handlers don't need to care about this).
  58  */
  59
  60 #ifdef __ARCH_WANT_OLD_READDIR
  61
  62 struct old_linux_dirent {
  63         unsigned long   d_ino;
  64         unsigned long   d_offset;
  65         unsigned short  d_namlen;
  66         char            d_name[1];
  67 };
  68
  69 struct readdir_callback {
  70         struct dir_context ctx;
  71         struct old_linux_dirent __user * dirent;
  72         int result;
  73 };
  74
  75 static int fillonedir(void * __buf, const char * name, int namlen, loff_t offset,
  76                       u64 ino, unsigned int d_type)
  77 {
  78         struct readdir_callback *buf = (struct readdir_callback *) __buf;
  79         struct old_linux_dirent __user * dirent;
  80         unsigned long d_ino;
  81
  82         if (buf->result)
  83                 return -EINVAL;
  84         d_ino = ino;
  85         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
  86                 buf->result = -EOVERFLOW;
  87                 return -EOVERFLOW;
  88         }
  89         buf->result++;
  90         dirent = buf->dirent;
  91         if (!access_ok(VERIFY_WRITE, dirent,
  92                         (unsigned long)(dirent->d_name + namlen + 1) -
  93                                 (unsigned long)dirent))
  94                 goto efault;
  95         if (    __put_user(d_ino, &dirent->d_ino) ||
  96                 __put_user(offset, &dirent->d_offset) ||
  97                 __put_user(namlen, &dirent->d_namlen) ||
  98                 __copy_to_user(dirent->d_name, name, namlen) ||
  99                 __put_user(0, dirent->d_name + namlen))
 100                 goto efault;
 101         return 0;
 102 efault:
 103         buf->result = -EFAULT;
 104         return -EFAULT;
 105 }
 106
 107 SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
 108                 struct old_linux_dirent __user *, dirent, unsigned int, count)
 109 {
 110         int error;
 111         struct fd f = fdget(fd);
 112         struct readdir_callback buf;
 113
 114         if (!f.file)
 115                 return -EBADF;
 116
 117         buf.ctx.actor = fillonedir;
 118         buf.result = 0;
 119         buf.dirent = dirent;
 120
 121         error = iterate_dir(f.file, &buf.ctx);
 122         if (buf.result)
 123                 error = buf.result;
 124
 125         fdput(f);
 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 dir_context ctx;
 144         struct linux_dirent __user * current_dir;
 145         struct linux_dirent __user * previous;
 146         int count;
 147         int error;
 148 };
 149
 150 static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
 151                    u64 ino, unsigned int d_type)
 152 {
 153         struct linux_dirent __user * dirent;
 154         struct getdents_callback * buf = (struct getdents_callback *) __buf;
 155         unsigned long d_ino;
 156         int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
 157                 sizeof(long));
 158
 159         buf->error = -EINVAL;   /* only used if we fail.. */
 160         if (reclen > buf->count)
 161                 return -EINVAL;
 162         d_ino = ino;
 163         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
 164                 buf->error = -EOVERFLOW;
 165                 return -EOVERFLOW;
 166         }
 167         dirent = buf->previous;
 168         if (dirent) {
 169                 if (__put_user(offset, &dirent->d_off))
 170                         goto efault;
 171         }
 172         dirent = buf->current_dir;
 173         if (__put_user(d_ino, &dirent->d_ino))
 174                 goto efault;
 175         if (__put_user(reclen, &dirent->d_reclen))
 176                 goto efault;
 177         if (copy_to_user(dirent->d_name, name, namlen))
 178                 goto efault;
 179         if (__put_user(0, dirent->d_name + namlen))
 180                 goto efault;
 181         if (__put_user(d_type, (char __user *) dirent + reclen - 1))
 182                 goto efault;
 183         buf->previous = dirent;
 184         dirent = (void __user *)dirent + reclen;
 185         buf->current_dir = dirent;
 186         buf->count -= reclen;
 187         return 0;
 188 efault:
 189         buf->error = -EFAULT;
 190         return -EFAULT;
 191 }
 192
 193 SYSCALL_DEFINE3(getdents, unsigned int, fd,
 194                 struct linux_dirent __user *, dirent, unsigned int, count)
 195 {
 196         struct fd f;
 197         struct linux_dirent __user * lastdirent;
 198         struct getdents_callback buf;
 199         int error;
 200
 201         if (!access_ok(VERIFY_WRITE, dirent, count))
 202                 return -EFAULT;
 203
 204         f = fdget(fd);
 205         if (!f.file)
 206                 return -EBADF;
 207
 208         buf.current_dir = dirent;
 209         buf.previous = NULL;
 210         buf.count = count;
 211         buf.error = 0;
 212         buf.ctx.actor = filldir;
 213
 214         error = iterate_dir(f.file, &buf.ctx);
 215         if (error >= 0)
 216                 error = buf.error;
 217         lastdirent = buf.previous;
 218         if (lastdirent) {
 219                 if (put_user(buf.ctx.pos, &lastdirent->d_off))
 220                         error = -EFAULT;
 221                 else
 222                         error = count - buf.count;
 223         }
 224         fdput(f);
 225         return error;
 226 }
 227
 228 struct getdents_callback64 {
 229         struct dir_context ctx;
 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 fd f;
 279         struct linux_dirent64 __user * lastdirent;
 280         struct getdents_callback64 buf;
 281         int error;
 282
 283         if (!access_ok(VERIFY_WRITE, dirent, count))
 284                 return -EFAULT;
 285
 286         f = fdget(fd);
 287         if (!f.file)
 288                 return -EBADF;
 289
 290         buf.current_dir = dirent;
 291         buf.previous = NULL;
 292         buf.count = count;
 293         buf.error = 0;
 294         buf.ctx.actor = filldir64;
 295
 296         error = iterate_dir(f.file, &buf.ctx);
 297         if (error >= 0)
 298                 error = buf.error;
 299         lastdirent = buf.previous;
 300         if (lastdirent) {
 301                 typeof(lastdirent->d_off) d_off = buf.ctx.pos;
 302                 if (__put_user(d_off, &lastdirent->d_off))
 303                         error = -EFAULT;
 304                 else
 305                         error = count - buf.count;
 306         }
 307         fdput(f);
 308         return error;
 309 }