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TOMOYO Linux Cross Reference
Linux/fs/readdir.c

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  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                 .ctx.actor = fillonedir,
114                 .dirent = dirent
115         };
116 
117         if (!f.file)
118                 return -EBADF;
119 
120         error = iterate_dir(f.file, &buf.ctx);
121         if (buf.result)
122                 error = buf.result;
123 
124         fdput(f);
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 dir_context ctx;
143         struct linux_dirent __user * current_dir;
144         struct linux_dirent __user * previous;
145         int count;
146         int error;
147 };
148 
149 static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
150                    u64 ino, unsigned int d_type)
151 {
152         struct linux_dirent __user * dirent;
153         struct getdents_callback * buf = (struct getdents_callback *) __buf;
154         unsigned long d_ino;
155         int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
156                 sizeof(long));
157 
158         buf->error = -EINVAL;   /* only used if we fail.. */
159         if (reclen > buf->count)
160                 return -EINVAL;
161         d_ino = ino;
162         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
163                 buf->error = -EOVERFLOW;
164                 return -EOVERFLOW;
165         }
166         dirent = buf->previous;
167         if (dirent) {
168                 if (__put_user(offset, &dirent->d_off))
169                         goto efault;
170         }
171         dirent = buf->current_dir;
172         if (__put_user(d_ino, &dirent->d_ino))
173                 goto efault;
174         if (__put_user(reclen, &dirent->d_reclen))
175                 goto efault;
176         if (copy_to_user(dirent->d_name, name, namlen))
177                 goto efault;
178         if (__put_user(0, dirent->d_name + namlen))
179                 goto efault;
180         if (__put_user(d_type, (char __user *) dirent + reclen - 1))
181                 goto efault;
182         buf->previous = dirent;
183         dirent = (void __user *)dirent + reclen;
184         buf->current_dir = dirent;
185         buf->count -= reclen;
186         return 0;
187 efault:
188         buf->error = -EFAULT;
189         return -EFAULT;
190 }
191 
192 SYSCALL_DEFINE3(getdents, unsigned int, fd,
193                 struct linux_dirent __user *, dirent, unsigned int, count)
194 {
195         struct fd f;
196         struct linux_dirent __user * lastdirent;
197         struct getdents_callback buf = {
198                 .ctx.actor = filldir,
199                 .count = count,
200                 .current_dir = dirent
201         };
202         int error;
203 
204         if (!access_ok(VERIFY_WRITE, dirent, count))
205                 return -EFAULT;
206 
207         f = fdget(fd);
208         if (!f.file)
209                 return -EBADF;
210 
211         error = iterate_dir(f.file, &buf.ctx);
212         if (error >= 0)
213                 error = buf.error;
214         lastdirent = buf.previous;
215         if (lastdirent) {
216                 if (put_user(buf.ctx.pos, &lastdirent->d_off))
217                         error = -EFAULT;
218                 else
219                         error = count - buf.count;
220         }
221         fdput(f);
222         return error;
223 }
224 
225 struct getdents_callback64 {
226         struct dir_context ctx;
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(offsetof(struct linux_dirent64, d_name) + namlen + 1,
239                 sizeof(u64));
240 
241         buf->error = -EINVAL;   /* only used if we fail.. */
242         if (reclen > buf->count)
243                 return -EINVAL;
244         dirent = buf->previous;
245         if (dirent) {
246                 if (__put_user(offset, &dirent->d_off))
247                         goto efault;
248         }
249         dirent = buf->current_dir;
250         if (__put_user(ino, &dirent->d_ino))
251                 goto efault;
252         if (__put_user(0, &dirent->d_off))
253                 goto efault;
254         if (__put_user(reclen, &dirent->d_reclen))
255                 goto efault;
256         if (__put_user(d_type, &dirent->d_type))
257                 goto efault;
258         if (copy_to_user(dirent->d_name, name, namlen))
259                 goto efault;
260         if (__put_user(0, dirent->d_name + namlen))
261                 goto efault;
262         buf->previous = dirent;
263         dirent = (void __user *)dirent + reclen;
264         buf->current_dir = dirent;
265         buf->count -= reclen;
266         return 0;
267 efault:
268         buf->error = -EFAULT;
269         return -EFAULT;
270 }
271 
272 SYSCALL_DEFINE3(getdents64, unsigned int, fd,
273                 struct linux_dirent64 __user *, dirent, unsigned int, count)
274 {
275         struct fd f;
276         struct linux_dirent64 __user * lastdirent;
277         struct getdents_callback64 buf = {
278                 .ctx.actor = filldir64,
279                 .count = count,
280                 .current_dir = dirent
281         };
282         int error;
283 
284         if (!access_ok(VERIFY_WRITE, dirent, count))
285                 return -EFAULT;
286 
287         f = fdget(fd);
288         if (!f.file)
289                 return -EBADF;
290 
291         error = iterate_dir(f.file, &buf.ctx);
292         if (error >= 0)
293                 error = buf.error;
294         lastdirent = buf.previous;
295         if (lastdirent) {
296                 typeof(lastdirent->d_off) d_off = buf.ctx.pos;
297                 if (__put_user(d_off, &lastdirent->d_off))
298                         error = -EFAULT;
299                 else
300                         error = count - buf.count;
301         }
302         fdput(f);
303         return error;
304 }
305 

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