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TOMOYO Linux Cross Reference
Linux/fs/statfs.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 #include <linux/syscalls.h>
  3 #include <linux/export.h>
  4 #include <linux/fs.h>
  5 #include <linux/file.h>
  6 #include <linux/mount.h>
  7 #include <linux/namei.h>
  8 #include <linux/statfs.h>
  9 #include <linux/security.h>
 10 #include <linux/uaccess.h>
 11 #include <linux/compat.h>
 12 #include "internal.h"
 13 
 14 static int flags_by_mnt(int mnt_flags)
 15 {
 16         int flags = 0;
 17 
 18         if (mnt_flags & MNT_READONLY)
 19                 flags |= ST_RDONLY;
 20         if (mnt_flags & MNT_NOSUID)
 21                 flags |= ST_NOSUID;
 22         if (mnt_flags & MNT_NODEV)
 23                 flags |= ST_NODEV;
 24         if (mnt_flags & MNT_NOEXEC)
 25                 flags |= ST_NOEXEC;
 26         if (mnt_flags & MNT_NOATIME)
 27                 flags |= ST_NOATIME;
 28         if (mnt_flags & MNT_NODIRATIME)
 29                 flags |= ST_NODIRATIME;
 30         if (mnt_flags & MNT_RELATIME)
 31                 flags |= ST_RELATIME;
 32         return flags;
 33 }
 34 
 35 static int flags_by_sb(int s_flags)
 36 {
 37         int flags = 0;
 38         if (s_flags & SB_SYNCHRONOUS)
 39                 flags |= ST_SYNCHRONOUS;
 40         if (s_flags & SB_MANDLOCK)
 41                 flags |= ST_MANDLOCK;
 42         if (s_flags & SB_RDONLY)
 43                 flags |= ST_RDONLY;
 44         return flags;
 45 }
 46 
 47 static int calculate_f_flags(struct vfsmount *mnt)
 48 {
 49         return ST_VALID | flags_by_mnt(mnt->mnt_flags) |
 50                 flags_by_sb(mnt->mnt_sb->s_flags);
 51 }
 52 
 53 static int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf)
 54 {
 55         int retval;
 56 
 57         if (!dentry->d_sb->s_op->statfs)
 58                 return -ENOSYS;
 59 
 60         memset(buf, 0, sizeof(*buf));
 61         retval = security_sb_statfs(dentry);
 62         if (retval)
 63                 return retval;
 64         retval = dentry->d_sb->s_op->statfs(dentry, buf);
 65         if (retval == 0 && buf->f_frsize == 0)
 66                 buf->f_frsize = buf->f_bsize;
 67         return retval;
 68 }
 69 
 70 int vfs_statfs(const struct path *path, struct kstatfs *buf)
 71 {
 72         int error;
 73 
 74         error = statfs_by_dentry(path->dentry, buf);
 75         if (!error)
 76                 buf->f_flags = calculate_f_flags(path->mnt);
 77         return error;
 78 }
 79 EXPORT_SYMBOL(vfs_statfs);
 80 
 81 int user_statfs(const char __user *pathname, struct kstatfs *st)
 82 {
 83         struct path path;
 84         int error;
 85         unsigned int lookup_flags = LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT;
 86 retry:
 87         error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
 88         if (!error) {
 89                 error = vfs_statfs(&path, st);
 90                 path_put(&path);
 91                 if (retry_estale(error, lookup_flags)) {
 92                         lookup_flags |= LOOKUP_REVAL;
 93                         goto retry;
 94                 }
 95         }
 96         return error;
 97 }
 98 
 99 int fd_statfs(int fd, struct kstatfs *st)
100 {
101         struct fd f = fdget_raw(fd);
102         int error = -EBADF;
103         if (f.file) {
104                 error = vfs_statfs(&f.file->f_path, st);
105                 fdput(f);
106         }
107         return error;
108 }
109 
110 static int do_statfs_native(struct kstatfs *st, struct statfs __user *p)
111 {
112         struct statfs buf;
113 
114         if (sizeof(buf) == sizeof(*st))
115                 memcpy(&buf, st, sizeof(*st));
116         else {
117                 if (sizeof buf.f_blocks == 4) {
118                         if ((st->f_blocks | st->f_bfree | st->f_bavail |
119                              st->f_bsize | st->f_frsize) &
120                             0xffffffff00000000ULL)
121                                 return -EOVERFLOW;
122                         /*
123                          * f_files and f_ffree may be -1; it's okay to stuff
124                          * that into 32 bits
125                          */
126                         if (st->f_files != -1 &&
127                             (st->f_files & 0xffffffff00000000ULL))
128                                 return -EOVERFLOW;
129                         if (st->f_ffree != -1 &&
130                             (st->f_ffree & 0xffffffff00000000ULL))
131                                 return -EOVERFLOW;
132                 }
133 
134                 buf.f_type = st->f_type;
135                 buf.f_bsize = st->f_bsize;
136                 buf.f_blocks = st->f_blocks;
137                 buf.f_bfree = st->f_bfree;
138                 buf.f_bavail = st->f_bavail;
139                 buf.f_files = st->f_files;
140                 buf.f_ffree = st->f_ffree;
141                 buf.f_fsid = st->f_fsid;
142                 buf.f_namelen = st->f_namelen;
143                 buf.f_frsize = st->f_frsize;
144                 buf.f_flags = st->f_flags;
145                 memset(buf.f_spare, 0, sizeof(buf.f_spare));
146         }
147         if (copy_to_user(p, &buf, sizeof(buf)))
148                 return -EFAULT;
149         return 0;
150 }
151 
152 static int do_statfs64(struct kstatfs *st, struct statfs64 __user *p)
153 {
154         struct statfs64 buf;
155         if (sizeof(buf) == sizeof(*st))
156                 memcpy(&buf, st, sizeof(*st));
157         else {
158                 buf.f_type = st->f_type;
159                 buf.f_bsize = st->f_bsize;
160                 buf.f_blocks = st->f_blocks;
161                 buf.f_bfree = st->f_bfree;
162                 buf.f_bavail = st->f_bavail;
163                 buf.f_files = st->f_files;
164                 buf.f_ffree = st->f_ffree;
165                 buf.f_fsid = st->f_fsid;
166                 buf.f_namelen = st->f_namelen;
167                 buf.f_frsize = st->f_frsize;
168                 buf.f_flags = st->f_flags;
169                 memset(buf.f_spare, 0, sizeof(buf.f_spare));
170         }
171         if (copy_to_user(p, &buf, sizeof(buf)))
172                 return -EFAULT;
173         return 0;
174 }
175 
176 SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
177 {
178         struct kstatfs st;
179         int error = user_statfs(pathname, &st);
180         if (!error)
181                 error = do_statfs_native(&st, buf);
182         return error;
183 }
184 
185 SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
186 {
187         struct kstatfs st;
188         int error;
189         if (sz != sizeof(*buf))
190                 return -EINVAL;
191         error = user_statfs(pathname, &st);
192         if (!error)
193                 error = do_statfs64(&st, buf);
194         return error;
195 }
196 
197 SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
198 {
199         struct kstatfs st;
200         int error = fd_statfs(fd, &st);
201         if (!error)
202                 error = do_statfs_native(&st, buf);
203         return error;
204 }
205 
206 SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
207 {
208         struct kstatfs st;
209         int error;
210 
211         if (sz != sizeof(*buf))
212                 return -EINVAL;
213 
214         error = fd_statfs(fd, &st);
215         if (!error)
216                 error = do_statfs64(&st, buf);
217         return error;
218 }
219 
220 static int vfs_ustat(dev_t dev, struct kstatfs *sbuf)
221 {
222         struct super_block *s = user_get_super(dev);
223         int err;
224         if (!s)
225                 return -EINVAL;
226 
227         err = statfs_by_dentry(s->s_root, sbuf);
228         drop_super(s);
229         return err;
230 }
231 
232 SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
233 {
234         struct ustat tmp;
235         struct kstatfs sbuf;
236         int err = vfs_ustat(new_decode_dev(dev), &sbuf);
237         if (err)
238                 return err;
239 
240         memset(&tmp,0,sizeof(struct ustat));
241         tmp.f_tfree = sbuf.f_bfree;
242         tmp.f_tinode = sbuf.f_ffree;
243 
244         return copy_to_user(ubuf, &tmp, sizeof(struct ustat)) ? -EFAULT : 0;
245 }
246 
247 #ifdef CONFIG_COMPAT
248 static int put_compat_statfs(struct compat_statfs __user *ubuf, struct kstatfs *kbuf)
249 {
250         struct compat_statfs buf;
251         if (sizeof ubuf->f_blocks == 4) {
252                 if ((kbuf->f_blocks | kbuf->f_bfree | kbuf->f_bavail |
253                      kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
254                         return -EOVERFLOW;
255                 /* f_files and f_ffree may be -1; it's okay
256                  * to stuff that into 32 bits */
257                 if (kbuf->f_files != 0xffffffffffffffffULL
258                  && (kbuf->f_files & 0xffffffff00000000ULL))
259                         return -EOVERFLOW;
260                 if (kbuf->f_ffree != 0xffffffffffffffffULL
261                  && (kbuf->f_ffree & 0xffffffff00000000ULL))
262                         return -EOVERFLOW;
263         }
264         memset(&buf, 0, sizeof(struct compat_statfs));
265         buf.f_type = kbuf->f_type;
266         buf.f_bsize = kbuf->f_bsize;
267         buf.f_blocks = kbuf->f_blocks;
268         buf.f_bfree = kbuf->f_bfree;
269         buf.f_bavail = kbuf->f_bavail;
270         buf.f_files = kbuf->f_files;
271         buf.f_ffree = kbuf->f_ffree;
272         buf.f_namelen = kbuf->f_namelen;
273         buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
274         buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
275         buf.f_frsize = kbuf->f_frsize;
276         buf.f_flags = kbuf->f_flags;
277         if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs)))
278                 return -EFAULT;
279         return 0;
280 }
281 
282 /*
283  * The following statfs calls are copies of code from fs/statfs.c and
284  * should be checked against those from time to time
285  */
286 COMPAT_SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct compat_statfs __user *, buf)
287 {
288         struct kstatfs tmp;
289         int error = user_statfs(pathname, &tmp);
290         if (!error)
291                 error = put_compat_statfs(buf, &tmp);
292         return error;
293 }
294 
295 COMPAT_SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct compat_statfs __user *, buf)
296 {
297         struct kstatfs tmp;
298         int error = fd_statfs(fd, &tmp);
299         if (!error)
300                 error = put_compat_statfs(buf, &tmp);
301         return error;
302 }
303 
304 static int put_compat_statfs64(struct compat_statfs64 __user *ubuf, struct kstatfs *kbuf)
305 {
306         struct compat_statfs64 buf;
307         if (sizeof(ubuf->f_bsize) == 4) {
308                 if ((kbuf->f_type | kbuf->f_bsize | kbuf->f_namelen |
309                      kbuf->f_frsize | kbuf->f_flags) & 0xffffffff00000000ULL)
310                         return -EOVERFLOW;
311                 /* f_files and f_ffree may be -1; it's okay
312                  * to stuff that into 32 bits */
313                 if (kbuf->f_files != 0xffffffffffffffffULL
314                  && (kbuf->f_files & 0xffffffff00000000ULL))
315                         return -EOVERFLOW;
316                 if (kbuf->f_ffree != 0xffffffffffffffffULL
317                  && (kbuf->f_ffree & 0xffffffff00000000ULL))
318                         return -EOVERFLOW;
319         }
320         memset(&buf, 0, sizeof(struct compat_statfs64));
321         buf.f_type = kbuf->f_type;
322         buf.f_bsize = kbuf->f_bsize;
323         buf.f_blocks = kbuf->f_blocks;
324         buf.f_bfree = kbuf->f_bfree;
325         buf.f_bavail = kbuf->f_bavail;
326         buf.f_files = kbuf->f_files;
327         buf.f_ffree = kbuf->f_ffree;
328         buf.f_namelen = kbuf->f_namelen;
329         buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
330         buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
331         buf.f_frsize = kbuf->f_frsize;
332         buf.f_flags = kbuf->f_flags;
333         if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs64)))
334                 return -EFAULT;
335         return 0;
336 }
337 
338 COMPAT_SYSCALL_DEFINE3(statfs64, const char __user *, pathname, compat_size_t, sz, struct compat_statfs64 __user *, buf)
339 {
340         struct kstatfs tmp;
341         int error;
342 
343         if (sz != sizeof(*buf))
344                 return -EINVAL;
345 
346         error = user_statfs(pathname, &tmp);
347         if (!error)
348                 error = put_compat_statfs64(buf, &tmp);
349         return error;
350 }
351 
352 COMPAT_SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, compat_size_t, sz, struct compat_statfs64 __user *, buf)
353 {
354         struct kstatfs tmp;
355         int error;
356 
357         if (sz != sizeof(*buf))
358                 return -EINVAL;
359 
360         error = fd_statfs(fd, &tmp);
361         if (!error)
362                 error = put_compat_statfs64(buf, &tmp);
363         return error;
364 }
365 
366 /*
367  * This is a copy of sys_ustat, just dealing with a structure layout.
368  * Given how simple this syscall is that apporach is more maintainable
369  * than the various conversion hacks.
370  */
371 COMPAT_SYSCALL_DEFINE2(ustat, unsigned, dev, struct compat_ustat __user *, u)
372 {
373         struct compat_ustat tmp;
374         struct kstatfs sbuf;
375         int err = vfs_ustat(new_decode_dev(dev), &sbuf);
376         if (err)
377                 return err;
378 
379         memset(&tmp, 0, sizeof(struct compat_ustat));
380         tmp.f_tfree = sbuf.f_bfree;
381         tmp.f_tinode = sbuf.f_ffree;
382         if (copy_to_user(u, &tmp, sizeof(struct compat_ustat)))
383                 return -EFAULT;
384         return 0;
385 }
386 #endif
387 

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