xref: /openbmc/linux/fs/statfs.c (revision b9ddb2500e7e544410f38476ab928fc2fe01e381)
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  	if (mnt_flags & MNT_NOSYMFOLLOW)
33  		flags |= ST_NOSYMFOLLOW;
34  	return flags;
35  }
36  
37  static int flags_by_sb(int s_flags)
38  {
39  	int flags = 0;
40  	if (s_flags & SB_SYNCHRONOUS)
41  		flags |= ST_SYNCHRONOUS;
42  	if (s_flags & SB_MANDLOCK)
43  		flags |= ST_MANDLOCK;
44  	if (s_flags & SB_RDONLY)
45  		flags |= ST_RDONLY;
46  	return flags;
47  }
48  
49  static int calculate_f_flags(struct vfsmount *mnt)
50  {
51  	return ST_VALID | flags_by_mnt(mnt->mnt_flags) |
52  		flags_by_sb(mnt->mnt_sb->s_flags);
53  }
54  
55  static int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf)
56  {
57  	int retval;
58  
59  	if (!dentry->d_sb->s_op->statfs)
60  		return -ENOSYS;
61  
62  	memset(buf, 0, sizeof(*buf));
63  	retval = security_sb_statfs(dentry);
64  	if (retval)
65  		return retval;
66  	retval = dentry->d_sb->s_op->statfs(dentry, buf);
67  	if (retval == 0 && buf->f_frsize == 0)
68  		buf->f_frsize = buf->f_bsize;
69  	return retval;
70  }
71  
72  int vfs_get_fsid(struct dentry *dentry, __kernel_fsid_t *fsid)
73  {
74  	struct kstatfs st;
75  	int error;
76  
77  	error = statfs_by_dentry(dentry, &st);
78  	if (error)
79  		return error;
80  
81  	*fsid = st.f_fsid;
82  	return 0;
83  }
84  EXPORT_SYMBOL(vfs_get_fsid);
85  
86  int vfs_statfs(const struct path *path, struct kstatfs *buf)
87  {
88  	int error;
89  
90  	error = statfs_by_dentry(path->dentry, buf);
91  	if (!error)
92  		buf->f_flags = calculate_f_flags(path->mnt);
93  	return error;
94  }
95  EXPORT_SYMBOL(vfs_statfs);
96  
97  int user_statfs(const char __user *pathname, struct kstatfs *st)
98  {
99  	struct path path;
100  	int error;
101  	unsigned int lookup_flags = LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT;
102  retry:
103  	error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
104  	if (!error) {
105  		error = vfs_statfs(&path, st);
106  		path_put(&path);
107  		if (retry_estale(error, lookup_flags)) {
108  			lookup_flags |= LOOKUP_REVAL;
109  			goto retry;
110  		}
111  	}
112  	return error;
113  }
114  
115  int fd_statfs(int fd, struct kstatfs *st)
116  {
117  	struct fd f = fdget_raw(fd);
118  	int error = -EBADF;
119  	if (f.file) {
120  		error = vfs_statfs(&f.file->f_path, st);
121  		fdput(f);
122  	}
123  	return error;
124  }
125  
126  static int do_statfs_native(struct kstatfs *st, struct statfs __user *p)
127  {
128  	struct statfs buf;
129  
130  	if (sizeof(buf) == sizeof(*st))
131  		memcpy(&buf, st, sizeof(*st));
132  	else {
133  		if (sizeof buf.f_blocks == 4) {
134  			if ((st->f_blocks | st->f_bfree | st->f_bavail |
135  			     st->f_bsize | st->f_frsize) &
136  			    0xffffffff00000000ULL)
137  				return -EOVERFLOW;
138  			/*
139  			 * f_files and f_ffree may be -1; it's okay to stuff
140  			 * that into 32 bits
141  			 */
142  			if (st->f_files != -1 &&
143  			    (st->f_files & 0xffffffff00000000ULL))
144  				return -EOVERFLOW;
145  			if (st->f_ffree != -1 &&
146  			    (st->f_ffree & 0xffffffff00000000ULL))
147  				return -EOVERFLOW;
148  		}
149  
150  		buf.f_type = st->f_type;
151  		buf.f_bsize = st->f_bsize;
152  		buf.f_blocks = st->f_blocks;
153  		buf.f_bfree = st->f_bfree;
154  		buf.f_bavail = st->f_bavail;
155  		buf.f_files = st->f_files;
156  		buf.f_ffree = st->f_ffree;
157  		buf.f_fsid = st->f_fsid;
158  		buf.f_namelen = st->f_namelen;
159  		buf.f_frsize = st->f_frsize;
160  		buf.f_flags = st->f_flags;
161  		memset(buf.f_spare, 0, sizeof(buf.f_spare));
162  	}
163  	if (copy_to_user(p, &buf, sizeof(buf)))
164  		return -EFAULT;
165  	return 0;
166  }
167  
168  static int do_statfs64(struct kstatfs *st, struct statfs64 __user *p)
169  {
170  	struct statfs64 buf;
171  	if (sizeof(buf) == sizeof(*st))
172  		memcpy(&buf, st, sizeof(*st));
173  	else {
174  		buf.f_type = st->f_type;
175  		buf.f_bsize = st->f_bsize;
176  		buf.f_blocks = st->f_blocks;
177  		buf.f_bfree = st->f_bfree;
178  		buf.f_bavail = st->f_bavail;
179  		buf.f_files = st->f_files;
180  		buf.f_ffree = st->f_ffree;
181  		buf.f_fsid = st->f_fsid;
182  		buf.f_namelen = st->f_namelen;
183  		buf.f_frsize = st->f_frsize;
184  		buf.f_flags = st->f_flags;
185  		memset(buf.f_spare, 0, sizeof(buf.f_spare));
186  	}
187  	if (copy_to_user(p, &buf, sizeof(buf)))
188  		return -EFAULT;
189  	return 0;
190  }
191  
192  SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
193  {
194  	struct kstatfs st;
195  	int error = user_statfs(pathname, &st);
196  	if (!error)
197  		error = do_statfs_native(&st, buf);
198  	return error;
199  }
200  
201  SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
202  {
203  	struct kstatfs st;
204  	int error;
205  	if (sz != sizeof(*buf))
206  		return -EINVAL;
207  	error = user_statfs(pathname, &st);
208  	if (!error)
209  		error = do_statfs64(&st, buf);
210  	return error;
211  }
212  
213  SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
214  {
215  	struct kstatfs st;
216  	int error = fd_statfs(fd, &st);
217  	if (!error)
218  		error = do_statfs_native(&st, buf);
219  	return error;
220  }
221  
222  SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
223  {
224  	struct kstatfs st;
225  	int error;
226  
227  	if (sz != sizeof(*buf))
228  		return -EINVAL;
229  
230  	error = fd_statfs(fd, &st);
231  	if (!error)
232  		error = do_statfs64(&st, buf);
233  	return error;
234  }
235  
236  static int vfs_ustat(dev_t dev, struct kstatfs *sbuf)
237  {
238  	struct super_block *s = user_get_super(dev, false);
239  	int err;
240  	if (!s)
241  		return -EINVAL;
242  
243  	err = statfs_by_dentry(s->s_root, sbuf);
244  	drop_super(s);
245  	return err;
246  }
247  
248  SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
249  {
250  	struct ustat tmp;
251  	struct kstatfs sbuf;
252  	int err = vfs_ustat(new_decode_dev(dev), &sbuf);
253  	if (err)
254  		return err;
255  
256  	memset(&tmp,0,sizeof(struct ustat));
257  	tmp.f_tfree = sbuf.f_bfree;
258  	tmp.f_tinode = sbuf.f_ffree;
259  
260  	return copy_to_user(ubuf, &tmp, sizeof(struct ustat)) ? -EFAULT : 0;
261  }
262  
263  #ifdef CONFIG_COMPAT
264  static int put_compat_statfs(struct compat_statfs __user *ubuf, struct kstatfs *kbuf)
265  {
266  	struct compat_statfs buf;
267  	if (sizeof ubuf->f_blocks == 4) {
268  		if ((kbuf->f_blocks | kbuf->f_bfree | kbuf->f_bavail |
269  		     kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
270  			return -EOVERFLOW;
271  		/* f_files and f_ffree may be -1; it's okay
272  		 * to stuff that into 32 bits */
273  		if (kbuf->f_files != 0xffffffffffffffffULL
274  		 && (kbuf->f_files & 0xffffffff00000000ULL))
275  			return -EOVERFLOW;
276  		if (kbuf->f_ffree != 0xffffffffffffffffULL
277  		 && (kbuf->f_ffree & 0xffffffff00000000ULL))
278  			return -EOVERFLOW;
279  	}
280  	memset(&buf, 0, sizeof(struct compat_statfs));
281  	buf.f_type = kbuf->f_type;
282  	buf.f_bsize = kbuf->f_bsize;
283  	buf.f_blocks = kbuf->f_blocks;
284  	buf.f_bfree = kbuf->f_bfree;
285  	buf.f_bavail = kbuf->f_bavail;
286  	buf.f_files = kbuf->f_files;
287  	buf.f_ffree = kbuf->f_ffree;
288  	buf.f_namelen = kbuf->f_namelen;
289  	buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
290  	buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
291  	buf.f_frsize = kbuf->f_frsize;
292  	buf.f_flags = kbuf->f_flags;
293  	if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs)))
294  		return -EFAULT;
295  	return 0;
296  }
297  
298  /*
299   * The following statfs calls are copies of code from fs/statfs.c and
300   * should be checked against those from time to time
301   */
302  COMPAT_SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct compat_statfs __user *, buf)
303  {
304  	struct kstatfs tmp;
305  	int error = user_statfs(pathname, &tmp);
306  	if (!error)
307  		error = put_compat_statfs(buf, &tmp);
308  	return error;
309  }
310  
311  COMPAT_SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct compat_statfs __user *, buf)
312  {
313  	struct kstatfs tmp;
314  	int error = fd_statfs(fd, &tmp);
315  	if (!error)
316  		error = put_compat_statfs(buf, &tmp);
317  	return error;
318  }
319  
320  static int put_compat_statfs64(struct compat_statfs64 __user *ubuf, struct kstatfs *kbuf)
321  {
322  	struct compat_statfs64 buf;
323  
324  	if ((kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
325  		return -EOVERFLOW;
326  
327  	memset(&buf, 0, sizeof(struct compat_statfs64));
328  	buf.f_type = kbuf->f_type;
329  	buf.f_bsize = kbuf->f_bsize;
330  	buf.f_blocks = kbuf->f_blocks;
331  	buf.f_bfree = kbuf->f_bfree;
332  	buf.f_bavail = kbuf->f_bavail;
333  	buf.f_files = kbuf->f_files;
334  	buf.f_ffree = kbuf->f_ffree;
335  	buf.f_namelen = kbuf->f_namelen;
336  	buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
337  	buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
338  	buf.f_frsize = kbuf->f_frsize;
339  	buf.f_flags = kbuf->f_flags;
340  	if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs64)))
341  		return -EFAULT;
342  	return 0;
343  }
344  
345  int kcompat_sys_statfs64(const char __user * pathname, compat_size_t sz, struct compat_statfs64 __user * buf)
346  {
347  	struct kstatfs tmp;
348  	int error;
349  
350  	if (sz != sizeof(*buf))
351  		return -EINVAL;
352  
353  	error = user_statfs(pathname, &tmp);
354  	if (!error)
355  		error = put_compat_statfs64(buf, &tmp);
356  	return error;
357  }
358  
359  COMPAT_SYSCALL_DEFINE3(statfs64, const char __user *, pathname, compat_size_t, sz, struct compat_statfs64 __user *, buf)
360  {
361  	return kcompat_sys_statfs64(pathname, sz, buf);
362  }
363  
364  int kcompat_sys_fstatfs64(unsigned int fd, compat_size_t sz, struct compat_statfs64 __user * buf)
365  {
366  	struct kstatfs tmp;
367  	int error;
368  
369  	if (sz != sizeof(*buf))
370  		return -EINVAL;
371  
372  	error = fd_statfs(fd, &tmp);
373  	if (!error)
374  		error = put_compat_statfs64(buf, &tmp);
375  	return error;
376  }
377  
378  COMPAT_SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, compat_size_t, sz, struct compat_statfs64 __user *, buf)
379  {
380  	return kcompat_sys_fstatfs64(fd, sz, buf);
381  }
382  
383  /*
384   * This is a copy of sys_ustat, just dealing with a structure layout.
385   * Given how simple this syscall is that apporach is more maintainable
386   * than the various conversion hacks.
387   */
388  COMPAT_SYSCALL_DEFINE2(ustat, unsigned, dev, struct compat_ustat __user *, u)
389  {
390  	struct compat_ustat tmp;
391  	struct kstatfs sbuf;
392  	int err = vfs_ustat(new_decode_dev(dev), &sbuf);
393  	if (err)
394  		return err;
395  
396  	memset(&tmp, 0, sizeof(struct compat_ustat));
397  	tmp.f_tfree = sbuf.f_bfree;
398  	tmp.f_tinode = sbuf.f_ffree;
399  	if (copy_to_user(u, &tmp, sizeof(struct compat_ustat)))
400  		return -EFAULT;
401  	return 0;
402  }
403  #endif
404