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
14static 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
37static 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
49static int calculate_f_flags(struct vfsmount *mnt)
50{
51 return ST_VALID | flags_by_mnt(mnt_flags: mnt->mnt_flags) |
52 flags_by_sb(s_flags: mnt->mnt_sb->s_flags);
53}
54
55static 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
72int 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, buf: &st);
78 if (error)
79 return error;
80
81 *fsid = st.f_fsid;
82 return 0;
83}
84EXPORT_SYMBOL(vfs_get_fsid);
85
86int vfs_statfs(const struct path *path, struct kstatfs *buf)
87{
88 int error;
89
90 error = statfs_by_dentry(dentry: path->dentry, buf);
91 if (!error)
92 buf->f_flags = calculate_f_flags(mnt: path->mnt);
93 return error;
94}
95EXPORT_SYMBOL(vfs_statfs);
96
97int 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;
102retry:
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, flags: lookup_flags)) {
108 lookup_flags |= LOOKUP_REVAL;
109 goto retry;
110 }
111 }
112 return error;
113}
114
115int fd_statfs(int fd, struct kstatfs *st)
116{
117 CLASS(fd_raw, f)(fd);
118
119 if (fd_empty(f))
120 return -EBADF;
121 return vfs_statfs(&fd_file(f)->f_path, st);
122}
123
124static int do_statfs_native(struct kstatfs *st, struct statfs __user *p)
125{
126 struct statfs buf;
127
128 if (sizeof(buf) == sizeof(*st))
129 memcpy(&buf, st, sizeof(*st));
130 else {
131 memset(&buf, 0, sizeof(buf));
132 if (sizeof buf.f_blocks == 4) {
133 if ((st->f_blocks | st->f_bfree | st->f_bavail |
134 st->f_bsize | st->f_frsize) &
135 0xffffffff00000000ULL)
136 return -EOVERFLOW;
137 /*
138 * f_files and f_ffree may be -1; it's okay to stuff
139 * that into 32 bits
140 */
141 if (st->f_files != -1 &&
142 (st->f_files & 0xffffffff00000000ULL))
143 return -EOVERFLOW;
144 if (st->f_ffree != -1 &&
145 (st->f_ffree & 0xffffffff00000000ULL))
146 return -EOVERFLOW;
147 }
148
149 buf.f_type = st->f_type;
150 buf.f_bsize = st->f_bsize;
151 buf.f_blocks = st->f_blocks;
152 buf.f_bfree = st->f_bfree;
153 buf.f_bavail = st->f_bavail;
154 buf.f_files = st->f_files;
155 buf.f_ffree = st->f_ffree;
156 buf.f_fsid = st->f_fsid;
157 buf.f_namelen = st->f_namelen;
158 buf.f_frsize = st->f_frsize;
159 buf.f_flags = st->f_flags;
160 }
161 if (copy_to_user(to: p, from: &buf, n: sizeof(buf)))
162 return -EFAULT;
163 return 0;
164}
165
166static int do_statfs64(struct kstatfs *st, struct statfs64 __user *p)
167{
168 struct statfs64 buf;
169 if (sizeof(buf) == sizeof(*st))
170 memcpy(&buf, st, sizeof(*st));
171 else {
172 memset(&buf, 0, sizeof(buf));
173 buf.f_type = st->f_type;
174 buf.f_bsize = st->f_bsize;
175 buf.f_blocks = st->f_blocks;
176 buf.f_bfree = st->f_bfree;
177 buf.f_bavail = st->f_bavail;
178 buf.f_files = st->f_files;
179 buf.f_ffree = st->f_ffree;
180 buf.f_fsid = st->f_fsid;
181 buf.f_namelen = st->f_namelen;
182 buf.f_frsize = st->f_frsize;
183 buf.f_flags = st->f_flags;
184 }
185 if (copy_to_user(to: p, from: &buf, n: sizeof(buf)))
186 return -EFAULT;
187 return 0;
188}
189
190SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
191{
192 struct kstatfs st;
193 int error = user_statfs(pathname, st: &st);
194 if (!error)
195 error = do_statfs_native(st: &st, p: buf);
196 return error;
197}
198
199SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
200{
201 struct kstatfs st;
202 int error;
203 if (sz != sizeof(*buf))
204 return -EINVAL;
205 error = user_statfs(pathname, st: &st);
206 if (!error)
207 error = do_statfs64(st: &st, p: buf);
208 return error;
209}
210
211SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
212{
213 struct kstatfs st;
214 int error = fd_statfs(fd, st: &st);
215 if (!error)
216 error = do_statfs_native(st: &st, p: buf);
217 return error;
218}
219
220SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
221{
222 struct kstatfs st;
223 int error;
224
225 if (sz != sizeof(*buf))
226 return -EINVAL;
227
228 error = fd_statfs(fd, st: &st);
229 if (!error)
230 error = do_statfs64(st: &st, p: buf);
231 return error;
232}
233
234static int vfs_ustat(dev_t dev, struct kstatfs *sbuf)
235{
236 struct super_block *s = user_get_super(dev, excl: false);
237 int err;
238 if (!s)
239 return -EINVAL;
240
241 err = statfs_by_dentry(dentry: s->s_root, buf: sbuf);
242 drop_super(sb: s);
243 return err;
244}
245
246SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
247{
248 struct ustat tmp;
249 struct kstatfs sbuf;
250 int err = vfs_ustat(dev: new_decode_dev(dev), sbuf: &sbuf);
251 if (err)
252 return err;
253
254 memset(&tmp,0,sizeof(struct ustat));
255 tmp.f_tfree = sbuf.f_bfree;
256 if (IS_ENABLED(CONFIG_ARCH_32BIT_USTAT_F_TINODE))
257 tmp.f_tinode = min_t(u64, sbuf.f_ffree, UINT_MAX);
258 else
259 tmp.f_tinode = sbuf.f_ffree;
260
261 return copy_to_user(to: ubuf, from: &tmp, n: sizeof(struct ustat)) ? -EFAULT : 0;
262}
263
264#ifdef CONFIG_COMPAT
265static int put_compat_statfs(struct compat_statfs __user *ubuf, struct kstatfs *kbuf)
266{
267 struct compat_statfs buf;
268 if (sizeof ubuf->f_blocks == 4) {
269 if ((kbuf->f_blocks | kbuf->f_bfree | kbuf->f_bavail |
270 kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
271 return -EOVERFLOW;
272 /* f_files and f_ffree may be -1; it's okay
273 * to stuff that into 32 bits */
274 if (kbuf->f_files != 0xffffffffffffffffULL
275 && (kbuf->f_files & 0xffffffff00000000ULL))
276 return -EOVERFLOW;
277 if (kbuf->f_ffree != 0xffffffffffffffffULL
278 && (kbuf->f_ffree & 0xffffffff00000000ULL))
279 return -EOVERFLOW;
280 }
281 memset(&buf, 0, sizeof(struct compat_statfs));
282 buf.f_type = kbuf->f_type;
283 buf.f_bsize = kbuf->f_bsize;
284 buf.f_blocks = kbuf->f_blocks;
285 buf.f_bfree = kbuf->f_bfree;
286 buf.f_bavail = kbuf->f_bavail;
287 buf.f_files = kbuf->f_files;
288 buf.f_ffree = kbuf->f_ffree;
289 buf.f_namelen = kbuf->f_namelen;
290 buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
291 buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
292 buf.f_frsize = kbuf->f_frsize;
293 buf.f_flags = kbuf->f_flags;
294 if (copy_to_user(to: ubuf, from: &buf, n: sizeof(struct compat_statfs)))
295 return -EFAULT;
296 return 0;
297}
298
299/*
300 * The following statfs calls are copies of code from fs/statfs.c and
301 * should be checked against those from time to time
302 */
303COMPAT_SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct compat_statfs __user *, buf)
304{
305 struct kstatfs tmp;
306 int error = user_statfs(pathname, st: &tmp);
307 if (!error)
308 error = put_compat_statfs(ubuf: buf, kbuf: &tmp);
309 return error;
310}
311
312COMPAT_SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct compat_statfs __user *, buf)
313{
314 struct kstatfs tmp;
315 int error = fd_statfs(fd, st: &tmp);
316 if (!error)
317 error = put_compat_statfs(ubuf: buf, kbuf: &tmp);
318 return error;
319}
320
321static int put_compat_statfs64(struct compat_statfs64 __user *ubuf, struct kstatfs *kbuf)
322{
323 struct compat_statfs64 buf;
324
325 if ((kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
326 return -EOVERFLOW;
327
328 memset(&buf, 0, sizeof(struct compat_statfs64));
329 buf.f_type = kbuf->f_type;
330 buf.f_bsize = kbuf->f_bsize;
331 buf.f_blocks = kbuf->f_blocks;
332 buf.f_bfree = kbuf->f_bfree;
333 buf.f_bavail = kbuf->f_bavail;
334 buf.f_files = kbuf->f_files;
335 buf.f_ffree = kbuf->f_ffree;
336 buf.f_namelen = kbuf->f_namelen;
337 buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
338 buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
339 buf.f_frsize = kbuf->f_frsize;
340 buf.f_flags = kbuf->f_flags;
341 if (copy_to_user(to: ubuf, from: &buf, n: sizeof(struct compat_statfs64)))
342 return -EFAULT;
343 return 0;
344}
345
346int kcompat_sys_statfs64(const char __user * pathname, compat_size_t sz, struct compat_statfs64 __user * buf)
347{
348 struct kstatfs tmp;
349 int error;
350
351 if (sz != sizeof(*buf))
352 return -EINVAL;
353
354 error = user_statfs(pathname, st: &tmp);
355 if (!error)
356 error = put_compat_statfs64(ubuf: buf, kbuf: &tmp);
357 return error;
358}
359
360COMPAT_SYSCALL_DEFINE3(statfs64, const char __user *, pathname, compat_size_t, sz, struct compat_statfs64 __user *, buf)
361{
362 return kcompat_sys_statfs64(pathname, sz, buf);
363}
364
365int kcompat_sys_fstatfs64(unsigned int fd, compat_size_t sz, struct compat_statfs64 __user * buf)
366{
367 struct kstatfs tmp;
368 int error;
369
370 if (sz != sizeof(*buf))
371 return -EINVAL;
372
373 error = fd_statfs(fd, st: &tmp);
374 if (!error)
375 error = put_compat_statfs64(ubuf: buf, kbuf: &tmp);
376 return error;
377}
378
379COMPAT_SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, compat_size_t, sz, struct compat_statfs64 __user *, buf)
380{
381 return kcompat_sys_fstatfs64(fd, sz, buf);
382}
383
384/*
385 * This is a copy of sys_ustat, just dealing with a structure layout.
386 * Given how simple this syscall is that apporach is more maintainable
387 * than the various conversion hacks.
388 */
389COMPAT_SYSCALL_DEFINE2(ustat, unsigned, dev, struct compat_ustat __user *, u)
390{
391 struct compat_ustat tmp;
392 struct kstatfs sbuf;
393 int err = vfs_ustat(dev: new_decode_dev(dev), sbuf: &sbuf);
394 if (err)
395 return err;
396
397 memset(&tmp, 0, sizeof(struct compat_ustat));
398 tmp.f_tfree = sbuf.f_bfree;
399 tmp.f_tinode = sbuf.f_ffree;
400 if (copy_to_user(to: u, from: &tmp, n: sizeof(struct compat_ustat)))
401 return -EFAULT;
402 return 0;
403}
404#endif
405

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source code of linux/fs/statfs.c