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 memset(&buf, 0, sizeof(buf));
134 if (sizeof buf.f_blocks == 4) {
135 if ((st->f_blocks | st->f_bfree | st->f_bavail |
136 st->f_bsize | st->f_frsize) &
137 0xffffffff00000000ULL)
138 return -EOVERFLOW;
139 /*
140 * f_files and f_ffree may be -1; it's okay to stuff
141 * that into 32 bits
142 */
143 if (st->f_files != -1 &&
144 (st->f_files & 0xffffffff00000000ULL))
145 return -EOVERFLOW;
146 if (st->f_ffree != -1 &&
147 (st->f_ffree & 0xffffffff00000000ULL))
148 return -EOVERFLOW;
149 }
150
151 buf.f_type = st->f_type;
152 buf.f_bsize = st->f_bsize;
153 buf.f_blocks = st->f_blocks;
154 buf.f_bfree = st->f_bfree;
155 buf.f_bavail = st->f_bavail;
156 buf.f_files = st->f_files;
157 buf.f_ffree = st->f_ffree;
158 buf.f_fsid = st->f_fsid;
159 buf.f_namelen = st->f_namelen;
160 buf.f_frsize = st->f_frsize;
161 buf.f_flags = st->f_flags;
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 memset(&buf, 0, sizeof(buf));
175 buf.f_type = st->f_type;
176 buf.f_bsize = st->f_bsize;
177 buf.f_blocks = st->f_blocks;
178 buf.f_bfree = st->f_bfree;
179 buf.f_bavail = st->f_bavail;
180 buf.f_files = st->f_files;
181 buf.f_ffree = st->f_ffree;
182 buf.f_fsid = st->f_fsid;
183 buf.f_namelen = st->f_namelen;
184 buf.f_frsize = st->f_frsize;
185 buf.f_flags = st->f_flags;
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 if (IS_ENABLED(CONFIG_ARCH_32BIT_USTAT_F_TINODE))
259 tmp.f_tinode = min_t(u64, sbuf.f_ffree, UINT_MAX);
260 else
261 tmp.f_tinode = sbuf.f_ffree;
262
263 return copy_to_user(ubuf, &tmp, sizeof(struct ustat)) ? -EFAULT : 0;
264 }
265
266 #ifdef CONFIG_COMPAT
267 static int put_compat_statfs(struct compat_statfs __user *ubuf, struct kstatfs *kbuf)
268 {
269 struct compat_statfs buf;
270 if (sizeof ubuf->f_blocks == 4) {
271 if ((kbuf->f_blocks | kbuf->f_bfree | kbuf->f_bavail |
272 kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
273 return -EOVERFLOW;
274 /* f_files and f_ffree may be -1; it's okay
275 * to stuff that into 32 bits */
276 if (kbuf->f_files != 0xffffffffffffffffULL
277 && (kbuf->f_files & 0xffffffff00000000ULL))
278 return -EOVERFLOW;
279 if (kbuf->f_ffree != 0xffffffffffffffffULL
280 && (kbuf->f_ffree & 0xffffffff00000000ULL))
281 return -EOVERFLOW;
282 }
283 memset(&buf, 0, sizeof(struct compat_statfs));
284 buf.f_type = kbuf->f_type;
285 buf.f_bsize = kbuf->f_bsize;
286 buf.f_blocks = kbuf->f_blocks;
287 buf.f_bfree = kbuf->f_bfree;
288 buf.f_bavail = kbuf->f_bavail;
289 buf.f_files = kbuf->f_files;
290 buf.f_ffree = kbuf->f_ffree;
291 buf.f_namelen = kbuf->f_namelen;
292 buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
293 buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
294 buf.f_frsize = kbuf->f_frsize;
295 buf.f_flags = kbuf->f_flags;
296 if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs)))
297 return -EFAULT;
298 return 0;
299 }
300
301 /*
302 * The following statfs calls are copies of code from fs/statfs.c and
303 * should be checked against those from time to time
304 */
305 COMPAT_SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct compat_statfs __user *, buf)
306 {
307 struct kstatfs tmp;
308 int error = user_statfs(pathname, &tmp);
309 if (!error)
310 error = put_compat_statfs(buf, &tmp);
311 return error;
312 }
313
314 COMPAT_SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct compat_statfs __user *, buf)
315 {
316 struct kstatfs tmp;
317 int error = fd_statfs(fd, &tmp);
318 if (!error)
319 error = put_compat_statfs(buf, &tmp);
320 return error;
321 }
322
323 static int put_compat_statfs64(struct compat_statfs64 __user *ubuf, struct kstatfs *kbuf)
324 {
325 struct compat_statfs64 buf;
326
327 if ((kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
328 return -EOVERFLOW;
329
330 memset(&buf, 0, sizeof(struct compat_statfs64));
331 buf.f_type = kbuf->f_type;
332 buf.f_bsize = kbuf->f_bsize;
333 buf.f_blocks = kbuf->f_blocks;
334 buf.f_bfree = kbuf->f_bfree;
335 buf.f_bavail = kbuf->f_bavail;
336 buf.f_files = kbuf->f_files;
337 buf.f_ffree = kbuf->f_ffree;
338 buf.f_namelen = kbuf->f_namelen;
339 buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
340 buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
341 buf.f_frsize = kbuf->f_frsize;
342 buf.f_flags = kbuf->f_flags;
343 if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs64)))
344 return -EFAULT;
345 return 0;
346 }
347
348 int kcompat_sys_statfs64(const char __user * pathname, compat_size_t sz, struct compat_statfs64 __user * buf)
349 {
350 struct kstatfs tmp;
351 int error;
352
353 if (sz != sizeof(*buf))
354 return -EINVAL;
355
356 error = user_statfs(pathname, &tmp);
357 if (!error)
358 error = put_compat_statfs64(buf, &tmp);
359 return error;
360 }
361
362 COMPAT_SYSCALL_DEFINE3(statfs64, const char __user *, pathname, compat_size_t, sz, struct compat_statfs64 __user *, buf)
363 {
364 return kcompat_sys_statfs64(pathname, sz, buf);
365 }
366
367 int kcompat_sys_fstatfs64(unsigned int fd, compat_size_t sz, struct compat_statfs64 __user * buf)
368 {
369 struct kstatfs tmp;
370 int error;
371
372 if (sz != sizeof(*buf))
373 return -EINVAL;
374
375 error = fd_statfs(fd, &tmp);
376 if (!error)
377 error = put_compat_statfs64(buf, &tmp);
378 return error;
379 }
380
381 COMPAT_SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, compat_size_t, sz, struct compat_statfs64 __user *, buf)
382 {
383 return kcompat_sys_fstatfs64(fd, sz, buf);
384 }
385
386 /*
387 * This is a copy of sys_ustat, just dealing with a structure layout.
388 * Given how simple this syscall is that apporach is more maintainable
389 * than the various conversion hacks.
390 */
391 COMPAT_SYSCALL_DEFINE2(ustat, unsigned, dev, struct compat_ustat __user *, u)
392 {
393 struct compat_ustat tmp;
394 struct kstatfs sbuf;
395 int err = vfs_ustat(new_decode_dev(dev), &sbuf);
396 if (err)
397 return err;
398
399 memset(&tmp, 0, sizeof(struct compat_ustat));
400 tmp.f_tfree = sbuf.f_bfree;
401 tmp.f_tinode = sbuf.f_ffree;
402 if (copy_to_user(u, &tmp, sizeof(struct compat_ustat)))
403 return -EFAULT;
404 return 0;
405 }
406 #endif
407
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