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