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_statfs(const struct path * path,struct kstatfs * buf)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
user_statfs(const char __user * pathname,struct kstatfs * st)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
fd_statfs(int fd,struct kstatfs * st)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
do_statfs_native(struct kstatfs * st,struct statfs __user * p)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 memset(&buf, 0, sizeof(buf));
118 if (sizeof buf.f_blocks == 4) {
119 if ((st->f_blocks | st->f_bfree | st->f_bavail |
120 st->f_bsize | st->f_frsize) &
121 0xffffffff00000000ULL)
122 return -EOVERFLOW;
123 /*
124 * f_files and f_ffree may be -1; it's okay to stuff
125 * that into 32 bits
126 */
127 if (st->f_files != -1 &&
128 (st->f_files & 0xffffffff00000000ULL))
129 return -EOVERFLOW;
130 if (st->f_ffree != -1 &&
131 (st->f_ffree & 0xffffffff00000000ULL))
132 return -EOVERFLOW;
133 }
134
135 buf.f_type = st->f_type;
136 buf.f_bsize = st->f_bsize;
137 buf.f_blocks = st->f_blocks;
138 buf.f_bfree = st->f_bfree;
139 buf.f_bavail = st->f_bavail;
140 buf.f_files = st->f_files;
141 buf.f_ffree = st->f_ffree;
142 buf.f_fsid = st->f_fsid;
143 buf.f_namelen = st->f_namelen;
144 buf.f_frsize = st->f_frsize;
145 buf.f_flags = st->f_flags;
146 }
147 if (copy_to_user(p, &buf, sizeof(buf)))
148 return -EFAULT;
149 return 0;
150 }
151
do_statfs64(struct kstatfs * st,struct statfs64 __user * p)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 memset(&buf, 0, sizeof(buf));
159 buf.f_type = st->f_type;
160 buf.f_bsize = st->f_bsize;
161 buf.f_blocks = st->f_blocks;
162 buf.f_bfree = st->f_bfree;
163 buf.f_bavail = st->f_bavail;
164 buf.f_files = st->f_files;
165 buf.f_ffree = st->f_ffree;
166 buf.f_fsid = st->f_fsid;
167 buf.f_namelen = st->f_namelen;
168 buf.f_frsize = st->f_frsize;
169 buf.f_flags = st->f_flags;
170 }
171 if (copy_to_user(p, &buf, sizeof(buf)))
172 return -EFAULT;
173 return 0;
174 }
175
SYSCALL_DEFINE2(statfs,const char __user *,pathname,struct statfs __user *,buf)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
SYSCALL_DEFINE3(statfs64,const char __user *,pathname,size_t,sz,struct statfs64 __user *,buf)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
SYSCALL_DEFINE2(fstatfs,unsigned int,fd,struct statfs __user *,buf)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
SYSCALL_DEFINE3(fstatfs64,unsigned int,fd,size_t,sz,struct statfs64 __user *,buf)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
vfs_ustat(dev_t dev,struct kstatfs * sbuf)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
SYSCALL_DEFINE2(ustat,unsigned,dev,struct ustat __user *,ubuf)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
put_compat_statfs(struct compat_statfs __user * ubuf,struct kstatfs * kbuf)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 */
COMPAT_SYSCALL_DEFINE2(statfs,const char __user *,pathname,struct compat_statfs __user *,buf)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
COMPAT_SYSCALL_DEFINE2(fstatfs,unsigned int,fd,struct compat_statfs __user *,buf)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
put_compat_statfs64(struct compat_statfs64 __user * ubuf,struct kstatfs * kbuf)304 static int put_compat_statfs64(struct compat_statfs64 __user *ubuf, struct kstatfs *kbuf)
305 {
306 struct compat_statfs64 buf;
307
308 if ((kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
309 return -EOVERFLOW;
310
311 memset(&buf, 0, sizeof(struct compat_statfs64));
312 buf.f_type = kbuf->f_type;
313 buf.f_bsize = kbuf->f_bsize;
314 buf.f_blocks = kbuf->f_blocks;
315 buf.f_bfree = kbuf->f_bfree;
316 buf.f_bavail = kbuf->f_bavail;
317 buf.f_files = kbuf->f_files;
318 buf.f_ffree = kbuf->f_ffree;
319 buf.f_namelen = kbuf->f_namelen;
320 buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
321 buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
322 buf.f_frsize = kbuf->f_frsize;
323 buf.f_flags = kbuf->f_flags;
324 if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs64)))
325 return -EFAULT;
326 return 0;
327 }
328
kcompat_sys_statfs64(const char __user * pathname,compat_size_t sz,struct compat_statfs64 __user * buf)329 int kcompat_sys_statfs64(const char __user * pathname, compat_size_t sz, struct compat_statfs64 __user * buf)
330 {
331 struct kstatfs tmp;
332 int error;
333
334 if (sz != sizeof(*buf))
335 return -EINVAL;
336
337 error = user_statfs(pathname, &tmp);
338 if (!error)
339 error = put_compat_statfs64(buf, &tmp);
340 return error;
341 }
342
COMPAT_SYSCALL_DEFINE3(statfs64,const char __user *,pathname,compat_size_t,sz,struct compat_statfs64 __user *,buf)343 COMPAT_SYSCALL_DEFINE3(statfs64, const char __user *, pathname, compat_size_t, sz, struct compat_statfs64 __user *, buf)
344 {
345 return kcompat_sys_statfs64(pathname, sz, buf);
346 }
347
kcompat_sys_fstatfs64(unsigned int fd,compat_size_t sz,struct compat_statfs64 __user * buf)348 int kcompat_sys_fstatfs64(unsigned int fd, 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 = fd_statfs(fd, &tmp);
357 if (!error)
358 error = put_compat_statfs64(buf, &tmp);
359 return error;
360 }
361
COMPAT_SYSCALL_DEFINE3(fstatfs64,unsigned int,fd,compat_size_t,sz,struct compat_statfs64 __user *,buf)362 COMPAT_SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, compat_size_t, sz, struct compat_statfs64 __user *, buf)
363 {
364 return kcompat_sys_fstatfs64(fd, sz, buf);
365 }
366
367 /*
368 * This is a copy of sys_ustat, just dealing with a structure layout.
369 * Given how simple this syscall is that apporach is more maintainable
370 * than the various conversion hacks.
371 */
COMPAT_SYSCALL_DEFINE2(ustat,unsigned,dev,struct compat_ustat __user *,u)372 COMPAT_SYSCALL_DEFINE2(ustat, unsigned, dev, struct compat_ustat __user *, u)
373 {
374 struct compat_ustat tmp;
375 struct kstatfs sbuf;
376 int err = vfs_ustat(new_decode_dev(dev), &sbuf);
377 if (err)
378 return err;
379
380 memset(&tmp, 0, sizeof(struct compat_ustat));
381 tmp.f_tfree = sbuf.f_bfree;
382 tmp.f_tinode = sbuf.f_ffree;
383 if (copy_to_user(u, &tmp, sizeof(struct compat_ustat)))
384 return -EFAULT;
385 return 0;
386 }
387 #endif
388