xref: /linux/fs/statfs.c (revision 3fd6c59042dbba50391e30862beac979491145fe)
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 	if (mnt_flags & MNT_NOSYMFOLLOW)
33 		flags |= ST_NOSYMFOLLOW;
34 	return flags;
35 }
36 
flags_by_sb(int s_flags)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 
calculate_f_flags(struct vfsmount * mnt)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 
statfs_by_dentry(struct dentry * dentry,struct kstatfs * buf)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 
vfs_get_fsid(struct dentry * dentry,__kernel_fsid_t * fsid)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 
vfs_statfs(const struct path * path,struct kstatfs * buf)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 
user_statfs(const char __user * pathname,struct kstatfs * st)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 
fd_statfs(int fd,struct kstatfs * st)115 int 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 
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 		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(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 		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(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, false);
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 	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(ubuf, &tmp, sizeof(struct ustat)) ? -EFAULT : 0;
262 }
263 
264 #ifdef CONFIG_COMPAT
put_compat_statfs(struct compat_statfs __user * ubuf,struct kstatfs * kbuf)265 static 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(ubuf, &buf, 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  */
COMPAT_SYSCALL_DEFINE2(statfs,const char __user *,pathname,struct compat_statfs __user *,buf)303 COMPAT_SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct compat_statfs __user *, buf)
304 {
305 	struct kstatfs tmp;
306 	int error = user_statfs(pathname, &tmp);
307 	if (!error)
308 		error = put_compat_statfs(buf, &tmp);
309 	return error;
310 }
311 
COMPAT_SYSCALL_DEFINE2(fstatfs,unsigned int,fd,struct compat_statfs __user *,buf)312 COMPAT_SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct compat_statfs __user *, buf)
313 {
314 	struct kstatfs tmp;
315 	int error = fd_statfs(fd, &tmp);
316 	if (!error)
317 		error = put_compat_statfs(buf, &tmp);
318 	return error;
319 }
320 
put_compat_statfs64(struct compat_statfs64 __user * ubuf,struct kstatfs * kbuf)321 static 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(ubuf, &buf, sizeof(struct compat_statfs64)))
342 		return -EFAULT;
343 	return 0;
344 }
345 
kcompat_sys_statfs64(const char __user * pathname,compat_size_t sz,struct compat_statfs64 __user * buf)346 int 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, &tmp);
355 	if (!error)
356 		error = put_compat_statfs64(buf, &tmp);
357 	return error;
358 }
359 
COMPAT_SYSCALL_DEFINE3(statfs64,const char __user *,pathname,compat_size_t,sz,struct compat_statfs64 __user *,buf)360 COMPAT_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 
kcompat_sys_fstatfs64(unsigned int fd,compat_size_t sz,struct compat_statfs64 __user * buf)365 int 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, &tmp);
374 	if (!error)
375 		error = put_compat_statfs64(buf, &tmp);
376 	return error;
377 }
378 
COMPAT_SYSCALL_DEFINE3(fstatfs64,unsigned int,fd,compat_size_t,sz,struct compat_statfs64 __user *,buf)379 COMPAT_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  */
COMPAT_SYSCALL_DEFINE2(ustat,unsigned,dev,struct compat_ustat __user *,u)389 COMPAT_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(new_decode_dev(dev), &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(u, &tmp, sizeof(struct compat_ustat)))
401 		return -EFAULT;
402 	return 0;
403 }
404 #endif
405