1#include <linux/compiler.h>
2#include <linux/file.h>
3#include <linux/fs.h>
4#include <linux/linkage.h>
5#include <linux/mount.h>
6#include <linux/namei.h>
7#include <linux/sched.h>
8#include <linux/stat.h>
9#include <linux/utime.h>
10#include <linux/syscalls.h>
11#include <asm/uaccess.h>
12#include <asm/unistd.h>
13
14#ifdef __ARCH_WANT_SYS_UTIME
15
16/*
17 * sys_utime() can be implemented in user-level using sys_utimes().
18 * Is this for backwards compatibility?  If so, why not move it
19 * into the appropriate arch directory (for those architectures that
20 * need it).
21 */
22
23/* If times==NULL, set access and modification to current time,
24 * must be owner or have write permission.
25 * Else, update from *times, must be owner or super user.
26 */
27SYSCALL_DEFINE2(utime, char __user *, filename, struct utimbuf __user *, times)
28{
29	struct timespec tv[2];
30
31	if (times) {
32		if (get_user(tv[0].tv_sec, &times->actime) ||
33		    get_user(tv[1].tv_sec, &times->modtime))
34			return -EFAULT;
35		tv[0].tv_nsec = 0;
36		tv[1].tv_nsec = 0;
37	}
38	return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
39}
40
41#endif
42
43static bool nsec_valid(long nsec)
44{
45	if (nsec == UTIME_OMIT || nsec == UTIME_NOW)
46		return true;
47
48	return nsec >= 0 && nsec <= 999999999;
49}
50
51static int utimes_common(struct path *path, struct timespec *times)
52{
53	int error;
54	struct iattr newattrs;
55	struct inode *inode = path->dentry->d_inode;
56	struct inode *delegated_inode = NULL;
57
58	error = mnt_want_write(path->mnt);
59	if (error)
60		goto out;
61
62	if (times && times[0].tv_nsec == UTIME_NOW &&
63		     times[1].tv_nsec == UTIME_NOW)
64		times = NULL;
65
66	newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
67	if (times) {
68		if (times[0].tv_nsec == UTIME_OMIT)
69			newattrs.ia_valid &= ~ATTR_ATIME;
70		else if (times[0].tv_nsec != UTIME_NOW) {
71			newattrs.ia_atime.tv_sec = times[0].tv_sec;
72			newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
73			newattrs.ia_valid |= ATTR_ATIME_SET;
74		}
75
76		if (times[1].tv_nsec == UTIME_OMIT)
77			newattrs.ia_valid &= ~ATTR_MTIME;
78		else if (times[1].tv_nsec != UTIME_NOW) {
79			newattrs.ia_mtime.tv_sec = times[1].tv_sec;
80			newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
81			newattrs.ia_valid |= ATTR_MTIME_SET;
82		}
83		/*
84		 * Tell inode_change_ok(), that this is an explicit time
85		 * update, even if neither ATTR_ATIME_SET nor ATTR_MTIME_SET
86		 * were used.
87		 */
88		newattrs.ia_valid |= ATTR_TIMES_SET;
89	} else {
90		/*
91		 * If times is NULL (or both times are UTIME_NOW),
92		 * then we need to check permissions, because
93		 * inode_change_ok() won't do it.
94		 */
95		error = -EACCES;
96                if (IS_IMMUTABLE(inode))
97			goto mnt_drop_write_and_out;
98
99		if (!inode_owner_or_capable(inode)) {
100			error = inode_permission(inode, MAY_WRITE);
101			if (error)
102				goto mnt_drop_write_and_out;
103		}
104	}
105retry_deleg:
106	mutex_lock(&inode->i_mutex);
107	error = notify_change(path->dentry, &newattrs, &delegated_inode);
108	mutex_unlock(&inode->i_mutex);
109	if (delegated_inode) {
110		error = break_deleg_wait(&delegated_inode);
111		if (!error)
112			goto retry_deleg;
113	}
114
115mnt_drop_write_and_out:
116	mnt_drop_write(path->mnt);
117out:
118	return error;
119}
120
121/*
122 * do_utimes - change times on filename or file descriptor
123 * @dfd: open file descriptor, -1 or AT_FDCWD
124 * @filename: path name or NULL
125 * @times: new times or NULL
126 * @flags: zero or more flags (only AT_SYMLINK_NOFOLLOW for the moment)
127 *
128 * If filename is NULL and dfd refers to an open file, then operate on
129 * the file.  Otherwise look up filename, possibly using dfd as a
130 * starting point.
131 *
132 * If times==NULL, set access and modification to current time,
133 * must be owner or have write permission.
134 * Else, update from *times, must be owner or super user.
135 */
136long do_utimes(int dfd, const char __user *filename, struct timespec *times,
137	       int flags)
138{
139	int error = -EINVAL;
140
141	if (times && (!nsec_valid(times[0].tv_nsec) ||
142		      !nsec_valid(times[1].tv_nsec))) {
143		goto out;
144	}
145
146	if (flags & ~AT_SYMLINK_NOFOLLOW)
147		goto out;
148
149	if (filename == NULL && dfd != AT_FDCWD) {
150		struct fd f;
151
152		if (flags & AT_SYMLINK_NOFOLLOW)
153			goto out;
154
155		f = fdget(dfd);
156		error = -EBADF;
157		if (!f.file)
158			goto out;
159
160		error = utimes_common(&f.file->f_path, times);
161		fdput(f);
162	} else {
163		struct path path;
164		int lookup_flags = 0;
165
166		if (!(flags & AT_SYMLINK_NOFOLLOW))
167			lookup_flags |= LOOKUP_FOLLOW;
168retry:
169		error = user_path_at(dfd, filename, lookup_flags, &path);
170		if (error)
171			goto out;
172
173		error = utimes_common(&path, times);
174		path_put(&path);
175		if (retry_estale(error, lookup_flags)) {
176			lookup_flags |= LOOKUP_REVAL;
177			goto retry;
178		}
179	}
180
181out:
182	return error;
183}
184
185SYSCALL_DEFINE4(utimensat, int, dfd, const char __user *, filename,
186		struct timespec __user *, utimes, int, flags)
187{
188	struct timespec tstimes[2];
189
190	if (utimes) {
191		if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
192			return -EFAULT;
193
194		/* Nothing to do, we must not even check the path.  */
195		if (tstimes[0].tv_nsec == UTIME_OMIT &&
196		    tstimes[1].tv_nsec == UTIME_OMIT)
197			return 0;
198	}
199
200	return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
201}
202
203SYSCALL_DEFINE3(futimesat, int, dfd, const char __user *, filename,
204		struct timeval __user *, utimes)
205{
206	struct timeval times[2];
207	struct timespec tstimes[2];
208
209	if (utimes) {
210		if (copy_from_user(&times, utimes, sizeof(times)))
211			return -EFAULT;
212
213		/* This test is needed to catch all invalid values.  If we
214		   would test only in do_utimes we would miss those invalid
215		   values truncated by the multiplication with 1000.  Note
216		   that we also catch UTIME_{NOW,OMIT} here which are only
217		   valid for utimensat.  */
218		if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
219		    times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
220			return -EINVAL;
221
222		tstimes[0].tv_sec = times[0].tv_sec;
223		tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
224		tstimes[1].tv_sec = times[1].tv_sec;
225		tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
226	}
227
228	return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
229}
230
231SYSCALL_DEFINE2(utimes, char __user *, filename,
232		struct timeval __user *, utimes)
233{
234	return sys_futimesat(AT_FDCWD, filename, utimes);
235}
236