summaryrefslogtreecommitdiffstats
path: root/fs/utimes.c
blob: dc28b7826259f92557f358341b1a7b275e90c666 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
#include <linux/compiler.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/linkage.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/sched.h>
#include <linux/stat.h>
#include <linux/utime.h>
#include <linux/syscalls.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>

#ifdef __ARCH_WANT_SYS_UTIME

/*
 * sys_utime() can be implemented in user-level using sys_utimes().
 * Is this for backwards compatibility?  If so, why not move it
 * into the appropriate arch directory (for those architectures that
 * need it).
 */

/* If times==NULL, set access and modification to current time,
 * must be owner or have write permission.
 * Else, update from *times, must be owner or super user.
 */
asmlinkage long sys_utime(char __user *filename, struct utimbuf __user *times)
{
	struct timespec tv[2];

	if (times) {
		if (get_user(tv[0].tv_sec, &times->actime) ||
		    get_user(tv[1].tv_sec, &times->modtime))
			return -EFAULT;
		tv[0].tv_nsec = 0;
		tv[1].tv_nsec = 0;
	}
	return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
}

#endif

static bool nsec_valid(long nsec)
{
	if (nsec == UTIME_OMIT || nsec == UTIME_NOW)
		return true;

	return nsec >= 0 && nsec <= 999999999;
}

static int utimes_common(struct path *path, struct timespec *times)
{
	int error;
	struct iattr newattrs;
	struct inode *inode = path->dentry->d_inode;

	error = mnt_want_write(path->mnt);
	if (error)
		goto out;

	if (times && times[0].tv_nsec == UTIME_NOW &&
		     times[1].tv_nsec == UTIME_NOW)
		times = NULL;

	newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
	if (times) {
		if (times[0].tv_nsec == UTIME_OMIT)
			newattrs.ia_valid &= ~ATTR_ATIME;
		else if (times[0].tv_nsec != UTIME_NOW) {
			newattrs.ia_atime.tv_sec = times[0].tv_sec;
			newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
			newattrs.ia_valid |= ATTR_ATIME_SET;
		}

		if (times[1].tv_nsec == UTIME_OMIT)
			newattrs.ia_valid &= ~ATTR_MTIME;
		else if (times[1].tv_nsec != UTIME_NOW) {
			newattrs.ia_mtime.tv_sec = times[1].tv_sec;
			newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
			newattrs.ia_valid |= ATTR_MTIME_SET;
		}
		/*
		 * Tell inode_change_ok(), that this is an explicit time
		 * update, even if neither ATTR_ATIME_SET nor ATTR_MTIME_SET
		 * were used.
		 */
		newattrs.ia_valid |= ATTR_TIMES_SET;
	} else {
		/*
		 * If times is NULL (or both times are UTIME_NOW),
		 * then we need to check permissions, because
		 * inode_change_ok() won't do it.
		 */
		error = -EACCES;
                if (IS_IMMUTABLE(inode))
			goto mnt_drop_write_and_out;

		if (!is_owner_or_cap(inode)) {
			error = inode_permission(inode, MAY_WRITE);
			if (error)
				goto mnt_drop_write_and_out;
		}
	}
	mutex_lock(&inode->i_mutex);
	error = notify_change(path->dentry, &newattrs);
	mutex_unlock(&inode->i_mutex);

mnt_drop_write_and_out:
	mnt_drop_write(path->mnt);
out:
	return error;
}

/*
 * do_utimes - change times on filename or file descriptor
 * @dfd: open file descriptor, -1 or AT_FDCWD
 * @filename: path name or NULL
 * @times: new times or NULL
 * @flags: zero or more flags (only AT_SYMLINK_NOFOLLOW for the moment)
 *
 * If filename is NULL and dfd refers to an open file, then operate on
 * the file.  Otherwise look up filename, possibly using dfd as a
 * starting point.
 *
 * If times==NULL, set access and modification to current time,
 * must be owner or have write permission.
 * Else, update from *times, must be owner or super user.
 */
long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags)
{
	int error = -EINVAL;

	if (times && (!nsec_valid(times[0].tv_nsec) ||
		      !nsec_valid(times[1].tv_nsec))) {
		goto out;
	}

	if (flags & ~AT_SYMLINK_NOFOLLOW)
		goto out;

	if (filename == NULL && dfd != AT_FDCWD) {
		struct file *file;

		if (flags & AT_SYMLINK_NOFOLLOW)
			goto out;

		file = fget(dfd);
		error = -EBADF;
		if (!file)
			goto out;

		error = utimes_common(&file->f_path, times);
		fput(file);
	} else {
		struct nameidata nd;
		int lookup_flags = 0;

		if (!(flags & AT_SYMLINK_NOFOLLOW))
			lookup_flags |= LOOKUP_FOLLOW;

		error = __user_walk_fd(dfd, filename, lookup_flags, &nd);
		if (error)
			goto out;

		error = utimes_common(&nd.path, times);
		path_put(&nd.path);
	}

out:
	return error;
}

asmlinkage long sys_utimensat(int dfd, char __user *filename, struct timespec __user *utimes, int flags)
{
	struct timespec tstimes[2];

	if (utimes) {
		if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
			return -EFAULT;

		/* Nothing to do, we must not even check the path.  */
		if (tstimes[0].tv_nsec == UTIME_OMIT &&
		    tstimes[1].tv_nsec == UTIME_OMIT)
			return 0;
	}

	return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
}

asmlinkage long sys_futimesat(int dfd, char __user *filename, struct timeval __user *utimes)
{
	struct timeval times[2];
	struct timespec tstimes[2];

	if (utimes) {
		if (copy_from_user(&times, utimes, sizeof(times)))
			return -EFAULT;

		/* This test is needed to catch all invalid values.  If we
		   would test only in do_utimes we would miss those invalid
		   values truncated by the multiplication with 1000.  Note
		   that we also catch UTIME_{NOW,OMIT} here which are only
		   valid for utimensat.  */
		if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
		    times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
			return -EINVAL;

		tstimes[0].tv_sec = times[0].tv_sec;
		tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
		tstimes[1].tv_sec = times[1].tv_sec;
		tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
	}

	return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
}

asmlinkage long sys_utimes(char __user *filename, struct timeval __user *utimes)
{
	return sys_futimesat(AT_FDCWD, filename, utimes);
}
OpenPOWER on IntegriCloud