1#include <linux/compiler.h>
2#include <linux/file.h>
3#include <linux/fs.h>
4#include <linux/linkage.h>
5#include <linux/namei.h>
6#include <linux/sched.h>
7#include <linux/stat.h>
8#include <linux/utime.h>
9#include <asm/uaccess.h>
10#include <asm/unistd.h>
11
12#ifdef __ARCH_WANT_SYS_UTIME
13
14/*
15 * sys_utime() can be implemented in user-level using sys_utimes().
16 * Is this for backwards compatibility?  If so, why not move it
17 * into the appropriate arch directory (for those architectures that
18 * need it).
19 */
20
21/* If times==NULL, set access and modification to current time,
22 * must be owner or have write permission.
23 * Else, update from *times, must be owner or super user.
24 */
25asmlinkage long sys_utime(char __user *filename, struct utimbuf __user *times)
26{
27	struct timespec tv[2];
28
29	if (times) {
30		if (get_user(tv[0].tv_sec, &times->actime) ||
31		    get_user(tv[1].tv_sec, &times->modtime))
32			return -EFAULT;
33		tv[0].tv_nsec = 0;
34		tv[1].tv_nsec = 0;
35	}
36	return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
37}
38
39#endif
40
41/* If times==NULL, set access and modification to current time,
42 * must be owner or have write permission.
43 * Else, update from *times, must be owner or super user.
44 */
45long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags)
46{
47	int error;
48	struct nameidata nd;
49	struct dentry *dentry;
50	struct inode *inode;
51	struct iattr newattrs;
52	struct file *f = NULL;
53
54	error = -EINVAL;
55	if (flags & ~AT_SYMLINK_NOFOLLOW)
56		goto out;
57
58	if (filename == NULL && dfd != AT_FDCWD) {
59		error = -EINVAL;
60		if (flags & AT_SYMLINK_NOFOLLOW)
61			goto out;
62
63		error = -EBADF;
64		f = fget(dfd);
65		if (!f)
66			goto out;
67		dentry = f->f_path.dentry;
68	} else {
69		error = __user_walk_fd(dfd, filename, (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW, &nd);
70		if (error)
71			goto out;
72
73		dentry = nd.dentry;
74	}
75
76	inode = dentry->d_inode;
77
78	error = -EROFS;
79	if (IS_RDONLY(inode))
80		goto dput_and_out;
81
82	/* Don't worry, the checks are done in inode_change_ok() */
83	newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
84	if (times) {
85		error = -EPERM;
86                if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
87                        goto dput_and_out;
88
89		if (times[0].tv_nsec == UTIME_OMIT)
90			newattrs.ia_valid &= ~ATTR_ATIME;
91		else if (times[0].tv_nsec != UTIME_NOW) {
92			newattrs.ia_atime.tv_sec = times[0].tv_sec;
93			newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
94			newattrs.ia_valid |= ATTR_ATIME_SET;
95		}
96
97		if (times[1].tv_nsec == UTIME_OMIT)
98			newattrs.ia_valid &= ~ATTR_MTIME;
99		else if (times[1].tv_nsec != UTIME_NOW) {
100			newattrs.ia_mtime.tv_sec = times[1].tv_sec;
101			newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
102			newattrs.ia_valid |= ATTR_MTIME_SET;
103		}
104	} else {
105		error = -EACCES;
106                if (IS_IMMUTABLE(inode))
107                        goto dput_and_out;
108
109		if (current->fsuid != inode->i_uid) {
110			if (f) {
111				if (!(f->f_mode & FMODE_WRITE))
112					goto dput_and_out;
113			} else {
114				error = vfs_permission(&nd, MAY_WRITE);
115				if (error)
116					goto dput_and_out;
117			}
118		}
119	}
120	mutex_lock(&inode->i_mutex);
121	error = notify_change(dentry, &newattrs);
122	mutex_unlock(&inode->i_mutex);
123dput_and_out:
124	if (f)
125		fput(f);
126	else
127		path_release(&nd);
128out:
129	return error;
130}
131
132asmlinkage long sys_utimensat(int dfd, char __user *filename, struct timespec __user *utimes, int flags)
133{
134	struct timespec tstimes[2];
135
136	if (utimes) {
137		if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
138			return -EFAULT;
139		if ((tstimes[0].tv_nsec == UTIME_OMIT ||
140		     tstimes[0].tv_nsec == UTIME_NOW) &&
141		    tstimes[0].tv_sec != 0)
142			return -EINVAL;
143		if ((tstimes[1].tv_nsec == UTIME_OMIT ||
144		     tstimes[1].tv_nsec == UTIME_NOW) &&
145		    tstimes[1].tv_sec != 0)
146			return -EINVAL;
147
148		/* Nothing to do, we must not even check the path.  */
149		if (tstimes[0].tv_nsec == UTIME_OMIT &&
150		    tstimes[1].tv_nsec == UTIME_OMIT)
151			return 0;
152	}
153
154	return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
155}
156
157asmlinkage long sys_futimesat(int dfd, char __user *filename, struct timeval __user *utimes)
158{
159	struct timeval times[2];
160	struct timespec tstimes[2];
161
162	if (utimes) {
163		if (copy_from_user(&times, utimes, sizeof(times)))
164			return -EFAULT;
165
166		/* This test is needed to catch all invalid values.  If we
167		   would test only in do_utimes we would miss those invalid
168		   values truncated by the multiplication with 1000.  Note
169		   that we also catch UTIME_{NOW,OMIT} here which are only
170		   valid for utimensat.  */
171		if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
172		    times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
173			return -EINVAL;
174
175		tstimes[0].tv_sec = times[0].tv_sec;
176		tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
177		tstimes[1].tv_sec = times[1].tv_sec;
178		tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
179	}
180
181	return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
182}
183
184asmlinkage long sys_utimes(char __user *filename, struct timeval __user *utimes)
185{
186	return sys_futimesat(AT_FDCWD, filename, utimes);
187}
188