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 */
27 SYSCALL_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, ×->actime) ||
33 get_user(tv[1].tv_sec, ×->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
43 static 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
51 static 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
57 error = mnt_want_write(path->mnt);
58 if (error)
59 goto out;
60
61 if (times && times[0].tv_nsec == UTIME_NOW &&
62 times[1].tv_nsec == UTIME_NOW)
63 times = NULL;
64
65 newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
66 if (times) {
67 if (times[0].tv_nsec == UTIME_OMIT)
68 newattrs.ia_valid &= ~ATTR_ATIME;
69 else if (times[0].tv_nsec != UTIME_NOW) {
70 newattrs.ia_atime.tv_sec = times[0].tv_sec;
71 newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
72 newattrs.ia_valid |= ATTR_ATIME_SET;
73 }
74
75 if (times[1].tv_nsec == UTIME_OMIT)
76 newattrs.ia_valid &= ~ATTR_MTIME;
77 else if (times[1].tv_nsec != UTIME_NOW) {
78 newattrs.ia_mtime.tv_sec = times[1].tv_sec;
79 newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
80 newattrs.ia_valid |= ATTR_MTIME_SET;
81 }
82 /*
83 * Tell inode_change_ok(), that this is an explicit time
84 * update, even if neither ATTR_ATIME_SET nor ATTR_MTIME_SET
85 * were used.
86 */
87 newattrs.ia_valid |= ATTR_TIMES_SET;
88 } else {
89 /*
90 * If times is NULL (or both times are UTIME_NOW),
91 * then we need to check permissions, because
92 * inode_change_ok() won't do it.
93 */
94 error = -EACCES;
95 if (IS_IMMUTABLE(inode))
96 goto mnt_drop_write_and_out;
97
98 if (!is_owner_or_cap(inode)) {
99 error = inode_permission(inode, MAY_WRITE);
100 if (error)
101 goto mnt_drop_write_and_out;
102 }
103 }
104 mutex_lock(&inode->i_mutex);
105 error = notify_change(path->dentry, &newattrs);
106 mutex_unlock(&inode->i_mutex);
107
108 mnt_drop_write_and_out:
109 mnt_drop_write(path->mnt);
110 out:
111 return error;
112 }
113
114 /*
115 * do_utimes - change times on filename or file descriptor
116 * @dfd: open file descriptor, -1 or AT_FDCWD
117 * @filename: path name or NULL
118 * @times: new times or NULL
119 * @flags: zero or more flags (only AT_SYMLINK_NOFOLLOW for the moment)
120 *
121 * If filename is NULL and dfd refers to an open file, then operate on
122 * the file. Otherwise look up filename, possibly using dfd as a
123 * starting point.
124 *
125 * If times==NULL, set access and modification to current time,
126 * must be owner or have write permission.
127 * Else, update from *times, must be owner or super user.
128 */
129 long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags)
130 {
131 int error = -EINVAL;
132
133 if (times && (!nsec_valid(times[0].tv_nsec) ||
134 !nsec_valid(times[1].tv_nsec))) {
135 goto out;
136 }
137
138 if (flags & ~AT_SYMLINK_NOFOLLOW)
139 goto out;
140
141 if (filename == NULL && dfd != AT_FDCWD) {
142 struct file *file;
143
144 if (flags & AT_SYMLINK_NOFOLLOW)
145 goto out;
146
147 file = fget(dfd);
148 error = -EBADF;
149 if (!file)
150 goto out;
151
152 error = utimes_common(&file->f_path, times);
153 fput(file);
154 } else {
155 struct path path;
156 int lookup_flags = 0;
157
158 if (!(flags & AT_SYMLINK_NOFOLLOW))
159 lookup_flags |= LOOKUP_FOLLOW;
160
161 error = user_path_at(dfd, filename, lookup_flags, &path);
162 if (error)
163 goto out;
164
165 error = utimes_common(&path, times);
166 path_put(&path);
167 }
168
169 out:
170 return error;
171 }
172
173 SYSCALL_DEFINE4(utimensat, int, dfd, char __user *, filename,
174 struct timespec __user *, utimes, int, flags)
175 {
176 struct timespec tstimes[2];
177
178 if (utimes) {
179 if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
180 return -EFAULT;
181
182 /* Nothing to do, we must not even check the path. */
183 if (tstimes[0].tv_nsec == UTIME_OMIT &&
184 tstimes[1].tv_nsec == UTIME_OMIT)
185 return 0;
186 }
187
188 return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
189 }
190
191 SYSCALL_DEFINE3(futimesat, int, dfd, char __user *, filename,
192 struct timeval __user *, utimes)
193 {
194 struct timeval times[2];
195 struct timespec tstimes[2];
196
197 if (utimes) {
198 if (copy_from_user(×, utimes, sizeof(times)))
199 return -EFAULT;
200
201 /* This test is needed to catch all invalid values. If we
202 would test only in do_utimes we would miss those invalid
203 values truncated by the multiplication with 1000. Note
204 that we also catch UTIME_{NOW,OMIT} here which are only
205 valid for utimensat. */
206 if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
207 times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
208 return -EINVAL;
209
210 tstimes[0].tv_sec = times[0].tv_sec;
211 tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
212 tstimes[1].tv_sec = times[1].tv_sec;
213 tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
214 }
215
216 return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
217 }
218
219 SYSCALL_DEFINE2(utimes, char __user *, filename,
220 struct timeval __user *, utimes)
221 {
222 return sys_futimesat(AT_FDCWD, filename, utimes);
223 }
224
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