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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, &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
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 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 }
105 retry_deleg:
106 inode_lock(inode);
107 error = notify_change(path->dentry, &newattrs, &delegated_inode);
108 inode_unlock(inode);
109 if (delegated_inode) {
110 error = break_deleg_wait(&delegated_inode);
111 if (!error)
112 goto retry_deleg;
113 }
114
115 mnt_drop_write_and_out:
116 mnt_drop_write(path->mnt);
117 out:
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 */
136 long 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;
168 retry:
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
181 out:
182 return error;
183 }
184
185 SYSCALL_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
203 SYSCALL_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
231 SYSCALL_DEFINE2(utimes, char __user *, filename,
232 struct timeval __user *, utimes)
233 {
234 return sys_futimesat(AT_FDCWD, filename, utimes);
235 }