[patch for 2.6.26 1/4] vfs: utimensat(): ignore tv_sec if tv_nsec == UTIME_OMIT or...
[linux-3.10.git] / fs / utimes.c
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 asmlinkage long sys_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_special(long nsec)
44 {
45         return nsec == UTIME_OMIT || nsec == UTIME_NOW;
46 }
47
48 static bool nsec_valid(long nsec)
49 {
50         if (nsec_special(nsec))
51                 return true;
52
53         return nsec >= 0 && nsec <= 999999999;
54 }
55
56 /* If times==NULL, set access and modification to current time,
57  * must be owner or have write permission.
58  * Else, update from *times, must be owner or super user.
59  */
60 long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags)
61 {
62         int error;
63         struct nameidata nd;
64         struct dentry *dentry;
65         struct inode *inode;
66         struct iattr newattrs;
67         struct file *f = NULL;
68         struct vfsmount *mnt;
69
70         error = -EINVAL;
71         if (times && (!nsec_valid(times[0].tv_nsec) ||
72                       !nsec_valid(times[1].tv_nsec))) {
73                 goto out;
74         }
75
76         if (flags & ~AT_SYMLINK_NOFOLLOW)
77                 goto out;
78
79         if (filename == NULL && dfd != AT_FDCWD) {
80                 error = -EINVAL;
81                 if (flags & AT_SYMLINK_NOFOLLOW)
82                         goto out;
83
84                 error = -EBADF;
85                 f = fget(dfd);
86                 if (!f)
87                         goto out;
88                 dentry = f->f_path.dentry;
89                 mnt = f->f_path.mnt;
90         } else {
91                 error = __user_walk_fd(dfd, filename, (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW, &nd);
92                 if (error)
93                         goto out;
94
95                 dentry = nd.path.dentry;
96                 mnt = nd.path.mnt;
97         }
98
99         inode = dentry->d_inode;
100
101         error = mnt_want_write(mnt);
102         if (error)
103                 goto dput_and_out;
104
105         if (times && times[0].tv_nsec == UTIME_NOW &&
106                      times[1].tv_nsec == UTIME_NOW)
107                 times = NULL;
108
109         /* Don't worry, the checks are done in inode_change_ok() */
110         newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
111         if (times) {
112                 error = -EPERM;
113                 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
114                         goto mnt_drop_write_and_out;
115
116                 if (times[0].tv_nsec == UTIME_OMIT)
117                         newattrs.ia_valid &= ~ATTR_ATIME;
118                 else if (times[0].tv_nsec != UTIME_NOW) {
119                         newattrs.ia_atime.tv_sec = times[0].tv_sec;
120                         newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
121                         newattrs.ia_valid |= ATTR_ATIME_SET;
122                 }
123
124                 if (times[1].tv_nsec == UTIME_OMIT)
125                         newattrs.ia_valid &= ~ATTR_MTIME;
126                 else if (times[1].tv_nsec != UTIME_NOW) {
127                         newattrs.ia_mtime.tv_sec = times[1].tv_sec;
128                         newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
129                         newattrs.ia_valid |= ATTR_MTIME_SET;
130                 }
131         }
132
133         /*
134          * If times is NULL or both times are either UTIME_OMIT or
135          * UTIME_NOW, then need to check permissions, because
136          * inode_change_ok() won't do it.
137          */
138         if (!times || (nsec_special(times[0].tv_nsec) &&
139                        nsec_special(times[1].tv_nsec))) {
140                 error = -EACCES;
141                 if (IS_IMMUTABLE(inode))
142                         goto mnt_drop_write_and_out;
143
144                 if (!is_owner_or_cap(inode)) {
145                         if (f) {
146                                 if (!(f->f_mode & FMODE_WRITE))
147                                         goto mnt_drop_write_and_out;
148                         } else {
149                                 error = vfs_permission(&nd, MAY_WRITE);
150                                 if (error)
151                                         goto mnt_drop_write_and_out;
152                         }
153                 }
154         }
155         mutex_lock(&inode->i_mutex);
156         error = notify_change(dentry, &newattrs);
157         mutex_unlock(&inode->i_mutex);
158 mnt_drop_write_and_out:
159         mnt_drop_write(mnt);
160 dput_and_out:
161         if (f)
162                 fput(f);
163         else
164                 path_put(&nd.path);
165 out:
166         return error;
167 }
168
169 asmlinkage long sys_utimensat(int dfd, char __user *filename, struct timespec __user *utimes, int flags)
170 {
171         struct timespec tstimes[2];
172
173         if (utimes) {
174                 if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
175                         return -EFAULT;
176
177                 /* Nothing to do, we must not even check the path.  */
178                 if (tstimes[0].tv_nsec == UTIME_OMIT &&
179                     tstimes[1].tv_nsec == UTIME_OMIT)
180                         return 0;
181         }
182
183         return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
184 }
185
186 asmlinkage long sys_futimesat(int dfd, char __user *filename, struct timeval __user *utimes)
187 {
188         struct timeval times[2];
189         struct timespec tstimes[2];
190
191         if (utimes) {
192                 if (copy_from_user(&times, utimes, sizeof(times)))
193                         return -EFAULT;
194
195                 /* This test is needed to catch all invalid values.  If we
196                    would test only in do_utimes we would miss those invalid
197                    values truncated by the multiplication with 1000.  Note
198                    that we also catch UTIME_{NOW,OMIT} here which are only
199                    valid for utimensat.  */
200                 if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
201                     times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
202                         return -EINVAL;
203
204                 tstimes[0].tv_sec = times[0].tv_sec;
205                 tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
206                 tstimes[1].tv_sec = times[1].tv_sec;
207                 tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
208         }
209
210         return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
211 }
212
213 asmlinkage long sys_utimes(char __user *filename, struct timeval __user *utimes)
214 {
215         return sys_futimesat(AT_FDCWD, filename, utimes);
216 }