b9912ecbee241231ca0b776d9131af1e2643d80a
[linux-2.6.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/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  */
25 asmlinkage 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 static bool nsec_valid(long nsec)
42 {
43         if (nsec == UTIME_OMIT || nsec == UTIME_NOW)
44                 return true;
45
46         return nsec >= 0 && nsec <= 999999999;
47 }
48
49 /* If times==NULL, set access and modification to current time,
50  * must be owner or have write permission.
51  * Else, update from *times, must be owner or super user.
52  */
53 long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags)
54 {
55         int error;
56         struct nameidata nd;
57         struct dentry *dentry;
58         struct inode *inode;
59         struct iattr newattrs;
60         struct file *f = NULL;
61
62         error = -EINVAL;
63         if (times && (!nsec_valid(times[0].tv_nsec) ||
64                       !nsec_valid(times[1].tv_nsec))) {
65                 goto out;
66         }
67
68         if (flags & ~AT_SYMLINK_NOFOLLOW)
69                 goto out;
70
71         if (filename == NULL && dfd != AT_FDCWD) {
72                 error = -EINVAL;
73                 if (flags & AT_SYMLINK_NOFOLLOW)
74                         goto out;
75
76                 error = -EBADF;
77                 f = fget(dfd);
78                 if (!f)
79                         goto out;
80                 dentry = f->f_path.dentry;
81         } else {
82                 error = __user_walk_fd(dfd, filename, (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW, &nd);
83                 if (error)
84                         goto out;
85
86                 dentry = nd.dentry;
87         }
88
89         inode = dentry->d_inode;
90
91         error = -EROFS;
92         if (IS_RDONLY(inode))
93                 goto dput_and_out;
94
95         /* Don't worry, the checks are done in inode_change_ok() */
96         newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
97         if (times) {
98                 error = -EPERM;
99                 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
100                         goto dput_and_out;
101
102                 if (times[0].tv_nsec == UTIME_OMIT)
103                         newattrs.ia_valid &= ~ATTR_ATIME;
104                 else if (times[0].tv_nsec != UTIME_NOW) {
105                         newattrs.ia_atime.tv_sec = times[0].tv_sec;
106                         newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
107                         newattrs.ia_valid |= ATTR_ATIME_SET;
108                 }
109
110                 if (times[1].tv_nsec == UTIME_OMIT)
111                         newattrs.ia_valid &= ~ATTR_MTIME;
112                 else if (times[1].tv_nsec != UTIME_NOW) {
113                         newattrs.ia_mtime.tv_sec = times[1].tv_sec;
114                         newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
115                         newattrs.ia_valid |= ATTR_MTIME_SET;
116                 }
117         } else {
118                 error = -EACCES;
119                 if (IS_IMMUTABLE(inode))
120                         goto dput_and_out;
121
122                 if (!is_owner_or_cap(inode)) {
123                         if (f) {
124                                 if (!(f->f_mode & FMODE_WRITE))
125                                         goto dput_and_out;
126                         } else {
127                                 error = vfs_permission(&nd, MAY_WRITE);
128                                 if (error)
129                                         goto dput_and_out;
130                         }
131                 }
132         }
133         mutex_lock(&inode->i_mutex);
134         error = notify_change(dentry, &newattrs);
135         mutex_unlock(&inode->i_mutex);
136 dput_and_out:
137         if (f)
138                 fput(f);
139         else
140                 path_release(&nd);
141 out:
142         return error;
143 }
144
145 asmlinkage long sys_utimensat(int dfd, char __user *filename, struct timespec __user *utimes, int flags)
146 {
147         struct timespec tstimes[2];
148
149         if (utimes) {
150                 if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
151                         return -EFAULT;
152                 if ((tstimes[0].tv_nsec == UTIME_OMIT ||
153                      tstimes[0].tv_nsec == UTIME_NOW) &&
154                     tstimes[0].tv_sec != 0)
155                         return -EINVAL;
156                 if ((tstimes[1].tv_nsec == UTIME_OMIT ||
157                      tstimes[1].tv_nsec == UTIME_NOW) &&
158                     tstimes[1].tv_sec != 0)
159                         return -EINVAL;
160
161                 /* Nothing to do, we must not even check the path.  */
162                 if (tstimes[0].tv_nsec == UTIME_OMIT &&
163                     tstimes[1].tv_nsec == UTIME_OMIT)
164                         return 0;
165         }
166
167         return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
168 }
169
170 asmlinkage long sys_futimesat(int dfd, char __user *filename, struct timeval __user *utimes)
171 {
172         struct timeval times[2];
173         struct timespec tstimes[2];
174
175         if (utimes) {
176                 if (copy_from_user(&times, utimes, sizeof(times)))
177                         return -EFAULT;
178
179                 /* This test is needed to catch all invalid values.  If we
180                    would test only in do_utimes we would miss those invalid
181                    values truncated by the multiplication with 1000.  Note
182                    that we also catch UTIME_{NOW,OMIT} here which are only
183                    valid for utimensat.  */
184                 if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
185                     times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
186                         return -EINVAL;
187
188                 tstimes[0].tv_sec = times[0].tv_sec;
189                 tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
190                 tstimes[1].tv_sec = times[1].tv_sec;
191                 tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
192         }
193
194         return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
195 }
196
197 asmlinkage long sys_utimes(char __user *filename, struct timeval __user *utimes)
198 {
199         return sys_futimesat(AT_FDCWD, filename, utimes);
200 }