Introduce path_put()
[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 <linux/syscalls.h>
10 #include <asm/uaccess.h>
11 #include <asm/unistd.h>
12
13 #ifdef __ARCH_WANT_SYS_UTIME
14
15 /*
16  * sys_utime() can be implemented in user-level using sys_utimes().
17  * Is this for backwards compatibility?  If so, why not move it
18  * into the appropriate arch directory (for those architectures that
19  * need it).
20  */
21
22 /* If times==NULL, set access and modification to current time,
23  * must be owner or have write permission.
24  * Else, update from *times, must be owner or super user.
25  */
26 asmlinkage long sys_utime(char __user *filename, struct utimbuf __user *times)
27 {
28         struct timespec tv[2];
29
30         if (times) {
31                 if (get_user(tv[0].tv_sec, &times->actime) ||
32                     get_user(tv[1].tv_sec, &times->modtime))
33                         return -EFAULT;
34                 tv[0].tv_nsec = 0;
35                 tv[1].tv_nsec = 0;
36         }
37         return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
38 }
39
40 #endif
41
42 static bool nsec_valid(long nsec)
43 {
44         if (nsec == UTIME_OMIT || nsec == UTIME_NOW)
45                 return true;
46
47         return nsec >= 0 && nsec <= 999999999;
48 }
49
50 /* If times==NULL, set access and modification to current time,
51  * must be owner or have write permission.
52  * Else, update from *times, must be owner or super user.
53  */
54 long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags)
55 {
56         int error;
57         struct nameidata nd;
58         struct dentry *dentry;
59         struct inode *inode;
60         struct iattr newattrs;
61         struct file *f = NULL;
62
63         error = -EINVAL;
64         if (times && (!nsec_valid(times[0].tv_nsec) ||
65                       !nsec_valid(times[1].tv_nsec))) {
66                 goto out;
67         }
68
69         if (flags & ~AT_SYMLINK_NOFOLLOW)
70                 goto out;
71
72         if (filename == NULL && dfd != AT_FDCWD) {
73                 error = -EINVAL;
74                 if (flags & AT_SYMLINK_NOFOLLOW)
75                         goto out;
76
77                 error = -EBADF;
78                 f = fget(dfd);
79                 if (!f)
80                         goto out;
81                 dentry = f->f_path.dentry;
82         } else {
83                 error = __user_walk_fd(dfd, filename, (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW, &nd);
84                 if (error)
85                         goto out;
86
87                 dentry = nd.path.dentry;
88         }
89
90         inode = dentry->d_inode;
91
92         error = -EROFS;
93         if (IS_RDONLY(inode))
94                 goto dput_and_out;
95
96         /* Don't worry, the checks are done in inode_change_ok() */
97         newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
98         if (times) {
99                 error = -EPERM;
100                 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
101                         goto dput_and_out;
102
103                 if (times[0].tv_nsec == UTIME_OMIT)
104                         newattrs.ia_valid &= ~ATTR_ATIME;
105                 else if (times[0].tv_nsec != UTIME_NOW) {
106                         newattrs.ia_atime.tv_sec = times[0].tv_sec;
107                         newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
108                         newattrs.ia_valid |= ATTR_ATIME_SET;
109                 }
110
111                 if (times[1].tv_nsec == UTIME_OMIT)
112                         newattrs.ia_valid &= ~ATTR_MTIME;
113                 else if (times[1].tv_nsec != UTIME_NOW) {
114                         newattrs.ia_mtime.tv_sec = times[1].tv_sec;
115                         newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
116                         newattrs.ia_valid |= ATTR_MTIME_SET;
117                 }
118         } else {
119                 error = -EACCES;
120                 if (IS_IMMUTABLE(inode))
121                         goto dput_and_out;
122
123                 if (!is_owner_or_cap(inode)) {
124                         if (f) {
125                                 if (!(f->f_mode & FMODE_WRITE))
126                                         goto dput_and_out;
127                         } else {
128                                 error = vfs_permission(&nd, MAY_WRITE);
129                                 if (error)
130                                         goto dput_and_out;
131                         }
132                 }
133         }
134         mutex_lock(&inode->i_mutex);
135         error = notify_change(dentry, &newattrs);
136         mutex_unlock(&inode->i_mutex);
137 dput_and_out:
138         if (f)
139                 fput(f);
140         else
141                 path_put(&nd.path);
142 out:
143         return error;
144 }
145
146 asmlinkage long sys_utimensat(int dfd, char __user *filename, struct timespec __user *utimes, int flags)
147 {
148         struct timespec tstimes[2];
149
150         if (utimes) {
151                 if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
152                         return -EFAULT;
153                 if ((tstimes[0].tv_nsec == UTIME_OMIT ||
154                      tstimes[0].tv_nsec == UTIME_NOW) &&
155                     tstimes[0].tv_sec != 0)
156                         return -EINVAL;
157                 if ((tstimes[1].tv_nsec == UTIME_OMIT ||
158                      tstimes[1].tv_nsec == UTIME_NOW) &&
159                     tstimes[1].tv_sec != 0)
160                         return -EINVAL;
161
162                 /* Nothing to do, we must not even check the path.  */
163                 if (tstimes[0].tv_nsec == UTIME_OMIT &&
164                     tstimes[1].tv_nsec == UTIME_OMIT)
165                         return 0;
166         }
167
168         return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
169 }
170
171 asmlinkage long sys_futimesat(int dfd, char __user *filename, struct timeval __user *utimes)
172 {
173         struct timeval times[2];
174         struct timespec tstimes[2];
175
176         if (utimes) {
177                 if (copy_from_user(&times, utimes, sizeof(times)))
178                         return -EFAULT;
179
180                 /* This test is needed to catch all invalid values.  If we
181                    would test only in do_utimes we would miss those invalid
182                    values truncated by the multiplication with 1000.  Note
183                    that we also catch UTIME_{NOW,OMIT} here which are only
184                    valid for utimensat.  */
185                 if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
186                     times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
187                         return -EINVAL;
188
189                 tstimes[0].tv_sec = times[0].tv_sec;
190                 tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
191                 tstimes[1].tv_sec = times[1].tv_sec;
192                 tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
193         }
194
195         return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
196 }
197
198 asmlinkage long sys_utimes(char __user *filename, struct timeval __user *utimes)
199 {
200         return sys_futimesat(AT_FDCWD, filename, utimes);
201 }