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