xref: /openbmc/linux/fs/utimes.c (revision c21b37f6)
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 /* If times==NULL, set access and modification to current time,
42  * must be owner or have write permission.
43  * Else, update from *times, must be owner or super user.
44  */
45 long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags)
46 {
47 	int error;
48 	struct nameidata nd;
49 	struct dentry *dentry;
50 	struct inode *inode;
51 	struct iattr newattrs;
52 	struct file *f = NULL;
53 
54 	error = -EINVAL;
55 	if (flags & ~AT_SYMLINK_NOFOLLOW)
56 		goto out;
57 
58 	if (filename == NULL && dfd != AT_FDCWD) {
59 		error = -EINVAL;
60 		if (flags & AT_SYMLINK_NOFOLLOW)
61 			goto out;
62 
63 		error = -EBADF;
64 		f = fget(dfd);
65 		if (!f)
66 			goto out;
67 		dentry = f->f_path.dentry;
68 	} else {
69 		error = __user_walk_fd(dfd, filename, (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW, &nd);
70 		if (error)
71 			goto out;
72 
73 		dentry = nd.dentry;
74 	}
75 
76 	inode = dentry->d_inode;
77 
78 	error = -EROFS;
79 	if (IS_RDONLY(inode))
80 		goto dput_and_out;
81 
82 	/* Don't worry, the checks are done in inode_change_ok() */
83 	newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
84 	if (times) {
85 		error = -EPERM;
86                 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
87                         goto dput_and_out;
88 
89 		if (times[0].tv_nsec == UTIME_OMIT)
90 			newattrs.ia_valid &= ~ATTR_ATIME;
91 		else if (times[0].tv_nsec != UTIME_NOW) {
92 			newattrs.ia_atime.tv_sec = times[0].tv_sec;
93 			newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
94 			newattrs.ia_valid |= ATTR_ATIME_SET;
95 		}
96 
97 		if (times[1].tv_nsec == UTIME_OMIT)
98 			newattrs.ia_valid &= ~ATTR_MTIME;
99 		else if (times[1].tv_nsec != UTIME_NOW) {
100 			newattrs.ia_mtime.tv_sec = times[1].tv_sec;
101 			newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
102 			newattrs.ia_valid |= ATTR_MTIME_SET;
103 		}
104 	} else {
105 		error = -EACCES;
106                 if (IS_IMMUTABLE(inode))
107                         goto dput_and_out;
108 
109 		if (!is_owner_or_cap(inode)) {
110 			if (f) {
111 				if (!(f->f_mode & FMODE_WRITE))
112 					goto dput_and_out;
113 			} else {
114 				error = vfs_permission(&nd, MAY_WRITE);
115 				if (error)
116 					goto dput_and_out;
117 			}
118 		}
119 	}
120 	mutex_lock(&inode->i_mutex);
121 	error = notify_change(dentry, &newattrs);
122 	mutex_unlock(&inode->i_mutex);
123 dput_and_out:
124 	if (f)
125 		fput(f);
126 	else
127 		path_release(&nd);
128 out:
129 	return error;
130 }
131 
132 asmlinkage long sys_utimensat(int dfd, char __user *filename, struct timespec __user *utimes, int flags)
133 {
134 	struct timespec tstimes[2];
135 
136 	if (utimes) {
137 		if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
138 			return -EFAULT;
139 		if ((tstimes[0].tv_nsec == UTIME_OMIT ||
140 		     tstimes[0].tv_nsec == UTIME_NOW) &&
141 		    tstimes[0].tv_sec != 0)
142 			return -EINVAL;
143 		if ((tstimes[1].tv_nsec == UTIME_OMIT ||
144 		     tstimes[1].tv_nsec == UTIME_NOW) &&
145 		    tstimes[1].tv_sec != 0)
146 			return -EINVAL;
147 
148 		/* Nothing to do, we must not even check the path.  */
149 		if (tstimes[0].tv_nsec == UTIME_OMIT &&
150 		    tstimes[1].tv_nsec == UTIME_OMIT)
151 			return 0;
152 	}
153 
154 	return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
155 }
156 
157 asmlinkage long sys_futimesat(int dfd, char __user *filename, struct timeval __user *utimes)
158 {
159 	struct timeval times[2];
160 	struct timespec tstimes[2];
161 
162 	if (utimes) {
163 		if (copy_from_user(&times, utimes, sizeof(times)))
164 			return -EFAULT;
165 
166 		/* This test is needed to catch all invalid values.  If we
167 		   would test only in do_utimes we would miss those invalid
168 		   values truncated by the multiplication with 1000.  Note
169 		   that we also catch UTIME_{NOW,OMIT} here which are only
170 		   valid for utimensat.  */
171 		if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
172 		    times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
173 			return -EINVAL;
174 
175 		tstimes[0].tv_sec = times[0].tv_sec;
176 		tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
177 		tstimes[1].tv_sec = times[1].tv_sec;
178 		tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
179 	}
180 
181 	return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
182 }
183 
184 asmlinkage long sys_utimes(char __user *filename, struct timeval __user *utimes)
185 {
186 	return sys_futimesat(AT_FDCWD, filename, utimes);
187 }
188