1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/file.h>
3 #include <linux/mount.h>
4 #include <linux/namei.h>
5 #include <linux/utime.h>
6 #include <linux/syscalls.h>
7 #include <linux/uaccess.h>
8 #include <linux/compat.h>
9 #include <asm/unistd.h>
10 
nsec_valid(long nsec)11 static bool nsec_valid(long nsec)
12 {
13 	if (nsec == UTIME_OMIT || nsec == UTIME_NOW)
14 		return true;
15 
16 	return nsec >= 0 && nsec <= 999999999;
17 }
18 
vfs_utimes(const struct path * path,struct timespec64 * times)19 int vfs_utimes(const struct path *path, struct timespec64 *times)
20 {
21 	int error;
22 	struct iattr newattrs;
23 	struct inode *inode = path->dentry->d_inode;
24 	struct inode *delegated_inode = NULL;
25 
26 	if (times) {
27 		if (!nsec_valid(times[0].tv_nsec) ||
28 		    !nsec_valid(times[1].tv_nsec))
29 			return -EINVAL;
30 		if (times[0].tv_nsec == UTIME_NOW &&
31 		    times[1].tv_nsec == UTIME_NOW)
32 			times = NULL;
33 	}
34 
35 	error = mnt_want_write(path->mnt);
36 	if (error)
37 		goto out;
38 
39 	newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
40 	if (times) {
41 		if (times[0].tv_nsec == UTIME_OMIT)
42 			newattrs.ia_valid &= ~ATTR_ATIME;
43 		else if (times[0].tv_nsec != UTIME_NOW) {
44 			newattrs.ia_atime = times[0];
45 			newattrs.ia_valid |= ATTR_ATIME_SET;
46 		}
47 
48 		if (times[1].tv_nsec == UTIME_OMIT)
49 			newattrs.ia_valid &= ~ATTR_MTIME;
50 		else if (times[1].tv_nsec != UTIME_NOW) {
51 			newattrs.ia_mtime = times[1];
52 			newattrs.ia_valid |= ATTR_MTIME_SET;
53 		}
54 		/*
55 		 * Tell setattr_prepare(), that this is an explicit time
56 		 * update, even if neither ATTR_ATIME_SET nor ATTR_MTIME_SET
57 		 * were used.
58 		 */
59 		newattrs.ia_valid |= ATTR_TIMES_SET;
60 	} else {
61 		newattrs.ia_valid |= ATTR_TOUCH;
62 	}
63 retry_deleg:
64 	inode_lock(inode);
65 	error = notify_change(mnt_user_ns(path->mnt), path->dentry, &newattrs,
66 			      &delegated_inode);
67 	inode_unlock(inode);
68 	if (delegated_inode) {
69 		error = break_deleg_wait(&delegated_inode);
70 		if (!error)
71 			goto retry_deleg;
72 	}
73 
74 	mnt_drop_write(path->mnt);
75 out:
76 	return error;
77 }
78 
do_utimes_path(int dfd,const char __user * filename,struct timespec64 * times,int flags)79 static int do_utimes_path(int dfd, const char __user *filename,
80 		struct timespec64 *times, int flags)
81 {
82 	struct path path;
83 	int lookup_flags = 0, error;
84 
85 	if (flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
86 		return -EINVAL;
87 
88 	if (!(flags & AT_SYMLINK_NOFOLLOW))
89 		lookup_flags |= LOOKUP_FOLLOW;
90 	if (flags & AT_EMPTY_PATH)
91 		lookup_flags |= LOOKUP_EMPTY;
92 
93 retry:
94 	error = user_path_at(dfd, filename, lookup_flags, &path);
95 	if (error)
96 		return error;
97 
98 	error = vfs_utimes(&path, times);
99 	path_put(&path);
100 	if (retry_estale(error, lookup_flags)) {
101 		lookup_flags |= LOOKUP_REVAL;
102 		goto retry;
103 	}
104 
105 	return error;
106 }
107 
do_utimes_fd(int fd,struct timespec64 * times,int flags)108 static int do_utimes_fd(int fd, struct timespec64 *times, int flags)
109 {
110 	struct fd f;
111 	int error;
112 
113 	if (flags)
114 		return -EINVAL;
115 
116 	f = fdget(fd);
117 	if (!f.file)
118 		return -EBADF;
119 	error = vfs_utimes(&f.file->f_path, times);
120 	fdput(f);
121 	return error;
122 }
123 
124 /*
125  * do_utimes - change times on filename or file descriptor
126  * @dfd: open file descriptor, -1 or AT_FDCWD
127  * @filename: path name or NULL
128  * @times: new times or NULL
129  * @flags: zero or more flags (only AT_SYMLINK_NOFOLLOW for the moment)
130  *
131  * If filename is NULL and dfd refers to an open file, then operate on
132  * the file.  Otherwise look up filename, possibly using dfd as a
133  * starting point.
134  *
135  * If times==NULL, set access and modification to current time,
136  * must be owner or have write permission.
137  * Else, update from *times, must be owner or super user.
138  */
do_utimes(int dfd,const char __user * filename,struct timespec64 * times,int flags)139 long do_utimes(int dfd, const char __user *filename, struct timespec64 *times,
140 	       int flags)
141 {
142 	if (filename == NULL && dfd != AT_FDCWD)
143 		return do_utimes_fd(dfd, times, flags);
144 	return do_utimes_path(dfd, filename, times, flags);
145 }
146 
SYSCALL_DEFINE4(utimensat,int,dfd,const char __user *,filename,struct __kernel_timespec __user *,utimes,int,flags)147 SYSCALL_DEFINE4(utimensat, int, dfd, const char __user *, filename,
148 		struct __kernel_timespec __user *, utimes, int, flags)
149 {
150 	struct timespec64 tstimes[2];
151 
152 	if (utimes) {
153 		if ((get_timespec64(&tstimes[0], &utimes[0]) ||
154 			get_timespec64(&tstimes[1], &utimes[1])))
155 			return -EFAULT;
156 
157 		/* Nothing to do, we must not even check the path.  */
158 		if (tstimes[0].tv_nsec == UTIME_OMIT &&
159 		    tstimes[1].tv_nsec == UTIME_OMIT)
160 			return 0;
161 	}
162 
163 	return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
164 }
165 
166 #ifdef __ARCH_WANT_SYS_UTIME
167 /*
168  * futimesat(), utimes() and utime() are older versions of utimensat()
169  * that are provided for compatibility with traditional C libraries.
170  * On modern architectures, we always use libc wrappers around
171  * utimensat() instead.
172  */
do_futimesat(int dfd,const char __user * filename,struct __kernel_old_timeval __user * utimes)173 static long do_futimesat(int dfd, const char __user *filename,
174 			 struct __kernel_old_timeval __user *utimes)
175 {
176 	struct __kernel_old_timeval times[2];
177 	struct timespec64 tstimes[2];
178 
179 	if (utimes) {
180 		if (copy_from_user(&times, utimes, sizeof(times)))
181 			return -EFAULT;
182 
183 		/* This test is needed to catch all invalid values.  If we
184 		   would test only in do_utimes we would miss those invalid
185 		   values truncated by the multiplication with 1000.  Note
186 		   that we also catch UTIME_{NOW,OMIT} here which are only
187 		   valid for utimensat.  */
188 		if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
189 		    times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
190 			return -EINVAL;
191 
192 		tstimes[0].tv_sec = times[0].tv_sec;
193 		tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
194 		tstimes[1].tv_sec = times[1].tv_sec;
195 		tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
196 	}
197 
198 	return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
199 }
200 
201 
SYSCALL_DEFINE3(futimesat,int,dfd,const char __user *,filename,struct __kernel_old_timeval __user *,utimes)202 SYSCALL_DEFINE3(futimesat, int, dfd, const char __user *, filename,
203 		struct __kernel_old_timeval __user *, utimes)
204 {
205 	return do_futimesat(dfd, filename, utimes);
206 }
207 
SYSCALL_DEFINE2(utimes,char __user *,filename,struct __kernel_old_timeval __user *,utimes)208 SYSCALL_DEFINE2(utimes, char __user *, filename,
209 		struct __kernel_old_timeval __user *, utimes)
210 {
211 	return do_futimesat(AT_FDCWD, filename, utimes);
212 }
213 
SYSCALL_DEFINE2(utime,char __user *,filename,struct utimbuf __user *,times)214 SYSCALL_DEFINE2(utime, char __user *, filename, struct utimbuf __user *, times)
215 {
216 	struct timespec64 tv[2];
217 
218 	if (times) {
219 		if (get_user(tv[0].tv_sec, &times->actime) ||
220 		    get_user(tv[1].tv_sec, &times->modtime))
221 			return -EFAULT;
222 		tv[0].tv_nsec = 0;
223 		tv[1].tv_nsec = 0;
224 	}
225 	return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
226 }
227 #endif
228 
229 #ifdef CONFIG_COMPAT_32BIT_TIME
230 /*
231  * Not all architectures have sys_utime, so implement this in terms
232  * of sys_utimes.
233  */
234 #ifdef __ARCH_WANT_SYS_UTIME32
SYSCALL_DEFINE2(utime32,const char __user *,filename,struct old_utimbuf32 __user *,t)235 SYSCALL_DEFINE2(utime32, const char __user *, filename,
236 		struct old_utimbuf32 __user *, t)
237 {
238 	struct timespec64 tv[2];
239 
240 	if (t) {
241 		if (get_user(tv[0].tv_sec, &t->actime) ||
242 		    get_user(tv[1].tv_sec, &t->modtime))
243 			return -EFAULT;
244 		tv[0].tv_nsec = 0;
245 		tv[1].tv_nsec = 0;
246 	}
247 	return do_utimes(AT_FDCWD, filename, t ? tv : NULL, 0);
248 }
249 #endif
250 
SYSCALL_DEFINE4(utimensat_time32,unsigned int,dfd,const char __user *,filename,struct old_timespec32 __user *,t,int,flags)251 SYSCALL_DEFINE4(utimensat_time32, unsigned int, dfd, const char __user *, filename, struct old_timespec32 __user *, t, int, flags)
252 {
253 	struct timespec64 tv[2];
254 
255 	if  (t) {
256 		if (get_old_timespec32(&tv[0], &t[0]) ||
257 		    get_old_timespec32(&tv[1], &t[1]))
258 			return -EFAULT;
259 
260 		if (tv[0].tv_nsec == UTIME_OMIT && tv[1].tv_nsec == UTIME_OMIT)
261 			return 0;
262 	}
263 	return do_utimes(dfd, filename, t ? tv : NULL, flags);
264 }
265 
266 #ifdef __ARCH_WANT_SYS_UTIME32
do_compat_futimesat(unsigned int dfd,const char __user * filename,struct old_timeval32 __user * t)267 static long do_compat_futimesat(unsigned int dfd, const char __user *filename,
268 				struct old_timeval32 __user *t)
269 {
270 	struct timespec64 tv[2];
271 
272 	if (t) {
273 		if (get_user(tv[0].tv_sec, &t[0].tv_sec) ||
274 		    get_user(tv[0].tv_nsec, &t[0].tv_usec) ||
275 		    get_user(tv[1].tv_sec, &t[1].tv_sec) ||
276 		    get_user(tv[1].tv_nsec, &t[1].tv_usec))
277 			return -EFAULT;
278 		if (tv[0].tv_nsec >= 1000000 || tv[0].tv_nsec < 0 ||
279 		    tv[1].tv_nsec >= 1000000 || tv[1].tv_nsec < 0)
280 			return -EINVAL;
281 		tv[0].tv_nsec *= 1000;
282 		tv[1].tv_nsec *= 1000;
283 	}
284 	return do_utimes(dfd, filename, t ? tv : NULL, 0);
285 }
286 
SYSCALL_DEFINE3(futimesat_time32,unsigned int,dfd,const char __user *,filename,struct old_timeval32 __user *,t)287 SYSCALL_DEFINE3(futimesat_time32, unsigned int, dfd,
288 		       const char __user *, filename,
289 		       struct old_timeval32 __user *, t)
290 {
291 	return do_compat_futimesat(dfd, filename, t);
292 }
293 
SYSCALL_DEFINE2(utimes_time32,const char __user *,filename,struct old_timeval32 __user *,t)294 SYSCALL_DEFINE2(utimes_time32, const char __user *, filename, struct old_timeval32 __user *, t)
295 {
296 	return do_compat_futimesat(AT_FDCWD, filename, t);
297 }
298 #endif
299 #endif
300