1 /*
2  *  arch/arm/kernel/sys_oabi-compat.c
3  *
4  *  Compatibility wrappers for syscalls that are used from
5  *  old ABI user space binaries with an EABI kernel.
6  *
7  *  Author:	Nicolas Pitre
8  *  Created:	Oct 7, 2005
9  *  Copyright:	MontaVista Software, Inc.
10  *
11  *  This program is free software; you can redistribute it and/or modify
12  *  it under the terms of the GNU General Public License version 2 as
13  *  published by the Free Software Foundation.
14  */
15 
16 /*
17  * The legacy ABI and the new ARM EABI have different rules making some
18  * syscalls incompatible especially with structure arguments.
19  * Most notably, Eabi says 64-bit members should be 64-bit aligned instead of
20  * simply word aligned.  EABI also pads structures to the size of the largest
21  * member it contains instead of the invariant 32-bit.
22  *
23  * The following syscalls are affected:
24  *
25  * sys_stat64:
26  * sys_lstat64:
27  * sys_fstat64:
28  * sys_fstatat64:
29  *
30  *   struct stat64 has different sizes and some members are shifted
31  *   Compatibility wrappers are needed for them and provided below.
32  *
33  * sys_fcntl64:
34  *
35  *   struct flock64 has different sizes and some members are shifted
36  *   A compatibility wrapper is needed and provided below.
37  *
38  * sys_statfs64:
39  * sys_fstatfs64:
40  *
41  *   struct statfs64 has extra padding with EABI growing its size from
42  *   84 to 88.  This struct is now __attribute__((packed,aligned(4)))
43  *   with a small assembly wrapper to force the sz argument to 84 if it is 88
44  *   to avoid copying the extra padding over user space unexpecting it.
45  *
46  * sys_newuname:
47  *
48  *   struct new_utsname has no padding with EABI.  No problem there.
49  *
50  * sys_epoll_ctl:
51  * sys_epoll_wait:
52  *
53  *   struct epoll_event has its second member shifted also affecting the
54  *   structure size. Compatibility wrappers are needed and provided below.
55  *
56  * sys_ipc:
57  * sys_semop:
58  * sys_semtimedop:
59  *
60  *   struct sembuf loses its padding with EABI.  Since arrays of them are
61  *   used they have to be copyed to remove the padding. Compatibility wrappers
62  *   provided below.
63  *
64  * sys_bind:
65  * sys_connect:
66  * sys_sendmsg:
67  * sys_sendto:
68  * sys_socketcall:
69  *
70  *   struct sockaddr_un loses its padding with EABI.  Since the size of the
71  *   structure is used as a validation test in unix_mkname(), we need to
72  *   change the length argument to 110 whenever it is 112.  Compatibility
73  *   wrappers provided below.
74  */
75 
76 #include <linux/syscalls.h>
77 #include <linux/errno.h>
78 #include <linux/fs.h>
79 #include <linux/cred.h>
80 #include <linux/fcntl.h>
81 #include <linux/eventpoll.h>
82 #include <linux/sem.h>
83 #include <linux/socket.h>
84 #include <linux/net.h>
85 #include <linux/ipc.h>
86 #include <linux/uaccess.h>
87 #include <linux/slab.h>
88 
89 struct oldabi_stat64 {
90 	unsigned long long st_dev;
91 	unsigned int	__pad1;
92 	unsigned long	__st_ino;
93 	unsigned int	st_mode;
94 	unsigned int	st_nlink;
95 
96 	unsigned long	st_uid;
97 	unsigned long	st_gid;
98 
99 	unsigned long long st_rdev;
100 	unsigned int	__pad2;
101 
102 	long long	st_size;
103 	unsigned long	st_blksize;
104 	unsigned long long st_blocks;
105 
106 	unsigned long	st_atime;
107 	unsigned long	st_atime_nsec;
108 
109 	unsigned long	st_mtime;
110 	unsigned long	st_mtime_nsec;
111 
112 	unsigned long	st_ctime;
113 	unsigned long	st_ctime_nsec;
114 
115 	unsigned long long st_ino;
116 } __attribute__ ((packed,aligned(4)));
117 
118 static long cp_oldabi_stat64(struct kstat *stat,
119 			     struct oldabi_stat64 __user *statbuf)
120 {
121 	struct oldabi_stat64 tmp;
122 
123 	tmp.st_dev = huge_encode_dev(stat->dev);
124 	tmp.__pad1 = 0;
125 	tmp.__st_ino = stat->ino;
126 	tmp.st_mode = stat->mode;
127 	tmp.st_nlink = stat->nlink;
128 	tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
129 	tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
130 	tmp.st_rdev = huge_encode_dev(stat->rdev);
131 	tmp.st_size = stat->size;
132 	tmp.st_blocks = stat->blocks;
133 	tmp.__pad2 = 0;
134 	tmp.st_blksize = stat->blksize;
135 	tmp.st_atime = stat->atime.tv_sec;
136 	tmp.st_atime_nsec = stat->atime.tv_nsec;
137 	tmp.st_mtime = stat->mtime.tv_sec;
138 	tmp.st_mtime_nsec = stat->mtime.tv_nsec;
139 	tmp.st_ctime = stat->ctime.tv_sec;
140 	tmp.st_ctime_nsec = stat->ctime.tv_nsec;
141 	tmp.st_ino = stat->ino;
142 	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
143 }
144 
145 asmlinkage long sys_oabi_stat64(const char __user * filename,
146 				struct oldabi_stat64 __user * statbuf)
147 {
148 	struct kstat stat;
149 	int error = vfs_stat(filename, &stat);
150 	if (!error)
151 		error = cp_oldabi_stat64(&stat, statbuf);
152 	return error;
153 }
154 
155 asmlinkage long sys_oabi_lstat64(const char __user * filename,
156 				 struct oldabi_stat64 __user * statbuf)
157 {
158 	struct kstat stat;
159 	int error = vfs_lstat(filename, &stat);
160 	if (!error)
161 		error = cp_oldabi_stat64(&stat, statbuf);
162 	return error;
163 }
164 
165 asmlinkage long sys_oabi_fstat64(unsigned long fd,
166 				 struct oldabi_stat64 __user * statbuf)
167 {
168 	struct kstat stat;
169 	int error = vfs_fstat(fd, &stat);
170 	if (!error)
171 		error = cp_oldabi_stat64(&stat, statbuf);
172 	return error;
173 }
174 
175 asmlinkage long sys_oabi_fstatat64(int dfd,
176 				   const char __user *filename,
177 				   struct oldabi_stat64  __user *statbuf,
178 				   int flag)
179 {
180 	struct kstat stat;
181 	int error;
182 
183 	error = vfs_fstatat(dfd, filename, &stat, flag);
184 	if (error)
185 		return error;
186 	return cp_oldabi_stat64(&stat, statbuf);
187 }
188 
189 struct oabi_flock64 {
190 	short	l_type;
191 	short	l_whence;
192 	loff_t	l_start;
193 	loff_t	l_len;
194 	pid_t	l_pid;
195 } __attribute__ ((packed,aligned(4)));
196 
197 static long do_locks(unsigned int fd, unsigned int cmd,
198 				 unsigned long arg)
199 {
200 	struct flock64 kernel;
201 	struct oabi_flock64 user;
202 	mm_segment_t fs;
203 	long ret;
204 
205 	if (copy_from_user(&user, (struct oabi_flock64 __user *)arg,
206 			   sizeof(user)))
207 		return -EFAULT;
208 	kernel.l_type	= user.l_type;
209 	kernel.l_whence	= user.l_whence;
210 	kernel.l_start	= user.l_start;
211 	kernel.l_len	= user.l_len;
212 	kernel.l_pid	= user.l_pid;
213 
214 	fs = get_fs();
215 	set_fs(KERNEL_DS);
216 	ret = sys_fcntl64(fd, cmd, (unsigned long)&kernel);
217 	set_fs(fs);
218 
219 	if (!ret && (cmd == F_GETLK64 || cmd == F_OFD_GETLK)) {
220 		user.l_type	= kernel.l_type;
221 		user.l_whence	= kernel.l_whence;
222 		user.l_start	= kernel.l_start;
223 		user.l_len	= kernel.l_len;
224 		user.l_pid	= kernel.l_pid;
225 		if (copy_to_user((struct oabi_flock64 __user *)arg,
226 				 &user, sizeof(user)))
227 			ret = -EFAULT;
228 	}
229 	return ret;
230 }
231 
232 asmlinkage long sys_oabi_fcntl64(unsigned int fd, unsigned int cmd,
233 				 unsigned long arg)
234 {
235 	switch (cmd) {
236 	case F_OFD_GETLK:
237 	case F_OFD_SETLK:
238 	case F_OFD_SETLKW:
239 	case F_GETLK64:
240 	case F_SETLK64:
241 	case F_SETLKW64:
242 		return do_locks(fd, cmd, arg);
243 
244 	default:
245 		return sys_fcntl64(fd, cmd, arg);
246 	}
247 }
248 
249 struct oabi_epoll_event {
250 	__u32 events;
251 	__u64 data;
252 } __attribute__ ((packed,aligned(4)));
253 
254 asmlinkage long sys_oabi_epoll_ctl(int epfd, int op, int fd,
255 				   struct oabi_epoll_event __user *event)
256 {
257 	struct oabi_epoll_event user;
258 	struct epoll_event kernel;
259 	mm_segment_t fs;
260 	long ret;
261 
262 	if (op == EPOLL_CTL_DEL)
263 		return sys_epoll_ctl(epfd, op, fd, NULL);
264 	if (copy_from_user(&user, event, sizeof(user)))
265 		return -EFAULT;
266 	kernel.events = user.events;
267 	kernel.data   = user.data;
268 	fs = get_fs();
269 	set_fs(KERNEL_DS);
270 	ret = sys_epoll_ctl(epfd, op, fd, &kernel);
271 	set_fs(fs);
272 	return ret;
273 }
274 
275 asmlinkage long sys_oabi_epoll_wait(int epfd,
276 				    struct oabi_epoll_event __user *events,
277 				    int maxevents, int timeout)
278 {
279 	struct epoll_event *kbuf;
280 	mm_segment_t fs;
281 	long ret, err, i;
282 
283 	if (maxevents <= 0 ||
284 			maxevents > (INT_MAX/sizeof(*kbuf)) ||
285 			maxevents > (INT_MAX/sizeof(*events)))
286 		return -EINVAL;
287 	if (!access_ok(VERIFY_WRITE, events, sizeof(*events) * maxevents))
288 		return -EFAULT;
289 	kbuf = kmalloc_array(maxevents, sizeof(*kbuf), GFP_KERNEL);
290 	if (!kbuf)
291 		return -ENOMEM;
292 	fs = get_fs();
293 	set_fs(KERNEL_DS);
294 	ret = sys_epoll_wait(epfd, kbuf, maxevents, timeout);
295 	set_fs(fs);
296 	err = 0;
297 	for (i = 0; i < ret; i++) {
298 		__put_user_error(kbuf[i].events, &events->events, err);
299 		__put_user_error(kbuf[i].data,   &events->data,   err);
300 		events++;
301 	}
302 	kfree(kbuf);
303 	return err ? -EFAULT : ret;
304 }
305 
306 struct oabi_sembuf {
307 	unsigned short	sem_num;
308 	short		sem_op;
309 	short		sem_flg;
310 	unsigned short	__pad;
311 };
312 
313 asmlinkage long sys_oabi_semtimedop(int semid,
314 				    struct oabi_sembuf __user *tsops,
315 				    unsigned nsops,
316 				    const struct timespec __user *timeout)
317 {
318 	struct sembuf *sops;
319 	struct timespec local_timeout;
320 	long err;
321 	int i;
322 
323 	if (nsops < 1 || nsops > SEMOPM)
324 		return -EINVAL;
325 	if (!access_ok(VERIFY_READ, tsops, sizeof(*tsops) * nsops))
326 		return -EFAULT;
327 	sops = kmalloc_array(nsops, sizeof(*sops), GFP_KERNEL);
328 	if (!sops)
329 		return -ENOMEM;
330 	err = 0;
331 	for (i = 0; i < nsops; i++) {
332 		__get_user_error(sops[i].sem_num, &tsops->sem_num, err);
333 		__get_user_error(sops[i].sem_op,  &tsops->sem_op,  err);
334 		__get_user_error(sops[i].sem_flg, &tsops->sem_flg, err);
335 		tsops++;
336 	}
337 	if (timeout) {
338 		/* copy this as well before changing domain protection */
339 		err |= copy_from_user(&local_timeout, timeout, sizeof(*timeout));
340 		timeout = &local_timeout;
341 	}
342 	if (err) {
343 		err = -EFAULT;
344 	} else {
345 		mm_segment_t fs = get_fs();
346 		set_fs(KERNEL_DS);
347 		err = sys_semtimedop(semid, sops, nsops, timeout);
348 		set_fs(fs);
349 	}
350 	kfree(sops);
351 	return err;
352 }
353 
354 asmlinkage long sys_oabi_semop(int semid, struct oabi_sembuf __user *tsops,
355 			       unsigned nsops)
356 {
357 	return sys_oabi_semtimedop(semid, tsops, nsops, NULL);
358 }
359 
360 asmlinkage int sys_oabi_ipc(uint call, int first, int second, int third,
361 			    void __user *ptr, long fifth)
362 {
363 	switch (call & 0xffff) {
364 	case SEMOP:
365 		return  sys_oabi_semtimedop(first,
366 					    (struct oabi_sembuf __user *)ptr,
367 					    second, NULL);
368 	case SEMTIMEDOP:
369 		return  sys_oabi_semtimedop(first,
370 					    (struct oabi_sembuf __user *)ptr,
371 					    second,
372 					    (const struct timespec __user *)fifth);
373 	default:
374 		return sys_ipc(call, first, second, third, ptr, fifth);
375 	}
376 }
377 
378 asmlinkage long sys_oabi_bind(int fd, struct sockaddr __user *addr, int addrlen)
379 {
380 	sa_family_t sa_family;
381 	if (addrlen == 112 &&
382 	    get_user(sa_family, &addr->sa_family) == 0 &&
383 	    sa_family == AF_UNIX)
384 			addrlen = 110;
385 	return sys_bind(fd, addr, addrlen);
386 }
387 
388 asmlinkage long sys_oabi_connect(int fd, struct sockaddr __user *addr, int addrlen)
389 {
390 	sa_family_t sa_family;
391 	if (addrlen == 112 &&
392 	    get_user(sa_family, &addr->sa_family) == 0 &&
393 	    sa_family == AF_UNIX)
394 			addrlen = 110;
395 	return sys_connect(fd, addr, addrlen);
396 }
397 
398 asmlinkage long sys_oabi_sendto(int fd, void __user *buff,
399 				size_t len, unsigned flags,
400 				struct sockaddr __user *addr,
401 				int addrlen)
402 {
403 	sa_family_t sa_family;
404 	if (addrlen == 112 &&
405 	    get_user(sa_family, &addr->sa_family) == 0 &&
406 	    sa_family == AF_UNIX)
407 			addrlen = 110;
408 	return sys_sendto(fd, buff, len, flags, addr, addrlen);
409 }
410 
411 asmlinkage long sys_oabi_sendmsg(int fd, struct user_msghdr __user *msg, unsigned flags)
412 {
413 	struct sockaddr __user *addr;
414 	int msg_namelen;
415 	sa_family_t sa_family;
416 	if (msg &&
417 	    get_user(msg_namelen, &msg->msg_namelen) == 0 &&
418 	    msg_namelen == 112 &&
419 	    get_user(addr, &msg->msg_name) == 0 &&
420 	    get_user(sa_family, &addr->sa_family) == 0 &&
421 	    sa_family == AF_UNIX)
422 	{
423 		/*
424 		 * HACK ALERT: there is a limit to how much backward bending
425 		 * we should do for what is actually a transitional
426 		 * compatibility layer.  This already has known flaws with
427 		 * a few ioctls that we don't intend to fix.  Therefore
428 		 * consider this blatent hack as another one... and take care
429 		 * to run for cover.  In most cases it will "just work fine".
430 		 * If it doesn't, well, tough.
431 		 */
432 		put_user(110, &msg->msg_namelen);
433 	}
434 	return sys_sendmsg(fd, msg, flags);
435 }
436 
437 asmlinkage long sys_oabi_socketcall(int call, unsigned long __user *args)
438 {
439 	unsigned long r = -EFAULT, a[6];
440 
441 	switch (call) {
442 	case SYS_BIND:
443 		if (copy_from_user(a, args, 3 * sizeof(long)) == 0)
444 			r = sys_oabi_bind(a[0], (struct sockaddr __user *)a[1], a[2]);
445 		break;
446 	case SYS_CONNECT:
447 		if (copy_from_user(a, args, 3 * sizeof(long)) == 0)
448 			r = sys_oabi_connect(a[0], (struct sockaddr __user *)a[1], a[2]);
449 		break;
450 	case SYS_SENDTO:
451 		if (copy_from_user(a, args, 6 * sizeof(long)) == 0)
452 			r = sys_oabi_sendto(a[0], (void __user *)a[1], a[2], a[3],
453 					    (struct sockaddr __user *)a[4], a[5]);
454 		break;
455 	case SYS_SENDMSG:
456 		if (copy_from_user(a, args, 3 * sizeof(long)) == 0)
457 			r = sys_oabi_sendmsg(a[0], (struct user_msghdr __user *)a[1], a[2]);
458 		break;
459 	default:
460 		r = sys_socketcall(call, args);
461 	}
462 
463 	return r;
464 }
465