fs/locks: pass kernel struct flock to fcntl_getlk/setlk

This will make it easier to implement a sane compat fcntl syscall.

[ jlayton: fix undeclared identifiers in 32-bit fcntl64 syscall handler ]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NJeff Layton <jlayton@redhat.com>

fs/fcntl.c

@@ -246,6 +246,8 @@ static int f_getowner_uids(struct file *filp, unsigned long arg)
 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
 		struct file *filp)
 {
+	void __user *argp = (void __user *)arg;
+	struct flock flock;
 	long err = -EINVAL;
 
 	switch (cmd) {
@@ -273,7 +275,11 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
 	case F_OFD_GETLK:
 #endif
 	case F_GETLK:
-		err = fcntl_getlk(filp, cmd, (struct flock __user *) arg);
+		if (copy_from_user(&flock, argp, sizeof(flock)))
+			return -EFAULT;
+		err = fcntl_getlk(filp, cmd, &flock);
+		if (!err && copy_to_user(argp, &flock, sizeof(flock)))
+			return -EFAULT;
 		break;
 #if BITS_PER_LONG != 32
 	/* 32-bit arches must use fcntl64() */
@@ -283,7 +289,9 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
 		/* Fallthrough */
 	case F_SETLK:
 	case F_SETLKW:
-		err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg);
+		if (copy_from_user(&flock, argp, sizeof(flock)))
+			return -EFAULT;
+		err = fcntl_setlk(fd, filp, cmd, &flock);
 		break;
 	case F_GETOWN:
 		/*
@@ -383,7 +391,9 @@ SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
 		unsigned long, arg)
 {	
+	void __user *argp = (void __user *)arg;
 	struct fd f = fdget_raw(fd);
+	struct flock64 flock;
 	long err = -EBADF;
 
 	if (!f.file)
@@ -401,14 +411,21 @@ SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
 	switch (cmd) {
 	case F_GETLK64:
 	case F_OFD_GETLK:
-		err = fcntl_getlk64(f.file, cmd, (struct flock64 __user *) arg);
+		err = -EFAULT;
+		if (copy_from_user(&flock, argp, sizeof(flock)))
+			break;
+		err = fcntl_getlk64(f.file, cmd, &flock);
+		if (!err && copy_to_user(argp, &flock, sizeof(flock)))
+			err = -EFAULT;
 		break;
 	case F_SETLK64:
 	case F_SETLKW64:
 	case F_OFD_SETLK:
 	case F_OFD_SETLKW:
-		err = fcntl_setlk64(fd, f.file, cmd,
-				(struct flock64 __user *) arg);
+		err = -EFAULT;
+		if (copy_from_user(&flock, argp, sizeof(flock)))
+			break;
+		err = fcntl_setlk64(fd, f.file, cmd, &flock);
 		break;
 	default:
 		err = do_fcntl(fd, cmd, arg, f.file);

fs/locks.c

@@ -2084,26 +2084,22 @@ static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
 /* Report the first existing lock that would conflict with l.
  * This implements the F_GETLK command of fcntl().
  */
-int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock __user *l)
+int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock *flock)
 {
 	struct file_lock file_lock;
-	struct flock flock;
 	int error;
 
-	error = -EFAULT;
-	if (copy_from_user(&flock, l, sizeof(flock)))
-		goto out;
 	error = -EINVAL;
-	if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
+	if (flock->l_type != F_RDLCK && flock->l_type != F_WRLCK)
 		goto out;
 
-	error = flock_to_posix_lock(filp, &file_lock, &flock);
+	error = flock_to_posix_lock(filp, &file_lock, flock);
 	if (error)
 		goto out;
 
 	if (cmd == F_OFD_GETLK) {
 		error = -EINVAL;
-		if (flock.l_pid != 0)
+		if (flock->l_pid != 0)
 			goto out;
 
 		cmd = F_GETLK;
@@ -2115,15 +2111,12 @@ int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock __user *l)
 	if (error)
 		goto out;
  
-	flock.l_type = file_lock.fl_type;
+	flock->l_type = file_lock.fl_type;
 	if (file_lock.fl_type != F_UNLCK) {
-		error = posix_lock_to_flock(&flock, &file_lock);
+		error = posix_lock_to_flock(flock, &file_lock);
 		if (error)
 			goto rel_priv;
 	}
-	error = -EFAULT;
-	if (!copy_to_user(l, &flock, sizeof(flock)))
-		error = 0;
 rel_priv:
 	locks_release_private(&file_lock);
 out:
@@ -2216,26 +2209,16 @@ check_fmode_for_setlk(struct file_lock *fl)
  * This implements both the F_SETLK and F_SETLKW commands of fcntl().
  */
 int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
-		struct flock __user *l)
+		struct flock *flock)
 {
 	struct file_lock *file_lock = locks_alloc_lock();
-	struct flock flock;
-	struct inode *inode;
+	struct inode *inode = locks_inode(filp);
 	struct file *f;
 	int error;
 
 	if (file_lock == NULL)
 		return -ENOLCK;
 
-	inode = locks_inode(filp);
-
-	/*
-	 * This might block, so we do it before checking the inode.
-	 */
-	error = -EFAULT;
-	if (copy_from_user(&flock, l, sizeof(flock)))
-		goto out;
-
 	/* Don't allow mandatory locks on files that may be memory mapped
 	 * and shared.
 	 */
@@ -2244,7 +2227,7 @@ int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
 		goto out;
 	}
 
-	error = flock_to_posix_lock(filp, file_lock, &flock);
+	error = flock_to_posix_lock(filp, file_lock, flock);
 	if (error)
 		goto out;
 
@@ -2259,7 +2242,7 @@ int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
 	switch (cmd) {
 	case F_OFD_SETLK:
 		error = -EINVAL;
-		if (flock.l_pid != 0)
+		if (flock->l_pid != 0)
 			goto out;
 
 		cmd = F_SETLK;
@@ -2268,7 +2251,7 @@ int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
 		break;
 	case F_OFD_SETLKW:
 		error = -EINVAL;
-		if (flock.l_pid != 0)
+		if (flock->l_pid != 0)
 			goto out;
 
 		cmd = F_SETLKW;
@@ -2313,26 +2296,22 @@ int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
 /* Report the first existing lock that would conflict with l.
  * This implements the F_GETLK command of fcntl().
  */
-int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 __user *l)
+int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 *flock)
 {
 	struct file_lock file_lock;
-	struct flock64 flock;
 	int error;
 
-	error = -EFAULT;
-	if (copy_from_user(&flock, l, sizeof(flock)))
-		goto out;
 	error = -EINVAL;
-	if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
+	if (flock->l_type != F_RDLCK && flock->l_type != F_WRLCK)
 		goto out;
 
-	error = flock64_to_posix_lock(filp, &file_lock, &flock);
+	error = flock64_to_posix_lock(filp, &file_lock, flock);
 	if (error)
 		goto out;
 
 	if (cmd == F_OFD_GETLK) {
 		error = -EINVAL;
-		if (flock.l_pid != 0)
+		if (flock->l_pid != 0)
 			goto out;
 
 		cmd = F_GETLK64;
@@ -2344,13 +2323,9 @@ int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 __user *l)
 	if (error)
 		goto out;
 
-	flock.l_type = file_lock.fl_type;
+	flock->l_type = file_lock.fl_type;
 	if (file_lock.fl_type != F_UNLCK)
-		posix_lock_to_flock64(&flock, &file_lock);
-
-	error = -EFAULT;
-	if (!copy_to_user(l, &flock, sizeof(flock)))
-		error = 0;
+		posix_lock_to_flock64(flock, &file_lock);
 
 	locks_release_private(&file_lock);
 out:
@@ -2361,26 +2336,16 @@ int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 __user *l)
  * This implements both the F_SETLK and F_SETLKW commands of fcntl().
  */
 int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
-		struct flock64 __user *l)
+		struct flock64 *flock)
 {
 	struct file_lock *file_lock = locks_alloc_lock();
-	struct flock64 flock;
-	struct inode *inode;
+	struct inode *inode = locks_inode(filp);
 	struct file *f;
 	int error;
 
 	if (file_lock == NULL)
 		return -ENOLCK;
 
-	/*
-	 * This might block, so we do it before checking the inode.
-	 */
-	error = -EFAULT;
-	if (copy_from_user(&flock, l, sizeof(flock)))
-		goto out;
-
-	inode = locks_inode(filp);
-
 	/* Don't allow mandatory locks on files that may be memory mapped
 	 * and shared.
 	 */
@@ -2389,7 +2354,7 @@ int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
 		goto out;
 	}
 
-	error = flock64_to_posix_lock(filp, file_lock, &flock);
+	error = flock64_to_posix_lock(filp, file_lock, flock);
 	if (error)
 		goto out;
 
@@ -2404,7 +2369,7 @@ int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
 	switch (cmd) {
 	case F_OFD_SETLK:
 		error = -EINVAL;
-		if (flock.l_pid != 0)
+		if (flock->l_pid != 0)
 			goto out;
 
 		cmd = F_SETLK64;
@@ -2413,7 +2378,7 @@ int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
 		break;
 	case F_OFD_SETLKW:
 		error = -EINVAL;
-		if (flock.l_pid != 0)
+		if (flock->l_pid != 0)
 			goto out;
 
 		cmd = F_SETLKW64;

include/linux/fs.h

@@ -1038,14 +1038,14 @@ static inline struct inode *locks_inode(const struct file *f)
 }
 
 #ifdef CONFIG_FILE_LOCKING
-extern int fcntl_getlk(struct file *, unsigned int, struct flock __user *);
+extern int fcntl_getlk(struct file *, unsigned int, struct flock *);
 extern int fcntl_setlk(unsigned int, struct file *, unsigned int,
-			struct flock __user *);
+			struct flock *);
 
 #if BITS_PER_LONG == 32
-extern int fcntl_getlk64(struct file *, unsigned int, struct flock64 __user *);
+extern int fcntl_getlk64(struct file *, unsigned int, struct flock64 *);
 extern int fcntl_setlk64(unsigned int, struct file *, unsigned int,
-			struct flock64 __user *);
+			struct flock64 *);
 #endif
 
 extern int fcntl_setlease(unsigned int fd, struct file *filp, long arg);