compat_ioctl: move sys_compat_ioctl() to ioctl.c

The rest of the fs/compat_ioctl.c file is no longer useful now,
so move the actual syscall as planned.

Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

fs/Makefile

@@ -37,7 +37,7 @@ obj-$(CONFIG_FS_DAX)		+= dax.o
 obj-$(CONFIG_FS_ENCRYPTION)	+= crypto/
 obj-$(CONFIG_FS_VERITY)		+= verity/
 obj-$(CONFIG_FILE_LOCKING)      += locks.o
-obj-$(CONFIG_COMPAT)		+= compat.o compat_ioctl.o
+obj-$(CONFIG_COMPAT)		+= compat.o
 obj-$(CONFIG_BINFMT_AOUT)	+= binfmt_aout.o
 obj-$(CONFIG_BINFMT_EM86)	+= binfmt_em86.o
 obj-$(CONFIG_BINFMT_MISC)	+= binfmt_misc.o

fs/ioctl.c

@@ -788,4 +788,94 @@ long compat_ptr_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	return file->f_op->unlocked_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
 }
 EXPORT_SYMBOL(compat_ptr_ioctl);
+
+COMPAT_SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd,
+		       compat_ulong_t, arg32)
+{
+	unsigned long arg = arg32;
+	struct fd f = fdget(fd);
+	int error = -EBADF;
+	if (!f.file)
+		goto out;
+
+	/* RED-PEN how should LSM module know it's handling 32bit? */
+	error = security_file_ioctl(f.file, cmd, arg);
+	if (error)
+		goto out_fput;
+
+	switch (cmd) {
+	/* these are never seen by ->ioctl(), no argument or int argument */
+	case FIOCLEX:
+	case FIONCLEX:
+	case FIFREEZE:
+	case FITHAW:
+	case FICLONE:
+		goto do_ioctl;
+	/* these are never seen by ->ioctl(), pointer argument */
+	case FIONBIO:
+	case FIOASYNC:
+	case FIOQSIZE:
+	case FS_IOC_FIEMAP:
+	case FIGETBSZ:
+	case FICLONERANGE:
+	case FIDEDUPERANGE:
+		goto found_handler;
+	/*
+	 * The next group is the stuff handled inside file_ioctl().
+	 * For regular files these never reach ->ioctl(); for
+	 * devices, sockets, etc. they do and one (FIONREAD) is
+	 * even accepted in some cases.  In all those cases
+	 * argument has the same type, so we can handle these
+	 * here, shunting them towards do_vfs_ioctl().
+	 * ->compat_ioctl() will never see any of those.
+	 */
+	/* pointer argument, never actually handled by ->ioctl() */
+	case FIBMAP:
+		goto found_handler;
+	/* handled by some ->ioctl(); always a pointer to int */
+	case FIONREAD:
+		goto found_handler;
+	/* these get messy on amd64 due to alignment differences */
+#if defined(CONFIG_X86_64)
+	case FS_IOC_RESVSP_32:
+	case FS_IOC_RESVSP64_32:
+		error = compat_ioctl_preallocate(f.file, 0, compat_ptr(arg));
+		goto out_fput;
+	case FS_IOC_UNRESVSP_32:
+	case FS_IOC_UNRESVSP64_32:
+		error = compat_ioctl_preallocate(f.file, FALLOC_FL_PUNCH_HOLE,
+				compat_ptr(arg));
+		goto out_fput;
+	case FS_IOC_ZERO_RANGE_32:
+		error = compat_ioctl_preallocate(f.file, FALLOC_FL_ZERO_RANGE,
+				compat_ptr(arg));
+		goto out_fput;
+#else
+	case FS_IOC_RESVSP:
+	case FS_IOC_RESVSP64:
+	case FS_IOC_UNRESVSP:
+	case FS_IOC_UNRESVSP64:
+	case FS_IOC_ZERO_RANGE:
+		goto found_handler;
+#endif
+
+	default:
+		if (f.file->f_op->compat_ioctl) {
+			error = f.file->f_op->compat_ioctl(f.file, cmd, arg);
+			if (error != -ENOIOCTLCMD)
+				goto out_fput;
+		}
+		error = -ENOTTY;
+		goto out_fput;
+	}
+
+ found_handler:
+	arg = (unsigned long)compat_ptr(arg);
+ do_ioctl:
+	error = do_vfs_ioctl(f.file, fd, cmd, arg);
+ out_fput:
+	fdput(f);
+ out:
+	return error;
+}
 #endif