From 1bdbdfdf12ae35f08f5dcbec06a35c8d0f11ef55 Mon Sep 17 00:00:00 2001
From: Jonathan Bauer
Date: Fri, 29 May 2020 14:37:49 +0200
Subject: Initial working state

* Moved old Makefile to Kbuild.in
* New Makefile to compile against running kernel (or KDIR)
* Moved file format defines from loop/include/uapi/linux/loop.h to loop_file_fmt.h
* Moved definitions of loop_info{,64} to loop_file_fmt.h
* Renamed loop_info{,64} to xloop_info{,64}
* Removed checks for file format support which was now unneeded
---
 Kbuild.in       |  11 ++++++
 Makefile        |  15 +++----
 README.md       |  15 +++++++
 loop_file_fmt.h |   6 +++
 loop_main.c     | 120 +++++++++++++++-----------------------------------------
 loop_main.h     |  35 ++++++++++++++++-
 6 files changed, 106 insertions(+), 96 deletions(-)
 create mode 100644 Kbuild.in
 create mode 100644 README.md

diff --git a/Kbuild.in b/Kbuild.in
new file mode 100644
index 0000000..c50333a
--- /dev/null
+++ b/Kbuild.in
@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: GPL-2.0
+
+loop-y                                   += loop_main.o loop_file_fmt.o
+obj-$(CONFIG_BLK_DEV_LOOP)               += loop.o
+
+obj-$(CONFIG_BLK_DEV_CRYPTOLOOP)         += cryptoloop.o
+
+obj-$(CONFIG_BLK_DEV_LOOP_FILE_FMT_RAW)  += loop_file_fmt_raw.o
+
+loop_file_fmt_qcow-y                     += loop_file_fmt_qcow_main.o loop_file_fmt_qcow_cluster.o loop_file_fmt_qcow_cache.o
+obj-$(CONFIG_BLK_DEV_LOOP_FILE_FMT_QCOW) += loop_file_fmt_qcow.o
diff --git a/Makefile b/Makefile
index a82cd7a..b7f2191 100644
--- a/Makefile
+++ b/Makefile
@@ -1,11 +1,12 @@
 # SPDX-License-Identifier: GPL-2.0
+include $(PWD)/Kbuild.in
 
-loop-y						             += loop_main.o loop_file_fmt.o
-obj-$(CONFIG_BLK_DEV_LOOP)	             += loop.o
+ifndef KDIR
+	KDIR = /lib/modules/$(shell uname -r)/build
+endif
 
-obj-$(CONFIG_BLK_DEV_CRYPTOLOOP)         += cryptoloop.o
+all:
+	make -C "$(KDIR)" "M=$(PWD)" modules
 
-obj-$(CONFIG_BLK_DEV_LOOP_FILE_FMT_RAW)  += loop_file_fmt_raw.o
-
-loop_file_fmt_qcow-y                     += loop_file_fmt_qcow_main.o loop_file_fmt_qcow_cluster.o loop_file_fmt_qcow_cache.o
-obj-$(CONFIG_BLK_DEV_LOOP_FILE_FMT_QCOW) += loop_file_fmt_qcow.o
+clean:
+	make -C "$(KDIR)" "M=$(PWD)" clean
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..e32b858
--- /dev/null
+++ b/README.md
@@ -0,0 +1,15 @@
+Building the modules:
+
+```shell
+$ make CONFIG_BLK_DEV_LOOP_FILE_FMT_QCOW=m CONFIG_BLK_DEV_LOOP_FILE_FMT_RAW=m
+```
+
+Results in:
+* xloop.ko
+* loop_file_fmt_raw.ko
+* loop_file_fmt_qcow.ko
+
+Clean:
+```shell
+$ make clean
+```
diff --git a/loop_file_fmt.h b/loop_file_fmt.h
index 5c0e493..8a16c86 100644
--- a/loop_file_fmt.h
+++ b/loop_file_fmt.h
@@ -14,6 +14,12 @@
 
 struct loop_file_fmt;
 
+#define LO_FILE_FMT_RAW         0
+#define LO_FILE_FMT_QCOW        1
+#define LO_FILE_FMT_VDI         2
+#define LO_FILE_FMT_VMDK        3
+#define MAX_LO_FILE_FMT         (LO_FILE_FMT_VMDK + 1)
+
 /**
  * struct loop_file_fmt_ops - File format subsystem operations
  *
diff --git a/loop_main.c b/loop_main.c
index 7c1bb19..3bf4f1f 100644
--- a/loop_main.c
+++ b/loop_main.c
@@ -121,7 +121,7 @@ static int transfer_xor(struct loop_device *lo, int cmd,
 	return 0;
 }
 
-static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
+static int xor_init(struct loop_device *lo, const struct xloop_info64 *info)
 {
 	if (unlikely(info->lo_encrypt_key_size <= 0))
 		return -EINVAL;
@@ -741,7 +741,7 @@ loop_release_xfer(struct loop_device *lo)
 
 static int
 loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
-	       const struct loop_info64 *i)
+	       const struct xloop_info64 *i)
 {
 	int err = 0;
 
@@ -906,7 +906,7 @@ static int loop_clr_fd(struct loop_device *lo)
 }
 
 static int
-loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
+loop_set_status(struct loop_device *lo, const struct xloop_info64 *info)
 {
 	int err;
 	struct loop_func_table *xfer;
@@ -1043,7 +1043,7 @@ out_unlock:
 }
 
 static int
-loop_get_status(struct loop_device *lo, struct loop_info64 *info)
+loop_get_status(struct loop_device *lo, struct xloop_info64 *info)
 {
 	struct path path;
 	struct kstat stat;
@@ -1088,7 +1088,7 @@ loop_get_status(struct loop_device *lo, struct loop_info64 *info)
 }
 
 static void
-loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
+loop_info64_from_old(const struct xloop_info *info, struct xloop_info64 *info64)
 {
 	memset(info64, 0, sizeof(*info64));
 	info64->lo_number = info->lo_number;
@@ -1111,7 +1111,7 @@ loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
 }
 
 static int
-loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
+loop_info64_to_old(const struct xloop_info64 *info64, struct xloop_info *info)
 {
 	memset(info, 0, sizeof(*info));
 	info->lo_number = info64->lo_number;
@@ -1142,61 +1142,39 @@ loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
 }
 
 static int
-loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
+loop_set_status_old(struct loop_device *lo, const struct xloop_info __user *arg)
 {
-	struct loop_info info;
-	struct loop_info64 info64;
+	struct xloop_info info;
+	struct xloop_info64 info64;
 	int err;
 
-	/* backward compatibility: copy everything except the file format type
-	 * field */
-	err = copy_from_user(&info, arg,
-		sizeof(info) - sizeof(info.lo_file_fmt_type));
+	/* copy everything from the user space */
+	err = copy_from_user(&info, arg, sizeof(info));
 	if (err)
 		return -EFAULT;
 
-	if (info.lo_flags & LO_FLAGS_FILE_FMT) {
-		/* copy everything from the user space */
-		err = copy_from_user(&info, arg, sizeof(info));
-		if (err)
-			return -EFAULT;
-	} else {
-		info64.lo_file_fmt_type = LO_FILE_FMT_RAW;
-	}
-
 	loop_info64_from_old(&info, &info64);
 	return loop_set_status(lo, &info64);
 }
 
 static int
-loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
+loop_set_status64(struct loop_device *lo, const struct xloop_info64 __user *arg)
 {
-	struct loop_info64 info64;
+	struct xloop_info64 info64;
 	int err;
 
-	/* backward compatibility: copy everything except the file format type
-	 * field */
-	err = copy_from_user(&info64, arg,
-		sizeof(info64) - sizeof(info64.lo_file_fmt_type));
+	/* copy everything from the user space */
+	err = copy_from_user(&info64, arg, sizeof(info64));
 	if (err)
 		return -EFAULT;
 
-	if (info64.lo_flags & LO_FLAGS_FILE_FMT) {
-		/* copy everything from the user space */
-		err = copy_from_user(&info64, arg, sizeof(info64));
-		if (err)
-			return -EFAULT;
-	} else {
-		info64.lo_file_fmt_type = LO_FILE_FMT_RAW;
-	}
-
 	return loop_set_status(lo, &info64);
 }
 
 static int
-loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
-	struct loop_info info;
-	struct loop_info64 info64;
+loop_get_status_old(struct loop_device *lo, struct xloop_info __user *arg) {
+	struct xloop_info info;
+	struct xloop_info64 info64;
 	int lo_flags;
 	int err;
 
@@ -1216,15 +1194,7 @@ loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
 	if (!err)
 		err = loop_info64_to_old(&info64, &info);
 
-	if (lo_flags & LO_FLAGS_FILE_FMT) {
-		/* copy entire structure to user space because file format
-		 * support is available */
-		err = copy_to_user(arg, &info, sizeof(info));
-	} else {
-		/* copy normal structure to user space */
-		err = copy_to_user(arg, &info,
-			sizeof(info) - sizeof(info.lo_file_fmt_type));
-	}
+	err = copy_to_user(arg, &info, sizeof(info));
 
 	if (err)
 		return -EFAULT;
@@ -1233,8 +1203,8 @@ loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
 }
 
 static int
-loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
-	struct loop_info64 info64;
+loop_get_status64(struct loop_device *lo, struct xloop_info64 __user *arg) {
+	struct xloop_info64 info64;
 	u32 lo_flags;
 	int err;
 
@@ -1254,15 +1224,7 @@ loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
 	if (err)
 		return -EFAULT;
 
-	if (lo_flags & LO_FLAGS_FILE_FMT) {
-		/* copy entire structure to user space because file format
-		 * support is available */
-		err = copy_to_user(arg, &info64, sizeof(info64));
-	} else {
-		/* copy normal structure to user space */
-		err = copy_to_user(arg, &info64,
-			sizeof(info64) - sizeof(info64.lo_file_fmt_type));
-	}
+	err = copy_to_user(arg, &info64, sizeof(info64));
 
 	if (err)
 		return -EFAULT;
@@ -1371,20 +1333,20 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode,
 		err = -EPERM;
 		if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
 			err = loop_set_status_old(lo,
-					(struct loop_info __user *)arg);
+					(struct xloop_info __user *)arg);
 		}
 		break;
 	case LOOP_GET_STATUS:
-		return loop_get_status_old(lo, (struct loop_info __user *) arg);
+		return loop_get_status_old(lo, (struct xloop_info __user *) arg);
 	case LOOP_SET_STATUS64:
 		err = -EPERM;
 		if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
 			err = loop_set_status64(lo,
-					(struct loop_info64 __user *) arg);
+					(struct xloop_info64 __user *) arg);
 		}
 		break;
 	case LOOP_GET_STATUS64:
-		return loop_get_status64(lo, (struct loop_info64 __user *) arg);
+		return loop_get_status64(lo, (struct xloop_info64 __user *) arg);
 	case LOOP_SET_CAPACITY:
 	case LOOP_SET_DIRECT_IO:
 	case LOOP_SET_BLOCK_SIZE:
@@ -1422,27 +1384,17 @@ struct compat_loop_info {
  */
 static noinline int
 loop_info64_from_compat(const struct compat_loop_info __user *arg,
-			struct loop_info64 *info64)
+			struct xloop_info64 *info64)
 {
 	struct compat_loop_info info;
 	int err;
 
 	/* backward compatibility: copy everything except the file format type
 	 * field */
-	err = copy_from_user(&info, arg,
-		sizeof(info) - sizeof(info.lo_file_fmt_type));
+	err = copy_from_user(&info, arg, sizeof(info));
 	if (err)
 		return -EFAULT;
 
-	if (info.lo_flags & LO_FLAGS_FILE_FMT) {
-		/* copy everything from the user space */
-		err = copy_from_user(&info, arg, sizeof(info));
-		if (err)
-			return -EFAULT;
-	} else {
-		info.lo_file_fmt_type = LO_FILE_FMT_RAW;
-	}
-
 	memset(info64, 0, sizeof(*info64));
 	info64->lo_number = info.lo_number;
 	info64->lo_device = info.lo_device;
@@ -1469,7 +1421,7 @@ loop_info64_from_compat(const struct compat_loop_info __user *arg,
  * - noinlined to reduce stack space usage in main part of driver
  */
 static noinline int
-loop_info64_to_compat(const struct loop_info64 *info64,
+loop_info64_to_compat(const struct xloop_info64 *info64,
 		      struct compat_loop_info __user *arg)
 {
 	struct compat_loop_info info;
@@ -1513,15 +1465,7 @@ loop_info64_to_compat(const struct loop_info64 *info64,
 	    info.lo_file_fmt_type != info64->lo_file_fmt_type)
 		return -EOVERFLOW;
 
-	if (lo_flags & LO_FLAGS_FILE_FMT) {
-		/* copy entire structure to user space because file format
-		 * support is available */
-		err = copy_to_user(arg, &info, sizeof(info));
-	} else {
-		/* copy normal structure to user space */
-		err = copy_to_user(arg, &info,
-			sizeof(info) - sizeof(info.lo_file_fmt_type));
-	}
+	err = copy_to_user(arg, &info, sizeof(info));
 
 	if (err)
 		return -EFAULT;
@@ -1533,7 +1477,7 @@ static int
 loop_set_status_compat(struct loop_device *lo,
 		       const struct compat_loop_info __user *arg)
 {
-	struct loop_info64 info64;
+	struct xloop_info64 info64;
 	int ret;
 
 	ret = loop_info64_from_compat(arg, &info64);
@@ -1546,7 +1490,7 @@ static int
 loop_get_status_compat(struct loop_device *lo,
 		       struct compat_loop_info __user *arg)
 {
-	struct loop_info64 info64;
+	struct xloop_info64 info64;
 	int err;
 
 	if (!arg)
diff --git a/loop_main.h b/loop_main.h
index 33f6578..324ec2e 100644
--- a/loop_main.h
+++ b/loop_main.h
@@ -32,6 +32,39 @@ enum {
 
 struct loop_func_table;
 
+struct xloop_info {
+	int		   lo_number;		/* ioctl r/o */
+	__kernel_old_dev_t lo_device; 		/* ioctl r/o */
+	unsigned long	   lo_inode; 		/* ioctl r/o */
+	__kernel_old_dev_t lo_rdevice; 		/* ioctl r/o */
+	int		   lo_offset;
+	int		   lo_encrypt_type;
+	int		   lo_encrypt_key_size; 	/* ioctl w/o */
+	int		   lo_flags;			/* ioctl r/o */
+	char		   lo_name[LO_NAME_SIZE];
+	unsigned char	   lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
+	unsigned long	   lo_init[2];
+	char		   reserved[4];
+	int		   lo_file_fmt_type;
+};
+
+struct xloop_info64 {
+	__u64		   lo_device;			/* ioctl r/o */
+	__u64		   lo_inode;			/* ioctl r/o */
+	__u64		   lo_rdevice;			/* ioctl r/o */
+	__u64		   lo_offset;
+	__u64		   lo_sizelimit;/* bytes, 0 == max available */
+	__u32		   lo_number;			/* ioctl r/o */
+	__u32		   lo_encrypt_type;
+	__u32		   lo_encrypt_key_size;		/* ioctl w/o */
+	__u32		   lo_flags;			/* ioctl r/o */
+	__u8		   lo_file_name[LO_NAME_SIZE];
+	__u8		   lo_crypt_name[LO_NAME_SIZE];
+	__u8		   lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
+	__u64		   lo_init[2];
+	__u32		   lo_file_fmt_type;
+} __attribute__((packed));
+
 struct loop_device {
 	int		lo_number;
 	atomic_t	lo_refcnt;
@@ -93,7 +126,7 @@ struct loop_func_table {
 			struct page *raw_page, unsigned raw_off,
 			struct page *loop_page, unsigned loop_off,
 			int size, sector_t real_block);
-	int (*init)(struct loop_device *, const struct loop_info64 *); 
+	int (*init)(struct loop_device *, const struct xloop_info64 *);
 	/* release is called from loop_unregister_transfer or clr_fd */
 	int (*release)(struct loop_device *); 
 	int (*ioctl)(struct loop_device *, int cmd, unsigned long arg);
-- 
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