tools/syz-declextract: extract file_operations descriptions

Extend the clang tool to locate file_operations variables and arrays
and dump open/read/write/mmap/ioctl callbacks for each.
It also tries to extract set of ioctl commands and argument types
for them in a simple best-effort way (for now). It just locates switch
in the ioctl callback and extracts each case as a command.

7 files changed, 223 insertions, 0 deletions

diff --git a/tools/syz-declextract/testdata/file_operations.c b/tools/syz-declextract/testdata/file_operations.c
new file mode 100644
index 000000000..04d548f98
--- /dev/null
+++ b/tools/syz-declextract/testdata/file_operations.c
@@ -0,0 +1,45 @@
+// Copyright 2024 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+#include "include/fs.h"
+#include "include/uapi/file_operations.h"
+
+static void foo_open() {}
+static void foo_read() {}
+static void foo_write() {}
+static void foo_mmap() {}
+
+static void foo_ioctl(unsigned int cmd) {
+	switch (cmd) {
+	case FOO_IOCTL1:
+	case FOO_IOCTL2:
+	case FOO_IOCTL3:
+	case FOO_IOCTL4:
+	case FOO_IOCTL5:
+	}
+}
+
+const struct file_operations foo = {
+	.open = foo_open,
+	.read = foo_read,
+	.write = foo_write,
+	.unlocked_ioctl = foo_ioctl,
+	.mmap = foo_mmap,
+};
+
+static void proc_open() {}
+static void proc_read() {}
+static void proc_write() {}
+static void proc_ioctl(unsigned int cmd) {}
+
+const struct file_operations proc_ops[] = {
+	{
+		.open = proc_open,
+		.read_iter = proc_read,
+		.write_iter = proc_write,
+	},
+	{
+		.open = proc_open,
+		.unlocked_ioctl = proc_ioctl,
+	},
+};
diff --git a/tools/syz-declextract/testdata/file_operations.c.info b/tools/syz-declextract/testdata/file_operations.c.info
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/tools/syz-declextract/testdata/file_operations.c.info
diff --git a/tools/syz-declextract/testdata/file_operations.c.json b/tools/syz-declextract/testdata/file_operations.c.json
new file mode 100644
index 000000000..e5ddad2b2
--- /dev/null
+++ b/tools/syz-declextract/testdata/file_operations.c.json
@@ -0,0 +1,118 @@
+{
+	"includes": [
+		"include/uapi/file_operations.h"
+	],
+	"structs": [
+		{
+			"name": "foo_ioctl_arg",
+			"byte_size": 8,
+			"fields": [
+				{
+					"name": "a",
+					"counted_by": -1,
+					"type": {
+						"int": {
+							"byte_size": 4,
+							"name": "int",
+							"base": "int"
+						}
+					}
+				},
+				{
+					"name": "b",
+					"counted_by": -1,
+					"type": {
+						"int": {
+							"byte_size": 4,
+							"name": "int",
+							"base": "int"
+						}
+					}
+				}
+			]
+		}
+	],
+	"file_ops": [
+		{
+			"name": "foo_file_operations",
+			"open": "foo_open",
+			"read": "foo_read",
+			"write": "foo_write",
+			"mmap": "foo_mmap",
+			"ioctl": "foo_ioctl",
+			"ioctl_cmds": [
+				{
+					"name": "FOO_IOCTL5",
+					"type": {
+						"ptr": {
+							"elem": {
+								"struct": "foo_ioctl_arg"
+							}
+						}
+					}
+				},
+				{
+					"name": "FOO_IOCTL4",
+					"type": {
+						"ptr": {
+							"elem": {
+								"struct": "foo_ioctl_arg"
+							}
+						}
+					}
+				},
+				{
+					"name": "FOO_IOCTL3",
+					"type": {
+						"ptr": {
+							"elem": {
+								"struct": "foo_ioctl_arg"
+							},
+							"is_const": true
+						}
+					}
+				},
+				{
+					"name": "FOO_IOCTL2",
+					"type": {
+						"ptr": {
+							"elem": {
+								"int": {
+									"byte_size": 4,
+									"name": "int",
+									"base": "int"
+								}
+							},
+							"is_const": true
+						}
+					}
+				},
+				{
+					"name": "FOO_IOCTL1",
+					"type": {
+						"int": {
+							"byte_size": 1,
+							"is_const": true
+						}
+					}
+				}
+			],
+			"source_file": "file_operations.c"
+		},
+		{
+			"name": "proc_ops_file_operations",
+			"open": "proc_open",
+			"read": "proc_read",
+			"write": "proc_write",
+			"mmap": "proc_open",
+			"source_file": "file_operations.c"
+		},
+		{
+			"name": "proc_ops_file_operations1",
+			"open": "proc_open",
+			"mmap": "proc_open",
+			"ioctl": "proc_ioctl",
+			"source_file": "file_operations.c"
+		}
+	]
+}
\ No newline at end of file
diff --git a/tools/syz-declextract/testdata/file_operations.c.txt b/tools/syz-declextract/testdata/file_operations.c.txt
new file mode 100644
index 000000000..f2fb3ed1c
--- /dev/null
+++ b/tools/syz-declextract/testdata/file_operations.c.txt
@@ -0,0 +1,10 @@
+# Code generated by syz-declextract. DO NOT EDIT.
+
+meta automatic
+
+type auto_todo intptr
+
+include <vdso/bits.h>
+include <linux/types.h>
+include <net/netlink.h>
+include <include/uapi/file_operations.h>
diff --git a/tools/syz-declextract/testdata/include/fs.h b/tools/syz-declextract/testdata/include/fs.h
new file mode 100644
index 000000000..a5c838595
--- /dev/null
+++ b/tools/syz-declextract/testdata/include/fs.h
@@ -0,0 +1,12 @@
+// Copyright 2024 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+struct file_operations {
+	void (*open)(void);
+	void (*read)(void);
+	void (*write)(void);
+	void (*read_iter)(void);
+	void (*write_iter)(void);
+	void (*unlocked_ioctl)(unsigned int);
+	void (*mmap)(void);
+};
diff --git a/tools/syz-declextract/testdata/include/uapi/file_operations.h b/tools/syz-declextract/testdata/include/uapi/file_operations.h
new file mode 100644
index 000000000..6a2a8d259
--- /dev/null
+++ b/tools/syz-declextract/testdata/include/uapi/file_operations.h
@@ -0,0 +1,14 @@
+// Copyright 2024 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+#include "ioctl.h"
+
+#define FOO_IOCTL1		_IO('c', 1)
+#define FOO_IOCTL2		_IOR('c', 2, int)
+#define FOO_IOCTL3		_IOR('c', 3, struct foo_ioctl_arg)
+#define FOO_IOCTL4		_IOW('c', 4, struct foo_ioctl_arg)
+#define FOO_IOCTL5		_IOWR('c', 5, struct foo_ioctl_arg)
+
+struct foo_ioctl_arg {
+	int a, b;
+};
diff --git a/tools/syz-declextract/testdata/include/uapi/ioctl.h b/tools/syz-declextract/testdata/include/uapi/ioctl.h
new file mode 100644
index 000000000..fae14a74e
--- /dev/null
+++ b/tools/syz-declextract/testdata/include/uapi/ioctl.h
@@ -0,0 +1,24 @@
+// Copyright 2024 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+#define _IOC_NONE	0U
+#define _IOC_WRITE	1U
+#define _IOC_READ	2U
+
+#define _IOC_NRBITS	8
+#define _IOC_TYPEBITS	8
+#define _IOC_SIZEBITS	14
+#define _IOC_DIRBITS	2
+
+#define _IOC_NRSHIFT	0
+#define _IOC_TYPESHIFT	(_IOC_NRSHIFT+_IOC_NRBITS)
+#define _IOC_SIZESHIFT	(_IOC_TYPESHIFT+_IOC_TYPEBITS)
+#define _IOC_DIRSHIFT	(_IOC_SIZESHIFT+_IOC_SIZEBITS)
+
+#define _IOC(dir, type, nr, size) (((dir)  << _IOC_DIRSHIFT) | ((type) << _IOC_TYPESHIFT) | \
+	 ((nr)   << _IOC_NRSHIFT) | ((size) << _IOC_SIZESHIFT))
+
+#define _IO(type, nr)		_IOC(_IOC_NONE, (type), (nr), 0)
+#define _IOR(type, nr, arg)	_IOC(_IOC_READ, (type), (nr), (sizeof(arg)))
+#define _IOW(type, nr, arg)	_IOC(_IOC_WRITE, (type), (nr), (sizeof(arg)))
+#define _IOWR(type, nr, arg)	_IOC(_IOC_READ|_IOC_WRITE, (type), (nr), (sizeof(arg)))