Merge patch series "filesystems selftests cleanups and fanotify test"

Amir Goldstein <amir73il@gmail.com> says:

This adds a test for fanotify mount ns notifications inside userns [1].

While working on the test I ended up making lots of cleanups to reduce
build dependency on make headers_install.

These patches got rid of the dependency for my kvm setup for the
affected filesystems tests.

Building with TOOLS_INCLUDES dir was recommended by John Hubbard [2].

NOTE #1: these patches are based on a merge of vfs-6.16.mount
(changes wrappers.h) into v6.15-rc5 (changes mount-notify_test.c),
so if this cleanup is acceptable, we should probably setup a selftests
branch for 6.16, so that it can be used to test the fanotify patches.

NOTE #2: some of the defines in wrappers.h are left for overlayfs and
mount_setattr tests, which were not converted to use TOOLS_INCLUDES.
I did not want to mess with those tests.

* patches from https://lore.kernel.org/20250509133240.529330-1-amir73il@gmail.com:
  selftests/fs/mount-notify: add a test variant running inside userns
  selftests/filesystems: create setup_userns() helper
  selftests/filesystems: create get_unique_mnt_id() helper
  selftests/fs/mount-notify: build with tools include dir
  selftests/mount_settattr: remove duplicate syscall definitions
  selftests/pidfd: move syscall definitions into wrappers.h
  selftests/fs/statmount: build with tools include dir
  selftests/filesystems: move wrapper.h out of overlayfs subdir

Link: https://lore.kernel.org/20250509133240.529330-1-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

tools/include/uapi/linux/fanotify.h

@@ -0,0 +1,274 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_LINUX_FANOTIFY_H
+#define _UAPI_LINUX_FANOTIFY_H
+
+#include <linux/types.h>
+
+/* the following events that user-space can register for */
+#define FAN_ACCESS		0x00000001	/* File was accessed */
+#define FAN_MODIFY		0x00000002	/* File was modified */
+#define FAN_ATTRIB		0x00000004	/* Metadata changed */
+#define FAN_CLOSE_WRITE		0x00000008	/* Writable file closed */
+#define FAN_CLOSE_NOWRITE	0x00000010	/* Unwritable file closed */
+#define FAN_OPEN		0x00000020	/* File was opened */
+#define FAN_MOVED_FROM		0x00000040	/* File was moved from X */
+#define FAN_MOVED_TO		0x00000080	/* File was moved to Y */
+#define FAN_CREATE		0x00000100	/* Subfile was created */
+#define FAN_DELETE		0x00000200	/* Subfile was deleted */
+#define FAN_DELETE_SELF		0x00000400	/* Self was deleted */
+#define FAN_MOVE_SELF		0x00000800	/* Self was moved */
+#define FAN_OPEN_EXEC		0x00001000	/* File was opened for exec */
+
+#define FAN_Q_OVERFLOW		0x00004000	/* Event queued overflowed */
+#define FAN_FS_ERROR		0x00008000	/* Filesystem error */
+
+#define FAN_OPEN_PERM		0x00010000	/* File open in perm check */
+#define FAN_ACCESS_PERM		0x00020000	/* File accessed in perm check */
+#define FAN_OPEN_EXEC_PERM	0x00040000	/* File open/exec in perm check */
+/* #define FAN_DIR_MODIFY	0x00080000 */	/* Deprecated (reserved) */
+
+#define FAN_PRE_ACCESS		0x00100000	/* Pre-content access hook */
+#define FAN_MNT_ATTACH		0x01000000	/* Mount was attached */
+#define FAN_MNT_DETACH		0x02000000	/* Mount was detached */
+
+#define FAN_EVENT_ON_CHILD	0x08000000	/* Interested in child events */
+
+#define FAN_RENAME		0x10000000	/* File was renamed */
+
+#define FAN_ONDIR		0x40000000	/* Event occurred against dir */
+
+/* helper events */
+#define FAN_CLOSE		(FAN_CLOSE_WRITE | FAN_CLOSE_NOWRITE) /* close */
+#define FAN_MOVE		(FAN_MOVED_FROM | FAN_MOVED_TO) /* moves */
+
+/* flags used for fanotify_init() */
+#define FAN_CLOEXEC		0x00000001
+#define FAN_NONBLOCK		0x00000002
+
+/* These are NOT bitwise flags.  Both bits are used together.  */
+#define FAN_CLASS_NOTIF		0x00000000
+#define FAN_CLASS_CONTENT	0x00000004
+#define FAN_CLASS_PRE_CONTENT	0x00000008
+
+/* Deprecated - do not use this in programs and do not add new flags here! */
+#define FAN_ALL_CLASS_BITS	(FAN_CLASS_NOTIF | FAN_CLASS_CONTENT | \
+				 FAN_CLASS_PRE_CONTENT)
+
+#define FAN_UNLIMITED_QUEUE	0x00000010
+#define FAN_UNLIMITED_MARKS	0x00000020
+#define FAN_ENABLE_AUDIT	0x00000040
+
+/* Flags to determine fanotify event format */
+#define FAN_REPORT_PIDFD	0x00000080	/* Report pidfd for event->pid */
+#define FAN_REPORT_TID		0x00000100	/* event->pid is thread id */
+#define FAN_REPORT_FID		0x00000200	/* Report unique file id */
+#define FAN_REPORT_DIR_FID	0x00000400	/* Report unique directory id */
+#define FAN_REPORT_NAME		0x00000800	/* Report events with name */
+#define FAN_REPORT_TARGET_FID	0x00001000	/* Report dirent target id  */
+#define FAN_REPORT_FD_ERROR	0x00002000	/* event->fd can report error */
+#define FAN_REPORT_MNT		0x00004000	/* Report mount events */
+
+/* Convenience macro - FAN_REPORT_NAME requires FAN_REPORT_DIR_FID */
+#define FAN_REPORT_DFID_NAME	(FAN_REPORT_DIR_FID | FAN_REPORT_NAME)
+/* Convenience macro - FAN_REPORT_TARGET_FID requires all other FID flags */
+#define FAN_REPORT_DFID_NAME_TARGET (FAN_REPORT_DFID_NAME | \
+				     FAN_REPORT_FID | FAN_REPORT_TARGET_FID)
+
+/* Deprecated - do not use this in programs and do not add new flags here! */
+#define FAN_ALL_INIT_FLAGS	(FAN_CLOEXEC | FAN_NONBLOCK | \
+				 FAN_ALL_CLASS_BITS | FAN_UNLIMITED_QUEUE |\
+				 FAN_UNLIMITED_MARKS)
+
+/* flags used for fanotify_modify_mark() */
+#define FAN_MARK_ADD		0x00000001
+#define FAN_MARK_REMOVE		0x00000002
+#define FAN_MARK_DONT_FOLLOW	0x00000004
+#define FAN_MARK_ONLYDIR	0x00000008
+/* FAN_MARK_MOUNT is		0x00000010 */
+#define FAN_MARK_IGNORED_MASK	0x00000020
+#define FAN_MARK_IGNORED_SURV_MODIFY	0x00000040
+#define FAN_MARK_FLUSH		0x00000080
+/* FAN_MARK_FILESYSTEM is	0x00000100 */
+#define FAN_MARK_EVICTABLE	0x00000200
+/* This bit is mutually exclusive with FAN_MARK_IGNORED_MASK bit */
+#define FAN_MARK_IGNORE		0x00000400
+
+/* These are NOT bitwise flags.  Both bits can be used togther.  */
+#define FAN_MARK_INODE		0x00000000
+#define FAN_MARK_MOUNT		0x00000010
+#define FAN_MARK_FILESYSTEM	0x00000100
+#define FAN_MARK_MNTNS		0x00000110
+
+/*
+ * Convenience macro - FAN_MARK_IGNORE requires FAN_MARK_IGNORED_SURV_MODIFY
+ * for non-inode mark types.
+ */
+#define FAN_MARK_IGNORE_SURV	(FAN_MARK_IGNORE | FAN_MARK_IGNORED_SURV_MODIFY)
+
+/* Deprecated - do not use this in programs and do not add new flags here! */
+#define FAN_ALL_MARK_FLAGS	(FAN_MARK_ADD |\
+				 FAN_MARK_REMOVE |\
+				 FAN_MARK_DONT_FOLLOW |\
+				 FAN_MARK_ONLYDIR |\
+				 FAN_MARK_MOUNT |\
+				 FAN_MARK_IGNORED_MASK |\
+				 FAN_MARK_IGNORED_SURV_MODIFY |\
+				 FAN_MARK_FLUSH)
+
+/* Deprecated - do not use this in programs and do not add new flags here! */
+#define FAN_ALL_EVENTS (FAN_ACCESS |\
+			FAN_MODIFY |\
+			FAN_CLOSE |\
+			FAN_OPEN)
+
+/*
+ * All events which require a permission response from userspace
+ */
+/* Deprecated - do not use this in programs and do not add new flags here! */
+#define FAN_ALL_PERM_EVENTS (FAN_OPEN_PERM |\
+			     FAN_ACCESS_PERM)
+
+/* Deprecated - do not use this in programs and do not add new flags here! */
+#define FAN_ALL_OUTGOING_EVENTS	(FAN_ALL_EVENTS |\
+				 FAN_ALL_PERM_EVENTS |\
+				 FAN_Q_OVERFLOW)
+
+#define FANOTIFY_METADATA_VERSION	3
+
+struct fanotify_event_metadata {
+	__u32 event_len;
+	__u8 vers;
+	__u8 reserved;
+	__u16 metadata_len;
+	__aligned_u64 mask;
+	__s32 fd;
+	__s32 pid;
+};
+
+#define FAN_EVENT_INFO_TYPE_FID		1
+#define FAN_EVENT_INFO_TYPE_DFID_NAME	2
+#define FAN_EVENT_INFO_TYPE_DFID	3
+#define FAN_EVENT_INFO_TYPE_PIDFD	4
+#define FAN_EVENT_INFO_TYPE_ERROR	5
+#define FAN_EVENT_INFO_TYPE_RANGE	6
+#define FAN_EVENT_INFO_TYPE_MNT		7
+
+/* Special info types for FAN_RENAME */
+#define FAN_EVENT_INFO_TYPE_OLD_DFID_NAME	10
+/* Reserved for FAN_EVENT_INFO_TYPE_OLD_DFID	11 */
+#define FAN_EVENT_INFO_TYPE_NEW_DFID_NAME	12
+/* Reserved for FAN_EVENT_INFO_TYPE_NEW_DFID	13 */
+
+/* Variable length info record following event metadata */
+struct fanotify_event_info_header {
+	__u8 info_type;
+	__u8 pad;
+	__u16 len;
+};
+
+/*
+ * Unique file identifier info record.
+ * This structure is used for records of types FAN_EVENT_INFO_TYPE_FID,
+ * FAN_EVENT_INFO_TYPE_DFID and FAN_EVENT_INFO_TYPE_DFID_NAME.
+ * For FAN_EVENT_INFO_TYPE_DFID_NAME there is additionally a null terminated
+ * name immediately after the file handle.
+ */
+struct fanotify_event_info_fid {
+	struct fanotify_event_info_header hdr;
+	__kernel_fsid_t fsid;
+	/*
+	 * Following is an opaque struct file_handle that can be passed as
+	 * an argument to open_by_handle_at(2).
+	 */
+	unsigned char handle[];
+};
+
+/*
+ * This structure is used for info records of type FAN_EVENT_INFO_TYPE_PIDFD.
+ * It holds a pidfd for the pid that was responsible for generating an event.
+ */
+struct fanotify_event_info_pidfd {
+	struct fanotify_event_info_header hdr;
+	__s32 pidfd;
+};
+
+struct fanotify_event_info_error {
+	struct fanotify_event_info_header hdr;
+	__s32 error;
+	__u32 error_count;
+};
+
+struct fanotify_event_info_range {
+	struct fanotify_event_info_header hdr;
+	__u32 pad;
+	__u64 offset;
+	__u64 count;
+};
+
+struct fanotify_event_info_mnt {
+	struct fanotify_event_info_header hdr;
+	__u64 mnt_id;
+};
+
+/*
+ * User space may need to record additional information about its decision.
+ * The extra information type records what kind of information is included.
+ * The default is none. We also define an extra information buffer whose
+ * size is determined by the extra information type.
+ *
+ * If the information type is Audit Rule, then the information following
+ * is the rule number that triggered the user space decision that
+ * requires auditing.
+ */
+
+#define FAN_RESPONSE_INFO_NONE		0
+#define FAN_RESPONSE_INFO_AUDIT_RULE	1
+
+struct fanotify_response {
+	__s32 fd;
+	__u32 response;
+};
+
+struct fanotify_response_info_header {
+	__u8 type;
+	__u8 pad;
+	__u16 len;
+};
+
+struct fanotify_response_info_audit_rule {
+	struct fanotify_response_info_header hdr;
+	__u32 rule_number;
+	__u32 subj_trust;
+	__u32 obj_trust;
+};
+
+/* Legit userspace responses to a _PERM event */
+#define FAN_ALLOW	0x01
+#define FAN_DENY	0x02
+/* errno other than EPERM can specified in upper byte of deny response */
+#define FAN_ERRNO_BITS	8
+#define FAN_ERRNO_SHIFT (32 - FAN_ERRNO_BITS)
+#define FAN_ERRNO_MASK	((1 << FAN_ERRNO_BITS) - 1)
+#define FAN_DENY_ERRNO(err) \
+	(FAN_DENY | ((((__u32)(err)) & FAN_ERRNO_MASK) << FAN_ERRNO_SHIFT))
+
+#define FAN_AUDIT	0x10	/* Bitmask to create audit record for result */
+#define FAN_INFO	0x20	/* Bitmask to indicate additional information */
+
+/* No fd set in event */
+#define FAN_NOFD	-1
+#define FAN_NOPIDFD	FAN_NOFD
+#define FAN_EPIDFD	-2
+
+/* Helper functions to deal with fanotify_event_metadata buffers */
+#define FAN_EVENT_METADATA_LEN (sizeof(struct fanotify_event_metadata))
+
+#define FAN_EVENT_NEXT(meta, len) ((len) -= (meta)->event_len, \
+				   (struct fanotify_event_metadata*)(((char *)(meta)) + \
+				   (meta)->event_len))
+
+#define FAN_EVENT_OK(meta, len)	((long)(len) >= (long)FAN_EVENT_METADATA_LEN && \
+				(long)(meta)->event_len >= (long)FAN_EVENT_METADATA_LEN && \
+				(long)(meta)->event_len <= (long)(len))
+
+#endif /* _UAPI_LINUX_FANOTIFY_H */