fanotify: deprecate uapi FAN_ALL_* constants

We do not want to add new bits to the FAN_ALL_* uapi constants
because they have been exposed to userspace.  If there are programs
out there using these constants, those programs could break if
re-compiled with modified FAN_ALL_* constants and run on an old kernel.

We deprecate the uapi constants FAN_ALL_* and define new FANOTIFY_*
constants for internal use to replace them. New feature bits will be
added only to the new constants.

Cc: <linux-api@vger.kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

2 files changed, 56 insertions, 9 deletions

diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index a8c3fc54276d..4519b0988afe 100644
--- a/include/linux/fanotify.h
+++ b/include/linux/fanotify.h
@@ -7,4 +7,51 @@
 #define FAN_GROUP_FLAG(group, flag) \
 	((group)->fanotify_data.flags & (flag))
 
+/*
+ * Flags allowed to be passed from/to userspace.
+ *
+ * We intentionally do not add new bits to the old FAN_ALL_* constants, because
+ * they are uapi exposed constants. If there are programs out there using
+ * these constant, the programs may break if re-compiled with new uapi headers
+ * and then run on an old kernel.
+ */
+#define FANOTIFY_CLASS_BITS	(FAN_CLASS_NOTIF | FAN_CLASS_CONTENT | \
+				 FAN_CLASS_PRE_CONTENT)
+
+#define FANOTIFY_INIT_FLAGS	(FANOTIFY_CLASS_BITS | \
+				 FAN_CLOEXEC | FAN_NONBLOCK | \
+				 FAN_UNLIMITED_QUEUE | FAN_UNLIMITED_MARKS)
+
+#define FANOTIFY_MARK_TYPE_BITS	(FAN_MARK_INODE | FAN_MARK_MOUNT | \
+				 FAN_MARK_FILESYSTEM)
+
+#define FANOTIFY_MARK_FLAGS	(FANOTIFY_MARK_TYPE_BITS | \
+				 FAN_MARK_ADD | \
+				 FAN_MARK_REMOVE | \
+				 FAN_MARK_DONT_FOLLOW | \
+				 FAN_MARK_ONLYDIR | \
+				 FAN_MARK_IGNORED_MASK | \
+				 FAN_MARK_IGNORED_SURV_MODIFY | \
+				 FAN_MARK_FLUSH)
+
+/* Events that user can request to be notified on */
+#define FANOTIFY_EVENTS		(FAN_ACCESS | FAN_MODIFY | \
+				 FAN_CLOSE | FAN_OPEN)
+
+/* Events that require a permission response from user */
+#define FANOTIFY_PERM_EVENTS	(FAN_OPEN_PERM | FAN_ACCESS_PERM)
+
+/* Events that may be reported to user */
+#define FANOTIFY_OUTGOING_EVENTS	(FANOTIFY_EVENTS | \
+					 FANOTIFY_PERM_EVENTS | \
+					 FAN_Q_OVERFLOW)
+
+/* Do not use these old uapi constants internally */
+#undef FAN_ALL_CLASS_BITS
+#undef FAN_ALL_INIT_FLAGS
+#undef FAN_ALL_MARK_FLAGS
+#undef FAN_ALL_EVENTS
+#undef FAN_ALL_PERM_EVENTS
+#undef FAN_ALL_OUTGOING_EVENTS
+
 #endif /* _LINUX_FANOTIFY_H */
diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h
index ad81234d1919..d0c05de670ef 100644
--- a/include/uapi/linux/fanotify.h
+++ b/include/uapi/linux/fanotify.h
@@ -31,6 +31,8 @@
 #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)
 
@@ -38,6 +40,7 @@
 #define FAN_UNLIMITED_MARKS	0x00000020
 #define FAN_ENABLE_AUDIT	0x00000040
 
+/* 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)
@@ -57,23 +60,18 @@
 #define FAN_MARK_INODE		0x00000000
 #define FAN_MARK_MOUNT		0x00000010
 #define FAN_MARK_FILESYSTEM	0x00000100
-#define FAN_MARK_TYPE_MASK	(FAN_MARK_INODE | FAN_MARK_MOUNT | \
-				 FAN_MARK_FILESYSTEM)
 
+/* 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|\
-				 FAN_MARK_TYPE_MASK)
+				 FAN_MARK_FLUSH)
 
-/*
- * All of the events - we build the list by hand so that we can add flags in
- * the future and not break backward compatibility.  Apps will get only the
- * events that they originally wanted.  Be sure to add new events here!
- */
+/* Deprecated - do not use this in programs and do not add new flags here! */
 #define FAN_ALL_EVENTS (FAN_ACCESS |\
 			FAN_MODIFY |\
 			FAN_CLOSE |\
@@ -82,9 +80,11 @@
 /*
  * 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)