audit: restore AUDIT_LOGINUID unset ABI

commit 041d7b98ffe59c59fdd639931dea7d74f9aa9a59 upstream.

A regression was caused by commit 780a7654cee8:
	 audit: Make testing for a valid loginuid explicit.
(which in turn attempted to fix a regression caused by e1760bd)

When audit_krule_to_data() fills in the rules to get a listing, there was a
missing clause to convert back from AUDIT_LOGINUID_SET to AUDIT_LOGINUID.

This broke userspace by not returning the same information that was sent and
expected.

The rule:
	auditctl -a exit,never -F auid=-1
gives:
	auditctl -l
		LIST_RULES: exit,never f24=0 syscall=all
when it should give:
		LIST_RULES: exit,never auid=-1 (0xffffffff) syscall=all

Tag it so that it is reported the same way it was set.  Create a new
private flags audit_krule field (pflags) to store it that won't interact with
the public one from the API.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 4fb28b23a4a4..c25cb64db967 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -46,6 +46,7 @@ struct audit_tree;
 
 struct audit_krule {
 	int			vers_ops;
+	u32			pflags;
 	u32			flags;
 	u32			listnr;
 	u32			action;
@@ -63,6 +64,9 @@ struct audit_krule {
 	u64			prio;
 };
 
+/* Flag to indicate legacy AUDIT_LOGINUID unset usage */
+#define AUDIT_LOGINUID_LEGACY		0x1
+
 struct audit_field {
 	u32				type;
 	u32				val;