netlabel: Replace protocol/NetLabel linking with refrerence counts

NetLabel has always had a list of backpointers in the CIPSO DOI definition
structure which pointed to the NetLabel LSM domain mapping structures which
referenced the CIPSO DOI struct.  The rationale for this was that when an
administrator removed a CIPSO DOI from the system all of the associated
NetLabel LSM domain mappings should be removed as well; a list of
backpointers made this a simple operation.

Unfortunately, while the backpointers did make the removal easier they were
a bit of a mess from an implementation point of view which was making
further development difficult.  Since the removal of a CIPSO DOI is a
realtively rare event it seems to make sense to remove this backpointer
list as the optimization was hurting us more then it was helping.  However,
we still need to be able to track when a CIPSO DOI definition is being used
so replace the backpointer list with a reference count.  In order to
preserve the current functionality of removing the associated LSM domain
mappings when a CIPSO DOI is removed we walk the LSM domain mapping table,
removing the relevant entries.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Reviewed-by: James Morris <jmorris@namei.org>

1 files changed, 11 insertions, 10 deletions

diff --git a/include/net/cipso_ipv4.h b/include/net/cipso_ipv4.h
index a6bb945..5fe6556 100644
--- a/include/net/cipso_ipv4.h
+++ b/include/net/cipso_ipv4.h
@@ -40,6 +40,7 @@
 #include <linux/net.h>
 #include <linux/skbuff.h>
 #include <net/netlabel.h>
+#include <asm/atomic.h>
 
 /* known doi values */
 #define CIPSO_V4_DOI_UNKNOWN          0x00000000
@@ -79,10 +80,9 @@ struct cipso_v4_doi {
 	} map;
 	u8 tags[CIPSO_V4_TAG_MAXCNT];
 
-	u32 valid;
+	atomic_t refcount;
 	struct list_head list;
 	struct rcu_head rcu;
-	struct list_head dom_list;
 };
 
 /* Standard CIPSO mapping table */
@@ -128,25 +128,26 @@ extern int cipso_v4_rbm_strictvalid;
 
 #ifdef CONFIG_NETLABEL
 int cipso_v4_doi_add(struct cipso_v4_doi *doi_def);
-int cipso_v4_doi_remove(u32 doi,
-			struct netlbl_audit *audit_info,
-			void (*callback) (struct rcu_head * head));
+void cipso_v4_doi_free(struct cipso_v4_doi *doi_def);
+int cipso_v4_doi_remove(u32 doi, struct netlbl_audit *audit_info);
 struct cipso_v4_doi *cipso_v4_doi_getdef(u32 doi);
+void cipso_v4_doi_putdef(struct cipso_v4_doi *doi_def);
 int cipso_v4_doi_walk(u32 *skip_cnt,
 		     int (*callback) (struct cipso_v4_doi *doi_def, void *arg),
 	             void *cb_arg);
-int cipso_v4_doi_domhsh_add(struct cipso_v4_doi *doi_def, const char *domain);
-int cipso_v4_doi_domhsh_remove(struct cipso_v4_doi *doi_def,
-			       const char *domain);
 #else
 static inline int cipso_v4_doi_add(struct cipso_v4_doi *doi_def)
 {
 	return -ENOSYS;
 }
 
+static inline void cipso_v4_doi_free(struct cipso_v4_doi *doi_def)
+{
+	return;
+}
+
 static inline int cipso_v4_doi_remove(u32 doi,
-				    struct netlbl_audit *audit_info,
-				    void (*callback) (struct rcu_head * head))
+				      struct netlbl_audit *audit_info)
 {
 	return 0;
 }