[PATCH] netlabel: handle sparse category maps in netlbl_catmap_getlong()

From: Paul Moore <paul@paul-moore.com>

In cases where the category bitmap is sparse enough that gaps exist
between netlbl_lsm_catmap structs, callers to netlbl_catmap_getlong()
could find themselves prematurely ending their search through the
category bitmap.  Further, the methods used to calculate the 'idx'
and 'off' values were incorrect for bitmaps this large.  This patch
changes the netlbl_catmap_getlong() behavior so that it always skips
over gaps and calculates the index and offset values correctly.

Signed-off-by: Paul Moore <paul@paul-moore.com>
---
 net/netlabel/netlabel_kapi.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/net/netlabel/netlabel_kapi.c b/net/netlabel/netlabel_kapi.c
index bd007a9..3c070f2 100644
--- a/net/netlabel/netlabel_kapi.c
+++ b/net/netlabel/netlabel_kapi.c

@@ -609,20 +609,19 @@ int netlbl_catmap_getlong(struct netlbl_lsm_catmap *catmap,
 		off = catmap->startbit;
 		*offset = off;
 	}
-	iter = _netlbl_catmap_getnode(&catmap, off, _CM_F_NONE, 0);
+	iter = _netlbl_catmap_getnode(&catmap, off, _CM_F_WALK, 0);
 	if (iter == NULL) {
 		*offset = (u32)-1;
 		return 0;
 	}
 
 	if (off < iter->startbit) {
-		off = iter->startbit;
-		*offset = off;
+		*offset = iter->startbit;
+		off = 0;
 	} else
 		off -= iter->startbit;
-
 	idx = off / NETLBL_CATMAP_MAPSIZE;
-	*bitmap = iter->bitmap[idx] >> (off % NETLBL_CATMAP_SIZE);
+	*bitmap = iter->bitmap[idx] >> (off % NETLBL_CATMAP_MAPSIZE);
 
 	return 0;
 }

On Mon, Jun 13, 2016 at 10:16 AM, Paul Moore [off-list ref] wrote:

From: Paul Moore <paul@paul-moore.com>

In cases where the category bitmap is sparse enough that gaps exist
between netlbl_lsm_catmap structs, callers to netlbl_catmap_getlong()
could find themselves prematurely ending their search through the
category bitmap.  Further, the methods used to calculate the 'idx'
and 'off' values were incorrect for bitmaps this large.  This patch
changes the netlbl_catmap_getlong() behavior so that it always skips
over gaps and calculates the index and offset values correctly.

Signed-off-by: Paul Moore <paul@paul-moore.com>
---
 net/netlabel/netlabel_kapi.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

Another relatively small fix that I've merged into selinux#next, if
anyone has any objections, let me know.

-- 
paul moore
security @ redhat