NetLabel: cleanup and document CIPSO constants
This patch collects all of the CIPSO constants and puts them in one place; it
also documents each value explaining how the value is derived.
Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 2ce5b69..d466bd5 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -92,6 +92,33 @@
int cipso_v4_rbm_strictvalid = 1;
/*
+ * Protocol Constants
+ */
+
+/* Maximum size of the CIPSO IP option, derived from the fact that the maximum
+ * IPv4 header size is 60 bytes and the base IPv4 header is 20 bytes long. */
+#define CIPSO_V4_OPT_LEN_MAX 40
+
+/* Length of the base CIPSO option, this includes the option type (1 byte), the
+ * option length (1 byte), and the DOI (4 bytes). */
+#define CIPSO_V4_HDR_LEN 6
+
+/* Base length of the restrictive category bitmap tag (tag #1). */
+#define CIPSO_V4_TAG_RBM_BLEN 4
+
+/* Base length of the enumerated category tag (tag #2). */
+#define CIPSO_V4_TAG_ENUM_BLEN 4
+
+/* Base length of the ranged categories bitmap tag (tag #5). */
+#define CIPSO_V4_TAG_RNG_BLEN 4
+/* The maximum number of category ranges permitted in the ranged category tag
+ * (tag #5). You may note that the IETF draft states that the maximum number
+ * of category ranges is 7, but if the low end of the last category range is
+ * zero then it is possibile to fit 8 category ranges because the zero should
+ * be omitted. */
+#define CIPSO_V4_TAG_RNG_CAT_MAX 8
+
+/*
* Helper Functions
*/
@@ -1109,15 +1136,12 @@
unsigned char *net_cat,
u32 net_cat_len)
{
- /* The constant '16' is not random, it is the maximum number of
- * high/low category range pairs as permitted by the CIPSO draft based
- * on a maximum IPv4 header length of 60 bytes - the BUG_ON() assertion
- * does a sanity check to make sure we don't overflow the array. */
int iter = -1;
- u16 array[16];
+ u16 array[CIPSO_V4_TAG_RNG_CAT_MAX * 2];
u32 array_cnt = 0;
u32 cat_size = 0;
+ /* make sure we don't overflow the 'array[]' variable */
BUG_ON(net_cat_len > 30);
for (;;) {
@@ -1196,9 +1220,6 @@
* Protocol Handling Functions
*/
-#define CIPSO_V4_OPT_LEN_MAX 40
-#define CIPSO_V4_HDR_LEN 6
-
/**
* cipso_v4_gentag_hdr - Generate a CIPSO option header
* @doi_def: the DOI definition