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Commit f998e8cb authored by Paul Moore's avatar Paul Moore Committed by James Morris
Browse files

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: default avatarPaul Moore <paul.moore@hp.com>
Signed-off-by: default avatarJames Morris <jmorris@namei.org>
parent de46c337

net/ipv4/cipso_ipv4.c

+29 −8
Original line number Diff line number Diff line
@@ -91,6 +91,33 @@ static struct cipso_v4_map_cache_bkt *cipso_v4_cache = NULL; 
int cipso_v4_rbm_optfmt = 0;

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 @@ static int cipso_v4_map_cat_rng_hton(const struct cipso_v4_doi *doi_def, 
				     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 @@ static int cipso_v4_map_cat_rng_ntoh(const struct cipso_v4_doi *doi_def, 
 * 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