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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>
This commit is contained in:
Paul Moore 2007-02-28 15:14:20 -05:00 committed by James Morris
parent de46c33745
commit f998e8cb52
1 changed files with 29 additions and 8 deletions
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37
net/ipv4/cipso_ipv4.c
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@ -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