Network Packet Filter API

Network Packet Filter API. More...

Modules
	Basic Filter Conditions
	Ethernet Filter Conditions

Data Structures
struct	npf_test
	common filter test structure to be embedded into larger structures More...
struct	npf_rule
	filter rule structure More...
struct	npf_rule_list
	rule set for a given test location More...

Macros
#define	NPF_RULE(_name, _result, ...)
	Statically define one packet filter rule.

Functions
void	npf_insert_rule (struct npf_rule_list *rules, struct npf_rule *rule)
	Insert a rule at the front of given rule list.
void	npf_append_rule (struct npf_rule_list *rules, struct npf_rule *rule)
	Append a rule at the end of given rule list.
bool	npf_remove_rule (struct npf_rule_list *rules, struct npf_rule *rule)
	Remove a rule from the given rule list.
bool	npf_remove_all_rules (struct npf_rule_list *rules)
	Remove all rules from the given rule list.

Variables
struct npf_rule	npf_default_ok
	Default rule list termination for accepting a packet.
struct npf_rule	npf_default_drop
	Default rule list termination for rejecting a packet.
struct npf_rule_list	npf_send_rules
	rule list applied to outgoing packets
struct npf_rule_list	npf_recv_rules
	rule list applied to incoming packets
struct npf_rule_list	npf_local_in_recv_rules
	rule list applied for local incoming packets
struct npf_rule_list	npf_ipv4_recv_rules
	rule list applied for IPv4 incoming packets
struct npf_rule_list	npf_ipv6_recv_rules
	rule list applied for IPv6 incoming packets

Detailed Description

Network Packet Filter API.

Macro Definition Documentation

NPF_RULE

#define NPF_RULE	(		_name,
			_result,
			...
	)

#include <zephyr/net/net_pkt_filter.h>

Value:

        struct npf_rule _name = { \
                .result = (_result), \
                .nb_tests = NUM_VA_ARGS_LESS_1(__VA_ARGS__) + 1, \
                .tests = { FOR_EACH(Z_NPF_TEST_ADDR, (,), __VA_ARGS__) }, \
        }

Statically define one packet filter rule.

This creates a rule from a variable amount of filter conditions. This rule can then be inserted or appended to the rule list for a given network packet path.

Example:

static NPF_SIZE_MAX(maxsize_200, 200);
static NPF_ETH_TYPE_MATCH(ip_packet, NET_ETH_PTYPE_IP);
 
static NPF_RULE(small_ip_pkt, NET_OK, ip_packet, maxsize_200);
 
void install_my_filter(void)
{
    npf_insert_recv_rule(&npf_default_drop);
    npf_insert_recv_rule(&small_ip_pkt);
}

The above would accept IP packets that are 200 bytes or smaller, and drop all other packets.

Another (less efficient) way to create the same result could be:

static NPF_SIZE_MIN(minsize_201, 201);
static NPF_ETH_TYPE_UNMATCH(not_ip_packet, NET_ETH_PTYPE_IP);
 
static NPF_RULE(reject_big_pkts, NET_DROP, minsize_201);
static NPF_RULE(reject_non_ip, NET_DROP, not_ip_packet);
 
void install_my_filter(void) {
    npf_append_recv_rule(&reject_big_pkts);
    npf_append_recv_rule(&reject_non_ip);
    npf_append_recv_rule(&npf_default_ok);
}

The first rule in the list for which all conditions are true determines the fate of the packet. If one condition is false then the next rule in the list is evaluated.

Parameters

_name	Name for this rule.
_result	Fate of the packet if all conditions are true, either NET_OK or NET_DROP.
...	List of conditions for this rule.

Function Documentation

npf_append_rule()

void npf_append_rule	(	struct npf_rule_list *	rules,
		struct npf_rule *	rule
	)

#include <zephyr/net/net_pkt_filter.h>

Append a rule at the end of given rule list.

Parameters

rules	the affected rule list
rule	the rule to be appended

npf_insert_rule()

void npf_insert_rule	(	struct npf_rule_list *	rules,
		struct npf_rule *	rule
	)

#include <zephyr/net/net_pkt_filter.h>

Insert a rule at the front of given rule list.

Parameters

rules	the affected rule list
rule	the rule to be inserted

npf_remove_all_rules()

bool npf_remove_all_rules

(

struct npf_rule_list *

rules

)

#include <zephyr/net/net_pkt_filter.h>

Remove all rules from the given rule list.

Parameters

rules

the affected rule list

Return values

true	if at least one rule was removed from the rule list

npf_remove_rule()

bool npf_remove_rule	(	struct npf_rule_list *	rules,
		struct npf_rule *	rule
	)

#include <zephyr/net/net_pkt_filter.h>

Remove a rule from the given rule list.

Parameters

rules	the affected rule list
rule	the rule to be removed

Return values

true	if given rule was found in the rule list and removed

Variable Documentation

npf_default_drop

struct npf_rule npf_default_drop

extern

#include <zephyr/net/net_pkt_filter.h>

Default rule list termination for rejecting a packet.

npf_default_ok

struct npf_rule npf_default_ok

extern

#include <zephyr/net/net_pkt_filter.h>

Default rule list termination for accepting a packet.

npf_ipv4_recv_rules

struct npf_rule_list npf_ipv4_recv_rules

extern

#include <zephyr/net/net_pkt_filter.h>

rule list applied for IPv4 incoming packets

npf_ipv6_recv_rules

struct npf_rule_list npf_ipv6_recv_rules

extern

#include <zephyr/net/net_pkt_filter.h>

rule list applied for IPv6 incoming packets

npf_local_in_recv_rules

struct npf_rule_list npf_local_in_recv_rules

extern

#include <zephyr/net/net_pkt_filter.h>

rule list applied for local incoming packets

npf_recv_rules

struct npf_rule_list npf_recv_rules

extern

#include <zephyr/net/net_pkt_filter.h>

rule list applied to incoming packets

npf_send_rules

struct npf_rule_list npf_send_rules

extern

#include <zephyr/net/net_pkt_filter.h>

rule list applied to outgoing packets