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/*
* lib/netfilter/nfnl.c Netfilter Netlink
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation version 2.1
* of the License.
*
* Copyright (c) 2003-2008 Thomas Graf <tgraf@suug.ch>
* Copyright (c) 2007 Philip Craig <philipc@snapgear.com>
* Copyright (c) 2007 Secure Computing Corporation
*/
/**
* @defgroup nfnl Netfilter Netlink
*
* @par Message Format
* @code
* <------- NLMSG_ALIGN(hlen) ------> <---- NLMSG_ALIGN(len) --->
* +----------------------------+- - -+- - - - - - - - - - -+- - -+
* | Header | Pad | Payload | Pad |
* | struct nlmsghdr | | | |
* +----------------------------+- - -+- - - - - - - - - - -+- - -+
* @endcode
* @code
* <-------- NFNL_HDRLEN --------->
* +--------------------------+- - -+------------+
* | Netfilter Netlink Header | Pad | Attributes |
* | struct nfgenmsg | | |
* +--------------------------+- - -+------------+
* nfnlmsg_attrdata(nfg, hdrlen)-----^
* @endcode
*
* @par 1) Creating a new netfilter netlink message
* @code
* struct nl_msg *msg;
*
* // Create a new empty netlink message
* msg = nlmsg_alloc();
*
* // Append the netlink and netfilter netlink message header
* hdr = nfnlmsg_put(msg, PID, SEQ, SUBSYS, TYPE, NLM_F_ECHO,
* FAMILY, RES_ID);
*
* // Append the attributes.
* nla_put_u32(msg, 1, 0x10);
*
* // Message is ready to be sent.
* nl_send_auto_complete(sk, msg);
*
* // All done? Free the message.
* nlmsg_free(msg);
* @endcode
*
* @par 2) Sending of trivial messages
* @code
* // For trivial messages not requiring any subsys specific header or
* // attributes, nfnl_send_simple() may be used to send messages directly.
* nfnl_send_simple(sk, SUBSYS, TYPE, 0, FAMILY, RES_ID);
* @endcode
* @{
*/
#include <netlink-local.h>
#include <netlink/netlink.h>
#include <netlink/netfilter/nfnl.h>
/**
* @name Socket Creating
* @{
*/
/**
* Create and connect netfilter netlink socket.
* @arg sk Netlink socket.
*
* Creates a NETLINK_NETFILTER netlink socket, binds the socket and
* issues a connection attempt.
*
* @see nl_connect()
*
* @return 0 on success or a negative error code.
*/
int nfnl_connect(struct nl_sock *sk)
{
return nl_connect(sk, NETLINK_NETFILTER);
}
/** @} */
/**
* @name Sending
* @{
*/
/**
* Send trivial netfilter netlink message
* @arg sk Netlink socket.
* @arg subsys_id nfnetlink subsystem
* @arg type nfnetlink message type
* @arg flags message flags
* @arg family nfnetlink address family
* @arg res_id nfnetlink resource id
*
* @return Newly allocated netlink message or NULL.
*/
int nfnl_send_simple(struct nl_sock *sk, uint8_t subsys_id, uint8_t type,
int flags, uint8_t family, uint16_t res_id)
{
struct nfgenmsg hdr = {
.nfgen_family = family,
.version = NFNETLINK_V0,
.res_id = htons(res_id),
};
return nl_send_simple(sk, NFNLMSG_TYPE(subsys_id, type), flags,
&hdr, sizeof(hdr));
}
/** @} */
/**
* @name Message Parsing
* @{
*/
/**
* Get netfilter subsystem id from message
* @arg nlh netlink messsage header
*/
uint8_t nfnlmsg_subsys(struct nlmsghdr *nlh)
{
return NFNL_SUBSYS_ID(nlh->nlmsg_type);
}
/**
* Get netfilter message type from message
* @arg nlh netlink messsage header
*/
uint8_t nfnlmsg_subtype(struct nlmsghdr *nlh)
{
return NFNL_MSG_TYPE(nlh->nlmsg_type);
}
/**
* Get netfilter family from message
* @arg nlh netlink messsage header
*/
uint8_t nfnlmsg_family(struct nlmsghdr *nlh)
{
struct nfgenmsg *nfg = nlmsg_data(nlh);
return nfg->nfgen_family;
}
/**
* Get netfilter resource id from message
* @arg nlh netlink messsage header
*/
uint16_t nfnlmsg_res_id(struct nlmsghdr *nlh)
{
struct nfgenmsg *nfg = nlmsg_data(nlh);
return ntohs(nfg->res_id);
}
/** @} */
/**
* @name Message Building
* @{
*/
static int nfnlmsg_append(struct nl_msg *msg, uint8_t family, uint16_t res_id)
{
struct nfgenmsg *nfg;
nfg = nlmsg_reserve(msg, sizeof(*nfg), NLMSG_ALIGNTO);
if (nfg == NULL)
return -NLE_NOMEM;
nfg->nfgen_family = family;
nfg->version = NFNETLINK_V0;
nfg->res_id = htons(res_id);
NL_DBG(2, "msg %p: Added nfnetlink header family=%d res_id=%d\n",
msg, family, res_id);
return 0;
}
/**
* Allocate a new netfilter netlink message
* @arg subsys_id nfnetlink subsystem
* @arg type nfnetlink message type
* @arg flags message flags
* @arg family nfnetlink address family
* @arg res_id nfnetlink resource id
*
* @return Newly allocated netlink message or NULL.
*/
struct nl_msg *nfnlmsg_alloc_simple(uint8_t subsys_id, uint8_t type, int flags,
uint8_t family, uint16_t res_id)
{
struct nl_msg *msg;
msg = nlmsg_alloc_simple(NFNLMSG_TYPE(subsys_id, type), flags);
if (msg == NULL)
return NULL;
if (nfnlmsg_append(msg, family, res_id) < 0)
goto nla_put_failure;
return msg;
nla_put_failure:
nlmsg_free(msg);
return NULL;
}
/**
* Add netlink and netfilter netlink headers to netlink message
* @arg msg netlink message
* @arg pid netlink process id
* @arg seq sequence number of message
* @arg subsys_id nfnetlink subsystem
* @arg type nfnetlink message type
* @arg flags message flags
* @arg family nfnetlink address family
* @arg res_id nfnetlink resource id
*/
int nfnlmsg_put(struct nl_msg *msg, uint32_t pid, uint32_t seq,
uint8_t subsys_id, uint8_t type, int flags, uint8_t family,
uint16_t res_id)
{
struct nlmsghdr *nlh;
nlh = nlmsg_put(msg, pid, seq, NFNLMSG_TYPE(subsys_id, type), 0, flags);
if (nlh == NULL)
return -NLE_MSGSIZE;
return nfnlmsg_append(msg, family, res_id);
}
/** @} */
/** @} */
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