[NETFITLER]: Add nfnetlink layer.

Introduce "nfnetlink" (netfilter netlink) layer.  This layer is used as
transport layer for all userspace communication of the new upcoming
netfilter subsystems, such as ctnetlink, nfnetlink_queue and some day even
the mythical pkttables ;)

Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Harald Welte 2005-08-09 19:30:24 -07:00 committed by David S. Miller
parent ac3247baf8
commit f9e815b376
6 changed files with 497 additions and 0 deletions

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@ -0,0 +1,145 @@
#ifndef _NFNETLINK_H
#define _NFNETLINK_H
#include <linux/types.h>
/* nfnetlink groups: Up to 32 maximum */
#define NF_NETLINK_CONNTRACK_NEW 0x00000001
#define NF_NETLINK_CONNTRACK_UPDATE 0x00000002
#define NF_NETLINK_CONNTRACK_DESTROY 0x00000004
#define NF_NETLINK_CONNTRACK_EXP_NEW 0x00000008
#define NF_NETLINK_CONNTRACK_EXP_UPDATE 0x00000010
#define NF_NETLINK_CONNTRACK_EXP_DESTROY 0x00000020
/* Generic structure for encapsulation optional netfilter information.
* It is reminiscent of sockaddr, but with sa_family replaced
* with attribute type.
* ! This should someday be put somewhere generic as now rtnetlink and
* ! nfnetlink use the same attributes methods. - J. Schulist.
*/
struct nfattr
{
u_int16_t nfa_len;
u_int16_t nfa_type;
} __attribute__ ((packed));
/* FIXME: Shamelessly copy and pasted from rtnetlink.h, it's time
* to put this in a generic file */
#define NFA_ALIGNTO 4
#define NFA_ALIGN(len) (((len) + NFA_ALIGNTO - 1) & ~(NFA_ALIGNTO - 1))
#define NFA_OK(nfa,len) ((len) > 0 && (nfa)->nfa_len >= sizeof(struct nfattr) \
&& (nfa)->nfa_len <= (len))
#define NFA_NEXT(nfa,attrlen) ((attrlen) -= NFA_ALIGN((nfa)->nfa_len), \
(struct nfattr *)(((char *)(nfa)) + NFA_ALIGN((nfa)->nfa_len)))
#define NFA_LENGTH(len) (NFA_ALIGN(sizeof(struct nfattr)) + (len))
#define NFA_SPACE(len) NFA_ALIGN(NFA_LENGTH(len))
#define NFA_DATA(nfa) ((void *)(((char *)(nfa)) + NFA_LENGTH(0)))
#define NFA_PAYLOAD(nfa) ((int)((nfa)->nfa_len) - NFA_LENGTH(0))
#define NFA_NEST(skb, type) \
({ struct nfattr *__start = (struct nfattr *) (skb)->tail; \
NFA_PUT(skb, type, 0, NULL); \
__start; })
#define NFA_NEST_END(skb, start) \
({ (start)->nfa_len = ((skb)->tail - (unsigned char *) (start)); \
(skb)->len; })
#define NFA_NEST_CANCEL(skb, start) \
({ if (start) \
skb_trim(skb, (unsigned char *) (start) - (skb)->data); \
-1; })
/* General form of address family dependent message.
*/
struct nfgenmsg {
u_int8_t nfgen_family; /* AF_xxx */
u_int8_t version; /* nfnetlink version */
u_int16_t res_id; /* resource id */
} __attribute__ ((packed));
#define NFNETLINK_V1 1
#define NFM_NFA(n) ((struct nfattr *)(((char *)(n)) \
+ NLMSG_ALIGN(sizeof(struct nfgenmsg))))
#define NFM_PAYLOAD(n) NLMSG_PAYLOAD(n, sizeof(struct nfgenmsg))
/* netfilter netlink message types are split in two pieces:
* 8 bit subsystem, 8bit operation.
*/
#define NFNL_SUBSYS_ID(x) ((x & 0xff00) >> 8)
#define NFNL_MSG_TYPE(x) (x & 0x00ff)
enum nfnl_subsys_id {
NFNL_SUBSYS_NONE = 0,
NFNL_SUBSYS_CTNETLINK,
NFNL_SUBSYS_CTNETLINK_EXP,
NFNL_SUBSYS_IPTNETLINK,
NFNL_SUBSYS_QUEUE,
NFNL_SUBSYS_ULOG,
NFNL_SUBSYS_COUNT,
};
#ifdef __KERNEL__
#include <linux/capability.h>
struct nfnl_callback
{
kernel_cap_t cap_required; /* capabilities required for this msg */
int (*call)(struct sock *nl, struct sk_buff *skb,
struct nlmsghdr *nlh, struct nfattr *cda[], int *errp);
};
struct nfnetlink_subsystem
{
const char *name;
__u8 subsys_id; /* nfnetlink subsystem ID */
__u8 cb_count; /* number of callbacks */
u_int32_t attr_count; /* number of nfattr's */
struct nfnl_callback *cb; /* callback for individual types */
};
extern void __nfa_fill(struct sk_buff *skb, int attrtype,
int attrlen, const void *data);
#define NFA_PUT(skb, attrtype, attrlen, data) \
({ if (skb_tailroom(skb) < (int)NFA_SPACE(attrlen)) goto nfattr_failure; \
__nfa_fill(skb, attrtype, attrlen, data); })
extern struct semaphore nfnl_sem;
#define nfnl_shlock() down(&nfnl_sem)
#define nfnl_shlock_nowait() down_trylock(&nfnl_sem)
#define nfnl_shunlock() do { up(&nfnl_sem); \
if(nfnl && nfnl->sk_receive_queue.qlen) \
nfnl->sk_data_ready(nfnl, 0); \
} while(0)
extern void nfnl_lock(void);
extern void nfnl_unlock(void);
extern int nfnetlink_subsys_register(struct nfnetlink_subsystem *n);
extern int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n);
extern int nfattr_parse(struct nfattr *tb[], int maxattr,
struct nfattr *nfa, int len);
#define nfattr_parse_nested(tb, max, nfa) \
nfattr_parse((tb), (max), NFA_DATA((nfa)), NFA_PAYLOAD((nfa)))
#define nfattr_bad_size(tb, max, cta_min) \
({ int __i, __res = 0; \
for (__i=0; __i<max; __i++) \
if (tb[__i] && NFA_PAYLOAD(tb[__i]) < cta_min[__i]){ \
__res = 1; \
break; \
} \
__res; \
})
extern int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group,
int echo);
extern int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags);
#endif /* __KERNEL__ */
#endif /* _NFNETLINK_H */

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@ -205,6 +205,8 @@ config NET_PKTGEN
To compile this code as a module, choose M here: the
module will be called pktgen.
source "net/netfilter/Kconfig"
endmenu
endmenu

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@ -16,6 +16,7 @@ obj-$(CONFIG_NET) += $(tmp-y)
obj-$(CONFIG_LLC) += llc/
obj-$(CONFIG_NET) += ethernet/ 802/ sched/ netlink/
obj-$(CONFIG_INET) += ipv4/
obj-$(CONFIG_NETFILTER) += netfilter/
obj-$(CONFIG_XFRM) += xfrm/
obj-$(CONFIG_UNIX) += unix/
ifneq ($(CONFIG_IPV6),)

5
net/netfilter/Kconfig Normal file
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@ -0,0 +1,5 @@
config NETFILTER_NETLINK
tristate "Netfilter netlink interface"
help
If this option is enabled, the kernel will include support
for the new netfilter netlink interface.

1
net/netfilter/Makefile Normal file
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@ -0,0 +1 @@
obj-$(CONFIG_NETFILTER_NETLINK) += nfnetlink.o

343
net/netfilter/nfnetlink.c Normal file
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@ -0,0 +1,343 @@
/* Netfilter messages via netlink socket. Allows for user space
* protocol helpers and general trouble making from userspace.
*
* (C) 2001 by Jay Schulist <jschlst@samba.org>,
* (C) 2002-2005 by Harald Welte <laforge@gnumonks.org>
* (C) 2005 by Pablo Neira Ayuso <pablo@eurodev.net>
*
* Initial netfilter messages via netlink development funded and
* generally made possible by Network Robots, Inc. (www.networkrobots.com)
*
* Further development of this code funded by Astaro AG (http://www.astaro.com)
*
* This software may be used and distributed according to the terms
* of the GNU General Public License, incorporated herein by reference.
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/fcntl.h>
#include <linux/skbuff.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <net/sock.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/netfilter.h>
#include <linux/netlink.h>
#include <linux/netfilter/nfnetlink.h>
MODULE_LICENSE("GPL");
static char __initdata nfversion[] = "0.30";
#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif
static struct sock *nfnl = NULL;
static struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT];
DECLARE_MUTEX(nfnl_sem);
void nfnl_lock(void)
{
nfnl_shlock();
}
void nfnl_unlock(void)
{
nfnl_shunlock();
}
int nfnetlink_subsys_register(struct nfnetlink_subsystem *n)
{
DEBUGP("registering subsystem ID %u\n", n->subsys_id);
/* If the netlink socket wasn't created, then fail */
if (!nfnl)
return -1;
nfnl_lock();
subsys_table[n->subsys_id] = n;
nfnl_unlock();
return 0;
}
int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n)
{
DEBUGP("unregistering subsystem ID %u\n", n->subsys_id);
nfnl_lock();
subsys_table[n->subsys_id] = NULL;
nfnl_unlock();
return 0;
}
static inline struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type)
{
u_int8_t subsys_id = NFNL_SUBSYS_ID(type);
if (subsys_id >= NFNL_SUBSYS_COUNT
|| subsys_table[subsys_id] == NULL)
return NULL;
return subsys_table[subsys_id];
}
static inline struct nfnl_callback *
nfnetlink_find_client(u_int16_t type, struct nfnetlink_subsystem *ss)
{
u_int8_t cb_id = NFNL_MSG_TYPE(type);
if (cb_id >= ss->cb_count) {
DEBUGP("msgtype %u >= %u, returning\n", type, ss->cb_count);
return NULL;
}
return &ss->cb[cb_id];
}
void __nfa_fill(struct sk_buff *skb, int attrtype, int attrlen,
const void *data)
{
struct nfattr *nfa;
int size = NFA_LENGTH(attrlen);
nfa = (struct nfattr *)skb_put(skb, NFA_ALIGN(size));
nfa->nfa_type = attrtype;
nfa->nfa_len = size;
memcpy(NFA_DATA(nfa), data, attrlen);
}
int nfattr_parse(struct nfattr *tb[], int maxattr, struct nfattr *nfa, int len)
{
memset(tb, 0, sizeof(struct nfattr *) * maxattr);
while (NFA_OK(nfa, len)) {
unsigned flavor = nfa->nfa_type;
if (flavor && flavor <= maxattr)
tb[flavor-1] = nfa;
nfa = NFA_NEXT(nfa, len);
}
return 0;
}
/**
* nfnetlink_check_attributes - check and parse nfnetlink attributes
*
* subsys: nfnl subsystem for which this message is to be parsed
* nlmsghdr: netlink message to be checked/parsed
* cda: array of pointers, needs to be at least subsys->attr_count big
*
*/
static int
nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys,
struct nlmsghdr *nlh, struct nfattr *cda[])
{
int min_len;
memset(cda, 0, sizeof(struct nfattr *) * subsys->attr_count);
/* check attribute lengths. */
min_len = NLMSG_ALIGN(sizeof(struct nfgenmsg));
if (nlh->nlmsg_len < min_len)
return -EINVAL;
if (nlh->nlmsg_len > min_len) {
struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh));
int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
while (NFA_OK(attr, attrlen)) {
unsigned flavor = attr->nfa_type;
if (flavor) {
if (flavor > subsys->attr_count)
return -EINVAL;
cda[flavor - 1] = attr;
}
attr = NFA_NEXT(attr, attrlen);
}
} else
return -EINVAL;
return 0;
}
int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
{
int allocation = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL;
int err = 0;
NETLINK_CB(skb).dst_groups = group;
if (echo)
atomic_inc(&skb->users);
netlink_broadcast(nfnl, skb, pid, group, allocation);
if (echo)
err = netlink_unicast(nfnl, skb, pid, MSG_DONTWAIT);
return err;
}
int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags)
{
return netlink_unicast(nfnl, skb, pid, flags);
}
/* Process one complete nfnetlink message. */
static inline int nfnetlink_rcv_msg(struct sk_buff *skb,
struct nlmsghdr *nlh, int *errp)
{
struct nfnl_callback *nc;
struct nfnetlink_subsystem *ss;
int type, err = 0;
DEBUGP("entered; subsys=%u, msgtype=%u\n",
NFNL_SUBSYS_ID(nlh->nlmsg_type),
NFNL_MSG_TYPE(nlh->nlmsg_type));
/* Only requests are handled by kernel now. */
if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
DEBUGP("received non-request message\n");
return 0;
}
/* All the messages must at least contain nfgenmsg */
if (nlh->nlmsg_len <
NLMSG_LENGTH(NLMSG_ALIGN(sizeof(struct nfgenmsg)))) {
DEBUGP("received message was too short\n");
return 0;
}
type = nlh->nlmsg_type;
ss = nfnetlink_get_subsys(type);
if (!ss)
goto err_inval;
nc = nfnetlink_find_client(type, ss);
if (!nc) {
DEBUGP("unable to find client for type %d\n", type);
goto err_inval;
}
if (nc->cap_required &&
!cap_raised(NETLINK_CB(skb).eff_cap, nc->cap_required)) {
DEBUGP("permission denied for type %d\n", type);
*errp = -EPERM;
return -1;
}
{
struct nfattr *cda[ss->attr_count];
memset(cda, 0, ss->attr_count*sizeof(struct nfattr *));
err = nfnetlink_check_attributes(ss, nlh, cda);
if (err < 0)
goto err_inval;
err = nc->call(nfnl, skb, nlh, cda, errp);
*errp = err;
return err;
}
err_inval:
*errp = -EINVAL;
return -1;
}
/* Process one packet of messages. */
static inline int nfnetlink_rcv_skb(struct sk_buff *skb)
{
int err;
struct nlmsghdr *nlh;
while (skb->len >= NLMSG_SPACE(0)) {
u32 rlen;
nlh = (struct nlmsghdr *)skb->data;
if (nlh->nlmsg_len < sizeof(struct nlmsghdr)
|| skb->len < nlh->nlmsg_len)
return 0;
rlen = NLMSG_ALIGN(nlh->nlmsg_len);
if (rlen > skb->len)
rlen = skb->len;
if (nfnetlink_rcv_msg(skb, nlh, &err)) {
if (!err)
return -1;
netlink_ack(skb, nlh, err);
} else
if (nlh->nlmsg_flags & NLM_F_ACK)
netlink_ack(skb, nlh, 0);
skb_pull(skb, rlen);
}
return 0;
}
static void nfnetlink_rcv(struct sock *sk, int len)
{
do {
struct sk_buff *skb;
if (nfnl_shlock_nowait())
return;
while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
if (nfnetlink_rcv_skb(skb)) {
if (skb->len)
skb_queue_head(&sk->sk_receive_queue,
skb);
else
kfree_skb(skb);
break;
}
kfree_skb(skb);
}
up(&nfnl_sem);
} while(nfnl && nfnl->sk_receive_queue.qlen);
}
void __exit nfnetlink_exit(void)
{
printk("Removing netfilter NETLINK layer.\n");
sock_release(nfnl->sk_socket);
return;
}
int __init nfnetlink_init(void)
{
printk("Netfilter messages via NETLINK v%s.\n", nfversion);
nfnl = netlink_kernel_create(NETLINK_NETFILTER, nfnetlink_rcv);
if (!nfnl) {
printk(KERN_ERR "cannot initialize nfnetlink!\n");
return -1;
}
return 0;
}
module_init(nfnetlink_init);
module_exit(nfnetlink_exit);
EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
EXPORT_SYMBOL_GPL(nfnetlink_send);
EXPORT_SYMBOL_GPL(nfnetlink_unicast);
EXPORT_SYMBOL_GPL(nfattr_parse);
EXPORT_SYMBOL_GPL(__nfa_fill);