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freebsd-skq/sys/netpfil/ipfw/ip_fw_bpf.c
Gleb Smirnoff f355cb3e6f PFIL_MEMPTR for ipfw link level hook 
With new pfil(9) KPI it is possible to pass a void pointer with length
instead of mbuf pointer to a packet filter. Until this commit no filters
supported that, so pfil run through a shim function pfil_fake_mbuf().

Now the ipfw(4) hook named "default-link", that is instantiated when
net.link.ether.ipfw sysctl is on, supports processing pointer/length
packets natively.

- ip_fw_args now has union for either mbuf or void *, and if flags have
  non-zero length, then we use the void *.
- through ipfw_chk() we handle mem/mbuf cases differently.
- ether_header goes away from args. It is ipfw_chk() responsibility
  to do parsing of Ethernet header.
- ipfw_log() now uses different bpf APIs to log packets.

Although ipfw_chk() is now capable to process pointer/length packets,
this commit adds support for the link level hook only, see
ipfw_check_frame(). Potentially the IP processing hook ipfw_check_packet()
can be improved too, but that requires more changes since the hook
supports more complex actions: NAT, divert, etc.

Reviewed by:	ae
Differential Revision:	https://reviews.freebsd.org/D19357
2019-03-14 22:52:16 +00:00

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/*-
* Copyright (c) 2016 Yandex LLC
* Copyright (c) 2016 Andrey V. Elsukov <ae@FreeBSD.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/rmlock.h>
#include <sys/socket.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <net/if_pflog.h>
#include <net/if_var.h>
#include <net/if_clone.h>
#include <net/if_types.h>
#include <net/vnet.h>
#include <net/bpf.h>
#include <netinet/in.h>
#include <netinet/ip_fw.h>
#include <netinet/ip_var.h>
#include <netpfil/ipfw/ip_fw_private.h>
VNET_DEFINE_STATIC(struct ifnet *, log_if);
VNET_DEFINE_STATIC(struct ifnet *, pflog_if);
VNET_DEFINE_STATIC(struct if_clone *, ipfw_cloner);
VNET_DEFINE_STATIC(struct if_clone *, ipfwlog_cloner);
#define V_ipfw_cloner VNET(ipfw_cloner)
#define V_ipfwlog_cloner VNET(ipfwlog_cloner)
#define V_log_if VNET(log_if)
#define V_pflog_if VNET(pflog_if)
static struct rmlock log_if_lock;
#define LOGIF_LOCK_INIT(x) rm_init(&log_if_lock, "ipfw log_if lock")
#define LOGIF_LOCK_DESTROY(x) rm_destroy(&log_if_lock)
#define LOGIF_RLOCK_TRACKER struct rm_priotracker _log_tracker
#define LOGIF_RLOCK(x) rm_rlock(&log_if_lock, &_log_tracker)
#define LOGIF_RUNLOCK(x) rm_runlock(&log_if_lock, &_log_tracker)
#define LOGIF_WLOCK(x) rm_wlock(&log_if_lock)
#define LOGIF_WUNLOCK(x) rm_wunlock(&log_if_lock)
static const char ipfwname[] = "ipfw";
static const char ipfwlogname[] = "ipfwlog";
static int
ipfw_bpf_ioctl(struct ifnet *ifp, u_long cmd, caddr_t addr)
{
return (EINVAL);
}
static int
ipfw_bpf_output(struct ifnet *ifp, struct mbuf *m,
const struct sockaddr *dst, struct route *ro)
{
if (m != NULL)
FREE_PKT(m);
return (0);
}
static void
ipfw_clone_destroy(struct ifnet *ifp)
{
LOGIF_WLOCK();
if (ifp->if_hdrlen == ETHER_HDR_LEN)
V_log_if = NULL;
else
V_pflog_if = NULL;
LOGIF_WUNLOCK();
bpfdetach(ifp);
if_detach(ifp);
if_free(ifp);
}
static int
ipfw_clone_create(struct if_clone *ifc, int unit, caddr_t params)
{
struct ifnet *ifp;
ifp = if_alloc(IFT_PFLOG);
if (ifp == NULL)
return (ENOSPC);
if_initname(ifp, ipfwname, unit);
ifp->if_flags = IFF_UP | IFF_SIMPLEX | IFF_MULTICAST;
ifp->if_mtu = 65536;
ifp->if_ioctl = ipfw_bpf_ioctl;
ifp->if_output = ipfw_bpf_output;
ifp->if_hdrlen = ETHER_HDR_LEN;
if_attach(ifp);
bpfattach(ifp, DLT_EN10MB, ETHER_HDR_LEN);
LOGIF_WLOCK();
if (V_log_if != NULL) {
LOGIF_WUNLOCK();
bpfdetach(ifp);
if_detach(ifp);
if_free(ifp);
return (EEXIST);
}
V_log_if = ifp;
LOGIF_WUNLOCK();
return (0);
}
static int
ipfwlog_clone_create(struct if_clone *ifc, int unit, caddr_t params)
{
struct ifnet *ifp;
ifp = if_alloc(IFT_PFLOG);
if (ifp == NULL)
return (ENOSPC);
if_initname(ifp, ipfwlogname, unit);
ifp->if_flags = IFF_UP | IFF_SIMPLEX | IFF_MULTICAST;
ifp->if_mtu = 65536;
ifp->if_ioctl = ipfw_bpf_ioctl;
ifp->if_output = ipfw_bpf_output;
ifp->if_hdrlen = PFLOG_HDRLEN;
if_attach(ifp);
bpfattach(ifp, DLT_PFLOG, PFLOG_HDRLEN);
LOGIF_WLOCK();
if (V_pflog_if != NULL) {
LOGIF_WUNLOCK();
bpfdetach(ifp);
if_detach(ifp);
if_free(ifp);
return (EEXIST);
}
V_pflog_if = ifp;
LOGIF_WUNLOCK();
return (0);
}
void
ipfw_bpf_tap(u_char *pkt, u_int pktlen)
{
LOGIF_RLOCK_TRACKER;
LOGIF_RLOCK();
if (V_log_if != NULL)
BPF_TAP(V_log_if, pkt, pktlen);
LOGIF_RUNLOCK();
}
void
ipfw_bpf_mtap(struct mbuf *m)
{
LOGIF_RLOCK_TRACKER;
LOGIF_RLOCK();
if (V_log_if != NULL)
BPF_MTAP(V_log_if, m);
LOGIF_RUNLOCK();
}
void
ipfw_bpf_mtap2(void *data, u_int dlen, struct mbuf *m)
{
struct ifnet *logif;
LOGIF_RLOCK_TRACKER;
LOGIF_RLOCK();
switch (dlen) {
case (ETHER_HDR_LEN):
logif = V_log_if;
break;
case (PFLOG_HDRLEN):
logif = V_pflog_if;
break;
default:
#ifdef INVARIANTS
panic("%s: unsupported len %d", __func__, dlen);
#endif
logif = NULL;
}
if (logif != NULL)
BPF_MTAP2(logif, data, dlen, m);
LOGIF_RUNLOCK();
}
void
ipfw_bpf_init(int first)
{
if (first) {
LOGIF_LOCK_INIT();
V_log_if = NULL;
V_pflog_if = NULL;
}
V_ipfw_cloner = if_clone_simple(ipfwname, ipfw_clone_create,
ipfw_clone_destroy, 0);
V_ipfwlog_cloner = if_clone_simple(ipfwlogname, ipfwlog_clone_create,
ipfw_clone_destroy, 0);
}
void
ipfw_bpf_uninit(int last)
{
if_clone_detach(V_ipfw_cloner);
if_clone_detach(V_ipfwlog_cloner);
if (last)
LOGIF_LOCK_DESTROY();
}
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