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freebsd/sys/net/bpfdesc.h
Christian S.J. Peron 93e39f0b93 Introduce two new ioctl(2) commands, BIOCLOCK and BIOCSETWF. These commands
enhance the security of bpf(4) by further relinquishing the privilege of
the bpf(4) consumer (assuming the ioctl commands are being implemented).

Once BIOCLOCK is executed, the device becomes locked which prevents the
execution of ioctl(2) commands which can change the underly parameters of the
bpf(4) device. An example might be the setting of bpf(4) filter programs or
attaching to different network interfaces.

BIOCSETWF can be used to set write filters for outgoing packets. Currently if
a bpf(4) consumer is compromised, the bpf(4) descriptor can essentially be used
as a raw socket, regardless of consumer's UID. Write filters give users the
ability to constrain which packets can be sent through the bpf(4) descriptor.

These features are currently implemented by a couple programs which came from
OpenBSD, such as the new dhclient and pflogd.

-Modify bpf_setf(9) to accept a "cmd" parameter. This will be used to specify
 whether a read or write filter is to be set.
-Add a bpf(4) filter program as a parameter to bpf_movein(9) as we will run the
 filter program on the mbuf data once we move the packet in from user-space.
-Rather than execute two uiomove operations, (one for the link header and the
 other for the packet data), execute one and manually copy the linker header
 into the sockaddr structure via bcopy.
-Restructure bpf_setf to compensate for write filters, as well as read.
-Adjust bpf(4) stats structures to include a bd_locked member.

It should be noted that the FreeBSD and OpenBSD implementations differ a bit in
the sense that we unconditionally enforce the lock, where OpenBSD enforces it
only if the calling credential is not root.

Idea from:	OpenBSD
Reviewed by:	mlaier
2005-08-22 19:35:48 +00:00

159 lines
5.8 KiB
C

/*-
* Copyright (c) 1990, 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from the Stanford/CMU enet packet filter,
* (net/enet.c) distributed as part of 4.3BSD, and code contributed
* to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
* Berkeley Laboratory.
*
* 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.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* @(#)bpfdesc.h 8.1 (Berkeley) 6/10/93
*
* $FreeBSD$
*/
#ifndef _NET_BPFDESC_H_
#define _NET_BPFDESC_H_
#include <sys/callout.h>
#include <sys/selinfo.h>
#include <sys/queue.h>
#include <sys/conf.h>
#include <net/if.h>
/*
* Descriptor associated with each open bpf file.
*/
struct bpf_d {
LIST_ENTRY(bpf_d) bd_next; /* Linked list of descriptors */
/*
* Buffer slots: two mbuf clusters buffer the incoming packets.
* The model has three slots. Sbuf is always occupied.
* sbuf (store) - Receive interrupt puts packets here.
* hbuf (hold) - When sbuf is full, put cluster here and
* wakeup read (replace sbuf with fbuf).
* fbuf (free) - When read is done, put cluster here.
* On receiving, if sbuf is full and fbuf is 0, packet is dropped.
*/
caddr_t bd_sbuf; /* store slot */
caddr_t bd_hbuf; /* hold slot */
caddr_t bd_fbuf; /* free slot */
int bd_slen; /* current length of store buffer */
int bd_hlen; /* current length of hold buffer */
int bd_bufsize; /* absolute length of buffers */
struct bpf_if * bd_bif; /* interface descriptor */
u_long bd_rtout; /* Read timeout in 'ticks' */
struct bpf_insn *bd_rfilter; /* read filter code */
struct bpf_insn *bd_wfilter; /* write filter code */
u_long bd_rcount; /* number of packets received */
u_long bd_dcount; /* number of packets dropped */
u_char bd_promisc; /* true if listening promiscuously */
u_char bd_state; /* idle, waiting, or timed out */
u_char bd_immediate; /* true to return on packet arrival */
int bd_hdrcmplt; /* false to fill in src lladdr automatically */
int bd_seesent; /* true if bpf should see sent packets */
int bd_async; /* non-zero if packet reception should generate signal */
int bd_sig; /* signal to send upon packet reception */
struct sigio * bd_sigio; /* information for async I/O */
#if BSD < 199103
u_char bd_selcoll; /* true if selects collide */
int bd_timedout;
struct thread * bd_selthread; /* process that last selected us */
#else
u_char bd_pad; /* explicit alignment */
struct selinfo bd_sel; /* bsd select info */
#endif
struct mtx bd_mtx; /* mutex for this descriptor */
struct callout bd_callout; /* for BPF timeouts with select */
struct label *bd_label; /* MAC label for descriptor */
u_long bd_fcount; /* number of packets which matched filter */
pid_t bd_pid; /* PID which created descriptor */
char bd_pcomm[MAXCOMLEN + 1];
int bd_locked; /* true if descriptor is locked */
};
/* Values for bd_state */
#define BPF_IDLE 0 /* no select in progress */
#define BPF_WAITING 1 /* waiting for read timeout in select */
#define BPF_TIMED_OUT 2 /* read timeout has expired in select */
#define BPFD_LOCK(bd) mtx_lock(&(bd)->bd_mtx)
#define BPFD_UNLOCK(bd) mtx_unlock(&(bd)->bd_mtx)
#define BPFD_LOCK_ASSERT(bd) do { \
mtx_assert(&(bd)->bd_mtx, MA_OWNED); \
NET_ASSERT_GIANT(); \
} while (0)
/* Test whether a BPF is ready for read(). */
#define bpf_ready(bd) \
((bd)->bd_hlen != 0 || \
(((bd)->bd_immediate || (bd)->bd_state == BPF_TIMED_OUT) && \
(bd)->bd_slen != 0))
/*
* Descriptor associated with each attached hardware interface.
*/
struct bpf_if {
LIST_ENTRY(bpf_if) bif_next; /* list of all interfaces */
LIST_HEAD(, bpf_d) bif_dlist; /* descriptor list */
struct bpf_if **bif_driverp; /* pointer into softc */
u_int bif_dlt; /* link layer type */
u_int bif_hdrlen; /* length of header (with padding) */
struct ifnet *bif_ifp; /* corresponding interface */
struct mtx bif_mtx; /* mutex for interface */
};
/*
* External representation of the bpf descriptor
*/
struct xbpf_d {
u_char bd_promisc;
u_char bd_immediate;
int bd_hdrcmplt;
int bd_seesent;
int bd_async;
u_long bd_rcount;
u_long bd_dcount;
u_long bd_fcount;
int bd_sig;
int bd_slen;
int bd_hlen;
int bd_bufsize;
pid_t bd_pid;
char bd_ifname[IFNAMSIZ];
char bd_pcomm[MAXCOMLEN + 1];
int bd_locked;
};
#define BPFIF_LOCK(bif) mtx_lock(&(bif)->bif_mtx)
#define BPFIF_UNLOCK(bif) mtx_unlock(&(bif)->bif_mtx)
#endif