text: /*
   * ng_bpf.c
   */
  
  /*-
   * Copyright (c) 1999 Whistle Communications, Inc.
   * All rights reserved.
   * 
   * Subject to the following obligations and disclaimer of warranty, use and
   * redistribution of this software, in source or object code forms, with or
   * without modifications are expressly permitted by Whistle Communications;
   * provided, however, that:
   * 1. Any and all reproductions of the source or object code must include the
   *    copyright notice above and the following disclaimer of warranties; and
   * 2. No rights are granted, in any manner or form, to use Whistle
   *    Communications, Inc. trademarks, including the mark "WHISTLE
   *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
   *    such appears in the above copyright notice or in the software.
   * 
   * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
   * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
   * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
   * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
   * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
   * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
   * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
   * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
   * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
   * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
   * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER 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 WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
   * OF SUCH DAMAGE.
   *
   * Author: Archie Cobbs <archie@freebsd.org>
   *
   * $FreeBSD: releng/9.3/sys/netgraph/ng_bpf.c 249132 2013-04-05 08:22:11Z mav $
   * $Whistle: ng_bpf.c,v 1.3 1999/12/03 20:30:23 archie Exp $
   */
  
  /*
   * BPF NETGRAPH NODE TYPE
   *
   * This node type accepts any number of hook connections.  With each hook
   * is associated a bpf(4) filter program, and two hook names (each possibly
   * the empty string).  Incoming packets are compared against the filter;
   * matching packets are delivered out the first named hook (or dropped if
   * the empty string), and non-matching packets are delivered out the second
   * named hook (or dropped if the empty string).
   *
   * Each hook also keeps statistics about how many packets have matched, etc.
   */
  
  #include "opt_bpf.h"
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/errno.h>
  #include <sys/kernel.h>
  #include <sys/malloc.h>
  #include <sys/mbuf.h>
  
  #include <net/bpf.h>
  #ifdef BPF_JITTER
  #include <net/bpf_jitter.h>
  #endif
  
  #include <netgraph/ng_message.h>
  #include <netgraph/netgraph.h>
  #include <netgraph/ng_parse.h>
  #include <netgraph/ng_bpf.h>
  
  #ifdef NG_SEPARATE_MALLOC
  static MALLOC_DEFINE(M_NETGRAPH_BPF, "netgraph_bpf", "netgraph bpf node");
  #else
  #define M_NETGRAPH_BPF M_NETGRAPH
  #endif
  
  #define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0))
  
  #define ERROUT(x)	do { error = (x); goto done; } while (0)
  
  /* Per hook private info */
  struct ng_bpf_hookinfo {
  	hook_p			hook;
  	hook_p			match;
  	hook_p			nomatch;
  	struct ng_bpf_hookprog	*prog;
  #ifdef BPF_JITTER
  	bpf_jit_filter		*jit_prog;
  #endif
  	struct ng_bpf_hookstat	stats;
  };
  typedef struct ng_bpf_hookinfo *hinfo_p;
  
  /* Netgraph methods */
  static ng_constructor_t	ng_bpf_constructor;
  static ng_rcvmsg_t	ng_bpf_rcvmsg;
  static ng_shutdown_t	ng_bpf_shutdown;
  static ng_newhook_t	ng_bpf_newhook;
  static ng_rcvdata_t	ng_bpf_rcvdata;
  static ng_disconnect_t	ng_bpf_disconnect;
  
  /* Maximum bpf program instructions */
  extern int	bpf_maxinsns;
  
  /* Internal helper functions */
  static int	ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp);
  
  /* Parse type for one struct bfp_insn */
  static const struct ng_parse_struct_field ng_bpf_insn_type_fields[] = {
  	{ "code",	&ng_parse_hint16_type	},
  	{ "jt",		&ng_parse_uint8_type	},
  	{ "jf",		&ng_parse_uint8_type	},
  	{ "k",		&ng_parse_uint32_type	},
  	{ NULL }
  };
  static const struct ng_parse_type ng_bpf_insn_type = {
  	&ng_parse_struct_type,
  	&ng_bpf_insn_type_fields
  };
  
  /* Parse type for the field 'bpf_prog' in struct ng_bpf_hookprog */
  static int
  ng_bpf_hookprogary_getLength(const struct ng_parse_type *type,
  	const u_char *start, const u_char *buf)
  {
  	const struct ng_bpf_hookprog *hp;
  
  	hp = (const struct ng_bpf_hookprog *)
  	    (buf - OFFSETOF(struct ng_bpf_hookprog, bpf_prog));
  	return hp->bpf_prog_len;
  }
  
  static const struct ng_parse_array_info ng_bpf_hookprogary_info = {
  	&ng_bpf_insn_type,
  	&ng_bpf_hookprogary_getLength,
  	NULL
  };
  static const struct ng_parse_type ng_bpf_hookprogary_type = {
  	&ng_parse_array_type,
  	&ng_bpf_hookprogary_info
  };
  
  /* Parse type for struct ng_bpf_hookprog */
  static const struct ng_parse_struct_field ng_bpf_hookprog_type_fields[]
  	= NG_BPF_HOOKPROG_TYPE_INFO(&ng_bpf_hookprogary_type);
  static const struct ng_parse_type ng_bpf_hookprog_type = {
  	&ng_parse_struct_type,
  	&ng_bpf_hookprog_type_fields
  };
  
  /* Parse type for struct ng_bpf_hookstat */
  static const struct ng_parse_struct_field ng_bpf_hookstat_type_fields[]
  	= NG_BPF_HOOKSTAT_TYPE_INFO;
  static const struct ng_parse_type ng_bpf_hookstat_type = {
  	&ng_parse_struct_type,
  	&ng_bpf_hookstat_type_fields
  };
  
  /* List of commands and how to convert arguments to/from ASCII */
  static const struct ng_cmdlist ng_bpf_cmdlist[] = {
  	{
  	  NGM_BPF_COOKIE,
  	  NGM_BPF_SET_PROGRAM,
  	  "setprogram",
  	  &ng_bpf_hookprog_type,
  	  NULL
  	},
  	{
  	  NGM_BPF_COOKIE,
  	  NGM_BPF_GET_PROGRAM,
  	  "getprogram",
  	  &ng_parse_hookbuf_type,
  	  &ng_bpf_hookprog_type
  	},
  	{
  	  NGM_BPF_COOKIE,
  	  NGM_BPF_GET_STATS,
  	  "getstats",
  	  &ng_parse_hookbuf_type,
  	  &ng_bpf_hookstat_type
  	},
  	{
  	  NGM_BPF_COOKIE,
  	  NGM_BPF_CLR_STATS,
  	  "clrstats",
  	  &ng_parse_hookbuf_type,
  	  NULL
  	},
  	{
  	  NGM_BPF_COOKIE,
  	  NGM_BPF_GETCLR_STATS,
  	  "getclrstats",
  	  &ng_parse_hookbuf_type,
  	  &ng_bpf_hookstat_type
  	},
  	{ 0 }
  };
  
  /* Netgraph type descriptor */
  static struct ng_type typestruct = {
  	.version =	NG_ABI_VERSION,
  	.name =		NG_BPF_NODE_TYPE,
  	.constructor =	ng_bpf_constructor,
  	.rcvmsg =	ng_bpf_rcvmsg,
  	.shutdown =	ng_bpf_shutdown,
  	.newhook =	ng_bpf_newhook,
  	.rcvdata =	ng_bpf_rcvdata,
  	.disconnect =	ng_bpf_disconnect,
  	.cmdlist =	ng_bpf_cmdlist,
  };
  NETGRAPH_INIT(bpf, &typestruct);
  
  /* Default BPF program for a hook that matches nothing */
  static const struct ng_bpf_hookprog ng_bpf_default_prog = {
  	{ '\0' },		/* to be filled in at hook creation time */
  	{ '\0' },
  	{ '\0' },
  	1,
  	{ BPF_STMT(BPF_RET+BPF_K, 0) }
  };
  
  /*
   * Node constructor
   *
   * We don't keep any per-node private data
   * We go via the hooks.
   */
  static int
  ng_bpf_constructor(node_p node)
  {
  	NG_NODE_SET_PRIVATE(node, NULL);
  	return (0);
  }
  
  /*
   * Callback functions to be used by NG_NODE_FOREACH_HOOK() macro.
   */
  static int
  ng_bpf_addrefs(hook_p hook, void* arg)
  {
  	hinfo_p hip = NG_HOOK_PRIVATE(hook);
  	hook_p h = (hook_p)arg;
  
  	if (strcmp(hip->prog->ifMatch, NG_HOOK_NAME(h)) == 0)
  	    hip->match = h;
  	if (strcmp(hip->prog->ifNotMatch, NG_HOOK_NAME(h)) == 0)
  	    hip->nomatch = h;
  	return (1);
  }
  
  static int
  ng_bpf_remrefs(hook_p hook, void* arg)
  {
  	hinfo_p hip = NG_HOOK_PRIVATE(hook);
  	hook_p h = (hook_p)arg;
  
  	if (hip->match == h)
  	    hip->match = NULL;
  	if (hip->nomatch == h)
  	    hip->nomatch = NULL;
  	return (1);
  }
  
  /*
   * Add a hook
   */
  static int
  ng_bpf_newhook(node_p node, hook_p hook, const char *name)
  {
  	hinfo_p hip;
  	hook_p tmp;
  	int error;
  
  	/* Create hook private structure */
  	hip = malloc(sizeof(*hip), M_NETGRAPH_BPF, M_NOWAIT | M_ZERO);
  	if (hip == NULL)
  		return (ENOMEM);
  	hip->hook = hook;
  	NG_HOOK_SET_PRIVATE(hook, hip);
  
  	/* Add our reference into other hooks data. */
  	NG_NODE_FOREACH_HOOK(node, ng_bpf_addrefs, hook, tmp);
  
  	/* Attach the default BPF program */
  	if ((error = ng_bpf_setprog(hook, &ng_bpf_default_prog)) != 0) {
  		free(hip, M_NETGRAPH_BPF);
  		NG_HOOK_SET_PRIVATE(hook, NULL);
  		return (error);
  	}
  
  	/* Set hook name */
  	strlcpy(hip->prog->thisHook, name, sizeof(hip->prog->thisHook));
  	return (0);
  }
  
  /*
   * Receive a control message
   */
  static int
  ng_bpf_rcvmsg(node_p node, item_p item, hook_p lasthook)
  {
  	struct ng_mesg *msg;
  	struct ng_mesg *resp = NULL;
  	int error = 0;
  
  	NGI_GET_MSG(item, msg);
  	switch (msg->header.typecookie) {
  	case NGM_BPF_COOKIE:
  		switch (msg->header.cmd) {
  		case NGM_BPF_SET_PROGRAM:
  		    {
  			struct ng_bpf_hookprog *const
  			    hp = (struct ng_bpf_hookprog *)msg->data;
  			hook_p hook;
  
  			/* Sanity check */
  			if (msg->header.arglen < sizeof(*hp)
  			    || msg->header.arglen
  			      != NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len))
  				ERROUT(EINVAL);
  
  			/* Find hook */
  			if ((hook = ng_findhook(node, hp->thisHook)) == NULL)
  				ERROUT(ENOENT);
  
  			/* Set new program */
  			if ((error = ng_bpf_setprog(hook, hp)) != 0)
  				ERROUT(error);
  			break;
  		    }
  
  		case NGM_BPF_GET_PROGRAM:
  		    {
  			struct ng_bpf_hookprog *hp;
  			hook_p hook;
  
  			/* Sanity check */
  			if (msg->header.arglen == 0)
  				ERROUT(EINVAL);
  			msg->data[msg->header.arglen - 1] = '\0';
  
  			/* Find hook */
  			if ((hook = ng_findhook(node, msg->data)) == NULL)
  				ERROUT(ENOENT);
  
  			/* Build response */
  			hp = ((hinfo_p)NG_HOOK_PRIVATE(hook))->prog;
  			NG_MKRESPONSE(resp, msg,
  			    NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len), M_NOWAIT);
  			if (resp == NULL)
  				ERROUT(ENOMEM);
  			bcopy(hp, resp->data,
  			   NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len));
  			break;
  		    }
  
  		case NGM_BPF_GET_STATS:
  		case NGM_BPF_CLR_STATS:
  		case NGM_BPF_GETCLR_STATS:
  		    {
  			struct ng_bpf_hookstat *stats;
  			hook_p hook;
  
  			/* Sanity check */
  			if (msg->header.arglen == 0)
  				ERROUT(EINVAL);
  			msg->data[msg->header.arglen - 1] = '\0';
  
  			/* Find hook */
  			if ((hook = ng_findhook(node, msg->data)) == NULL)
  				ERROUT(ENOENT);
  			stats = &((hinfo_p)NG_HOOK_PRIVATE(hook))->stats;
  
  			/* Build response (if desired) */
  			if (msg->header.cmd != NGM_BPF_CLR_STATS) {
  				NG_MKRESPONSE(resp,
  				    msg, sizeof(*stats), M_NOWAIT);
  				if (resp == NULL)
  					ERROUT(ENOMEM);
  				bcopy(stats, resp->data, sizeof(*stats));
  			}
  
  			/* Clear stats (if desired) */
  			if (msg->header.cmd != NGM_BPF_GET_STATS)
  				bzero(stats, sizeof(*stats));
  			break;
  		    }
  
  		default:
  			error = EINVAL;
  			break;
  		}
  		break;
  	default:
  		error = EINVAL;
  		break;
  	}
  done:
  	NG_RESPOND_MSG(error, node, item, resp);
  	NG_FREE_MSG(msg);
  	return (error);
  }
  
  /*
   * Receive data on a hook
   *
   * Apply the filter, and then drop or forward packet as appropriate.
   */
  static int
  ng_bpf_rcvdata(hook_p hook, item_p item)
  {
  	const hinfo_p hip = NG_HOOK_PRIVATE(hook);
  	int totlen;
  	int needfree = 0, error = 0, usejit = 0;
  	u_char *data = NULL;
  	hinfo_p dhip;
  	hook_p dest;
  	u_int len;
  	struct mbuf *m;
  
  	m = NGI_M(item);	/* 'item' still owns it.. we are peeking */ 
  	totlen = m->m_pkthdr.len;
  	/* Update stats on incoming hook. XXX Can we do 64 bits atomically? */
  	/* atomic_add_int64(&hip->stats.recvFrames, 1); */
  	/* atomic_add_int64(&hip->stats.recvOctets, totlen); */
  	hip->stats.recvFrames++; 
  	hip->stats.recvOctets += totlen;
  
  	/* Don't call bpf_filter() with totlen == 0! */
  	if (totlen == 0) {
  		len = 0;
  		goto ready;
  	}
  
  #ifdef BPF_JITTER
  	if (bpf_jitter_enable != 0 && hip->jit_prog != NULL)
  		usejit = 1;
  #endif
  
  	/* Need to put packet in contiguous memory for bpf */
  	if (m->m_next != NULL && totlen > MHLEN) {
  		if (usejit) {
  			data = malloc(totlen, M_NETGRAPH_BPF, M_NOWAIT);
  			if (data == NULL) {
  				NG_FREE_ITEM(item);
  				return (ENOMEM);
  			}
  			needfree = 1;
  			m_copydata(m, 0, totlen, (caddr_t)data);
  		}
  	} else {
  		if (m->m_next != NULL) {
  			NGI_M(item) = m = m_pullup(m, totlen);
  			if (m == NULL) {
  				NG_FREE_ITEM(item);
  				return (ENOBUFS);
  			}
  		}
  		data = mtod(m, u_char *);
  	}
  
  	/* Run packet through filter */
  #ifdef BPF_JITTER
  	if (usejit)
  		len = (*(hip->jit_prog->func))(data, totlen, totlen);
  	else
  #endif
  	if (data)
  		len = bpf_filter(hip->prog->bpf_prog, data, totlen, totlen);
  	else
  		len = bpf_filter(hip->prog->bpf_prog, (u_char *)m, totlen, 0);
  	if (needfree)
  		free(data, M_NETGRAPH_BPF);
  ready:
  	/* See if we got a match and find destination hook */
  	if (len > 0) {
  
  		/* Update stats */
  		/* XXX atomically? */
  		hip->stats.recvMatchFrames++;
  		hip->stats.recvMatchOctets += totlen;
  
  		/* Truncate packet length if required by the filter */
  		/* Assume this never changes m */
  		if (len < totlen) {
  			m_adj(m, -(totlen - len));
  			totlen = len;
  		}
  		dest = hip->match;
  	} else
  		dest = hip->nomatch;
  	if (dest == NULL) {
  		NG_FREE_ITEM(item);
  		return (0);
  	}
  
  	/* Deliver frame out destination hook */
  	dhip = NG_HOOK_PRIVATE(dest);
  	dhip->stats.xmitOctets += totlen;
  	dhip->stats.xmitFrames++;
  	NG_FWD_ITEM_HOOK(error, item, dest);
  	return (error);
  }
  
  /*
   * Shutdown processing
   */
  static int
  ng_bpf_shutdown(node_p node)
  {
  	NG_NODE_UNREF(node);
  	return (0);
  }
  
  /*
   * Hook disconnection
   */
  static int
  ng_bpf_disconnect(hook_p hook)
  {
  	const node_p node = NG_HOOK_NODE(hook);
  	const hinfo_p hip = NG_HOOK_PRIVATE(hook);
  	hook_p tmp;
  
  	KASSERT(hip != NULL, ("%s: null info", __func__));
  
  	/* Remove our reference from other hooks data. */
  	NG_NODE_FOREACH_HOOK(node, ng_bpf_remrefs, hook, tmp);
  
  	free(hip->prog, M_NETGRAPH_BPF);
  #ifdef BPF_JITTER
  	if (hip->jit_prog != NULL)
  		bpf_destroy_jit_filter(hip->jit_prog);
  #endif
  	free(hip, M_NETGRAPH_BPF);
  	if ((NG_NODE_NUMHOOKS(node) == 0) &&
  	    (NG_NODE_IS_VALID(node))) {
  		ng_rmnode_self(node);
  	}
  	return (0);
  }
  
  /************************************************************************
  			HELPER STUFF
   ************************************************************************/
  
  /*
   * Set the BPF program associated with a hook
   */
  static int
  ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp0)
  {
  	const hinfo_p hip = NG_HOOK_PRIVATE(hook);
  	struct ng_bpf_hookprog *hp;
  #ifdef BPF_JITTER
  	bpf_jit_filter *jit_prog;
  #endif
  	int size;
  
  	/* Check program for validity */
  	if (hp0->bpf_prog_len > bpf_maxinsns ||
  	    !bpf_validate(hp0->bpf_prog, hp0->bpf_prog_len))
  		return (EINVAL);
  
  	/* Make a copy of the program */
  	size = NG_BPF_HOOKPROG_SIZE(hp0->bpf_prog_len);
  	hp = malloc(size, M_NETGRAPH_BPF, M_NOWAIT);
  	if (hp == NULL)
  		return (ENOMEM);
  	bcopy(hp0, hp, size);
  #ifdef BPF_JITTER
  	jit_prog = bpf_jitter(hp->bpf_prog, hp->bpf_prog_len);
  #endif
  
  	/* Free previous program, if any, and assign new one */
  	if (hip->prog != NULL)
  		free(hip->prog, M_NETGRAPH_BPF);
  	hip->prog = hp;
  #ifdef BPF_JITTER
  	if (hip->jit_prog != NULL)
  		bpf_destroy_jit_filter(hip->jit_prog);
  	hip->jit_prog = jit_prog;
  #endif
  
  	/* Prepare direct references on target hooks. */
  	hip->match = ng_findhook(NG_HOOK_NODE(hook), hip->prog->ifMatch);
  	hip->nomatch = ng_findhook(NG_HOOK_NODE(hook), hip->prog->ifNotMatch);
  	return (0);
  }
  