ng_bpf.c

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/*
 * 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>
 *
 * $FreeBSD$
 * $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);
}