Remove building with NOCRYPTO option

[minix3.git] / minix / net / lwip / bpfdev.c

/* LWIP service - bpfdev.c - Berkeley Packet Filter (/dev/bpf) interface */
/*
 * BPF is a cloning device: opening /dev/bpf returns a new BPF device which is
 * independent from any other opened BPF devices.  We assume that each BPF
 * device is used by one single user process, and this implementation therefore
 * does not support multiple concurrent device calls on the same BPF device.
 *
 * Packet buffering basically follows the BSD model: each BPF device that is
 * configured (that is, it has been attached to an interface) has two buffers,
 * each of the configured size: a store buffer, where new packets are stored,
 * and a hold buffer, which is typically full and awaiting retrieval through a
 * read call from userland.  The buffers are swapped ("rotated") when the store
 * buffer is filled up and the hold buffer is empty - if the hold buffer is not
 * empty is not empty either, additional packets are dropped.
 *
 * These buffers are allocated when the BPF device is attached to an interface.
 * The interface may later disappear, in which case the BPF device is detached
 * from it, allowing any final packets to be read before read requests start
 * returning I/O errors.  The buffers are freed only when the device is closed.
 */

#include "lwip.h"
#include "bpfdev.h"

#include <minix/chardriver.h>
#include <net/if.h>
#include <net/bpfdesc.h>
#include <minix/bpf.h>
#include <sys/mman.h>

/*
 * Make sure that our implementation matches the BPF version in the NetBSD
 * headers.  If they change the version number, we may have to make changes
 * here accordingly.
 */
#if BPF_MAJOR_VERSION != 1 || BPF_MINOR_VERSION != 1
#error "NetBSD BPF version has changed"
#endif

/* The number of BPF devices. */
#define NR_BPFDEV               16

/* BPF receive buffer size: allowed range and default. */
#define BPF_BUF_MIN             BPF_WORDALIGN(sizeof(struct bpf_hdr))
#define BPF_BUF_DEF             32768
#define BPF_BUF_MAX             262144

/*
 * By opening /dev/bpf, one will obtain a cloned device with a different minor
 * number, which maps to one of the BPF devices.
 */
#define BPFDEV_MINOR            0       /* minor number of /dev/bpf */
#define BPFDEV_BASE_MINOR       1       /* base minor number for BPF devices */

static struct bpfdev {
        struct bpfdev_link bpf_link;    /* structure link, MUST be first */
        TAILQ_ENTRY(bpfdev) bpf_next;   /* next on free or interface list */
        struct ifdev *bpf_ifdev;        /* associated interface, or NULL */
        unsigned int bpf_flags;         /* flags (BPFF_) */
        size_t bpf_size;                /* size of packet buffers */
        char *bpf_sbuf;                 /* store buffer (mmap'd, or NULL) */
        char *bpf_hbuf;                 /* hold buffer (mmap'd, or NULL) */
        size_t bpf_slen;                /* used part of store buffer */
        size_t bpf_hlen;                /* used part of hold buffer */
        struct bpf_insn *bpf_filter;    /* verified BPF filter, or NULL */
        size_t bpf_filterlen;           /* length of filter, for munmap */
        pid_t bpf_pid;                  /* process ID of last using process */
        clock_t bpf_timeout;            /* timeout for read calls (0 = none) */
        struct {                        /* state for pending read request */
                endpoint_t br_endpt;    /* reading endpoint, or NONE */
                cp_grant_id_t br_grant; /* grant for reader's buffer */
                cdev_id_t br_id;        /* read request identifier */
                minix_timer_t br_timer; /* timer for read timeout */
        } bpf_read;
        struct {                        /* state for pending select request */
                endpoint_t bs_endpt;    /* selecting endpoint, or NONE */
                unsigned int bs_selops; /* pending select operations */
        } bpf_select;
        struct {                        /* packet capture statistics */
                uint64_t bs_recv;       /* # of packets run through filter */
                uint64_t bs_drop;       /* # of packets dropped: buffer full */
                uint64_t bs_capt;       /* # of packets accepted by filter */
        } bpf_stat;
} bpf_array[NR_BPFDEV];

#define BPFF_IN_USE     0x01            /* this BPF device object is in use */
#define BPFF_PROMISC    0x02            /* promiscuous mode enabled */
#define BPFF_IMMEDIATE  0x04            /* immediate mode is enabled */
#define BPFF_SEESENT    0x08            /* also process host-sent packets */
#define BPFF_HDRCMPLT   0x10            /* do not fill in link-layer source */
#define BPFF_FEEDBACK   0x20            /* feed back written packet as input */

static TAILQ_HEAD(, bpfdev_link) bpfl_freelist; /* list of free BPF devices */

static struct bpf_stat bpf_stat;

static ssize_t bpfdev_peers(struct rmib_call *, struct rmib_node *,
        struct rmib_oldp *, struct rmib_newp *);

/* The CTL_NET NET_BPF subtree.  All nodes are dynamically numbered. */
static struct rmib_node net_bpf_table[] = {
        RMIB_INT(RMIB_RO, BPF_BUF_MAX, "maxbufsize",
            "Maximum size for data capture buffer"), /* TODO: read-write */
        RMIB_STRUCT(RMIB_RO, sizeof(bpf_stat), &bpf_stat, "stats",
            "BPF stats"),
        RMIB_FUNC(RMIB_RO | CTLTYPE_NODE, 0, bpfdev_peers, "peers",
            "BPF peers"),
};

static struct rmib_node net_bpf_node =
    RMIB_NODE(RMIB_RO, net_bpf_table, "bpf", "BPF options");

/*
 * Initialize the BPF module.
 */
void
bpfdev_init(void)
{
        const int mib[] = { CTL_NET, NET_BPF };
        unsigned int slot;
        int r;

        /* Initialize data structures. */
        TAILQ_INIT(&bpfl_freelist);

        for (slot = 0; slot < __arraycount(bpf_array); slot++) {
                bpf_array[slot].bpf_flags = 0;

                TAILQ_INSERT_TAIL(&bpfl_freelist, &bpf_array[slot].bpf_link,
                    bpfl_next);
        }

        memset(&bpf_stat, 0, sizeof(bpf_stat));

        /* Register the "net.bpf" subtree with the MIB service. */
        if ((r = rmib_register(mib, __arraycount(mib), &net_bpf_node)) != OK)
                panic("unable to register net.bpf RMIB tree: %d", r);
}

/*
 * Given a BPF device object, return the corresponding minor number.
 */
static devminor_t
bpfdev_get_minor(struct bpfdev * bpfdev)
{

        assert(bpfdev != NULL);

        return BPFDEV_BASE_MINOR + (devminor_t)(bpfdev - bpf_array);
}

/*
 * Given a minor number, return the corresponding BPF device object, or NULL if
 * the minor number does not identify a BPF device.
 */
static struct bpfdev *
bpfdev_get_by_minor(devminor_t minor)
{

        if (minor < BPFDEV_BASE_MINOR ||
            (unsigned int)minor >= BPFDEV_BASE_MINOR + __arraycount(bpf_array))
                return NULL;

        return &bpf_array[minor - BPFDEV_BASE_MINOR];
}

/*
 * Open a BPF device, returning a cloned device instance.
 */
static int
bpfdev_open(devminor_t minor, int access __unused, endpoint_t user_endpt)
{
        struct bpfdev_link *bpfl;
        struct bpfdev *bpf;

        /* Disallow opening cloned devices through device nodes. */
        if (minor != BPFDEV_MINOR)
                return ENXIO;

        if (TAILQ_EMPTY(&bpfl_freelist))
                return ENOBUFS;

        bpfl = TAILQ_FIRST(&bpfl_freelist);
        TAILQ_REMOVE(&bpfl_freelist, bpfl, bpfl_next);

        bpf = (struct bpfdev *)bpfl;

        memset(bpf, 0, sizeof(*bpf));

        bpf->bpf_flags = BPFF_IN_USE | BPFF_SEESENT;
        bpf->bpf_size = BPF_BUF_DEF;
        bpf->bpf_pid = getnpid(user_endpt);
        bpf->bpf_read.br_endpt = NONE;
        bpf->bpf_select.bs_endpt = NONE;

        return CDEV_CLONED | bpfdev_get_minor(bpf);
}

/*
 * Close a BPF device.
 */
static int
bpfdev_close(devminor_t minor)
{
        struct bpfdev *bpf;

        if ((bpf = bpfdev_get_by_minor(minor)) == NULL)
                return EINVAL;

        /*
         * There cannot possibly be a pending read request, so we never need to
         * cancel the read timer from here either.
         */
        assert(bpf->bpf_read.br_endpt == NONE);

        if (bpf->bpf_sbuf != NULL) {
                assert(bpf->bpf_hbuf != NULL);

                if (munmap(bpf->bpf_sbuf, bpf->bpf_size) != 0)
                        panic("munmap failed: %d", -errno);
                if (munmap(bpf->bpf_hbuf, bpf->bpf_size) != 0)
                        panic("munmap failed: %d", -errno);

                bpf->bpf_sbuf = NULL;
                bpf->bpf_hbuf = NULL;
        } else
                assert(bpf->bpf_hbuf == NULL);

        if (bpf->bpf_filter != NULL) {
                assert(bpf->bpf_filterlen > 0);

                if (munmap(bpf->bpf_filter, bpf->bpf_filterlen) != 0)
                        panic("munmap failed: %d", -errno);

                bpf->bpf_filter = NULL;
        }

        /*
         * If the BPF device was attached to an interface, and that interface
         * has not disappeared in the meantime, detach from it now.
         */
        if (bpf->bpf_ifdev != NULL) {
                if (bpf->bpf_flags & BPFF_PROMISC)
                        ifdev_clear_promisc(bpf->bpf_ifdev);

                ifdev_detach_bpf(bpf->bpf_ifdev, &bpf->bpf_link);

                bpf->bpf_ifdev = NULL;
        }

        bpf->bpf_flags = 0;             /* mark as no longer in use */

        TAILQ_INSERT_HEAD(&bpfl_freelist, &bpf->bpf_link, bpfl_next);

        return OK;
}

/*
 * Rotate buffers for the BPF device, by swapping the store buffer and the hold
 * buffer.
 */
static void
bpfdev_rotate(struct bpfdev * bpf)
{
        char *buf;
        size_t len;

        /*
         * When rotating, the store buffer may or may not be empty, but the
         * hold buffer must always be empty.
         */
        assert(bpf->bpf_hlen == 0);

        buf = bpf->bpf_sbuf;
        len = bpf->bpf_slen;
        bpf->bpf_sbuf = bpf->bpf_hbuf;
        bpf->bpf_slen = bpf->bpf_hlen;
        bpf->bpf_hbuf = buf;
        bpf->bpf_hlen = len;
}

/*
 * Test whether any of the given select operations are ready on the BPF device,
 * and return the set of ready operations.
 */
static unsigned int
bpfdev_test_select(struct bpfdev * bpf, unsigned int ops)
{
        unsigned int ready_ops;

        ready_ops = 0;

        /*
         * The BPF device is ready for reading if the hold buffer is not empty
         * (i.e.: the store buffer has been filled up completely and was
         * therefore rotated) or if immediate mode is set and the store buffer
         * is not empty (i.e.: any packet is available at all).  In the latter
         * case, the buffers will be rotated during the read.  We do not
         * support applying the read timeout to selects and maintaining state
         * between the select and the following read, because despite that
         * libpcap claims that it is the right behavior, that is just insane.
         */
        if (ops & CDEV_OP_RD) {
                if (bpf->bpf_ifdev == NULL)
                        ready_ops |= CDEV_OP_RD;
                else if (bpf->bpf_hlen > 0)
                        ready_ops |= CDEV_OP_RD;
                else if ((bpf->bpf_flags & BPFF_IMMEDIATE) &&
                    bpf->bpf_slen > 0)
                        ready_ops |= CDEV_OP_RD;
        }

        if (ops & CDEV_OP_WR)
                ready_ops |= CDEV_OP_WR;

        return ready_ops;
}

/*
 * There has been a state change on the BPF device.  If now possible, resume a
 * pending select query, if any.
 */
static void
bpfdev_resume_select(struct bpfdev * bpf)
{
        unsigned int ops, ready_ops;
        endpoint_t endpt;

        /* First see if there is a pending select request at all. */
        if ((endpt = bpf->bpf_select.bs_endpt) == NONE)
                return;
        ops = bpf->bpf_select.bs_selops;

        assert(ops != 0);

        /* Then see if any of the pending operations are now ready. */
        if ((ready_ops = bpfdev_test_select(bpf, ops)) == 0)
                return;

        /* If so, notify VFS about the ready operations. */
        chardriver_reply_select(bpf->bpf_select.bs_endpt,
            bpfdev_get_minor(bpf), ready_ops);

        /*
         * Forget about the ready operations.  If that leaves no pending
         * operations, forget about the select request altogether.
         */
        if ((bpf->bpf_select.bs_selops &= ~ready_ops) == 0)
                bpf->bpf_select.bs_endpt = NONE;
}

/*
 * There has been a state change on the BPF device.  If now possible, resume a
 * pending read request, if any.  If the call is a result of a timeout,
 * 'is_timeout' is set.  In that case, the read request must be resumed with an
 * EAGAIN error if no packets are available, and the running timer must be
 * canceled.  Otherwise, the resumption is due to a full buffer or a
 * disappeared interface, and 'is_timeout' is not set.  In this case, the read
 * request must be resumed with an I/O error if no packets are available.
 */
static void
bpfdev_resume_read(struct bpfdev * bpf, int is_timeout)
{
        ssize_t r;

        assert(bpf->bpf_read.br_endpt != NONE);

        /*
         * If the hold buffer is still empty, see if the store buffer has
         * any packets to copy out.
         */
        if (bpf->bpf_hlen == 0)
                bpfdev_rotate(bpf);

        /* Return any available packets, or otherwise an error. */
        if (bpf->bpf_hlen > 0) {
                assert(bpf->bpf_hlen <= bpf->bpf_size);

                r = sys_safecopyto(bpf->bpf_read.br_endpt,
                    bpf->bpf_read.br_grant, 0, (vir_bytes)bpf->bpf_hbuf,
                    bpf->bpf_hlen);

                if (r == OK) {
                        r = (ssize_t)bpf->bpf_hlen;

                        bpf->bpf_hlen = 0;

                        assert(bpf->bpf_slen != bpf->bpf_size);

                        /*
                         * Allow readers to get the last packets after the
                         * interface has disappeared, before getting errors.
                         */
                        if (bpf->bpf_ifdev == NULL)
                                bpfdev_rotate(bpf);
                }
        } else
                r = (is_timeout) ? EAGAIN : EIO;

        chardriver_reply_task(bpf->bpf_read.br_endpt, bpf->bpf_read.br_id, r);

        bpf->bpf_read.br_endpt = NONE;

        /* Was there still a timer running?  Then cancel it now. */
        if (bpf->bpf_timeout > 0 && !is_timeout)
                cancel_timer(&bpf->bpf_read.br_timer);
}

/*
 * A read timeout has triggered for the BPF device.  Wake up the pending read
 * request.
 */
static void
bpfdev_timeout(int arg)
{
        struct bpfdev *bpf;

        assert(arg >= 0 && (unsigned int)arg < __arraycount(bpf_array));

        bpf = &bpf_array[arg];

        assert(bpf->bpf_read.br_endpt != NONE);

        bpfdev_resume_read(bpf, TRUE /*is_timeout*/);
}

/*
 * Read from a BPF device.
 */
static ssize_t
bpfdev_read(devminor_t minor, uint64_t position, endpoint_t endpt,
        cp_grant_id_t grant, size_t size, int flags, cdev_id_t id)
{
        struct bpfdev *bpf;
        ssize_t r;
        int suspend;

        if ((bpf = bpfdev_get_by_minor(minor)) == NULL)
                return EINVAL;

        /* Allow only one read call at a time. */
        if (bpf->bpf_read.br_endpt != NONE)
                return EIO;

        /* Has this BPF device been configured at all yet? */
        if (bpf->bpf_sbuf == NULL)
                return EINVAL;

        /*
         * Does the read call size match the entire buffer size?  This is a
         * ridiculous requirement but it makes our job quite a bit easier..
         */
        if (size != bpf->bpf_size)
                return EINVAL;

        /*
         * Following standard receive semantics, if the interface is gone,
         * return all the packets that were pending before returning an error.
         * This requires extra buffer rotations after read completion, too.
         */
        if (bpf->bpf_ifdev == NULL && bpf->bpf_hlen == 0)
                return EIO;

        /*
         * If immediate mode is not enabled, we should always suspend the read
         * call if the hold buffer is empty.  If immediate mode is enabled, we
         * should only suspend the read call if both buffers are empty, and
         * return data from the hold buffer or otherwise the store buffer,
         * whichever is not empty.  A non-blocking call behaves as though
         * immediate mode is enabled, except it will return EAGAIN instead of
         * suspending the read call if both buffers are empty.  Thus, we may
         * have to rotate buffers for both immediate mode and non-blocking
         * calls.  The latter is necessary for libpcap to behave correctly.
         */
        if ((flags & CDEV_NONBLOCK) || (bpf->bpf_flags & BPFF_IMMEDIATE))
                suspend = (bpf->bpf_hlen == 0 && bpf->bpf_slen == 0);
        else
                suspend = (bpf->bpf_hlen == 0);

        if (suspend) {
                if (flags & CDEV_NONBLOCK)
                        return EAGAIN;

                /* Suspend the read call for later. */
                bpf->bpf_read.br_endpt = endpt;
                bpf->bpf_read.br_grant = grant;
                bpf->bpf_read.br_id = id;

                /* Set a timer if requested. */
                if (bpf->bpf_timeout > 0)
                        set_timer(&bpf->bpf_read.br_timer, bpf->bpf_timeout,
                            bpfdev_timeout, (int)(bpf - bpf_array));

                return EDONTREPLY;
        }

        /* If we get here, either buffer has data; rotate buffers if needed. */
        if (bpf->bpf_hlen == 0)
                bpfdev_rotate(bpf);
        assert(bpf->bpf_hlen > 0);

        if ((r = sys_safecopyto(endpt, grant, 0, (vir_bytes)bpf->bpf_hbuf,
            bpf->bpf_hlen)) != OK)
                return r;

        r = (ssize_t)bpf->bpf_hlen;

        bpf->bpf_hlen = 0;

        /*
         * If the store buffer is exactly full, rotate it now.  Also, if the
         * interface has disappeared, the store buffer will never fill up.
         * Rotate it so that the application will get any remaining data before
         * getting errors about the interface being gone.
         */
        if (bpf->bpf_slen == bpf->bpf_size || bpf->bpf_ifdev == NULL)
                bpfdev_rotate(bpf);

        return r;
}

/*
 * Write to a BPF device.
 */
static ssize_t
bpfdev_write(devminor_t minor, uint64_t position, endpoint_t endpt,
        cp_grant_id_t grant, size_t size, int flags, cdev_id_t id)
{
        struct bpfdev *bpf;
        struct pbuf *pbuf, *pptr, *pcopy;
        size_t off;
        err_t err;
        int r;

        if ((bpf = bpfdev_get_by_minor(minor)) == NULL)
                return EINVAL;

        if (bpf->bpf_ifdev == NULL)
                return EINVAL;

        /* VFS skips zero-sized I/O calls right now, but that may change. */
        if (size == 0)
                return 0;       /* nothing to do */

        if (size > ifdev_get_hdrlen(bpf->bpf_ifdev) +
            ifdev_get_mtu(bpf->bpf_ifdev))
                return EMSGSIZE;

        if ((pbuf = pchain_alloc(PBUF_LINK, size)) == NULL)
                return ENOMEM;

        /* TODO: turn this into a series of vector copies. */
        off = 0;
        for (pptr = pbuf; pptr != NULL; pptr = pptr->next) {
                if ((r = sys_safecopyfrom(endpt, grant, off,
                    (vir_bytes)pptr->payload, pptr->len)) != OK) {
                        pbuf_free(pbuf);

                        return r;
                }
                off += pptr->len;
        }
        assert(off == size);

        /*
         * In feedback mode, we cannot use the same packet buffers for both
         * output and input, so make a copy.  We do this before calling the
         * output function, which may change part of the buffers, because the
         * BSDs take this approach as well.
         */
        if (bpf->bpf_flags & BPFF_FEEDBACK) {
                if ((pcopy = pchain_alloc(PBUF_LINK, size)) == NULL) {
                        pbuf_free(pbuf);

                        return ENOMEM;
                }

                if (pbuf_copy(pcopy, pbuf) != ERR_OK)
                        panic("unexpected pbuf copy failure");
        } else
                pcopy = NULL;

        /* Pass in the packet as output, and free it again. */
        err = ifdev_output(bpf->bpf_ifdev, pbuf, NULL /*netif*/,
            TRUE /*to_bpf*/, !!(bpf->bpf_flags & BPFF_HDRCMPLT));

        pbuf_free(pbuf);

        /* In feedback mode, pass in the copy as input, if output succeeded. */
        if (err == ERR_OK && (bpf->bpf_flags & BPFF_FEEDBACK))
                ifdev_input(bpf->bpf_ifdev, pcopy, NULL /*netif*/,
                    FALSE /*to_bpf*/);
        else if (pcopy != NULL)
                pbuf_free(pcopy);

        return (err == ERR_OK) ? (ssize_t)size : util_convert_err(err);
}

/*
 * Attach a BPF device to a network interface, using the interface name given
 * in an ifreq structure.  As side effect, allocate hold and store buffers for
 * the device.  These buffers will stay allocated until the device is closed,
 * even though the interface may disappear before that.  Return OK if the BPF
 * device was successfully attached to the interface, or a negative error code
 * otherwise.
 */
static int
bpfdev_attach(struct bpfdev * bpf, struct ifreq * ifr)
{
        struct ifdev *ifdev;
        void *sbuf, *hbuf;

        /* Find the interface with the given name. */
        ifr->ifr_name[sizeof(ifr->ifr_name) - 1] = '\0';
        if ((ifdev = ifdev_find_by_name(ifr->ifr_name)) == NULL)
                return ENXIO;

        /*
         * Allocate a store buffer and a hold buffer.  Preallocate the memory,
         * or we might get killed later during low-memory conditions.
         */
        if ((sbuf = (char *)mmap(NULL, bpf->bpf_size, PROT_READ | PROT_WRITE,
            MAP_ANON | MAP_PRIVATE | MAP_PREALLOC, -1, 0)) == MAP_FAILED)
                return ENOMEM;

        if ((hbuf = (char *)mmap(NULL, bpf->bpf_size, PROT_READ | PROT_WRITE,
            MAP_ANON | MAP_PRIVATE | MAP_PREALLOC, -1, 0)) == MAP_FAILED) {
                (void)munmap(sbuf, bpf->bpf_size);

                return ENOMEM;
        }

        bpf->bpf_ifdev = ifdev;
        bpf->bpf_sbuf = sbuf;
        bpf->bpf_hbuf = hbuf;
        assert(bpf->bpf_slen == 0);
        assert(bpf->bpf_hlen == 0);

        ifdev_attach_bpf(ifdev, &bpf->bpf_link);

        return OK;
}

/*
 * Detach the BPF device from its interface, which is about to disappear.
 */
void
bpfdev_detach(struct bpfdev_link * bpfl)
{
        struct bpfdev *bpf = (struct bpfdev *)bpfl;

        assert(bpf->bpf_flags & BPFF_IN_USE);
        assert(bpf->bpf_ifdev != NULL);

        /*
         * We deliberately leave the buffers allocated here, for two reasons:
         *
         * 1) it lets applications to read any last packets in the buffers;
         * 2) it prevents reattaching the BPF device to another interface.
         */
        bpf->bpf_ifdev = NULL;

        /*
         * Resume pending read and select requests, returning any data left,
         * or an error if none.
         */
        if (bpf->bpf_hlen == 0)
                bpfdev_rotate(bpf);

        if (bpf->bpf_read.br_endpt != NONE)
                bpfdev_resume_read(bpf, FALSE /*is_timeout*/);

        bpfdev_resume_select(bpf);
}

/*
 * Flush the given BPF device, resetting its buffer contents and statistics
 * counters.
 */
static void
bpfdev_flush(struct bpfdev * bpf)
{

        bpf->bpf_slen = 0;
        bpf->bpf_hlen = 0;

        bpf->bpf_stat.bs_recv = 0;
        bpf->bpf_stat.bs_drop = 0;
        bpf->bpf_stat.bs_capt = 0;
}

/*
 * Install a filter program on the BPF device.  A new filter replaces any old
 * one.  A zero-sized filter simply clears a previous filter.  On success,
 * perform a flush and return OK.  On failure, return a negative error code
 * without making any modifications to the current filter.
 */
static int
bpfdev_setfilter(struct bpfdev * bpf, endpoint_t endpt, cp_grant_id_t grant)
{
        struct bpf_insn *filter;
        unsigned int count;
        size_t len;
        int r;

        if ((r = sys_safecopyfrom(endpt, grant,
            offsetof(struct minix_bpf_program, mbf_len), (vir_bytes)&count,
            sizeof(count))) != OK)
                return r;

        if (count > BPF_MAXINSNS)
                return EINVAL;
        len = count * sizeof(struct bpf_insn);

        if (len > 0) {
                if ((filter = (struct bpf_insn *)mmap(NULL, len,
                    PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0)) ==
                    MAP_FAILED)
                        return ENOMEM;

                if ((r = sys_safecopyfrom(endpt, grant,
                    offsetof(struct minix_bpf_program, mbf_insns),
                    (vir_bytes)filter, len)) != OK) {
                        (void)munmap(filter, len);

                        return r;
                }

                if (!bpf_validate(filter, count)) {
                        (void)munmap(filter, len);

                        return EINVAL;
                }
        } else
                filter = NULL;

        if (bpf->bpf_filter != NULL)
                (void)munmap(bpf->bpf_filter, bpf->bpf_filterlen);

        bpf->bpf_filter = filter;
        bpf->bpf_filterlen = len;

        bpfdev_flush(bpf);

        return OK;
}

/*
 * Process an I/O control request on the BPF device.
 */
static int
bpfdev_ioctl(devminor_t minor, unsigned long request, endpoint_t endpt,
        cp_grant_id_t grant, int flags, endpoint_t user_endpt, cdev_id_t id)
{
        struct bpfdev *bpf;
        struct bpf_stat bs;
        struct bpf_version bv;
        struct bpf_dltlist bfl;
        struct timeval tv;
        struct ifreq ifr;
        unsigned int uval;
        int r, val;

        if ((bpf = bpfdev_get_by_minor(minor)) == NULL)
                return EINVAL;

        /*
         * We do not support multiple concurrent requests in this module.  That
         * not only means that we forbid a read(2) call on a BPF device object
         * while another read(2) is already pending: we also disallow IOCTL
         * IOCTL calls while such a read(2) call is in progress.  This
         * restriction should never be a problem for user programs, and allows
         * us to rely on the fact that that no settings can change between the
         * start and end of any read call.  As a side note, pending select(2)
         * queries may be similarly affected, and will also not be fully
         * accurate if any options are changed while pending.
         */
        if (bpf->bpf_read.br_endpt != NONE)
                return EIO;

        bpf->bpf_pid = getnpid(user_endpt);

        /* These are in order of the NetBSD BIOC.. IOCTL numbers. */
        switch (request) {
        case BIOCGBLEN:
                uval = bpf->bpf_size;

                return sys_safecopyto(endpt, grant, 0, (vir_bytes)&uval,
                    sizeof(uval));

        case BIOCSBLEN:
                if (bpf->bpf_sbuf != NULL)
                        return EINVAL;

                if ((r = sys_safecopyfrom(endpt, grant, 0, (vir_bytes)&uval,
                    sizeof(uval))) != OK)
                        return r;

                if (uval < BPF_BUF_MIN)
                        uval = BPF_BUF_MIN;
                else if (uval > BPF_BUF_MAX)
                        uval = BPF_BUF_MAX;

                /* Is this the right thing to do?  It doesn't matter for us. */
                uval = BPF_WORDALIGN(uval);

                if ((r = sys_safecopyto(endpt, grant, 0, (vir_bytes)&uval,
                    sizeof(uval))) != OK)
                        return r;

                bpf->bpf_size = uval;

                return OK;

        case MINIX_BIOCSETF:
                return bpfdev_setfilter(bpf, endpt, grant);

        case BIOCPROMISC:
                if (bpf->bpf_ifdev == NULL)
                        return EINVAL;

                if (!(bpf->bpf_flags & BPFF_PROMISC)) {
                        if (!ifdev_set_promisc(bpf->bpf_ifdev))
                                return EINVAL;

                        bpf->bpf_flags |= BPFF_PROMISC;
                }

                return OK;

        case BIOCFLUSH:
                bpfdev_flush(bpf);

                return OK;

        case BIOCGDLT:
                if (bpf->bpf_ifdev == NULL)
                        return EINVAL;

                /* TODO: support for type configuration per BPF device. */
                uval = ifdev_get_dlt(bpf->bpf_ifdev);

                return sys_safecopyto(endpt, grant, 0, (vir_bytes)&uval,
                    sizeof(uval));

        case BIOCGETIF:
                if (bpf->bpf_ifdev == NULL)
                        return EINVAL;

                memset(&ifr, 0, sizeof(ifr));
                strlcpy(ifr.ifr_name, ifdev_get_name(bpf->bpf_ifdev),
                    sizeof(ifr.ifr_name));

                return sys_safecopyto(endpt, grant, 0, (vir_bytes)&ifr,
                    sizeof(ifr));

        case BIOCSETIF:
                /*
                 * Test on the presence of a buffer rather than on an interface
                 * since the latter may disappear and thus be reset to NULL, in
                 * which case we do not want to allow rebinding to another.
                 */
                if (bpf->bpf_sbuf != NULL)
                        return EINVAL;

                if ((r = sys_safecopyfrom(endpt, grant, 0, (vir_bytes)&ifr,
                    sizeof(ifr))) != OK)
                        return r;

                return bpfdev_attach(bpf, &ifr);

        case BIOCGSTATS:
                /*
                 * Why do we not embed a bpf_stat structure directly in the
                 * BPF device structure?  Well, bpf_stat has massive padding..
                 */
                memset(&bs, 0, sizeof(bs));
                bs.bs_recv = bpf->bpf_stat.bs_recv;
                bs.bs_drop = bpf->bpf_stat.bs_drop;
                bs.bs_capt = bpf->bpf_stat.bs_capt;

                return sys_safecopyto(endpt, grant, 0, (vir_bytes)&bs,
                    sizeof(bs));

        case BIOCIMMEDIATE:
                if ((r = sys_safecopyfrom(endpt, grant, 0, (vir_bytes)&uval,
                    sizeof(uval))) != OK)
                        return r;

                if (uval)
                        bpf->bpf_flags |= BPFF_IMMEDIATE;
                else
                        bpf->bpf_flags &= ~BPFF_IMMEDIATE;

                return OK;

        case BIOCVERSION:
                memset(&bv, 0, sizeof(bv));
                bv.bv_major = BPF_MAJOR_VERSION;
                bv.bv_minor = BPF_MINOR_VERSION;

                return sys_safecopyto(endpt, grant, 0, (vir_bytes)&bv,
                    sizeof(bv));

        case BIOCGHDRCMPLT:
                uval = !!(bpf->bpf_flags & BPFF_HDRCMPLT);

                return sys_safecopyto(endpt, grant, 0, (vir_bytes)&uval,
                    sizeof(uval));

        case BIOCSHDRCMPLT:
                if ((r = sys_safecopyfrom(endpt, grant, 0, (vir_bytes)&uval,
                    sizeof(uval))) != OK)
                        return r;

                if (uval)
                        bpf->bpf_flags |= BPFF_HDRCMPLT;
                else
                        bpf->bpf_flags &= ~BPFF_HDRCMPLT;

                return OK;

        case BIOCSDLT:
                if (bpf->bpf_ifdev == NULL)
                        return EINVAL;

                if ((r = sys_safecopyfrom(endpt, grant, 0, (vir_bytes)&uval,
                    sizeof(uval))) != OK)
                        return r;

                /* TODO: support for type configuration per BPF device. */
                if (uval != ifdev_get_dlt(bpf->bpf_ifdev))
                        return EINVAL;

                return OK;

        case MINIX_BIOCGDLTLIST:
                if (bpf->bpf_ifdev == NULL)
                        return EINVAL;

                if ((r = sys_safecopyfrom(endpt, grant, 0, (vir_bytes)&bfl,
                    sizeof(bfl))) != OK)
                        return r;

                if (bfl.bfl_list != NULL) {
                        if (bfl.bfl_len < 1)
                                return ENOMEM;

                        /*
                         * Copy out the 'list', which consists of one entry.
                         * If we were to produce multiple entries, we would
                         * have to check against the MINIX_BPF_MAXDLT limit.
                         */
                        uval = ifdev_get_dlt(bpf->bpf_ifdev);

                        if ((r = sys_safecopyto(endpt, grant,
                            offsetof(struct minix_bpf_dltlist, mbfl_list),
                            (vir_bytes)&uval, sizeof(uval))) != OK)
                                return r;
                }
                bfl.bfl_len = 1;

                return sys_safecopyto(endpt, grant, 0, (vir_bytes)&bfl,
                    sizeof(bfl));

        case BIOCGSEESENT:
                uval = !!(bpf->bpf_flags & BPFF_SEESENT);

                return sys_safecopyto(endpt, grant, 0, (vir_bytes)&uval,
                    sizeof(uval));

        case BIOCSSEESENT:
                if ((r = sys_safecopyfrom(endpt, grant, 0, (vir_bytes)&uval,
                    sizeof(uval))) != OK)
                        return r;

                if (uval)
                        bpf->bpf_flags |= BPFF_SEESENT;
                else
                        bpf->bpf_flags &= ~BPFF_SEESENT;

                return OK;

        case BIOCSRTIMEOUT:
                if ((r = sys_safecopyfrom(endpt, grant, 0, (vir_bytes)&tv,
                    sizeof(tv))) != OK)
                        return r;

                if ((r = util_timeval_to_ticks(&tv, &bpf->bpf_timeout)) != OK)
                        return r;

                return OK;

        case BIOCGRTIMEOUT:
                util_ticks_to_timeval(bpf->bpf_timeout, &tv);

                return sys_safecopyto(endpt, grant, 0, (vir_bytes)&tv,
                    sizeof(tv));

        case BIOCGFEEDBACK:
                uval = !!(bpf->bpf_flags & BPFF_FEEDBACK);

                return sys_safecopyto(endpt, grant, 0, (vir_bytes)&uval,
                    sizeof(uval));

        case BIOCSFEEDBACK:
                if ((r = sys_safecopyfrom(endpt, grant, 0, (vir_bytes)&uval,
                    sizeof(uval))) != OK)
                        return r;

                if (uval)
                        bpf->bpf_flags |= BPFF_FEEDBACK;
                else
                        bpf->bpf_flags &= ~BPFF_FEEDBACK;

                return OK;

        case FIONREAD:
                val = 0;
                if (bpf->bpf_hlen > 0)
                        val = bpf->bpf_hlen;
                else if ((bpf->bpf_flags & BPFF_IMMEDIATE) &&
                    bpf->bpf_slen > 0)
                        val = bpf->bpf_slen;
                else
                        val = 0;

                return sys_safecopyto(endpt, grant, 0, (vir_bytes)&val,
                    sizeof(val));

        default:
                return ENOTTY;
        }
}

/*
 * Cancel a previously suspended request on a BPF device.  Since only read
 * requests may be suspended (select is handled differently), the cancel
 * request must be for a read request.  Note that character devices currently
 * (still) behave slightly differently from socket devices here: while socket
 * drivers are supposed to respond to the original request, character drivers
 * must respond to the original request from the cancel callback.
 */
static int
bpfdev_cancel(devminor_t minor, endpoint_t endpt, cdev_id_t id)
{
        struct bpfdev *bpf;

        if ((bpf = bpfdev_get_by_minor(minor)) == NULL)
                return EDONTREPLY;

        /* Is this a cancel request for the currently pending read request? */
        if (bpf->bpf_read.br_endpt != endpt || bpf->bpf_read.br_id != id)
                return EDONTREPLY;

        /* If so, cancel the read request. */
        if (bpf->bpf_timeout > 0)
                cancel_timer(&bpf->bpf_read.br_timer);

        bpf->bpf_read.br_endpt = NONE;

        return EINTR; /* the return value for the canceled read request */
}

/*
 * Perform a select query on a BPF device.
 */
static int
bpfdev_select(devminor_t minor, unsigned int ops, endpoint_t endpt)
{
        struct bpfdev *bpf;
        unsigned int r, notify;

        if ((bpf = bpfdev_get_by_minor(minor)) == NULL)
                return EINVAL;

        notify = (ops & CDEV_NOTIFY);
        ops &= (CDEV_OP_RD | CDEV_OP_WR | CDEV_OP_ERR);

        r = bpfdev_test_select(bpf, ops);

        /*
         * For the operations that were not immediately ready, if requested,
         * save the select request for later.
         */
        ops &= ~r;

        if (ops != 0 && notify) {
                if (bpf->bpf_select.bs_endpt != NONE) {
                        /* Merge in the operations with any earlier request. */
                        if (bpf->bpf_select.bs_endpt != endpt)
                                return EIO;
                        bpf->bpf_select.bs_selops |= ops;
                } else {
                        bpf->bpf_select.bs_endpt = endpt;
                        bpf->bpf_select.bs_selops = ops;
                }
        }

        return r;
}

/*
 * Process an incoming packet on the interface to which the given BPF device is
 * attached.  If the packet passes the filter (if any), store as much as
 * requested of it in the store buffer, rotating buffers if needed and resuming
 * suspended read and select requests as appropriate.  This function is also
 * called through bpfdev_output() below.
 */
void
bpfdev_input(struct bpfdev_link * bpfl, const struct pbuf * pbuf)
{
        struct bpfdev *bpf = (struct bpfdev *)bpfl;
        struct timespec ts;
        struct bpf_hdr bh;
        const struct pbuf *pptr;
        size_t caplen, hdrlen, totlen, off, chunk;
        int hfull;

        /*
         * Apparently bs_recv is the counter of packets that were run through
         * the filter, not the number of packets that were or could be received
         * by the user (which is what I got from the manual page.. oh well).
         */
        bpf->bpf_stat.bs_recv++;
        bpf_stat.bs_recv++;

        /*
         * Run the packet through the BPF device's filter to see whether the
         * packet should be stored and if so, how much of it.  If no filter is
         * set, all packets will be stored in their entirety.
         */
        caplen = bpf_filter_ext(bpf->bpf_filter, pbuf, (u_char *)pbuf->payload,
            pbuf->tot_len, pbuf->len);

        if (caplen == 0)
                return;         /* no match; ignore packet */

        if (caplen > pbuf->tot_len)
                caplen = pbuf->tot_len;

        /* Truncate packet entries to the full size of the buffers. */
        hdrlen = BPF_WORDALIGN(sizeof(bh));
        totlen = BPF_WORDALIGN(hdrlen + caplen);

        if (totlen > bpf->bpf_size) {
                totlen = bpf->bpf_size;
                caplen = totlen - hdrlen;
        }
        assert(totlen >= hdrlen);

        bpf->bpf_stat.bs_capt++;
        bpf_stat.bs_capt++;

        assert(bpf->bpf_sbuf != NULL);
        if (totlen > bpf->bpf_size - bpf->bpf_slen) {
                /*
                 * If the store buffer is full and the hold buffer is not
                 * empty, we cannot swap the two buffers, and so we must drop
                 * the current packet.
                 */
                if (bpf->bpf_hlen > 0) {
                        bpf->bpf_stat.bs_drop++;
                        bpf_stat.bs_drop++;

                        return;
                }

                /*
                 * Rotate the buffers: the hold buffer will now be "full" and
                 * ready to be read - it may not actually be entirely full, but
                 * we could not fit this packet and we are not going to deliver
                 * packets out of order..
                 */
                bpfdev_rotate(bpf);

                hfull = TRUE;
        } else
                hfull = FALSE;

        /*
         * Retrieve the capture time for the packet.  Ideally this would be
         * done only once per accepted packet, but we do not expect many BPF
         * devices to be receiving the same packets often enough to make that
         * worth it.
         */
        clock_time(&ts);

        /*
         * Copy the packet into the store buffer, including a newly generated
         * header.  Zero any padding areas, even if strictly not necessary.
         */
        memset(&bh, 0, sizeof(bh));
        bh.bh_tstamp.tv_sec = ts.tv_sec;
        bh.bh_tstamp.tv_usec = ts.tv_nsec / 1000;
        bh.bh_caplen = caplen;
        bh.bh_datalen = pbuf->tot_len;
        bh.bh_hdrlen = hdrlen;

        assert(bpf->bpf_sbuf != NULL);
        off = bpf->bpf_slen;

        memcpy(&bpf->bpf_sbuf[off], &bh, sizeof(bh));
        if (hdrlen > sizeof(bh))
                memset(&bpf->bpf_sbuf[off + sizeof(bh)], 0,
                    hdrlen - sizeof(bh));
        off += hdrlen;

        for (pptr = pbuf; pptr != NULL && caplen > 0; pptr = pptr->next) {
                chunk = pptr->len;
                if (chunk > caplen)
                        chunk = caplen;

                memcpy(&bpf->bpf_sbuf[off], pptr->payload, chunk);

                off += chunk;
                caplen -= chunk;
        }

        assert(off <= bpf->bpf_slen + totlen);
        if (bpf->bpf_slen + totlen > off)
                memset(&bpf->bpf_sbuf[off], 0, bpf->bpf_slen + totlen - off);

        bpf->bpf_slen += totlen;

        /*
         * Edge case: if the hold buffer is empty and the store buffer is now
         * exactly full, rotate buffers so that the packets can be read
         * immediately, without waiting for the next packet to cause rotation.
         */
        if (bpf->bpf_hlen == 0 && bpf->bpf_slen == bpf->bpf_size) {
                bpfdev_rotate(bpf);

                hfull = TRUE;
        }

        /*
         * If the hold buffer is now full, or if immediate mode is enabled,
         * then we now have data to deliver to userland.  See if we can wake up
         * any read or select call (either but not both here).
         */
        if (hfull || (bpf->bpf_flags & BPFF_IMMEDIATE)) {
                if (bpf->bpf_read.br_endpt != NONE)
                        bpfdev_resume_read(bpf, FALSE /*is_timeout*/);
                else
                        bpfdev_resume_select(bpf);
        }
}

/*
 * Process an outgoing packet on the interface to which the given BPF device is
 * attached.  If the BPF device is configured to capture outgoing packets as
 * well, attempt to capture the packet as per bpfdev_input().
 */
void
bpfdev_output(struct bpfdev_link * bpfl, const struct pbuf * pbuf)
{
        struct bpfdev *bpf = (struct bpfdev *)bpfl;

        if (bpf->bpf_flags & BPFF_SEESENT)
                bpfdev_input(bpfl, pbuf);
}

/*
 * Fill the given 'bde' structure with information about BPF device 'bpf'.
 */
static void
bpfdev_get_info(struct bpf_d_ext * bde, const struct bpfdev * bpf)
{

        bde->bde_bufsize = bpf->bpf_size;
        bde->bde_promisc = !!(bpf->bpf_flags & BPFF_PROMISC);
        bde->bde_state = BPF_IDLE;
        bde->bde_immediate = !!(bpf->bpf_flags & BPFF_IMMEDIATE);
        bde->bde_hdrcmplt = !!(bpf->bpf_flags & BPFF_HDRCMPLT);
        bde->bde_seesent = !!(bpf->bpf_flags & BPFF_SEESENT);
        /*
         * NetBSD updates the process ID upon device open, close, ioctl, and
         * poll.  From those, only open and ioctl make sense for us.  Sadly
         * there is no way to indicate "no known PID" to netstat(1), so we
         * cannot even save just the endpoint and look up the corresponding PID
         * later, since the user process may be gone by then.
         */
        bde->bde_pid = bpf->bpf_pid;
        bde->bde_rcount = bpf->bpf_stat.bs_recv;
        bde->bde_dcount = bpf->bpf_stat.bs_drop;
        bde->bde_ccount = bpf->bpf_stat.bs_capt;
        if (bpf->bpf_ifdev != NULL)
                strlcpy(bde->bde_ifname, ifdev_get_name(bpf->bpf_ifdev),
                    sizeof(bde->bde_ifname));
}

/*
 * Obtain statistics about open BPF devices ("peers").  This node may be
 * accessed by the superuser only.  Used by netstat(1).
 */
static ssize_t
bpfdev_peers(struct rmib_call * call, struct rmib_node * node __unused,
        struct rmib_oldp * oldp, struct rmib_newp * newp __unused)
{
        struct bpfdev *bpf;
        struct bpf_d_ext bde;
        unsigned int slot;
        ssize_t off;
        int r, size, max;

        if (!(call->call_flags & RMIB_FLAG_AUTH))
                return EPERM;

        if (call->call_namelen != 2)
                return EINVAL;

        size = call->call_name[0];
        if (size < 0 || (size_t)size > sizeof(bde))
                return EINVAL;
        if (size == 0)
                size = sizeof(bde);
        max = call->call_name[1];

        off = 0;

        for (slot = 0; slot < __arraycount(bpf_array); slot++) {
                bpf = &bpf_array[slot];

                if (!(bpf->bpf_flags & BPFF_IN_USE))
                        continue;

                if (rmib_inrange(oldp, off)) {
                        memset(&bde, 0, sizeof(bde));

                        bpfdev_get_info(&bde, bpf);

                        if ((r = rmib_copyout(oldp, off, &bde, size)) < 0)
                                return r;
                }

                off += sizeof(bde);
                if (max > 0 && --max == 0)
                        break;
        }

        /* No slack needed: netstat(1) resizes its buffer as needed. */
        return off;
}

static const struct chardriver bpfdev_tab = {
        .cdr_open               = bpfdev_open,
        .cdr_close              = bpfdev_close,
        .cdr_read               = bpfdev_read,
        .cdr_write              = bpfdev_write,
        .cdr_ioctl              = bpfdev_ioctl,
        .cdr_cancel             = bpfdev_cancel,
        .cdr_select             = bpfdev_select
};

/*
 * Process a character driver request.  Since the LWIP service offers character
 * devices for BPF only, it must be a request for a BPF device.
 */
void
bpfdev_process(message * m_ptr, int ipc_status)
{

        chardriver_process(&bpfdev_tab, m_ptr, ipc_status);
}