/* $NetBSD: bpf.c,v 1.159 2010/12/08 17:10:13 pooka Exp $ */ /* * 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. * 3. 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. * * @(#)bpf.c 8.4 (Berkeley) 1/9/95 * static char rcsid[] = * "Header: bpf.c,v 1.67 96/09/26 22:00:52 leres Exp "; */ #include __KERNEL_RCSID(0, "$NetBSD: bpf.c,v 1.159 2010/12/08 17:10:13 pooka Exp $"); #if defined(_KERNEL_OPT) #include "opt_bpf.h" #include "sl.h" #include "strip.h" #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifndef BPF_BUFSIZE /* * 4096 is too small for FDDI frames. 8192 is too small for gigabit Ethernet * jumbos (circa 9k), ATM, or Intel gig/10gig ethernet jumbos (16k). */ # define BPF_BUFSIZE 32768 #endif #define PRINET 26 /* interruptible */ /* * The default read buffer size, and limit for BIOCSBLEN, is sysctl'able. * XXX the default values should be computed dynamically based * on available memory size and available mbuf clusters. */ int bpf_bufsize = BPF_BUFSIZE; int bpf_maxbufsize = BPF_DFLTBUFSIZE; /* XXX set dynamically, see above */ /* * Global BPF statistics returned by net.bpf.stats sysctl. */ struct bpf_stat bpf_gstats; /* * Use a mutex to avoid a race condition between gathering the stats/peers * and opening/closing the device. */ static kmutex_t bpf_mtx; /* * bpf_iflist is the list of interfaces; each corresponds to an ifnet * bpf_dtab holds the descriptors, indexed by minor device # */ struct bpf_if *bpf_iflist; LIST_HEAD(, bpf_d) bpf_list; static int bpf_allocbufs(struct bpf_d *); static void bpf_deliver(struct bpf_if *, void *(*cpfn)(void *, const void *, size_t), void *, u_int, u_int, struct ifnet *); static void bpf_freed(struct bpf_d *); static void bpf_ifname(struct ifnet *, struct ifreq *); static void *bpf_mcpy(void *, const void *, size_t); static int bpf_movein(struct uio *, int, int, struct mbuf **, struct sockaddr *); static void bpf_attachd(struct bpf_d *, struct bpf_if *); static void bpf_detachd(struct bpf_d *); static int bpf_setif(struct bpf_d *, struct ifreq *); static void bpf_timed_out(void *); static inline void bpf_wakeup(struct bpf_d *); static void catchpacket(struct bpf_d *, u_char *, u_int, u_int, void *(*)(void *, const void *, size_t), struct timespec *); static void reset_d(struct bpf_d *); static int bpf_getdltlist(struct bpf_d *, struct bpf_dltlist *); static int bpf_setdlt(struct bpf_d *, u_int); static int bpf_read(struct file *, off_t *, struct uio *, kauth_cred_t, int); static int bpf_write(struct file *, off_t *, struct uio *, kauth_cred_t, int); static int bpf_ioctl(struct file *, u_long, void *); static int bpf_poll(struct file *, int); static int bpf_stat(struct file *, struct stat *); static int bpf_close(struct file *); static int bpf_kqfilter(struct file *, struct knote *); static void bpf_softintr(void *); static const struct fileops bpf_fileops = { .fo_read = bpf_read, .fo_write = bpf_write, .fo_ioctl = bpf_ioctl, .fo_fcntl = fnullop_fcntl, .fo_poll = bpf_poll, .fo_stat = bpf_stat, .fo_close = bpf_close, .fo_kqfilter = bpf_kqfilter, .fo_restart = fnullop_restart, }; dev_type_open(bpfopen); const struct cdevsw bpf_cdevsw = { bpfopen, noclose, noread, nowrite, noioctl, nostop, notty, nopoll, nommap, nokqfilter, D_OTHER }; static int bpf_movein(struct uio *uio, int linktype, int mtu, struct mbuf **mp, struct sockaddr *sockp) { struct mbuf *m; int error; int len; int hlen; int align; /* * Build a sockaddr based on the data link layer type. * We do this at this level because the ethernet header * is copied directly into the data field of the sockaddr. * In the case of SLIP, there is no header and the packet * is forwarded as is. * Also, we are careful to leave room at the front of the mbuf * for the link level header. */ switch (linktype) { case DLT_SLIP: sockp->sa_family = AF_INET; hlen = 0; align = 0; break; case DLT_PPP: sockp->sa_family = AF_UNSPEC; hlen = 0; align = 0; break; case DLT_EN10MB: sockp->sa_family = AF_UNSPEC; /* XXX Would MAXLINKHDR be better? */ /* 6(dst)+6(src)+2(type) */ hlen = sizeof(struct ether_header); align = 2; break; case DLT_ARCNET: sockp->sa_family = AF_UNSPEC; hlen = ARC_HDRLEN; align = 5; break; case DLT_FDDI: sockp->sa_family = AF_LINK; /* XXX 4(FORMAC)+6(dst)+6(src) */ hlen = 16; align = 0; break; case DLT_ECONET: sockp->sa_family = AF_UNSPEC; hlen = 6; align = 2; break; case DLT_NULL: sockp->sa_family = AF_UNSPEC; hlen = 0; align = 0; break; default: return (EIO); } len = uio->uio_resid; /* * If there aren't enough bytes for a link level header or the * packet length exceeds the interface mtu, return an error. */ if (len < hlen || len - hlen > mtu) return (EMSGSIZE); /* * XXX Avoid complicated buffer chaining --- * bail if it won't fit in a single mbuf. * (Take into account possible alignment bytes) */ if ((unsigned)len > MCLBYTES - align) return (EIO); m = m_gethdr(M_WAIT, MT_DATA); m->m_pkthdr.rcvif = 0; m->m_pkthdr.len = len - hlen; if (len > MHLEN - align) { m_clget(m, M_WAIT); if ((m->m_flags & M_EXT) == 0) { error = ENOBUFS; goto bad; } } /* Insure the data is properly aligned */ if (align > 0) { m->m_data += align; m->m_len -= align; } error = uiomove(mtod(m, void *), len, uio); if (error) goto bad; if (hlen != 0) { memcpy(sockp->sa_data, mtod(m, void *), hlen); m->m_data += hlen; /* XXX */ len -= hlen; } m->m_len = len; *mp = m; return (0); bad: m_freem(m); return (error); } /* * Attach file to the bpf interface, i.e. make d listen on bp. * Must be called at splnet. */ static void bpf_attachd(struct bpf_d *d, struct bpf_if *bp) { /* * Point d at bp, and add d to the interface's list of listeners. * Finally, point the driver's bpf cookie at the interface so * it will divert packets to bpf. */ d->bd_bif = bp; d->bd_next = bp->bif_dlist; bp->bif_dlist = d; *bp->bif_driverp = bp; } /* * Detach a file from its interface. */ static void bpf_detachd(struct bpf_d *d) { struct bpf_d **p; struct bpf_if *bp; bp = d->bd_bif; /* * Check if this descriptor had requested promiscuous mode. * If so, turn it off. */ if (d->bd_promisc) { int error; d->bd_promisc = 0; /* * Take device out of promiscuous mode. Since we were * able to enter promiscuous mode, we should be able * to turn it off. But we can get an error if * the interface was configured down, so only panic * if we don't get an unexpected error. */ error = ifpromisc(bp->bif_ifp, 0); if (error && error != EINVAL) panic("%s: ifpromisc failed: %d", __func__, error); } /* Remove d from the interface's descriptor list. */ p = &bp->bif_dlist; while (*p != d) { p = &(*p)->bd_next; if (*p == 0) panic("%s: descriptor not in list", __func__); } *p = (*p)->bd_next; if (bp->bif_dlist == 0) /* * Let the driver know that there are no more listeners. */ *d->bd_bif->bif_driverp = 0; d->bd_bif = 0; } static int doinit(void) { mutex_init(&bpf_mtx, MUTEX_DEFAULT, IPL_NONE); LIST_INIT(&bpf_list); bpf_gstats.bs_recv = 0; bpf_gstats.bs_drop = 0; bpf_gstats.bs_capt = 0; return 0; } /* * bpfilterattach() is called at boot time. */ /* ARGSUSED */ void bpfilterattach(int n) { static ONCE_DECL(control); RUN_ONCE(&control, doinit); } /* * Open ethernet device. Clones. */ /* ARGSUSED */ int bpfopen(dev_t dev, int flag, int mode, struct lwp *l) { struct bpf_d *d; struct file *fp; int error, fd; /* falloc() will use the descriptor for us. */ if ((error = fd_allocfile(&fp, &fd)) != 0) return error; d = malloc(sizeof(*d), M_DEVBUF, M_WAITOK|M_ZERO); d->bd_bufsize = bpf_bufsize; d->bd_seesent = 1; d->bd_feedback = 0; d->bd_pid = l->l_proc->p_pid; getnanotime(&d->bd_btime); d->bd_atime = d->bd_mtime = d->bd_btime; callout_init(&d->bd_callout, 0); selinit(&d->bd_sel); d->bd_sih = softint_establish(SOFTINT_CLOCK, bpf_softintr, d); mutex_enter(&bpf_mtx); LIST_INSERT_HEAD(&bpf_list, d, bd_list); mutex_exit(&bpf_mtx); return fd_clone(fp, fd, flag, &bpf_fileops, d); } /* * Close the descriptor by detaching it from its interface, * deallocating its buffers, and marking it free. */ /* ARGSUSED */ static int bpf_close(struct file *fp) { struct bpf_d *d = fp->f_data; int s; KERNEL_LOCK(1, NULL); /* * Refresh the PID associated with this bpf file. */ d->bd_pid = curproc->p_pid; s = splnet(); if (d->bd_state == BPF_WAITING) callout_stop(&d->bd_callout); d->bd_state = BPF_IDLE; if (d->bd_bif) bpf_detachd(d); splx(s); bpf_freed(d); mutex_enter(&bpf_mtx); LIST_REMOVE(d, bd_list); mutex_exit(&bpf_mtx); callout_destroy(&d->bd_callout); seldestroy(&d->bd_sel); softint_disestablish(d->bd_sih); free(d, M_DEVBUF); fp->f_data = NULL; KERNEL_UNLOCK_ONE(NULL); return (0); } /* * Rotate the packet buffers in descriptor d. Move the store buffer * into the hold slot, and the free buffer into the store slot. * Zero the length of the new store buffer. */ #define ROTATE_BUFFERS(d) \ (d)->bd_hbuf = (d)->bd_sbuf; \ (d)->bd_hlen = (d)->bd_slen; \ (d)->bd_sbuf = (d)->bd_fbuf; \ (d)->bd_slen = 0; \ (d)->bd_fbuf = 0; /* * bpfread - read next chunk of packets from buffers */ static int bpf_read(struct file *fp, off_t *offp, struct uio *uio, kauth_cred_t cred, int flags) { struct bpf_d *d = fp->f_data; int timed_out; int error; int s; getnanotime(&d->bd_atime); /* * Restrict application to use a buffer the same size as * the kernel buffers. */ if (uio->uio_resid != d->bd_bufsize) return (EINVAL); KERNEL_LOCK(1, NULL); s = splnet(); if (d->bd_state == BPF_WAITING) callout_stop(&d->bd_callout); timed_out = (d->bd_state == BPF_TIMED_OUT); d->bd_state = BPF_IDLE; /* * If the hold buffer is empty, then do a timed sleep, which * ends when the timeout expires or when enough packets * have arrived to fill the store buffer. */ while (d->bd_hbuf == 0) { if (fp->f_flag & FNONBLOCK) { if (d->bd_slen == 0) { splx(s); KERNEL_UNLOCK_ONE(NULL); return (EWOULDBLOCK); } ROTATE_BUFFERS(d); break; } if ((d->bd_immediate || timed_out) && d->bd_slen != 0) { /* * A packet(s) either arrived since the previous * read or arrived while we were asleep. * Rotate the buffers and return what's here. */ ROTATE_BUFFERS(d); break; } error = tsleep(d, PRINET|PCATCH, "bpf", d->bd_rtout); if (error == EINTR || error == ERESTART) { splx(s); KERNEL_UNLOCK_ONE(NULL); return (error); } if (error == EWOULDBLOCK) { /* * On a timeout, return what's in the buffer, * which may be nothing. If there is something * in the store buffer, we can rotate the buffers. */ if (d->bd_hbuf) /* * We filled up the buffer in between * getting the timeout and arriving * here, so we don't need to rotate. */ break; if (d->bd_slen == 0) { splx(s); KERNEL_UNLOCK_ONE(NULL); return (0); } ROTATE_BUFFERS(d); break; } if (error != 0) goto done; } /* * At this point, we know we have something in the hold slot. */ splx(s); /* * Move data from hold buffer into user space. * We know the entire buffer is transferred since * we checked above that the read buffer is bpf_bufsize bytes. */ error = uiomove(d->bd_hbuf, d->bd_hlen, uio); s = splnet(); d->bd_fbuf = d->bd_hbuf; d->bd_hbuf = 0; d->bd_hlen = 0; done: splx(s); KERNEL_UNLOCK_ONE(NULL); return (error); } /* * If there are processes sleeping on this descriptor, wake them up. */ static inline void bpf_wakeup(struct bpf_d *d) { wakeup(d); if (d->bd_async) softint_schedule(d->bd_sih); selnotify(&d->bd_sel, 0, 0); } static void bpf_softintr(void *cookie) { struct bpf_d *d; d = cookie; if (d->bd_async) fownsignal(d->bd_pgid, SIGIO, 0, 0, NULL); } static void bpf_timed_out(void *arg) { struct bpf_d *d = arg; int s; s = splnet(); if (d->bd_state == BPF_WAITING) { d->bd_state = BPF_TIMED_OUT; if (d->bd_slen != 0) bpf_wakeup(d); } splx(s); } static int bpf_write(struct file *fp, off_t *offp, struct uio *uio, kauth_cred_t cred, int flags) { struct bpf_d *d = fp->f_data; struct ifnet *ifp; struct mbuf *m, *mc; int error, s; static struct sockaddr_storage dst; m = NULL; /* XXX gcc */ KERNEL_LOCK(1, NULL); if (d->bd_bif == 0) { KERNEL_UNLOCK_ONE(NULL); return (ENXIO); } getnanotime(&d->bd_mtime); ifp = d->bd_bif->bif_ifp; if (uio->uio_resid == 0) { KERNEL_UNLOCK_ONE(NULL); return (0); } error = bpf_movein(uio, (int)d->bd_bif->bif_dlt, ifp->if_mtu, &m, (struct sockaddr *) &dst); if (error) { KERNEL_UNLOCK_ONE(NULL); return (error); } if (m->m_pkthdr.len > ifp->if_mtu) { KERNEL_UNLOCK_ONE(NULL); m_freem(m); return (EMSGSIZE); } if (d->bd_hdrcmplt) dst.ss_family = pseudo_AF_HDRCMPLT; if (d->bd_feedback) { mc = m_dup(m, 0, M_COPYALL, M_NOWAIT); if (mc != NULL) mc->m_pkthdr.rcvif = ifp; /* Set M_PROMISC for outgoing packets to be discarded. */ if (1 /*d->bd_direction == BPF_D_INOUT*/) m->m_flags |= M_PROMISC; } else mc = NULL; s = splsoftnet(); error = (*ifp->if_output)(ifp, m, (struct sockaddr *) &dst, NULL); if (mc != NULL) { if (error == 0) (*ifp->if_input)(ifp, mc); } else m_freem(mc); splx(s); KERNEL_UNLOCK_ONE(NULL); /* * The driver frees the mbuf. */ return (error); } /* * Reset a descriptor by flushing its packet buffer and clearing the * receive and drop counts. Should be called at splnet. */ static void reset_d(struct bpf_d *d) { if (d->bd_hbuf) { /* Free the hold buffer. */ d->bd_fbuf = d->bd_hbuf; d->bd_hbuf = 0; } d->bd_slen = 0; d->bd_hlen = 0; d->bd_rcount = 0; d->bd_dcount = 0; d->bd_ccount = 0; } /* * FIONREAD Check for read packet available. * BIOCGBLEN Get buffer len [for read()]. * BIOCSETF Set ethernet read filter. * BIOCFLUSH Flush read packet buffer. * BIOCPROMISC Put interface into promiscuous mode. * BIOCGDLT Get link layer type. * BIOCGETIF Get interface name. * BIOCSETIF Set interface. * BIOCSRTIMEOUT Set read timeout. * BIOCGRTIMEOUT Get read timeout. * BIOCGSTATS Get packet stats. * BIOCIMMEDIATE Set immediate mode. * BIOCVERSION Get filter language version. * BIOCGHDRCMPLT Get "header already complete" flag. * BIOCSHDRCMPLT Set "header already complete" flag. * BIOCSFEEDBACK Set packet feedback mode. * BIOCGFEEDBACK Get packet feedback mode. * BIOCGSEESENT Get "see sent packets" mode. * BIOCSSEESENT Set "see sent packets" mode. */ /* ARGSUSED */ static int bpf_ioctl(struct file *fp, u_long cmd, void *addr) { struct bpf_d *d = fp->f_data; int s, error = 0; /* * Refresh the PID associated with this bpf file. */ KERNEL_LOCK(1, NULL); d->bd_pid = curproc->p_pid; s = splnet(); if (d->bd_state == BPF_WAITING) callout_stop(&d->bd_callout); d->bd_state = BPF_IDLE; splx(s); switch (cmd) { default: error = EINVAL; break; /* * Check for read packet available. */ case FIONREAD: { int n; s = splnet(); n = d->bd_slen; if (d->bd_hbuf) n += d->bd_hlen; splx(s); *(int *)addr = n; break; } /* * Get buffer len [for read()]. */ case BIOCGBLEN: *(u_int *)addr = d->bd_bufsize; break; /* * Set buffer length. */ case BIOCSBLEN: if (d->bd_bif != 0) error = EINVAL; else { u_int size = *(u_int *)addr; if (size > bpf_maxbufsize) *(u_int *)addr = size = bpf_maxbufsize; else if (size < BPF_MINBUFSIZE) *(u_int *)addr = size = BPF_MINBUFSIZE; d->bd_bufsize = size; } break; /* * Set link layer read filter. */ case BIOCSETF: error = bpf_setf(d, addr); break; /* * Flush read packet buffer. */ case BIOCFLUSH: s = splnet(); reset_d(d); splx(s); break; /* * Put interface into promiscuous mode. */ case BIOCPROMISC: if (d->bd_bif == 0) { /* * No interface attached yet. */ error = EINVAL; break; } s = splnet(); if (d->bd_promisc == 0) { error = ifpromisc(d->bd_bif->bif_ifp, 1); if (error == 0) d->bd_promisc = 1; } splx(s); break; /* * Get device parameters. */ case BIOCGDLT: if (d->bd_bif == 0) error = EINVAL; else *(u_int *)addr = d->bd_bif->bif_dlt; break; /* * Get a list of supported device parameters. */ case BIOCGDLTLIST: if (d->bd_bif == 0) error = EINVAL; else error = bpf_getdltlist(d, addr); break; /* * Set device parameters. */ case BIOCSDLT: if (d->bd_bif == 0) error = EINVAL; else error = bpf_setdlt(d, *(u_int *)addr); break; /* * Set interface name. */ #ifdef OBIOCGETIF case OBIOCGETIF: #endif case BIOCGETIF: if (d->bd_bif == 0) error = EINVAL; else bpf_ifname(d->bd_bif->bif_ifp, addr); break; /* * Set interface. */ #ifdef OBIOCSETIF case OBIOCSETIF: #endif case BIOCSETIF: error = bpf_setif(d, addr); break; /* * Set read timeout. */ case BIOCSRTIMEOUT: { struct timeval *tv = addr; /* Compute number of ticks. */ d->bd_rtout = tv->tv_sec * hz + tv->tv_usec / tick; if ((d->bd_rtout == 0) && (tv->tv_usec != 0)) d->bd_rtout = 1; break; } #ifdef BIOCGORTIMEOUT /* * Get read timeout. */ case BIOCGORTIMEOUT: { struct timeval50 *tv = addr; tv->tv_sec = d->bd_rtout / hz; tv->tv_usec = (d->bd_rtout % hz) * tick; break; } #endif #ifdef BIOCSORTIMEOUT /* * Set read timeout. */ case BIOCSORTIMEOUT: { struct timeval50 *tv = addr; /* Compute number of ticks. */ d->bd_rtout = tv->tv_sec * hz + tv->tv_usec / tick; if ((d->bd_rtout == 0) && (tv->tv_usec != 0)) d->bd_rtout = 1; break; } #endif /* * Get read timeout. */ case BIOCGRTIMEOUT: { struct timeval *tv = addr; tv->tv_sec = d->bd_rtout / hz; tv->tv_usec = (d->bd_rtout % hz) * tick; break; } /* * Get packet stats. */ case BIOCGSTATS: { struct bpf_stat *bs = addr; bs->bs_recv = d->bd_rcount; bs->bs_drop = d->bd_dcount; bs->bs_capt = d->bd_ccount; break; } case BIOCGSTATSOLD: { struct bpf_stat_old *bs = addr; bs->bs_recv = d->bd_rcount; bs->bs_drop = d->bd_dcount; break; } /* * Set immediate mode. */ case BIOCIMMEDIATE: d->bd_immediate = *(u_int *)addr; break; case BIOCVERSION: { struct bpf_version *bv = addr; bv->bv_major = BPF_MAJOR_VERSION; bv->bv_minor = BPF_MINOR_VERSION; break; } case BIOCGHDRCMPLT: /* get "header already complete" flag */ *(u_int *)addr = d->bd_hdrcmplt; break; case BIOCSHDRCMPLT: /* set "header already complete" flag */ d->bd_hdrcmplt = *(u_int *)addr ? 1 : 0; break; /* * Get "see sent packets" flag */ case BIOCGSEESENT: *(u_int *)addr = d->bd_seesent; break; /* * Set "see sent" packets flag */ case BIOCSSEESENT: d->bd_seesent = *(u_int *)addr; break; /* * Set "feed packets from bpf back to input" mode */ case BIOCSFEEDBACK: d->bd_feedback = *(u_int *)addr; break; /* * Get "feed packets from bpf back to input" mode */ case BIOCGFEEDBACK: *(u_int *)addr = d->bd_feedback; break; case FIONBIO: /* Non-blocking I/O */ /* * No need to do anything special as we use IO_NDELAY in * bpfread() as an indication of whether or not to block * the read. */ break; case FIOASYNC: /* Send signal on receive packets */ d->bd_async = *(int *)addr; break; case TIOCSPGRP: /* Process or group to send signals to */ case FIOSETOWN: error = fsetown(&d->bd_pgid, cmd, addr); break; case TIOCGPGRP: case FIOGETOWN: error = fgetown(d->bd_pgid, cmd, addr); break; } KERNEL_UNLOCK_ONE(NULL); return (error); } /* * Set d's packet filter program to fp. If this file already has a filter, * free it and replace it. Returns EINVAL for bogus requests. */ int bpf_setf(struct bpf_d *d, struct bpf_program *fp) { struct bpf_insn *fcode, *old; u_int flen, size; int s; old = d->bd_filter; if (fp->bf_insns == 0) { if (fp->bf_len != 0) return (EINVAL); s = splnet(); d->bd_filter = 0; reset_d(d); splx(s); if (old != 0) free(old, M_DEVBUF); return (0); } flen = fp->bf_len; if (flen > BPF_MAXINSNS) return (EINVAL); size = flen * sizeof(*fp->bf_insns); fcode = malloc(size, M_DEVBUF, M_WAITOK); if (copyin(fp->bf_insns, fcode, size) == 0 && bpf_validate(fcode, (int)flen)) { s = splnet(); d->bd_filter = fcode; reset_d(d); splx(s); if (old != 0) free(old, M_DEVBUF); return (0); } free(fcode, M_DEVBUF); return (EINVAL); } /* * Detach a file from its current interface (if attached at all) and attach * to the interface indicated by the name stored in ifr. * Return an errno or 0. */ static int bpf_setif(struct bpf_d *d, struct ifreq *ifr) { struct bpf_if *bp; char *cp; int unit_seen, i, s, error; /* * Make sure the provided name has a unit number, and default * it to '0' if not specified. * XXX This is ugly ... do this differently? */ unit_seen = 0; cp = ifr->ifr_name; cp[sizeof(ifr->ifr_name) - 1] = '\0'; /* sanity */ while (*cp++) if (*cp >= '0' && *cp <= '9') unit_seen = 1; if (!unit_seen) { /* Make sure to leave room for the '\0'. */ for (i = 0; i < (IFNAMSIZ - 1); ++i) { if ((ifr->ifr_name[i] >= 'a' && ifr->ifr_name[i] <= 'z') || (ifr->ifr_name[i] >= 'A' && ifr->ifr_name[i] <= 'Z')) continue; ifr->ifr_name[i] = '0'; } } /* * Look through attached interfaces for the named one. */ for (bp = bpf_iflist; bp != 0; bp = bp->bif_next) { struct ifnet *ifp = bp->bif_ifp; if (ifp == 0 || strcmp(ifp->if_xname, ifr->ifr_name) != 0) continue; /* skip additional entry */ if (bp->bif_driverp != &ifp->if_bpf) continue; /* * We found the requested interface. * Allocate the packet buffers if we need to. * If we're already attached to requested interface, * just flush the buffer. */ if (d->bd_sbuf == 0) { error = bpf_allocbufs(d); if (error != 0) return (error); } s = splnet(); if (bp != d->bd_bif) { if (d->bd_bif) /* * Detach if attached to something else. */ bpf_detachd(d); bpf_attachd(d, bp); } reset_d(d); splx(s); return (0); } /* Not found. */ return (ENXIO); } /* * Copy the interface name to the ifreq. */ static void bpf_ifname(struct ifnet *ifp, struct ifreq *ifr) { memcpy(ifr->ifr_name, ifp->if_xname, IFNAMSIZ); } static int bpf_stat(struct file *fp, struct stat *st) { struct bpf_d *d = fp->f_data; (void)memset(st, 0, sizeof(*st)); KERNEL_LOCK(1, NULL); st->st_dev = makedev(cdevsw_lookup_major(&bpf_cdevsw), d->bd_pid); st->st_atimespec = d->bd_atime; st->st_mtimespec = d->bd_mtime; st->st_ctimespec = st->st_birthtimespec = d->bd_btime; st->st_uid = kauth_cred_geteuid(fp->f_cred); st->st_gid = kauth_cred_getegid(fp->f_cred); KERNEL_UNLOCK_ONE(NULL); return 0; } /* * Support for poll() system call * * Return true iff the specific operation will not block indefinitely - with * the assumption that it is safe to positively acknowledge a request for the * ability to write to the BPF device. * Otherwise, return false but make a note that a selnotify() must be done. */ static int bpf_poll(struct file *fp, int events) { struct bpf_d *d = fp->f_data; int s = splnet(); int revents; /* * Refresh the PID associated with this bpf file. */ KERNEL_LOCK(1, NULL); d->bd_pid = curproc->p_pid; revents = events & (POLLOUT | POLLWRNORM); if (events & (POLLIN | POLLRDNORM)) { /* * An imitation of the FIONREAD ioctl code. */ if (d->bd_hlen != 0 || ((d->bd_immediate || d->bd_state == BPF_TIMED_OUT) && d->bd_slen != 0)) { revents |= events & (POLLIN | POLLRDNORM); } else { selrecord(curlwp, &d->bd_sel); /* Start the read timeout if necessary */ if (d->bd_rtout > 0 && d->bd_state == BPF_IDLE) { callout_reset(&d->bd_callout, d->bd_rtout, bpf_timed_out, d); d->bd_state = BPF_WAITING; } } } KERNEL_UNLOCK_ONE(NULL); splx(s); return (revents); } static void filt_bpfrdetach(struct knote *kn) { struct bpf_d *d = kn->kn_hook; int s; KERNEL_LOCK(1, NULL); s = splnet(); SLIST_REMOVE(&d->bd_sel.sel_klist, kn, knote, kn_selnext); splx(s); KERNEL_UNLOCK_ONE(NULL); } static int filt_bpfread(struct knote *kn, long hint) { struct bpf_d *d = kn->kn_hook; int rv; KERNEL_LOCK(1, NULL); kn->kn_data = d->bd_hlen; if (d->bd_immediate) kn->kn_data += d->bd_slen; rv = (kn->kn_data > 0); KERNEL_UNLOCK_ONE(NULL); return rv; } static const struct filterops bpfread_filtops = { 1, NULL, filt_bpfrdetach, filt_bpfread }; static int bpf_kqfilter(struct file *fp, struct knote *kn) { struct bpf_d *d = fp->f_data; struct klist *klist; int s; KERNEL_LOCK(1, NULL); switch (kn->kn_filter) { case EVFILT_READ: klist = &d->bd_sel.sel_klist; kn->kn_fop = &bpfread_filtops; break; default: KERNEL_UNLOCK_ONE(NULL); return (EINVAL); } kn->kn_hook = d; s = splnet(); SLIST_INSERT_HEAD(klist, kn, kn_selnext); splx(s); KERNEL_UNLOCK_ONE(NULL); return (0); } /* * Incoming linkage from device drivers. Process the packet pkt, of length * pktlen, which is stored in a contiguous buffer. The packet is parsed * by each process' filter, and if accepted, stashed into the corresponding * buffer. */ static void _bpf_tap(struct bpf_if *bp, u_char *pkt, u_int pktlen) { struct bpf_d *d; u_int slen; struct timespec ts; int gottime=0; /* * Note that the ipl does not have to be raised at this point. * The only problem that could arise here is that if two different * interfaces shared any data. This is not the case. */ for (d = bp->bif_dlist; d != 0; d = d->bd_next) { ++d->bd_rcount; ++bpf_gstats.bs_recv; slen = bpf_filter(d->bd_filter, pkt, pktlen, pktlen); if (slen != 0) { if (!gottime) { nanotime(&ts); gottime = 1; } catchpacket(d, pkt, pktlen, slen, memcpy, &ts); } } } /* * Copy data from an mbuf chain into a buffer. This code is derived * from m_copydata in sys/uipc_mbuf.c. */ static void * bpf_mcpy(void *dst_arg, const void *src_arg, size_t len) { const struct mbuf *m; u_int count; u_char *dst; m = src_arg; dst = dst_arg; while (len > 0) { if (m == NULL) panic("bpf_mcpy"); count = min(m->m_len, len); memcpy(dst, mtod(m, const void *), count); m = m->m_next; dst += count; len -= count; } return dst_arg; } /* * Dispatch a packet to all the listeners on interface bp. * * marg pointer to the packet, either a data buffer or an mbuf chain * buflen buffer length, if marg is a data buffer * cpfn a function that can copy marg into the listener's buffer * pktlen length of the packet * rcvif either NULL or the interface the packet came in on. */ static inline void bpf_deliver(struct bpf_if *bp, void *(*cpfn)(void *, const void *, size_t), void *marg, u_int pktlen, u_int buflen, struct ifnet *rcvif) { u_int slen; struct bpf_d *d; struct timespec ts; int gottime = 0; for (d = bp->bif_dlist; d != 0; d = d->bd_next) { if (!d->bd_seesent && (rcvif == NULL)) continue; ++d->bd_rcount; ++bpf_gstats.bs_recv; slen = bpf_filter(d->bd_filter, marg, pktlen, buflen); if (slen != 0) { if(!gottime) { nanotime(&ts); gottime = 1; } catchpacket(d, marg, pktlen, slen, cpfn, &ts); } } } /* * Incoming linkage from device drivers, when the head of the packet is in * a buffer, and the tail is in an mbuf chain. */ static void _bpf_mtap2(struct bpf_if *bp, void *data, u_int dlen, struct mbuf *m) { u_int pktlen; struct mbuf mb; /* Skip outgoing duplicate packets. */ if ((m->m_flags & M_PROMISC) != 0 && m->m_pkthdr.rcvif == NULL) { m->m_flags &= ~M_PROMISC; return; } pktlen = m_length(m) + dlen; /* * Craft on-stack mbuf suitable for passing to bpf_filter. * Note that we cut corners here; we only setup what's * absolutely needed--this mbuf should never go anywhere else. */ (void)memset(&mb, 0, sizeof(mb)); mb.m_next = m; mb.m_data = data; mb.m_len = dlen; bpf_deliver(bp, bpf_mcpy, &mb, pktlen, 0, m->m_pkthdr.rcvif); } /* * Incoming linkage from device drivers, when packet is in an mbuf chain. */ static void _bpf_mtap(struct bpf_if *bp, struct mbuf *m) { void *(*cpfn)(void *, const void *, size_t); u_int pktlen, buflen; void *marg; /* Skip outgoing duplicate packets. */ if ((m->m_flags & M_PROMISC) != 0 && m->m_pkthdr.rcvif == NULL) { m->m_flags &= ~M_PROMISC; return; } pktlen = m_length(m); if (pktlen == m->m_len) { cpfn = (void *)memcpy; marg = mtod(m, void *); buflen = pktlen; } else { cpfn = bpf_mcpy; marg = m; buflen = 0; } bpf_deliver(bp, cpfn, marg, pktlen, buflen, m->m_pkthdr.rcvif); } /* * We need to prepend the address family as * a four byte field. Cons up a dummy header * to pacify bpf. This is safe because bpf * will only read from the mbuf (i.e., it won't * try to free it or keep a pointer a to it). */ static void _bpf_mtap_af(struct bpf_if *bp, uint32_t af, struct mbuf *m) { struct mbuf m0; m0.m_flags = 0; m0.m_next = m; m0.m_len = 4; m0.m_data = (char *)⁡ _bpf_mtap(bp, &m0); } /* * Put the SLIP pseudo-"link header" in place. * Note this M_PREPEND() should never fail, * swince we know we always have enough space * in the input buffer. */ static void _bpf_mtap_sl_in(struct bpf_if *bp, u_char *chdr, struct mbuf **m) { int s; u_char *hp; M_PREPEND(*m, SLIP_HDRLEN, M_DONTWAIT); if (*m == NULL) return; hp = mtod(*m, u_char *); hp[SLX_DIR] = SLIPDIR_IN; (void)memcpy(&hp[SLX_CHDR], chdr, CHDR_LEN); s = splnet(); _bpf_mtap(bp, *m); splx(s); m_adj(*m, SLIP_HDRLEN); } /* * Put the SLIP pseudo-"link header" in * place. The compressed header is now * at the beginning of the mbuf. */ static void _bpf_mtap_sl_out(struct bpf_if *bp, u_char *chdr, struct mbuf *m) { struct mbuf m0; u_char *hp; int s; m0.m_flags = 0; m0.m_next = m; m0.m_data = m0.m_dat; m0.m_len = SLIP_HDRLEN; hp = mtod(&m0, u_char *); hp[SLX_DIR] = SLIPDIR_OUT; (void)memcpy(&hp[SLX_CHDR], chdr, CHDR_LEN); s = splnet(); _bpf_mtap(bp, &m0); splx(s); m_freem(m); } /* * Move the packet data from interface memory (pkt) into the * store buffer. Return 1 if it's time to wakeup a listener (buffer full), * otherwise 0. "copy" is the routine called to do the actual data * transfer. memcpy is passed in to copy contiguous chunks, while * bpf_mcpy is passed in to copy mbuf chains. In the latter case, * pkt is really an mbuf. */ static void catchpacket(struct bpf_d *d, u_char *pkt, u_int pktlen, u_int snaplen, void *(*cpfn)(void *, const void *, size_t), struct timespec *ts) { struct bpf_hdr *hp; int totlen, curlen; int hdrlen = d->bd_bif->bif_hdrlen; int do_wakeup = 0; ++d->bd_ccount; ++bpf_gstats.bs_capt; /* * Figure out how many bytes to move. If the packet is * greater or equal to the snapshot length, transfer that * much. Otherwise, transfer the whole packet (unless * we hit the buffer size limit). */ totlen = hdrlen + min(snaplen, pktlen); if (totlen > d->bd_bufsize) totlen = d->bd_bufsize; /* * Round up the end of the previous packet to the next longword. */ curlen = BPF_WORDALIGN(d->bd_slen); if (curlen + totlen > d->bd_bufsize) { /* * This packet will overflow the storage buffer. * Rotate the buffers if we can, then wakeup any * pending reads. */ if (d->bd_fbuf == 0) { /* * We haven't completed the previous read yet, * so drop the packet. */ ++d->bd_dcount; ++bpf_gstats.bs_drop; return; } ROTATE_BUFFERS(d); do_wakeup = 1; curlen = 0; } else if (d->bd_immediate || d->bd_state == BPF_TIMED_OUT) { /* * Immediate mode is set, or the read timeout has * already expired during a select call. A packet * arrived, so the reader should be woken up. */ do_wakeup = 1; } /* * Append the bpf header. */ hp = (struct bpf_hdr *)((char *)d->bd_sbuf + curlen); hp->bh_tstamp.tv_sec = ts->tv_sec; hp->bh_tstamp.tv_usec = ts->tv_nsec / 1000; hp->bh_datalen = pktlen; hp->bh_hdrlen = hdrlen; /* * Copy the packet data into the store buffer and update its length. */ (*cpfn)((u_char *)hp + hdrlen, pkt, (hp->bh_caplen = totlen - hdrlen)); d->bd_slen = curlen + totlen; /* * Call bpf_wakeup after bd_slen has been updated so that kevent(2) * will cause filt_bpfread() to be called with it adjusted. */ if (do_wakeup) bpf_wakeup(d); } /* * Initialize all nonzero fields of a descriptor. */ static int bpf_allocbufs(struct bpf_d *d) { d->bd_fbuf = malloc(d->bd_bufsize, M_DEVBUF, M_NOWAIT); if (!d->bd_fbuf) return (ENOBUFS); d->bd_sbuf = malloc(d->bd_bufsize, M_DEVBUF, M_NOWAIT); if (!d->bd_sbuf) { free(d->bd_fbuf, M_DEVBUF); return (ENOBUFS); } d->bd_slen = 0; d->bd_hlen = 0; return (0); } /* * Free buffers currently in use by a descriptor. * Called on close. */ static void bpf_freed(struct bpf_d *d) { /* * We don't need to lock out interrupts since this descriptor has * been detached from its interface and it yet hasn't been marked * free. */ if (d->bd_sbuf != 0) { free(d->bd_sbuf, M_DEVBUF); if (d->bd_hbuf != 0) free(d->bd_hbuf, M_DEVBUF); if (d->bd_fbuf != 0) free(d->bd_fbuf, M_DEVBUF); } if (d->bd_filter) free(d->bd_filter, M_DEVBUF); } /* * Attach an interface to bpf. dlt is the link layer type; * hdrlen is the fixed size of the link header for the specified dlt * (variable length headers not yet supported). */ static void _bpfattach(struct ifnet *ifp, u_int dlt, u_int hdrlen, struct bpf_if **driverp) { struct bpf_if *bp; bp = malloc(sizeof(*bp), M_DEVBUF, M_DONTWAIT); if (bp == 0) panic("bpfattach"); bp->bif_dlist = 0; bp->bif_driverp = driverp; bp->bif_ifp = ifp; bp->bif_dlt = dlt; bp->bif_next = bpf_iflist; bpf_iflist = bp; *bp->bif_driverp = 0; /* * Compute the length of the bpf header. This is not necessarily * equal to SIZEOF_BPF_HDR because we want to insert spacing such * that the network layer header begins on a longword boundary (for * performance reasons and to alleviate alignment restrictions). */ bp->bif_hdrlen = BPF_WORDALIGN(hdrlen + SIZEOF_BPF_HDR) - hdrlen; #if 0 printf("bpf: %s attached\n", ifp->if_xname); #endif } /* * Remove an interface from bpf. */ static void _bpfdetach(struct ifnet *ifp) { struct bpf_if *bp, **pbp; struct bpf_d *d; int s; /* Nuke the vnodes for any open instances */ LIST_FOREACH(d, &bpf_list, bd_list) { if (d->bd_bif != NULL && d->bd_bif->bif_ifp == ifp) { /* * Detach the descriptor from an interface now. * It will be free'ed later by close routine. */ s = splnet(); d->bd_promisc = 0; /* we can't touch device. */ bpf_detachd(d); splx(s); } } again: for (bp = bpf_iflist, pbp = &bpf_iflist; bp != NULL; pbp = &bp->bif_next, bp = bp->bif_next) { if (bp->bif_ifp == ifp) { *pbp = bp->bif_next; free(bp, M_DEVBUF); goto again; } } } /* * Change the data link type of a interface. */ static void _bpf_change_type(struct ifnet *ifp, u_int dlt, u_int hdrlen) { struct bpf_if *bp; for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) { if (bp->bif_driverp == &ifp->if_bpf) break; } if (bp == NULL) panic("bpf_change_type"); bp->bif_dlt = dlt; /* * Compute the length of the bpf header. This is not necessarily * equal to SIZEOF_BPF_HDR because we want to insert spacing such * that the network layer header begins on a longword boundary (for * performance reasons and to alleviate alignment restrictions). */ bp->bif_hdrlen = BPF_WORDALIGN(hdrlen + SIZEOF_BPF_HDR) - hdrlen; } /* * Get a list of available data link type of the interface. */ static int bpf_getdltlist(struct bpf_d *d, struct bpf_dltlist *bfl) { int n, error; struct ifnet *ifp; struct bpf_if *bp; ifp = d->bd_bif->bif_ifp; n = 0; error = 0; for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) { if (bp->bif_ifp != ifp) continue; if (bfl->bfl_list != NULL) { if (n >= bfl->bfl_len) return ENOMEM; error = copyout(&bp->bif_dlt, bfl->bfl_list + n, sizeof(u_int)); } n++; } bfl->bfl_len = n; return error; } /* * Set the data link type of a BPF instance. */ static int bpf_setdlt(struct bpf_d *d, u_int dlt) { int s, error, opromisc; struct ifnet *ifp; struct bpf_if *bp; if (d->bd_bif->bif_dlt == dlt) return 0; ifp = d->bd_bif->bif_ifp; for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) { if (bp->bif_ifp == ifp && bp->bif_dlt == dlt) break; } if (bp == NULL) return EINVAL; s = splnet(); opromisc = d->bd_promisc; bpf_detachd(d); bpf_attachd(d, bp); reset_d(d); if (opromisc) { error = ifpromisc(bp->bif_ifp, 1); if (error) printf("%s: bpf_setdlt: ifpromisc failed (%d)\n", bp->bif_ifp->if_xname, error); else d->bd_promisc = 1; } splx(s); return 0; } static int sysctl_net_bpf_maxbufsize(SYSCTLFN_ARGS) { int newsize, error; struct sysctlnode node; node = *rnode; node.sysctl_data = &newsize; newsize = bpf_maxbufsize; error = sysctl_lookup(SYSCTLFN_CALL(&node)); if (error || newp == NULL) return (error); if (newsize < BPF_MINBUFSIZE || newsize > BPF_MAXBUFSIZE) return (EINVAL); bpf_maxbufsize = newsize; return (0); } static int sysctl_net_bpf_peers(SYSCTLFN_ARGS) { int error, elem_count; struct bpf_d *dp; struct bpf_d_ext dpe; size_t len, needed, elem_size, out_size; char *sp; if (namelen == 1 && name[0] == CTL_QUERY) return (sysctl_query(SYSCTLFN_CALL(rnode))); if (namelen != 2) return (EINVAL); /* BPF peers is privileged information. */ error = kauth_authorize_network(l->l_cred, KAUTH_NETWORK_INTERFACE, KAUTH_REQ_NETWORK_INTERFACE_GETPRIV, NULL, NULL, NULL); if (error) return (EPERM); len = (oldp != NULL) ? *oldlenp : 0; sp = oldp; elem_size = name[0]; elem_count = name[1]; out_size = MIN(sizeof(dpe), elem_size); needed = 0; if (elem_size < 1 || elem_count < 0) return (EINVAL); mutex_enter(&bpf_mtx); LIST_FOREACH(dp, &bpf_list, bd_list) { if (len >= elem_size && elem_count > 0) { #define BPF_EXT(field) dpe.bde_ ## field = dp->bd_ ## field BPF_EXT(bufsize); BPF_EXT(promisc); BPF_EXT(promisc); BPF_EXT(state); BPF_EXT(immediate); BPF_EXT(hdrcmplt); BPF_EXT(seesent); BPF_EXT(pid); BPF_EXT(rcount); BPF_EXT(dcount); BPF_EXT(ccount); #undef BPF_EXT if (dp->bd_bif) (void)strlcpy(dpe.bde_ifname, dp->bd_bif->bif_ifp->if_xname, IFNAMSIZ - 1); else dpe.bde_ifname[0] = '\0'; error = copyout(&dpe, sp, out_size); if (error) break; sp += elem_size; len -= elem_size; } needed += elem_size; if (elem_count > 0 && elem_count != INT_MAX) elem_count--; } mutex_exit(&bpf_mtx); *oldlenp = needed; return (error); } static struct sysctllog *bpf_sysctllog; static void sysctl_net_bpf_setup(void) { const struct sysctlnode *node; sysctl_createv(&bpf_sysctllog, 0, NULL, NULL, CTLFLAG_PERMANENT, CTLTYPE_NODE, "net", NULL, NULL, 0, NULL, 0, CTL_NET, CTL_EOL); node = NULL; sysctl_createv(&bpf_sysctllog, 0, NULL, &node, CTLFLAG_PERMANENT, CTLTYPE_NODE, "bpf", SYSCTL_DESCR("BPF options"), NULL, 0, NULL, 0, CTL_NET, CTL_CREATE, CTL_EOL); if (node != NULL) { sysctl_createv(&bpf_sysctllog, 0, NULL, NULL, CTLFLAG_PERMANENT|CTLFLAG_READWRITE, CTLTYPE_INT, "maxbufsize", SYSCTL_DESCR("Maximum size for data capture buffer"), sysctl_net_bpf_maxbufsize, 0, &bpf_maxbufsize, 0, CTL_NET, node->sysctl_num, CTL_CREATE, CTL_EOL); sysctl_createv(&bpf_sysctllog, 0, NULL, NULL, CTLFLAG_PERMANENT, CTLTYPE_STRUCT, "stats", SYSCTL_DESCR("BPF stats"), NULL, 0, &bpf_gstats, sizeof(bpf_gstats), CTL_NET, node->sysctl_num, CTL_CREATE, CTL_EOL); sysctl_createv(&bpf_sysctllog, 0, NULL, NULL, CTLFLAG_PERMANENT, CTLTYPE_STRUCT, "peers", SYSCTL_DESCR("BPF peers"), sysctl_net_bpf_peers, 0, NULL, 0, CTL_NET, node->sysctl_num, CTL_CREATE, CTL_EOL); } } struct bpf_ops bpf_ops_kernel = { .bpf_attach = _bpfattach, .bpf_detach = _bpfdetach, .bpf_change_type = _bpf_change_type, .bpf_tap = _bpf_tap, .bpf_mtap = _bpf_mtap, .bpf_mtap2 = _bpf_mtap2, .bpf_mtap_af = _bpf_mtap_af, .bpf_mtap_sl_in = _bpf_mtap_sl_in, .bpf_mtap_sl_out = _bpf_mtap_sl_out, }; MODULE(MODULE_CLASS_DRIVER, bpf, NULL); static int bpf_modcmd(modcmd_t cmd, void *arg) { devmajor_t bmajor, cmajor; int error; bmajor = cmajor = NODEVMAJOR; switch (cmd) { case MODULE_CMD_INIT: bpfilterattach(0); error = devsw_attach("bpf", NULL, &bmajor, &bpf_cdevsw, &cmajor); if (error == EEXIST) error = 0; /* maybe built-in ... improve eventually */ if (error) break; bpf_ops_handover_enter(&bpf_ops_kernel); atomic_swap_ptr(&bpf_ops, &bpf_ops_kernel); bpf_ops_handover_exit(); sysctl_net_bpf_setup(); break; case MODULE_CMD_FINI: /* * While there is no reference counting for bpf callers, * unload could at least in theory be done similarly to * system call disestablishment. This should even be * a little simpler: * * 1) replace op vector with stubs * 2) post update to all cpus with xc * 3) check that nobody is in bpf anymore * (it's doubtful we'd want something like l_sysent, * but we could do something like *signed* percpu * counters. if the sum is 0, we're good). * 4) if fail, unroll changes * * NOTE: change won't be atomic to the outside. some * packets may be not captured even if unload is * not succesful. I think packet capture not working * is a perfectly logical consequence of trying to * disable packet capture. */ error = EOPNOTSUPP; /* insert sysctl teardown */ break; default: error = ENOTTY; break; } return error; }