On 11/01/18(Thu) 11:58, David Gwynne wrote:
> im sending this out more as a backup than a serious diff.

I love this.  It's one of the steps to be able to use bpf(4) for USB.

Is there an easy way to also remove the mbuf requirement?  For example
I'd like to call bpf_mtap() or similar in usb_transfer_complete().

> this tweaks bpf so it can be used by subsystems, not just interfaces.
> this is done by making bpf store and use names (eg, "pf" and "em0")
> instead of just interfaces. interfaces get some special handling
> so you can't bpfwrite or enable ifpromisc unless bif_ifp is set.
> 
> an example use of this is attaching bpf to pf. you can see all the
> packets handed to pf_test with this diff and tcpdump -ni pf.
> 
> Index: bpf.c
> ===================================================================
> RCS file: /cvs/src/sys/net/bpf.c,v
> retrieving revision 1.165
> diff -u -p -r1.165 bpf.c
> --- bpf.c     30 Dec 2017 23:08:29 -0000      1.165
> +++ bpf.c     10 Jan 2018 07:27:45 -0000
> @@ -93,7 +93,7 @@ struct bpf_if       *bpf_iflist;
>  LIST_HEAD(, bpf_d) bpf_d_list;
>  
>  int  bpf_allocbufs(struct bpf_d *);
> -void bpf_ifname(struct ifnet *, struct ifreq *);
> +void bpf_ifname(struct bpf_if*, struct ifreq *);
>  int  _bpf_mtap(caddr_t, const struct mbuf *, u_int,
>           void (*)(const void *, void *, size_t));
>  void bpf_mcopy(const void *, void *, size_t);
> @@ -320,6 +320,8 @@ bpf_detachd(struct bpf_d *d)
>       if (d->bd_promisc) {
>               int error;
>  
> +             KASSERT(bp->bif_ifp != NULL);
> +
>               d->bd_promisc = 0;
>  
>               bpf_get(d);
> @@ -593,7 +595,7 @@ bpfwrite(dev_t dev, struct uio *uio, int
>       bpf_get(d);
>       ifp = d->bd_bif->bif_ifp;
>  
> -     if ((ifp->if_flags & IFF_UP) == 0) {
> +     if (ifp == NULL || (ifp->if_flags & IFF_UP) == 0) {
>               error = ENETDOWN;
>               goto out;
>       }
> @@ -789,7 +791,7 @@ bpfioctl(dev_t dev, u_long cmd, caddr_t 
>                        * No interface attached yet.
>                        */
>                       error = EINVAL;
> -             } else {
> +             } else if (d->bd_bif->bif_ifp != NULL) { 
>                       if (d->bd_promisc == 0) {
>                               MUTEX_ASSERT_UNLOCKED(&d->bd_mtx);
>                               error = ifpromisc(d->bd_bif->bif_ifp, 1);
> @@ -839,7 +841,7 @@ bpfioctl(dev_t dev, u_long cmd, caddr_t 
>               if (d->bd_bif == NULL)
>                       error = EINVAL;
>               else
> -                     bpf_ifname(d->bd_bif->bif_ifp, (struct ifreq *)addr);
> +                     bpf_ifname(d->bd_bif, (struct ifreq *)addr);
>               break;
>  
>       /*
> @@ -1049,10 +1051,7 @@ bpf_setif(struct bpf_d *d, struct ifreq 
>        * Look through attached interfaces for the named one.
>        */
>       for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
> -             struct ifnet *ifp = bp->bif_ifp;
> -
> -             if (ifp == NULL ||
> -                 strcmp(ifp->if_xname, ifr->ifr_name) != 0)
> +             if (strcmp(bp->bif_name, ifr->ifr_name) != 0)
>                       continue;
>  
>               if (candidate == NULL || candidate->bif_dlt > bp->bif_dlt)
> @@ -1090,9 +1089,9 @@ out:
>   * Copy the interface name to the ifreq.
>   */
>  void
> -bpf_ifname(struct ifnet *ifp, struct ifreq *ifr)
> +bpf_ifname(struct bpf_if *bif, struct ifreq *ifr)
>  {
> -     bcopy(ifp->if_xname, ifr->ifr_name, IFNAMSIZ);
> +     bcopy(bif->bif_name, ifr->ifr_name, sizeof(ifr->ifr_name));
>  }
>  
>  /*
> @@ -1538,21 +1537,17 @@ bpf_put(struct bpf_d *bd)
>       free(bd, M_DEVBUF, sizeof(*bd));
>  }
>  
> -/*
> - * Attach an interface to bpf.  driverp is a pointer to a (struct bpf_if *)
> - * in the driver's softc; dlt is the link layer type; hdrlen is the fixed
> - * size of the link header (variable length headers not yet supported).
> - */
> -void
> -bpfattach(caddr_t *driverp, struct ifnet *ifp, u_int dlt, u_int hdrlen)
> +void *
> +bpfsattach(caddr_t *bpfp, const char *name, u_int dlt, u_int hdrlen)
>  {
>       struct bpf_if *bp;
>  
>       if ((bp = malloc(sizeof(*bp), M_DEVBUF, M_NOWAIT)) == NULL)
>               panic("bpfattach");
>       SRPL_INIT(&bp->bif_dlist);
> -     bp->bif_driverp = (struct bpf_if **)driverp;
> -     bp->bif_ifp = ifp;
> +     bp->bif_driverp = (struct bpf_if **)bpfp;
> +     bp->bif_name = name;
> +     bp->bif_ifp = NULL;
>       bp->bif_dlt = dlt;
>  
>       bp->bif_next = bpf_iflist;
> @@ -1567,6 +1562,17 @@ bpfattach(caddr_t *driverp, struct ifnet
>        * performance reasons and to alleviate alignment restrictions).
>        */
>       bp->bif_hdrlen = BPF_WORDALIGN(hdrlen + SIZEOF_BPF_HDR) - hdrlen;
> +
> +     return (bp);
> +}
> +
> +void
> +bpfattach(caddr_t *driverp, struct ifnet *ifp, u_int dlt, u_int hdrlen)
> +{
> +     struct bpf_if *bp;
> +
> +     bp = bpfsattach(driverp, ifp->if_xname, dlt, hdrlen);
> +     bp->bif_ifp = ifp;
>  }
>  
>  /* Detach an interface from its attached bpf device.  */
> @@ -1574,31 +1580,39 @@ void
>  bpfdetach(struct ifnet *ifp)
>  {
>       struct bpf_if *bp, *nbp, **pbp = &bpf_iflist;
> -     struct bpf_d *bd;
> -     int maj;
>  
>       KERNEL_ASSERT_LOCKED();
>  
>       for (bp = bpf_iflist; bp; bp = nbp) {
> -             nbp= bp->bif_next;
> +             nbp = bp->bif_next;
>               if (bp->bif_ifp == ifp) {
>                       *pbp = nbp;
>  
> -                     /* Locate the major number. */
> -                     for (maj = 0; maj < nchrdev; maj++)
> -                             if (cdevsw[maj].d_open == bpfopen)
> -                                     break;
> -
> -                     while ((bd = SRPL_FIRST_LOCKED(&bp->bif_dlist)))
> -                             vdevgone(maj, bd->bd_unit, bd->bd_unit, VCHR);
> -
> -                     free(bp, M_DEVBUF, sizeof *bp);
> +                     bpfsdetach(bp);
>               } else
>                       pbp = &bp->bif_next;
>       }
>       ifp->if_bpf = NULL;
>  }
>  
> +void
> +bpfsdetach(void *p)
> +{
> +     struct bpf_if *bp = p;
> +     struct bpf_d *bd;
> +     int maj;
> +
> +     /* Locate the major number. */
> +     for (maj = 0; maj < nchrdev; maj++)
> +             if (cdevsw[maj].d_open == bpfopen)
> +                     break;
> +
> +     while ((bd = SRPL_FIRST_LOCKED(&bp->bif_dlist)))
> +             vdevgone(maj, bd->bd_unit, bd->bd_unit, VCHR);
> +
> +     free(bp, M_DEVBUF, sizeof *bp);
> +}
> +
>  int
>  bpf_sysctl_locked(int *name, u_int namelen, void *oldp, size_t *oldlenp,
>      void *newp, size_t newlen)
> @@ -1674,14 +1688,14 @@ int
>  bpf_getdltlist(struct bpf_d *d, struct bpf_dltlist *bfl)
>  {
>       int n, error;
> -     struct ifnet *ifp;
>       struct bpf_if *bp;
> +     const char *name;
>  
> -     ifp = d->bd_bif->bif_ifp;
> +     name = d->bd_bif->bif_name;
>       n = 0;
>       error = 0;
>       for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
> -             if (bp->bif_ifp != ifp)
> +             if (strcmp(name, bp->bif_name) != 0)
>                       continue;
>               if (bfl->bfl_list != NULL) {
>                       if (n >= bfl->bfl_len)
> @@ -1704,15 +1718,17 @@ bpf_getdltlist(struct bpf_d *d, struct b
>  int
>  bpf_setdlt(struct bpf_d *d, u_int dlt)
>  {
> -     struct ifnet *ifp;
> +     const char *name;
>       struct bpf_if *bp;
>  
>       MUTEX_ASSERT_LOCKED(&d->bd_mtx);
>       if (d->bd_bif->bif_dlt == dlt)
>               return (0);
> -     ifp = d->bd_bif->bif_ifp;
> +     name = d->bd_bif->bif_name;
>       for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
> -             if (bp->bif_ifp == ifp && bp->bif_dlt == dlt)
> +             if (strcmp(name, bp->bif_name) != 0)
> +                     continue;
> +             if (bp->bif_dlt == dlt)
>                       break;
>       }
>       if (bp == NULL)
> Index: bpf.h
> ===================================================================
> RCS file: /cvs/src/sys/net/bpf.h,v
> retrieving revision 1.62
> diff -u -p -r1.62 bpf.h
> --- bpf.h     22 Feb 2017 09:56:03 -0000      1.62
> +++ bpf.h     10 Jan 2018 07:27:45 -0000
> @@ -313,6 +313,8 @@ int        bpf_mtap_af(caddr_t, u_int32_t, con
>  int   bpf_mtap_ether(caddr_t, const struct mbuf *, u_int);
>  void  bpfattach(caddr_t *, struct ifnet *, u_int, u_int);
>  void  bpfdetach(struct ifnet *);
> +void *bpfsattach(caddr_t *, const char *, u_int, u_int);
> +void  bpfsdetach(void *);
>  void  bpfilterattach(int);
>  
>  u_int         bpf_mfilter(const struct bpf_insn *, const struct mbuf *, 
> u_int);
> Index: bpfdesc.h
> ===================================================================
> RCS file: /cvs/src/sys/net/bpfdesc.h,v
> retrieving revision 1.35
> diff -u -p -r1.35 bpfdesc.h
> --- bpfdesc.h 24 Jan 2017 10:08:30 -0000      1.35
> +++ bpfdesc.h 10 Jan 2018 07:27:45 -0000
> @@ -103,6 +103,7 @@ struct bpf_if {
>       struct bpf_if **bif_driverp;    /* pointer into softc */
>       u_int bif_dlt;                  /* link layer type */
>       u_int bif_hdrlen;               /* length of header (with padding) */
> +     const char *bif_name;           /* name of "subsystem" */
>       struct ifnet *bif_ifp;          /* corresponding interface */
>  };
>  
> Index: pf.c
> ===================================================================
> RCS file: /cvs/src/sys/net/pf.c,v
> retrieving revision 1.1054
> diff -u -p -r1.1054 pf.c
> --- pf.c      29 Dec 2017 23:55:22 -0000      1.1054
> +++ pf.c      10 Jan 2018 07:27:45 -0000
> @@ -104,6 +104,11 @@
>  #include <ddb/db_interface.h>
>  #endif
>  
> +#if NBPFILTER > 0
> +#include <net/bpf.h>
> +caddr_t pf_bpf;
> +#endif
> +
>  /*
>   * Global variables
>   */
> @@ -6719,6 +6724,11 @@ pf_test(sa_family_t af, int fwdir, struc
>  
>       if (!pf_status.running)
>               return (PF_PASS);
> +
> +#if NBPFILTER > 0
> +     if (pf_bpf)
> +             bpf_mtap_af(pf_bpf, af, *m0, BPF_DIRECTION_IN);
> +#endif
>  
>  #if NCARP > 0
>       if (ifp->if_type == IFT_CARP && ifp->if_carpdev)
> Index: pf_ioctl.c
> ===================================================================
> RCS file: /cvs/src/sys/net/pf_ioctl.c,v
> retrieving revision 1.326
> diff -u -p -r1.326 pf_ioctl.c
> --- pf_ioctl.c        28 Nov 2017 16:05:46 -0000      1.326
> +++ pf_ioctl.c        10 Jan 2018 07:27:45 -0000
> @@ -35,6 +35,7 @@
>   *
>   */
>  
> +#include "bpfilter.h"
>  #include "pfsync.h"
>  #include "pflog.h"
>  
> @@ -84,6 +85,11 @@
>  #include <net/if_pfsync.h>
>  #endif /* NPFSYNC > 0 */
>  
> +#if NBPFILTER > 0
> +#include <net/bpf.h>
> +extern caddr_t pf_bpf;
> +#endif
> +
>  struct pool           pf_tag_pl;
>  
>  void                  pfattach(int);
> @@ -231,6 +237,10 @@ pfattach(int num)
>  
>       /* XXX do our best to avoid a conflict */
>       pf_status.hostid = arc4random();
> +
> +#if NBPFILTER > 0
> +     bpfsattach(&pf_bpf, "pf", DLT_LOOP, sizeof(u_int32_t));
> +#endif
>  }
>  
>  int
> 

Reply via email to