Re: git: c81dd8e5fe72 - main - bpf: Add IfAPI analogue for bpf_peers_present()

> On Oct 14, 2023, at 1:22 AM, Justin Hibbits <jhibbits@freebsd.org> wrote:
> 
> The branch main has been updated by jhibbits:
> 
> URL: https://cgit.FreeBSD.org/src/commit/?id=c81dd8e5fe72d0c7ec055c8621bb2da3a3627abf
> 
> commit c81dd8e5fe72d0c7ec055c8621bb2da3a3627abf
> Author:     Justin Hibbits <jhibbits@FreeBSD.org>
> AuthorDate: 2023-10-04 20:56:52 +0000
> Commit:     Justin Hibbits <jhibbits@FreeBSD.org>
> CommitDate: 2023-10-13 17:12:44 +0000
> 
>    bpf: Add IfAPI analogue for bpf_peers_present()
> 
>    An interface's bpf could feasibly not exist, in which case
>    bpf_peers_present() would panic from a NULL pointer dereference.  Solve
>    this by adding a new IfAPI that includes a NULL check.  Since this API

The initial version DOES have NULL check. But that is redundant and removed
from the committed version.

>    is used in only a handful of locations, it reduces the the NULL check
>    scope over inserting the check into bpf_peers_present().
> 
>    Sponsored by:   Juniper Networks, Inc.
>    MFC after:      1 week
> ---
> sys/dev/firewire/if_fwip.c    |  4 ++--
> sys/dev/hyperv/netvsc/if_hn.c |  4 ++--
> sys/dev/my/if_my.c            |  2 +-
> sys/dev/usb/usb_pf.c          |  4 +---
> sys/net/bpf.c                 | 14 ++++++++++++++
> sys/net/bpf.h                 |  1 +
> 6 files changed, 21 insertions(+), 8 deletions(-)
> 
> diff --git a/sys/dev/firewire/if_fwip.c b/sys/dev/firewire/if_fwip.c
> index 5237c555d999..b698db6c9620 100644
> --- a/sys/dev/firewire/if_fwip.c
> +++ b/sys/dev/firewire/if_fwip.c
> @@ -780,7 +780,7 @@ fwip_stream_input(struct fw_xferq *xferq)
> 		 * Record the sender ID for possible BPF usage.
> 		 */
> 		src = ntohl(p[1]) >> 16;
> -		if (bpf_peers_present(if_getbpf(ifp))) {
> +		if (bpf_peers_present_if(ifp)) {
> 			mtag = m_tag_alloc(MTAG_FIREWIRE,
> 			    MTAG_FIREWIRE_SENDER_EUID,
> 			    2*sizeof(uint32_t), M_NOWAIT);
> @@ -880,7 +880,7 @@ fwip_unicast_input(struct fw_xfer *xfer)
> 		goto done;
> 	}
> 
> -	if (bpf_peers_present(if_getbpf(ifp))) {
> +	if (bpf_peers_present_if(ifp)) {
> 		/*
> 		 * Record the sender ID for possible BPF usage.
> 		 */
> diff --git a/sys/dev/hyperv/netvsc/if_hn.c b/sys/dev/hyperv/netvsc/if_hn.c
> index 7d8e1914163e..f6f885873a79 100644
> --- a/sys/dev/hyperv/netvsc/if_hn.c
> +++ b/sys/dev/hyperv/netvsc/if_hn.c
> @@ -3262,7 +3262,7 @@ hn_txpkt(if_t ifp, struct hn_tx_ring *txr, struct hn_txdesc *txd)
> 	int error, send_failed = 0, has_bpf;
> 
> again:
> -	has_bpf = bpf_peers_present(if_getbpf(ifp));
> +	has_bpf = bpf_peers_present_if(ifp);
> 	if (has_bpf) {
> 		/*
> 		 * Make sure that this txd and any aggregated txds are not
> @@ -5972,7 +5972,7 @@ hn_transmit(if_t ifp, struct mbuf *m)
> 			omcast = (m->m_flags & M_MCAST) != 0;
> 
> 			if (sc->hn_xvf_flags & HN_XVFFLAG_ACCBPF) {
> -				if (bpf_peers_present(if_getbpf(ifp))) {
> +				if (bpf_peers_present_if(ifp)) {
> 					m_bpf = m_copypacket(m, M_NOWAIT);
> 					if (m_bpf == NULL) {
> 						/*
> diff --git a/sys/dev/my/if_my.c b/sys/dev/my/if_my.c
> index 2bf4573d337b..631c38df9dca 100644
> --- a/sys/dev/my/if_my.c
> +++ b/sys/dev/my/if_my.c
> @@ -1152,7 +1152,7 @@ my_rxeof(struct my_softc * sc)
> 		 * broadcast packet, multicast packet, matches our ethernet
> 		 * address or the interface is in promiscuous mode.
> 		 */
> -		if (bpf_peers_present(if_getbpf(ifp))) {
> +		if (bpf_peers_present_if(ifp)) {
> 			bpf_mtap_if(ifp, m);
> 			if (if_getflags(ifp) & IFF_PROMISC &&
> 			    (bcmp(eh->ether_dhost, if_getlladdr(sc->my_ifp),
> diff --git a/sys/dev/usb/usb_pf.c b/sys/dev/usb/usb_pf.c
> index 43e819684857..4da59419a7c6 100644
> --- a/sys/dev/usb/usb_pf.c
> +++ b/sys/dev/usb/usb_pf.c
> @@ -408,9 +408,7 @@ usbpf_xfertap(struct usb_xfer *xfer, int type)
> 	bus = xfer->xroot->bus;
> 
> 	/* sanity checks */
> -	if (bus->ifp == NULL || if_getbpf(bus->ifp) == NULL)
> -		return;
> -	if (!bpf_peers_present(if_getbpf(bus->ifp)))
> +	if (bus->ifp == NULL || !bpf_peers_present_if(bus->ifp))
> 		return;
> 
> 	totlen = usbpf_xfer_precompute_size(xfer, type);
> diff --git a/sys/net/bpf.c b/sys/net/bpf.c
> index 8ca6e941e646..96420b709911 100644
> --- a/sys/net/bpf.c
> +++ b/sys/net/bpf.c
> @@ -2879,6 +2879,14 @@ bpfdetach(struct ifnet *ifp)
> 	BPF_UNLOCK();
> }
> 
> +bool
> +bpf_peers_present_if(struct ifnet *ifp)
> +{
> +	struct bpf_if *bp = ifp->if_bpf;
> +
> +	return (bpf_peers_present(bp) > 0);
> +}
> +
> /*
>  * Get a list of available data link type of the interface.
>  */
> @@ -3162,6 +3170,12 @@ bpfdetach(struct ifnet *ifp)
> {
> }
> 
> +bool
> +bpf_peers_present_if(struct ifnet *ifp)
> +{
> +	return (false);
> +}
> +
> u_int
> bpf_filter(const struct bpf_insn *pc, u_char *p, u_int wirelen, u_int buflen)
> {
> diff --git a/sys/net/bpf.h b/sys/net/bpf.h
> index 924dea5fc9f4..31968445aac1 100644
> --- a/sys/net/bpf.h
> +++ b/sys/net/bpf.h
> @@ -428,6 +428,7 @@ void	 bpf_mtap2_if(struct ifnet *, void *, u_int, struct mbuf *);
> void	 bpfattach(struct ifnet *, u_int, u_int);
> void	 bpfattach2(struct ifnet *, u_int, u_int, struct bpf_if **);
> void	 bpfdetach(struct ifnet *);
> +bool	 bpf_peers_present_if(struct ifnet *);
> #ifdef VIMAGE
> int	 bpf_get_bp_params(struct bpf_if *, u_int *, u_int *);
> #endif