MFC r323864

bridge: Set module version

This ensures that the loader will not load the module if it's also built in to
the kernel.

PR: 220860
Submitted by: Eugene Grosbein <eugen@freebsd.org>

MFC 312782

bridge: Release the bridge lock when calling bridge_set_ifcap()

This calls ioctl() handlers for the different interfaces in the bridge.
These handlers expect to get called in an ioctl context where it's safe
for them to sleep. We may not sleep with the bridge lock held.

However, we still need to protect the interface list, to ensure it
doesn't get changed while we iterate over it.
Use BRIDGE_XLOCK(), which prevents bridge members from being removed.
Adding bridge members is safe, because it uses LIST_INSERT_HEAD().

This caused panics when adding xen interfaces to a bridge.

PR: 216304
Reviewed by: ae
Sponsored by: RootBSD
Differential Revision: https://reviews.freebsd.org/D9290

MFC r306289:

bridge: Fix fragment handling and memory leak

Fragmented UDP and ICMP packets were corrupted if a firewall with reassembling
feature (like pf'scrub) is enabled on the bridge. This patch fixes corrupted
packet problem and the panic (triggered easly with low RAM) as explain in PR
185633.

bridge_pfil and bridge_fragment relationship:

bridge_pfil() receive (IN direction) packets and sent it to the firewall The
firewall can be configured for reassembling fragmented packet (like pf'scrubing)
in one mbuf chain when bridge_pfil() need to send this reassembled packet to the
outgoing interface, it needs to re-fragment it by using bridge_fragment()
bridge_fragment() had to split this mbuf (using ip_fragment) first then
had to M_PREPEND each packet in the mbuf chain for adding Ethernet
header.

But M_PREPEND can sometime create a new mbuf on the begining of the mbuf chain,
then the "main" pointer of this mbuf chain should be updated and this case is
tottaly forgotten. The original bridge_fragment code (Revision 158140,
2006 April 29) came from OpenBSD, and the call to bridge_enqueue was
embedded. But on FreeBSD, bridge_enqueue() is done after bridge_fragment(),
then the original OpenBSD code can't work as-it of FreeBSD.

PR: 185633
Submitted by: Olivier Cochard-Labbé

MFC r303009: Negotiate/disable TXCSUM_IPV6 same as TXCSUM.

MFC r284348: Fix panic when adding vtnet interfaces to a bridge

vtnet interfaces are always in promiscuous mode (at least if the
VIRTIO_NET_F_CTRL_RX feature is not negotiated with the host). if_promisc() on
a vtnet interface returned ENOTSUP although it has IFF_PROMISC set. This
confused the bridge code. Instead we now accept all enable/disable promiscuous
commands (and always keep IFF_PROMISC set).

There are also two issues with the if_bridge error handling.

If if_promisc() fails it uses bridge_delete_member() to clean up. This tries to
disable promiscuous mode on the interface. That runs into an assert, because
promiscuous mode was never set in the first place. (That's the panic reported in
PR 200210.)
We can only unset promiscuous mode if the interface actually is promiscuous.
This goes against the reference counting done by if_promisc(), but only the
first/last if_promic() calls can actually fail, so this is safe.

A second issue is a double free of bif. It's already freed by
bridge_delete_member().

PR: 200210

MFC r284348: Fix panic when adding vtnet interfaces to a bridge

vtnet interfaces are always in promiscuous mode (at least if the
VIRTIO_NET_F_CTRL_RX feature is not negotiated with the host). if_promisc() on
a vtnet interface returned ENOTSUP although it has IFF_PROMISC set. This
confused the bridge code. Instead we now accept all enable/disable promiscuous
commands (and always keep IFF_PROMISC set).

There are also two issues with the if_bridge error handling.

If if_promisc() fails it uses bridge_delete_member() to clean up. This tries to
disable promiscuous mode on the interface. That runs into an assert, because
promiscuous mode was never set in the first place. (That's the panic reported in
PR 200210.)
We can only unset promiscuous mode if the interface actually is promiscuous.
This goes against the reference counting done by if_promisc(), but only the
first/last if_promic() calls can actually fail, so this is safe.

A second issue is a double free of bif. It's already freed by
bridge_delete_member().

PR: 200210