(1) bpf peer attaches to interface netif0
(2) Packet is received by netif0
(3) ifp->if_bpf pointer is checked and handed off to bpf
(4) bpf peer detaches from netif0 resulting in ifp->if_bpf being
initialized to NULL.
(5) ifp->if_bpf is dereferenced by bpf machinery
(6) Kaboom
This race condition likely explains the various different kernel panics
reported around sending SIGINT to tcpdump or dhclient processes. But really
this race can result in kernel panics anywhere you have frequent bpf attach
and detach operations with high packet per second load.
Summary of changes:
- Remove the bpf interface's "driverp" member
- When we attach bpf interfaces, we now set the ifp->if_bpf member to the
bpf interface structure. Once this is done, ifp->if_bpf should never be
NULL. [1]
- Introduce bpf_peers_present function, an inline operation which will do
a lockless read bpf peer list associated with the interface. It should
be noted that the bpf code will pickup the bpf_interface lock before adding
or removing bpf peers. This should serialize the access to the bpf descriptor
list, removing the race.
- Expose the bpf_if structure in bpf.h so that the bpf_peers_present function
can use it. This also removes the struct bpf_if; hack that was there.
- Adjust all consumers of the raw if_bpf structure to use bpf_peers_present
Now what happens is:
(1) Packet is received by netif0
(2) Check to see if bpf descriptor list is empty
(3) Pickup the bpf interface lock
(4) Hand packet off to process
From the attach/detach side:
(1) Pickup the bpf interface lock
(2) Add/remove from bpf descriptor list
Now that we are storing the bpf interface structure with the ifnet, there is
is no need to walk the bpf interface list to locate the correct bpf interface.
We now simply look up the interface, and initialize the pointer. This has a
nice side effect of changing a bpf interface attach operation from O(N) (where
N is the number of bpf interfaces), to O(1).
[1] From now on, we can no longer check ifp->if_bpf to tell us whether or
not we have any bpf peers that might be interested in receiving packets.
In collaboration with: sam@
MFC after: 1 month
o don't send management frames if the IFF_DRV_RUNNING flag is not set.
this prevents the timeout watchdog from being potentially re-armed
when the interface is brought down.
fixes a crash that occurs with RT2661 based adapters.
reported by Arnaud Lacombe.
generations of 802.11abg chipsets from Ralink Technology.
Get rid of the pccard front-end while I'm here since all adapters are
cardbus ones.
Obtained from: OpenBSD
could get an interrupt after we free the ifp, and the interrupt
handler depended on the ifp being still alive, this could, in theory,
cause a crash. Eliminate this possibility by moving the if_free to
after the bus_teardown_intr() call.
depends, like all other pccard drivers, indirectly through kobj on
pccard. Therefore, it is not appropriate to force pccard to be loaded
when if_ral.ko is loaded. This makes it possible to load if_ral w/o
loading pccard.ko on, eg, pci only systems.
o add ic_curchan and use it uniformly for specifying the current
channel instead of overloading ic->ic_bss->ni_chan (or in some
drivers ic_ibss_chan)
o add ieee80211_scanparams structure to encapsulate scanning-related
state captured for rx frames
o move rx beacon+probe response frame handling into separate routines
o change beacon+probe response handling to treat the scan table
more like a scan cache--look for an existing entry before adding
a new one; this combined with ic_curchan use corrects handling of
stations that were previously found at a different channel
o move adhoc neighbor discovery by beacon+probe response frames to
a new ieee80211_add_neighbor routine
Reviewed by: avatar
Tested by: avatar, Michal Mertl
MFC after: 2 weeks
IFF_DRV_RUNNING, as well as the move from ifnet.if_flags to
ifnet.if_drv_flags. Device drivers are now responsible for
synchronizing access to these flags, as they are in if_drv_flags. This
helps prevent races between the network stack and device driver in
maintaining the interface flags field.
Many __FreeBSD__ and __FreeBSD_version checks maintained and continued;
some less so.
Reviewed by: pjd, bz
MFC after: 7 days
was written in the old fragmented mbuf chain instead of the defragmented
one. Thus, the duration field of outgoing frames was incorrect.
o Only call m_defrag() if the mbuf fragmentation threshold is greater
than what is currently supported by the driver.
Reviewed by: silby (mentor)
Approved by: re (scottl)
Provide a backwards compatible way to have the extra macro by defining
PCCARD_API_LEVEL 5 before including pccarddevs for driver writers that
want/need to have the same driver on 5 and 6 with pccard attachments.
Approved by: re (dwhite)
struct ifnet or the layer 2 common structure it was embedded in have
been replaced with a struct ifnet pointer to be filled by a call to the
new function, if_alloc(). The layer 2 common structure is also allocated
via if_alloc() based on the interface type. It is hung off the new
struct ifnet member, if_l2com.
This change removes the size of these structures from the kernel ABI and
will allow us to better manage them as interfaces come and go.
Other changes of note:
- Struct arpcom is no longer referenced in normal interface code.
Instead the Ethernet address is accessed via the IFP2ENADDR() macro.
To enforce this ac_enaddr has been renamed to _ac_enaddr.
- The second argument to ether_ifattach is now always the mac address
from driver private storage rather than sometimes being ac_enaddr.
Reviewed by: sobomax, sam
