(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
Changelog towards if_iwi.c 1.26 (some changes have been committed separately
in the mean time):
- add led support
- add firmware loading on demand
- auto-restart firmware when it crashes
- serialize operations sent to the firmware to reduce firmware crashes
- add power save operation support
- remove incorrect specification of tx power control capability
- add radio on/off switch support
- improve net80211 state machine operation
- recognize and handle beacon miss
- handle authentication and association failures better
- add shared key authentication
- fix ibss mode (many changes)
- fix wme (many changes)
- correct radiotap support (many changes)
- correct bus dma setup of s/g
- correct various locking issues
- fix monitor mode
- fix scanning (many changes)
- recover from wedged scan requests
- respect active channel list
- eliminate cases where interface was marked down on error
- don't treat parity errors as fatal
- reclaim mgt frames immediately from tx queue
- correct interrupt handling, ack early (from NetBSD)
- fix short/long preamble handling
Committed with RELENG_6 compat #if's, should compile in RELENG_6. Requires
net/iwi-firmware-kmod to function.
Much work done by: sam
Tested by: many (freebsd-net), ume, luigi
MFC after: 4 weeks
o call firmware_put() early to release the firmware module
o on firmware panics or watchdog timeouts, schedule a task to reinitialize
the interface (we may sleep in iwi_init())
o discard oversized rx frames
o stop processing interrupts after a firmware fatal error or a radio kill
o clarify the possible values for the 'antenna' sysctl.
o by default, let the firmware do antenna diversity.
the firmware will periodically switch to another antenna to evaluate the
signal quality.
o Change MEM_READ_1/MEM_READ_4 into macros (move them to if_iwireg.h)
o Add support for association LED
o Silently discard f/w notifications that are unknown (fixes spurious
"unknown notification 15" in logs with latest firmware)
o Fix scanning of 5GHz channels
directory by default) without requiring the user to load them by hand using
e.g iwicontrol. Get rid of the old ioctl crud.
Updated iwi-firmware port coming soon.
Obtained from: OpenBSD
a new mbuf, just discard the received frame and reuse the old mbuf.
This should fix kernel panics on high network traffic.
Obtained from: NetBSD (joerg@)
MFC after: 2 weeks
the 5GHz band.
o Enable 802.11a channels scanning for 2915ABG adapters.
o Fix a typo (negociated->negotiated).
With hints from NetBSD.
MFC after: 2 days
in an IBSS. Store ids directly into ieee80211_node's instead of managing
our own private association table. Idea and code by Sam Leffler.
Submitted by: sam
MFC after: 5 days
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.
o Allow association with APs that do not broadcast SSID (with hints from
Nick Hudson and Hajimu Umemoto).
o IFQ_DRV_PREPEND mbuf when h/w ring is full so it can be sent later.
o Increment if_oerrors when appropriate.
o Did some cleanup while I'm here.
MFC after: 1 day
o management of multiple tx rings (up to 4)
o setting of WME IE in association requests
Some features are still missing though, like the possibility to override
the default cwmin/cwmax/asfn values of each tx queues.
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
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
and on resume (reported to fix issues with ACPI)
o Add monitor mode support
o Add WPA (802.11i) support (not tested extensively though!)
o Add a device specific sysctl to control the tx antenna (default to
antenna diversity)
o Fix sensitivity setting
o Fix setting of the capinfo field when associating
o Temporarly disable 802.11a channels scanning that was causing firmware
panics with 2915ABG adapters until I find a better fix. This breaks
802.11a support.
o Temporarly switch back to software WEP until I implement hardware
encryption for AES and TKIP too.
Approved by: silby (mentor)
