consumers which fork after the shared pages have been setup. pflogd(8)
is an example. The problem is understood and there is a fix coming in
shortly.
Folks who want to continue using it can do so by setting
net.bpf.zerocopy_enable
to 1.
Discussed with: rwatson
are not currently owned by userspace before clearing or rotating them.
Otherwise we may not play by the rules of the shared memory protocol,
potentially corrupting packet data or causing userspace applications
that are playing by the rules to spin due to being notified that a
buffer is complete but the shared memory header not reflecting that.
This behavior was seen with pflogd by a number of reporters; note that
this fix is not sufficient to get pflogd properly working with
zero-copy BPF, due to pflogd opening the BPF device before forking,
leading to the shared memory buffer not being propery inherited in the
privilege-separated child. We're still deciding how to fix that
problem.
This change exposes buffer-model specific strategy information in
reset_d(), which will be fixed at a later date once we've decided how
best to improve the BPF buffer abstraction.
Reviewed by: csjp
Reported by: keramida
whitespace) macros from p4/vimage branch.
Do a better job at enclosing all instantiations of globals
scheduled for virtualization in #ifdef VIMAGE_GLOBALS blocks.
De-virtualize and mark as const saorder_state_alive and
saorder_state_any arrays from ipsec code, given that they are never
updated at runtime, so virtualizing them would be pointless.
Reviewed by: bz, julian
Approved by: julian (mentor)
Obtained from: //depot/projects/vimage-commit2/...
X-MFC after: never
Sponsored by: NLnet Foundation, The FreeBSD Foundation
Right now the bpf(4) driver uses the cloning API to generate /dev/bpf%u.
When an application such as tcpdump needs a BPF, it opens /dev/bpf0,
/dev/bpf1, etc. until it opens the first available device node. We used
this approach, because our devfs implementation didn't allow
per-descriptor data.
Now that we can, make it use devfs_get_cdevpriv() to obtain the private
data. To remain compatible with the existing implementation, add a
symlink from /dev/bpf0 to /dev/bpf. I've already changed libpcap to
compile with HAVE_CLONING_BPF, which makes it use /dev/bpf. There may be
other applications in the base system (dhclient) that use the loop to
obtain a valid bpf.
Discussed on: src-committers
Approved by: csjp
There is no way for the caller to tell us which direction this packet is
going. With the bpf_mtap{2} routines, we can check the interface pointer.
MFC after: 2 weeks
just like BIOCSETF but it doesn't drop all the packets buffered on
the discriptor and reset the statistics.
Also, when setting the write filter, don't drop packets waiting to
be read or reset the statistics.
PR: 118486
Submitted by: Matthew Luckie <mluckie@cs.waikato.ac.nz>
MFC after: 1 month
is reclaimed by the kernel. This fixes a bug resulted in the kernel
over writing packet data while user-space was still processing it when
zerocopy is enabled. (Or a panic if invariants was enabled).
Discussed with: rwatson
buffer kernel descriptors, which is used to allow the buffer
currently in the BPF "store" position to be assigned to userspace
when it fills, even if userspace hasn't acknowledged the buffer
in the "hold" position yet. To implement this, notify the buffer
model when a buffer becomes full, and check that the store buffer
is writable, not just for it being full, before trying to append
new packet data. Shared memory buffers will be assigned to
userspace at most once per fill, be it in the store or in the
hold position.
This removes the restriction that at most one shared memory can
by owned by userspace, reducing the chances that userspace will
need to call select() after acknowledging one buffer in order to
wait for the next buffer when under high load. This more fully
realizes the goal of zero system calls in order to process a
high-speed packet stream from BPF.
Update bpf.4 to reflect that both buffers may be owned by userspace
at once; caution against assuming this.
Removed dead code that assumed that M_TRYWAIT can return NULL; it's not true
since the advent of MBUMA.
Reviewed by: arch
There are ongoing disputes as to whether we want to switch to directly using
UMA flags M_WAITOK/M_NOWAIT for mbuf(9) allocation.
bpf_canfreebuf() in order to avoid potentially calling a non-inlinable
but trivial function in zero-copy buffer mode for every packet
received when we couldn't free the buffer anyway.
MFC after: 4 months
overhead of packet capture by allowing a user process to directly "loan"
buffer memory to the kernel rather than using read(2) to explicitly copy
data from kernel address space.
The user process will issue new BPF ioctls to set the shared memory
buffer mode and provide pointers to buffers and their size. The kernel
then wires and maps the pages into kernel address space using sf_buf(9),
which on supporting architectures will use the direct map region. The
current "buffered" access mode remains the default, and support for
zero-copy buffers must, for the time being, be explicitly enabled using
a sysctl for the kernel to accept requests to use it.
The kernel and user process synchronize use of the buffers with atomic
operations, avoiding the need for system calls under load; the user
process may use select()/poll()/kqueue() to manage blocking while
waiting for network data if the user process is able to consume data
faster than the kernel generates it. Patchs to libpcap are available
to allow libpcap applications to transparently take advantage of this
support. Detailed information on the new API may be found in bpf(4),
including specific atomic operations and memory barriers required to
synchronize buffer use safely.
These changes modify the base BPF implementation to (roughly) abstrac
the current buffer model, allowing the new shared memory model to be
added, and add new monitoring statistics for netstat to print. The
implementation, with the exception of some monitoring hanges that break
the netstat monitoring ABI for BPF, will be MFC'd.
Zerocopy bpf buffers are still considered experimental are disabled
by default. To experiment with this new facility, adjust the
net.bpf.zerocopy_enable sysctl variable to 1.
Changes to libpcap will be made available as a patch for the time being,
and further refinements to the implementation are expected.
Sponsored by: Seccuris Inc.
In collaboration with: rwatson
Tested by: pwood, gallatin
MFC after: 4 months [1]
[1] Certain portions will probably not be MFCed, specifically things
that can break the monitoring ABI.
after each SYSINIT() macro invocation. This makes a number of
lightweight C parsers much happier with the FreeBSD kernel
source, including cflow's prcc and lxr.
MFC after: 1 month
Discussed with: imp, rink
from Mac OS X Leopard--rationalize naming for entry points to
the following general forms:
mac_<object>_<method/action>
mac_<object>_check_<method/action>
The previous naming scheme was inconsistent and mostly
reversed from the new scheme. Also, make object types more
consistent and remove spaces from object types that contain
multiple parts ("posix_sem" -> "posixsem") to make mechanical
parsing easier. Introduce a new "netinet" object type for
certain IPv4/IPv6-related methods. Also simplify, slightly,
some entry point names.
All MAC policy modules will need to be recompiled, and modules
not updates as part of this commit will need to be modified to
conform to the new KPI.
Sponsored by: SPARTA (original patches against Mac OS X)
Obtained from: TrustedBSD Project, Apple Computer
This fixes the process portion of the bpf(4) stats if the peer forks
into the background after it's opened the descriptor. This bug
results in the following behavior for netstat -B:
# netstat -B
Pid Netif Flags Recv Drop Match Sblen Hblen Command
netstat: kern.proc.pid failed: No such process
78023 em0 p--s-- 2237404 43119 2237404 13986 0 ??????
MFC after: 1 week
flags, the absense of these flags causes problems in other areas such as
bridging which expect them to be correct.
At the moment only Ethernet DLTs are checked.
Reviewed by: bms, csjp, sam
Approved by: re (bmah)
previously conditionally acquired Giant based on debug.mpsafenet. As that
has now been removed, they are no longer required. Removing them
significantly simplifies error-handling in the socket layer, eliminated
quite a bit of unwinding of locking in error cases.
While here clean up the now unneeded opt_net.h, which previously was used
for the NET_WITH_GIANT kernel option. Clean up some related gotos for
consistency.
Reviewed by: bz, csjp
Tested by: kris
Approved by: re (kensmith)
will intialize the the header length and re-initialize the mbuf pointer
to reference the mbuf that is allocated after moving user supplied packet
data in.
ioctl routines if we are running with !mpsafenet
- Change un-conditional Giant acquisition around ifpromisc
to occur only if we are running with !mpsafenet
With these locking bits in place, we can now remove the Giant
requirement from BPF, so drop the D_NEEDGIANT device flag.
This change removes Giant acquisitions around BPF device
handlers (read, write, ioctl etc).
MFC after: 1 month
Discussed with: rwatson
- BIOCGDIRECTION and BIOCSDIRECTION get or set the setting determining
whether incoming, outgoing, or all packets on the interface should be
returned by BPF. Set to BPF_D_IN to see only incoming packets on the
interface. Set to BPF_D_INOUT to see packets originating locally and
remotely on the interface. Set to BPF_D_OUT to see only outgoing
packets on the interface. This setting is initialized to BPF_D_INOUT
by default. BIOCGSEESENT and BIOCSSEESENT are obsoleted by these but
kept for backward compatibility.
- BIOCFEEDBACK sets packet feedback mode. This allows injected packets
to be fed back as input to the interface when output via the interface is
successful. When BPF_D_INOUT direction is set, injected outgoing packet
is not returned by BPF to avoid duplication. This flag is initialized to
zero by default.
Note that libpcap has been modified to support BPF_D_OUT direction for
pcap_setdirection(3) and PCAP_D_OUT direction is functional now.
Reviewed by: rwatson
specific privilege names to a broad range of privileges. These may
require some future tweaking.
Sponsored by: nCircle Network Security, Inc.
Obtained from: TrustedBSD Project
Discussed on: arch@
Reviewed (at least in part) by: mlaier, jmg, pjd, bde, ceri,
Alex Lyashkov <umka at sevcity dot net>,
Skip Ford <skip dot ford at verizon dot net>,
Antoine Brodin <antoine dot brodin at laposte dot net>
begun with a repo-copy of mac.h to mac_framework.h. sys/mac.h now
contains the userspace and user<->kernel API and definitions, with all
in-kernel interfaces moved to mac_framework.h, which is now included
across most of the kernel instead.
This change is the first step in a larger cleanup and sweep of MAC
Framework interfaces in the kernel, and will not be MFC'd.
Obtained from: TrustedBSD Project
Sponsored by: SPARTA
take a timeval indicating when the packet was captured. Move
microtime() to the calling functions and grab the timestamp as soon
as we know that we're going to call catchpacket at least once.
This means that we call microtime() once per matched packet, as
opposed to once per matched packet per bpf listener. It also means
that we return the same timestamp to all bpf listeners, rather than
slightly different ones.
It would be more accurate to call microtime() even earlier for all
packets, as you have to grab (1+#listener) locks before you can
determine if the packet will be logged. You could always grab a
timestamp before the locks, but microtime() can be costly, so this
didn't seem like a good idea.
(I guess most ethernet interfaces will have a bpf listener these
days because of dhclient. That means that we could be doing two bpf
locks on most packets going through the interface.)
PR: 71711
already locked. The reason to do this is to avoid two lock+unlock operations
in a row. We need the lock here to serialize access to bd_pid for stats
collection purposes.
Drop the locks all together on detach, as they will be picked up by
knlist_remove.
This should fix a failed locking assertion when kqueue is being used with bpf
descriptors.
Discussed with: jmg
pointer to a zeroed, statically allocated bpf_if structure. This way the
LIST_EMPTY() macro will always return true. This allows us to remove the
additional unconditional memory reference for each packet in the fast path.
Discussed with: sam
(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
Use the following kernel configuration option to enable:
options BPF_JITTER
If you want to use bpf_filter() instead (e. g., debugging), do:
sysctl net.bpf.jitter.enable=0
to turn it off.
Currently BIOCSETWF and bpf_mtap2() are unsupported, and bpf_mtap() is
partially supported because 1) no need, 2) avoid expensive m_copydata(9).
Obtained from: WinPcap 3.1 (for i386)
refresh the PID which has the descriptor open. The PID is refreshed in various
operations like ioctl(2), kevent(2) or poll(2). This produces more accurate
information about current bpf consumers. While we are here remove the bd_pcomm
member of the bpf stats structure because now that we have an accurate PID we
can lookup the via the kern.proc.pid sysctl variable. This is the trick that
NetBSD decided to use to deal with this issue.
Special care needs to be taken when MFC'ing this change, as we have made a
change to the bpf stats structure. What will end up happening is we will leave
the pcomm structure but just mark it as being un-used. This way we keep the ABI
in tact.
MFC after: 1 month
Discussed with: Rui Paulo < rpaulo at NetBSD dot org >
enhance the security of bpf(4) by further relinquishing the privilege of
the bpf(4) consumer (assuming the ioctl commands are being implemented).
Once BIOCLOCK is executed, the device becomes locked which prevents the
execution of ioctl(2) commands which can change the underly parameters of the
bpf(4) device. An example might be the setting of bpf(4) filter programs or
attaching to different network interfaces.
BIOCSETWF can be used to set write filters for outgoing packets. Currently if
a bpf(4) consumer is compromised, the bpf(4) descriptor can essentially be used
as a raw socket, regardless of consumer's UID. Write filters give users the
ability to constrain which packets can be sent through the bpf(4) descriptor.
These features are currently implemented by a couple programs which came from
OpenBSD, such as the new dhclient and pflogd.
-Modify bpf_setf(9) to accept a "cmd" parameter. This will be used to specify
whether a read or write filter is to be set.
-Add a bpf(4) filter program as a parameter to bpf_movein(9) as we will run the
filter program on the mbuf data once we move the packet in from user-space.
-Rather than execute two uiomove operations, (one for the link header and the
other for the packet data), execute one and manually copy the linker header
into the sockaddr structure via bcopy.
-Restructure bpf_setf to compensate for write filters, as well as read.
-Adjust bpf(4) stats structures to include a bd_locked member.
It should be noted that the FreeBSD and OpenBSD implementations differ a bit in
the sense that we unconditionally enforce the lock, where OpenBSD enforces it
only if the calling credential is not root.
Idea from: OpenBSD
Reviewed by: mlaier
