The filter is called from the network hot path and must not sleep.
The filter runs with the descriptor lock held and does not manipulates the
buffers, so it is not necessary sleep when the hold buffer is in use.
Just ignore the hold buffer contents when it is being copied to user space
(when hold buffer in use is set).
This fix the "Sleeping thread owns a non-sleepable lock" panic when the
userland thread is too busy reading the packets from bpf(4).
PR: 200323
MFC after: 2 weeks
Sponsored by: Rubicon Communications (Netgate)
The first one never triggers because bpf_canfreebuf() can only be true for
zero-copy buffers and zero-copy buffers are not read with read(2).
The second also never triggers, because we check the free buffer before
calling ROTATE_BUFFERS(). If the hold buffer is in use the free buffer
will be NULL and there is nothing else to do besides drop the packet. If
the free buffer isn't NULL the hold buffer _is_ free and it is safe to
rotate the buffers.
Update the comment in ROTATE_BUFFERS macro to match the logic described
here.
While here fix a few typos in comments.
MFC after: 2 weeks
Sponsored by: Rubicon Communications (Netgate)
the buffer is allocated we are committed to a particular buffer method
(BPF_BUFMODE_BUFFER in this case).
If we are using zero-copy buffers, the userland program must register its
buffers before set the interface.
If we are using kernel memory buffers, we can allocate the buffer at the
time that the interface is being set.
This fix allows the usage of BIOCSETBUFMODE after r235746.
Update the comments to reflect the recent changes.
MFC after: 2 weeks
Sponsored by: Rubicon Communications (Netgate)
A couple of fields are still exposed via struct bpf_if_ext so that
bpf_peers_present() can be inlined into its callers. However, this change
eliminates some type duplication in the resulting CTF container, since
otherwise ctfmerge(1) propagates the duplication through all types that
contain a struct bpf_if.
Differential Revision: https://reviews.freebsd.org/D2319
Reviewed by: melifaro, rpaulo
dhclient opens bpf as write-only to send packets. It never reads received
packets from that descriptor, but processing them in kernel takes time.
Especially much time takes packet timestamping on systems with expensive
timecounter, such as bhyve guest, where network speed dropped in half.
MFC after: 2 weeks
Sponsored by: iXsystems, Inc.
Quoting 19 years bpf.4 manual from bpf-1.2a1:
"
(SIOCGIFADDR is obsolete under BSD systems. SIOCGIFCONF should be
used to query link-level addresses.)
"
* SIOCGIFADDR was not imported in NetBSD (bpf.c 1.36) and OpenBSD.
* Last bits (e.g. manpage claiming SIOCGIFADDR exists) was cleaned
from NetBSD via kern/21513 5 years ago,
from OpenBSD via documentation/6352 5 years ago.
directly accessed. Although this will work on some platforms, it can
throw an exception if the pointer is invalid and then panic the kernel.
Add a missing SYSCTL_IN() of "SCTP_BASE_STATS" structure.
MFC after: 3 days
Sponsored by: Mellanox Technologies
Direct bpf(4) consumers should now work fine with this tunable turned on.
In fact, the only case when optimized_writers can change program
behavior is direct bpf(4) consumer setting its read filter to
catch-all one.
MFC after: 2 weeks
Sponsored by: Yandex LLC
rather than just void *.
Then, as part of this, convert a couple of mbuf m->m_data accesses
to mtod(m, const void *).
Reviewed by: markm
Approved by: security-officer (delphij)
Sponsored by: Netflix, Inc.
to this event, adding if_var.h to files that do need it. Also, include
all includes that now are included due to implicit pollution via if_var.h
Sponsored by: Netflix
Sponsored by: Nginx, Inc.
and that can drive someone crazy. While m_get2() is young and not
documented yet, change its order of arguments to match m_getm2().
Sorry for churn, but better now than later.
cause kernel panics.
Add a flag to the bpf descriptor to indicate whether the hold buffer
is in use. In bpfread(), set the "hold buffer in use" flag before
dropping the descriptor lock during the call to bpf_uiomove().
Everywhere else the hold buffer is used or changed, wait while
the hold buffer is in use by bpfread(). Add a KASSERT in bpfread()
after re-acquiring the descriptor lock to assist uncovering any
additional hold buffer races.
Eliminate bpf_buffer_alloc() and allocate BPF buffers on descriptor creation and BIOCSBLEN ioctl.
This permits us not to allocate buffers inside bpf_attachd() which is protected by global lock.
Approved by: kib(mentor)
MFC in: 4 weeks
'flags' field is added to the end of bpf_if structure. Currently the only
flag is BPFIF_FLAG_DYING which is set on bpf detach and checked by bpf_attachd()
Problem can be easily triggered on SMP stable/[89] by the following command (sort of):
'while true; do ifconfig vlan222 create vlan 222 vlandev em0 up ; tcpdump -pi vlan222 & ; ifconfig vlan222 destroy ; done'
Fix possible use-after-free when BPF detaches itself from interface, freeing bpf_bif memory,
while interface is still UP and there can be routes via this interface.
Freeing is now delayed till ifnet_departure_event is received via eventhandler(9) api.
Convert bpfd rwlock back to mutex due lack of performance gain (currently checking if packet
matches filter is done without holding bpfd lock and we have to acquire write lock if packet matches)
Approved by: kib(mentor)
MFC in: 4 weeks
Fix panic on tcpdump being attached to interface being removed (introduced by r233937, pointed by hrs@ and adrian@)
Protect most of bpf_setf() by BPF global lock
Add several forgotten assertions (thanks to adrian@)
Document current locking model inside bpf.c
Document EVENTHANDLER(9) usage inside BPF.
Approved by: kib(mentor)
Tested by: gnn
MFC in: 4 weeks
Linux and Solaris (at least OpenSolaris) has PF_PACKET socket families to send
raw ethernet frames. The only FreeBSD interface that can be used to send raw frames
is BPF. As a result, many programs like cdpd, lldpd, various dhcp stuff uses
BPF only to send data. This leads us to the situation when software like cdpd,
being run on high-traffic-volume interface significantly reduces overall performance
since we have to acquire additional locks for every packet.
Here we add sysctl that changes BPF behavior in the following way:
If program came and opens BPF socket without explicitly specifyin read filter we
assume it to be write-only and add it to special writer-only per-interface list.
This makes bpf_peers_present() return 0, so no additional overhead is introduced.
After filter is supplied, descriptor is added to original per-interface list permitting
packets to be captured.
Unfortunately, pcap_open_live() sets catch-all filter itself for the purpose of
setting snap length.
Fortunately, most programs explicitly sets (event catch-all) filter after that.
tcpdump(1) is a good example.
So a bit hackis approach is taken: we upgrade description only after second
BIOCSETF is received.
Sysctl is named net.bpf.optimize_writers and is turned off by default.
- While here, document all sysctl variables in bpf.4
Sponsored by Yandex LLC
Reviewed by: glebius (previous version)
Reviewed by: silence on -net@
Approved by: (mentor)
MFC after: 4 weeks
Interface locks and descriptor locks are converted from mutex(9) to rwlock(9).
This greately improves performance: in most common case we need to acquire 1
reader lock instead of 2 mutexes.
- Remove filter(descriptor) (reader) lock in bpf_mtap[2]
This was suggested by glebius@. We protect filter by requesting interface
writer lock on filter change.
- Cover struct bpf_if under BPF_INTERNAL define. This permits including bpf.h
without including rwlock stuff. However, this is is temporary solution,
struct bpf_if should be made opaque for any external caller.
Found by: Dmitrij Tejblum <tejblum@yandex-team.ru>
Sponsored by: Yandex LLC
Reviewed by: glebius (previous version)
Reviewed by: silence on -net@
Approved by: (mentor)
MFC after: 3 weeks
using the o32 ABI. This mostly follows nwhitehorn's lead in implementing
COMPAT_FREEBSD32 on powerpc64.
o) Add a new type to the freebsd32 compat layer, time32_t, which is time_t in the
32-bit ABI being used. Since the MIPS port is relatively-new, even the 32-bit
ABIs use a 64-bit time_t.
o) Because time{spec,val}32 has the same size and layout as time{spec,val} on MIPS
with 32-bit compatibility, then, disable some code which assumes otherwise
wrongly when built for MIPS. A more general macro to check in this case would
seem like a good idea eventually. If someone adds support for using n32
userland with n64 kernels on MIPS, then they will have to add a variety of
flags related to each piece of the ABI that can vary. That's probably the
right time to generalize further.
o) Add MIPS to the list of architectures which use PAD64_REQUIRED in the
freebsd32 compat code. Probably this should be generalized at some point.
Reviewed by: gonzo
bpf_iflist list which reference the specified ifnet. The existing implementation
only removes the first matching bpf_if found in the list, effectively leaking
list entries if an ifnet has been bpfattach()ed multiple times with different
DLTs.
Fix the leak by performing the detach logic in a loop, stopping when all bpf_if
structs referencing the specified ifnet have been detached and removed from the
bpf_iflist list.
Whilst here, also:
- Remove the unnecessary "bp->bif_ifp == NULL" check, as a bpf_if should never
exist in the list with a NULL ifnet pointer.
- Except when INVARIANTS is in the kernel config, silently ignore the case where
no bpf_if referencing the specified ifnet is found, as it is harmless and does
not require user attention.
Reviewed by: csjp
MFC after: 1 week
aspect of time stamp configuration per interface rather than per BPF
descriptor. Prior to this, the order in which BPF devices were opened and the
per descriptor time stamp configuration settings could cause non-deterministic
and unintended behaviour with respect to time stamping. With the new scheme, a
BPF attached interface's tscfg sysctl entry can be set to "default", "none",
"fast", "normal" or "external". Setting "default" means use the system default
option (set with the net.bpf.tscfg.default sysctl), "none" means do not
generate time stamps for tapped packets, "fast" means generate time stamps for
tapped packets using a hz granularity system clock read, "normal" means
generate time stamps for tapped packets using a full timecounter granularity
system clock read and "external" (currently unimplemented) means use the time
stamp provided with the packet from an underlying source.
- Utilise the recently introduced sysclock_getsnapshot() and
sysclock_snap2bintime() KPIs to ensure the system clock is only read once per
packet, regardless of the number of BPF descriptors and time stamp formats
requested. Use the per BPF attached interface time stamp configuration to
control if sysclock_getsnapshot() is called and whether the system clock read
is fast or normal. The per BPF descriptor time stamp configuration is then
used to control how the system clock snapshot is converted to a bintime by
sysclock_snap2bintime().
- Remove all FAST related BPF descriptor flag variants. Performing a "fast"
read of the system clock is now controlled per BPF attached interface using
the net.bpf.tscfg sysctl tree.
- Update the bpf.4 man page.
Committed on behalf of Julien Ridoux and Darryl Veitch from the University of
Melbourne, Australia, as part of the FreeBSD Foundation funded "Feed-Forward
Clock Synchronization Algorithms" project.
For more information, see http://www.synclab.org/radclock/
In collaboration with: Julien Ridoux (jridoux at unimelb edu au)
contain both a regular timestamp obtained from the system clock and the
current feed-forward ffcounter value. This enables new possibilities including
comparison of timekeeping performance and timestamp correction during post
processing.
- Add the net.bpf.ffclock_tstamp sysctl to provide a choice between timestamping
packets using the feedback or feed-forward system clock.
Committed on behalf of Julien Ridoux and Darryl Veitch from the University of
Melbourne, Australia, as part of the FreeBSD Foundation funded "Feed-Forward
Clock Synchronization Algorithms" project.
For more information, see http://www.synclab.org/radclock/
Submitted by: Julien Ridoux (jridoux at unimelb edu au)
The SYSCTL_NODE macro defines a list that stores all child-elements of
that node. If there's no SYSCTL_DECL macro anywhere else, there's no
reason why it shouldn't be static.
If a selinfo object is recorded (via selrecord()) and then it is
quickly destroyed, with the waiters missing the opportunity to awake,
at the next iteration they will find the selinfo object destroyed,
causing a PF#.
That happens because the selinfo interface has no way to drain the
waiters before to destroy the registered selinfo object. Also this
race is quite rare to get in practice, because it would require a
selrecord(), a poll request by another thread and a quick destruction
of the selrecord()'ed selinfo object.
Fix this by adding the seldrain() routine which should be called
before to destroy the selinfo objects (in order to avoid such case),
and fix the present cases where it might have already been called.
Sometimes, the context is safe enough to prevent this type of race,
like it happens in device drivers which installs selinfo objects on
poll callbacks. There, the destruction of the selinfo object happens
at driver detach time, when all the filedescriptors should be already
closed, thus there cannot be a race.
For this case, mfi(4) device driver can be set as an example, as it
implements a full correct logic for preventing this from happening.
Sponsored by: Sandvine Incorporated
Reported by: rstone
Tested by: pluknet
Reviewed by: jhb, kib
Approved by: re (bz)
MFC after: 3 weeks
- Allow setting format, resolution and accuracy of BPF time stamps per
listener. Previously, we were only able to use microtime(9). Now we can
set various resolutions and accuracies with ioctl(2) BIOCSTSTAMP command.
Similarly, we can get the current resolution and accuracy with BIOCGTSTAMP
command. Document all supported options in bpf(4) and their uses.
- Introduce new time stamp 'struct bpf_ts' and header 'struct bpf_xhdr'.
The new time stamp has both 64-bit second and fractional parts. bpf_xhdr
has this time stamp instead of 'struct timeval' for bh_tstamp. The new
structures let us use bh_tstamp of same size on both 32-bit and 64-bit
platforms without adding additional shims for 32-bit binaries. On 64-bit
platforms, size of BPF header does not change compared to bpf_hdr as its
members are already all 64-bit long. On 32-bit platforms, the size may
increase by 8 bytes. For backward compatibility, struct bpf_hdr with
struct timeval is still the default header unless new time stamp format is
explicitly requested. However, the behaviour may change in the future and
all relevant code is wrapped around "#ifdef BURN_BRIDGES" for now.
- Add experimental support for tagging mbufs with time stamps from a lower
layer, e.g., device driver. Currently, mbuf_tags(9) is used to tag mbufs.
The time stamps must be uptime in 'struct bintime' format as binuptime(9)
and getbinuptime(9) do.
Reviewed by: net@
Add missing CURVNET_RESTORE() calls for multiple code paths, to stop
leaking the currently cached vnet into callers and to the process.
Sponsored by: The FreeBSD Foundation
Sponsored by: CK Software GmbH
MFC after: 4 days
bd_compat32 field of struct bpf_d is kept unconditionally to not
impose the requirement of including "opt_compat.h" on all numerous
users of bpfdesc.h.
Submitted by: jhb (version for 6.x)
Reviewed and tested by: emaste
MFC after: 2 weeks
- Add a missing callout_drain(9) before the descriptor deallocation.[1]
- Prefer callout_init_mtx(9) over callout_init(9) and let the callout
subsystem handle the mutex for callout function.
PR: kern/144453
Submitted by: Alexander Sack (asack at niksun dot com)[1]
MFC after: 1 week
