dropped. This prevents a bug introduced during the socket/pcb refcounting
work from occuring, in which occasionally the retransmit timer may fire
after a connection has been reset, resulting in the resulting R|A TCP
packet having a source port of 0, as the port reservation has been
released.
While here, fixing up some RUNLOCK->WUNLOCK bugs.
MFC after: 1 month
(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
Since tags are kept while packet resides in kernelspace, it's possible to
use other kernel facilities (like netgraph nodes) for altering those tags.
Submitted by: Andrey Elsukov <bu7cher at yandex dot ru>
Submitted by: Vadim Goncharov <vadimnuclight at tpu dot ru>
Approved by: glebius (mentor)
Idea from: OpenBSD PF
MFC after: 1 month
a defensive programming measure.
Note that whilst these members are not used by the ip_output()
path, we are passing an instance of struct ip_moptions here
which is declared on the stack (which could be considered a
bad thing).
ip_output() does not consume struct ip_moptions, but in case it
does in future, declare an in_multi vector on the stack too to
behave more like ip_findmoptions() does.
as not connected. In soclose() case rip_detach() will kill inpcb for
us later.
It makes rawconnect regression test do not panic a system.
Reviewed by: rwatson
X-MFC after: with all 1th April inpcb changes
connections and get rid of the flow_id as it is not guaranteed to be stable
some (most?) current implementations seem to just zero it out.
PR: kern/88664
Reported by: jylefort
Submitted by: Joost Bekkers (w/ changes)
Tested by "regisr" <regisrApoboxDcom>
By making the imo_membership array a dynamically allocated vector,
this minimizes disruption to existing IPv4 multicast code. This
change breaks the ABI for the kernel module ip_mroute.ko, and may
cause a small amount of churn for folks working on the IGMPv3 merge.
Previously, sockets were subject to a compile-time limitation on
the number of IPv4 group memberships, which was hard-coded to 20.
The imo_membership relationship, however, is 1:1 with regards to
a tuple of multicast group address and interface address. Users who
ran routing protocols such as OSPF ran into this limitation on machines
with a large system interface tree.
seperately. Also use pfil hook/unhook instead of keeping the check
functions in pfil just to return there based on the sysctl. While here fix
some whitespace on a nearby SYSCTL_ macro.
for signicantly optimized UDP socket I/O when using a single UDP
socket from many threads or processes that share it, by avoiding
significant locking and other overhead in the general sosend()
path that isn't necessary for simple datagram sockets. Specifically,
this change results in a significant performance improvement for
threaded name service in BIND9 under load.
Suggested by: Jinmei_Tatsuya at isc dot org
after ipsec4_output processing else KAME IPSec using the handbook
configuration with gif(4) will panic the kernel.
Problem reported by: t. patterson <tp lot.org>
Tested by: t. patterson <tp lot.org>
return NULL. In principle this shouldn't change the behavior, but
avoids returning a potentially invalid/inappropriate pointer to
the caller.
Found with: Coverity Prevent (tm)
Submitted by: pjd
MFC after: 3 months
the fact that the loop through inpcb's in udp_input() tracks the
last inpcb while looping. We keep that name in the calling loop
but not in the delivery routine itself.
MFC after: 3 months
into in_pcbdrop(). Expand logic to detach the inpcb from its bound
address/port so that dropping a TCP connection releases the inpcb resource
reservation, which since the introduction of socket/pcb reference count
updates, has been persisting until the socket closed rather than being
released implicitly due to prior freeing of the inpcb on TCP drop.
MFC after: 3 months
common pcb tear-down logic into tcp_detach(), which is called from
either. Invoke tcp_drop() from the tcp_usr_abort() path rather than
tcp_disconnect(), as we want to drop it immediately not perform a
FIN sequence. This is one reason why some people were experiencing
panics in sodealloc(), as the netisr and aborting thread were
simultaneously trying to tear down the socket. This bug could often
be reproduced using repeated runs of the listenclose regression test.
MFC after: 3 months
PR: 96090
Reported by: Peter Kostouros <kpeter at melbpc dot org dot au>, kris
Tested by: Peter Kostouros <kpeter at melbpc dot org dot au>, kris
number state, rather than re-using pcbinfo. This introduces some
additional mutex operations during isn query, but avoids hitting the TCP
pcbinfo lock out of yet another frequently firing TCP timer.
MFC after: 3 months
holding the inpcb lock is sufficient to prevent races in reading
the address and port, as both the inpcb lock and pcbinfo lock are
required to change the address/port.
Improve consistency of spelling in assertions about inp != NULL.
MFC after: 3 months
reference. For now, we allow the possibility that the in_ppcb
pointer in the inpcb may be NULL if a timewait socket has had its
tcptw structure recycled. This allows tcp_timewait() to
consistently unlock the inpcb.
Reported by: Kazuaki Oda <kaakun at highway dot ne dot jp>
MFC after: 3 months
(tcp_sack_output_debug checks cached hints aginst computed values by walking the
scoreboard and reports discrepancies). The sack hinting code has been stable for
many months now so it is time for the debug code to go. Leaving tcp_sack_output_debug
ifdef'ed out in case we need to resurrect it at a later point.
tcp_timewait(). This corrects a bug (or lack of fixing of a bug)
in tcp_input.c:1.295.
Submitted by: Kazuaki Oda <kaakun at highway dot ne dot jp>
MFC after: 3 months
NULL. We currently do allow this to happen, but may want to remove that
possibility in the future. This case can occur when a socket is left
open after TCP wraps up, and the timewait state is recycled. This will
be cleaned up in the future.
Found by: Kazuaki Oda <kaakun at highway dot ne dot jp>
MFC after: 3 months
The INP_DROPPED check replaces the current NULL checks; the INP_TIMEWAIT
checks appear to have always been required, but not been there, which
is/was a bug. This avoids unconditionally casting of in_ppcb to a tcpcb,
when it may be a twtcb, which may have resulted in obscure ICMP-related
panics in earlier releases.
MFC after: 3 months
casts.
Consistently use intotw() to cast inp_ppcb pointers to struct tcptw *
pointers.
Consistently use intotcpcb() to cast inp_ppcb pointers to struct tcpcb *
pointers.
Don't assign tp to the results to intotcpcb() during variable declation
at the top of functions, as that is before the asserts relating to
locking have been performed. Do this later in the function after
appropriate assertions have run to allow that operation to be conisdered
safe.
MFC after: 3 months
immediately rather than jumping to the normal output handling, which
assumes we've pulled out the inpcb, which hasn't happened at this
point (and isn't necessary).
Return ECONNABORTED instead of EINVAL when the inpcb has entered
INP_TIMEWAIT or INP_DROPPED, as this is the documented error value.
This may correct the panic seen by Ganbold.
MFC after: 1 month
Reported by: Ganbold <ganbold at micom dot mng dot net>
disconnect for fully connected sockets was dropped, meaning that if
the socket was closed while the connection was alive, it would be
leaked. Structure tcp_usr_detach() so that there are two clear
parts: initiating disconnect, and reclaiming state, and reintroduce
the tcp_disconnect() call in the first part.
MFC after: 3 months
socket can have a tcp connection that has entered time wait
attached to it, in the event that shutdown() is called on the
socket and the FINs properly exchange before close(). In this
case we don't detach or free the inpcb, just leave the tcptw
detached and freed, but we must release the inpcb lock (which we
didn't previously).
MFC after: 3 months
pru_abort(), pru_detach(), and in_pcbdetach():
- Universally support and enforce the invariant that so_pcb is
never NULL, converting dozens of unnecessary NULL checks into
assertions, and eliminating dozens of unnecessary error handling
cases in protocol code.
- In some cases, eliminate unnecessary pcbinfo locking, as it is no
longer required to ensure so_pcb != NULL. For example, the receive
code no longer requires the pcbinfo lock, and the send code only
requires it if building a new connection on an otherwise unconnected
socket triggered via sendto() with an address. This should
significnatly reduce tcbinfo lock contention in the receive and send
cases.
- In order to support the invariant that so_pcb != NULL, it is now
necessary for the TCP code to not discard the tcpcb any time a
connection is dropped, but instead leave the tcpcb until the socket
is shutdown. This case is handled by setting INP_DROPPED, to
substitute for using a NULL so_pcb to indicate that the connection
has been dropped. This requires the inpcb lock, but not the pcbinfo
lock.
- Unlike all other protocols in the tree, TCP may need to retain access
to the socket after the file descriptor has been closed. Set
SS_PROTOREF in tcp_detach() in order to prevent the socket from being
freed, and add a flag, INP_SOCKREF, so that the TCP code knows whether
or not it needs to free the socket when the connection finally does
close. The typical case where this occurs is if close() is called on
a TCP socket before all sent data in the send socket buffer has been
transmitted or acknowledged. If INP_SOCKREF is found when the
connection is dropped, we release the inpcb, tcpcb, and socket instead
of flagging INP_DROPPED.
- Abort and detach protocol switch methods no longer return failures,
nor attempt to free sockets, as the socket layer does this.
- Annotate the existence of a long-standing race in the TCP timer code,
in which timers are stopped but not drained when the socket is freed,
as waiting for drain may lead to deadlocks, or have to occur in a
context where waiting is not permitted. This race has been handled
by testing to see if the tcpcb pointer in the inpcb is NULL (and vice
versa), which is not normally permitted, but may be true of a inpcb
and tcpcb have been freed. Add a counter to test how often this race
has actually occurred, and a large comment for each instance where
we compare potentially freed memory with NULL. This will have to be
fixed in the near future, but requires is to further address how to
handle the timer shutdown shutdown issue.
- Several TCP calls no longer potentially free the passed inpcb/tcpcb,
so no longer need to return a pointer to indicate whether the argument
passed in is still valid.
- Un-macroize debugging and locking setup for various protocol switch
methods for TCP, as it lead to more obscurity, and as locking becomes
more customized to the methods, offers less benefit.
- Assert copyright on tcp_usrreq.c due to significant modifications that
have been made as part of this work.
These changes significantly modify the memory management and connection
logic of our TCP implementation, and are (as such) High Risk Changes,
and likely to contain serious bugs. Please report problems to the
current@ mailing list ASAP, ideally with simple test cases, and
optionally, packet traces.
MFC after: 3 months
pru_abort(), pru_detach(), and in_pcbdetach():
- Universally support and enforce the invariant that so_pcb is
never NULL, converting dozens of unnecessary NULL checks into
assertions, and eliminating dozens of unnecessary error handling
cases in protocol code.
- In some cases, eliminate unnecessary pcbinfo locking, as it is no
longer required to ensure so_pcb != NULL. For example, in protocol
shutdown methods, and in raw IP send.
- Abort and detach protocol switch methods no longer return failures,
nor attempt to free sockets, as the socket layer does this.
- Invoke in_pcbfree() after in_pcbdetach() in order to free the
detached in_pcb structure for a socket.
MFC after: 3 months
