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
threshold. Inflight doesn't make sense on a LAN as it has
trouble figuring out the maximal bandwidth because of the coarse
tick granularity.
The sysctl net.inet.tcp.inflight.rttthresh specifies the threshold
in milliseconds below which inflight will disengage. It defaults
to 10ms.
Tested by: Joao Barros <joao.barros-at-gmail.com>,
Rich Murphey <rich-at-whiteoaklabs.com>
Sponsored by: TCP/IP Optimization Fundraise 2005
Having an additional MT_HEADER mbuf type is superfluous and redundant
as nothing depends on it. It only adds a layer of confusion. The
distinction between header mbuf's and data mbuf's is solely done
through the m->m_flags M_PKTHDR flag.
Non-native code is not changed in this commit. For compatibility
MT_HEADER is mapped to MT_DATA.
Sponsored by: TCP/IP Optimization Fundraise 2005
This is a special case because tcp_twstart() destroys a tcp control
block via tcp_discardcb() so we cannot call tcp_drop(struct *tcpcb) on
such connections. Use tcp_twclose() instead.
MFC after: 5 days
has been done in icmp_input() already.
This fixes the ICMP_UNREACH_NEEDFRAG case where no MTU was
proposed in the ICMP reply.
PR: kern/81813
Submitted by: Vitezslav Novy <vita at fio.cz>
MFC after: 3 days
- most of the kernel code will not care about the actual encoding of
scope zone IDs and won't touch "s6_addr16[1]" directly.
- similarly, most of the kernel code will not care about link-local
scoped addresses as a special case.
- scope boundary check will be stricter. For example, the current
*BSD code allows a packet with src=::1 and dst=(some global IPv6
address) to be sent outside of the node, if the application do:
s = socket(AF_INET6);
bind(s, "::1");
sendto(s, some_global_IPv6_addr);
This is clearly wrong, since ::1 is only meaningful within a single
node, but the current implementation of the *BSD kernel cannot
reject this attempt.
Submitted by: JINMEI Tatuya <jinmei__at__isl.rdc.toshiba.co.jp>
Obtained from: KAME
after PAWS checks. The symptom of this is an inconsistency in the cached
sack state, caused by the fact that the sack scoreboard was not being
updated for an ACK handled in the header prediction path.
Found by: Andrey Chernov.
Submitted by: Noritoshi Demizu, Raja Mukerji.
Approved by: re
Assert tcbinfo lock in tcp_close() due to its call to in{,6}_detach()
Assert tcbinfo lock in tcp_drop_syn_sent() due to its call to tcp_drop()
MFC after: 7 days
look up the packet size of the packet that generated the
response, step down the MTU by one step through ip_next_mtu()
and try again.
Suggested by: dwmalone
code readability and facilitates some anticipated optimizations in
tcp_sack_option().
- Remove tcp_print_holes() and TCP_SACK_DEBUG.
Submitted by: Raja Mukerji.
Reviewed by: Mohan Srinivasan, Noritoshi Demizu.
tcp_ctlinput() and subject it to active tcpcb and sequence
number checking. Previously any ICMP unreachable/needfrag
message would cause an update to the TCP hostcache. Now only
ICMP PMTU messages belonging to an active TCP session with
the correct src/dst/port and sequence number will update the
hostcache and complete the path MTU discovery process.
Note that we don't entirely implement the recommended counter
measures of Section 7.2 of the paper. However we close down
the possible degradation vector from trivially easy to really
complex and resource intensive. In addition we have limited
the smallest acceptable MTU with net.inet.tcp.minmss sysctl
for some time already, further reducing the effect of any
degradation due to an attack.
Security: draft-gont-tcpm-icmp-attacks-03.txt Section 7.2
MFC after: 3 days
ineffective, depreciated and can be abused to degrade the performance
of active TCP sessions if spoofed.
Replace a bogus call to tcp_quench() in tcp_output() with the direct
equivalent tcpcb variable assignment.
Security: draft-gont-tcpm-icmp-attacks-03.txt Section 7.1
MFC after: 3 days
a reassembly queue state structure, don't update (receiver) sack
report.
- Similarly, if tcp_drain() is called, freeing up all items on the
reassembly queue, clean the sack report.
Found, Submitted by: Noritoshi Demizu <demizu at dd dot iij4u dot or dot jp>
Reviewed by: Mohan Srinivasan (mohans at yahoo-inc dot com),
Raja Mukerji (raja at moselle dot com).
o Use SYSCTL_IN() macro instead of direct call of copyin(9).
Submitted by: ume
o Move sysctl_drop() implementation to sys/netinet/tcp_subr.c where
most of tcp sysctls live.
o There are net.inet[6].tcp[6].getcred sysctls already, no needs in
a separate struct tcp_ident_mapping.
Suggested by: ume
second; since the default hz has changed to 1000 times a second,
this resulted in unecessary work being performed.
MFC after: 2 weeks
Discussed with: phk, cperciva
General head nod: silby
tcpip_fillheaders()
tcp_discardcb()
tcp_close()
tcp_notify()
tcp_new_isn()
tcp_xmit_bandwidth_limit()
Fix a locking comment in tcp_twstart(): the pcbinfo will be locked (and
is asserted).
MFC after: 2 weeks
structure, so assert the inpcb lock associated with the tcptw.
Also assert the tcbinfo lock, as tcp_timewait() may call
tcp_twclose() or tcp_2msl_rest(), which require it. Since
tcp_timewait() is already called with that lock from tcp_input(),
this doesn't change current locking, merely documents reasons for
it.
In tcp_twstart(), assert the tcbinfo lock, as tcp_timer_2msl_rest()
is called, which requires that lock.
In tcp_twclose(), assert the tcbinfo lock, as tcp_timer_2msl_stop()
is called, which requires that lock.
Document the locking strategy for the time wait queues in tcp_timer.c,
which consists of protecting the time wait queues in the same manner
as the tcbinfo structure (using the tcbinfo lock).
In tcp_timer_2msl_reset(), assert the tcbinfo lock, as the time wait
queues are modified.
In tcp_timer_2msl_stop(), assert the tcbinfo lock, as the time wait
queues may be modified.
In tcp_timer_2msl_tw(), assert the tcbinfo lock, as the time wait
queues may be modified.
MFC after: 2 weeks
on the tcpcb, but also calls into tcp_close() and tcp_twrespond().
Annotate that tcp_twrecycleable() requires the inpcb lock because it does
a series of non-atomic reads of the tcpcb, but is currently called
without the inpcb lock by the caller. This is a bug.
Assert the inpcb lock in tcp_twclose() as it performs a read-modify-write
of the timewait structure/inpcb, and calls in_pcbdetach() which requires
the lock.
Assert the inpcb lock in tcp_twrespond(), as it performs multiple
non-atomic reads of the tcptw and inpcb structures, as well as calling
mac_create_mbuf_from_inpcb(), tcpip_fillheaders(), which require the
inpcb lock.
MFC after: 2 weeks
protects access to the ISN state variables.
Acquire the tcbinfo write lock in tcp_isn_tick() to synchronize
timer-driven isn bumping.
Staticize internal ISN variables since they're not used outside of
tcp_subr.c.
MFC after: 2 weeks
A complete rationale and discussion is given in this message
and the resulting discussion:
http://docs.freebsd.org/cgi/mid.cgi?4177C8AD.6060706
Note that this commit removes only the functional part of T/TCP
from the tcp_* related functions in the kernel. Other features
introduced with RFC1644 are left intact (socket layer changes,
sendmsg(2) on connection oriented protocols) and are meant to
be reused by a simpler and less intrusive reimplemention of the
previous T/TCP functionality.
Discussed on: -arch
(sorele()/sotryfree()):
- This permits the caller to acquire the accept mutex before the socket
mutex, avoiding sofree() having to drop the socket mutex and re-order,
which could lead to races permitting more than one thread to enter
sofree() after a socket is ready to be free'd.
- This also covers clearing of the so_pcb weak socket reference from
the protocol to the socket, preventing races in clearing and
evaluation of the reference such that sofree() might be called more
than once on the same socket.
This appears to close a race I was able to easily trigger by repeatedly
opening and resetting TCP connections to a host, in which the
tcp_close() code called as a result of the RST raced with the close()
of the accepted socket in the user process resulting in simultaneous
attempts to de-allocate the same socket. The new locking increases
the overhead for operations that may potentially free the socket, so we
will want to revise the synchronization strategy here as we normalize
the reference counting model for sockets. The use of the accept mutex
in freeing of sockets that are not listen sockets is primarily
motivated by the potential need to remove the socket from the
incomplete connection queue on its parent (listen) socket, so cleaning
up the reference model here may allow us to substantially weaken the
synchronization requirements.
RELENG_5_3 candidate.
MFC after: 3 days
Reviewed by: dwhite
Discussed with: gnn, dwhite, green
Reported by: Marc UBM Bocklet <ubm at u-boot-man dot de>
Reported by: Vlad <marchenko at gmail dot com>
to control the packets injected while in sack recovery (for both
retransmissions and new data).
- Cleanups to the sack codepaths in tcp_output.c and tcp_sack.c.
- Add a new sysctl (net.inet.tcp.sack.initburst) that controls the
number of sack retransmissions done upon initiation of sack recovery.
Submitted by: Mohan Srinivasan <mohans@yahoo-inc.com>
- Trailing tab/space cleanup
- Remove spurious spaces between or before tabs
This change avoids touching files that Andre likely has in his working
set for PFIL hooks changes for IPFW/DUMMYNET.
Approved by: re (scottl)
Submitted by: Xin LI <delphij@frontfree.net>
for structures with timers in them. It might be that a timer might fire
even when the associated structure has already been free'd. Having type-
stable storage in this case is beneficial for graceful failure handling and
debugging.
Discussed with: bosko, tegge, rwatson
structures, allowing in6_pcbnotify() to lock the pcbinfo and each
inpcb that it notifies of ICMPv6 events. This prevents inpcb
assertions from firing when IPv6 generates and delievers event
notifications for inpcbs.
Reported by: kuriyama
Tested by: kuriyama
somewhat clearer, but more importantly allows for a consistent naming
scheme for suser_cred flags.
The old name is still defined, but will be removed in a few days (unless I
hear any complaints...)
Discussed with: rwatson, scottl
Requested by: jhb
