1) Move core entropy-pool code and source/sink/sample management code
to sys/kern from sys/dev.
2) Remove use of NRND as test for presence of entropy-pool code throughout
source tree.
3) Remove use of RND_ENABLED in device drivers as microoptimization to
avoid expensive operations on disabled entropy sources; make the
rnd_add calls do this directly so all callers benefit.
4) Fix bug in recent rnd_add_data()/rnd_add_uint32() changes that might
have lead to slight entropy overestimation for some sources.
5) Add new source types for environmental sensors, power sensors, VM
system events, and skew between clocks, with a sample implementation
for each.
ok releng to go in before the branch due to the difficulty of later
pullup (widespread #ifdef removal and moved files). Tested with release
builds on amd64 and evbarm and live testing on amd64.
methods called Vestigial Time-Wait (VTW) and Maximum Segment Lifetime
Truncation (MSLT).
MSLT and VTW were contributed by Coyote Point Systems, Inc.
Even after a TCP session enters the TIME_WAIT state, its corresponding
socket and protocol control blocks (PCBs) stick around until the TCP
Maximum Segment Lifetime (MSL) expires. On a host whose workload
necessarily creates and closes down many TCP sockets, the sockets & PCBs
for TCP sessions in TIME_WAIT state amount to many megabytes of dead
weight in RAM.
Maximum Segment Lifetimes Truncation (MSLT) assigns each TCP session to
a class based on the nearness of the peer. Corresponding to each class
is an MSL, and a session uses the MSL of its class. The classes are
loopback (local host equals remote host), local (local host and remote
host are on the same link/subnet), and remote (local host and remote
host communicate via one or more gateways). Classes corresponding to
nearer peers have lower MSLs by default: 2 seconds for loopback, 10
seconds for local, 60 seconds for remote. Loopback and local sessions
expire more quickly when MSLT is used.
Vestigial Time-Wait (VTW) replaces a TIME_WAIT session's PCB/socket
dead weight with a compact representation of the session, called a
"vestigial PCB". VTW data structures are designed to be very fast and
memory-efficient: for fast insertion and lookup of vestigial PCBs,
the PCBs are stored in a hash table that is designed to minimize the
number of cacheline visits per lookup/insertion. The memory both
for vestigial PCBs and for elements of the PCB hashtable come from
fixed-size pools, and linked data structures exploit this to conserve
memory by representing references with a narrow index/offset from the
start of a pool instead of a pointer. When space for new vestigial PCBs
runs out, VTW makes room by discarding old vestigial PCBs, oldest first.
VTW cooperates with MSLT.
It may help to think of VTW as a "FIN cache" by analogy to the SYN
cache.
A 2.8-GHz Pentium 4 running a test workload that creates TIME_WAIT
sessions as fast as it can is approximately 17% idle when VTW is active
versus 0% idle when VTW is inactive. It has 103 megabytes more free RAM
when VTW is active (approximately 64k vestigial PCBs are created) than
when it is inactive.
Long ago, the storage representations of srtt and rttvar were changed
from the 4.4BSD scheme, and the comments are out of sync with the
code. This commit rewrites most of the comments that explain the RTO
calculations, and points out some issues in the code.
Joint work with Bev Schwartz of BBN (original analysis and comments),
but I have rewritten and extended them, so errors are mine.
This material is based upon work supported by the Defense Advanced
Research Projects Agency and Space and Naval Warfare Systems Center,
Pacific, under Contract No. N66001-09-C-2073. Approved for Public
Release, Distribution Unlimited
- Socket layer becomes MP safe.
- Unix protocols become MP safe.
- Allows protocol processing interrupts to safely block on locks.
- Fixes a number of race conditions.
With much feedback from matt@ and plunky@.
route_in6, struct route_iso), replacing all caches with a struct
route.
The principle benefit of this change is that all of the protocol
families can benefit from route cache-invalidation, which is
necessary for correct routing. Route-cache invalidation fixes an
ancient PR, kern/3508, at long last; it fixes various other PRs,
also.
Discussions with and ideas from Joerg Sonnenberger influenced this
work tremendously. Of course, all design oversights and bugs are
mine.
DETAILS
1 I added to each address family a pool of sockaddrs. I have
introduced routines for allocating, copying, and duplicating,
and freeing sockaddrs:
struct sockaddr *sockaddr_alloc(sa_family_t af, int flags);
struct sockaddr *sockaddr_copy(struct sockaddr *dst,
const struct sockaddr *src);
struct sockaddr *sockaddr_dup(const struct sockaddr *src, int flags);
void sockaddr_free(struct sockaddr *sa);
sockaddr_alloc() returns either a sockaddr from the pool belonging
to the specified family, or NULL if the pool is exhausted. The
returned sockaddr has the right size for that family; sa_family
and sa_len fields are initialized to the family and sockaddr
length---e.g., sa_family = AF_INET and sa_len = sizeof(struct
sockaddr_in). sockaddr_free() puts the given sockaddr back into
its family's pool.
sockaddr_dup() and sockaddr_copy() work analogously to strdup()
and strcpy(), respectively. sockaddr_copy() KASSERTs that the
family of the destination and source sockaddrs are alike.
The 'flags' argumet for sockaddr_alloc() and sockaddr_dup() is
passed directly to pool_get(9).
2 I added routines for initializing sockaddrs in each address
family, sockaddr_in_init(), sockaddr_in6_init(), sockaddr_iso_init(),
etc. They are fairly self-explanatory.
3 structs route_in6 and route_iso are no more. All protocol families
use struct route. I have changed the route cache, 'struct route',
so that it does not contain storage space for a sockaddr. Instead,
struct route points to a sockaddr coming from the pool the sockaddr
belongs to. I added a new method to struct route, rtcache_setdst(),
for setting the cache destination:
int rtcache_setdst(struct route *, const struct sockaddr *);
rtcache_setdst() returns 0 on success, or ENOMEM if no memory is
available to create the sockaddr storage.
It is now possible for rtcache_getdst() to return NULL if, say,
rtcache_setdst() failed. I check the return value for NULL
everywhere in the kernel.
4 Each routing domain (struct domain) has a list of live route
caches, dom_rtcache. rtflushall(sa_family_t af) looks up the
domain indicated by 'af', walks the domain's list of route caches
and invalidates each one.
parentheses in return statements.
Cosmetic: don't open-code TAILQ_FOREACH().
Cosmetic: change types of variables to avoid oodles of casts: in
in6_src.c, avoid casts by changing several route_in6 pointers
to struct route pointers. Remove unnecessary casts to caddr_t
elsewhere.
Pave the way for eliminating address family-specific route caches:
soon, struct route will not embed a sockaddr, but it will hold
a reference to an external sockaddr, instead. We will set the
destination sockaddr using rtcache_setdst(). (I created a stub
for it, but it isn't used anywhere, yet.) rtcache_free() will
free the sockaddr. I have extracted from rtcache_free() a helper
subroutine, rtcache_clear(). rtcache_clear() will "forget" a
cached route, but it will not forget the destination by releasing
the sockaddr. I use rtcache_clear() instead of rtcache_free()
in rtcache_update(), because rtcache_update() is not supposed
to forget the destination.
Constify:
1 Introduce const accessor for route->ro_dst, rtcache_getdst().
2 Constify the 'dst' argument to ifnet->if_output(). This
led me to constify a lot of code called by output routines.
3 Constify the sockaddr argument to protosw->pr_ctlinput. This
led me to constify a lot of code called by ctlinput routines.
4 Introduce const macros for converting from a generic sockaddr
to family-specific sockaddrs, e.g., sockaddr_in: satocsin6,
satocsin, et cetera.
from Kentaro A. Kurahone, with minor adjustments by me.
the ack prediction part of the original patch was omitted because
it's a separate change. reviewed by Rui Paulo.
The code to generate an ISS via an MD5 hash has been present in the
NetBSD kernel since 2001, but it wasn't even exported to userland at
that time. It was agreed on tech-net with the original author <thorpej>
that we should let the user decide if he wants to enable it or not.
Not enabled by default.
happen in the TCP stack, this interface calls the specified callback to
handle the situation according to the currently selected congestion
control algorithm.
A new sysctl node was created: net.inet.tcp.congctl.{available,selected}
with obvious meanings.
The old net.inet.tcp.newreno MIB was removed.
The API is discussed in tcp_congctl(9).
In the near future, it will be possible to selected a congestion control
algorithm on a per-socket basis.
Discussed on tech-net and reviewed by <yamt>.
Both available for IPv4 and IPv6.
Basic implementation test results are available at
http://netbsd-soc.sourceforge.net/projects/ecn/testresults.html.
Work sponsored by the Google Summer of Code project 2006.
Special thanks to Kentaro Kurahone, Allen Briggs and Matt Thomas for their
help, comments and support during the project.
http://www.gont.com.ar/drafts/icmp-attacks-against-tcp.html
1. Don't act on ICMP-need-frag immediately if adhoc checks on the
advertised MTU fail. The MTU update is delayed until a TCP retransmit
happens.
2. Ignore ICMP Source Quench messages meant for TCP connections.
From OpenBSD.
- introduce t_segqlen, the number of segments in segq/timeq.
the name is from freebsd.
- rather than maintaining a copy of sack blocks (rcv_sack_block[]),
build it directly from the segment list when needed.
