fields between host and network byte order. The details:
o icmp_error() now does not add IP header length. This fixes the problem
when icmp_error() is called from ip_forward(). In this case the ip_len
of the original IP datagram returned with ICMP error was wrong.
o icmp_error() expects all three fields, ip_len, ip_id and ip_off in host
byte order, so DTRT and convert these fields back to network byte order
before sending a message. This fixes the problem described in PR 16240
and PR 20877 (ip_id field was returned in host byte order).
o ip_ttl decrement operation in ip_forward() was moved down to make sure
that it does not corrupt the copy of original IP datagram passed later
to icmp_error().
o A copy of original IP datagram in ip_forward() was made a read-write,
independent copy. This fixes the problem I first reported to Garrett
Wollman and Bill Fenner and later put in audit trail of PR 16240:
ip_output() (not always) converts fields of original datagram to network
byte order, but because copy (mcopy) and its original (m) most likely
share the same mbuf cluster, ip_output()'s manipulations on original
also corrupted the copy.
o ip_output() now expects all three fields, ip_len, ip_off and (what is
significant) ip_id in host byte order. It was a headache for years that
ip_id was handled differently. The only compatibility issue here is the
raw IP socket interface with IP_HDRINCL socket option set and a non-zero
ip_id field, but ip.4 manual page was unclear on whether in this case
ip_id field should be in host or network byte order.
o Drop all broadcast and multicast source addresses in tcp_input.
o Enable ICMP_BANDLIM in GENERIC.
o Change default to 200/s from 100/s. This will still stop the attack, but
is conservative enough to do this close to code freeze.
This is not the optimal patch for the problem, but is likely the least
intrusive patch that can be made for this.
Obtained from: Don Lewis and Matt Dillon.
Reviewed by: freebsd-security
pr_input() routines prototype is also changed to support IPSEC and IPV6
chained protocol headers.
Reviewed by: freebsd-arch, cvs-committers
Obtained from: KAME project
respectively logging and dropping ICMP REDIRECT packets.
Note that there is no rate limiting on the log messages, so log_redirect
should be used with caution (preferrably only for debugging purposes).
option not defined the sysctl int value is set to -1 and read-only.
#ifdef KERNEL's added appropriately to wall off visibility of kernel
routines from user code.
Add ICMP_BANDLIM option and 'net.inet.icmp.icmplim' sysctl. If option
is specified in kernel config, icmplim defaults to 100 pps. Setting it
to 0 will disable the feature. This feature limits ICMP error responses
for packets sent to bad tcp or udp ports, which does a lot to help the
machine handle network D.O.S. attacks.
The kernel will report packet rates that exceed the limit at a rate of
one kernel printf per second. There is one issue in regards to the
'tail end' of an attack... the kernel will not output the last report
until some unrelated and valid icmp error packet is return at some
point after the attack is over. This is a minor reporting issue only.
addresses by default.
Add a knob "icmp_bmcastecho" to "rc.network" to allow this
behaviour to be controlled from "rc.conf".
Document the controlling sysctl variable "net.inet.icmp.bmcastecho"
in sysctl(3).
Reviewed by: dg, jkh
Reminded on -hackers by: Steinar Haug <sthaug@nethelp.no>
net.inet.ip.icmp.bmcastecho = 0 by removing the extra check for the
address being a multicast address. The test now relies on the link
layer flags that indicate it was received via multicast. The previous
logic was broken and replied to ICMP echo/timestamp broadcasts even
when the sysctl option disallowed them.
Reviewed by: wollman
potential problems with other automatic-reply ICMPs, but some of them may
depend on broadcast/multicast to operate. (This code can simply be
moved to the `reflect' label to generalize it.)
Don't search for interface addresses matching interface "NULL"
it's likely to cause a page fault..
this can be triggered by the ipfw code rejecting a locally generated
packet (e.g. you decide to make some network unreachable by local users)
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
to TAILQs. Fix places which referenced these for no good reason
that I can see (the references remain, but were fixed to compile
again; they are still questionable).
Move ipip_input() and rsvp_input() prototypes to ip_var.h
Remove unused prototype for rip_ip_input() from ip_var.h
Remove unused variable *opts from rip_output()
*' instead of caddr_t and it isn't optional (it never was). Most of the
netipx (and netns) pr_ctlinput functions abuse the second arg instead of
using the third arg but fixing this is beyond the scope of this round
of changes.
