e66515999b
Commit adc176c54722 ("ipv6 addrconf: Implemented enhanced DAD (RFC7527)")
added enhanced DAD with a nonce length of 6 bytes. However, RFC7527
doesn't specify the length of the nonce, other than being 6 + 8*k bytes,
with integer k >= 0 (RFC3971 5.3.2). The current implementation simply
assumes that the nonce will always be 6 bytes, but others systems are
free to choose different sizes.
If another system sends a nonce of different length but with the same 6
bytes prefix, it shouldn't be considered as the same nonce. Thus, check
that the length of the received nonce is the same as the length we sent.
Ugly scapy test script running on veth0:
def loop():
pkt=sniff(iface="veth0", filter="icmp6", count=1)
pkt = pkt[0]
b = bytearray(pkt[Raw].load)
b[1] += 1
b += b'\xde\xad\xbe\xef\xde\xad\xbe\xef'
pkt[Raw].load = bytes(b)
pkt[IPv6].plen += 8
# fixup checksum after modifying the payload
pkt[IPv6].payload.cksum -= 0x3b44
if pkt[IPv6].payload.cksum < 0:
pkt[IPv6].payload.cksum += 0xffff
sendp(pkt, iface="veth0")
This should result in DAD failure for any address added to veth0's peer,
but is currently ignored.
Fixes: adc176c54722 ("ipv6 addrconf: Implemented enhanced DAD (RFC7527)")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.