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32f8807a48
Xin Long says:
====================
sctp: enhancements for the verification tag
This patchset is to address CVE-2021-3772:
A flaw was found in the Linux SCTP stack. A blind attacker may be able to
kill an existing SCTP association through invalid chunks if the attacker
knows the IP-addresses and port numbers being used and the attacker can
send packets with spoofed IP addresses.
This is caused by the missing VTAG verification for the received chunks
and the incorrect vtag for the ABORT used to reply to these invalid
chunks.
This patchset is to go over all processing functions for the received
chunks and do:
1. Make sure sctp_vtag_verify() is called firstly to verify the vtag from
the received chunk and discard this chunk if it fails. With some
exceptions:
a. sctp_sf_do_5_1B_init()/5_2_2_dupinit()/9_2_reshutack(), processing
INIT chunk, as sctphdr vtag is always 0 in INIT chunk.
b. sctp_sf_do_5_2_4_dupcook(), processing dupicate COOKIE_ECHO chunk,
as the vtag verification will be done by sctp_tietags_compare() and
then it takes right actions according to the return.
c. sctp_sf_shut_8_4_5(), processing SHUTDOWN_ACK chunk for cookie_wait
and cookie_echoed state, as RFC demand sending a SHUTDOWN_COMPLETE
even if the vtag verification failed.
d. sctp_sf_ootb(), called in many types of chunks for closed state or
no asoc, as the same reason to c.
2. Always use the vtag from the received INIT chunk to make the response
ABORT in sctp_ootb_pkt_new().
3. Fix the order for some checks and add some missing checks for the
received chunk.
This patch series has been tested with SCTP TAHI testing to make sure no
regression caused on protocol conformance.
====================
Link: https://lore.kernel.org/r/cover.1634730082.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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
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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.
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.