linux/net/sctp/Kconfig
Neil Horman 3c68198e75 sctp: Make hmac algorithm selection for cookie generation dynamic
Currently sctp allows for the optional use of md5 of sha1 hmac algorithms to
generate cookie values when establishing new connections via two build time
config options.  Theres no real reason to make this a static selection.  We can
add a sysctl that allows for the dynamic selection of these algorithms at run
time, with the default value determined by the corresponding crypto library
availability.
This comes in handy when, for example running a system in FIPS mode, where use
of md5 is disallowed, but SHA1 is permitted.

Note: This new sysctl has no corresponding socket option to select the cookie
hmac algorithm.  I chose not to implement that intentionally, as RFC 6458
contains no option for this value, and I opted not to pollute the socket option
namespace.

Change notes:
v2)
	* Updated subject to have the proper sctp prefix as per Dave M.
	* Replaced deafult selection options with new options that allow
	  developers to explicitly select available hmac algs at build time
	  as per suggestion by Vlad Y.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Vlad Yasevich <vyasevich@gmail.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: netdev@vger.kernel.org
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-10-26 02:22:18 -04:00

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#
# SCTP configuration
#
menuconfig IP_SCTP
tristate "The SCTP Protocol (EXPERIMENTAL)"
depends on INET && EXPERIMENTAL
depends on IPV6 || IPV6=n
select CRYPTO
select CRYPTO_HMAC
select CRYPTO_SHA1
select LIBCRC32C
---help---
Stream Control Transmission Protocol
From RFC 2960 <http://www.ietf.org/rfc/rfc2960.txt>.
"SCTP is a reliable transport protocol operating on top of a
connectionless packet network such as IP. It offers the following
services to its users:
-- acknowledged error-free non-duplicated transfer of user data,
-- data fragmentation to conform to discovered path MTU size,
-- sequenced delivery of user messages within multiple streams,
with an option for order-of-arrival delivery of individual user
messages,
-- optional bundling of multiple user messages into a single SCTP
packet, and
-- network-level fault tolerance through supporting of multi-
homing at either or both ends of an association."
To compile this protocol support as a module, choose M here: the
module will be called sctp.
If in doubt, say N.
if IP_SCTP
config NET_SCTPPROBE
tristate "SCTP: Association probing"
depends on PROC_FS && KPROBES
---help---
This module allows for capturing the changes to SCTP association
state in response to incoming packets. It is used for debugging
SCTP congestion control algorithms. If you don't understand
what was just said, you don't need it: say N.
To compile this code as a module, choose M here: the
module will be called sctp_probe.
config SCTP_DBG_MSG
bool "SCTP: Debug messages"
help
If you say Y, this will enable verbose debugging messages.
If unsure, say N. However, if you are running into problems, use
this option to gather detailed trace information
config SCTP_DBG_OBJCNT
bool "SCTP: Debug object counts"
depends on PROC_FS
help
If you say Y, this will enable debugging support for counting the
type of objects that are currently allocated. This is useful for
identifying memory leaks. This debug information can be viewed by
'cat /proc/net/sctp/sctp_dbg_objcnt'
If unsure, say N
config SCTP_COOKIE_HMAC_MD5
bool "Enable optional MD5 hmac cookie generation"
help
Enable optional MD5 hmac based SCTP cookie generation
default y
select CRYPTO_HMAC if SCTP_COOKIE_HMAC_MD5
select CRYPTO_MD5 if SCTP_COOKIE_HMAC_MD5
config SCTP_COOKIE_HMAC_SHA1
bool "Enable optional SHA1 hmac cookie generation"
help
Enable optional SHA1 hmac based SCTP cookie generation
default y
select CRYPTO_HMAC if SCTP_COOKIE_HMAC_SHA1
select CRYPTO_SHA1 if SCTP_COOKIE_HMAC_SHA1
endif # IP_SCTP