From 2c956a60778cbb6a27e0c7a8a52a91378c90e1d1 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Sun, 8 Jan 2017 13:54:00 +0100 Subject: siphash: add cryptographically secure PRF SipHash is a 64-bit keyed hash function that is actually a cryptographically secure PRF, like HMAC. Except SipHash is super fast, and is meant to be used as a hashtable keyed lookup function, or as a general PRF for short input use cases, such as sequence numbers or RNG chaining. For the first usage: There are a variety of attacks known as "hashtable poisoning" in which an attacker forms some data such that the hash of that data will be the same, and then preceeds to fill up all entries of a hashbucket. This is a realistic and well-known denial-of-service vector. Currently hashtables use jhash, which is fast but not secure, and some kind of rotating key scheme (or none at all, which isn't good). SipHash is meant as a replacement for jhash in these cases. There are a modicum of places in the kernel that are vulnerable to hashtable poisoning attacks, either via userspace vectors or network vectors, and there's not a reliable mechanism inside the kernel at the moment to fix it. The first step toward fixing these issues is actually getting a secure primitive into the kernel for developers to use. Then we can, bit by bit, port things over to it as deemed appropriate. While SipHash is extremely fast for a cryptographically secure function, it is likely a bit slower than the insecure jhash, and so replacements will be evaluated on a case-by-case basis based on whether or not the difference in speed is negligible and whether or not the current jhash usage poses a real security risk. For the second usage: A few places in the kernel are using MD5 or SHA1 for creating secure sequence numbers, syn cookies, port numbers, or fast random numbers. SipHash is a faster and more fitting, and more secure replacement for MD5 in those situations. Replacing MD5 and SHA1 with SipHash for these uses is obvious and straight-forward, and so is submitted along with this patch series. There shouldn't be much of a debate over its efficacy. Dozens of languages are already using this internally for their hash tables and PRFs. Some of the BSDs already use this in their kernels. SipHash is a widely known high-speed solution to a widely known set of problems, and it's time we catch-up. Signed-off-by: Jason A. Donenfeld Reviewed-by: Jean-Philippe Aumasson Cc: Linus Torvalds Cc: Eric Biggers Cc: David Laight Cc: Eric Dumazet Signed-off-by: David S. Miller --- lib/Kconfig.debug | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'lib/Kconfig.debug') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index b06848a104e6..3d2515a770c3 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1819,9 +1819,9 @@ config TEST_HASH tristate "Perform selftest on hash functions" default n help - Enable this option to test the kernel's integer () - and string () hash functions on boot - (or module load). + Enable this option to test the kernel's integer (), + string (), and siphash () + hash functions on boot (or module load). This is intended to help people writing architecture-specific optimized versions. If unsure, say N. -- cgit From 44091d29f2075972aede47ef17e1e70db3d51190 Mon Sep 17 00:00:00 2001 From: Jiri Pirko Date: Fri, 3 Feb 2017 10:29:06 +0100 Subject: lib: Introduce priority array area manager This introduces a infrastructure for management of linear priority areas. Priority order in an array matters, however order of items inside a priority group does not matter. As an initial implementation, L-sort algorithm is used. It is quite trivial. More advanced algorithm called P-sort will be introduced as a follow-up. The infrastructure is prepared for other algos. Alongside this, a testing module is introduced as well. Signed-off-by: Jiri Pirko Signed-off-by: David S. Miller --- lib/Kconfig.debug | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'lib/Kconfig.debug') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 15969abf00a6..433a788500be 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1826,6 +1826,16 @@ config TEST_HASH This is intended to help people writing architecture-specific optimized versions. If unsure, say N. +config TEST_PARMAN + tristate "Perform selftest on priority array manager" + default n + depends on PARMAN + help + Enable this option to test priority array manager on boot + (or module load). + + If unsure, say N. + endmenu # runtime tests config PROVIDE_OHCI1394_DMA_INIT -- cgit