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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 <Jason@zx2c4.com> Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-08 13:54:00 +01:00
/* Test cases for siphash.c
*
* Copyright (C) 2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*
* This file is provided under a dual BSD/GPLv2 license.
*
* SipHash: a fast short-input PRF
* https://131002.net/siphash/
*
siphash: implement HalfSipHash1-3 for hash tables HalfSipHash, or hsiphash, is a shortened version of SipHash, which generates 32-bit outputs using a weaker 64-bit key. It has *much* lower security margins, and shouldn't be used for anything too sensitive, but it could be used as a hashtable key function replacement, if the output is never exposed, and if the security requirement is not too high. The goal is to make this something that performance-critical jhash users would be willing to use. On 64-bit machines, HalfSipHash1-3 is slower than SipHash1-3, so we alias SipHash1-3 to HalfSipHash1-3 on those systems. 64-bit x86_64: [ 0.509409] test_siphash: SipHash2-4 cycles: 4049181 [ 0.510650] test_siphash: SipHash1-3 cycles: 2512884 [ 0.512205] test_siphash: HalfSipHash1-3 cycles: 3429920 [ 0.512904] test_siphash: JenkinsHash cycles: 978267 So, we map hsiphash() -> SipHash1-3 32-bit x86: [ 0.509868] test_siphash: SipHash2-4 cycles: 14812892 [ 0.513601] test_siphash: SipHash1-3 cycles: 9510710 [ 0.515263] test_siphash: HalfSipHash1-3 cycles: 3856157 [ 0.515952] test_siphash: JenkinsHash cycles: 1148567 So, we map hsiphash() -> HalfSipHash1-3 hsiphash() is roughly 3 times slower than jhash(), but comes with a considerable security improvement. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-08 13:54:01 +01:00
* This implementation is specifically for SipHash2-4 for a secure PRF
* and HalfSipHash1-3/SipHash1-3 for an insecure PRF only suitable for
* hashtables.
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 <Jason@zx2c4.com> Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-08 13:54:00 +01:00
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/siphash.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/module.h>
siphash: implement HalfSipHash1-3 for hash tables HalfSipHash, or hsiphash, is a shortened version of SipHash, which generates 32-bit outputs using a weaker 64-bit key. It has *much* lower security margins, and shouldn't be used for anything too sensitive, but it could be used as a hashtable key function replacement, if the output is never exposed, and if the security requirement is not too high. The goal is to make this something that performance-critical jhash users would be willing to use. On 64-bit machines, HalfSipHash1-3 is slower than SipHash1-3, so we alias SipHash1-3 to HalfSipHash1-3 on those systems. 64-bit x86_64: [ 0.509409] test_siphash: SipHash2-4 cycles: 4049181 [ 0.510650] test_siphash: SipHash1-3 cycles: 2512884 [ 0.512205] test_siphash: HalfSipHash1-3 cycles: 3429920 [ 0.512904] test_siphash: JenkinsHash cycles: 978267 So, we map hsiphash() -> SipHash1-3 32-bit x86: [ 0.509868] test_siphash: SipHash2-4 cycles: 14812892 [ 0.513601] test_siphash: SipHash1-3 cycles: 9510710 [ 0.515263] test_siphash: HalfSipHash1-3 cycles: 3856157 [ 0.515952] test_siphash: JenkinsHash cycles: 1148567 So, we map hsiphash() -> HalfSipHash1-3 hsiphash() is roughly 3 times slower than jhash(), but comes with a considerable security improvement. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-08 13:54:01 +01:00
/* Test vectors taken from reference source available at:
* https://github.com/veorq/SipHash
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 <Jason@zx2c4.com> Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-08 13:54:00 +01:00
*/
static const siphash_key_t test_key_siphash =
{{ 0x0706050403020100ULL, 0x0f0e0d0c0b0a0908ULL }};
static const u64 test_vectors_siphash[64] = {
0x726fdb47dd0e0e31ULL, 0x74f839c593dc67fdULL, 0x0d6c8009d9a94f5aULL,
0x85676696d7fb7e2dULL, 0xcf2794e0277187b7ULL, 0x18765564cd99a68dULL,
0xcbc9466e58fee3ceULL, 0xab0200f58b01d137ULL, 0x93f5f5799a932462ULL,
0x9e0082df0ba9e4b0ULL, 0x7a5dbbc594ddb9f3ULL, 0xf4b32f46226bada7ULL,
0x751e8fbc860ee5fbULL, 0x14ea5627c0843d90ULL, 0xf723ca908e7af2eeULL,
0xa129ca6149be45e5ULL, 0x3f2acc7f57c29bdbULL, 0x699ae9f52cbe4794ULL,
0x4bc1b3f0968dd39cULL, 0xbb6dc91da77961bdULL, 0xbed65cf21aa2ee98ULL,
0xd0f2cbb02e3b67c7ULL, 0x93536795e3a33e88ULL, 0xa80c038ccd5ccec8ULL,
0xb8ad50c6f649af94ULL, 0xbce192de8a85b8eaULL, 0x17d835b85bbb15f3ULL,
0x2f2e6163076bcfadULL, 0xde4daaaca71dc9a5ULL, 0xa6a2506687956571ULL,
0xad87a3535c49ef28ULL, 0x32d892fad841c342ULL, 0x7127512f72f27cceULL,
0xa7f32346f95978e3ULL, 0x12e0b01abb051238ULL, 0x15e034d40fa197aeULL,
0x314dffbe0815a3b4ULL, 0x027990f029623981ULL, 0xcadcd4e59ef40c4dULL,
0x9abfd8766a33735cULL, 0x0e3ea96b5304a7d0ULL, 0xad0c42d6fc585992ULL,
0x187306c89bc215a9ULL, 0xd4a60abcf3792b95ULL, 0xf935451de4f21df2ULL,
0xa9538f0419755787ULL, 0xdb9acddff56ca510ULL, 0xd06c98cd5c0975ebULL,
0xe612a3cb9ecba951ULL, 0xc766e62cfcadaf96ULL, 0xee64435a9752fe72ULL,
0xa192d576b245165aULL, 0x0a8787bf8ecb74b2ULL, 0x81b3e73d20b49b6fULL,
0x7fa8220ba3b2eceaULL, 0x245731c13ca42499ULL, 0xb78dbfaf3a8d83bdULL,
0xea1ad565322a1a0bULL, 0x60e61c23a3795013ULL, 0x6606d7e446282b93ULL,
0x6ca4ecb15c5f91e1ULL, 0x9f626da15c9625f3ULL, 0xe51b38608ef25f57ULL,
0x958a324ceb064572ULL
};
siphash: implement HalfSipHash1-3 for hash tables HalfSipHash, or hsiphash, is a shortened version of SipHash, which generates 32-bit outputs using a weaker 64-bit key. It has *much* lower security margins, and shouldn't be used for anything too sensitive, but it could be used as a hashtable key function replacement, if the output is never exposed, and if the security requirement is not too high. The goal is to make this something that performance-critical jhash users would be willing to use. On 64-bit machines, HalfSipHash1-3 is slower than SipHash1-3, so we alias SipHash1-3 to HalfSipHash1-3 on those systems. 64-bit x86_64: [ 0.509409] test_siphash: SipHash2-4 cycles: 4049181 [ 0.510650] test_siphash: SipHash1-3 cycles: 2512884 [ 0.512205] test_siphash: HalfSipHash1-3 cycles: 3429920 [ 0.512904] test_siphash: JenkinsHash cycles: 978267 So, we map hsiphash() -> SipHash1-3 32-bit x86: [ 0.509868] test_siphash: SipHash2-4 cycles: 14812892 [ 0.513601] test_siphash: SipHash1-3 cycles: 9510710 [ 0.515263] test_siphash: HalfSipHash1-3 cycles: 3856157 [ 0.515952] test_siphash: JenkinsHash cycles: 1148567 So, we map hsiphash() -> HalfSipHash1-3 hsiphash() is roughly 3 times slower than jhash(), but comes with a considerable security improvement. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-08 13:54:01 +01:00
#if BITS_PER_LONG == 64
static const hsiphash_key_t test_key_hsiphash =
{{ 0x0706050403020100ULL, 0x0f0e0d0c0b0a0908ULL }};
static const u32 test_vectors_hsiphash[64] = {
0x050fc4dcU, 0x7d57ca93U, 0x4dc7d44dU,
0xe7ddf7fbU, 0x88d38328U, 0x49533b67U,
0xc59f22a7U, 0x9bb11140U, 0x8d299a8eU,
0x6c063de4U, 0x92ff097fU, 0xf94dc352U,
0x57b4d9a2U, 0x1229ffa7U, 0xc0f95d34U,
0x2a519956U, 0x7d908b66U, 0x63dbd80cU,
0xb473e63eU, 0x8d297d1cU, 0xa6cce040U,
0x2b45f844U, 0xa320872eU, 0xdae6c123U,
0x67349c8cU, 0x705b0979U, 0xca9913a5U,
0x4ade3b35U, 0xef6cd00dU, 0x4ab1e1f4U,
0x43c5e663U, 0x8c21d1bcU, 0x16a7b60dU,
0x7a8ff9bfU, 0x1f2a753eU, 0xbf186b91U,
0xada26206U, 0xa3c33057U, 0xae3a36a1U,
0x7b108392U, 0x99e41531U, 0x3f1ad944U,
0xc8138825U, 0xc28949a6U, 0xfaf8876bU,
0x9f042196U, 0x68b1d623U, 0x8b5114fdU,
0xdf074c46U, 0x12cc86b3U, 0x0a52098fU,
0x9d292f9aU, 0xa2f41f12U, 0x43a71ed0U,
0x73f0bce6U, 0x70a7e980U, 0x243c6d75U,
0xfdb71513U, 0xa67d8a08U, 0xb7e8f148U,
0xf7a644eeU, 0x0f1837f2U, 0x4b6694e0U,
0xb7bbb3a8U
};
#else
static const hsiphash_key_t test_key_hsiphash =
{{ 0x03020100U, 0x07060504U }};
static const u32 test_vectors_hsiphash[64] = {
0x5814c896U, 0xe7e864caU, 0xbc4b0e30U,
0x01539939U, 0x7e059ea6U, 0x88e3d89bU,
0xa0080b65U, 0x9d38d9d6U, 0x577999b1U,
0xc839caedU, 0xe4fa32cfU, 0x959246eeU,
0x6b28096cU, 0x66dd9cd6U, 0x16658a7cU,
0xd0257b04U, 0x8b31d501U, 0x2b1cd04bU,
0x06712339U, 0x522aca67U, 0x911bb605U,
0x90a65f0eU, 0xf826ef7bU, 0x62512debU,
0x57150ad7U, 0x5d473507U, 0x1ec47442U,
0xab64afd3U, 0x0a4100d0U, 0x6d2ce652U,
0x2331b6a3U, 0x08d8791aU, 0xbc6dda8dU,
0xe0f6c934U, 0xb0652033U, 0x9b9851ccU,
0x7c46fb7fU, 0x732ba8cbU, 0xf142997aU,
0xfcc9aa1bU, 0x05327eb2U, 0xe110131cU,
0xf9e5e7c0U, 0xa7d708a6U, 0x11795ab1U,
0x65671619U, 0x9f5fff91U, 0xd89c5267U,
0x007783ebU, 0x95766243U, 0xab639262U,
0x9c7e1390U, 0xc368dda6U, 0x38ddc455U,
0xfa13d379U, 0x979ea4e8U, 0x53ecd77eU,
0x2ee80657U, 0x33dbb66aU, 0xae3f0577U,
0x88b4c4ccU, 0x3e7f480bU, 0x74c1ebf8U,
0x87178304U
};
#endif
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 <Jason@zx2c4.com> Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-08 13:54:00 +01:00
static int __init siphash_test_init(void)
{
u8 in[64] __aligned(SIPHASH_ALIGNMENT);
u8 in_unaligned[65] __aligned(SIPHASH_ALIGNMENT);
u8 i;
int ret = 0;
for (i = 0; i < 64; ++i) {
in[i] = i;
in_unaligned[i + 1] = i;
if (siphash(in, i, &test_key_siphash) !=
test_vectors_siphash[i]) {
pr_info("siphash self-test aligned %u: FAIL\n", i + 1);
ret = -EINVAL;
}
if (siphash(in_unaligned + 1, i, &test_key_siphash) !=
test_vectors_siphash[i]) {
pr_info("siphash self-test unaligned %u: FAIL\n", i + 1);
ret = -EINVAL;
}
siphash: implement HalfSipHash1-3 for hash tables HalfSipHash, or hsiphash, is a shortened version of SipHash, which generates 32-bit outputs using a weaker 64-bit key. It has *much* lower security margins, and shouldn't be used for anything too sensitive, but it could be used as a hashtable key function replacement, if the output is never exposed, and if the security requirement is not too high. The goal is to make this something that performance-critical jhash users would be willing to use. On 64-bit machines, HalfSipHash1-3 is slower than SipHash1-3, so we alias SipHash1-3 to HalfSipHash1-3 on those systems. 64-bit x86_64: [ 0.509409] test_siphash: SipHash2-4 cycles: 4049181 [ 0.510650] test_siphash: SipHash1-3 cycles: 2512884 [ 0.512205] test_siphash: HalfSipHash1-3 cycles: 3429920 [ 0.512904] test_siphash: JenkinsHash cycles: 978267 So, we map hsiphash() -> SipHash1-3 32-bit x86: [ 0.509868] test_siphash: SipHash2-4 cycles: 14812892 [ 0.513601] test_siphash: SipHash1-3 cycles: 9510710 [ 0.515263] test_siphash: HalfSipHash1-3 cycles: 3856157 [ 0.515952] test_siphash: JenkinsHash cycles: 1148567 So, we map hsiphash() -> HalfSipHash1-3 hsiphash() is roughly 3 times slower than jhash(), but comes with a considerable security improvement. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-08 13:54:01 +01:00
if (hsiphash(in, i, &test_key_hsiphash) !=
test_vectors_hsiphash[i]) {
pr_info("hsiphash self-test aligned %u: FAIL\n", i + 1);
ret = -EINVAL;
}
if (hsiphash(in_unaligned + 1, i, &test_key_hsiphash) !=
test_vectors_hsiphash[i]) {
pr_info("hsiphash self-test unaligned %u: FAIL\n", i + 1);
ret = -EINVAL;
}
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 <Jason@zx2c4.com> Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-08 13:54:00 +01:00
}
if (siphash_1u64(0x0706050403020100ULL, &test_key_siphash) !=
test_vectors_siphash[8]) {
pr_info("siphash self-test 1u64: FAIL\n");
ret = -EINVAL;
}
if (siphash_2u64(0x0706050403020100ULL, 0x0f0e0d0c0b0a0908ULL,
&test_key_siphash) != test_vectors_siphash[16]) {
pr_info("siphash self-test 2u64: FAIL\n");
ret = -EINVAL;
}
if (siphash_3u64(0x0706050403020100ULL, 0x0f0e0d0c0b0a0908ULL,
0x1716151413121110ULL, &test_key_siphash) !=
test_vectors_siphash[24]) {
pr_info("siphash self-test 3u64: FAIL\n");
ret = -EINVAL;
}
if (siphash_4u64(0x0706050403020100ULL, 0x0f0e0d0c0b0a0908ULL,
0x1716151413121110ULL, 0x1f1e1d1c1b1a1918ULL,
&test_key_siphash) != test_vectors_siphash[32]) {
pr_info("siphash self-test 4u64: FAIL\n");
ret = -EINVAL;
}
if (siphash_1u32(0x03020100U, &test_key_siphash) !=
test_vectors_siphash[4]) {
pr_info("siphash self-test 1u32: FAIL\n");
ret = -EINVAL;
}
if (siphash_2u32(0x03020100U, 0x07060504U, &test_key_siphash) !=
test_vectors_siphash[8]) {
pr_info("siphash self-test 2u32: FAIL\n");
ret = -EINVAL;
}
if (siphash_3u32(0x03020100U, 0x07060504U,
0x0b0a0908U, &test_key_siphash) !=
test_vectors_siphash[12]) {
pr_info("siphash self-test 3u32: FAIL\n");
ret = -EINVAL;
}
if (siphash_4u32(0x03020100U, 0x07060504U,
0x0b0a0908U, 0x0f0e0d0cU, &test_key_siphash) !=
test_vectors_siphash[16]) {
pr_info("siphash self-test 4u32: FAIL\n");
ret = -EINVAL;
}
siphash: implement HalfSipHash1-3 for hash tables HalfSipHash, or hsiphash, is a shortened version of SipHash, which generates 32-bit outputs using a weaker 64-bit key. It has *much* lower security margins, and shouldn't be used for anything too sensitive, but it could be used as a hashtable key function replacement, if the output is never exposed, and if the security requirement is not too high. The goal is to make this something that performance-critical jhash users would be willing to use. On 64-bit machines, HalfSipHash1-3 is slower than SipHash1-3, so we alias SipHash1-3 to HalfSipHash1-3 on those systems. 64-bit x86_64: [ 0.509409] test_siphash: SipHash2-4 cycles: 4049181 [ 0.510650] test_siphash: SipHash1-3 cycles: 2512884 [ 0.512205] test_siphash: HalfSipHash1-3 cycles: 3429920 [ 0.512904] test_siphash: JenkinsHash cycles: 978267 So, we map hsiphash() -> SipHash1-3 32-bit x86: [ 0.509868] test_siphash: SipHash2-4 cycles: 14812892 [ 0.513601] test_siphash: SipHash1-3 cycles: 9510710 [ 0.515263] test_siphash: HalfSipHash1-3 cycles: 3856157 [ 0.515952] test_siphash: JenkinsHash cycles: 1148567 So, we map hsiphash() -> HalfSipHash1-3 hsiphash() is roughly 3 times slower than jhash(), but comes with a considerable security improvement. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-08 13:54:01 +01:00
if (hsiphash_1u32(0x03020100U, &test_key_hsiphash) !=
test_vectors_hsiphash[4]) {
pr_info("hsiphash self-test 1u32: FAIL\n");
ret = -EINVAL;
}
if (hsiphash_2u32(0x03020100U, 0x07060504U, &test_key_hsiphash) !=
test_vectors_hsiphash[8]) {
pr_info("hsiphash self-test 2u32: FAIL\n");
ret = -EINVAL;
}
if (hsiphash_3u32(0x03020100U, 0x07060504U,
0x0b0a0908U, &test_key_hsiphash) !=
test_vectors_hsiphash[12]) {
pr_info("hsiphash self-test 3u32: FAIL\n");
ret = -EINVAL;
}
if (hsiphash_4u32(0x03020100U, 0x07060504U,
0x0b0a0908U, 0x0f0e0d0cU, &test_key_hsiphash) !=
test_vectors_hsiphash[16]) {
pr_info("hsiphash self-test 4u32: FAIL\n");
ret = -EINVAL;
}
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 <Jason@zx2c4.com> Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-08 13:54:00 +01:00
if (!ret)
pr_info("self-tests: pass\n");
return ret;
}
static void __exit siphash_test_exit(void)
{
}
module_init(siphash_test_init);
module_exit(siphash_test_exit);
MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>");
MODULE_LICENSE("Dual BSD/GPL");
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