diff options
Diffstat (limited to 'change_prng.patch')
| -rw-r--r-- | change_prng.patch | 88 |
1 files changed, 76 insertions, 12 deletions
diff --git a/change_prng.patch b/change_prng.patch index 472a39cd8ee6..e44f9355f45f 100644 --- a/change_prng.patch +++ b/change_prng.patch @@ -1,15 +1,17 @@ -commit ca7beb741b4708e7f2cb2e3c33aafc11b560cb59 -Author: Narrat <autumn-wind@web.de> -Date: Tue Apr 4 22:19:53 2017 +0200 - - Replace srand()/rand() combo with getrandom() - - This requires glibc-2.25. - - Reason for the move: The time based initialization is a security issue. - Additionally is the rand() RNG not the best one out there. - - The newly getentropy/getrandom() from glibc uses for random numbers /dev/(u)random, which are a better choice. +From ca7beb741b4708e7f2cb2e3c33aafc11b560cb59 Mon Sep 17 00:00:00 2001 +From: Narrat <autumn-wind@web.de> +Date: Tue, 4 Apr 2017 22:19:53 +0200 +Subject: [PATCH 1/2] Replace srand()/rand() combo with getrandom() + +This requires glibc-2.25. + +Reason for the move: The time based initialization is a security issue. +Additionally is the rand() RNG not the best one out there. + +The newly getentropy/getrandom() from glibc uses for random numbers /dev/(u)random, which are a better choice. +--- + src/correcthorse.c | 15 ++++++++------- + 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/src/correcthorse.c b/src/correcthorse.c index 506e8db..77c8a39 100644 @@ -49,3 +51,65 @@ index 506e8db..77c8a39 100644 } static void rand_perm(size_t *dest, size_t n) +-- +2.16.1 + + +From 77cd9e1d5d6f9d247f3af733d36f4835f621cf4a Mon Sep 17 00:00:00 2001 +From: Max Bruckner <max@maxbruckner.de> +Date: Thu, 1 Feb 2018 21:54:56 +0100 +Subject: [PATCH 2/2] Make random numbers uniformly distributed. + +--- + src/correcthorse.c | 26 ++++++++++++++++++-------- + 1 file changed, 18 insertions(+), 8 deletions(-) + +diff --git a/src/correcthorse.c b/src/correcthorse.c +index 77c8a39..ac7ca45 100644 +--- a/src/correcthorse.c ++++ b/src/correcthorse.c +@@ -14,6 +14,7 @@ + #include <unistd.h> + #include <string.h> + #include <ctype.h> ++#include <stdint.h> + #include <sys/random.h> + + #ifdef _GNU_SOURCE +@@ -30,16 +31,25 @@ static void print_version(char *argv0); + + static size_t rand_index(size_t n) + { +- unsigned long seed_feed[1]; +- int ret=0; ++ size_t random_number = 0; ++ size_t max = SIZE_MAX - (SIZE_MAX % n); ++ ssize_t written = 0; + +- ret = getrandom(seed_feed, sizeof(long), 0); +- if (ret <= 0) { +- fprintf(stderr, "getrandom() returned %d: ", ret); +- perror(""); +- } ++ /* discard values that are in the last section of the ++ * range of SIZE_MAX that would be cut off by the modulo ++ * operator. This way we get a uniformly distributed random ++ * number without small bias. */ ++ do ++ { ++ written = getrandom(&random_number, sizeof(size_t), 0); ++ if (written != sizeof(size_t)) ++ { ++ fprintf(stderr, "getrandom() returned %d: ", (int)written); ++ perror(""); ++ } ++ } while (random_number > max); + +- return *seed_feed % n; ++ return random_number % n; + } + + static void rand_perm(size_t *dest, size_t n) +-- +2.16.1 + |