From f227e3ec3b5cad859ad15666874405e8c1bbc1d4 Mon Sep 17 00:00:00 2001 From: Willy Tarreau Date: Fri, 10 Jul 2020 15:23:19 +0200 Subject: random32: update the net random state on interrupt and activity This modifies the first 32 bits out of the 128 bits of a random CPU's net_rand_state on interrupt or CPU activity to complicate remote observations that could lead to guessing the network RNG's internal state. Note that depending on some network devices' interrupt rate moderation or binding, this re-seeding might happen on every packet or even almost never. In addition, with NOHZ some CPUs might not even get timer interrupts, leaving their local state rarely updated, while they are running networked processes making use of the random state. For this reason, we also perform this update in update_process_times() in order to at least update the state when there is user or system activity, since it's the only case we care about. Reported-by: Amit Klein Suggested-by: Linus Torvalds Cc: Eric Dumazet Cc: "Jason A. Donenfeld" Cc: Andy Lutomirski Cc: Kees Cook Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Signed-off-by: Willy Tarreau Signed-off-by: Linus Torvalds --- include/linux/random.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/random.h') diff --git a/include/linux/random.h b/include/linux/random.h index 45e1f8fa742b..39aaa1f78f9d 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -11,6 +11,7 @@ #include #include #include +#include #include @@ -119,6 +120,8 @@ struct rnd_state { __u32 s1, s2, s3, s4; }; +DECLARE_PER_CPU(struct rnd_state, net_rand_state) __latent_entropy; + u32 prandom_u32_state(struct rnd_state *state); void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes); void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state); -- cgit v1.2.3 From 83bdc7275e6206f560d247be856bceba3e1ed8f2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 29 Jul 2020 19:11:00 -0700 Subject: random32: remove net_rand_state from the latent entropy gcc plugin It turns out that the plugin right now ends up being really unhappy about the change from 'static' to 'extern' storage that happened in commit f227e3ec3b5c ("random32: update the net random state on interrupt and activity"). This is probably a trivial fix for the latent_entropy plugin, but for now, just remove net_rand_state from the list of things the plugin worries about. Reported-by: Stephen Rothwell Cc: Emese Revfy Cc: Kees Cook Cc: Willy Tarreau Signed-off-by: Linus Torvalds --- include/linux/random.h | 2 +- lib/random32.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/random.h') diff --git a/include/linux/random.h b/include/linux/random.h index 39aaa1f78f9d..f310897f051d 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -120,7 +120,7 @@ struct rnd_state { __u32 s1, s2, s3, s4; }; -DECLARE_PER_CPU(struct rnd_state, net_rand_state) __latent_entropy; +DECLARE_PER_CPU(struct rnd_state, net_rand_state); u32 prandom_u32_state(struct rnd_state *state); void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes); diff --git a/lib/random32.c b/lib/random32.c index c4d317be2997..3d749abb9e80 100644 --- a/lib/random32.c +++ b/lib/random32.c @@ -48,7 +48,7 @@ static inline void prandom_state_selftest(void) } #endif -DEFINE_PER_CPU(struct rnd_state, net_rand_state) __latent_entropy; +DEFINE_PER_CPU(struct rnd_state, net_rand_state); /** * prandom_u32_state - seeded pseudo-random number generator. -- cgit v1.2.3 From 1c9df907da83812e4f33b59d3d142c864d9da57f Mon Sep 17 00:00:00 2001 From: Willy Tarreau Date: Thu, 30 Jul 2020 07:59:24 +0200 Subject: random: fix circular include dependency on arm64 after addition of percpu.h MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Daniel Díaz and Kees Cook independently reported that commit f227e3ec3b5c ("random32: update the net random state on interrupt and activity") broke arm64 due to a circular dependency on include files since the addition of percpu.h in random.h. The correct fix would definitely be to move all the prandom32 stuff out of random.h but for backporting, a smaller solution is preferred. This one replaces linux/percpu.h with asm/percpu.h, and this fixes the problem on x86_64, arm64, arm, and mips. Note that moving percpu.h around didn't change anything and that removing it entirely broke differently. When backporting, such options might still be considered if this patch fails to help. [ It turns out that an alternate fix seems to be to just remove the troublesome remove from the arm64 that causes the circular dependency. But we might as well do the whole belt-and-suspenders thing, and minimize inclusion in too. Either will fix the problem, and both are good changes. - Linus ] Reported-by: Daniel Díaz Reported-by: Kees Cook Tested-by: Marc Zyngier Fixes: f227e3ec3b5c Cc: Stephen Rothwell Signed-off-by: Willy Tarreau Signed-off-by: Linus Torvalds --- include/linux/random.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/random.h') diff --git a/include/linux/random.h b/include/linux/random.h index f310897f051d..9ab7443bd91b 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -11,7 +11,7 @@ #include #include #include -#include +#include #include -- cgit v1.2.3