From ce9b362bf6db51a083c4221ef0f93c16cfb1facf Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Fri, 24 Jul 2020 20:14:34 +1000 Subject: rhashtable: Restore RCU marking on rhash_lock_head This patch restores the RCU marking on bucket_table->buckets as it really does need RCU protection. Its removal had led to a fatal bug. Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- lib/rhashtable.c | 35 ++++++++++++++++------------------- 1 file changed, 16 insertions(+), 19 deletions(-) (limited to 'lib') diff --git a/lib/rhashtable.c b/lib/rhashtable.c index 9f6890aedd1a..c949c1e3b87c 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -31,7 +31,7 @@ union nested_table { union nested_table __rcu *table; - struct rhash_lock_head *bucket; + struct rhash_lock_head __rcu *bucket; }; static u32 head_hashfn(struct rhashtable *ht, @@ -222,7 +222,7 @@ static struct bucket_table *rhashtable_last_table(struct rhashtable *ht, } static int rhashtable_rehash_one(struct rhashtable *ht, - struct rhash_lock_head **bkt, + struct rhash_lock_head __rcu **bkt, unsigned int old_hash) { struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht); @@ -275,7 +275,7 @@ static int rhashtable_rehash_chain(struct rhashtable *ht, unsigned int old_hash) { struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht); - struct rhash_lock_head **bkt = rht_bucket_var(old_tbl, old_hash); + struct rhash_lock_head __rcu **bkt = rht_bucket_var(old_tbl, old_hash); int err; if (!bkt) @@ -485,7 +485,7 @@ fail: } static void *rhashtable_lookup_one(struct rhashtable *ht, - struct rhash_lock_head **bkt, + struct rhash_lock_head __rcu **bkt, struct bucket_table *tbl, unsigned int hash, const void *key, struct rhash_head *obj) { @@ -535,12 +535,10 @@ static void *rhashtable_lookup_one(struct rhashtable *ht, return ERR_PTR(-ENOENT); } -static struct bucket_table *rhashtable_insert_one(struct rhashtable *ht, - struct rhash_lock_head **bkt, - struct bucket_table *tbl, - unsigned int hash, - struct rhash_head *obj, - void *data) +static struct bucket_table *rhashtable_insert_one( + struct rhashtable *ht, struct rhash_lock_head __rcu **bkt, + struct bucket_table *tbl, unsigned int hash, struct rhash_head *obj, + void *data) { struct bucket_table *new_tbl; struct rhash_head *head; @@ -591,7 +589,7 @@ static void *rhashtable_try_insert(struct rhashtable *ht, const void *key, { struct bucket_table *new_tbl; struct bucket_table *tbl; - struct rhash_lock_head **bkt; + struct rhash_lock_head __rcu **bkt; unsigned int hash; void *data; @@ -1173,8 +1171,8 @@ void rhashtable_destroy(struct rhashtable *ht) } EXPORT_SYMBOL_GPL(rhashtable_destroy); -struct rhash_lock_head **__rht_bucket_nested(const struct bucket_table *tbl, - unsigned int hash) +struct rhash_lock_head __rcu **__rht_bucket_nested( + const struct bucket_table *tbl, unsigned int hash) { const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *)); unsigned int index = hash & ((1 << tbl->nest) - 1); @@ -1202,10 +1200,10 @@ struct rhash_lock_head **__rht_bucket_nested(const struct bucket_table *tbl, } EXPORT_SYMBOL_GPL(__rht_bucket_nested); -struct rhash_lock_head **rht_bucket_nested(const struct bucket_table *tbl, - unsigned int hash) +struct rhash_lock_head __rcu **rht_bucket_nested( + const struct bucket_table *tbl, unsigned int hash) { - static struct rhash_lock_head *rhnull; + static struct rhash_lock_head __rcu *rhnull; if (!rhnull) INIT_RHT_NULLS_HEAD(rhnull); @@ -1213,9 +1211,8 @@ struct rhash_lock_head **rht_bucket_nested(const struct bucket_table *tbl, } EXPORT_SYMBOL_GPL(rht_bucket_nested); -struct rhash_lock_head **rht_bucket_nested_insert(struct rhashtable *ht, - struct bucket_table *tbl, - unsigned int hash) +struct rhash_lock_head __rcu **rht_bucket_nested_insert( + struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash) { const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *)); unsigned int index = hash & ((1 << tbl->nest) - 1); -- cgit v1.2.3 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 --- drivers/char/random.c | 1 + include/linux/random.h | 3 +++ kernel/time/timer.c | 8 ++++++++ lib/random32.c | 2 +- 4 files changed, 13 insertions(+), 1 deletion(-) (limited to 'lib') diff --git a/drivers/char/random.c b/drivers/char/random.c index 2a41b21623ae..d20ba1b104ca 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1277,6 +1277,7 @@ void add_interrupt_randomness(int irq, int irq_flags) fast_mix(fast_pool); add_interrupt_bench(cycles); + this_cpu_add(net_rand_state.s1, fast_pool->pool[cycles & 3]); if (unlikely(crng_init == 0)) { if ((fast_pool->count >= 64) && 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); diff --git a/kernel/time/timer.c b/kernel/time/timer.c index df1ff803acc4..026ac01af9da 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -43,6 +43,7 @@ #include #include #include +#include #include #include @@ -1742,6 +1743,13 @@ void update_process_times(int user_tick) scheduler_tick(); if (IS_ENABLED(CONFIG_POSIX_TIMERS)) run_posix_cpu_timers(); + + /* The current CPU might make use of net randoms without receiving IRQs + * to renew them often enough. Let's update the net_rand_state from a + * non-constant value that's not affine to the number of calls to make + * sure it's updated when there's some activity (we don't care in idle). + */ + this_cpu_add(net_rand_state.s1, rol32(jiffies, 24) + user_tick); } /** diff --git a/lib/random32.c b/lib/random32.c index 763b920a6206..c4d317be2997 100644 --- a/lib/random32.c +++ b/lib/random32.c @@ -48,7 +48,7 @@ static inline void prandom_state_selftest(void) } #endif -static DEFINE_PER_CPU(struct rnd_state, net_rand_state) __latent_entropy; +DEFINE_PER_CPU(struct rnd_state, net_rand_state) __latent_entropy; /** * prandom_u32_state - seeded pseudo-random number generator. -- 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 'lib') 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