From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- drivers/net/wireguard/ratelimiter.c | 223 ++++++++++++++++++++++++++++++++++++ 1 file changed, 223 insertions(+) create mode 100644 drivers/net/wireguard/ratelimiter.c (limited to 'drivers/net/wireguard/ratelimiter.c') diff --git a/drivers/net/wireguard/ratelimiter.c b/drivers/net/wireguard/ratelimiter.c new file mode 100644 index 000000000..2b3867f69 --- /dev/null +++ b/drivers/net/wireguard/ratelimiter.c @@ -0,0 +1,223 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2015-2019 Jason A. Donenfeld . All Rights Reserved. + */ + +#include "ratelimiter.h" +#include +#include +#include +#include + +static struct kmem_cache *entry_cache; +static hsiphash_key_t key; +static spinlock_t table_lock = __SPIN_LOCK_UNLOCKED("ratelimiter_table_lock"); +static DEFINE_MUTEX(init_lock); +static u64 init_refcnt; /* Protected by init_lock, hence not atomic. */ +static atomic_t total_entries = ATOMIC_INIT(0); +static unsigned int max_entries, table_size; +static void wg_ratelimiter_gc_entries(struct work_struct *); +static DECLARE_DEFERRABLE_WORK(gc_work, wg_ratelimiter_gc_entries); +static struct hlist_head *table_v4; +#if IS_ENABLED(CONFIG_IPV6) +static struct hlist_head *table_v6; +#endif + +struct ratelimiter_entry { + u64 last_time_ns, tokens, ip; + void *net; + spinlock_t lock; + struct hlist_node hash; + struct rcu_head rcu; +}; + +enum { + PACKETS_PER_SECOND = 20, + PACKETS_BURSTABLE = 5, + PACKET_COST = NSEC_PER_SEC / PACKETS_PER_SECOND, + TOKEN_MAX = PACKET_COST * PACKETS_BURSTABLE +}; + +static void entry_free(struct rcu_head *rcu) +{ + kmem_cache_free(entry_cache, + container_of(rcu, struct ratelimiter_entry, rcu)); + atomic_dec(&total_entries); +} + +static void entry_uninit(struct ratelimiter_entry *entry) +{ + hlist_del_rcu(&entry->hash); + call_rcu(&entry->rcu, entry_free); +} + +/* Calling this function with a NULL work uninits all entries. */ +static void wg_ratelimiter_gc_entries(struct work_struct *work) +{ + const u64 now = ktime_get_coarse_boottime_ns(); + struct ratelimiter_entry *entry; + struct hlist_node *temp; + unsigned int i; + + for (i = 0; i < table_size; ++i) { + spin_lock(&table_lock); + hlist_for_each_entry_safe(entry, temp, &table_v4[i], hash) { + if (unlikely(!work) || + now - entry->last_time_ns > NSEC_PER_SEC) + entry_uninit(entry); + } +#if IS_ENABLED(CONFIG_IPV6) + hlist_for_each_entry_safe(entry, temp, &table_v6[i], hash) { + if (unlikely(!work) || + now - entry->last_time_ns > NSEC_PER_SEC) + entry_uninit(entry); + } +#endif + spin_unlock(&table_lock); + if (likely(work)) + cond_resched(); + } + if (likely(work)) + queue_delayed_work(system_power_efficient_wq, &gc_work, HZ); +} + +bool wg_ratelimiter_allow(struct sk_buff *skb, struct net *net) +{ + /* We only take the bottom half of the net pointer, so that we can hash + * 3 words in the end. This way, siphash's len param fits into the final + * u32, and we don't incur an extra round. + */ + const u32 net_word = (unsigned long)net; + struct ratelimiter_entry *entry; + struct hlist_head *bucket; + u64 ip; + + if (skb->protocol == htons(ETH_P_IP)) { + ip = (u64 __force)ip_hdr(skb)->saddr; + bucket = &table_v4[hsiphash_2u32(net_word, ip, &key) & + (table_size - 1)]; + } +#if IS_ENABLED(CONFIG_IPV6) + else if (skb->protocol == htons(ETH_P_IPV6)) { + /* Only use 64 bits, so as to ratelimit the whole /64. */ + memcpy(&ip, &ipv6_hdr(skb)->saddr, sizeof(ip)); + bucket = &table_v6[hsiphash_3u32(net_word, ip >> 32, ip, &key) & + (table_size - 1)]; + } +#endif + else + return false; + rcu_read_lock(); + hlist_for_each_entry_rcu(entry, bucket, hash) { + if (entry->net == net && entry->ip == ip) { + u64 now, tokens; + bool ret; + /* Quasi-inspired by nft_limit.c, but this is actually a + * slightly different algorithm. Namely, we incorporate + * the burst as part of the maximum tokens, rather than + * as part of the rate. + */ + spin_lock(&entry->lock); + now = ktime_get_coarse_boottime_ns(); + tokens = min_t(u64, TOKEN_MAX, + entry->tokens + now - + entry->last_time_ns); + entry->last_time_ns = now; + ret = tokens >= PACKET_COST; + entry->tokens = ret ? tokens - PACKET_COST : tokens; + spin_unlock(&entry->lock); + rcu_read_unlock(); + return ret; + } + } + rcu_read_unlock(); + + if (atomic_inc_return(&total_entries) > max_entries) + goto err_oom; + + entry = kmem_cache_alloc(entry_cache, GFP_KERNEL); + if (unlikely(!entry)) + goto err_oom; + + entry->net = net; + entry->ip = ip; + INIT_HLIST_NODE(&entry->hash); + spin_lock_init(&entry->lock); + entry->last_time_ns = ktime_get_coarse_boottime_ns(); + entry->tokens = TOKEN_MAX - PACKET_COST; + spin_lock(&table_lock); + hlist_add_head_rcu(&entry->hash, bucket); + spin_unlock(&table_lock); + return true; + +err_oom: + atomic_dec(&total_entries); + return false; +} + +int wg_ratelimiter_init(void) +{ + mutex_lock(&init_lock); + if (++init_refcnt != 1) + goto out; + + entry_cache = KMEM_CACHE(ratelimiter_entry, 0); + if (!entry_cache) + goto err; + + /* xt_hashlimit.c uses a slightly different algorithm for ratelimiting, + * but what it shares in common is that it uses a massive hashtable. So, + * we borrow their wisdom about good table sizes on different systems + * dependent on RAM. This calculation here comes from there. + */ + table_size = (totalram_pages() > (1U << 30) / PAGE_SIZE) ? 8192 : + max_t(unsigned long, 16, roundup_pow_of_two( + (totalram_pages() << PAGE_SHIFT) / + (1U << 14) / sizeof(struct hlist_head))); + max_entries = table_size * 8; + + table_v4 = kvzalloc_objs(*table_v4, table_size); + if (unlikely(!table_v4)) + goto err_kmemcache; + +#if IS_ENABLED(CONFIG_IPV6) + table_v6 = kvzalloc_objs(*table_v6, table_size); + if (unlikely(!table_v6)) { + kvfree(table_v4); + goto err_kmemcache; + } +#endif + + queue_delayed_work(system_power_efficient_wq, &gc_work, HZ); + get_random_bytes(&key, sizeof(key)); +out: + mutex_unlock(&init_lock); + return 0; + +err_kmemcache: + kmem_cache_destroy(entry_cache); +err: + --init_refcnt; + mutex_unlock(&init_lock); + return -ENOMEM; +} + +void wg_ratelimiter_uninit(void) +{ + mutex_lock(&init_lock); + if (!init_refcnt || --init_refcnt) + goto out; + + cancel_delayed_work_sync(&gc_work); + wg_ratelimiter_gc_entries(NULL); + rcu_barrier(); + kvfree(table_v4); +#if IS_ENABLED(CONFIG_IPV6) + kvfree(table_v6); +#endif + kmem_cache_destroy(entry_cache); +out: + mutex_unlock(&init_lock); +} + +#include "selftest/ratelimiter.c" -- cgit v1.3.1