From: Xin Long <lucien.xin@gmail.com> stable inclusion from stable-v6.6.152 commit 69cba7b704400929aa862c398ca51276603ee085 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/18291 CVE: CVE-2026-74700 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit a12c76a03386e32413ae8eaaefa337e491880632 ] This patch addresses issues with filter counting in block (tcf_block), particularly for software bypass scenarios, by introducing a more accurate mechanism using useswcnt. Previously, filtercnt and skipswcnt were introduced by: Commit 2081fd3445fe ("net: sched: cls_api: add filter counter") and Commit f631ef39d819 ("net: sched: cls_api: add skip_sw counter") filtercnt tracked all tp (tcf_proto) objects added to a block, and skipswcnt counted tp objects with the skipsw attribute set. The problem is: a single tp can contain multiple filters, some with skipsw and others without. The current implementation fails in the case: When the first filter in a tp has skipsw, both skipswcnt and filtercnt are incremented, then adding a second filter without skipsw to the same tp does not modify these counters because tp->counted is already set. This results in bypass software behavior based solely on skipswcnt equaling filtercnt, even when the block includes filters without skipsw. Consequently, filters without skipsw are inadvertently bypassed. To address this, the patch introduces useswcnt in block to explicitly count tp objects containing at least one filter without skipsw. Key changes include: Whenever a filter without skipsw is added, its tp is marked with usesw and counted in useswcnt. tc_run() now uses useswcnt to determine software bypass, eliminating reliance on filtercnt and skipswcnt. This refined approach prevents software bypass for blocks containing mixed filters, ensuring correct behavior in tc_run(). Additionally, as atomic operations on useswcnt ensure thread safety and tp->lock guards access to tp->usesw and tp->counted, the broader lock down_write(&block->cb_lock) is no longer required in tc_new_tfilter(), and this resolves a performance regression caused by the filter counting mechanism during parallel filter insertions. The improvement can be demonstrated using the following script: # cat insert_tc_rules.sh tc qdisc add dev ens1f0np0 ingress for i in $(seq 16); do taskset -c $i tc -b rules_$i.txt & done wait Each of rules_$i.txt files above includes 100000 tc filter rules to a mlx5 driver NIC ens1f0np0. Without this patch: # time sh insert_tc_rules.sh real 0m50.780s user 0m23.556s sys 4m13.032s With this patch: # time sh insert_tc_rules.sh real 0m17.718s user 0m7.807s sys 3m45.050s Fixes: 047f340b36fc ("net: sched: make skip_sw actually skip software") Reported-by: Shuang Li <shuali@redhat.com> Signed-off-by: Xin Long <lucien.xin@gmail.com> Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Reviewed-by: Asbjørn Sloth Tønnesen <ast@fiberby.net> Tested-by: Asbjørn Sloth Tønnesen <ast@fiberby.net> Signed-off-by: David S. Miller <davem@davemloft.net> Stable-dep-of: a347304b2ca1 ("net/sched: cls_api: Always acquire rtnl_lock when destroying locked classifiers") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Li Xiasong <lixiasong1@huawei.com> Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- include/net/pkt_cls.h | 13 +++++++-- include/net/sch_generic.h | 5 ++-- net/core/dev.c | 15 ++++++----- net/sched/cls_api.c | 57 ++++++++++++++++----------------------- net/sched/cls_bpf.c | 2 ++ net/sched/cls_flower.c | 2 ++ net/sched/cls_matchall.c | 2 ++ net/sched/cls_u32.c | 4 +++ 8 files changed, 55 insertions(+), 45 deletions(-) diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h index 0c1a1e366e8e..307478c23322 100644 --- a/include/net/pkt_cls.h +++ b/include/net/pkt_cls.h @@ -73,11 +73,11 @@ static inline bool tcf_block_non_null_shared(struct tcf_block *block) } #ifdef CONFIG_NET_CLS_ACT -DECLARE_STATIC_KEY_FALSE(tcf_bypass_check_needed_key); +DECLARE_STATIC_KEY_FALSE(tcf_sw_enabled_key); static inline bool tcf_block_bypass_sw(struct tcf_block *block) { - return block && block->bypass_wanted; + return block && !atomic_read(&block->useswcnt); } #endif @@ -759,6 +759,15 @@ tc_cls_common_offload_init(struct flow_cls_common_offload *cls_common, cls_common->extack = extack; } +static inline void tcf_proto_update_usesw(struct tcf_proto *tp, u32 flags) +{ + if (tp->usesw) + return; + if (tc_skip_sw(flags) && tc_in_hw(flags)) + return; + tp->usesw = true; +} + #if IS_ENABLED(CONFIG_NET_TC_SKB_EXT) static inline struct tc_skb_ext *tc_skb_ext_alloc(struct sk_buff *skb) { diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index eca7d42af93c..d30eb9ac2c2a 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -440,6 +440,7 @@ struct tcf_proto { spinlock_t lock; bool deleting; bool counted; + bool usesw; refcount_t refcnt; struct rcu_head rcu; struct hlist_node destroy_ht_node; @@ -488,9 +489,7 @@ struct tcf_block { struct flow_block flow_block; struct list_head owner_list; bool keep_dst; - bool bypass_wanted; - atomic_t filtercnt; /* Number of filters */ - atomic_t skipswcnt; /* Number of skip_sw filters */ + atomic_t useswcnt; atomic_t offloadcnt; /* Number of oddloaded filters */ unsigned int nooffloaddevcnt; /* Number of devs unable to do offload */ unsigned int lockeddevcnt; /* Number of devs that require rtnl lock. */ diff --git a/net/core/dev.c b/net/core/dev.c index ab77d212faef..330cbe059273 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2158,8 +2158,8 @@ EXPORT_SYMBOL_GPL(net_dec_egress_queue); #endif #ifdef CONFIG_NET_CLS_ACT -DEFINE_STATIC_KEY_FALSE(tcf_bypass_check_needed_key); -EXPORT_SYMBOL(tcf_bypass_check_needed_key); +DEFINE_STATIC_KEY_FALSE(tcf_sw_enabled_key); +EXPORT_SYMBOL(tcf_sw_enabled_key); #endif DEFINE_STATIC_KEY_FALSE(netstamp_needed_key); @@ -4060,10 +4060,13 @@ static int tc_run(struct tcx_entry *entry, struct sk_buff *skb) if (!miniq) return ret; - if (static_branch_unlikely(&tcf_bypass_check_needed_key)) { - if (tcf_block_bypass_sw(miniq->block)) - return ret; - } + /* Global bypass */ + if (!static_branch_likely(&tcf_sw_enabled_key)) + return ret; + + /* Block-wise bypass */ + if (tcf_block_bypass_sw(miniq->block)) + return ret; tc_skb_cb(skb)->mru = 0; tc_skb_cb(skb)->post_ct = false; diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index 1eedeaf42729..f107afdd36bb 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -390,6 +390,7 @@ static struct tcf_proto *tcf_proto_create(const char *kind, u32 protocol, tp->protocol = protocol; tp->prio = prio; tp->chain = chain; + tp->usesw = !tp->ops->reoffload; spin_lock_init(&tp->lock); refcount_set(&tp->refcnt, 1); @@ -410,39 +411,31 @@ static void tcf_proto_get(struct tcf_proto *tp) refcount_inc(&tp->refcnt); } -static void tcf_maintain_bypass(struct tcf_block *block) +static void tcf_proto_count_usesw(struct tcf_proto *tp, bool add) { - int filtercnt = atomic_read(&block->filtercnt); - int skipswcnt = atomic_read(&block->skipswcnt); - bool bypass_wanted = filtercnt > 0 && filtercnt == skipswcnt; - - if (bypass_wanted != block->bypass_wanted) { #ifdef CONFIG_NET_CLS_ACT - if (bypass_wanted) - static_branch_inc(&tcf_bypass_check_needed_key); - else - static_branch_dec(&tcf_bypass_check_needed_key); -#endif - block->bypass_wanted = bypass_wanted; + struct tcf_block *block = tp->chain->block; + bool counted = false; + + if (!add) { + if (tp->usesw && tp->counted) { + if (!atomic_dec_return(&block->useswcnt)) + static_branch_dec(&tcf_sw_enabled_key); + tp->counted = false; + } + return; } -} - -static void tcf_block_filter_cnt_update(struct tcf_block *block, bool *counted, bool add) -{ - lockdep_assert_not_held(&block->cb_lock); - down_write(&block->cb_lock); - if (*counted != add) { - if (add) { - atomic_inc(&block->filtercnt); - *counted = true; - } else { - atomic_dec(&block->filtercnt); - *counted = false; - } + spin_lock(&tp->lock); + if (tp->usesw && !tp->counted) { + counted = true; + tp->counted = true; } - tcf_maintain_bypass(block); - up_write(&block->cb_lock); + spin_unlock(&tp->lock); + + if (counted && atomic_inc_return(&block->useswcnt) == 1) + static_branch_inc(&tcf_sw_enabled_key); +#endif } static void tcf_chain_put(struct tcf_chain *chain); @@ -451,7 +444,7 @@ static void tcf_proto_destroy(struct tcf_proto *tp, bool rtnl_held, bool sig_destroy, struct netlink_ext_ack *extack) { tp->ops->destroy(tp, rtnl_held, extack); - tcf_block_filter_cnt_update(tp->chain->block, &tp->counted, false); + tcf_proto_count_usesw(tp, false); if (sig_destroy) tcf_proto_signal_destroyed(tp->chain, tp); tcf_chain_put(tp->chain); @@ -2393,7 +2386,7 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n, tfilter_notify(net, skb, n, tp, block, q, parent, fh, RTM_NEWTFILTER, false, rtnl_held, extack); tfilter_put(tp, fh); - tcf_block_filter_cnt_update(block, &tp->counted, true); + tcf_proto_count_usesw(tp, true); /* q pointer is NULL for shared blocks */ if (q) q->flags &= ~TCQ_F_CAN_BYPASS; @@ -3515,8 +3508,6 @@ static void tcf_block_offload_inc(struct tcf_block *block, u32 *flags) if (*flags & TCA_CLS_FLAGS_IN_HW) return; *flags |= TCA_CLS_FLAGS_IN_HW; - if (tc_skip_sw(*flags)) - atomic_inc(&block->skipswcnt); atomic_inc(&block->offloadcnt); } @@ -3525,8 +3516,6 @@ static void tcf_block_offload_dec(struct tcf_block *block, u32 *flags) if (!(*flags & TCA_CLS_FLAGS_IN_HW)) return; *flags &= ~TCA_CLS_FLAGS_IN_HW; - if (tc_skip_sw(*flags)) - atomic_dec(&block->skipswcnt); atomic_dec(&block->offloadcnt); } diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c index d5a5dffcd6f9..cede21257d27 100644 --- a/net/sched/cls_bpf.c +++ b/net/sched/cls_bpf.c @@ -509,6 +509,8 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, if (!tc_in_hw(prog->gen_flags)) prog->gen_flags |= TCA_CLS_FLAGS_NOT_IN_HW; + tcf_proto_update_usesw(tp, prog->gen_flags); + if (oldprog) { idr_replace(&head->handle_idr, prog, handle); list_replace_rcu(&oldprog->link, &prog->link); diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c index b00e491e8130..4fc59af6696e 100644 --- a/net/sched/cls_flower.c +++ b/net/sched/cls_flower.c @@ -2374,6 +2374,8 @@ static int fl_change(struct net *net, struct sk_buff *in_skb, if (!tc_in_hw(fnew->flags)) fnew->flags |= TCA_CLS_FLAGS_NOT_IN_HW; + tcf_proto_update_usesw(tp, fnew->flags); + spin_lock(&tp->lock); /* tp was deleted concurrently. -EAGAIN will cause caller to lookup diff --git a/net/sched/cls_matchall.c b/net/sched/cls_matchall.c index c4ed11df6254..e8353b27c8c4 100644 --- a/net/sched/cls_matchall.c +++ b/net/sched/cls_matchall.c @@ -228,6 +228,8 @@ static int mall_change(struct net *net, struct sk_buff *in_skb, if (!tc_in_hw(new->flags)) new->flags |= TCA_CLS_FLAGS_NOT_IN_HW; + tcf_proto_update_usesw(tp, new->flags); + *arg = head; rcu_assign_pointer(tp->root, new); return 0; diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c index 3e2418339850..202c3acc23b5 100644 --- a/net/sched/cls_u32.c +++ b/net/sched/cls_u32.c @@ -950,6 +950,8 @@ static int u32_change(struct net *net, struct sk_buff *in_skb, if (!tc_in_hw(new->flags)) new->flags |= TCA_CLS_FLAGS_NOT_IN_HW; + tcf_proto_update_usesw(tp, new->flags); + u32_replace_knode(tp, tp_c, new); tcf_unbind_filter(tp, &n->res); tcf_exts_get_net(&n->exts); @@ -1170,6 +1172,8 @@ static int u32_change(struct net *net, struct sk_buff *in_skb, if (!tc_in_hw(n->flags)) n->flags |= TCA_CLS_FLAGS_NOT_IN_HW; + tcf_proto_update_usesw(tp, n->flags); + ins = &ht->ht[TC_U32_HASH(handle)]; for (pins = rtnl_dereference(*ins); pins; ins = &pins->next, pins = rtnl_dereference(*ins)) -- 2.25.1