From c353e8983e0dea5dbba7789033326e1ad34135b7 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Thu, 20 Mar 2025 19:22:38 +0100 Subject: [PATCH] net: introduce per netns packet chains Currently network taps unbound to any interface are linked in the global ptype_all list, affecting the performance in all the network namespaces. Add per netns ptypes chains, so that in the mentioned case only the netns owning the packet socket(s) is affected. While at that drop the global ptype_all list: no in kernel user registers a tap on "any" type without specifying either the target device or the target namespace (and IMHO doing that would not make any sense). Note that this adds a conditional in the fast path (to check for per netns ptype_specific list) and increases the dataset size by a cacheline (owing the per netns lists). Reviewed-by: Sabrina Dubroca Signed-off-by: Paolo Abeni Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/ae405f98875ee87f8150c460ad162de7e466f8a7.1742494826.git.pabeni@redhat.com Signed-off-by: Jakub Kicinski --- include/linux/netdevice.h | 12 ++++++++- include/net/hotdata.h | 1 - include/net/net_namespace.h | 3 +++ net/core/dev.c | 53 ++++++++++++++++++++++++++++--------- net/core/hotdata.c | 1 - net/core/net-procfs.c | 28 +++++++++++++++----- net/core/net_namespace.c | 2 ++ 7 files changed, 78 insertions(+), 22 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 0c5b1f7f8f3a..f22cca7c03ad 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -4278,7 +4278,17 @@ static __always_inline int ____dev_forward_skb(struct net_device *dev, return 0; } -bool dev_nit_active(struct net_device *dev); +bool dev_nit_active_rcu(const struct net_device *dev); +static inline bool dev_nit_active(const struct net_device *dev) +{ + bool ret; + + rcu_read_lock(); + ret = dev_nit_active_rcu(dev); + rcu_read_unlock(); + return ret; +} + void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev); static inline void __dev_put(struct net_device *dev) diff --git a/include/net/hotdata.h b/include/net/hotdata.h index 30e9570beb2a..fda94b2647ff 100644 --- a/include/net/hotdata.h +++ b/include/net/hotdata.h @@ -23,7 +23,6 @@ struct net_hotdata { struct net_offload udpv6_offload; #endif struct list_head offload_base; - struct list_head ptype_all; struct kmem_cache *skbuff_cache; struct kmem_cache *skbuff_fclone_cache; struct kmem_cache *skb_small_head_cache; diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index f467a66abc6b..bd57d8fb54f1 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -83,6 +83,9 @@ struct net { struct llist_node defer_free_list; struct llist_node cleanup_list; /* namespaces on death row */ + struct list_head ptype_all; + struct list_head ptype_specific; + #ifdef CONFIG_KEYS struct key_tag *key_domain; /* Key domain of operation tag */ #endif diff --git a/net/core/dev.c b/net/core/dev.c index 235560341765..bcf81c3ff6a3 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -572,10 +572,18 @@ static inline void netdev_set_addr_lockdep_class(struct net_device *dev) static inline struct list_head *ptype_head(const struct packet_type *pt) { - if (pt->type == htons(ETH_P_ALL)) - return pt->dev ? &pt->dev->ptype_all : &net_hotdata.ptype_all; - else - return pt->dev ? &pt->dev->ptype_specific : + if (pt->type == htons(ETH_P_ALL)) { + if (!pt->af_packet_net && !pt->dev) + return NULL; + + return pt->dev ? &pt->dev->ptype_all : + &pt->af_packet_net->ptype_all; + } + + if (pt->dev) + return &pt->dev->ptype_specific; + + return pt->af_packet_net ? &pt->af_packet_net->ptype_specific : &ptype_base[ntohs(pt->type) & PTYPE_HASH_MASK]; } @@ -596,6 +604,9 @@ void dev_add_pack(struct packet_type *pt) { struct list_head *head = ptype_head(pt); + if (WARN_ON_ONCE(!head)) + return; + spin_lock(&ptype_lock); list_add_rcu(&pt->list, head); spin_unlock(&ptype_lock); @@ -620,6 +631,9 @@ void __dev_remove_pack(struct packet_type *pt) struct list_head *head = ptype_head(pt); struct packet_type *pt1; + if (!head) + return; + spin_lock(&ptype_lock); list_for_each_entry(pt1, head, list) { @@ -2441,16 +2455,21 @@ static inline bool skb_loop_sk(struct packet_type *ptype, struct sk_buff *skb) } /** - * dev_nit_active - return true if any network interface taps are in use + * dev_nit_active_rcu - return true if any network interface taps are in use + * + * The caller must hold the RCU lock * * @dev: network device to check for the presence of taps */ -bool dev_nit_active(struct net_device *dev) +bool dev_nit_active_rcu(const struct net_device *dev) { - return !list_empty(&net_hotdata.ptype_all) || + /* Callers may hold either RCU or RCU BH lock */ + WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_bh_held()); + + return !list_empty(&dev_net(dev)->ptype_all) || !list_empty(&dev->ptype_all); } -EXPORT_SYMBOL_GPL(dev_nit_active); +EXPORT_SYMBOL_GPL(dev_nit_active_rcu); /* * Support routine. Sends outgoing frames to any network @@ -2459,11 +2478,12 @@ EXPORT_SYMBOL_GPL(dev_nit_active); void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev) { - struct list_head *ptype_list = &net_hotdata.ptype_all; struct packet_type *ptype, *pt_prev = NULL; + struct list_head *ptype_list; struct sk_buff *skb2 = NULL; rcu_read_lock(); + ptype_list = &dev_net_rcu(dev)->ptype_all; again: list_for_each_entry_rcu(ptype, ptype_list, list) { if (READ_ONCE(ptype->ignore_outgoing)) @@ -2507,7 +2527,7 @@ again: pt_prev = ptype; } - if (ptype_list == &net_hotdata.ptype_all) { + if (ptype_list != &dev->ptype_all) { ptype_list = &dev->ptype_all; goto again; } @@ -3752,7 +3772,7 @@ static int xmit_one(struct sk_buff *skb, struct net_device *dev, unsigned int len; int rc; - if (dev_nit_active(dev)) + if (dev_nit_active_rcu(dev)) dev_queue_xmit_nit(skb, dev); len = skb->len; @@ -5696,7 +5716,8 @@ another_round: if (pfmemalloc) goto skip_taps; - list_for_each_entry_rcu(ptype, &net_hotdata.ptype_all, list) { + list_for_each_entry_rcu(ptype, &dev_net_rcu(skb->dev)->ptype_all, + list) { if (pt_prev) ret = deliver_skb(skb, pt_prev, orig_dev); pt_prev = ptype; @@ -5808,6 +5829,14 @@ check_vlan_id: deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type, &ptype_base[ntohs(type) & PTYPE_HASH_MASK]); + + /* orig_dev and skb->dev could belong to different netns; + * Even in such case we need to traverse only the list + * coming from skb->dev, as the ptype owner (packet socket) + * will use dev_net(skb->dev) to do namespace filtering. + */ + deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type, + &dev_net_rcu(skb->dev)->ptype_specific); } deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type, diff --git a/net/core/hotdata.c b/net/core/hotdata.c index d0aaaaa556f2..0bc893d5f07b 100644 --- a/net/core/hotdata.c +++ b/net/core/hotdata.c @@ -7,7 +7,6 @@ struct net_hotdata net_hotdata __cacheline_aligned = { .offload_base = LIST_HEAD_INIT(net_hotdata.offload_base), - .ptype_all = LIST_HEAD_INIT(net_hotdata.ptype_all), .gro_normal_batch = 8, .netdev_budget = 300, diff --git a/net/core/net-procfs.c b/net/core/net-procfs.c index fa6d3969734a..3e92bf0f9060 100644 --- a/net/core/net-procfs.c +++ b/net/core/net-procfs.c @@ -185,7 +185,13 @@ static void *ptype_get_idx(struct seq_file *seq, loff_t pos) } } - list_for_each_entry_rcu(pt, &net_hotdata.ptype_all, list) { + list_for_each_entry_rcu(pt, &seq_file_net(seq)->ptype_all, list) { + if (i == pos) + return pt; + ++i; + } + + list_for_each_entry_rcu(pt, &seq_file_net(seq)->ptype_specific, list) { if (i == pos) return pt; ++i; @@ -210,6 +216,7 @@ static void *ptype_seq_start(struct seq_file *seq, loff_t *pos) static void *ptype_seq_next(struct seq_file *seq, void *v, loff_t *pos) { + struct net *net = seq_file_net(seq); struct net_device *dev; struct packet_type *pt; struct list_head *nxt; @@ -232,15 +239,22 @@ static void *ptype_seq_next(struct seq_file *seq, void *v, loff_t *pos) goto found; } } - - nxt = net_hotdata.ptype_all.next; - goto ptype_all; + nxt = net->ptype_all.next; + goto net_ptype_all; } - if (pt->type == htons(ETH_P_ALL)) { -ptype_all: - if (nxt != &net_hotdata.ptype_all) + if (pt->af_packet_net) { +net_ptype_all: + if (nxt != &net->ptype_all && nxt != &net->ptype_specific) goto found; + + if (nxt == &net->ptype_all) { + /* continue with ->ptype_specific if it's not empty */ + nxt = net->ptype_specific.next; + if (nxt != &net->ptype_specific) + goto found; + } + hash = 0; nxt = ptype_base[0].next; } else diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index 4303f2a49262..b0dfdf791ece 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -340,6 +340,8 @@ static __net_init void preinit_net(struct net *net, struct user_namespace *user_ lock_set_cmp_fn(&net->rtnl_mutex, rtnl_net_lock_cmp_fn, NULL); #endif + INIT_LIST_HEAD(&net->ptype_all); + INIT_LIST_HEAD(&net->ptype_specific); preinit_net_sysctl(net); } -- 2.25.1