From 9eb8eff0cf2f1e1afc0756bb30cb9746ba90dd07 Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Sun, 10 May 2020 19:37:40 +0300 Subject: [PATCH] net: bridge: allow enslaving some DSA master network devices Commit 8db0a2ee2c63 ("net: bridge: reject DSA-enabled master netdevices as bridge members") added a special check in br_if.c in order to check for a DSA master network device with a tagging protocol configured. This was done because back then, such devices, once enslaved in a bridge would become inoperative and would not pass DSA tagged traffic anymore due to br_handle_frame returning RX_HANDLER_CONSUMED. But right now we have valid use cases which do require bridging of DSA masters. One such example is when the DSA master ports are DSA switch ports themselves (in a disjoint tree setup). This should be completely equivalent, functionally speaking, from having multiple DSA switches hanging off of the ports of a switchdev driver. So we should allow the enslaving of DSA tagged master network devices. Instead of the regular br_handle_frame(), install a new function br_handle_frame_dummy() on these DSA masters, which returns RX_HANDLER_PASS in order to call into the DSA specific tagging protocol handlers, and lift the restriction from br_add_if. Suggested-by: Nikolay Aleksandrov Suggested-by: Florian Fainelli Signed-off-by: Vladimir Oltean Acked-by: Nikolay Aleksandrov Reviewed-by: Florian Fainelli Tested-by: Florian Fainelli Signed-off-by: Jakub Kicinski --- include/net/dsa.h | 2 +- net/bridge/br_if.c | 32 +++++++++++++++++++++++--------- net/bridge/br_input.c | 23 ++++++++++++++++++++++- net/bridge/br_private.h | 6 +++--- 4 files changed, 49 insertions(+), 14 deletions(-) diff --git a/include/net/dsa.h b/include/net/dsa.h index 6dfc8c2f68b8..02fb5025e0ac 100644 --- a/include/net/dsa.h +++ b/include/net/dsa.h @@ -651,7 +651,7 @@ struct dsa_switch_driver { struct net_device *dsa_dev_to_net_device(struct device *dev); /* Keep inline for faster access in hot path */ -static inline bool netdev_uses_dsa(struct net_device *dev) +static inline bool netdev_uses_dsa(const struct net_device *dev) { #if IS_ENABLED(CONFIG_NET_DSA) return dev->dsa_ptr && dev->dsa_ptr->rcv; diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c index ca685c0cdf95..a0e9a7937412 100644 --- a/net/bridge/br_if.c +++ b/net/bridge/br_if.c @@ -563,18 +563,32 @@ int br_add_if(struct net_bridge *br, struct net_device *dev, unsigned br_hr, dev_hr; bool changed_addr; - /* Don't allow bridging non-ethernet like devices, or DSA-enabled - * master network devices since the bridge layer rx_handler prevents - * the DSA fake ethertype handler to be invoked, so we do not strip off - * the DSA switch tag protocol header and the bridge layer just return - * RX_HANDLER_CONSUMED, stopping RX processing for these frames. - */ + /* Don't allow bridging non-ethernet like devices. */ if ((dev->flags & IFF_LOOPBACK) || dev->type != ARPHRD_ETHER || dev->addr_len != ETH_ALEN || - !is_valid_ether_addr(dev->dev_addr) || - netdev_uses_dsa(dev)) + !is_valid_ether_addr(dev->dev_addr)) return -EINVAL; + /* Also don't allow bridging of net devices that are DSA masters, since + * the bridge layer rx_handler prevents the DSA fake ethertype handler + * to be invoked, so we don't get the chance to strip off and parse the + * DSA switch tag protocol header (the bridge layer just returns + * RX_HANDLER_CONSUMED, stopping RX processing for these frames). + * The only case where that would not be an issue is when bridging can + * already be offloaded, such as when the DSA master is itself a DSA + * or plain switchdev port, and is bridged only with other ports from + * the same hardware device. + */ + if (netdev_uses_dsa(dev)) { + list_for_each_entry(p, &br->port_list, list) { + if (!netdev_port_same_parent_id(dev, p->dev)) { + NL_SET_ERR_MSG(extack, + "Cannot do software bridging with a DSA master"); + return -EINVAL; + } + } + } + /* No bridging of bridges */ if (dev->netdev_ops->ndo_start_xmit == br_dev_xmit) { NL_SET_ERR_MSG(extack, @@ -618,7 +632,7 @@ int br_add_if(struct net_bridge *br, struct net_device *dev, if (err) goto err3; - err = netdev_rx_handler_register(dev, br_handle_frame, p); + err = netdev_rx_handler_register(dev, br_get_rx_handler(dev), p); if (err) goto err4; diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c index d5c34f36f0f4..59a318b9f646 100644 --- a/net/bridge/br_input.c +++ b/net/bridge/br_input.c @@ -17,6 +17,7 @@ #endif #include #include +#include #include #include #include "br_private.h" @@ -257,7 +258,7 @@ static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb) * Return NULL if skb is handled * note: already called with rcu_read_lock */ -rx_handler_result_t br_handle_frame(struct sk_buff **pskb) +static rx_handler_result_t br_handle_frame(struct sk_buff **pskb) { struct net_bridge_port *p; struct sk_buff *skb = *pskb; @@ -359,3 +360,23 @@ rx_handler_result_t br_handle_frame(struct sk_buff **pskb) } return RX_HANDLER_CONSUMED; } + +/* This function has no purpose other than to appease the br_port_get_rcu/rtnl + * helpers which identify bridged ports according to the rx_handler installed + * on them (so there _needs_ to be a bridge rx_handler even if we don't need it + * to do anything useful). This bridge won't support traffic to/from the stack, + * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal + * frames from the ETH_P_XDSA packet_type handler. + */ +static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb) +{ + return RX_HANDLER_PASS; +} + +rx_handler_func_t *br_get_rx_handler(const struct net_device *dev) +{ + if (netdev_uses_dsa(dev)) + return br_handle_frame_dummy; + + return br_handle_frame; +} diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h index 4dc21e8f7e33..7501be4eeba0 100644 --- a/net/bridge/br_private.h +++ b/net/bridge/br_private.h @@ -702,16 +702,16 @@ int nbp_backup_change(struct net_bridge_port *p, struct net_device *backup_dev); /* br_input.c */ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb); -rx_handler_result_t br_handle_frame(struct sk_buff **pskb); +rx_handler_func_t *br_get_rx_handler(const struct net_device *dev); static inline bool br_rx_handler_check_rcu(const struct net_device *dev) { - return rcu_dereference(dev->rx_handler) == br_handle_frame; + return rcu_dereference(dev->rx_handler) == br_get_rx_handler(dev); } static inline bool br_rx_handler_check_rtnl(const struct net_device *dev) { - return rcu_dereference_rtnl(dev->rx_handler) == br_handle_frame; + return rcu_dereference_rtnl(dev->rx_handler) == br_get_rx_handler(dev); } static inline struct net_bridge_port *br_port_get_check_rcu(const struct net_device *dev) -- GitLab