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Re: [tipc-discussion] [net-next v2] tipc: add loopback device tracking
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From: Jon M. <jon...@er...> - 2019-06-20 12:10:48
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Acked-by: Jon Maloy jon...@er...
> -----Original Message-----
> From: John Rutherford <joh...@de...>
> Sent: 18-Jun-19 20:11
> To: tip...@li...
> Subject: [tipc-discussion] [net-next v2] tipc: add loopback device tracking
>
> Since node internal messages are passed directly to socket it is not possible to
> observe this message exchange via tcpdump or wireshark.
>
> We now remedy this by making it possible to clone such messages and send
> the clones to the loopback interface. The clones are dropped at reception and
> have no functional role except making the traffic visible.
>
> The feature is turned on/off by enabling/disabling the loopback "bearer"
> "eth:lo".
>
> Signed-off-by: John Rutherford <joh...@de...>
> ---
> net/tipc/bcast.c | 4 +++-
> net/tipc/bearer.c | 67
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> net/tipc/bearer.h | 3 +++
> net/tipc/core.c | 5 ++++-
> net/tipc/core.h | 12 ++++++++++
> net/tipc/node.c | 1 +
> net/tipc/topsrv.c | 2 ++
> 7 files changed, 92 insertions(+), 2 deletions(-)
>
> diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c index 6c997d4..235331d
> 100644
> --- a/net/tipc/bcast.c
> +++ b/net/tipc/bcast.c
> @@ -406,8 +406,10 @@ int tipc_mcast_xmit(struct net *net, struct
> sk_buff_head *pkts,
> rc = tipc_bcast_xmit(net, pkts, cong_link_cnt);
> }
>
> - if (dests->local)
> + if (dests->local) {
> + tipc_loopback_trace(net, &localq);
> tipc_sk_mcast_rcv(net, &localq, &inputq);
> + }
> exit:
> /* This queue should normally be empty by now */
> __skb_queue_purge(pkts);
> diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c index 2bed658..27b4fd7
> 100644
> --- a/net/tipc/bearer.c
> +++ b/net/tipc/bearer.c
> @@ -836,6 +836,12 @@ int __tipc_nl_bearer_disable(struct sk_buff *skb,
> struct genl_info *info)
>
> name = nla_data(attrs[TIPC_NLA_BEARER_NAME]);
>
> + if (!strcmp(name, "eth:lo")) {
> + tipc_net(net)->loopback_trace = false;
> + pr_info("Disabled packet tracing on loopback interface\n");
> + return 0;
> + }
> +
> bearer = tipc_bearer_find(net, name);
> if (!bearer)
> return -EINVAL;
> @@ -881,6 +887,12 @@ int __tipc_nl_bearer_enable(struct sk_buff *skb,
> struct genl_info *info)
>
> bearer = nla_data(attrs[TIPC_NLA_BEARER_NAME]);
>
> + if (!strcmp(bearer, "eth:lo")) {
> + tipc_net(net)->loopback_trace = true;
> + pr_info("Enabled packet tracing on loopback interface\n");
> + return 0;
> + }
> +
> if (attrs[TIPC_NLA_BEARER_DOMAIN])
> domain = nla_get_u32(attrs[TIPC_NLA_BEARER_DOMAIN]);
>
> @@ -1021,6 +1033,61 @@ int tipc_nl_bearer_set(struct sk_buff *skb, struct
> genl_info *info)
> return err;
> }
>
> +void tipc_clone_to_loopback(struct net *net, struct sk_buff_head
> +*xmitq) {
> + struct net_device *dev = net->loopback_dev;
> + struct sk_buff *skb, *_skb;
> + int exp;
> +
> + skb_queue_walk(xmitq, _skb) {
> + skb = pskb_copy(_skb, GFP_ATOMIC);
> + if (!skb)
> + continue;
> + exp = SKB_DATA_ALIGN(dev->hard_header_len -
> skb_headroom(skb));
> + if (exp > 0 && pskb_expand_head(skb, exp, 0, GFP_ATOMIC)) {
> + kfree_skb(skb);
> + continue;
> + }
> + skb_reset_network_header(skb);
> + skb->dev = dev;
> + skb->protocol = htons(ETH_P_TIPC);
> + dev_hard_header(skb, dev, ETH_P_TIPC, dev->dev_addr,
> + dev->dev_addr, skb->len);
> + dev_queue_xmit(skb);
> + }
> +}
> +
> +static int tipc_loopback_rcv_pkt(struct sk_buff *skb, struct net_device *dev,
> + struct packet_type *pt, struct net_device *od) {
> + consume_skb(skb);
> + return NET_RX_SUCCESS;
> +}
> +
> +int tipc_attach_loopback(struct net *net) {
> + struct net_device *dev = net->loopback_dev;
> + struct tipc_net *tn = tipc_net(net);
> +
> + if (!dev)
> + return -ENODEV;
> + dev_hold(dev);
> + tn->loopback_pt.dev = dev;
> + tn->loopback_pt.type = htons(ETH_P_TIPC);
> + tn->loopback_pt.func = tipc_loopback_rcv_pkt;
> + tn->loopback_trace = false;
> + dev_add_pack(&tn->loopback_pt);
> + return 0;
> +}
> +
> +void tipc_detach_loopback(struct net *net) {
> + struct tipc_net *tn = tipc_net(net);
> +
> + dev_remove_pack(&tn->loopback_pt);
> + dev_put(net->loopback_dev);
> +}
> +
> static int __tipc_nl_add_media(struct tipc_nl_msg *msg,
> struct tipc_media *media, int nlflags) { diff --git
> a/net/tipc/bearer.h b/net/tipc/bearer.h index 7f4c569..ef7fad9 100644
> --- a/net/tipc/bearer.h
> +++ b/net/tipc/bearer.h
> @@ -232,6 +232,9 @@ void tipc_bearer_xmit(struct net *net, u32
> bearer_id,
> struct tipc_media_addr *dst);
> void tipc_bearer_bc_xmit(struct net *net, u32 bearer_id,
> struct sk_buff_head *xmitq);
> +void tipc_clone_to_loopback(struct net *net, struct sk_buff_head
> +*xmitq); int tipc_attach_loopback(struct net *net); void
> +tipc_detach_loopback(struct net *net);
>
> /* check if device MTU is too low for tipc headers */ static inline bool
> tipc_mtu_bad(struct net_device *dev, unsigned int reserve) diff --git
> a/net/tipc/core.c b/net/tipc/core.c index ed536c0..1867687 100644
> --- a/net/tipc/core.c
> +++ b/net/tipc/core.c
> @@ -81,7 +81,9 @@ static int __net_init tipc_init_net(struct net *net)
> err = tipc_bcast_init(net);
> if (err)
> goto out_bclink;
> -
> + err = tipc_attach_loopback(net);
> + if (err)
> + goto out_bclink;
> return 0;
>
> out_bclink:
> @@ -94,6 +96,7 @@ static int __net_init tipc_init_net(struct net *net)
>
> static void __net_exit tipc_exit_net(struct net *net) {
> + tipc_detach_loopback(net);
> tipc_net_stop(net);
> tipc_bcast_stop(net);
> tipc_nametbl_stop(net);
> diff --git a/net/tipc/core.h b/net/tipc/core.h index 7a68e1b..c1c2906 100644
> --- a/net/tipc/core.h
> +++ b/net/tipc/core.h
> @@ -67,6 +67,7 @@ struct tipc_link;
> struct tipc_name_table;
> struct tipc_topsrv;
> struct tipc_monitor;
> +void tipc_clone_to_loopback(struct net *net, struct sk_buff_head
> +*pkts);
>
> #define TIPC_MOD_VER "2.0.0"
>
> @@ -125,6 +126,10 @@ struct tipc_net {
>
> /* Cluster capabilities */
> u16 capabilities;
> +
> + /* Tracing of node internal messages */
> + struct packet_type loopback_pt;
> + bool loopback_trace;
> };
>
> static inline struct tipc_net *tipc_net(struct net *net) @@ -152,6 +157,13
> @@ static inline struct tipc_topsrv *tipc_topsrv(struct net *net)
> return tipc_net(net)->topsrv;
> }
>
> +static inline void tipc_loopback_trace(struct net *net,
> + struct sk_buff_head *pkts)
> +{
> + if (unlikely(tipc_net(net)->loopback_trace))
> + tipc_clone_to_loopback(net, pkts);
> +}
> +
> static inline unsigned int tipc_hashfn(u32 addr) {
> return addr & (NODE_HTABLE_SIZE - 1);
> diff --git a/net/tipc/node.c b/net/tipc/node.c index 9e106d3..7e58831
> 100644
> --- a/net/tipc/node.c
> +++ b/net/tipc/node.c
> @@ -1439,6 +1439,7 @@ int tipc_node_xmit(struct net *net, struct
> sk_buff_head *list,
> int rc;
>
> if (in_own_node(net, dnode)) {
> + tipc_loopback_trace(net, list);
> tipc_sk_rcv(net, list);
> return 0;
> }
> diff --git a/net/tipc/topsrv.c b/net/tipc/topsrv.c index f345662..e3a6ba1
> 100644
> --- a/net/tipc/topsrv.c
> +++ b/net/tipc/topsrv.c
> @@ -40,6 +40,7 @@
> #include "socket.h"
> #include "addr.h"
> #include "msg.h"
> +#include "bearer.h"
> #include <net/sock.h>
> #include <linux/module.h>
>
> @@ -608,6 +609,7 @@ static void tipc_topsrv_kern_evt(struct net *net,
> struct tipc_event *evt)
> memcpy(msg_data(buf_msg(skb)), evt, sizeof(*evt));
> skb_queue_head_init(&evtq);
> __skb_queue_tail(&evtq, skb);
> + tipc_loopback_trace(net, &evtq);
> tipc_sk_rcv(net, &evtq);
> }
>
> --
> 2.11.0
>
>
>
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