p4tc: Introduce subscription filters for table entries

Introduce subscription filters, as of now only for table entries, but we
intend to include externs in the future. To subscribe to a specific
event with a filter, the user must specify it when running tc monitor.

For example, if the user wants to filter the table entry create commands
from a pipeline (ptables), a table (tname2) with entry key srcport ==
80, the user will issue the following command:

tc monitor command/create ptables/table/cb/tname2 \
filter key.ptables.cb.tname2.srcPort = 80

If one creates a table entry like the following:

tc p4 create ptables/table/cb/tname2 srcPort  80 dstPort  443

And they would see the following in tc monitor:

created pipeline:  ptables(id 22)
 table: cb/tname2(id 2)entry priority 64000[permissions -RUD-PS-R--X--]
    entry key
     srcPort id:1 size:16b type:bit16 exact fieldval  80
     dstPort id:2 size:16b type:bit16 exact fieldval  443
    created by entity: tc (id 2)
    create by pid: 448
    created by process: tc
    dynamic false

    tmpl created false

Co-developed-by: Victor Nogueira <[email protected]>
Signed-off-by: Victor Nogueira <[email protected]>
Co-developed-by: Pedro Tammela <[email protected]>
Signed-off-by: Pedro Tammela <[email protected]>
Signed-off-by: Jamal Hadi Salim <[email protected]>

include/net/p4tc.h

@@ -69,6 +69,17 @@ struct p4tc_dump_ctx {
 	struct p4tc_filter *entry_filter;
 };
 
+struct p4tc_filter_data {
+	union {
+		struct {
+			u32 id;
+			struct p4tc_table_entry *entry;
+		} table;
+	};
+	int cmd;
+	u32 obj_id;
+};
+
 enum {
 	P4TC_FILTER_OBJ_UNSPEC,
 	P4TC_FILTER_OBJ_TMPL_PIPELINE,
@@ -82,6 +93,39 @@ enum {
 
 #define P4TC_FILTER_OBJ_MAX (__P4TC_FILTER_OBJ_MAX - 1)
 
+int
+p4tc_nlmsg_filtered_notify(struct net *net, struct sk_buff *skb,
+			   const u32 portid, gfp_t gfp_flags,
+			   const bool echo, netlink_filter_fn filter,
+			   void *filter_data);
+
+static inline int p4tc_obj_to_filter_obj(const u32 p4tc_obj, bool runtime)
+{
+	if (runtime) {
+		switch (p4tc_obj) {
+		case P4TC_OBJ_RUNTIME_TABLE:
+			return P4TC_FILTER_OBJ_RUNTIME_TABLE;
+		case P4TC_OBJ_RUNTIME_EXTERN:
+			return P4TC_FILTER_OBJ_RUNTIME_EXT;
+		default:
+			return -EINVAL;
+		}
+	} else {
+		switch (p4tc_obj) {
+		case P4TC_OBJ_PIPELINE:
+			return P4TC_FILTER_OBJ_TMPL_PIPELINE;
+		case P4TC_OBJ_ACT:
+			return P4TC_FILTER_OBJ_TMPL_ACT;
+		case P4TC_OBJ_TABLE:
+			return P4TC_FILTER_OBJ_TMPL_TABLE;
+		case P4TC_OBJ_EXT:
+			return P4TC_FILTER_OBJ_TMPL_EXT;
+		default:
+			return -EINVAL;
+		}
+	}
+}
+
 struct p4tc_template_common;
 
 struct p4tc_path_nlattrs {
@@ -742,8 +786,12 @@ p4tc_tmpl_table_entry_cu(struct net *net, struct nlattr *arg,
 			 struct p4tc_table *table,
 			 struct netlink_ext_ack *extack);
 int p4tc_tbl_entry_root(struct net *net, struct sk_buff *skb,
-			struct nlmsghdr *n, int cmd,
+			struct nlmsghdr *n, struct nlattr **tb,
 			struct netlink_ext_ack *extack);
+int p4tc_tbl_entry_filter_sub(struct sk_buff *skb,
+			      struct p4tc_path_nlattrs *nl_path_attrs,
+			      struct nlattr *nla, u32 cmd,
+			      struct netlink_ext_ack *extack);
 int p4tc_tbl_entry_dumpit(struct net *net, struct sk_buff *skb,
 			  struct netlink_callback *cb,
 			  struct nlattr *arg, char *p_name);
@@ -759,7 +807,14 @@ p4tc_filter_build(struct p4tc_filter_context *ctx,
 		  struct nlattr *nla, struct netlink_ext_ack *extack);
 bool p4tc_filter_exec(struct p4tc_filter *filter,
 		      struct p4tc_table_entry *entry);
+int p4tc_filter_broadcast_cb(struct sock *dsk, struct sk_buff *skb,
+			     void *data);
 void p4tc_filter_destroy(struct p4tc_filter *filter);
+void p4tc_filter_sock_table_init(void);
+int p4tc_filter_subscribe(struct sk_buff *skb,
+			  struct p4tc_filter_context *ctx,
+			  struct nlattr *nla,
+			  struct netlink_ext_ack *extack);
 
 struct tcf_p4act *
 p4a_runt_prealloc_get_next(struct p4tc_act *act);

include/net/p4tc_ext_api.h

@@ -115,7 +115,7 @@ int p4tc_ctl_extern_dump(struct sk_buff *skb, struct netlink_callback *cb,
 void p4tc_ext_purge(struct idr *idr);
 void p4tc_ext_inst_purge(struct p4tc_extern_inst *inst);
 
-int p4tc_ctl_extern(struct sk_buff *skb, struct nlmsghdr *n, int cmd,
+int p4tc_ctl_extern(struct sk_buff *skb, struct nlmsghdr *n, struct nlattr **tb,
 		    struct netlink_ext_ack *extack);
 struct p4tc_extern_param *
 p4tc_ext_param_find_byanyattr(struct idr *params_idr,

include/uapi/linux/p4tc.h

@@ -100,13 +100,24 @@ enum {
 #define p4tc_data_perm_rm_create(perm) \
 	(((perm) & ~P4TC_DATA_PERM_C))
 
+/* Root attributes */
+enum {
+	P4TC_SUBSCRIBE_UNSPEC,
+	P4TC_SUBSCRIBE_OBJNAME, /* object name */
+	P4TC_SUBSCRIBE_OBJID, /* object 32-bit ID */
+	__P4TC_SUBSCRIBE_MAX,
+};
+
+#define P4TC_SUBSCRIBE_MAX (__P4TC_SUBSCRIBE_MAX - 1)
+
 /* Root attributes */
 enum {
 	P4TC_ROOT_UNSPEC,
 	P4TC_ROOT, /* nested messages */
 	P4TC_ROOT_PNAME, /* string - mandatory for pipeline create */
 	P4TC_ROOT_COUNT,
 	P4TC_ROOT_FLAGS,
+	P4TC_ROOT_SUBSCRIBE, /* nested subscribe message, will contain filter */
 	__P4TC_ROOT_MAX,
 };
 
@@ -141,6 +152,7 @@ enum {
 	P4TC_PATH,
 	P4TC_PARAMS,
 	P4TC_COUNT,
+	P4TC_CMD,
 	__P4TC_MAX,
 };
 

include/uapi/linux/rtnetlink.h

@@ -792,6 +792,8 @@ enum rtnetlink_groups {
 #define RTNLGRP_TUNNEL		RTNLGRP_TUNNEL
 	RTNLGRP_STATS,
 #define RTNLGRP_STATS		RTNLGRP_STATS
+	RTNLGRP_P4TC,
+#define RTNLGRP_P4TC		RTNLGRP_P4TC
 	__RTNLGRP_MAX
 };
 #define RTNLGRP_MAX	(__RTNLGRP_MAX - 1)

net/sched/p4tc/p4tc_ext.c

@@ -1984,28 +1984,22 @@ int p4tc_ctl_extern_dump(struct sk_buff *skb, struct netlink_callback *cb,
 	return skb->len;
 }
 
-int p4tc_ctl_extern(struct sk_buff *skb, struct nlmsghdr *n, int cmd,
+int p4tc_ctl_extern(struct sk_buff *skb, struct nlmsghdr *n, struct nlattr **tb,
 		    struct netlink_ext_ack *extack)
 {
-	struct nlattr *tb[P4TC_ROOT_MAX + 1];
 	struct net *net = sock_net(skb->sk);
 	u32 portid = NETLINK_CB(skb).portid;
 	struct p4tc_pipeline *pipeline;
 	struct nlattr *root;
 	char *pname = NULL;
 	u32 flags = 0;
-	int ret = 0;
 
-	if (cmd != RTM_P4TC_GET && !netlink_capable(skb, CAP_NET_ADMIN)) {
+	if (n->nlmsg_type != RTM_P4TC_GET &&
+	    !netlink_capable(skb, CAP_NET_ADMIN)) {
 		NL_SET_ERR_MSG(extack, "Need CAP_NET_ADMIN to do CUD ops");
 		return -EPERM;
 	}
 
-	ret = nlmsg_parse(n, sizeof(struct p4tcmsg), tb, P4TC_ROOT_MAX,
-			  p4tc_root_policy, extack);
-	if (ret < 0)
-		return ret;
-
 	if (tb[P4TC_ROOT_PNAME])
 		pname = nla_data(tb[P4TC_ROOT_PNAME]);