[PATCH mptcp-next v3 08/14] mptcp: netlink: Add MPTCP_PM_CMD_REMOVE

[Kishen Maloor <kishen.maloor@intel.com>]

This change adds a MPTCP netlink command for issuing
REMOVE_ADDR signals for a specific address over the chosen MPTCP
connection from a userspace path manager.

The command requires the following parameters: {token, loc_id}.

Signed-off-by: Kishen Maloor <kishen.maloor@intel.com>
---
v3: update the per-msk count of local addresses populated by the
userspace PM; this is the value that needs to stay within the
new sysctl configurable limit
---
 include/uapi/linux/mptcp.h |  2 ++
 net/mptcp/pm_netlink.c     | 71 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 73 insertions(+)

diff --git a/include/uapi/linux/mptcp.h b/include/uapi/linux/mptcp.h
index 088bdfbf442c..c2d7d3cefd02 100644
--- a/include/uapi/linux/mptcp.h
+++ b/include/uapi/linux/mptcp.h
@@ -56,6 +56,7 @@ enum {
 	MPTCP_PM_ATTR_RCV_ADD_ADDRS,			/* u32 */
 	MPTCP_PM_ATTR_SUBFLOWS,				/* u32 */
 	MPTCP_PM_ATTR_TOKEN,				/* u32 */
+	MPTCP_PM_ATTR_LOC_ID,				/* u8 */
 
 	__MPTCP_PM_ATTR_MAX
 };
@@ -95,6 +96,7 @@ enum {
 	MPTCP_PM_CMD_GET_LIMITS,
 	MPTCP_PM_CMD_SET_FLAGS,
 	MPTCP_PM_CMD_ANNOUNCE,
+	MPTCP_PM_CMD_REMOVE,
 
 	__MPTCP_PM_CMD_AFTER_LAST
 };
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index e880177742d3..f2130374c5fc 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -1313,6 +1313,7 @@ static const struct nla_policy mptcp_pm_policy[MPTCP_PM_ATTR_MAX + 1] = {
 	[MPTCP_PM_ATTR_RCV_ADD_ADDRS]	= { .type	= NLA_U32,	},
 	[MPTCP_PM_ATTR_SUBFLOWS]	= { .type	= NLA_U32,	},
 	[MPTCP_PM_ATTR_TOKEN]		= { .type	= NLA_U32,	},
+	[MPTCP_PM_ATTR_LOC_ID]		= { .type	= NLA_U8,	},
 };
 
 void mptcp_pm_nl_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk)
@@ -1749,6 +1750,7 @@ static void mptcp_pm_remove_addrs_and_subflows(struct mptcp_sock *msk,
 		    slist.nr < MPTCP_RM_IDS_MAX) {
 			alist.ids[alist.nr++] = entry->addr.id;
 			slist.ids[slist.nr++] = entry->addr.id;
+			remove_anno_list_by_saddr(msk, &entry->addr);
 		} else if (remove_anno_list_by_saddr(msk, &entry->addr) &&
 			 alist.nr < MPTCP_RM_IDS_MAX) {
 			alist.ids[alist.nr++] = entry->addr.id;
@@ -2375,6 +2377,70 @@ void mptcp_event_addr_removed(const struct mptcp_sock *msk, uint8_t id)
 	kfree_skb(skb);
 }
 
+static int mptcp_nl_cmd_remove(struct sk_buff *skb, struct genl_info *info)
+{
+	struct nlattr *token = info->attrs[MPTCP_PM_ATTR_TOKEN];
+	struct nlattr *id = info->attrs[MPTCP_PM_ATTR_LOC_ID];
+	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
+	struct mptcp_pm_addr_entry *match = NULL;
+	struct mptcp_pm_addr_entry *entry;
+	struct mptcp_sock *msk;
+	LIST_HEAD(free_list);
+	u32 token_val;
+	u8 id_val;
+
+	if (!id || !token) {
+		GENL_SET_ERR_MSG(info, "missing required inputs");
+		return -EINVAL;
+	}
+
+	id_val = nla_get_u8(id);
+	token_val = nla_get_u32(token);
+
+	msk = mptcp_token_get_sock(sock_net(skb->sk), token_val);
+	if (!msk) {
+		NL_SET_ERR_MSG_ATTR(info->extack, token, "invalid token");
+		return -EINVAL;
+	}
+
+	if (READ_ONCE(msk->pm.pm_type) != MPTCP_PM_TYPE_USERSPACE) {
+		GENL_SET_ERR_MSG(info, "invalid request; userspace PM not selected");
+		return -EINVAL;
+	}
+
+	lock_sock((struct sock *)msk);
+
+	list_for_each_entry(entry, &msk->local_addr_list, list) {
+		if (entry->addr.id == id_val) {
+			match = entry;
+			break;
+		}
+	}
+
+	if (!match) {
+		GENL_SET_ERR_MSG(info, "address with specified id not found");
+		release_sock((struct sock *)msk);
+		return -EINVAL;
+	}
+
+	list_move(&match->list, &free_list);
+
+	mptcp_pm_remove_addrs_and_subflows(msk, &free_list);
+
+	release_sock((struct sock *)msk);
+
+	spin_lock_bh(&msk->pm.lock);
+	--msk->pm.local_addr_used;
+	spin_unlock_bh(&msk->pm.lock);
+
+	list_for_each_entry_safe(match, entry, &free_list, list) {
+		if (match->lsk_ref)
+			lsk_list_release(pernet, match->lsk_ref);
+		kfree(match);
+	}
+	return 0;
+}
+
 void mptcp_event_addr_announced(const struct mptcp_sock *msk,
 				const struct mptcp_addr_info *info,
 				const struct sock *ssk)
@@ -2526,6 +2592,11 @@ static const struct genl_small_ops mptcp_pm_ops[] = {
 		.doit   = mptcp_nl_cmd_announce,
 		.flags  = GENL_ADMIN_PERM,
 	},
+	{
+		.cmd    = MPTCP_PM_CMD_REMOVE,
+		.doit   = mptcp_nl_cmd_remove,
+		.flags  = GENL_ADMIN_PERM,
+	},
 };
 
 static struct genl_family mptcp_genl_family __ro_after_init = {
-- 
2.31.1