psp: report basic stats from the core

Track and report stats common to all psp devices from the core. A
'stale-event' is when the core marks the rx state of an active
psp_assoc as incapable of authenticating psp encapsulated data.

Signed-off-by: Daniel Zahka <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

Documentation/netlink/specs/psp.yaml

···
         name: spi
         doc: Security Parameters Index (SPI) of the association.
         type: u32
+  -
+    name: stats
+    attributes:
+      -
+        name: dev-id
+        doc: PSP device ID.
+        type: u32
+        checks:
+          min: 1
+      -
+        name: key-rotations
+        type: uint
+        doc: |
+          Number of key rotations during the lifetime of the device.
+          Kernel statistic.
+      -
+        name: stale-events
+        type: uint
+        doc: |
+          Number of times a socket's Rx got shut down due to using
+          a key which went stale (fully rotated out).
+          Kernel statistic.
 
 operations:
   list:
···
           attributes: []
         pre: psp-assoc-device-get-locked
         post: psp-device-unlock
+
+    -
+      name: get-stats
+      doc: Get device statistics.
+      attribute-set: stats
+      do:
+        request:
+          attributes:
+            - dev-id
+        reply: &stats-all
+          attributes:
+            - dev-id
+            - key-rotations
+            - stale-events
+        pre: psp-device-get-locked
+        post: psp-device-unlock
+      dump:
+        reply: *stats-all
 
 mcast-groups:
   list:

include/net/psp/types.h

···
  *			device key
  * @stale_assocs:	associations which use a rotated out key
  *
+ * @stats:	statistics maintained by the core
+ * @stats.rotations:	See stats attr key-rotations
+ * @stats.stales:	See stats attr stale-events
+ *
  * @rcu:	RCU head for freeing the structure
  */
 struct psp_dev {
···
 	struct list_head active_assocs;
 	struct list_head prev_assocs;
 	struct list_head stale_assocs;
+
+	struct {
+		unsigned long rotations;
+		unsigned long stales;
+	} stats;
 
 	struct rcu_head rcu;
 };

include/uapi/linux/psp.h

···
 };
 
 enum {
+	PSP_A_STATS_DEV_ID = 1,
+	PSP_A_STATS_KEY_ROTATIONS,
+	PSP_A_STATS_STALE_EVENTS,
+
+	__PSP_A_STATS_MAX,
+	PSP_A_STATS_MAX = (__PSP_A_STATS_MAX - 1)
+};
+
+enum {
 	PSP_CMD_DEV_GET = 1,
 	PSP_CMD_DEV_ADD_NTF,
 	PSP_CMD_DEV_DEL_NTF,
···
 	PSP_CMD_KEY_ROTATE_NTF,
 	PSP_CMD_RX_ASSOC,
 	PSP_CMD_TX_ASSOC,
+	PSP_CMD_GET_STATS,
 
 	__PSP_CMD_MAX,
 	PSP_CMD_MAX = (__PSP_CMD_MAX - 1)

net/psp/psp-nl-gen.c

···
 	[PSP_A_ASSOC_SOCK_FD] = { .type = NLA_U32, },
 };
 
+/* PSP_CMD_GET_STATS - do */
+static const struct nla_policy psp_get_stats_nl_policy[PSP_A_STATS_DEV_ID + 1] = {
+	[PSP_A_STATS_DEV_ID] = NLA_POLICY_MIN(NLA_U32, 1),
+};
+
 /* Ops table for psp */
 static const struct genl_split_ops psp_nl_ops[] = {
 	{
···
 		.policy		= psp_tx_assoc_nl_policy,
 		.maxattr	= PSP_A_ASSOC_SOCK_FD,
 		.flags		= GENL_CMD_CAP_DO,
+	},
+	{
+		.cmd		= PSP_CMD_GET_STATS,
+		.pre_doit	= psp_device_get_locked,
+		.doit		= psp_nl_get_stats_doit,
+		.post_doit	= psp_device_unlock,
+		.policy		= psp_get_stats_nl_policy,
+		.maxattr	= PSP_A_STATS_DEV_ID,
+		.flags		= GENL_CMD_CAP_DO,
+	},
+	{
+		.cmd	= PSP_CMD_GET_STATS,
+		.dumpit	= psp_nl_get_stats_dumpit,
+		.flags	= GENL_CMD_CAP_DUMP,
 	},
 };
 

net/psp/psp-nl-gen.h

···
 int psp_nl_key_rotate_doit(struct sk_buff *skb, struct genl_info *info);
 int psp_nl_rx_assoc_doit(struct sk_buff *skb, struct genl_info *info);
 int psp_nl_tx_assoc_doit(struct sk_buff *skb, struct genl_info *info);
+int psp_nl_get_stats_doit(struct sk_buff *skb, struct genl_info *info);
+int psp_nl_get_stats_dumpit(struct sk_buff *skb, struct netlink_callback *cb);
 
 enum {
 	PSP_NLGRP_MGMT,

net/psp/psp_nl.c

···
 		     psd->generation & ~PSP_GEN_VALID_MASK);
 
 	psp_assocs_key_rotated(psd);
+	psd->stats.rotations++;
 
 	nlmsg_end(ntf, (struct nlmsghdr *)ntf->data);
 	genlmsg_multicast_netns(&psp_nl_family, dev_net(psd->main_netdev), ntf,
···
 
 err_free_msg:
 	nlmsg_free(rsp);
+	return err;
+}
+
+static int
+psp_nl_stats_fill(struct psp_dev *psd, struct sk_buff *rsp,
+		  const struct genl_info *info)
+{
+	void *hdr;
+
+	hdr = genlmsg_iput(rsp, info);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	if (nla_put_u32(rsp, PSP_A_STATS_DEV_ID, psd->id) ||
+	    nla_put_uint(rsp, PSP_A_STATS_KEY_ROTATIONS,
+			 psd->stats.rotations) ||
+	    nla_put_uint(rsp, PSP_A_STATS_STALE_EVENTS, psd->stats.stales))
+		goto err_cancel_msg;
+
+	genlmsg_end(rsp, hdr);
+	return 0;
+
+err_cancel_msg:
+	genlmsg_cancel(rsp, hdr);
+	return -EMSGSIZE;
+}
+
+int psp_nl_get_stats_doit(struct sk_buff *skb, struct genl_info *info)
+{
+	struct psp_dev *psd = info->user_ptr[0];
+	struct sk_buff *rsp;
+	int err;
+
+	rsp = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!rsp)
+		return -ENOMEM;
+
+	err = psp_nl_stats_fill(psd, rsp, info);
+	if (err)
+		goto err_free_msg;
+
+	return genlmsg_reply(rsp, info);
+
+err_free_msg:
+	nlmsg_free(rsp);
+	return err;
+}
+
+static int
+psp_nl_stats_get_dumpit_one(struct sk_buff *rsp, struct netlink_callback *cb,
+			    struct psp_dev *psd)
+{
+	if (psp_dev_check_access(psd, sock_net(rsp->sk)))
+		return 0;
+
+	return psp_nl_stats_fill(psd, rsp, genl_info_dump(cb));
+}
+
+int psp_nl_get_stats_dumpit(struct sk_buff *rsp, struct netlink_callback *cb)
+{
+	struct psp_dev *psd;
+	int err = 0;
+
+	mutex_lock(&psp_devs_lock);
+	xa_for_each_start(&psp_devs, cb->args[0], psd, cb->args[0]) {
+		mutex_lock(&psd->lock);
+		err = psp_nl_stats_get_dumpit_one(rsp, cb, psd);
+		mutex_unlock(&psd->lock);
+		if (err)
+			break;
+	}
+	mutex_unlock(&psp_devs_lock);
+
 	return err;
 }

net/psp/psp_sock.c

···
 	/* Mark the stale associations as invalid, they will no longer
 	 * be able to Rx any traffic.
 	 */
-	list_for_each_entry_safe(pas, next, &psd->prev_assocs, assocs_list)
+	list_for_each_entry_safe(pas, next, &psd->prev_assocs, assocs_list) {
 		pas->generation |= ~PSP_GEN_VALID_MASK;
+		psd->stats.stales++;
+	}
 	list_splice_init(&psd->prev_assocs, &psd->stale_assocs);
 	list_splice_init(&psd->active_assocs, &psd->prev_assocs);