cfg80211/nl80211: Add PMKSA caching candidate event

When the driver (or most likely firmware) decides which AP to use
for roaming based on internal scan result processing, user space
needs to be notified of PMKSA caching candidates to allow RSN
pre-authentication to be used.

Signed-off-by: Jouni Malinen <[e-mail]>
Signed-off-by: John W. Linville <[e-mail]>

include/linux/nl80211.h

···
  *	this command may also be sent by the driver as an MLME event to
  *	inform userspace of the new replay counter.
  *
+ * @NL80211_CMD_PMKSA_CANDIDATE: This is used as an event to inform userspace
+ *	of PMKSA caching dandidates.
+ *
  * @NL80211_CMD_MAX: highest used command number
  * @__NL80211_CMD_AFTER_LAST: internal use
  */
···
 	NL80211_CMD_SCHED_SCAN_STOPPED,
 
 	NL80211_CMD_SET_REKEY_OFFLOAD,
+
+	NL80211_CMD_PMKSA_CANDIDATE,
 
 	/* add new commands above here */
 
···
  * @NL80211_ATTR_ROAM_SUPPORT: Indicates whether the firmware is capable of
  *	roaming to another AP in the same ESS if the signal lever is low.
  *
+ * @NL80211_ATTR_PMKSA_CANDIDATE: Nested attribute containing the PMKSA caching
+ *	candidate information, see &enum nl80211_pmksa_candidate_attr.
+ *
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
  */
···
 
 	NL80211_ATTR_SCHED_SCAN_MATCH,
 	NL80211_ATTR_MAX_MATCH_SETS,
+
+	NL80211_ATTR_PMKSA_CANDIDATE,
 
 	/* add attributes here, update the policy in nl80211.c */
 
···
 	/* keep last */
 	__NL80211_STA_WME_AFTER_LAST,
 	NL80211_STA_WME_MAX = __NL80211_STA_WME_AFTER_LAST - 1
+};
+
+/**
+ * enum nl80211_pmksa_candidate_attr - attributes for PMKSA caching candidates
+ * @__NL80211_PMKSA_CANDIDATE_INVALID: invalid number for nested attributes
+ * @NL80211_PMKSA_CANDIDATE_INDEX: candidate index (u32; the smaller, the higher
+ *	priority)
+ * @NL80211_PMKSA_CANDIDATE_BSSID: candidate BSSID (6 octets)
+ * @NL80211_PMKSA_CANDIDATE_PREAUTH: RSN pre-authentication supported (flag)
+ * @NUM_NL80211_PMKSA_CANDIDATE: number of PMKSA caching candidate attributes
+ *	(internal)
+ * @MAX_NL80211_PMKSA_CANDIDATE: highest PMKSA caching candidate attribute
+ *	(internal)
+ */
+enum nl80211_pmksa_candidate_attr {
+	__NL80211_PMKSA_CANDIDATE_INVALID,
+	NL80211_PMKSA_CANDIDATE_INDEX,
+	NL80211_PMKSA_CANDIDATE_BSSID,
+	NL80211_PMKSA_CANDIDATE_PREAUTH,
+
+	/* keep last */
+	NUM_NL80211_PMKSA_CANDIDATE,
+	MAX_NL80211_PMKSA_CANDIDATE = NUM_NL80211_PMKSA_CANDIDATE - 1
 };
 
 #endif /* __LINUX_NL80211_H */

include/net/cfg80211.h

···
 void cfg80211_gtk_rekey_notify(struct net_device *dev, const u8 *bssid,
 			       const u8 *replay_ctr, gfp_t gfp);
 
+/**
+ * cfg80211_pmksa_candidate_notify - notify about PMKSA caching candidate
+ * @dev: network device
+ * @index: candidate index (the smaller the index, the higher the priority)
+ * @bssid: BSSID of AP
+ * @preauth: Whether AP advertises support for RSN pre-authentication
+ * @gfp: allocation flags
+ */
+void cfg80211_pmksa_candidate_notify(struct net_device *dev, int index,
+				     const u8 *bssid, bool preauth, gfp_t gfp);
+
 /* Logging, debugging and troubleshooting/diagnostic helpers. */
 
 /* wiphy_printk helpers, similar to dev_printk */

net/wireless/mlme.c

···
 	nl80211_gtk_rekey_notify(rdev, dev, bssid, replay_ctr, gfp);
 }
 EXPORT_SYMBOL(cfg80211_gtk_rekey_notify);
+
+void cfg80211_pmksa_candidate_notify(struct net_device *dev, int index,
+				     const u8 *bssid, bool preauth, gfp_t gfp)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct wiphy *wiphy = wdev->wiphy;
+	struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);
+
+	nl80211_pmksa_candidate_notify(rdev, dev, index, bssid, preauth, gfp);
+}
+EXPORT_SYMBOL(cfg80211_pmksa_candidate_notify);

net/wireless/nl80211.c

···
 	nlmsg_free(msg);
 }
 
+void nl80211_pmksa_candidate_notify(struct cfg80211_registered_device *rdev,
+				    struct net_device *netdev, int index,
+				    const u8 *bssid, bool preauth, gfp_t gfp)
+{
+	struct sk_buff *msg;
+	struct nlattr *attr;
+	void *hdr;
+
+	msg = nlmsg_new(NLMSG_GOODSIZE, gfp);
+	if (!msg)
+		return;
+
+	hdr = nl80211hdr_put(msg, 0, 0, 0, NL80211_CMD_PMKSA_CANDIDATE);
+	if (!hdr) {
+		nlmsg_free(msg);
+		return;
+	}
+
+	NLA_PUT_U32(msg, NL80211_ATTR_WIPHY, rdev->wiphy_idx);
+	NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, netdev->ifindex);
+
+	attr = nla_nest_start(msg, NL80211_ATTR_PMKSA_CANDIDATE);
+	if (!attr)
+		goto nla_put_failure;
+
+	NLA_PUT_U32(msg, NL80211_PMKSA_CANDIDATE_INDEX, index);
+	NLA_PUT(msg, NL80211_PMKSA_CANDIDATE_BSSID, ETH_ALEN, bssid);
+	if (preauth)
+		NLA_PUT_FLAG(msg, NL80211_PMKSA_CANDIDATE_PREAUTH);
+
+	nla_nest_end(msg, attr);
+
+	if (genlmsg_end(msg, hdr) < 0) {
+		nlmsg_free(msg);
+		return;
+	}
+
+	genlmsg_multicast_netns(wiphy_net(&rdev->wiphy), msg, 0,
+				nl80211_mlme_mcgrp.id, gfp);
+	return;
+
+ nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	nlmsg_free(msg);
+}
+
 void
 nl80211_send_cqm_pktloss_notify(struct cfg80211_registered_device *rdev,
 				struct net_device *netdev, const u8 *peer,

net/wireless/nl80211.h

···
 			      struct net_device *netdev, const u8 *bssid,
 			      const u8 *replay_ctr, gfp_t gfp);
 
+void nl80211_pmksa_candidate_notify(struct cfg80211_registered_device *rdev,
+				    struct net_device *netdev, int index,
+				    const u8 *bssid, bool preauth, gfp_t gfp);
+
 #endif /* __NET_WIRELESS_NL80211_H */