Merge branch 'netlink_ext_ACK'

Johannes Berg says:

====================
netlink extended ACK reporting

Changes since v4:
 * use __NLMSGERR_ATTR_MAX instead of NUM_NLMSGERR_ATTRS

Changes since v3:
 * Add NLM_F_CAPPED and NLM_F_ACK_TLVS flags, to allow entirely
   stateless parsing of the ACK messages by looking at the new
   flags. Need to check NLM_F_ACK_TLVS first, since capping can
   be done in kernels before this patchset without setting the
   flag.
 * Remove "missing_attr" functionality - this can obviously be
   added back rather easily, but I'd rather have more discussion
   about the nesting problem there.
 * Improve documentation of NLMSGERR_ATTR_OFFS
 * Improve message structure documentation, documenting that the
   request message is always capped for success cases
 * fix nlmsg_len of the outer message by calling nlmsg_end()
 * fix memcpy() of the request in success cases, going back to
   the original code that I'd changed before due to the payload
   adjustments that I reverted when introducing tlvlen

Changes since v2:
 * add NUM_NLMSGERR_ATTRS, NLMSGERR_ATTR_MAX
 * fix cookie length to 20 (sha-1 length)
 * move struct members for cookie to patch 3 where they should be
 * another cleanup suggested by David Ahern

Changes since v1:
 * credit Pablo and Jamal
 * incorporate suggestion from David Ahern
 * fix compilation in decnet
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

crypto/crypto_user.c

@@ -483,7 +483,8 @@ static const struct crypto_link {
 	[CRYPTO_MSG_DELRNG	- CRYPTO_MSG_BASE] = { .doit = crypto_del_rng },
 };
 
-static int crypto_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
+static int crypto_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
+			       struct netlink_ext_ack *extack)
 {
 	struct nlattr *attrs[CRYPTOCFGA_MAX+1];
 	const struct crypto_link *link;
@@ -522,7 +523,7 @@ static int crypto_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 	}
 
 	err = nlmsg_parse(nlh, crypto_msg_min[type], attrs, CRYPTOCFGA_MAX,
-			  crypto_policy);
+			  crypto_policy, extack);
 	if (err < 0)
 		return err;
 

drivers/block/drbd/drbd_nla.c

@@ -34,7 +34,7 @@ int drbd_nla_parse_nested(struct nlattr *tb[], int maxtype, struct nlattr *nla,
 
 	err = drbd_nla_check_mandatory(maxtype, nla);
 	if (!err)
-		err = nla_parse_nested(tb, maxtype, nla, policy);
+		err = nla_parse_nested(tb, maxtype, nla, policy, NULL);
 
 	return err;
 }

drivers/infiniband/core/addr.c

@@ -88,7 +88,7 @@ static inline bool ib_nl_is_good_ip_resp(const struct nlmsghdr *nlh)
 		return false;
 
 	ret = nla_parse(tb, LS_NLA_TYPE_MAX - 1, nlmsg_data(nlh),
-			nlmsg_len(nlh), ib_nl_addr_policy);
+			nlmsg_len(nlh), ib_nl_addr_policy, NULL);
 	if (ret)
 		return false;
 

drivers/infiniband/core/iwpm_util.c

@@ -472,12 +472,14 @@ int iwpm_parse_nlmsg(struct netlink_callback *cb, int policy_max,
 	int ret;
 	const char *err_str = "";
 
-	ret = nlmsg_validate(cb->nlh, nlh_len, policy_max-1, nlmsg_policy);
+	ret = nlmsg_validate(cb->nlh, nlh_len, policy_max - 1, nlmsg_policy,
+			     NULL);
 	if (ret) {
 		err_str = "Invalid attribute";
 		goto parse_nlmsg_error;
 	}
-	ret = nlmsg_parse(cb->nlh, nlh_len, nltb, policy_max-1, nlmsg_policy);
+	ret = nlmsg_parse(cb->nlh, nlh_len, nltb, policy_max - 1,
+			  nlmsg_policy, NULL);
 	if (ret) {
 		err_str = "Unable to parse the nlmsg";
 		goto parse_nlmsg_error;

drivers/infiniband/core/netlink.c

@@ -146,7 +146,8 @@ int ibnl_put_attr(struct sk_buff *skb, struct nlmsghdr *nlh,
 }
 EXPORT_SYMBOL(ibnl_put_attr);
 
-static int ibnl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
+static int ibnl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
+			struct netlink_ext_ack *extack)
 {
 	struct ibnl_client *client;
 	int type = nlh->nlmsg_type;
@@ -209,7 +210,7 @@ static void ibnl_rcv_reply_skb(struct sk_buff *skb)
 		if (nlh->nlmsg_flags & NLM_F_REQUEST)
 			return;
 
-		ibnl_rcv_msg(skb, nlh);
+		ibnl_rcv_msg(skb, nlh, NULL);
 
 		msglen = NLMSG_ALIGN(nlh->nlmsg_len);
 		if (msglen > skb->len)

drivers/infiniband/core/sa_query.c

@@ -808,7 +808,7 @@ int ib_nl_handle_set_timeout(struct sk_buff *skb,
 		return -EPERM;
 
 	ret = nla_parse(tb, LS_NLA_TYPE_MAX - 1, nlmsg_data(nlh),
-			nlmsg_len(nlh), ib_nl_policy);
+			nlmsg_len(nlh), ib_nl_policy, NULL);
 	attr = (const struct nlattr *)tb[LS_NLA_TYPE_TIMEOUT];
 	if (ret || !attr)
 		goto settimeout_out;
@@ -860,7 +860,7 @@ static inline int ib_nl_is_good_resolve_resp(const struct nlmsghdr *nlh)
 		return 0;
 
 	ret = nla_parse(tb, LS_NLA_TYPE_MAX - 1, nlmsg_data(nlh),
-			nlmsg_len(nlh), ib_nl_policy);
+			nlmsg_len(nlh), ib_nl_policy, NULL);
 	if (ret)
 		return 0;
 

drivers/net/macsec.c

@@ -1590,8 +1590,9 @@ static int parse_sa_config(struct nlattr **attrs, struct nlattr **tb_sa)
 	if (!attrs[MACSEC_ATTR_SA_CONFIG])
 		return -EINVAL;
 
-	if (nla_parse_nested(tb_sa, MACSEC_SA_ATTR_MAX, attrs[MACSEC_ATTR_SA_CONFIG],
-			     macsec_genl_sa_policy))
+	if (nla_parse_nested(tb_sa, MACSEC_SA_ATTR_MAX,
+			     attrs[MACSEC_ATTR_SA_CONFIG],
+			     macsec_genl_sa_policy, NULL))
 		return -EINVAL;
 
 	return 0;
@@ -1602,8 +1603,9 @@ static int parse_rxsc_config(struct nlattr **attrs, struct nlattr **tb_rxsc)
 	if (!attrs[MACSEC_ATTR_RXSC_CONFIG])
 		return -EINVAL;
 
-	if (nla_parse_nested(tb_rxsc, MACSEC_RXSC_ATTR_MAX, attrs[MACSEC_ATTR_RXSC_CONFIG],
-			     macsec_genl_rxsc_policy))
+	if (nla_parse_nested(tb_rxsc, MACSEC_RXSC_ATTR_MAX,
+			     attrs[MACSEC_ATTR_RXSC_CONFIG],
+			     macsec_genl_rxsc_policy, NULL))
 		return -EINVAL;
 
 	return 0;

drivers/net/team/team.c

@@ -2471,7 +2471,8 @@ static int team_nl_cmd_options_set(struct sk_buff *skb, struct genl_info *info)
 			goto team_put;
 		}
 		err = nla_parse_nested(opt_attrs, TEAM_ATTR_OPTION_MAX,
-				       nl_option, team_nl_option_policy);
+				       nl_option, team_nl_option_policy,
+				       info->extack);
 		if (err)
 			goto team_put;
 		if (!opt_attrs[TEAM_ATTR_OPTION_NAME] ||

drivers/net/veth.c

@@ -368,7 +368,8 @@ static int veth_newlink(struct net *src_net, struct net_device *dev,
 		ifmp = nla_data(nla_peer);
 		err = rtnl_nla_parse_ifla(peer_tb,
 					  nla_data(nla_peer) + sizeof(struct ifinfomsg),
-					  nla_len(nla_peer) - sizeof(struct ifinfomsg));
+					  nla_len(nla_peer) - sizeof(struct ifinfomsg),
+					  NULL);
 		if (err < 0)
 			return err;
 

drivers/net/wireless/ath/ath10k/testmode.c

@@ -420,8 +420,8 @@ int ath10k_tm_cmd(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 	struct nlattr *tb[ATH10K_TM_ATTR_MAX + 1];
 	int ret;
 
-	ret = nla_parse(tb, ATH10K_TM_ATTR_MAX, data, len,
-			ath10k_tm_policy);
+	ret = nla_parse(tb, ATH10K_TM_ATTR_MAX, data, len, ath10k_tm_policy,
+			NULL);
 	if (ret)
 		return ret;
 

drivers/net/wireless/ath/ath6kl/testmode.c

@@ -74,8 +74,8 @@ int ath6kl_tm_cmd(struct wiphy *wiphy, struct wireless_dev *wdev,
 	int err, buf_len;
 	void *buf;
 
-	err = nla_parse(tb, ATH6KL_TM_ATTR_MAX, data, len,
-			ath6kl_tm_policy);
+	err = nla_parse(tb, ATH6KL_TM_ATTR_MAX, data, len, ath6kl_tm_policy,
+			NULL);
 	if (err)
 		return err;
 

drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c

@@ -3711,7 +3711,8 @@ static int __iwl_mvm_mac_testmode_cmd(struct iwl_mvm *mvm,
 	int err;
 	u32 noa_duration;
 
-	err = nla_parse(tb, IWL_MVM_TM_ATTR_MAX, data, len, iwl_mvm_tm_policy);
+	err = nla_parse(tb, IWL_MVM_TM_ATTR_MAX, data, len, iwl_mvm_tm_policy,
+			NULL);
 	if (err)
 		return err;
 

drivers/net/wireless/mac80211_hwsim.c

@@ -389,7 +389,7 @@ static int mac80211_hwsim_vendor_cmd_test(struct wiphy *wiphy,
 	u32 val;
 
 	err = nla_parse(tb, QCA_WLAN_VENDOR_ATTR_MAX, data, data_len,
-			hwsim_vendor_test_policy);
+			hwsim_vendor_test_policy, NULL);
 	if (err)
 		return err;
 	if (!tb[QCA_WLAN_VENDOR_ATTR_TEST])
@@ -1852,7 +1852,7 @@ static int mac80211_hwsim_testmode_cmd(struct ieee80211_hw *hw,
 	int err, ps;
 
 	err = nla_parse(tb, HWSIM_TM_ATTR_MAX, data, len,
-			hwsim_testmode_policy);
+			hwsim_testmode_policy, NULL);
 	if (err)
 		return err;
 

drivers/net/wireless/marvell/mwifiex/cfg80211.c

@@ -4016,8 +4016,8 @@ static int mwifiex_tm_cmd(struct wiphy *wiphy, struct wireless_dev *wdev,
 	if (!priv)
 		return -EINVAL;
 
-	err = nla_parse(tb, MWIFIEX_TM_ATTR_MAX, data, len,
-			mwifiex_tm_policy);
+	err = nla_parse(tb, MWIFIEX_TM_ATTR_MAX, data, len, mwifiex_tm_policy,
+			NULL);
 	if (err)
 		return err;
 

drivers/net/wireless/ti/wlcore/testmode.c

@@ -366,7 +366,8 @@ int wl1271_tm_cmd(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 	u32 nla_cmd;
 	int err;
 
-	err = nla_parse(tb, WL1271_TM_ATTR_MAX, data, len, wl1271_tm_policy);
+	err = nla_parse(tb, WL1271_TM_ATTR_MAX, data, len, wl1271_tm_policy,
+			NULL);
 	if (err)
 		return err;
 

drivers/net/wireless/ti/wlcore/vendor_cmd.c

@@ -41,7 +41,7 @@ wlcore_vendor_cmd_smart_config_start(struct wiphy *wiphy,
 		return -EINVAL;
 
 	ret = nla_parse(tb, MAX_WLCORE_VENDOR_ATTR, data, data_len,
-			wlcore_vendor_attr_policy);
+			wlcore_vendor_attr_policy, NULL);
 	if (ret)
 		return ret;
 
@@ -116,7 +116,7 @@ wlcore_vendor_cmd_smart_config_set_group_key(struct wiphy *wiphy,
 		return -EINVAL;
 
 	ret = nla_parse(tb, MAX_WLCORE_VENDOR_ATTR, data, data_len,
-			wlcore_vendor_attr_policy);
+			wlcore_vendor_attr_policy, NULL);
 	if (ret)
 		return ret;
 

drivers/scsi/scsi_netlink.c

@@ -111,7 +111,7 @@ scsi_nl_rcv_msg(struct sk_buff *skb)
 
 next_msg:
 		if ((err) || (nlh->nlmsg_flags & NLM_F_ACK))
-			netlink_ack(skb, nlh, err);
+			netlink_ack(skb, nlh, err, NULL);
 
 		skb_pull(skb, rlen);
 	}

include/linux/netlink.h

@@ -62,11 +62,42 @@ netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg)
 	return __netlink_kernel_create(net, unit, THIS_MODULE, cfg);
 }
 
+/* this can be increased when necessary - don't expose to userland */
+#define NETLINK_MAX_COOKIE_LEN	20
+
+/**
+ * struct netlink_ext_ack - netlink extended ACK report struct
+ * @_msg: message string to report - don't access directly, use
+ *	%NL_SET_ERR_MSG
+ * @bad_attr: attribute with error
+ * @cookie: cookie data to return to userspace (for success)
+ * @cookie_len: actual cookie data length
+ */
+struct netlink_ext_ack {
+	const char *_msg;
+	const struct nlattr *bad_attr;
+	u8 cookie[NETLINK_MAX_COOKIE_LEN];
+	u8 cookie_len;
+};
+
+/* Always use this macro, this allows later putting the
+ * message into a separate section or such for things
+ * like translation or listing all possible messages.
+ * Currently string formatting is not supported (due
+ * to the lack of an output buffer.)
+ */
+#define NL_SET_ERR_MSG(extack, msg) do {	\
+	static const char _msg[] = (msg);	\
+						\
+	(extack)->_msg = _msg;			\
+} while (0)
+
 extern void netlink_kernel_release(struct sock *sk);
 extern int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
 extern int netlink_change_ngroups(struct sock *sk, unsigned int groups);
 extern void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
-extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err);
+extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
+			const struct netlink_ext_ack *extack);
 extern int netlink_has_listeners(struct sock *sk, unsigned int group);
 
 extern int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);

include/net/genetlink.h

@@ -84,6 +84,7 @@ struct nlattr **genl_family_attrbuf(const struct genl_family *family);
  * @attrs: netlink attributes
  * @_net: network namespace
  * @user_ptr: user pointers
+ * @extack: extended ACK report struct
  */
 struct genl_info {
 	u32			snd_seq;
@@ -94,6 +95,7 @@ struct genl_info {
 	struct nlattr **	attrs;
 	possible_net_t		_net;
 	void *			user_ptr[2];
+	struct netlink_ext_ack *extack;
 };
 
 static inline struct net *genl_info_net(struct genl_info *info)
@@ -106,6 +108,16 @@ static inline void genl_info_net_set(struct genl_info *info, struct net *net)
 	write_pnet(&info->_net, net);
 }
 
+#define GENL_SET_ERR_MSG(info, msg) NL_SET_ERR_MSG((info)->extack, msg)
+
+static inline int genl_err_attr(struct genl_info *info, int err,
+				struct nlattr *attr)
+{
+	info->extack->bad_attr = attr;
+
+	return err;
+}
+
 /**
  * struct genl_ops - generic netlink operations
  * @cmd: command identifier
@@ -162,14 +174,16 @@ genlmsg_nlhdr(void *user_hdr, const struct genl_family *family)
  * @tb: destination array with maxtype+1 elements
  * @maxtype: maximum attribute type to be expected
  * @policy: validation policy
- * */
+ * @extack: extended ACK report struct
+ */
 static inline int genlmsg_parse(const struct nlmsghdr *nlh,
 				const struct genl_family *family,
 				struct nlattr *tb[], int maxtype,
-				const struct nla_policy *policy)
+				const struct nla_policy *policy,
+				struct netlink_ext_ack *extack)
 {
 	return nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype,
-			   policy);
+			   policy, extack);
 }
 
 /**