[PATCH v2 1/2] batman-adv: Prepare infrastructure for newlink settings

[PATCH v2 1/2] batman-adv: Prepare infrastructure for newlink settings

[Sven Eckelmann]

The batadv generic netlink family can be used to retrieve the current state
and set various configuration settings. But there are also settings which
must be set before the actual interface is created.

The rtnetlink already uses IFLA_INFO_DATA to allow net_device families to
transfer such configurations. The minimal required functionality for this
is now available for the batadv rtnl_link_ops. Also a new IFLA class of
attributes will be attached to it because rtnetlink only allows 51
different attributes but batadv_nl_attrs already contains 62 attributes.

Cc: Annika Wickert <annika.wickert@exaring.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
v2:
* don't use compat code for kernel 4.13 and 4.14

 compat.h                        | 11 ++++++++++
 include/uapi/linux/batman_adv.h | 20 +++++++++++++++++
 net/batman-adv/soft-interface.c | 39 +++++++++++++++++++++++++++++++++
 3 files changed, 70 insertions(+)

diff --git a/compat.h b/compat.h
index e3220e39..9da9feb7 100644
--- a/compat.h
+++ b/compat.h
@@ -15,6 +15,17 @@
 
 #include "compat-autoconf.h"
 
+#if LINUX_VERSION_IS_LESS(4, 13, 0)
+
+#define batadv_softif_validate(__tb, __data, __extack) \
+	batadv_softif_validate(__tb, __data)
+
+#define batadv_softif_newlink(__src_net, __dev, __tb, __data, __extack) \
+	batadv_softif_newlink(__src_net, __dev, __tb, __data)
+
+#endif /* LINUX_VERSION_IS_LESS(4, 13, 0) */
+
+
 #if LINUX_VERSION_IS_LESS(4, 15, 0)
 
 #define batadv_softif_slave_add(__dev, __slave_dev, __extack) \
diff --git a/include/uapi/linux/batman_adv.h b/include/uapi/linux/batman_adv.h
index bb0ae945..b05399d8 100644
--- a/include/uapi/linux/batman_adv.h
+++ b/include/uapi/linux/batman_adv.h
@@ -675,4 +675,24 @@ enum batadv_tp_meter_reason {
 	BATADV_TP_REASON_TOO_MANY		= 133,
 };
 
+/**
+ * enum batadv_ifla_attrs - batman-adv ifla nested attributes
+ */
+enum batadv_ifla_attrs {
+	/**
+	 * @IFLA_BATADV_UNSPEC: unspecified attribute which is not parsed by
+	 *  rtnetlink
+	 */
+	IFLA_BATADV_UNSPEC,
+
+	/* add attributes above here, update the policy in soft-interface.c */
+
+	/**
+	 * @__IFLA_BATADV_MAX: internal use
+	 */
+	__IFLA_BATADV_MAX,
+};
+
+#define IFLA_BATADV_MAX (__IFLA_BATADV_MAX - 1)
+
 #endif /* _UAPI_LINUX_BATMAN_ADV_H_ */
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 82e7ca88..9c7b8968 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -38,6 +38,7 @@
 #include <linux/stddef.h>
 #include <linux/string.h>
 #include <linux/types.h>
+#include <net/netlink.h>
 #include <uapi/linux/batadv_packet.h>
 #include <uapi/linux/batman_adv.h>
 
@@ -1073,6 +1074,37 @@ static void batadv_softif_init_early(struct net_device *dev)
 	dev->ethtool_ops = &batadv_ethtool_ops;
 }
 
+/**
+ * batadv_softif_validate() - validate configuration of new batadv link
+ * @tb: IFLA_INFO_DATA netlink attributes
+ * @data: enum batadv_ifla_attrs attributes
+ * @extack: extended ACK report struct
+ *
+ * Return: 0 if successful or error otherwise.
+ */
+static int batadv_softif_validate(struct nlattr *tb[], struct nlattr *data[],
+				  struct netlink_ext_ack *extack)
+{
+	return 0;
+}
+
+/**
+ * batadv_softif_newlink() - pre-initialize and register new batadv link
+ * @src_net: the applicable net namespace
+ * @dev: network device to register
+ * @tb: IFLA_INFO_DATA netlink attributes
+ * @data: enum batadv_ifla_attrs attributes
+ * @extack: extended ACK report struct
+ *
+ * Return: 0 if successful or error otherwise.
+ */
+static int batadv_softif_newlink(struct net *src_net, struct net_device *dev,
+				 struct nlattr *tb[], struct nlattr *data[],
+				 struct netlink_ext_ack *extack)
+{
+	return register_netdevice(dev);
+}
+
 /**
  * batadv_softif_create() - Create and register soft interface
  * @net: the applicable net namespace
@@ -1171,9 +1203,16 @@ bool batadv_softif_is_valid(const struct net_device *net_dev)
 	return false;
 }
 
+static const struct nla_policy batadv_ifla_policy[IFLA_BATADV_MAX + 1] = {
+};
+
 struct rtnl_link_ops batadv_link_ops __read_mostly = {
 	.kind		= "batadv",
 	.priv_size	= sizeof(struct batadv_priv),
 	.setup		= batadv_softif_init_early,
+	.maxtype	= IFLA_BATADV_MAX,
+	.policy		= batadv_ifla_policy,
+	.validate	= batadv_softif_validate,
+	.newlink	= batadv_softif_newlink,
 	.dellink	= batadv_softif_destroy_netlink,
 };
-- 
2.28.0

[PATCH v2 2/2] batman-adv: Allow selection of routing algorithm over rtnetlink

[Sven Eckelmann]

A batadv net_device is associated to a B.A.T.M.A.N. routing algorithm. This
algorithm has to be selected before the interface is initialized and cannot
be changed after that. The only way to select this algorithm was a module
parameter which specifies the default algorithm used during the creation of
the net_device.

This module parameter is writeable over
/sys/module/batman_adv/parameters/routing_algo and thus allows switching of
the routing algorithm:

1. change routing_algo parameter
2. create new batadv net_device

But this is not race free because another process can be scheduled between
1 + 2 and in that time frame change the routing_algo parameter again.

It is much cleaner to directly provide this information inside the
rtnetlink's RTM_NEWLINK message. The two processes would be (in regards of
the creation parameter of their batadv interfaces) be isolated. This also
eases the integration of batadv devices inside tools like network-manager
or systemd-networkd which are not expecting to operate on /sys before a new
net_device is created.

Cc: Annika Wickert <annika.wickert@exaring.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 include/uapi/linux/batman_adv.h |  6 ++++++
 net/batman-adv/bat_algo.c       | 10 ++++++++--
 net/batman-adv/bat_algo.h       |  3 ++-
 net/batman-adv/soft-interface.c | 34 ++++++++++++++++++++++++++++++---
 4 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/include/uapi/linux/batman_adv.h b/include/uapi/linux/batman_adv.h
index b05399d8..bdb317fa 100644
--- a/include/uapi/linux/batman_adv.h
+++ b/include/uapi/linux/batman_adv.h
@@ -685,6 +685,12 @@ enum batadv_ifla_attrs {
 	 */
 	IFLA_BATADV_UNSPEC,
 
+	/**
+	 * @IFLA_BATADV_ALGO_NAME: routing algorithm (name) which should be
+	 *  used by the newly registered batadv net_device.
+	 */
+	IFLA_BATADV_ALGO_NAME,
+
 	/* add attributes above here, update the policy in soft-interface.c */
 
 	/**
diff --git a/net/batman-adv/bat_algo.c b/net/batman-adv/bat_algo.c
index 382fbe51..500db94a 100644
--- a/net/batman-adv/bat_algo.c
+++ b/net/batman-adv/bat_algo.c
@@ -34,7 +34,13 @@ void batadv_algo_init(void)
 	INIT_HLIST_HEAD(&batadv_algo_list);
 }
 
-static struct batadv_algo_ops *batadv_algo_get(char *name)
+/**
+ * batadv_algo_get() - Search for algorithm with specific name
+ * @name: algorithm name to find
+ *
+ * Return: Pointer to batadv_algo_ops on success, NULL otherwise
+ */
+struct batadv_algo_ops *batadv_algo_get(const char *name)
 {
 	struct batadv_algo_ops *bat_algo_ops = NULL, *bat_algo_ops_tmp;
 
@@ -97,7 +103,7 @@ int batadv_algo_register(struct batadv_algo_ops *bat_algo_ops)
  *
  * Return: 0 on success or negative error number in case of failure
  */
-int batadv_algo_select(struct batadv_priv *bat_priv, char *name)
+int batadv_algo_select(struct batadv_priv *bat_priv, const char *name)
 {
 	struct batadv_algo_ops *bat_algo_ops;
 
diff --git a/net/batman-adv/bat_algo.h b/net/batman-adv/bat_algo.h
index 686a60bc..2ae140ea 100644
--- a/net/batman-adv/bat_algo.h
+++ b/net/batman-adv/bat_algo.h
@@ -18,8 +18,9 @@ extern char batadv_routing_algo[];
 extern struct list_head batadv_hardif_list;
 
 void batadv_algo_init(void);
+struct batadv_algo_ops *batadv_algo_get(const char *name);
 int batadv_algo_register(struct batadv_algo_ops *bat_algo_ops);
-int batadv_algo_select(struct batadv_priv *bat_priv, char *name);
+int batadv_algo_select(struct batadv_priv *bat_priv, const char *name);
 int batadv_algo_seq_print_text(struct seq_file *seq, void *offset);
 int batadv_algo_dump(struct sk_buff *msg, struct netlink_callback *cb);
 
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 9c7b8968..d96b4815 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -846,9 +846,11 @@ static int batadv_softif_init_late(struct net_device *dev)
 
 	batadv_nc_init_bat_priv(bat_priv);
 
-	ret = batadv_algo_select(bat_priv, batadv_routing_algo);
-	if (ret < 0)
-		goto free_bat_counters;
+	if (!bat_priv->algo_ops) {
+		ret = batadv_algo_select(bat_priv, batadv_routing_algo);
+		if (ret < 0)
+			goto free_bat_counters;
+	}
 
 	ret = batadv_debugfs_add_meshif(dev);
 	if (ret < 0)
@@ -1085,6 +1087,17 @@ static void batadv_softif_init_early(struct net_device *dev)
 static int batadv_softif_validate(struct nlattr *tb[], struct nlattr *data[],
 				  struct netlink_ext_ack *extack)
 {
+	struct batadv_algo_ops *algo_ops;
+
+	if (!data)
+		return 0;
+
+	if (data[IFLA_BATADV_ALGO_NAME]) {
+		algo_ops = batadv_algo_get(nla_data(data[IFLA_BATADV_ALGO_NAME]));
+		if (!algo_ops)
+			return -EINVAL;
+	}
+
 	return 0;
 }
 
@@ -1102,6 +1115,20 @@ static int batadv_softif_newlink(struct net *src_net, struct net_device *dev,
 				 struct nlattr *tb[], struct nlattr *data[],
 				 struct netlink_ext_ack *extack)
 {
+	struct batadv_priv *bat_priv = netdev_priv(dev);
+	const char *algo_name;
+	int err;
+
+	if (!data)
+		return 0;
+
+	if (data[IFLA_BATADV_ALGO_NAME]) {
+		algo_name = nla_data(data[IFLA_BATADV_ALGO_NAME]);
+		err = batadv_algo_select(bat_priv, algo_name);
+		if (err)
+			return -EINVAL;
+	}
+
 	return register_netdevice(dev);
 }
 
@@ -1204,6 +1231,7 @@ bool batadv_softif_is_valid(const struct net_device *net_dev)
 }
 
 static const struct nla_policy batadv_ifla_policy[IFLA_BATADV_MAX + 1] = {
+	[IFLA_BATADV_ALGO_NAME]	= { .type = NLA_NUL_STRING },
 };
 
 struct rtnl_link_ops batadv_link_ops __read_mostly = {
-- 
2.28.0