[B.A.T.M.A.N.] [RFC v4 04/19] batman-adv: Prepare framework for vlan genl config

Sven Eckelmann
2019-01-19T15:56:11Z

The batman-adv configuration interface was implemented solely using sysfs.
This approach was condemned by non-batadv developers as "huge mistake".
Instead a netlink/genl based implementation was suggested.

Beside the mesh/soft-interface specific configuration, the VLANs on top of
the mesh/soft-interface have configuration settings. The genl interface
reflects this by allowing to get/set it using the vlan specific commands
BATADV_CMD_GET_VLAN/BATADV_CMD_SET_VLAN.

The set command BATADV_CMD_SET_MESH will also notify interested userspace
listeners of the "config" mcast group using the BATADV_CMD_SET_VLAN command
message type that settings might have been changed and what the current
values are.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
include/uapi/linux/batman_adv.h | 17 +++
net/batman-adv/netlink.c | 191 +++++++++++++++++++++++++++++++-
2 files changed, 206 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/batman_adv.h b/include/uapi/linux/batman_adv.h
index 62456a08..10f3cc34 100644
--- a/include/uapi/linux/batman_adv.h
+++ b/include/uapi/linux/batman_adv.h
@@ -345,6 +345,11 @@ enum batadv_nl_attrs {
*/
BATADV_ATTR_MCAST_FLAGS_PRIV,

+ /**
+ * @BATADV_ATTR_VLANID: VLAN id on top of soft interface
+ */
+ BATADV_ATTR_VLANID,
+
/* add attributes above here, update the policy in netlink.c */

/**
@@ -465,6 +470,18 @@ enum batadv_nl_commands {
*/
BATADV_CMD_SET_HARDIF,

+ /**
+ * @BATADV_CMD_GET_VLAN: Get attributes from a VLAN of the
+ * current softif
+ */
+ BATADV_CMD_GET_VLAN,
+
+ /**
+ * @BATADV_CMD_SET_VLAN: Set attributes for VLAN of the
+ * current softif
+ */
+ BATADV_CMD_SET_VLAN,
+
/* add new commands above here */

/**
diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c
index a58b5ecc..e7a98c67 100644
--- a/net/batman-adv/netlink.c
+++ b/net/batman-adv/netlink.c
@@ -30,6 +30,7 @@
#include <linux/genetlink.h>
#include <linux/gfp.h>
#include <linux/if_ether.h>
+#include <linux/if_vlan.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
@@ -84,6 +85,13 @@ enum batadv_genl_ops_flags {
* saved in info->user_ptr[1]
*/
BATADV_FLAG_NEED_HARDIF = BIT(1),
+
+ /**
+ * @BATADV_FLAG_NEED_VLAN: request requires valid vlan in
+ * attribute BATADV_ATTR_VLANID and expects a pointer to it to be
+ * saved in info->user_ptr[1]
+ */
+ BATADV_FLAG_NEED_VLAN = BIT(2),
};

static const struct genl_multicast_group batadv_netlink_mcgrps[] = {
@@ -130,6 +138,7 @@ static const struct nla_policy batadv_netlink_policy[NUM_BATADV_ATTR] = {
[BATADV_ATTR_DAT_CACHE_VID] = { .type = NLA_U16 },
[BATADV_ATTR_MCAST_FLAGS] = { .type = NLA_U32 },
[BATADV_ATTR_MCAST_FLAGS_PRIV] = { .type = NLA_U32 },
+ [BATADV_ATTR_VLANID] = { .type = NLA_U16 },
};

/**
@@ -653,6 +662,123 @@ batadv_netlink_dump_hardif(struct sk_buff *msg, struct netlink_callback *cb)
return msg->len;
}

+/**
+ * batadv_netlink_vlan_put() - Fill message with vlan attributes
+ * @msg: Netlink message to dump into
+ * @bat_priv: the bat priv with all the soft interface information
+ * @vlan: vlan which was modified
+ * @cmd: type of message to generate
+ * @portid: Port making netlink request
+ * @seq: sequence number for message
+ * @flags: Additional flags for message
+ *
+ * Return: 0 on success or negative error number in case of failure
+ */
+static int batadv_netlink_vlan_put(struct sk_buff *msg,
+ struct batadv_priv *bat_priv,
+ struct batadv_softif_vlan *vlan,
+ enum batadv_nl_commands cmd,
+ u32 portid, u32 seq, int flags)
+{
+ void *hdr;
+
+ hdr = genlmsg_put(msg, portid, seq, &batadv_netlink_family, flags, cmd);
+ if (!hdr)
+ return -ENOBUFS;
+
+ if (nla_put_u32(msg, BATADV_ATTR_MESH_IFINDEX,
+ bat_priv->soft_iface->ifindex))
+ goto nla_put_failure;
+
+ if (nla_put_u32(msg, BATADV_ATTR_VLANID, vlan->vid & VLAN_VID_MASK))
+ goto nla_put_failure;
+
+ genlmsg_end(msg, hdr);
+ return 0;
+
+nla_put_failure:
+ genlmsg_cancel(msg, hdr);
+ return -EMSGSIZE;
+}
+
+/**
+ * batadv_netlink_notify_vlan() - send vlan attributes to listener
+ * @bat_priv: the bat priv with all the soft interface information
+ * @vlan: vlan which was modified
+ *
+ * Return: 0 on success, < 0 on error
+ */
+static int batadv_netlink_notify_vlan(struct batadv_priv *bat_priv,
+ struct batadv_softif_vlan *vlan)
+{
+ struct sk_buff *msg;
+ int ret;
+
+ msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+ if (!msg)
+ return -ENOMEM;
+
+ ret = batadv_netlink_vlan_put(msg, bat_priv, vlan,
+ BATADV_CMD_SET_VLAN, 0, 0, 0);
+ if (ret < 0) {
+ nlmsg_free(msg);
+ return ret;
+ }
+
+ genlmsg_multicast_netns(&batadv_netlink_family,
+ dev_net(bat_priv->soft_iface), msg, 0,
+ BATADV_NL_MCGRP_CONFIG, GFP_KERNEL);
+
+ return 0;
+}
+
+/**
+ * batadv_netlink_get_vlan() - Get vlan attributes
+ * @skb: Netlink message with request data
+ * @info: receiver information
+ *
+ * Return: 0 on success or negative error number in case of failure
+ */
+static int batadv_netlink_get_vlan(struct sk_buff *skb, struct genl_info *info)
+{
+ struct batadv_softif_vlan *vlan = info->user_ptr[1];
+ struct batadv_priv *bat_priv = info->user_ptr[0];
+ struct sk_buff *msg;
+ int ret;
+
+ msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+ if (!msg)
+ return -ENOMEM;
+
+ ret = batadv_netlink_vlan_put(msg, bat_priv, vlan, BATADV_CMD_GET_VLAN,
+ info->snd_portid, info->snd_seq, 0);
+ if (ret < 0) {
+ nlmsg_free(msg);
+ return ret;
+ }
+
+ ret = genlmsg_reply(msg, info);
+
+ return ret;
+}
+
+/**
+ * batadv_netlink_set_vlan() - Get vlan attributes
+ * @skb: Netlink message with request data
+ * @info: receiver information
+ *
+ * Return: 0 on success or negative error number in case of failure
+ */
+static int batadv_netlink_set_vlan(struct sk_buff *skb, struct genl_info *info)
+{
+ struct batadv_softif_vlan *vlan = info->user_ptr[1];
+ struct batadv_priv *bat_priv = info->user_ptr[0];
+
+ batadv_netlink_notify_vlan(bat_priv, vlan);
+
+ return 0;
+}
+
/**
* batadv_get_softif_from_info() - Retrieve soft interface from genl attributes
* @net: the applicable net namespace
@@ -733,6 +859,34 @@ batadv_get_hardif_from_info(struct batadv_priv *bat_priv, struct net *net,
return ERR_PTR(-EINVAL);
}

+/**
+ * batadv_get_vlan_from_info() - Retrieve vlan from genl attributes
+ * @bat_priv: the bat priv with all the soft interface information
+ * @net: the applicable net namespace
+ * @info: receiver information
+ *
+ * Return: Pointer to vlan on success (with increased refcnt), error pointer
+ * on error
+ */
+static struct batadv_softif_vlan *
+batadv_get_vlan_from_info(struct batadv_priv *bat_priv, struct net *net,
+ struct genl_info *info)
+{
+ struct batadv_softif_vlan *vlan;
+ u16 vid;
+
+ if (!info->attrs[BATADV_ATTR_VLANID])
+ return ERR_PTR(-EINVAL);
+
+ vid = nla_get_u16(info->attrs[BATADV_ATTR_VLANID]);
+
+ vlan = batadv_softif_vlan_get(bat_priv, vid | BATADV_VLAN_HAS_TAG);
+ if (!vlan)
+ return ERR_PTR(-ENOENT);
+
+ return vlan;
+}
+
/**
* batadv_pre_doit() - Prepare batman-adv genl doit request
* @ops: requested netlink operation
@@ -747,16 +901,17 @@ static int batadv_pre_doit(const struct genl_ops *ops, struct sk_buff *skb,
struct net *net = genl_info_net(info);
struct batadv_hard_iface *hard_iface;
struct batadv_priv *bat_priv = NULL;
+ struct batadv_softif_vlan *vlan;
struct net_device *soft_iface;
u8 user_ptr1_flags;
u8 mesh_dep_flags;
int ret;

- user_ptr1_flags = BATADV_FLAG_NEED_HARDIF;
+ user_ptr1_flags = BATADV_FLAG_NEED_HARDIF | BATADV_FLAG_NEED_VLAN;
if (WARN_ON(hweight8(ops->internal_flags & user_ptr1_flags) > 1))
return -EINVAL;

- mesh_dep_flags = BATADV_FLAG_NEED_HARDIF;
+ mesh_dep_flags = BATADV_FLAG_NEED_HARDIF | BATADV_FLAG_NEED_VLAN;
if (WARN_ON((ops->internal_flags & mesh_dep_flags) &&
(~ops->internal_flags & BATADV_FLAG_NEED_MESH)))
return -EINVAL;
@@ -780,6 +935,16 @@ static int batadv_pre_doit(const struct genl_ops *ops, struct sk_buff *skb,
info->user_ptr[1] = hard_iface;
}

+ if (ops->internal_flags & BATADV_FLAG_NEED_VLAN) {
+ vlan = batadv_get_vlan_from_info(bat_priv, net, info);
+ if (IS_ERR(vlan)) {
+ ret = PTR_ERR(vlan);
+ goto err_put_softif;
+ }
+
+ info->user_ptr[1] = vlan;
+ }
+
return 0;

err_put_softif:
@@ -799,6 +964,7 @@ static void batadv_post_doit(const struct genl_ops *ops, struct sk_buff *skb,
struct genl_info *info)
{
struct batadv_hard_iface *hard_iface;
+ struct batadv_softif_vlan *vlan;
struct batadv_priv *bat_priv;

if (ops->internal_flags & BATADV_FLAG_NEED_HARDIF &&
@@ -808,6 +974,11 @@ static void batadv_post_doit(const struct genl_ops *ops, struct sk_buff *skb,
batadv_hardif_put(hard_iface);
}

+ if (ops->internal_flags & BATADV_FLAG_NEED_VLAN && info->user_ptr[1]) {
+ vlan = info->user_ptr[1];
+ batadv_softif_vlan_put(vlan);
+ }
+
if (ops->internal_flags & BATADV_FLAG_NEED_MESH && info->user_ptr[0]) {
bat_priv = info->user_ptr[0];
dev_put(bat_priv->soft_iface);
@@ -920,6 +1091,22 @@ static const struct genl_ops batadv_netlink_ops[] = {
.internal_flags = BATADV_FLAG_NEED_MESH |
BATADV_FLAG_NEED_HARDIF,
},
+ {
+ .cmd = BATADV_CMD_GET_VLAN,
+ /* can be retrieved by unprivileged users */
+ .policy = batadv_netlink_policy,
+ .doit = batadv_netlink_get_vlan,
+ .internal_flags = BATADV_FLAG_NEED_MESH |
+ BATADV_FLAG_NEED_VLAN,
+ },
+ {
+ .cmd = BATADV_CMD_SET_VLAN,
+ .flags = GENL_ADMIN_PERM,
+ .policy = batadv_netlink_policy,
+ .doit = batadv_netlink_set_vlan,
+ .internal_flags = BATADV_FLAG_NEED_MESH |
+ BATADV_FLAG_NEED_VLAN,
+ },
};

struct genl_family batadv_netlink_family __ro_after_init = {
--
2.20.1