[B.A.T.M.A.N.] [RFC v4 03/19] batman-adv: Prepare framework for hardif genl config

Sven Eckelmann
2019-01-19T15:56:10Z

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
slave/hard-interface have B.A.T.M.A.N. V specific configuration settings.
The genl interface reflects this by allowing to get/set it using the
hard-interface specific commands.

The BATADV_CMD_GET_HARDIFS (or short version BATADV_CMD_GET_HARDIF) is
reused as get command because it already allow sto dump the content of
other information from the slave/hard-interface which are not yet
configuration specific.

The set command BATADV_CMD_SET_HARDIF will also notify interested userspace
listeners of the "config" mcast group using the BATADV_CMD_SET_HARDIF
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 | 16 ++-
net/batman-adv/netlink.c | 240 +++++++++++++++++++++++++++++---
2 files changed, 233 insertions(+), 23 deletions(-)

diff --git a/include/uapi/linux/batman_adv.h b/include/uapi/linux/batman_adv.h
index b3394aac..62456a08 100644
--- a/include/uapi/linux/batman_adv.h
+++ b/include/uapi/linux/batman_adv.h
@@ -398,9 +398,15 @@ enum batadv_nl_commands {
BATADV_CMD_GET_ROUTING_ALGOS,

/**
- * @BATADV_CMD_GET_HARDIFS: Query list of hard interfaces
+ * @BATADV_CMD_GET_HARDIF: Get attributes from a hardif of the
+ * current softif
*/
- BATADV_CMD_GET_HARDIFS,
+ BATADV_CMD_GET_HARDIF,
+
+ /**
+ * @BATADV_CMD_GET_HARDIFS: Alias for @BATADV_CMD_GET_HARDIF
+ */
+ BATADV_CMD_GET_HARDIFS = BATADV_CMD_GET_HARDIF,

/**
* @BATADV_CMD_GET_TRANSTABLE_LOCAL: Query list of local translations
@@ -453,6 +459,12 @@ enum batadv_nl_commands {
*/
BATADV_CMD_SET_MESH,

+ /**
+ * @BATADV_CMD_SET_HARDIF: Set attributes for hardif of the
+ * current softif
+ */
+ BATADV_CMD_SET_HARDIF,
+
/* add new commands above here */

/**
diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c
index ceec52aa..a58b5ecc 100644
--- a/net/batman-adv/netlink.c
+++ b/net/batman-adv/netlink.c
@@ -21,6 +21,7 @@

#include <linux/atomic.h>
#include <linux/bitops.h>
+#include <linux/bug.h>
#include <linux/byteorder/generic.h>
#include <linux/cache.h>
#include <linux/err.h>
@@ -76,6 +77,13 @@ enum batadv_genl_ops_flags {
* saved in info->user_ptr[0]
*/
BATADV_FLAG_NEED_MESH = BIT(0),
+
+ /**
+ * @BATADV_FLAG_NEED_HARDIF: request requires valid hard interface in
+ * attribute BATADV_ATTR_HARD_IFINDEX and expects a pointer to it to be
+ * saved in info->user_ptr[1]
+ */
+ BATADV_FLAG_NEED_HARDIF = BIT(1),
};

static const struct genl_multicast_group batadv_netlink_mcgrps[] = {
@@ -446,29 +454,38 @@ batadv_netlink_tp_meter_cancel(struct sk_buff *skb, struct genl_info *info)
}

/**
- * batadv_netlink_dump_hardif_entry() - Dump one hard interface into a message
+ * batadv_netlink_hardif_put() - Fill message with hardif attributes
* @msg: Netlink message to dump into
+ * @bat_priv: the bat priv with all the soft interface information
+ * @hard_iface: hard interface which was modified
+ * @cmd: type of message to generate
* @portid: Port making netlink request
+ * @seq: sequence number for message
+ * @flags: Additional flags for message
* @cb: Control block containing additional options
- * @hard_iface: Hard interface to dump
*
- * Return: error code, or 0 on success
+ * Return: 0 on success or negative error number in case of failure
*/
-static int
-batadv_netlink_dump_hardif_entry(struct sk_buff *msg, u32 portid,
- struct netlink_callback *cb,
- struct batadv_hard_iface *hard_iface)
+static int batadv_netlink_hardif_put(struct sk_buff *msg,
+ struct batadv_priv *bat_priv,
+ struct batadv_hard_iface *hard_iface,
+ enum batadv_nl_commands cmd,
+ u32 portid, u32 seq, int flags,
+ struct netlink_callback *cb)
{
struct net_device *net_dev = hard_iface->net_dev;
void *hdr;

- hdr = genlmsg_put(msg, portid, cb->nlh->nlmsg_seq,
- &batadv_netlink_family, NLM_F_MULTI,
- BATADV_CMD_GET_HARDIFS);
+ hdr = genlmsg_put(msg, portid, seq, &batadv_netlink_family, flags, cmd);
if (!hdr)
- return -EMSGSIZE;
+ return -ENOBUFS;
+
+ if (cb)
+ genl_dump_check_consistent(cb, hdr);

- genl_dump_check_consistent(cb, hdr);
+ 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_HARD_IFINDEX,
net_dev->ifindex) ||
@@ -486,24 +503,107 @@ batadv_netlink_dump_hardif_entry(struct sk_buff *msg, u32 portid,
genlmsg_end(msg, hdr);
return 0;

- nla_put_failure:
+nla_put_failure:
genlmsg_cancel(msg, hdr);
return -EMSGSIZE;
}

/**
- * batadv_netlink_dump_hardifs() - Dump all hard interface into a messages
+ * batadv_netlink_notify_hardif() - send hardif attributes to listener
+ * @bat_priv: the bat priv with all the soft interface information
+ * @hard_iface: hard interface which was modified
+ *
+ * Return: 0 on success, < 0 on error
+ */
+static int batadv_netlink_notify_hardif(struct batadv_priv *bat_priv,
+ struct batadv_hard_iface *hard_iface)
+{
+ struct sk_buff *msg;
+ int ret;
+
+ msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+ if (!msg)
+ return -ENOMEM;
+
+ ret = batadv_netlink_hardif_put(msg, bat_priv, hard_iface,
+ BATADV_CMD_SET_HARDIF, 0, 0, 0, NULL);
+ 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_hardif() - Get hardif 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_hardif(struct sk_buff *skb,
+ struct genl_info *info)
+{
+ struct batadv_hard_iface *hard_iface = 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_hardif_put(msg, bat_priv, hard_iface,
+ BATADV_CMD_GET_HARDIF,
+ info->snd_portid, info->snd_seq, 0,
+ NULL);
+ if (ret < 0) {
+ nlmsg_free(msg);
+ return ret;
+ }
+
+ ret = genlmsg_reply(msg, info);
+
+ return ret;
+}
+
+/**
+ * batadv_netlink_set_hardif() - Set hardif 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_hardif(struct sk_buff *skb,
+ struct genl_info *info)
+{
+ struct batadv_hard_iface *hard_iface = info->user_ptr[1];
+ struct batadv_priv *bat_priv = info->user_ptr[0];
+
+ batadv_netlink_notify_hardif(bat_priv, hard_iface);
+
+ return 0;
+}
+
+/**
+ * batadv_netlink_dump_hardif() - Dump all hard interface into a messages
* @msg: Netlink message to dump into
* @cb: Parameters from query
*
* Return: error code, or length of reply message on success
*/
static int
-batadv_netlink_dump_hardifs(struct sk_buff *msg, struct netlink_callback *cb)
+batadv_netlink_dump_hardif(struct sk_buff *msg, struct netlink_callback *cb)
{
struct net *net = sock_net(cb->skb->sk);
struct net_device *soft_iface;
struct batadv_hard_iface *hard_iface;
+ struct batadv_priv *bat_priv;
int ifindex;
int portid = NETLINK_CB(cb->skb).portid;
int skip = cb->args[0];
@@ -523,6 +623,8 @@ batadv_netlink_dump_hardifs(struct sk_buff *msg, struct netlink_callback *cb)
return -ENODEV;
}

+ bat_priv = netdev_priv(soft_iface);
+
rtnl_lock();
cb->seq = batadv_hardif_generation << 1 | 1;

@@ -533,8 +635,10 @@ batadv_netlink_dump_hardifs(struct sk_buff *msg, struct netlink_callback *cb)
if (i++ < skip)
continue;

- if (batadv_netlink_dump_hardif_entry(msg, portid, cb,
- hard_iface)) {
+ if (batadv_netlink_hardif_put(msg, bat_priv, hard_iface,
+ BATADV_CMD_GET_HARDIF,
+ portid, cb->nlh->nlmsg_seq,
+ NLM_F_MULTI, cb)) {
i--;
break;
}
@@ -583,6 +687,52 @@ batadv_get_softif_from_info(struct net *net, struct genl_info *info)
return ERR_PTR(-EINVAL);
}

+/**
+ * batadv_get_hardif_from_info() - Retrieve hardif 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 hard interface (with increased refcnt) on success, error
+ * pointer on error
+ */
+static struct batadv_hard_iface *
+batadv_get_hardif_from_info(struct batadv_priv *bat_priv, struct net *net,
+ struct genl_info *info)
+{
+ struct batadv_hard_iface *hard_iface;
+ struct net_device *hard_dev;
+ unsigned int hardif_index;
+
+ if (!info->attrs[BATADV_ATTR_HARD_IFINDEX])
+ return ERR_PTR(-EINVAL);
+
+ hardif_index = nla_get_u32(info->attrs[BATADV_ATTR_HARD_IFINDEX]);
+
+ hard_dev = dev_get_by_index(net, hardif_index);
+ if (!hard_dev)
+ return ERR_PTR(-ENODEV);
+
+ hard_iface = batadv_hardif_get_by_netdev(hard_dev);
+ if (!hard_iface)
+ goto err_put_harddev;
+
+ if (hard_iface->soft_iface != bat_priv->soft_iface)
+ goto err_put_hardif;
+
+ /* hard_dev is referenced by hard_iface and not needed here */
+ dev_put(hard_dev);
+
+ return hard_iface;
+
+err_put_hardif:
+ batadv_hardif_put(hard_iface);
+err_put_harddev:
+ dev_put(hard_dev);
+
+ return ERR_PTR(-EINVAL);
+}
+
/**
* batadv_pre_doit() - Prepare batman-adv genl doit request
* @ops: requested netlink operation
@@ -595,8 +745,21 @@ static int batadv_pre_doit(const struct genl_ops *ops, struct sk_buff *skb,
struct genl_info *info)
{
struct net *net = genl_info_net(info);
+ struct batadv_hard_iface *hard_iface;
+ struct batadv_priv *bat_priv = NULL;
struct net_device *soft_iface;
- struct batadv_priv *bat_priv;
+ u8 user_ptr1_flags;
+ u8 mesh_dep_flags;
+ int ret;
+
+ user_ptr1_flags = BATADV_FLAG_NEED_HARDIF;
+ if (WARN_ON(hweight8(ops->internal_flags & user_ptr1_flags) > 1))
+ return -EINVAL;
+
+ mesh_dep_flags = BATADV_FLAG_NEED_HARDIF;
+ if (WARN_ON((ops->internal_flags & mesh_dep_flags) &&
+ (~ops->internal_flags & BATADV_FLAG_NEED_MESH)))
+ return -EINVAL;

if (ops->internal_flags & BATADV_FLAG_NEED_MESH) {
soft_iface = batadv_get_softif_from_info(net, info);
@@ -607,7 +770,23 @@ static int batadv_pre_doit(const struct genl_ops *ops, struct sk_buff *skb,
info->user_ptr[0] = bat_priv;
}

+ if (ops->internal_flags & BATADV_FLAG_NEED_HARDIF) {
+ hard_iface = batadv_get_hardif_from_info(bat_priv, net, info);
+ if (IS_ERR(hard_iface)) {
+ ret = PTR_ERR(hard_iface);
+ goto err_put_softif;
+ }
+
+ info->user_ptr[1] = hard_iface;
+ }
+
return 0;
+
+err_put_softif:
+ if (bat_priv)
+ dev_put(bat_priv->soft_iface);
+
+ return ret;
}

/**
@@ -619,8 +798,16 @@ static int batadv_pre_doit(const struct genl_ops *ops, struct sk_buff *skb,
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_priv *bat_priv;

+ if (ops->internal_flags & BATADV_FLAG_NEED_HARDIF &&
+ info->user_ptr[1]) {
+ hard_iface = info->user_ptr[1];
+
+ batadv_hardif_put(hard_iface);
+ }
+
if (ops->internal_flags & BATADV_FLAG_NEED_MESH && info->user_ptr[0]) {
bat_priv = info->user_ptr[0];
dev_put(bat_priv->soft_iface);
@@ -656,10 +843,13 @@ static const struct genl_ops batadv_netlink_ops[] = {
.dumpit = batadv_algo_dump,
},
{
- .cmd = BATADV_CMD_GET_HARDIFS,
- .flags = GENL_ADMIN_PERM,
+ .cmd = BATADV_CMD_GET_HARDIF,
+ /* can be retrieved by unprivileged users */
.policy = batadv_netlink_policy,
- .dumpit = batadv_netlink_dump_hardifs,
+ .dumpit = batadv_netlink_dump_hardif,
+ .doit = batadv_netlink_get_hardif,
+ .internal_flags = BATADV_FLAG_NEED_MESH |
+ BATADV_FLAG_NEED_HARDIF,
},
{
.cmd = BATADV_CMD_GET_TRANSTABLE_LOCAL,
@@ -722,6 +912,14 @@ static const struct genl_ops batadv_netlink_ops[] = {
.doit = batadv_netlink_set_mesh,
.internal_flags = BATADV_FLAG_NEED_MESH,
},
+ {
+ .cmd = BATADV_CMD_SET_HARDIF,
+ .flags = GENL_ADMIN_PERM,
+ .policy = batadv_netlink_policy,
+ .doit = batadv_netlink_set_hardif,
+ .internal_flags = BATADV_FLAG_NEED_MESH |
+ BATADV_FLAG_NEED_HARDIF,
+ },
};

struct genl_family batadv_netlink_family __ro_after_init = {
--
2.20.1