Commit 2dbba6f7 authored by Johannes Berg's avatar Johannes Berg Committed by David S. Miller

[GENETLINK]: Dynamic multicast groups.

Introduce API to dynamically register and unregister multicast groups.
Signed-off-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Acked-by: default avatarPatrick McHardy <kaber@trash.net>
Acked-by: default avatarJamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 84659eb5
......@@ -39,6 +39,9 @@ enum {
CTRL_CMD_NEWOPS,
CTRL_CMD_DELOPS,
CTRL_CMD_GETOPS,
CTRL_CMD_NEWMCAST_GRP,
CTRL_CMD_DELMCAST_GRP,
CTRL_CMD_GETMCAST_GRP, /* unused */
__CTRL_CMD_MAX,
};
......@@ -52,6 +55,7 @@ enum {
CTRL_ATTR_HDRSIZE,
CTRL_ATTR_MAXATTR,
CTRL_ATTR_OPS,
CTRL_ATTR_MCAST_GROUPS,
__CTRL_ATTR_MAX,
};
......@@ -66,4 +70,13 @@ enum {
#define CTRL_ATTR_OP_MAX (__CTRL_ATTR_OP_MAX - 1)
enum {
CTRL_ATTR_MCAST_GRP_UNSPEC,
CTRL_ATTR_MCAST_GRP_NAME,
CTRL_ATTR_MCAST_GRP_ID,
__CTRL_ATTR_MCAST_GRP_MAX,
};
#define CTRL_ATTR_MCAST_GRP_MAX (__CTRL_ATTR_MCAST_GRP_MAX - 1)
#endif /* __LINUX_GENERIC_NETLINK_H */
......@@ -4,6 +4,22 @@
#include <linux/genetlink.h>
#include <net/netlink.h>
/**
* struct genl_multicast_group - generic netlink multicast group
* @name: name of the multicast group, names are per-family
* @id: multicast group ID, assigned by the core, to use with
* genlmsg_multicast().
* @list: list entry for linking
* @family: pointer to family, need not be set before registering
*/
struct genl_multicast_group
{
struct genl_family *family; /* private */
struct list_head list; /* private */
char name[GENL_NAMSIZ];
u32 id;
};
/**
* struct genl_family - generic netlink family
* @id: protocol family idenfitier
......@@ -14,6 +30,7 @@
* @attrbuf: buffer to store parsed attributes
* @ops_list: list of all assigned operations
* @family_list: family list
* @mcast_groups: multicast groups list
*/
struct genl_family
{
......@@ -25,6 +42,7 @@ struct genl_family
struct nlattr ** attrbuf; /* private */
struct list_head ops_list; /* private */
struct list_head family_list; /* private */
struct list_head mcast_groups; /* private */
};
/**
......@@ -73,6 +91,10 @@ extern int genl_register_family(struct genl_family *family);
extern int genl_unregister_family(struct genl_family *family);
extern int genl_register_ops(struct genl_family *, struct genl_ops *ops);
extern int genl_unregister_ops(struct genl_family *, struct genl_ops *ops);
extern int genl_register_mc_group(struct genl_family *family,
struct genl_multicast_group *grp);
extern void genl_unregister_mc_group(struct genl_family *family,
struct genl_multicast_group *grp);
extern struct sock *genl_sock;
......
......@@ -3,6 +3,7 @@
*
* Authors: Jamal Hadi Salim
* Thomas Graf <tgraf@suug.ch>
* Johannes Berg <johannes@sipsolutions.net>
*/
#include <linux/module.h>
......@@ -13,6 +14,7 @@
#include <linux/string.h>
#include <linux/skbuff.h>
#include <linux/mutex.h>
#include <linux/bitmap.h>
#include <net/sock.h>
#include <net/genetlink.h>
......@@ -42,6 +44,16 @@ static void genl_unlock(void)
#define GENL_FAM_TAB_MASK (GENL_FAM_TAB_SIZE - 1)
static struct list_head family_ht[GENL_FAM_TAB_SIZE];
/*
* Bitmap of multicast groups that are currently in use.
*
* To avoid an allocation at boot of just one unsigned long,
* declare it global instead.
* Bit 0 is marked as already used since group 0 is invalid.
*/
static unsigned long mc_group_start = 0x1;
static unsigned long *mc_groups = &mc_group_start;
static unsigned long mc_groups_longs = 1;
static int genl_ctrl_event(int event, void *data);
......@@ -116,6 +128,114 @@ static inline u16 genl_generate_id(void)
return id_gen_idx;
}
static struct genl_multicast_group notify_grp;
/**
* genl_register_mc_group - register a multicast group
*
* Registers the specified multicast group and notifies userspace
* about the new group.
*
* Returns 0 on success or a negative error code.
*
* @family: The generic netlink family the group shall be registered for.
* @grp: The group to register, must have a name.
*/
int genl_register_mc_group(struct genl_family *family,
struct genl_multicast_group *grp)
{
int id;
unsigned long *new_groups;
int err;
BUG_ON(grp->name[0] == '\0');
genl_lock();
/* special-case our own group */
if (grp == &notify_grp)
id = GENL_ID_CTRL;
else
id = find_first_zero_bit(mc_groups,
mc_groups_longs * BITS_PER_LONG);
if (id >= mc_groups_longs * BITS_PER_LONG) {
size_t nlen = (mc_groups_longs + 1) * sizeof(unsigned long);
if (mc_groups == &mc_group_start) {
new_groups = kzalloc(nlen, GFP_KERNEL);
if (!new_groups) {
err = -ENOMEM;
goto out;
}
mc_groups = new_groups;
*mc_groups = mc_group_start;
} else {
new_groups = krealloc(mc_groups, nlen, GFP_KERNEL);
if (!new_groups) {
err = -ENOMEM;
goto out;
}
mc_groups = new_groups;
mc_groups[mc_groups_longs] = 0;
}
mc_groups_longs++;
}
err = netlink_change_ngroups(genl_sock,
sizeof(unsigned long) * NETLINK_GENERIC);
if (err)
goto out;
grp->id = id;
set_bit(id, mc_groups);
list_add_tail(&grp->list, &family->mcast_groups);
grp->family = family;
genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, grp);
out:
genl_unlock();
return 0;
}
EXPORT_SYMBOL(genl_register_mc_group);
/**
* genl_unregister_mc_group - unregister a multicast group
*
* Unregisters the specified multicast group and notifies userspace
* about it. All current listeners on the group are removed.
*
* Note: It is not necessary to unregister all multicast groups before
* unregistering the family, unregistering the family will cause
* all assigned multicast groups to be unregistered automatically.
*
* @family: Generic netlink family the group belongs to.
* @grp: The group to unregister, must have been registered successfully
* previously.
*/
void genl_unregister_mc_group(struct genl_family *family,
struct genl_multicast_group *grp)
{
BUG_ON(grp->family != family);
genl_lock();
netlink_clear_multicast_users(genl_sock, grp->id);
clear_bit(grp->id, mc_groups);
list_del(&grp->list);
genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, grp);
grp->id = 0;
grp->family = NULL;
genl_unlock();
}
static void genl_unregister_mc_groups(struct genl_family *family)
{
struct genl_multicast_group *grp, *tmp;
list_for_each_entry_safe(grp, tmp, &family->mcast_groups, list)
genl_unregister_mc_group(family, grp);
}
/**
* genl_register_ops - register generic netlink operations
* @family: generic netlink family
......@@ -216,6 +336,7 @@ int genl_register_family(struct genl_family *family)
goto errout;
INIT_LIST_HEAD(&family->ops_list);
INIT_LIST_HEAD(&family->mcast_groups);
genl_lock();
......@@ -275,6 +396,8 @@ int genl_unregister_family(struct genl_family *family)
{
struct genl_family *rc;
genl_unregister_mc_groups(family);
genl_lock();
list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
......@@ -410,6 +533,67 @@ static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
nla_nest_end(skb, nla_ops);
}
if (!list_empty(&family->mcast_groups)) {
struct genl_multicast_group *grp;
struct nlattr *nla_grps;
int idx = 1;
nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
if (nla_grps == NULL)
goto nla_put_failure;
list_for_each_entry(grp, &family->mcast_groups, list) {
struct nlattr *nest;
nest = nla_nest_start(skb, idx++);
if (nest == NULL)
goto nla_put_failure;
NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
grp->name);
nla_nest_end(skb, nest);
}
nla_nest_end(skb, nla_grps);
}
return genlmsg_end(skb, hdr);
nla_put_failure:
return genlmsg_cancel(skb, hdr);
}
static int ctrl_fill_mcgrp_info(struct genl_multicast_group *grp, u32 pid,
u32 seq, u32 flags, struct sk_buff *skb,
u8 cmd)
{
void *hdr;
struct nlattr *nla_grps;
struct nlattr *nest;
hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
if (hdr == NULL)
return -1;
NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, grp->family->name);
NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, grp->family->id);
nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
if (nla_grps == NULL)
goto nla_put_failure;
nest = nla_nest_start(skb, 1);
if (nest == NULL)
goto nla_put_failure;
NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
grp->name);
nla_nest_end(skb, nest);
nla_nest_end(skb, nla_grps);
return genlmsg_end(skb, hdr);
nla_put_failure:
......@@ -453,8 +637,8 @@ static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
return skb->len;
}
static struct sk_buff *ctrl_build_msg(struct genl_family *family, u32 pid,
int seq, u8 cmd)
static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
u32 pid, int seq, u8 cmd)
{
struct sk_buff *skb;
int err;
......@@ -472,6 +656,25 @@ static struct sk_buff *ctrl_build_msg(struct genl_family *family, u32 pid,
return skb;
}
static struct sk_buff *ctrl_build_mcgrp_msg(struct genl_multicast_group *grp,
u32 pid, int seq, u8 cmd)
{
struct sk_buff *skb;
int err;
skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
if (skb == NULL)
return ERR_PTR(-ENOBUFS);
err = ctrl_fill_mcgrp_info(grp, pid, seq, 0, skb, cmd);
if (err < 0) {
nlmsg_free(skb);
return ERR_PTR(err);
}
return skb;
}
static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
[CTRL_ATTR_FAMILY_ID] = { .type = NLA_U16 },
[CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
......@@ -501,8 +704,8 @@ static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
goto errout;
}
msg = ctrl_build_msg(res, info->snd_pid, info->snd_seq,
CTRL_CMD_NEWFAMILY);
msg = ctrl_build_family_msg(res, info->snd_pid, info->snd_seq,
CTRL_CMD_NEWFAMILY);
if (IS_ERR(msg)) {
err = PTR_ERR(msg);
goto errout;
......@@ -523,7 +726,15 @@ static int genl_ctrl_event(int event, void *data)
switch (event) {
case CTRL_CMD_NEWFAMILY:
case CTRL_CMD_DELFAMILY:
msg = ctrl_build_msg(data, 0, 0, event);
msg = ctrl_build_family_msg(data, 0, 0, event);
if (IS_ERR(msg))
return PTR_ERR(msg);
genlmsg_multicast(msg, 0, GENL_ID_CTRL, GFP_KERNEL);
break;
case CTRL_CMD_NEWMCAST_GRP:
case CTRL_CMD_DELMCAST_GRP:
msg = ctrl_build_mcgrp_msg(data, 0, 0, event);
if (IS_ERR(msg))
return PTR_ERR(msg);
......@@ -541,6 +752,10 @@ static struct genl_ops genl_ctrl_ops = {
.policy = ctrl_policy,
};
static struct genl_multicast_group notify_grp = {
.name = "notify",
};
static int __init genl_init(void)
{
int i, err;
......@@ -557,11 +772,17 @@ static int __init genl_init(void)
goto errout_register;
netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV);
genl_sock = netlink_kernel_create(NETLINK_GENERIC, GENL_MAX_ID,
genl_rcv, NULL, THIS_MODULE);
/* we'll bump the group number right afterwards */
genl_sock = netlink_kernel_create(NETLINK_GENERIC, 0, genl_rcv,
NULL, THIS_MODULE);
if (genl_sock == NULL)
panic("GENL: Cannot initialize generic netlink\n");
err = genl_register_mc_group(&genl_ctrl, &notify_grp);
if (err < 0)
goto errout_register;
return 0;
errout_register:
......
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