[GENETLINK]: Dynamic multicast groups.
Introduce API to dynamically register and unregister multicast groups. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Acked-by: Patrick McHardy <kaber@trash.net> Acked-by: Jamal Hadi Salim <hadi@cyberus.ca> Signed-off-by: David S. Miller <davem@davemloft.net>hifive-unleashed-5.1
Johannes Berg
David S. Miller
parent
84659eb529
commit
2dbba6f773
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@ -39,6 +39,9 @@ enum {
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CTRL_CMD_NEWOPS,
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CTRL_CMD_DELOPS,
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CTRL_CMD_GETOPS,
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CTRL_CMD_NEWMCAST_GRP,
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CTRL_CMD_DELMCAST_GRP,
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CTRL_CMD_GETMCAST_GRP, /* unused */
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__CTRL_CMD_MAX,
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};
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@ -52,6 +55,7 @@ enum {
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CTRL_ATTR_HDRSIZE,
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CTRL_ATTR_MAXATTR,
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CTRL_ATTR_OPS,
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CTRL_ATTR_MCAST_GROUPS,
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__CTRL_ATTR_MAX,
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};
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@ -66,4 +70,13 @@ enum {
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#define CTRL_ATTR_OP_MAX (__CTRL_ATTR_OP_MAX - 1)
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enum {
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CTRL_ATTR_MCAST_GRP_UNSPEC,
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CTRL_ATTR_MCAST_GRP_NAME,
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CTRL_ATTR_MCAST_GRP_ID,
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__CTRL_ATTR_MCAST_GRP_MAX,
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};
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#define CTRL_ATTR_MCAST_GRP_MAX (__CTRL_ATTR_MCAST_GRP_MAX - 1)
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#endif /* __LINUX_GENERIC_NETLINK_H */
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@ -4,6 +4,22 @@
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#include <linux/genetlink.h>
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#include <net/netlink.h>
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/**
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* struct genl_multicast_group - generic netlink multicast group
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* @name: name of the multicast group, names are per-family
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* @id: multicast group ID, assigned by the core, to use with
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* genlmsg_multicast().
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* @list: list entry for linking
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* @family: pointer to family, need not be set before registering
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*/
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struct genl_multicast_group
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{
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struct genl_family *family; /* private */
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struct list_head list; /* private */
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char name[GENL_NAMSIZ];
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u32 id;
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};
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/**
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* struct genl_family - generic netlink family
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* @id: protocol family idenfitier
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@ -14,6 +30,7 @@
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* @attrbuf: buffer to store parsed attributes
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* @ops_list: list of all assigned operations
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* @family_list: family list
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* @mcast_groups: multicast groups list
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*/
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struct genl_family
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{
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@ -25,6 +42,7 @@ struct genl_family
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struct nlattr ** attrbuf; /* private */
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struct list_head ops_list; /* private */
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struct list_head family_list; /* private */
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struct list_head mcast_groups; /* private */
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};
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/**
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@ -73,6 +91,10 @@ extern int genl_register_family(struct genl_family *family);
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extern int genl_unregister_family(struct genl_family *family);
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extern int genl_register_ops(struct genl_family *, struct genl_ops *ops);
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extern int genl_unregister_ops(struct genl_family *, struct genl_ops *ops);
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extern int genl_register_mc_group(struct genl_family *family,
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struct genl_multicast_group *grp);
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extern void genl_unregister_mc_group(struct genl_family *family,
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struct genl_multicast_group *grp);
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extern struct sock *genl_sock;
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@ -3,6 +3,7 @@
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*
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* Authors: Jamal Hadi Salim
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* Thomas Graf <tgraf@suug.ch>
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* Johannes Berg <johannes@sipsolutions.net>
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*/
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#include <linux/module.h>
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@ -13,6 +14,7 @@
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#include <linux/string.h>
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#include <linux/skbuff.h>
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#include <linux/mutex.h>
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#include <linux/bitmap.h>
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#include <net/sock.h>
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#include <net/genetlink.h>
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@ -42,6 +44,16 @@ static void genl_unlock(void)
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#define GENL_FAM_TAB_MASK (GENL_FAM_TAB_SIZE - 1)
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static struct list_head family_ht[GENL_FAM_TAB_SIZE];
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/*
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* Bitmap of multicast groups that are currently in use.
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*
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* To avoid an allocation at boot of just one unsigned long,
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* declare it global instead.
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* Bit 0 is marked as already used since group 0 is invalid.
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*/
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static unsigned long mc_group_start = 0x1;
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static unsigned long *mc_groups = &mc_group_start;
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static unsigned long mc_groups_longs = 1;
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static int genl_ctrl_event(int event, void *data);
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@ -116,6 +128,114 @@ static inline u16 genl_generate_id(void)
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return id_gen_idx;
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}
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static struct genl_multicast_group notify_grp;
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/**
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* genl_register_mc_group - register a multicast group
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*
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* Registers the specified multicast group and notifies userspace
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* about the new group.
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*
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* Returns 0 on success or a negative error code.
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*
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* @family: The generic netlink family the group shall be registered for.
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* @grp: The group to register, must have a name.
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*/
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int genl_register_mc_group(struct genl_family *family,
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struct genl_multicast_group *grp)
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{
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int id;
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unsigned long *new_groups;
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int err;
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BUG_ON(grp->name[0] == '\0');
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genl_lock();
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/* special-case our own group */
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if (grp == ¬ify_grp)
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id = GENL_ID_CTRL;
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else
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id = find_first_zero_bit(mc_groups,
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mc_groups_longs * BITS_PER_LONG);
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if (id >= mc_groups_longs * BITS_PER_LONG) {
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size_t nlen = (mc_groups_longs + 1) * sizeof(unsigned long);
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if (mc_groups == &mc_group_start) {
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new_groups = kzalloc(nlen, GFP_KERNEL);
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if (!new_groups) {
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err = -ENOMEM;
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goto out;
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}
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mc_groups = new_groups;
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*mc_groups = mc_group_start;
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} else {
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new_groups = krealloc(mc_groups, nlen, GFP_KERNEL);
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if (!new_groups) {
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err = -ENOMEM;
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goto out;
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}
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mc_groups = new_groups;
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mc_groups[mc_groups_longs] = 0;
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}
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mc_groups_longs++;
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}
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err = netlink_change_ngroups(genl_sock,
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sizeof(unsigned long) * NETLINK_GENERIC);
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if (err)
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goto out;
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grp->id = id;
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set_bit(id, mc_groups);
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list_add_tail(&grp->list, &family->mcast_groups);
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grp->family = family;
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genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, grp);
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out:
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genl_unlock();
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return 0;
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}
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EXPORT_SYMBOL(genl_register_mc_group);
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/**
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* genl_unregister_mc_group - unregister a multicast group
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*
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* Unregisters the specified multicast group and notifies userspace
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* about it. All current listeners on the group are removed.
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*
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* Note: It is not necessary to unregister all multicast groups before
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* unregistering the family, unregistering the family will cause
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* all assigned multicast groups to be unregistered automatically.
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*
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* @family: Generic netlink family the group belongs to.
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* @grp: The group to unregister, must have been registered successfully
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* previously.
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*/
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void genl_unregister_mc_group(struct genl_family *family,
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struct genl_multicast_group *grp)
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{
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BUG_ON(grp->family != family);
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genl_lock();
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netlink_clear_multicast_users(genl_sock, grp->id);
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clear_bit(grp->id, mc_groups);
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list_del(&grp->list);
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genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, grp);
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grp->id = 0;
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grp->family = NULL;
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genl_unlock();
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}
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static void genl_unregister_mc_groups(struct genl_family *family)
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{
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struct genl_multicast_group *grp, *tmp;
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list_for_each_entry_safe(grp, tmp, &family->mcast_groups, list)
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genl_unregister_mc_group(family, grp);
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}
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/**
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* genl_register_ops - register generic netlink operations
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* @family: generic netlink family
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@ -216,6 +336,7 @@ int genl_register_family(struct genl_family *family)
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goto errout;
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INIT_LIST_HEAD(&family->ops_list);
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INIT_LIST_HEAD(&family->mcast_groups);
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genl_lock();
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@ -275,6 +396,8 @@ int genl_unregister_family(struct genl_family *family)
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{
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struct genl_family *rc;
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genl_unregister_mc_groups(family);
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genl_lock();
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list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
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@ -410,6 +533,67 @@ static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
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nla_nest_end(skb, nla_ops);
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}
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if (!list_empty(&family->mcast_groups)) {
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struct genl_multicast_group *grp;
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struct nlattr *nla_grps;
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int idx = 1;
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nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
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if (nla_grps == NULL)
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goto nla_put_failure;
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list_for_each_entry(grp, &family->mcast_groups, list) {
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struct nlattr *nest;
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nest = nla_nest_start(skb, idx++);
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if (nest == NULL)
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goto nla_put_failure;
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NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
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NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
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grp->name);
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nla_nest_end(skb, nest);
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}
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nla_nest_end(skb, nla_grps);
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}
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return genlmsg_end(skb, hdr);
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nla_put_failure:
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return genlmsg_cancel(skb, hdr);
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}
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static int ctrl_fill_mcgrp_info(struct genl_multicast_group *grp, u32 pid,
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u32 seq, u32 flags, struct sk_buff *skb,
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u8 cmd)
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{
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void *hdr;
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struct nlattr *nla_grps;
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struct nlattr *nest;
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hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
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if (hdr == NULL)
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return -1;
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NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, grp->family->name);
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NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, grp->family->id);
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nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
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if (nla_grps == NULL)
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goto nla_put_failure;
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nest = nla_nest_start(skb, 1);
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if (nest == NULL)
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goto nla_put_failure;
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NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
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NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
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grp->name);
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nla_nest_end(skb, nest);
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nla_nest_end(skb, nla_grps);
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return genlmsg_end(skb, hdr);
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nla_put_failure:
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@ -453,8 +637,8 @@ errout:
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return skb->len;
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}
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static struct sk_buff *ctrl_build_msg(struct genl_family *family, u32 pid,
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int seq, u8 cmd)
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static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
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u32 pid, int seq, u8 cmd)
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{
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struct sk_buff *skb;
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int err;
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@ -472,6 +656,25 @@ static struct sk_buff *ctrl_build_msg(struct genl_family *family, u32 pid,
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return skb;
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}
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static struct sk_buff *ctrl_build_mcgrp_msg(struct genl_multicast_group *grp,
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u32 pid, int seq, u8 cmd)
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{
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struct sk_buff *skb;
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int err;
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skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
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if (skb == NULL)
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return ERR_PTR(-ENOBUFS);
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err = ctrl_fill_mcgrp_info(grp, pid, seq, 0, skb, cmd);
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if (err < 0) {
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nlmsg_free(skb);
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return ERR_PTR(err);
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}
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return skb;
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}
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static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
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[CTRL_ATTR_FAMILY_ID] = { .type = NLA_U16 },
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[CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
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@ -501,8 +704,8 @@ static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
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goto errout;
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}
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msg = ctrl_build_msg(res, info->snd_pid, info->snd_seq,
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CTRL_CMD_NEWFAMILY);
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msg = ctrl_build_family_msg(res, info->snd_pid, info->snd_seq,
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CTRL_CMD_NEWFAMILY);
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if (IS_ERR(msg)) {
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err = PTR_ERR(msg);
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goto errout;
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@ -523,7 +726,15 @@ static int genl_ctrl_event(int event, void *data)
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switch (event) {
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case CTRL_CMD_NEWFAMILY:
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case CTRL_CMD_DELFAMILY:
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msg = ctrl_build_msg(data, 0, 0, event);
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msg = ctrl_build_family_msg(data, 0, 0, event);
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if (IS_ERR(msg))
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return PTR_ERR(msg);
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genlmsg_multicast(msg, 0, GENL_ID_CTRL, GFP_KERNEL);
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break;
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case CTRL_CMD_NEWMCAST_GRP:
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case CTRL_CMD_DELMCAST_GRP:
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msg = ctrl_build_mcgrp_msg(data, 0, 0, event);
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if (IS_ERR(msg))
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return PTR_ERR(msg);
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@ -541,6 +752,10 @@ static struct genl_ops genl_ctrl_ops = {
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.policy = ctrl_policy,
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};
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static struct genl_multicast_group notify_grp = {
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.name = "notify",
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};
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static int __init genl_init(void)
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{
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int i, err;
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@ -557,11 +772,17 @@ static int __init genl_init(void)
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goto errout_register;
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netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV);
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genl_sock = netlink_kernel_create(NETLINK_GENERIC, GENL_MAX_ID,
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genl_rcv, NULL, THIS_MODULE);
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/* we'll bump the group number right afterwards */
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genl_sock = netlink_kernel_create(NETLINK_GENERIC, 0, genl_rcv,
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NULL, THIS_MODULE);
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if (genl_sock == NULL)
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panic("GENL: Cannot initialize generic netlink\n");
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err = genl_register_mc_group(&genl_ctrl, ¬ify_grp);
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if (err < 0)
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goto errout_register;
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return 0;
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errout_register:
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