path: root/net/netlink/genetlink.c

/*
 * NETLINK      Generic Netlink Family
 *
 * 		Authors:	Jamal Hadi Salim
 * 				Thomas Graf <tgraf@suug.ch>
 *				Johannes Berg <johannes@sipsolutions.net>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/string.h>
#include <linux/skbuff.h>
#include <linux/mutex.h>
#include <linux/bitmap.h>
#include <linux/rwsem.h>
#include <net/sock.h>
#include <net/genetlink.h>

static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
static DECLARE_RWSEM(cb_lock);

void genl_lock(void)
{
	mutex_lock(&genl_mutex);
}
EXPORT_SYMBOL(genl_lock);

void genl_unlock(void)
{
	mutex_unlock(&genl_mutex);
}
EXPORT_SYMBOL(genl_unlock);

#ifdef CONFIG_LOCKDEP
int lockdep_genl_is_held(void)
{
	return lockdep_is_held(&genl_mutex);
}
EXPORT_SYMBOL(lockdep_genl_is_held);
#endif

static void genl_lock_all(void)
{
	down_write(&cb_lock);
	genl_lock();
}

static void genl_unlock_all(void)
{
	genl_unlock();
	up_write(&cb_lock);
}

#define GENL_FAM_TAB_SIZE	16
#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.
 * Bit 1 is marked as already used since the drop-monitor code
 * abuses the API and thinks it can statically use group 1.
 * That group will typically conflict with other groups that
 * any proper users use.
 * Bit 16 is marked as used since it's used for generic netlink
 * and the code no longer marks pre-reserved IDs as used.
 * Bit 17 is marked as already used since the VFS quota code
 * also abused this API and relied on family == group ID, we
 * cater to that by giving it a static family and group ID.
 * Bit 18 is marked as already used since the PMCRAID driver
 * did the same thing as the VFS quota code (maybe copied?)
 */
static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_CTRL) |
				      BIT(GENL_ID_VFS_DQUOT) |
				      BIT(GENL_ID_PMCRAID);
static unsigned long *mc_groups = &mc_group_start;
static unsigned long mc_groups_longs = 1;

static int genl_ctrl_event(int event, struct genl_family *family,
			   const struct genl_multicast_group *grp,
			   int grp_id);

static inline unsigned int genl_family_hash(unsigned int id)
{
	return id & GENL_FAM_TAB_MASK;
}

static inline struct list_head *genl_family_chain(unsigned int id)
{
	return &family_ht[genl_family_hash(id)];
}

static struct genl_family *genl_family_find_byid(unsigned int id)
{
	struct genl_family *f;

	list_for_each_entry(f, genl_family_chain(id), family_list)
		if (f->id == id)
			return f;

	return NULL;
}

static struct genl_family *genl_family_find_byname(char *name)
{
	struct genl_family *f;
	int i;

	for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
		list_for_each_entry(f, genl_family_chain(i), family_list)
			if (strcmp(f->name, name) == 0)
				return f;

	return NULL;
}

static const struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
{
	int i;

	for (i = 0; i < family->n_ops; i++)
		if (family->ops[i].cmd == cmd)
			return &family->ops[i];

	return NULL;
}

/* Of course we are going to have problems once we hit
 * 2^16 alive types, but that can only happen by year 2K
*/
static u16 genl_generate_id(void)
{
	static u16 id_gen_idx = GENL_MIN_ID;
	int i;

	for (i = 0; i <= GENL_MAX_ID - GENL_MIN_ID; i++) {
		if (id_gen_idx != GENL_ID_VFS_DQUOT &&
		    id_gen_idx != GENL_ID_PMCRAID &&
		    !genl_family_find_byid(id_gen_idx))
			return id_gen_idx;
		if (++id_gen_idx > GENL_MAX_ID)
			id_gen_idx = GENL_MIN_ID;
	}

	return 0;
}

static int