genetlink.c

linux 内核源代码

	genl_unregister_mc_groups(family);

	genl_lock();

	list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
		if (family->id != rc->id || strcmp(rc->name, family->name))
			continue;

		list_del(&rc->family_list);
		INIT_LIST_HEAD(&family->ops_list);
		genl_unlock();

		kfree(family->attrbuf);
		genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
		return 0;
	}

	genl_unlock();

	return -ENOENT;
}

static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
	struct genl_ops *ops;
	struct genl_family *family;
	struct genl_info info;
	struct genlmsghdr *hdr = nlmsg_data(nlh);
	int hdrlen, err;

	family = genl_family_find_byid(nlh->nlmsg_type);
	if (family == NULL)
		return -ENOENT;

	hdrlen = GENL_HDRLEN + family->hdrsize;
	if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
		return -EINVAL;

	ops = genl_get_cmd(hdr->cmd, family);
	if (ops == NULL)
		return -EOPNOTSUPP;

	if ((ops->flags & GENL_ADMIN_PERM) &&
	    security_netlink_recv(skb, CAP_NET_ADMIN))
		return -EPERM;

	if (nlh->nlmsg_flags & NLM_F_DUMP) {
		if (ops->dumpit == NULL)
			return -EOPNOTSUPP;

		return netlink_dump_start(genl_sock, skb, nlh,
					  ops->dumpit, ops->done);
	}

	if (ops->doit == NULL)
		return -EOPNOTSUPP;

	if (family->attrbuf) {
		err = nlmsg_parse(nlh, hdrlen, family->attrbuf, family->maxattr,
				  ops->policy);
		if (err < 0)
			return err;
	}

	info.snd_seq = nlh->nlmsg_seq;
	info.snd_pid = NETLINK_CB(skb).pid;
	info.nlhdr = nlh;
	info.genlhdr = nlmsg_data(nlh);
	info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
	info.attrs = family->attrbuf;

	return ops->doit(skb, &info);
}

static void genl_rcv(struct sk_buff *skb)
{
	genl_lock();
	netlink_rcv_skb(skb, &genl_rcv_msg);
	genl_unlock();
}

/**************************************************************************
 * Controller
 **************************************************************************/

static struct genl_family genl_ctrl = {
	.id = GENL_ID_CTRL,
	.name = "nlctrl",
	.version = 0x2,
	.maxattr = CTRL_ATTR_MAX,
};

static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
			  u32 flags, struct sk_buff *skb, u8 cmd)
{
	void *hdr;

	hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
	if (hdr == NULL)
		return -1;

	NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, family->name);
	NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, family->id);
	NLA_PUT_U32(skb, CTRL_ATTR_VERSION, family->version);
	NLA_PUT_U32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize);
	NLA_PUT_U32(skb, CTRL_ATTR_MAXATTR, family->maxattr);

	if (!list_empty(&family->ops_list)) {
		struct nlattr *nla_ops;
		struct genl_ops *ops;
		int idx = 1;

		nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
		if (nla_ops == NULL)
			goto nla_put_failure;

		list_for_each_entry(ops, &family->ops_list, ops_list) {
			struct nlattr *nest;

			nest = nla_nest_start(skb, idx++);
			if (nest == NULL)
				goto nla_put_failure;

			NLA_PUT_U32(skb, CTRL_ATTR_OP_ID, ops->cmd);
			NLA_PUT_U32(skb, CTRL_ATTR_OP_FLAGS, ops->flags);

			nla_nest_end(skb, nest);
		}

		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:
	return genlmsg_cancel(skb, hdr);
}

static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
{

	int i, n = 0;
	struct genl_family *rt;
	int chains_to_skip = cb->args[0];
	int fams_to_skip = cb->args[1];

	if (chains_to_skip != 0)
		genl_lock();

	for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
		if (i < chains_to_skip)
			continue;
		n = 0;
		list_for_each_entry(rt, genl_family_chain(i), family_list) {
			if (++n < fams_to_skip)
				continue;
			if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).pid,
					   cb->nlh->nlmsg_seq, NLM_F_MULTI,
					   skb, CTRL_CMD_NEWFAMILY) < 0)
				goto errout;
		}

		fams_to_skip = 0;
	}

errout:
	if (chains_to_skip != 0)
		genl_unlock();

	cb->args[0] = i;
	cb->args[1] = n;

	return skb->len;
}

static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
					     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_info(family, pid, seq, 0, skb, cmd);
	if (err < 0) {
		nlmsg_free(skb);
		return ERR_PTR(err);
	}

	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,
				    .len = GENL_NAMSIZ - 1 },
};

static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
{
	struct sk_buff *msg;
	struct genl_family *res = NULL;
	int err = -EINVAL;

	if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
		u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
		res = genl_family_find_byid(id);
	}

	if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
		char *name;

		name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
		res = genl_family_find_byname(name);
	}

	if (res == NULL) {
		err = -ENOENT;
		goto errout;
	}

	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;
	}

	err = genlmsg_reply(msg, info);
errout:
	return err;
}

static int genl_ctrl_event(int event, void *data)
{
	struct sk_buff *msg;

	if (genl_sock == NULL)
		return 0;

	switch (event) {
	case CTRL_CMD_NEWFAMILY:
	case CTRL_CMD_DELFAMILY:
		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);

		genlmsg_multicast(msg, 0, GENL_ID_CTRL, GFP_KERNEL);
		break;
	}

	return 0;
}

static struct genl_ops genl_ctrl_ops = {
	.cmd		= CTRL_CMD_GETFAMILY,
	.doit		= ctrl_getfamily,
	.dumpit		= ctrl_dumpfamily,
	.policy		= ctrl_policy,
};

static struct genl_multicast_group notify_grp = {
	.name		= "notify",
};

static int __init genl_init(void)
{
	int i, err;

	for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
		INIT_LIST_HEAD(&family_ht[i]);

	err = genl_register_family(&genl_ctrl);
	if (err < 0)
		goto errout;

	err = genl_register_ops(&genl_ctrl, &genl_ctrl_ops);
	if (err < 0)
		goto errout_register;

	netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV);

	/* we'll bump the group number right afterwards */
	genl_sock = netlink_kernel_create(&init_net, 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:
	genl_unregister_family(&genl_ctrl);
errout:
	panic("GENL: Cannot register controller: %d\n", err);
}

subsys_initcall(genl_init);

EXPORT_SYMBOL(genl_sock);
EXPORT_SYMBOL(genl_register_ops);
EXPORT_SYMBOL(genl_unregister_ops);
EXPORT_SYMBOL(genl_register_family);
EXPORT_SYMBOL(genl_unregister_family);