Commit a7311324 authored by Jiri Pirko's avatar Jiri Pirko Committed by Paolo Abeni
Browse files

genetlink: introduce per-sock family private storage 



Introduce an xarray for Generic netlink family to store per-socket
private. Initialize this xarray only if family uses per-socket privs.

Introduce genl_sk_priv_get() to get the socket priv pointer for a family
and initialize it in case it does not exist.
Introduce __genl_sk_priv_get() to obtain socket priv pointer for a
family under RCU read lock.

Allow family to specify the priv size, init() and destroy() callbacks.

Signed-off-by: default avatarJiri Pirko <jiri@nvidia.com>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 5648de0b

include/net/genetlink.h

+11 −0
Original line number Diff line number Diff line
@@ -51,6 +51,9 @@ struct genl_info; 
 * @split_ops: the split do/dump form of operation definition

 * @n_split_ops: number of entries in @split_ops, not that with split do/dump

 *	ops the number of entries is not the same as number of commands

 * @sock_priv_size: the size of per-socket private memory

 * @sock_priv_init: the per-socket private memory initializer

 * @sock_priv_destroy: the per-socket private memory destructor

 *

 * Attribute policies (the combination of @policy and @maxattr fields)

 * can be attached at the family level or at the operation level.
@@ -84,11 +87,17 @@ struct genl_family { 
	const struct genl_multicast_group *mcgrps;

	struct module		*module;



	size_t			sock_priv_size;

	void			(*sock_priv_init)(void *priv);

	void			(*sock_priv_destroy)(void *priv);



/* private: internal use only */

	/* protocol family identifier */

	int			id;

	/* starting number of multicast group IDs in this family */

	unsigned int		mcgrp_offset;

	/* list of per-socket privs */

	struct xarray		*sock_privs;

};



/**
@@ -298,6 +307,8 @@ static inline bool genl_info_is_ntf(const struct genl_info *info) 
	return !info->nlhdr;

}



void *__genl_sk_priv_get(struct genl_family *family, struct sock *sk);

void *genl_sk_priv_get(struct genl_family *family, struct sock *sk);

int genl_register_family(struct genl_family *family);

int genl_unregister_family(const struct genl_family *family);

void genl_notify(const struct genl_family *family, struct sk_buff *skb,

net/netlink/genetlink.c

+143 −1
Original line number Diff line number Diff line
@@ -631,6 +631,138 @@ static int genl_validate_ops(const struct genl_family *family) 
	return 0;

}



static void *genl_sk_priv_alloc(struct genl_family *family)

{

	void *priv;



	priv = kzalloc(family->sock_priv_size, GFP_KERNEL);

	if (!priv)

		return ERR_PTR(-ENOMEM);



	if (family->sock_priv_init)

		family->sock_priv_init(priv);



	return priv;

}



static void genl_sk_priv_free(const struct genl_family *family, void *priv)

{

	if (family->sock_priv_destroy)

		family->sock_priv_destroy(priv);

	kfree(priv);

}



static int genl_sk_privs_alloc(struct genl_family *family)

{

	if (!family->sock_priv_size)

		return 0;



	family->sock_privs = kzalloc(sizeof(*family->sock_privs), GFP_KERNEL);

	if (!family->sock_privs)

		return -ENOMEM;

	xa_init(family->sock_privs);

	return 0;

}



static void genl_sk_privs_free(const struct genl_family *family)

{

	unsigned long id;

	void *priv;



	if (!family->sock_priv_size)

		return;



	xa_for_each(family->sock_privs, id, priv)

		genl_sk_priv_free(family, priv);



	xa_destroy(family->sock_privs);

	kfree(family->sock_privs);

}



static void genl_sk_priv_free_by_sock(struct genl_family *family,

				      struct sock *sk)

{

	void *priv;



	if (!family->sock_priv_size)

		return;

	priv = xa_erase(family->sock_privs, (unsigned long) sk);

	if (!priv)

		return;

	genl_sk_priv_free(family, priv);

}



static void genl_release(struct sock *sk, unsigned long *groups)

{

	struct genl_family *family;

	unsigned int id;



	down_read(&cb_lock);



	idr_for_each_entry(&genl_fam_idr, family, id)

		genl_sk_priv_free_by_sock(family, sk);



	up_read(&cb_lock);

}



/**

 * __genl_sk_priv_get - Get family private pointer for socket, if exists

 *

 * @family: family

 * @sk: socket

 *

 * Lookup a private memory for a Generic netlink family and specified socket.

 *

 * Caller should make sure this is called in RCU read locked section.

 *

 * Return: valid pointer on success, otherwise negative error value

 * encoded by ERR_PTR(), NULL in case priv does not exist.

 */

void *__genl_sk_priv_get(struct genl_family *family, struct sock *sk)

{

	if (WARN_ON_ONCE(!family->sock_privs))

		return ERR_PTR(-EINVAL);

	return xa_load(family->sock_privs, (unsigned long) sk);

}



/**

 * genl_sk_priv_get - Get family private pointer for socket

 *

 * @family: family

 * @sk: socket

 *

 * Lookup a private memory for a Generic netlink family and specified socket.

 * Allocate the private memory in case it was not already done.

 *

 * Return: valid pointer on success, otherwise negative error value

 * encoded by ERR_PTR().

 */

void *genl_sk_priv_get(struct genl_family *family, struct sock *sk)

{

	void *priv, *old_priv;



	priv = __genl_sk_priv_get(family, sk);

	if (priv)

		return priv;



	/* priv for the family does not exist so far, create it. */



	priv = genl_sk_priv_alloc(family);

	if (IS_ERR(priv))

		return ERR_CAST(priv);



	old_priv = xa_cmpxchg(family->sock_privs, (unsigned long) sk, NULL,

			      priv, GFP_KERNEL);

	if (old_priv) {

		genl_sk_priv_free(family, priv);

		if (xa_is_err(old_priv))

			return ERR_PTR(xa_err(old_priv));

		/* Race happened, priv for the socket was already inserted. */

		return old_priv;

	}

	return priv;

}



/**

 * genl_register_family - register a generic netlink family

 * @family: generic netlink family
@@ -659,6 +791,10 @@ int genl_register_family(struct genl_family *family) 
		goto errout_locked;

	}



	err = genl_sk_privs_alloc(family);

	if (err)

		goto errout_locked;



	/*

	 * Sadly, a few cases need to be special-cased

	 * due to them having previously abused the API
@@ -679,7 +815,7 @@ int genl_register_family(struct genl_family *family) 
				      start, end + 1, GFP_KERNEL);

	if (family->id < 0) {

		err = family->id;

		goto errout_locked;

		goto errout_sk_privs_free;

	}



	err = genl_validate_assign_mc_groups(family);
@@ -698,6 +834,8 @@ int genl_register_family(struct genl_family *family) 


errout_remove:

	idr_remove(&genl_fam_idr, family->id);

errout_sk_privs_free:

	genl_sk_privs_free(family);

errout_locked:

	genl_unlock_all();

	return err;
@@ -728,6 +866,9 @@ int genl_unregister_family(const struct genl_family *family) 
	up_write(&cb_lock);

	wait_event(genl_sk_destructing_waitq,

		   atomic_read(&genl_sk_destructing_cnt) == 0);



	genl_sk_privs_free(family);



	genl_unlock();



	genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
@@ -1708,6 +1849,7 @@ static int __net_init genl_pernet_init(struct net *net) 
		.input		= genl_rcv,

		.flags		= NL_CFG_F_NONROOT_RECV,

		.bind		= genl_bind,

		.release	= genl_release,

	};



	/* we'll bump the group number right afterwards */