linux/net/netlink/policy.c

// SPDX-License-Identifier: GPL-2.0
/*
 * NETLINK      Policy advertisement to userspace
 *
 * 		Authors:	Johannes Berg <[email protected]>
 *
 * Copyright 2019 Intel Corporation
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <net/netlink.h>

#define INITIAL_POLICIES_ALLOC …

struct netlink_policy_dump_state { … };

static int add_policy(struct netlink_policy_dump_state **statep,
		      const struct nla_policy *policy,
		      unsigned int maxtype)
{ … }

/**
 * netlink_policy_dump_get_policy_idx - retrieve policy index
 * @state: the policy dump state
 * @policy: the policy to find
 * @maxtype: the policy's maxattr
 *
 * Returns: the index of the given policy in the dump state
 *
 * Call this to find a policy index when you've added multiple and e.g.
 * need to tell userspace which command has which policy (by index).
 *
 * Note: this will WARN and return 0 if the policy isn't found, which
 *	 means it wasn't added in the first place, which would be an
 *	 internal consistency bug.
 */
int netlink_policy_dump_get_policy_idx(struct netlink_policy_dump_state *state,
				       const struct nla_policy *policy,
				       unsigned int maxtype)
{ … }

static struct netlink_policy_dump_state *alloc_state(void)
{ … }

/**
 * netlink_policy_dump_add_policy - add a policy to the dump
 * @pstate: state to add to, may be reallocated, must be %NULL the first time
 * @policy: the new policy to add to the dump
 * @maxtype: the new policy's max attr type
 *
 * Returns: 0 on success, a negative error code otherwise.
 *
 * Call this to allocate a policy dump state, and to add policies to it. This
 * should be called from the dump start() callback.
 *
 * Note: on failures, any previously allocated state is freed.
 */
int netlink_policy_dump_add_policy(struct netlink_policy_dump_state **pstate,
				   const struct nla_policy *policy,
				   unsigned int maxtype)
{ … }

static bool
netlink_policy_dump_finished(struct netlink_policy_dump_state *state)
{ … }

/**
 * netlink_policy_dump_loop - dumping loop indicator
 * @state: the policy dump state
 *
 * Returns: %true if the dump continues, %false otherwise
 *
 * Note: this frees the dump state when finishing
 */
bool netlink_policy_dump_loop(struct netlink_policy_dump_state *state)
{ … }

int netlink_policy_dump_attr_size_estimate(const struct nla_policy *pt)
{ … }

static int
__netlink_policy_dump_write_attr(struct netlink_policy_dump_state *state,
				 struct sk_buff *skb,
				 const struct nla_policy *pt,
				 int nestattr)
{ … }

/**
 * netlink_policy_dump_write_attr - write a given attribute policy
 * @skb: the message skb to write to
 * @pt: the attribute's policy
 * @nestattr: the nested attribute ID to use
 *
 * Returns: 0 on success, an error code otherwise; -%ENODATA is
 *	    special, indicating that there's no policy data and
 *	    the attribute is generally rejected.
 */
int netlink_policy_dump_write_attr(struct sk_buff *skb,
				   const struct nla_policy *pt,
				   int nestattr)
{ … }

/**
 * netlink_policy_dump_write - write current policy dump attributes
 * @skb: the message skb to write to
 * @state: the policy dump state
 *
 * Returns: 0 on success, an error code otherwise
 */
int netlink_policy_dump_write(struct sk_buff *skb,
			      struct netlink_policy_dump_state *state)
{ … }

/**
 * netlink_policy_dump_free - free policy dump state
 * @state: the policy dump state to free
 *
 * Call this from the done() method to ensure dump state is freed.
 */
void netlink_policy_dump_free(struct netlink_policy_dump_state *state)
{ … }