Commit 04a351a6 authored by Johannes Berg's avatar Johannes Berg Committed by David S. Miller
Browse files

netlink: rework policy dump to support multiple policies 



Rework the policy dump code a bit to support adding multiple
policies to a single dump, in order to e.g. support per-op
policies in generic netlink.

v2:
 - move kernel-doc to implementation [Jakub]
 - squash the first patch to not flip-flop on the prototype
   [Jakub]
 - merge netlink_policy_dump_get_policy_idx() with the old
   get_policy_idx() we already had
 - rebase without Jakub's patch to have per-op dump

Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 899b07c5

include/net/netlink.h

+6 −3
Original line number Diff line number Diff line
@@ -1937,9 +1937,12 @@ void nla_get_range_signed(const struct nla_policy *pt, 


struct netlink_policy_dump_state;



int netlink_policy_dump_start(const struct nla_policy *policy,

			      unsigned int maxtype,

			      struct netlink_policy_dump_state **state);

int netlink_policy_dump_add_policy(struct netlink_policy_dump_state **pstate,

				   const struct nla_policy *policy,

				   unsigned int maxtype);

int netlink_policy_dump_get_policy_idx(struct netlink_policy_dump_state *state,

				       const struct nla_policy *policy,

				       unsigned int maxtype);

bool netlink_policy_dump_loop(struct netlink_policy_dump_state *state);

int netlink_policy_dump_write(struct sk_buff *skb,

			      struct netlink_policy_dump_state *state);

net/netlink/genetlink.c

+2 −1
Original line number Diff line number Diff line
@@ -1150,7 +1150,8 @@ static int ctrl_dumppolicy_start(struct netlink_callback *cb) 
	if (!rt->policy)

		return -ENODATA;



	return netlink_policy_dump_start(rt->policy, rt->maxattr, &ctx->state);

	return netlink_policy_dump_add_policy(&ctx->state, rt->policy,

					      rt->maxattr);

}



static int ctrl_dumppolicy(struct sk_buff *skb, struct netlink_callback *cb)

net/netlink/policy.c

+82 −20
Original line number Diff line number Diff line
@@ -63,44 +63,85 @@ static int add_policy(struct netlink_policy_dump_state **statep, 
	return 0;

}



static unsigned int get_policy_idx(struct netlink_policy_dump_state *state,

/**

 * 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)

{

	unsigned int i;



	if (WARN_ON(!policy || !maxtype))

                return 0;



	for (i = 0; i < state->n_alloc; i++) {

		if (state->policies[i].policy == policy &&

		    state->policies[i].maxtype == maxtype)

			return i;

	}



	WARN_ON_ONCE(1);

	return -1;

	WARN_ON(1);

	return 0;

}



int netlink_policy_dump_start(const struct nla_policy *policy,

			      unsigned int maxtype,

			      struct netlink_policy_dump_state **statep)

static struct netlink_policy_dump_state *alloc_state(void)

{

	struct netlink_policy_dump_state *state;



	state = kzalloc(struct_size(state, policies, INITIAL_POLICIES_ALLOC),

			GFP_KERNEL);

	if (!state)

		return ERR_PTR(-ENOMEM);

	state->n_alloc = INITIAL_POLICIES_ALLOC;



	return state;

}



/**

 * 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)

{

	struct netlink_policy_dump_state *state = *pstate;

	unsigned int policy_idx;

	int err;



	if (*statep)

		return 0;

	if (!state) {

		state = alloc_state();

		if (IS_ERR(state))

			return PTR_ERR(state);

	}



	/*

	 * walk the policies and nested ones first, and build

	 * a linear list of them.

	 */



	state = kzalloc(struct_size(state, policies, INITIAL_POLICIES_ALLOC),

			GFP_KERNEL);

	if (!state)

		return -ENOMEM;

	state->n_alloc = INITIAL_POLICIES_ALLOC;



	err = add_policy(&state, policy, maxtype);

	if (err)

		return err;
@@ -131,8 +172,7 @@ int netlink_policy_dump_start(const struct nla_policy *policy, 
		}

	}



	*statep = state;



	*pstate = state;

	return 0;

}
@@ -143,11 +183,26 @@ netlink_policy_dump_finished(struct netlink_policy_dump_state *state) 
	       !state->policies[state->policy_idx].policy;

}



/**

 * 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)

{

	return !netlink_policy_dump_finished(state);

}



/**

 * 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)

{
@@ -185,7 +240,8 @@ int netlink_policy_dump_write(struct sk_buff *skb, 
			type = NL_ATTR_TYPE_NESTED_ARRAY;

		if (pt->nested_policy && pt->len &&

		    (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_POLICY_IDX,

				 get_policy_idx(state, pt->nested_policy,

				 netlink_policy_dump_get_policy_idx(state,

								    pt->nested_policy,

								    pt->len)) ||

		     nla_put_u32(skb, NL_POLICY_TYPE_ATTR_POLICY_MAXTYPE,

				 pt->len)))
@@ -309,6 +365,12 @@ int netlink_policy_dump_write(struct sk_buff *skb, 
	return -ENOBUFS;

}



/**

 * 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)

{

	kfree(state);