netlink: rework policy dump to support multiple policies (04a351a6) · Commits · 戴 / test

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 @@ send_attribute:
		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 @@ nla_put_failure:
		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);

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