lib/route/cls.c

/* SPDX-License-Identifier: LGPL-2.1-only */
/*
 * Copyright (c) 2003-2013 Thomas Graf <tgraf@suug.ch>
 */

/**
 * @ingroup tc
 * @defgroup cls Classifiers
 * @{
 */

#include "nl-default.h"

#include <linux/ethtool.h>

#include <netlink/netlink.h>
#include <netlink/utils.h>
#include <netlink/route/classifier.h>
#include <netlink/route/link.h>

#include "nl-route.h"
#include "tc-api.h"

/** @cond SKIP */
struct rtnl_cls {
	NL_TC_GENERIC(c);
	uint16_t c_prio;
	uint16_t c_protocol;
};

#define CLS_ATTR_PRIO		(TCA_ATTR_MAX << 1)
#define CLS_ATTR_PROTOCOL	(TCA_ATTR_MAX << 2)
/** @endcond */

static struct nl_object_ops cls_obj_ops;
static struct nl_cache_ops rtnl_cls_ops;


static int cls_build(struct rtnl_cls *cls, int type, int flags,
		     struct nl_msg **result)
{
	int err, prio, proto;
	struct tcmsg *tchdr;
	uint32_t required = TCA_ATTR_IFINDEX;

	if ((cls->ce_mask & required) != required) {
		APPBUG("ifindex must be specified");
		return -NLE_MISSING_ATTR;
	}

	err = rtnl_tc_msg_build(TC_CAST(cls), type, flags, result);
	if (err < 0)
		return err;

	tchdr = nlmsg_data(nlmsg_hdr(*result));
	prio = rtnl_cls_get_prio(cls);
	proto = rtnl_cls_get_protocol(cls);
	tchdr->tcm_info = TC_H_MAKE(prio << 16, htons(proto));

	return 0;
}

/**
 * @name Allocation/Freeing
 * @{
 */

struct rtnl_cls *rtnl_cls_alloc(void)
{
	struct rtnl_tc *tc;

	tc = TC_CAST(nl_object_alloc(&cls_obj_ops));
	if (tc)
		tc->tc_type = RTNL_TC_TYPE_CLS;

	return (struct rtnl_cls *) tc;
}

void rtnl_cls_put(struct rtnl_cls *cls)
{
	nl_object_put((struct nl_object *) cls);
}

/** @} */

/**
 * @name Attributes
 * @{
 */

void rtnl_cls_set_prio(struct rtnl_cls *cls, uint16_t prio)
{
	cls->c_prio = prio;
	cls->ce_mask |= CLS_ATTR_PRIO;
}

uint16_t rtnl_cls_get_prio(struct rtnl_cls *cls)
{
	if (cls->ce_mask & CLS_ATTR_PRIO)
		return cls->c_prio;
	else
		return 0;
}

void rtnl_cls_set_protocol(struct rtnl_cls *cls, uint16_t protocol)
{
	cls->c_protocol = protocol;
	cls->ce_mask |= CLS_ATTR_PROTOCOL;
}

uint16_t rtnl_cls_get_protocol(struct rtnl_cls *cls)
{
	if (cls->ce_mask & CLS_ATTR_PROTOCOL)
		return cls->c_protocol;
	else
		return ETH_P_ALL;
}

/** @} */


/**
 * @name Addition/Modification/Deletion
 * @{
 */

/**
 * Build a netlink message requesting the addition of a classifier
 * @arg cls		Classifier to add 
 * @arg flags		Additional netlink message flags
 * @arg result		Pointer to store resulting netlink message
 *
 * The behaviour of this function is identical to rtnl_cls_add() with
 * the exception that it will not send the message but return it int the
 * provided return pointer instead.
 *
 * @see rtnl_cls_add()
 *
 * @return 0 on success or a negative error code.
 */
int rtnl_cls_build_add_request(struct rtnl_cls *cls, int flags,
			       struct nl_msg **result)
{
	if (!(flags & NLM_F_CREATE) && !(cls->ce_mask & CLS_ATTR_PRIO)) {
		APPBUG("prio must be specified if not a new classifier");
		return -NLE_MISSING_ATTR;
	}

	return cls_build(cls, RTM_NEWTFILTER, flags, result);
}

/**
 * Add/Update classifier
 * @arg sk		Netlink socket
 * @arg cls		Classifier to add/update
 * @arg flags		Additional netlink message flags
 *
 * Builds a \c RTM_NEWTFILTER netlink message requesting the addition
 * of a new classifier and sends the message to the kernel. The
 * configuration of the classifier is derived from the attributes of
 * the specified traffic class.
 *
 * The following flags may be specified:
 *  - \c NLM_F_CREATE:  Create classifier if it does not exist,
 *                      otherwise -NLE_OBJ_NOTFOUND is returned.
 *  - \c NLM_F_EXCL:    Return -NLE_EXISTS if a classifier with
 *                      matching handle exists already.
 *
 * Existing classifiers with matching handles will be updated, unless
 * the flag \c NLM_F_EXCL is specified. If no matching classifier
 * exists, it will be created if the flag \c NLM_F_CREATE is set,
 * otherwise the error -NLE_OBJ_NOTFOUND is returned. 
 *
 * If the parent qdisc does not support classes, the error
 * \c NLE_OPNOTSUPP is returned.
 *
 * After sending, the function will wait for the ACK or an eventual
 * error message to be received and will therefore block until the
 * operation has been completed.
 *
 * @note Disabling auto-ack (nl_socket_disable_auto_ack()) will cause
 *       this function to return immediately after sending. In this case,
 *       it is the responsibility of the caller to handle any error
 *       messages returned.
 *
 * @return 0 on success or a negative error code.
 */
int rtnl_cls_add(struct nl_sock *sk, struct rtnl_cls *cls, int flags)
{
	struct nl_msg *msg;
	int err;
	
	if ((err = rtnl_cls_build_add_request(cls, flags, &msg)) < 0)
		return err;

	return nl_send_sync(sk, msg);
}

/**
 * Build a netlink message to change classifier attributes
 * @arg cls		classifier to change
 * @arg flags		additional netlink message flags
 * @arg result		Pointer to store resulting message.
 *
 * Builds a new netlink message requesting a change of a neigh
 * attributes. The netlink message header isn't fully equipped with
 * all relevant fields and must thus be sent out via nl_send_auto_complete()
 * or supplemented as needed.
 *
 * @return 0 on success or a negative error code.
 */
int rtnl_cls_build_change_request(struct rtnl_cls *cls, int flags,
				  struct nl_msg **result)
{
	return cls_build(cls, RTM_NEWTFILTER, NLM_F_REPLACE | flags, result);
}

/**
 * Change a classifier
 * @arg sk		Netlink socket.
 * @arg cls		classifier to change
 * @arg flags		additional netlink message flags
 *
 * Builds a netlink message by calling rtnl_cls_build_change_request(),
 * sends the request to the kernel and waits for the next ACK to be
 * received and thus blocks until the request has been processed.
 *
 * @return 0 on success or a negative error if an error occured.
 */
int rtnl_cls_change(struct nl_sock *sk, struct rtnl_cls *cls, int flags)
{
	struct nl_msg *msg;
	int err;
	
	if ((err = rtnl_cls_build_change_request(cls, flags, &msg)) < 0)
		return err;
	
	return nl_send_sync(sk, msg);
}

/**
 * Build netlink message requesting the deletion of a classifier
 * @arg cls		Classifier to delete
 * @arg flags		Additional netlink message flags
 * @arg result		Pointer to store resulting netlink message
 *
 * The behaviour of this function is identical to rtnl_cls_delete() with
 * the exception that it will not send the message but return it in the
 * provided return pointer instead.
 *
 * @see rtnl_cls_delete()
 *
 * @return 0 on success or a negative error code.
 */
int rtnl_cls_build_delete_request(struct rtnl_cls *cls, int flags,
				  struct nl_msg **result)
{
	uint32_t required = CLS_ATTR_PRIO;

	if ((cls->ce_mask & required) != required) {
		APPBUG("prio must be specified");
		return -NLE_MISSING_ATTR;
	}

	return cls_build(cls, RTM_DELTFILTER, flags, result);
}

/**
 * Delete classifier
 * @arg sk		Netlink socket
 * @arg cls		Classifier to delete
 * @arg flags		Additional netlink message flags
 *
 * Builds a \c RTM_DELTFILTER netlink message requesting the deletion
 * of a classifier and sends the message to the kernel.
 *
 * The message is constructed out of the following attributes:
 * - \c ifindex (required)
 * - \c prio (required)
 * - \c protocol (required)
 * - \c handle (required)
 * - \c parent (optional, if not specified parent equals root-qdisc)
 * - \c kind (optional, must match if provided)
 *
 * All other classifier attributes including all class type specific
 * attributes are ignored.
 *
 * After sending, the function will wait for the ACK or an eventual
 * error message to be received and will therefore block until the
 * operation has been completed.
 *
 * @note Disabling auto-ack (nl_socket_disable_auto_ack()) will cause
 *       this function to return immediately after sending. In this case,
 *       it is the responsibility of the caller to handle any error
 *       messages returned.
 *
 * @return 0 on success or a negative error code.
 */
int rtnl_cls_delete(struct nl_sock *sk, struct rtnl_cls *cls, int flags)
{
	struct nl_msg *msg;
	int err;
	
	if ((err = rtnl_cls_build_delete_request(cls, flags, &msg)) < 0)
		return err;
	
	return nl_send_sync(sk, msg);
}

/** @} */

/**
 * @name Cache Related Functions
 * @{
 */

/**
 * Allocate a cache and fill it with all configured classifiers
 * @arg sk		Netlink socket
 * @arg ifindex		Interface index of the network device
 * @arg parent		Parent qdisc/traffic class class
 * @arg result		Pointer to store the created cache
 *
 * Allocates a new classifier cache and fills it with a list of all
 * configured classifier attached to the specified parent qdisc/traffic
 * class on the specified network device. Release the cache with
 * nl_cache_free().
 *
 * @return 0 on success or a negative error code.
 */
int rtnl_cls_alloc_cache(struct nl_sock *sk, int ifindex, uint32_t parent,
			 struct nl_cache **result)
{
	struct nl_cache * cache;
	int err;
	
	if (!(cache = nl_cache_alloc(&rtnl_cls_ops)))
		return -NLE_NOMEM;

	cache->c_iarg1 = ifindex;
	cache->c_iarg2 = parent;
	
	if (sk && (err = nl_cache_refill(sk, cache)) < 0) {
		nl_cache_free(cache);
		return err;
	}

	*result = cache;
	return 0;
}

/**
 * Set interface index and parent handle for classifier cache.
 * @arg cache 		Pointer to cache
 * @arg parent 		Parent qdisc/traffic class class
 *
 * Set the interface index and parent handle of a classifier cache.
 * This is useful for reusing some existed classifier cache to reduce
 * the overhead introduced by memory allocation.
 *
 * @return void.
 */
void rtnl_cls_cache_set_tc_params(struct nl_cache *cache,
				  int ifindex, uint32_t parent)
{
	cache->c_iarg1 = ifindex;
	cache->c_iarg2 = parent;
}

/**
 * Search classifier by interface index, parent and handle
 * @arg cache           Classifier cache
 * @arg ifindex         Interface index
 * @arg parent          Parent
 * @arg handle          Handle
 *
 * Searches a classifier cache previously allocated with rtnl_cls_alloc_cache()
 * and searches for a classifier matching the interface index, parent
 * and handle.
 *
 * The reference counter is incremented before returning the classifier,
 * therefore the reference must be given back with rtnl_cls_put() after usage.
 *
 * @return Classifier or NULL if no match was found.
 */
struct rtnl_cls *rtnl_cls_find_by_handle(struct nl_cache *cache, int ifindex, uint32_t parent,
                                         uint32_t handle)
{
	struct rtnl_cls *cls;

	if (cache->c_ops != &rtnl_cls_ops)
		return NULL;

	nl_list_for_each_entry(cls, &cache->c_items, ce_list) {
		if ((cls->c_parent == parent) &&
		    cls->c_ifindex == ((unsigned)ifindex) &&
		    (cls->c_handle == handle)) {
			nl_object_get((struct nl_object *) cls);
			return cls;
		}
	}

	return NULL;
}

/**
 * Search classifier by interface index, parent and priority
 * @arg cache           Classifier cache
 * @arg ifindex         Interface index
 * @arg parent          Parent
 * @arg prio            Priority
 *
 * Searches a classifier cache previously allocated with rtnl_cls_alloc_cache()
 * and searches for a classifier matching the interface index, parent
 * and prio.
 *
 * The reference counter is incremented before returning the classifier,
 * therefore the reference must be given back with rtnl_cls_put() after usage.
 *
 * @return Classifier or NULL if no match was found.
 */
struct rtnl_cls *rtnl_cls_find_by_prio(struct nl_cache *cache, int ifindex,
                                       uint32_t parent, uint16_t prio)
{
	struct rtnl_cls *cls;

	if (cache->c_ops != &rtnl_cls_ops)
		return NULL;

	nl_list_for_each_entry(cls, &cache->c_items, ce_list) {
		if ((cls->c_parent == parent) &&
		    cls->c_ifindex == ((unsigned)ifindex) &&
		    (cls->c_prio == prio)) {
			nl_object_get((struct nl_object *)cls);
			return cls;
		}
	}

	return NULL;
}

/** @} */

static void cls_dump_line(struct rtnl_tc *tc, struct nl_dump_params *p)
{
	struct rtnl_cls *cls = (struct rtnl_cls *) tc;
	char buf[32];

	nl_dump(p, " prio %u protocol %s", cls->c_prio,
		nl_ether_proto2str(cls->c_protocol, buf, sizeof(buf)));
}

static int cls_msg_parser(struct nl_cache_ops *ops, struct sockaddr_nl *who,
			  struct nlmsghdr *nlh, struct nl_parser_param *pp)
{
	struct rtnl_cls *cls;
	int err;

	if (!(cls = rtnl_cls_alloc()))
		return -NLE_NOMEM;

	if ((err = rtnl_tc_msg_parse(nlh, TC_CAST(cls))) < 0)
		goto errout;

	cls->c_prio = TC_H_MAJ(cls->c_info) >> 16;
	if (cls->c_prio)
		cls->ce_mask |= CLS_ATTR_PRIO;
	cls->c_protocol = ntohs(TC_H_MIN(cls->c_info));
	if (cls->c_protocol)
		cls->ce_mask |= CLS_ATTR_PROTOCOL;

	err = pp->pp_cb(OBJ_CAST(cls), pp);
errout:
	rtnl_cls_put(cls);

	return err;
}

static int cls_request_update(struct nl_cache *cache, struct nl_sock *sk)
{
	struct tcmsg tchdr = {
		.tcm_family = AF_UNSPEC,
		.tcm_ifindex = cache->c_iarg1,
		.tcm_parent = cache->c_iarg2,
	};

	return nl_send_simple(sk, RTM_GETTFILTER, NLM_F_DUMP, &tchdr,
			      sizeof(tchdr));
}

static struct rtnl_tc_type_ops cls_ops = {
	.tt_type		= RTNL_TC_TYPE_CLS,
	.tt_dump_prefix		= "cls",
	.tt_dump = {
		[NL_DUMP_LINE]	= cls_dump_line,
	},
};

static struct nl_cache_ops rtnl_cls_ops = {
	.co_name		= "route/cls",
	.co_hdrsize		= sizeof(struct tcmsg),
	.co_msgtypes		= {
					{ RTM_NEWTFILTER, NL_ACT_NEW, "new" },
					{ RTM_DELTFILTER, NL_ACT_DEL, "del" },
					{ RTM_GETTFILTER, NL_ACT_GET, "get" },
					END_OF_MSGTYPES_LIST,
				  },
	.co_protocol		= NETLINK_ROUTE,
	.co_groups		= tc_groups,
	.co_request_update	= cls_request_update,
	.co_msg_parser		= cls_msg_parser,
	.co_obj_ops		= &cls_obj_ops,
};

static struct nl_object_ops cls_obj_ops = {
	.oo_name		= "route/cls",
	.oo_size		= sizeof(struct rtnl_cls),
	.oo_free_data		= rtnl_tc_free_data,
	.oo_clone		= rtnl_tc_clone,
	.oo_dump = {
	    [NL_DUMP_LINE]	= rtnl_tc_dump_line,
	    [NL_DUMP_DETAILS]	= rtnl_tc_dump_details,
	    [NL_DUMP_STATS]	= rtnl_tc_dump_stats,
	},
	.oo_compare		= rtnl_tc_compare,
	.oo_id_attrs		= (TCA_ATTR_IFINDEX | TCA_ATTR_HANDLE),
};

static void _nl_init cls_init(void)
{
	rtnl_tc_type_register(&cls_ops);
	nl_cache_mngt_register(&rtnl_cls_ops);
}

static void _nl_exit cls_exit(void)
{
	nl_cache_mngt_unregister(&rtnl_cls_ops);
	rtnl_tc_type_unregister(&cls_ops);
}

/** @} */