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Commit ea697639 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

net: tcp: add RTAX_CC_ALGO fib handling 



This patch adds the minimum necessary for the RTAX_CC_ALGO congestion
control metric to be set up and dumped back to user space.

While the internal representation of RTAX_CC_ALGO is handled as a u32
key, we avoided to expose this implementation detail to user space, thus
instead, we chose the netlink attribute that is being exchanged between
user space to be the actual congestion control algorithm name, similarly
as in the setsockopt(2) API in order to allow for maximum flexibility,
even for 3rd party modules.

It is a bit unfortunate that RTAX_QUICKACK used up a whole RTAX slot as
it should have been stored in RTAX_FEATURES instead, we first thought
about reusing it for the congestion control key, but it brings more
complications and/or confusion than worth it.

Joint work with Florian Westphal.

Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c5c6a8ab

include/net/tcp.h

+7 −0
Original line number Diff line number Diff line
@@ -846,7 +846,14 @@ extern struct tcp_congestion_ops tcp_reno; 


struct tcp_congestion_ops *tcp_ca_find_key(u32 key);

u32 tcp_ca_get_key_by_name(const char *name);

#ifdef CONFIG_INET

char *tcp_ca_get_name_by_key(u32 key, char *buffer);

#else

static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)

{

	return NULL;

}

#endif



static inline bool tcp_ca_needs_ecn(const struct sock *sk)

{

include/uapi/linux/rtnetlink.h

+2 −0
Original line number Diff line number Diff line
@@ -389,6 +389,8 @@ enum { 
#define RTAX_INITRWND RTAX_INITRWND

	RTAX_QUICKACK,

#define RTAX_QUICKACK RTAX_QUICKACK

	RTAX_CC_ALGO,

#define RTAX_CC_ALGO RTAX_CC_ALGO

	__RTAX_MAX

};

net/core/rtnetlink.c

+13 −2
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ 
#include <net/arp.h>

#include <net/route.h>

#include <net/udp.h>

#include <net/tcp.h>

#include <net/sock.h>

#include <net/pkt_sched.h>

#include <net/fib_rules.h>
@@ -669,10 +670,20 @@ int rtnetlink_put_metrics(struct sk_buff *skb, u32 *metrics) 


	for (i = 0; i < RTAX_MAX; i++) {

		if (metrics[i]) {

			valid++;

			if (i == RTAX_CC_ALGO - 1) {

				char tmp[TCP_CA_NAME_MAX], *name;



				name = tcp_ca_get_name_by_key(metrics[i], tmp);

				if (!name)

					continue;

				if (nla_put_string(skb, i + 1, name))

					goto nla_put_failure;

			} else {

				if (nla_put_u32(skb, i + 1, metrics[i]))

					goto nla_put_failure;

			}

			valid++;

		}

	}



	if (!valid) {

net/decnet/dn_fib.c

+2 −1
Original line number Diff line number Diff line
@@ -298,7 +298,8 @@ struct dn_fib_info *dn_fib_create_info(const struct rtmsg *r, struct nlattr *att 
			int type = nla_type(attr);



			if (type) {

				if (type > RTAX_MAX || nla_len(attr) < 4)

				if (type > RTAX_MAX || type == RTAX_CC_ALGO ||

				    nla_len(attr) < 4)

					goto err_inval;



				fi->fib_metrics[type-1] = nla_get_u32(attr);

net/decnet/dn_table.c

+3 −1
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include <linux/route.h> /* RTF_xxx */

#include <net/neighbour.h>

#include <net/netlink.h>

#include <net/tcp.h>

#include <net/dst.h>

#include <net/flow.h>

#include <net/fib_rules.h>
@@ -273,7 +274,8 @@ static inline size_t dn_fib_nlmsg_size(struct dn_fib_info *fi) 
	size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))

			 + nla_total_size(4) /* RTA_TABLE */

			 + nla_total_size(2) /* RTA_DST */

			 + nla_total_size(4); /* RTA_PRIORITY */

			 + nla_total_size(4) /* RTA_PRIORITY */

			 + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */



	/* space for nested metrics */

	payload += nla_total_size((RTAX_MAX * nla_total_size(4)));