network: introduce TrafficControl

Add network delay to a interface

man/systemd.network.xml

@@ -2287,6 +2287,56 @@
       </variablelist>
   </refsect1>
 
+  <refsect1>
+    <title>[TrafficControlQueueingDiscipline] Section Options</title>
+    <para>The <literal>[TrafficControlQueueingDiscipline]</literal> section manages the Traffic control. It can be used
+    to configure the kernel packet scheduler and simulate packet delay and loss for UDP or TCP applications,
+    or limit the bandwidth usage of a particular service to simulate internet connections.</para>
+
+    <variablelist class='network-directives'>
+      <varlistentry>
+        <term><varname>Parent=</varname></term>
+        <listitem>
+          <para>Specifies the parent Queueing Discipline (qdisc). Takes one of <literal>root</literal>
+          or <literal>clsact</literal>. Defaults to <literal>root</literal>.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>NetworkEmulatorDelaySec=</varname></term>
+        <listitem>
+          <para>Specifies the fixed amount of delay to be added to all packets going out of the
+          interface. Defaults to unset.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>NetworkEmulatorDelayJitterSec=</varname></term>
+        <listitem>
+          <para>Specifies the chosen delay to be added to the packets outgoing to the network
+          interface. Defaults to unset.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>NetworkEmulatorPacketLimit=</varname></term>
+        <listitem>
+          <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
+          An unsigned integer ranges 0 to 4294967294. Defaults to 1000.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>NetworkEmulatorLossRate=</varname></term>
+        <listitem>
+          <para>Specifies an independent loss probability to be added to the packets outgoing from the
+          network interface. Takes a percentage value, suffixed with "%". Defaults to unset.</para>
+        </listitem>
+      </varlistentry>
+
+    </variablelist>
+  </refsect1>
+
   <refsect1>
     <title>[BridgeVLAN] Section Options</title>
       <para>The <literal>[BridgeVLAN]</literal> section manages the VLAN ID configuration of a bridge port and accepts

src/libsystemd/sd-netlink/netlink-types.c

@@ -18,9 +18,10 @@
 #include <linux/if_link.h>
 #include <linux/if_macsec.h>
 #include <linux/if_tunnel.h>
-#include <linux/nexthop.h>
 #include <linux/l2tp.h>
+#include <linux/nexthop.h>
 #include <linux/nl80211.h>
+#include <linux/pkt_sched.h>
 #include <linux/veth.h>
 #include <linux/wireguard.h>
 
@@ -733,6 +734,18 @@ static const NLTypeSystem rtnl_nexthop_type_system = {
        .types = rtnl_nexthop_types,
 };
 
+static const NLType rtnl_qdisc_types[] = {
+        [TCA_KIND]           = { .type = NETLINK_TYPE_STRING },
+        [TCA_OPTIONS]        = { .size = sizeof(struct tc_netem_qopt) },
+        [TCA_INGRESS_BLOCK]  = { .type = NETLINK_TYPE_U32 },
+        [TCA_EGRESS_BLOCK]   = { .type = NETLINK_TYPE_U32 },
+};
+
+static const NLTypeSystem rtnl_qdisc_type_system = {
+        .count = ELEMENTSOF(rtnl_qdisc_types),
+        .types = rtnl_qdisc_types,
+};
+
 static const NLType rtnl_types[] = {
         [NLMSG_DONE]       = { .type = NETLINK_TYPE_NESTED, .type_system = &empty_type_system, .size = 0 },
         [NLMSG_ERROR]      = { .type = NETLINK_TYPE_NESTED, .type_system = &empty_type_system, .size = sizeof(struct nlmsgerr) },
@@ -758,6 +771,9 @@ static const NLType rtnl_types[] = {
         [RTM_NEWNEXTHOP]   = { .type = NETLINK_TYPE_NESTED, .type_system = &rtnl_nexthop_type_system, .size = sizeof(struct nhmsg) },
         [RTM_DELNEXTHOP]   = { .type = NETLINK_TYPE_NESTED, .type_system = &rtnl_nexthop_type_system, .size = sizeof(struct nhmsg) },
         [RTM_GETNEXTHOP]   = { .type = NETLINK_TYPE_NESTED, .type_system = &rtnl_nexthop_type_system, .size = sizeof(struct nhmsg) },
+        [RTM_NEWQDISC]     = { .type = NETLINK_TYPE_NESTED, .type_system = &rtnl_qdisc_type_system, .size = sizeof(struct tcmsg) },
+        [RTM_DELQDISC]     = { .type = NETLINK_TYPE_NESTED, .type_system = &rtnl_qdisc_type_system, .size = sizeof(struct tcmsg) },
+        [RTM_GETQDISC]     = { .type = NETLINK_TYPE_NESTED, .type_system = &rtnl_qdisc_type_system, .size = sizeof(struct tcmsg) },
 };
 
 const NLTypeSystem rtnl_type_system_root = {

src/libsystemd/sd-netlink/netlink-util.h

@@ -41,6 +41,10 @@ static inline bool rtnl_message_type_is_routing_policy_rule(uint16_t type) {
         return IN_SET(type, RTM_NEWRULE, RTM_DELRULE, RTM_GETRULE);
 }
 
+static inline bool rtnl_message_type_is_qdisc(uint16_t type) {
+        return IN_SET(type, RTM_NEWQDISC, RTM_DELQDISC, RTM_GETQDISC);
+}
+
 int rtnl_set_link_name(sd_netlink **rtnl, int ifindex, const char *name);
 int rtnl_set_link_properties(sd_netlink **rtnl, int ifindex, const char *alias, const struct ether_addr *mac, uint32_t mtu);
 

src/libsystemd/sd-netlink/rtnl-message.c

@@ -1033,3 +1033,46 @@ int sd_rtnl_message_routing_policy_rule_get_rtm_src_prefixlen(const sd_netlink_m
 
         return 0;
 }
+
+int sd_rtnl_message_new_qdisc(sd_netlink *rtnl, sd_netlink_message **ret, uint16_t nlmsg_type, int tcm_family, int tcm_ifindex) {
+        struct tcmsg *tcm;
+        int r;
+
+        assert_return(rtnl_message_type_is_qdisc(nlmsg_type), -EINVAL);
+        assert_return(ret, -EINVAL);
+
+        r = message_new(rtnl, ret, nlmsg_type);
+        if (r < 0)
+                return r;
+
+        if (nlmsg_type == RTM_NEWQDISC)
+                (*ret)->hdr->nlmsg_flags |= NLM_F_CREATE | NLM_F_EXCL;
+
+        tcm = NLMSG_DATA((*ret)->hdr);
+        tcm->tcm_family = tcm_family;
+        tcm->tcm_ifindex = tcm_ifindex;
+
+        return 0;
+}
+
+int sd_rtnl_message_set_qdisc_parent(sd_netlink_message *m, uint32_t parent) {
+        struct tcmsg *tcm;
+
+        assert_return(rtnl_message_type_is_qdisc(m->hdr->nlmsg_type), -EINVAL);
+
+        tcm = NLMSG_DATA(m->hdr);
+        tcm->tcm_parent = parent;
+
+        return 0;
+}
+
+int sd_rtnl_message_set_qdisc_handle(sd_netlink_message *m, uint32_t handle) {
+        struct tcmsg *tcm;
+
+        assert_return(rtnl_message_type_is_qdisc(m->hdr->nlmsg_type), -EINVAL);
+
+        tcm = NLMSG_DATA(m->hdr);
+        tcm->tcm_handle = handle;
+
+        return 0;
+}

src/network/meson.build

@@ -105,6 +105,12 @@ sources = files('''
         networkd-util.h
         networkd-wifi.c
         networkd-wifi.h
+        tc/netem.c
+        tc/netem.h
+        tc/qdisc.c
+        tc/qdisc.h
+        tc/tc-util.c
+        tc/tc-util.h
 '''.split())
 
 systemd_networkd_sources = files('networkd.c')

src/network/networkd-link.c

@@ -43,6 +43,7 @@
 #include "tmpfile-util.h"
 #include "udev-util.h"
 #include "util.h"
+#include "tc/qdisc.h"
 #include "virt.h"
 
 uint32_t link_get_vrf_table(Link *link) {
@@ -2581,6 +2582,8 @@ static int link_drop_config(Link *link) {
 }
 
 static int link_configure(Link *link) {
+        QDiscs *qdisc;
+        Iterator i;
         int r;
 
         assert(link);
@@ -2590,6 +2593,9 @@ static int link_configure(Link *link) {
         if (link->iftype == ARPHRD_CAN)
                 return link_configure_can(link);
 
+        ORDERED_HASHMAP_FOREACH(qdisc, link->network->qdiscs_by_section, i)
+                (void) qdisc_configure(link, qdisc);
+
         /* Drop foreign config, but ignore loopback or critical devices.
          * We do not want to remove loopback address or addresses used for root NFS. */
         if (!(link->flags & IFF_LOOPBACK) &&

src/network/networkd-link.h

@@ -78,6 +78,7 @@ typedef struct Link {
         unsigned nexthop_messages;
         unsigned routing_policy_rule_messages;
         unsigned routing_policy_rule_remove_messages;
+        unsigned qdisc_messages;
         unsigned enslaving;
 
         Set *addresses;

src/network/networkd-network-gperf.gperf

@@ -13,6 +13,8 @@ _Pragma("GCC diagnostic ignored \"-Wimplicit-fallthrough\"")
 #include "networkd-ndisc.h"
 #include "networkd-network.h"
 #include "vlan-util.h"
+#include "tc/qdisc.h"
+#include "tc/netem.h"
 %}
 struct ConfigPerfItem;
 %null_strings
@@ -241,6 +243,11 @@ CAN.BitRate,                            config_parse_si_size,
 CAN.SamplePoint,                        config_parse_permille,                           0,                             offsetof(Network, can_sample_point)
 CAN.RestartSec,                         config_parse_sec,                                0,                             offsetof(Network, can_restart_us)
 CAN.TripleSampling,                     config_parse_tristate,                           0,                             offsetof(Network, can_triple_sampling)
+TrafficControlQueueingDiscipline.Parent,                             config_parse_tc_qdiscs_parent,                     0,                             0
+TrafficControlQueueingDiscipline.NetworkEmulatorDelaySec,            config_parse_tc_network_emulator_delay,            0,                             0
+TrafficControlQueueingDiscipline.NetworkEmulatorDelayJitterSec,      config_parse_tc_network_emulator_delay,            0,                             0
+TrafficControlQueueingDiscipline.NetworkEmulatorLossRate,            config_parse_tc_network_emulator_loss_rate,        0,                             0
+TrafficControlQueueingDiscipline.NetworkEmulatorPacketLimit,         config_parse_tc_network_emulator_packet_limit,     0,                             0
 /* backwards compatibility: do not add new entries to this section */
 Network.IPv4LL,                         config_parse_ipv4ll,                             0,                             offsetof(Network, link_local)
 DHCP.ClientIdentifier,                  config_parse_dhcp_client_identifier,             0,                             offsetof(Network, dhcp_client_identifier)

src/network/networkd-network.c

@@ -471,6 +471,7 @@ int network_load_one(Manager *manager, OrderedHashmap **networks, const char *fi
                               "IPv6PrefixDelegation\0"
                               "IPv6Prefix\0"
                               "IPv6RoutePrefix\0"
+                              "TrafficControlQueueingDiscipline\0"
                               "CAN\0",
                               config_item_perf_lookup, network_network_gperf_lookup,
                               CONFIG_PARSE_WARN, network);
@@ -663,6 +664,7 @@ static Network *network_free(Network *network) {
         hashmap_free(network->address_labels_by_section);
         hashmap_free(network->prefixes_by_section);
         hashmap_free(network->rules_by_section);
+        ordered_hashmap_free_with_destructor(network->qdiscs_by_section, qdisc_free);
 
         if (network->manager &&
             network->manager->duids_requesting_uuid)

src/network/networkd-network.h

@@ -28,6 +28,7 @@
 #include "networkd-util.h"
 #include "ordered-set.h"
 #include "resolve-util.h"
+#include "tc/qdisc.h"
 
 typedef enum IPv6PrivacyExtensions {
         /* The values map to the kernel's /proc/sys/net/ipv6/conf/xxx/use_tempaddr values */
@@ -265,6 +266,7 @@ struct Network {
         Hashmap *prefixes_by_section;
         Hashmap *route_prefixes_by_section;
         Hashmap *rules_by_section;
+        OrderedHashmap *qdiscs_by_section;
 
         /* All kinds of DNS configuration */
         struct in_addr_data *dns;

src/network/tc/netem.c

@@ -0,0 +1,213 @@
+/* SPDX-License-Identifier: LGPL-2.1+
+ * Copyright © 2019 VMware, Inc. */
+
+#include <linux/pkt_sched.h>
+#include <math.h>
+
+#include "alloc-util.h"
+#include "conf-parser.h"
+#include "hashmap.h"
+#include "in-addr-util.h"
+#include "netem.h"
+#include "netlink-util.h"
+#include "networkd-manager.h"
+#include "parse-util.h"
+#include "qdisc.h"
+#include "string-util.h"
+#include "tc-util.h"
+#include "util.h"
+
+int network_emulator_new(NetworkEmulator **ret) {
+        NetworkEmulator *ne = NULL;
+
+        ne = new(NetworkEmulator, 1);
+        if (!ne)
+                return -ENOMEM;
+
+        *ne = (NetworkEmulator) {
+                .delay = USEC_INFINITY,
+                .jitter = USEC_INFINITY,
+        };
+
+        *ret = TAKE_PTR(ne);
+
+        return 0;
+}
+
+int network_emulator_fill_message(Link *link, QDiscs *qdisc, sd_netlink_message *req) {
+        struct tc_netem_qopt opt = {
+               .limit = 1000,
+        };
+        int r;
+
+        assert(link);
+        assert(qdisc);
+        assert(req);
+
+        if (qdisc->ne.limit > 0)
+                opt.limit = qdisc->ne.limit;
+
+        if (qdisc->ne.loss > 0)
+                opt.loss = qdisc->ne.loss;
+
+        if (qdisc->ne.delay != USEC_INFINITY) {
+                r = tc_time_to_tick(qdisc->ne.delay, &opt.latency);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "Failed to calculate latency in TCA_OPTION: %m");
+        }
+
+        if (qdisc->ne.jitter != USEC_INFINITY) {
+                r = tc_time_to_tick(qdisc->ne.jitter, &opt.jitter);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "Failed to calculate jitter in TCA_OPTION: %m");
+        }
+
+        r = sd_netlink_message_append_data(req, TCA_OPTIONS, &opt, sizeof(struct tc_netem_qopt));
+        if (r < 0)
+                return log_link_error_errno(link, r, "Could not append TCA_OPTION attribute: %m");
+
+        return 0;
+}
+
+int config_parse_tc_network_emulator_delay(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        _cleanup_(qdisc_free_or_set_invalidp) QDiscs *qdisc = NULL;
+        Network *network = data;
+        usec_t u;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+        assert(data);
+
+        r = qdisc_new_static(network, filename, section_line, &qdisc);
+        if (r < 0)
+                return r;
+
+        if (isempty(rvalue)) {
+                if (streq(lvalue, "NetworkEmulatorDelaySec"))
+                        qdisc->ne.delay = USEC_INFINITY;
+                else if (streq(lvalue, "NetworkEmulatorDelayJitterSec"))
+                        qdisc->ne.jitter = USEC_INFINITY;
+
+                qdisc = NULL;
+                return 0;
+        }
+
+        r = parse_sec(rvalue, &u);
+        if (r < 0) {
+                log_syntax(unit, LOG_ERR, filename, line, r,
+                           "Failed to parse '%s=', ignoring assignment: %s",
+                           lvalue, rvalue);
+                return 0;
+        }
+
+        if (streq(lvalue, "NetworkEmulatorDelaySec"))
+                qdisc->ne.delay = u;
+        else if (streq(lvalue, "NetworkEmulatorDelayJitterSec"))
+                qdisc->ne.jitter = u;
+
+        qdisc->has_network_emulator = true;
+        qdisc = NULL;
+
+        return 0;
+}
+
+int config_parse_tc_network_emulator_loss_rate(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        _cleanup_(qdisc_free_or_set_invalidp) QDiscs *qdisc = NULL;
+        Network *network = data;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+        assert(data);
+
+        r = qdisc_new_static(network, filename, section_line, &qdisc);
+        if (r < 0)
+                return r;
+
+        if (isempty(rvalue)) {
+                qdisc->ne.loss = 0;
+
+                qdisc = NULL;
+                return 0;
+        }
+
+        r = parse_tc_percent(rvalue, &qdisc->ne.loss);
+        if (r < 0) {
+                log_syntax(unit, LOG_ERR, filename, line, r,
+                           "Failed to parse 'NetworkEmularorLossRate=', ignoring assignment: %s",
+                           rvalue);
+                return 0;
+        }
+
+        qdisc = NULL;
+        return 0;
+}
+
+int config_parse_tc_network_emulator_packet_limit(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        _cleanup_(qdisc_free_or_set_invalidp) QDiscs *qdisc = NULL;
+        Network *network = data;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+        assert(data);
+
+        r = qdisc_new_static(network, filename, section_line, &qdisc);
+        if (r < 0)
+                return r;
+
+        if (isempty(rvalue)) {
+                qdisc->ne.limit = 0;
+                qdisc = NULL;
+
+                return 0;
+        }
+
+        r = safe_atou(rvalue, &qdisc->ne.limit);
+        if (r < 0) {
+                log_syntax(unit, LOG_ERR, filename, line, r,
+                           "Failed to parse 'NetworkEmulatorPacketLimit=', ignoring assignment: %s",
+                           rvalue);
+                return 0;
+        }
+
+        qdisc = NULL;
+        return 0;
+}

src/network/tc/netem.h

@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: LGPL-2.1+
+ * Copyright © 2019 VMware, Inc. */
+#pragma once
+
+#include "sd-netlink.h"
+
+#include "conf-parser.h"
+#include "macro.h"
+#include "../networkd-link.h"
+#include "time-util.h"
+
+typedef struct NetworkEmulator NetworkEmulator;
+typedef struct QDiscs QDiscs;
+
+struct NetworkEmulator {
+        usec_t delay;
+        usec_t jitter;
+
+        uint32_t limit;
+        uint32_t loss;
+};
+
+int network_emulator_new(NetworkEmulator **ret);
+int network_emulator_fill_message(Link *link, QDiscs *qdisc, sd_netlink_message *req);
+
+CONFIG_PARSER_PROTOTYPE(config_parse_tc_network_emulator_delay);
+CONFIG_PARSER_PROTOTYPE(config_parse_tc_network_emulator_loss_rate);
+CONFIG_PARSER_PROTOTYPE(config_parse_tc_network_emulator_packet_limit);

src/network/tc/qdisc.c

@@ -0,0 +1,196 @@
+/* SPDX-License-Identifier: LGPL-2.1+
+ * Copyright © 2019 VMware, Inc. */
+
+#include <linux/pkt_sched.h>
+
+#include "alloc-util.h"
+#include "conf-parser.h"
+#include "in-addr-util.h"
+#include "netlink-util.h"
+#include "networkd-manager.h"
+#include "parse-util.h"
+#include "qdisc.h"
+#include "set.h"
+#include "string-util.h"
+#include "util.h"
+
+static int qdisc_new(QDiscs **ret) {
+        QDiscs *qdisc;
+
+        qdisc = new(QDiscs, 1);
+        if (!qdisc)
+                return -ENOMEM;
+
+        *qdisc = (QDiscs) {
+                .family = AF_UNSPEC,
+                .parent = TC_H_ROOT,
+        };
+
+        *ret = TAKE_PTR(qdisc);
+
+        return 0;
+}
+
+int qdisc_new_static(Network *network, const char *filename, unsigned section_line, QDiscs **ret) {
+        _cleanup_(network_config_section_freep) NetworkConfigSection *n = NULL;
+        _cleanup_(qdisc_freep) QDiscs *qdisc = NULL;
+        int r;
+
+        assert(network);
+        assert(ret);
+        assert(!!filename == (section_line > 0));
+
+        if (filename) {
+                r = network_config_section_new(filename, section_line, &n);
+                if (r < 0)
+                        return r;
+
+                qdisc = ordered_hashmap_get(network->qdiscs_by_section, n);
+                if (qdisc) {
+                        *ret = TAKE_PTR(qdisc);
+
+                        return 0;
+                }
+        }
+
+        r = qdisc_new(&qdisc);
+        if (r < 0)
+                return r;
+
+        qdisc->network = network;
+
+        if (filename) {
+                qdisc->section = TAKE_PTR(n);
+
+                r = ordered_hashmap_ensure_allocated(&network->qdiscs_by_section, &network_config_hash_ops);
+                if (r < 0)
+                        return r;
+
+                r = ordered_hashmap_put(network->qdiscs_by_section, qdisc->section, qdisc);
+                if (r < 0)
+                        return r;
+        }
+
+        *ret = TAKE_PTR(qdisc);
+
+        return 0;
+}
+
+void qdisc_free(QDiscs *qdisc) {
+        if (!qdisc)
+                return;
+
+        if (qdisc->network && qdisc->section)
+                ordered_hashmap_remove(qdisc->network->qdiscs_by_section, qdisc->section);
+
+        network_config_section_free(qdisc->section);
+
+        free(qdisc);
+}
+
+static int qdisc_handler(sd_netlink *rtnl, sd_netlink_message *m, Link *link) {
+        int r;
+
+        assert(link);
+        assert(link->qdisc_messages > 0);
+        link->qdisc_messages--;
+
+        if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
+                return 1;
+
+        r = sd_netlink_message_get_errno(m);
+        if (r < 0 && r != -EEXIST) {
+                log_link_error_errno(link, r, "Could not set QDisc: %m");
+                return 1;
+        }
+
+        return 1;
+}
+
+int qdisc_configure(Link *link, QDiscs *qdisc) {
+        _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *req = NULL;
+        int r;
+
+        assert(link);
+        assert(link->manager);
+        assert(link->manager->rtnl);
+        assert(link->ifindex > 0);
+
+        r = sd_rtnl_message_new_qdisc(link->manager->rtnl, &req, RTM_NEWQDISC, qdisc->family, link->ifindex);
+        if (r < 0)
+                return log_link_error_errno(link, r, "Could not create RTM_NEWQDISC message: %m");
+
+        r = sd_rtnl_message_set_qdisc_parent(req, qdisc->parent);
+        if (r < 0)
+                return log_link_error_errno(link, r, "Could not create tcm_parent message: %m");
+
+        if (qdisc->parent == TC_H_CLSACT) {
+                r = sd_rtnl_message_set_qdisc_handle(req, TC_H_MAKE(TC_H_CLSACT, 0));
+                if (r < 0)
+                        return log_link_error_errno(link, r, "Could not set tcm_handle message: %m");
+
+                r = sd_netlink_message_append_string(req, TCA_KIND, "clsact");
+                if (r < 0)
+                        return log_link_error_errno(link, r, "Could not append TCA_KIND attribute: %m");
+        }
+
+        if (qdisc->has_network_emulator) {
+                r = sd_netlink_message_append_string(req, TCA_KIND, "netem");
+                if (r < 0)
+                        return log_link_error_errno(link, r, "Could not append TCA_KIND attribute: %m");
+
+                r = network_emulator_fill_message(link, qdisc, req);
+                if (r < 0)
+                        return r;
+        }
+
+        r = netlink_call_async(link->manager->rtnl, NULL, req, qdisc_handler, link_netlink_destroy_callback, link);
+        if (r < 0)
+                return log_link_error_errno(link, r, "Could not send rtnetlink message: %m");
+
+        link_ref(link);
+        link->qdisc_messages++;
+
+        return 0;
+}
+
+int config_parse_tc_qdiscs_parent(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        _cleanup_(qdisc_free_or_set_invalidp) QDiscs *qdisc = NULL;
+        Network *network = data;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+        assert(data);
+
+        r = qdisc_new_static(network, filename, section_line, &qdisc);
+        if (r < 0)
+                return r;
+
+        if (streq(rvalue, "root"))
+                qdisc->parent = TC_H_ROOT;
+        else if (streq(rvalue, "clsact"))
+                qdisc->parent = TC_H_CLSACT;
+        else {
+                log_syntax(unit, LOG_ERR, filename, line, r,
+                           "Failed to parse [QueueDiscs] 'Parent=', ignoring assignment: %s",
+                           rvalue);
+                return 0;
+        }
+
+        qdisc = NULL;
+
+        return 0;
+}

src/network/tc/qdisc.h

@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: LGPL-2.1+
+ * Copyright © 2019 VMware, Inc. */
+#pragma once
+
+#include "conf-parser.h"
+#include "macro.h"
+#include "netem.h"
+#include "../networkd-util.h"
+
+typedef struct QDiscs QDiscs;
+
+struct QDiscs {
+        NetworkConfigSection *section;
+        Network *network;
+
+        Link *link;
+
+        int family;
+
+        uint32_t handle;
+        uint32_t parent;
+
+        bool has_network_emulator:1;
+
+        NetworkEmulator ne;
+};
+
+void qdisc_free(QDiscs *qdisc);
+int qdisc_new_static(Network *network, const char *filename, unsigned section_line, QDiscs **ret);
+
+int qdisc_configure(Link *link, QDiscs *qdisc);
+
+DEFINE_NETWORK_SECTION_FUNCTIONS(QDiscs, qdisc_free);
+
+CONFIG_PARSER_PROTOTYPE(config_parse_tc_qdiscs_parent);

src/network/tc/tc-util.c

@@ -0,0 +1,63 @@
+/* SPDX-License-Identifier: LGPL-2.1+
+ * Copyright © 2019 VMware, Inc. */
+
+#include "alloc-util.h"
+#include "fileio.h"
+#include "parse-util.h"
+#include "tc-util.h"
+#include "time-util.h"
+
+static int tc_init(double *ticks_in_usec) {
+        uint32_t clock_resolution, ticks_to_usec, usec_to_ticks;
+        _cleanup_free_ char *line = NULL;
+        double clock_factor;
+        int r;
+
+        r = read_one_line_file("/proc/net/psched", &line);
+        if (r < 0)
+                return r;
+
+        r = sscanf(line, "%08x%08x%08x", &ticks_to_usec, &usec_to_ticks, &clock_resolution);
+        if (r < 3)
+                return -EIO;
+
+        clock_factor =  (double) clock_resolution / USEC_PER_SEC;
+        *ticks_in_usec = (double) ticks_to_usec / usec_to_ticks * clock_factor;
+
+        return 0;
+}
+
+int tc_time_to_tick(usec_t t, uint32_t *ret) {
+        static double ticks_in_usec = -1;
+        usec_t a;
+        int r;
+
+        assert(ret);
+
+        if (ticks_in_usec < 0) {
+                r = tc_init(&ticks_in_usec);
+                if (r < 0)
+                        return r;
+        }
+
+        a = t * ticks_in_usec;
+        if (a > UINT32_MAX)
+                return -ERANGE;
+
+        *ret = a;
+        return 0;
+}
+
+int parse_tc_percent(const char *s, uint32_t *percent)  {
+        int r;
+
+        assert(s);
+        assert(percent);
+
+        r = parse_permille(s);
+        if (r < 0)
+                return r;
+
+        *percent = (double) r / 1000 * UINT32_MAX;
+        return 0;
+}

src/network/tc/tc-util.h

@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: LGPL-2.1+
+ * Copyright © 2019 VMware, Inc. */
+#pragma once
+
+#include "time-util.h"
+
+int tc_time_to_tick(usec_t t, uint32_t *ret);
+int parse_tc_percent(const char *s, uint32_t *percent);

src/systemd/sd-netlink.h

@@ -202,6 +202,10 @@ int sd_rtnl_message_routing_policy_rule_get_rtm_type(const sd_netlink_message *m
 int sd_rtnl_message_routing_policy_rule_set_flags(sd_netlink_message *m, unsigned flags);
 int sd_rtnl_message_routing_policy_rule_get_flags(const sd_netlink_message *m, unsigned *flags);
 
+int sd_rtnl_message_new_qdisc(sd_netlink *rtnl, sd_netlink_message **ret, uint16_t nlmsg_type, int tcm_family, int tcm_ifindex);
+int sd_rtnl_message_set_qdisc_parent(sd_netlink_message *m, uint32_t parent);
+int sd_rtnl_message_set_qdisc_handle(sd_netlink_message *m, uint32_t handle);
+
 /* genl */
 int sd_genl_socket_open(sd_netlink **nl);
 int sd_genl_message_new(sd_netlink *nl, sd_genl_family family, uint8_t cmd, sd_netlink_message **m);

test/fuzz/fuzz-network-parser/directives.network

@@ -262,3 +262,9 @@ DNS=
 [NextHop]
 Id=
 Gateway=
+[TrafficControlQueueingDiscipline]
+Parent=
+NetworkEmulatorDelaySec=
+NetworkEmulatorDelayJitterSec=
+NetworkEmulatorLossRate=
+NetworkEmulatorPacketLimit=