network: do not re-attach sd-event object

Fixes #15126.

man/systemd.network.xml

@@ -2317,6 +2317,16 @@
             the value of a received bit by majority rule. When unset, the kernel's default will be used.</para>
           </listitem>
         </varlistentry>
+        <varlistentry>
+          <term><varname>ListenOnly=</varname></term>
+          <listitem>
+            <para>Takes a boolean. When <literal>yes</literal>, listen-only mode is enabled. When the
+            interface is in listen-only mode, the interface neither transmit CAN frames nor send ACK
+            bit. Listen-only mode is important to debug CAN networks without interfering with the
+            communication or acknowledge the CAN frame. When unset, the kernel's default will be used.
+            </para>
+          </listitem>
+        </varlistentry>
       </variablelist>
   </refsect1>
 

src/network/networkctl.c

@@ -120,6 +120,7 @@ typedef struct LinkInfo {
         unsigned short iftype;
         struct ether_addr mac_address;
         struct ether_addr permanent_mac_address;
+        uint32_t master;
         uint32_t mtu;
         uint32_t min_mtu;
         uint32_t max_mtu;
@@ -342,6 +343,8 @@ static int decode_link(sd_netlink_message *m, LinkInfo *info, char **patterns, b
                         return log_oom();
         }
 
+        (void) sd_netlink_message_read_u32(m, IFLA_MASTER, &info->master);
+
         /* fill kind info */
         (void) decode_netdev(m, info);
 
@@ -1354,6 +1357,15 @@ static int link_status_one(
                         return table_log_add_error(r);
         }
 
+        if (info->master > 0) {
+                r = table_add_many(table,
+                                   TABLE_EMPTY,
+                                   TABLE_STRING, "Master:",
+                                   TABLE_IFINDEX, info->master);
+                if (r < 0)
+                        return table_log_add_error(r);
+        }
+
         if (streq_ptr(info->netdev_kind, "bridge")) {
                 r = table_add_many(table,
                                    TABLE_EMPTY,

src/network/networkd-can.c

@@ -71,6 +71,7 @@ static int link_set_handler(sd_netlink *rtnl, sd_netlink_message *m, Link *link)
 
 static int link_set_can(Link *link) {
         _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;
+        struct can_ctrlmode cm = {};
         int r;
 
         assert(link);
@@ -142,13 +143,18 @@ static int link_set_can(Link *link) {
         }
 
         if (link->network->can_triple_sampling >= 0) {
-                struct can_ctrlmode cm = {
-                        .mask = CAN_CTRLMODE_3_SAMPLES,
-                        .flags = link->network->can_triple_sampling ? CAN_CTRLMODE_3_SAMPLES : 0,
-                };
-
+                cm.mask |= CAN_CTRLMODE_3_SAMPLES;
+                SET_FLAG(cm.flags, CAN_CTRLMODE_3_SAMPLES, link->network->can_triple_sampling);
                 log_link_debug(link, "%sabling triple-sampling", link->network->can_triple_sampling ? "En" : "Dis");
+        }
 
+        if (link->network->can_listen_only >= 0) {
+                cm.mask |= CAN_CTRLMODE_LISTENONLY;
+                SET_FLAG(cm.flags, CAN_CTRLMODE_LISTENONLY, link->network->can_listen_only);
+                log_link_debug(link, "%sabling listen-only mode", link->network->can_listen_only ? "En" : "Dis");
+        }
+
+        if (cm.mask != 0) {
                 r = sd_netlink_message_append_data(m, IFLA_CAN_CTRLMODE, &cm, sizeof(cm));
                 if (r < 0)
                         return log_link_error_errno(link, r, "Could not append IFLA_CAN_CTRLMODE attribute: %m");

src/network/networkd-dhcp4.c

@@ -1334,11 +1334,11 @@ int dhcp4_configure(Link *link) {
                         return log_oom();
                 if (r < 0)
                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to create DHCP4 client: %m");
-        }
 
-        r = sd_dhcp_client_attach_event(link->dhcp_client, NULL, 0);
-        if (r < 0)
-                return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to attach event: %m");
+                r = sd_dhcp_client_attach_event(link->dhcp_client, NULL, 0);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to attach event: %m");
+        }
 
         r = sd_dhcp_client_set_mac(link->dhcp_client,
                                    (const uint8_t *) &link->mac,

src/network/networkd-ipv4ll.c

@@ -154,6 +154,10 @@ int ipv4ll_configure(Link *link) {
                 r = sd_ipv4ll_new(&link->ipv4ll);
                 if (r < 0)
                         return r;
+
+                r = sd_ipv4ll_attach_event(link->ipv4ll, NULL, 0);
+                if (r < 0)
+                        return r;
         }
 
         if (link->sd_device &&
@@ -163,10 +167,6 @@ int ipv4ll_configure(Link *link) {
                         return r;
         }
 
-        r = sd_ipv4ll_attach_event(link->ipv4ll, NULL, 0);
-        if (r < 0)
-                return r;
-
         r = sd_ipv4ll_set_mac(link->ipv4ll, &link->mac);
         if (r < 0)
                 return r;

src/network/networkd-network-gperf.gperf

@@ -256,6 +256,7 @@ CAN.SamplePoint,                             config_parse_permille,
 CAN.RestartSec,                              config_parse_sec,                                         0,                             offsetof(Network, can_restart_us)
 CAN.TripleSampling,                          config_parse_tristate,                                    0,                             offsetof(Network, can_triple_sampling)
 CAN.Termination,                             config_parse_tristate,                                    0,                             offsetof(Network, can_termination)
+CAN.ListenOnly,                              config_parse_tristate,                                    0,                             offsetof(Network, can_listen_only)
 QDisc.Parent,                                config_parse_qdisc_parent,                                _QDISC_KIND_INVALID,           0
 QDisc.Handle,                                config_parse_qdisc_handle,                                _QDISC_KIND_INVALID,           0
 BFIFO.Parent,                                config_parse_qdisc_parent,                                QDISC_KIND_BFIFO,              0

src/network/networkd-network.h

@@ -200,6 +200,7 @@ struct Network {
         usec_t can_restart_us;
         int can_triple_sampling;
         int can_termination;
+        int can_listen_only;
 
         AddressFamily ip_forward;
         bool ip_masquerade;

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

@@ -201,6 +201,7 @@ BitRate=
 RestartSec=
 TripleSampling=
 Termination=
+ListenOnly=
 [Address]
 DuplicateAddressDetection=
 AutoJoin=