network: add MACsecTransmitAssociation.UseForEncoding= setting

man/systemd.netdev.xml

@@ -948,6 +948,14 @@
           unset.</para>
         </listitem>
       </varlistentry>
+      <varlistentry>
+        <term><varname>UseForEncoding=</varname></term>
+        <listitem>
+          <para>Takes a boolean. If enabled, then the security association is used for encoding. Only
+          one <literal>[MACsecTransmitAssociation]</literal> section can enable this option. When enabled,
+          <varname>Activate=yes</varname> is implied. Defaults to unset.</para>
+        </listitem>
+      </varlistentry>
     </variablelist>
   </refsect1>
   <refsect1>

src/network/netdev/macsec.c

@@ -36,6 +36,7 @@ static void security_association_init(SecurityAssociation *sa) {
         assert(sa);
 
         sa->activate = -1;
+        sa->use_for_encoding = -1;
 }
 
 static void macsec_receive_association_free(ReceiveAssociation *c) {
@@ -539,6 +540,10 @@ static int netdev_macsec_fill_message_create(NetDev *netdev, Link *link, sd_netl
                         return log_netdev_error_errno(netdev, r, "Could not append IFLA_MACSEC_ENCRYPT attribute: %m");
         }
 
+        r = sd_netlink_message_append_u8(m, IFLA_MACSEC_ENCODING_SA, v->encoding_an);
+        if (r < 0)
+                return log_netdev_error_errno(netdev, r, "Could not append IFLA_MACSEC_ENCODING_SA attribute: %m");
+
         return r;
 }
 
@@ -919,6 +924,53 @@ int config_parse_macsec_sa_activate(
         return 0;
 }
 
+int config_parse_macsec_use_for_encoding(
+                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_(macsec_transmit_association_free_or_set_invalidp) TransmitAssociation *a = NULL;
+        MACsec *s = userdata;
+        int r;
+
+        assert(filename);
+        assert(section);
+        assert(lvalue);
+        assert(rvalue);
+        assert(data);
+
+        r = macsec_transmit_association_new_static(s, filename, section_line, &a);
+        if (r < 0)
+                return r;
+
+        if (isempty(rvalue))
+                r = -1;
+        else {
+                r = parse_boolean(rvalue);
+                if (r < 0) {
+                        log_syntax(unit, LOG_ERR, filename, line, r,
+                                   "Failed to parse %s= setting. Ignoring assignment: %s",
+                                   lvalue, rvalue);
+                        return 0;
+                }
+        }
+
+        a->sa.use_for_encoding = r;
+        if (a->sa.use_for_encoding > 0)
+                a->sa.activate = true;
+
+        TAKE_PTR(a);
+
+        return 0;
+}
+
 static int macsec_read_key_file(NetDev *netdev, SecurityAssociation *sa) {
         _cleanup_free_ uint8_t *key = NULL;
         size_t key_len;
@@ -1095,7 +1147,8 @@ static int netdev_macsec_verify(NetDev *netdev, const char *filename) {
         ReceiveAssociation *n;
         ReceiveChannel *c;
         Iterator i;
-        uint8_t an;
+        uint8_t an, encoding_an;
+        bool use_for_encoding;
         int r;
 
         assert(netdev);
@@ -1109,6 +1162,8 @@ static int netdev_macsec_verify(NetDev *netdev, const char *filename) {
         }
 
         an = 0;
+        use_for_encoding = false;
+        encoding_an = 0;
         ORDERED_HASHMAP_FOREACH(a, v->transmit_associations_by_section, i) {
                 r = macsec_transmit_association_verify(a);
                 if (r < 0) {
@@ -1126,7 +1181,23 @@ static int netdev_macsec_verify(NetDev *netdev, const char *filename) {
                 }
 
                 a->sa.association_number = an++;
+
+                if (a->sa.use_for_encoding > 0) {
+                        if (use_for_encoding) {
+                                log_netdev_warning(netdev,
+                                                   "%s: Multiple security associations are set to be used for transmit channel."
+                                                   "Disabling UseForEncoding= in [MACsecTransmitAssociation] section from line %u",
+                                                   a->section->filename, a->section->line);
+                                a->sa.use_for_encoding = false;
+                        } else {
+                                encoding_an = a->sa.association_number;
+                                use_for_encoding = true;
                         }
+                }
+        }
+
+        assert(encoding_an < MACSEC_MAX_ASSOCIATION_NUMBER);
+        v->encoding_an = encoding_an;
 
         ORDERED_HASHMAP_FOREACH(n, v->receive_associations_by_section, i) {
                 r = macsec_receive_association_verify(n);

src/network/netdev/macsec.h

@@ -32,6 +32,7 @@ typedef struct SecurityAssociation {
         uint32_t key_len;
         char *key_file;
         int activate;
+        int use_for_encoding;
 } SecurityAssociation;
 
 typedef struct TransmitAssociation {
@@ -63,6 +64,7 @@ struct MACsec {
 
         uint16_t port;
         int encrypt;
+        uint8_t encoding_an;
 
         OrderedHashmap *receive_channels;
         OrderedHashmap *receive_channels_by_section;
@@ -80,3 +82,4 @@ CONFIG_PARSER_PROTOTYPE(config_parse_macsec_key_id);
 CONFIG_PARSER_PROTOTYPE(config_parse_macsec_key);
 CONFIG_PARSER_PROTOTYPE(config_parse_macsec_key_file);
 CONFIG_PARSER_PROTOTYPE(config_parse_macsec_sa_activate);
+CONFIG_PARSER_PROTOTYPE(config_parse_macsec_use_for_encoding);

src/network/netdev/netdev-gperf.gperf

@@ -142,6 +142,7 @@ MACsecTransmitAssociation.KeyId,   config_parse_macsec_key_id,           0,
 MACsecTransmitAssociation.Key,     config_parse_macsec_key,              0,                             0
 MACsecTransmitAssociation.KeyFile, config_parse_macsec_key_file,         0,                             0
 MACsecTransmitAssociation.Activate, config_parse_macsec_sa_activate,     0,                             0
+MACsecTransmitAssociation.UseForEncoding, config_parse_macsec_use_for_encoding, 0,                      0
 MACsecReceiveAssociation.Port,     config_parse_macsec_port,             0,                             0
 MACsecReceiveAssociation.MACAddress, config_parse_macsec_hw_address,     0,                             0
 MACsecReceiveAssociation.PacketNumber, config_parse_macsec_packet_number, 0,                            0

test/fuzz/fuzz-netdev-parser/directives.netdev

@@ -185,6 +185,7 @@ KeyId=
 Key=
 KeyFile=
 Activate=
+UseForEncoding=
 [MACsecReceiveChannel]
 Port=
 MACAddress=