Linux/Documentation/userspace-api/netlink/netlink-raw.rst

Version: ~ [ linux-6.12-rc7 ] ~ [ linux-6.11.7 ] ~ [ linux-6.10.14 ] ~ [ linux-6.9.12 ] ~ [ linux-6.8.12 ] ~ [ linux-6.7.12 ] ~ [ linux-6.6.60 ] ~ [ linux-6.5.13 ] ~ [ linux-6.4.16 ] ~ [ linux-6.3.13 ] ~ [ linux-6.2.16 ] ~ [ linux-6.1.116 ] ~ [ linux-6.0.19 ] ~ [ linux-5.19.17 ] ~ [ linux-5.18.19 ] ~ [ linux-5.17.15 ] ~ [ linux-5.16.20 ] ~ [ linux-5.15.171 ] ~ [ linux-5.14.21 ] ~ [ linux-5.13.19 ] ~ [ linux-5.12.19 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.229 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.285 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.323 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.336 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.337 ] ~ [ linux-4.4.302 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.12 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

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1 .. SPDX-License-Identifier: BSD-3-Clause 1 .. SPDX-License-Identifier: BSD-3-Clause 2 2 3 ============================================== 3 ====================================================== 4 Netlink specification support for raw Netlink 4 Netlink specification support for raw Netlink families 5 ============================================== 5 ====================================================== 6 6 7 This document describes the additional propert 7 This document describes the additional properties required by raw Netlink 8 families such as ``NETLINK_ROUTE`` which use t 8 families such as ``NETLINK_ROUTE`` which use the ``netlink-raw`` protocol 9 specification. 9 specification. 10 10 11 Specification 11 Specification 12 ============= 12 ============= 13 13 14 The netlink-raw schema extends the :doc:`genet 14 The netlink-raw schema extends the :doc:`genetlink-legacy <genetlink-legacy>` 15 schema with properties that are needed to spec 15 schema with properties that are needed to specify the protocol numbers and 16 multicast IDs used by raw netlink families. Se 16 multicast IDs used by raw netlink families. See :ref:`classic_netlink` for more 17 information. The raw netlink families also mak !! 17 information. 18 sub-messages. << 19 18 20 Globals 19 Globals 21 ------- 20 ------- 22 21 23 protonum 22 protonum 24 ~~~~~~~~ 23 ~~~~~~~~ 25 24 26 The ``protonum`` property is used to specify t 25 The ``protonum`` property is used to specify the protocol number to use when 27 opening a netlink socket. 26 opening a netlink socket. 28 27 29 .. code-block:: yaml 28 .. code-block:: yaml 30 29 31 # SPDX-License-Identifier: ((GPL-2.0 WITH Li 30 # SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 32 31 33 name: rt-addr 32 name: rt-addr 34 protocol: netlink-raw 33 protocol: netlink-raw 35 protonum: 0 # part of the NETLIN 34 protonum: 0 # part of the NETLINK_ROUTE protocol 36 35 37 36 38 Multicast group properties 37 Multicast group properties 39 -------------------------- 38 -------------------------- 40 39 41 value 40 value 42 ~~~~~ 41 ~~~~~ 43 42 44 The ``value`` property is used to specify the 43 The ``value`` property is used to specify the group ID to use for multicast 45 group registration. 44 group registration. 46 45 47 .. code-block:: yaml 46 .. code-block:: yaml 48 47 49 mcast-groups: 48 mcast-groups: 50 list: 49 list: 51 - 50 - 52 name: rtnlgrp-ipv4-ifaddr 51 name: rtnlgrp-ipv4-ifaddr 53 value: 5 52 value: 5 54 - 53 - 55 name: rtnlgrp-ipv6-ifaddr 54 name: rtnlgrp-ipv6-ifaddr 56 value: 9 55 value: 9 57 - 56 - 58 name: rtnlgrp-mctp-ifaddr 57 name: rtnlgrp-mctp-ifaddr 59 value: 34 58 value: 34 60 << 61 Sub-messages << 62 ------------ << 63 << 64 Several raw netlink families such as << 65 :doc:`rt_link<../../networking/netlink_spec/rt << 66 :doc:`tc<../../networking/netlink_spec/tc>` us << 67 abstraction to carry module specific informati << 68 << 69 Conceptually it looks as follows:: << 70 << 71 [OUTER NEST OR MESSAGE LEVEL] << 72 [GENERIC ATTR 1] << 73 [GENERIC ATTR 2] << 74 [GENERIC ATTR 3] << 75 [GENERIC ATTR - wrapper] << 76 [MODULE SPECIFIC ATTR 1] << 77 [MODULE SPECIFIC ATTR 2] << 78 << 79 The ``GENERIC ATTRs`` at the outer level are d << 80 core TC), while specific drivers, TC classifie << 81 own information wrapped in the ``GENERIC ATTR << 82 example above shows attributes nesting inside << 83 have full freedom to define the format of the << 84 the wrapper attr has very similar characterist << 85 contain a fixed header / structure, netlink at << 86 those shared characteristics we refer to the p << 87 a sub-message. << 88 << 89 A sub-message attribute uses the value of anot << 90 choose the right sub-message format. For examp << 91 already been decoded: << 92 << 93 .. code-block:: json << 94 << 95 { "kind": "gre" } << 96 << 97 and we encounter the following attribute spec: << 98 << 99 .. code-block:: yaml << 100 << 101 - << 102 name: data << 103 type: sub-message << 104 sub-message: linkinfo-data-msg << 105 selector: kind << 106 << 107 Then we look for a sub-message definition call << 108 the value of the ``kind`` attribute i.e. ``gre << 109 correct format for the sub-message: << 110 << 111 .. code-block:: yaml << 112 << 113 sub-messages: << 114 name: linkinfo-data-msg << 115 formats: << 116 - << 117 value: bridge << 118 attribute-set: linkinfo-bridge-attrs << 119 - << 120 value: gre << 121 attribute-set: linkinfo-gre-attrs << 122 - << 123 value: geneve << 124 attribute-set: linkinfo-geneve-attrs << 125 << 126 This would decode the attribute value as a sub << 127 called ``linkinfo-gre-attrs`` as the attribute << 128 << 129 A sub-message can have an optional ``fixed-hea << 130 attributes from an ``attribute-set``. For exam << 131 ``tc-options-msg`` sub-message defines message << 132 ``fixed-header``, ``attribute-set`` or both to << 133 << 134 .. code-block:: yaml << 135 << 136 sub-messages: << 137 - << 138 name: tc-options-msg << 139 formats: << 140 - << 141 value: bfifo << 142 fixed-header: tc-fifo-qopt << 143 - << 144 value: cake << 145 attribute-set: tc-cake-attrs << 146 - << 147 value: netem << 148 fixed-header: tc-netem-qopt << 149 attribute-set: tc-netem-attrs << 150 << 151 Note that a selector attribute must appear in << 152 sub-message attributes that depend on it. << 153 << 154 If an attribute such as ``kind`` is defined at << 155 sub-message selector will be resolved using th << 156 For example, if the same attribute name is def << 157 alongside a sub-message selector and also in a << 158 the selector will be resolved using the value << 159 value is not present in the message at the sam << 160 then this is an error. << 161 << 162 Nested struct definitions << 163 ------------------------- << 164 << 165 Many raw netlink families such as :doc:`tc<../ << 166 make use of nested struct definitions. The ``n << 167 possible to embed a struct within a struct def << 168 property. For example, the following struct de << 169 ``tc-ratespec`` struct definition for both the << 170 members of ``struct tc-tbf-qopt``. << 171 << 172 .. code-block:: yaml << 173 << 174 - << 175 name: tc-tbf-qopt << 176 type: struct << 177 members: << 178 - << 179 name: rate << 180 type: binary << 181 struct: tc-ratespec << 182 - << 183 name: peakrate << 184 type: binary << 185 struct: tc-ratespec << 186 - << 187 name: limit << 188 type: u32 << 189 - << 190 name: buffer << 191 type: u32 << 192 - << 193 name: mtu << 194 type: u32 <<

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