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diff --git a/ipc/kdbus/Documentation/kdbus.item.xml b/ipc/kdbus/Documentation/kdbus.item.xml new file mode 100644 index 000000000000..09f8b903116f --- /dev/null +++ b/ipc/kdbus/Documentation/kdbus.item.xml @@ -0,0 +1,839 @@ +<?xml version='1.0'?> <!--*-nxml-*--> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> + +<refentry id="kdbus"> + + <refentryinfo> + <title>kdbus.item</title> + <productname>kdbus item</productname> + </refentryinfo> + + <refmeta> + <refentrytitle>kdbus.item</refentrytitle> + <manvolnum>7</manvolnum> + </refmeta> + + <refnamediv> + <refname>kdbus.item</refname> + <refpurpose>kdbus item structure, layout and usage</refpurpose> + </refnamediv> + + <refsect1> + <title>Description</title> + + <para> + To flexibly augment transport structures, data blobs of type + <type>struct kdbus_item</type> can be attached to the structs passed + into the ioctls. Some ioctls make items of certain types mandatory, + others are optional. Items that are unsupported by ioctls they are + attached to will cause the ioctl to fail with <varname>errno</varname> + set to <constant>EINVAL</constant>. + Items are also used for information stored in a connection's + <emphasis>pool</emphasis>, such as received messages, name lists or + requested connection or bus owner information. Depending on the type of + an item, its total size is either fixed or variable. + </para> + + <refsect2> + <title>Chaining items</title> + <para> + Whenever items are used as part of the kdbus kernel API, they are + embedded in structs that are embedded inside structs that themselves + include a size field containing the overall size of the structure. + This allows multiple items to be chained up, and an item iterator + (see below) is capable of detecting the end of an item chain. + </para> + </refsect2> + + <refsect2> + <title>Alignment</title> + <para> + The kernel expects all items to be aligned to 8-byte boundaries. + Unaligned items will cause the ioctl they are used with to fail + with <varname>errno</varname> set to <constant>EINVAL</constant>. + An item that has an unaligned size itself hence needs to be padded + if it is followed by another item. + </para> + </refsect2> + + <refsect2> + <title>Iterating items</title> + <para> + A simple iterator would iterate over the items until the items have + reached the embedding structure's overall size. An example + implementation is shown below. + </para> + + <programlisting><![CDATA[ +#define KDBUS_ALIGN8(val) (((val) + 7) & ~7) + +#define KDBUS_ITEM_NEXT(item) \ + (typeof(item))(((uint8_t *)item) + KDBUS_ALIGN8((item)->size)) + +#define KDBUS_ITEM_FOREACH(item, head, first) \ + for (item = (head)->first; \ + ((uint8_t *)(item) < (uint8_t *)(head) + (head)->size) && \ + ((uint8_t *)(item) >= (uint8_t *)(head)); \ + item = KDBUS_ITEM_NEXT(item)) + ]]></programlisting> + </refsect2> + </refsect1> + + <refsect1> + <title>Item layout</title> + <para> + A <type>struct kdbus_item</type> consists of a + <varname>size</varname> field, describing its overall size, and a + <varname>type</varname> field, both 64 bit wide. They are followed by + a union to store information that is specific to the item's type. + The struct layout is shown below. + </para> + + <programlisting> +struct kdbus_item { + __u64 size; + __u64 type; + /* item payload - see below */ + union { + __u8 data[0]; + __u32 data32[0]; + __u64 data64[0]; + char str[0]; + + __u64 id; + struct kdbus_vec vec; + struct kdbus_creds creds; + struct kdbus_pids pids; + struct kdbus_audit audit; + struct kdbus_caps caps; + struct kdbus_timestamp timestamp; + struct kdbus_name name; + struct kdbus_bloom_parameter bloom_parameter; + struct kdbus_bloom_filter bloom_filter; + struct kdbus_memfd memfd; + int fds[0]; + struct kdbus_notify_name_change name_change; + struct kdbus_notify_id_change id_change; + struct kdbus_policy_access policy_access; + }; +}; + </programlisting> + + <para> + <type>struct kdbus_item</type> should never be used to allocate + an item instance, as its size may grow in future releases of the API. + Instead, it should be manually assembled by storing the + <varname>size</varname>, <varname>type</varname> and payload to a + struct of its own. + </para> + </refsect1> + + <refsect1> + <title>Item types</title> + + <refsect2> + <title>Negotiation item</title> + <variablelist> + <varlistentry> + <term><constant>KDBUS_ITEM_NEGOTIATE</constant></term> + <listitem><para> + With this item is attached to any ioctl, programs can + <emphasis>probe</emphasis> the kernel for known item types. + The item carries an array of <type>uint64_t</type> values in + <varname>item.data64</varname>, each set to an item type to + probe. The kernel will reset each member of this array that is + not recognized as valid item type to <constant>0</constant>. + This way, users can negotiate kernel features at start-up to + keep newer userspace compatible with older kernels. This item + is never attached by the kernel in response to any command. + </para></listitem> + </varlistentry> + </variablelist> + </refsect2> + + <refsect2> + <title>Command specific items</title> + <variablelist> + <varlistentry> + <term><constant>KDBUS_ITEM_PAYLOAD_VEC</constant></term> + <term><constant>KDBUS_ITEM_PAYLOAD_OFF</constant></term> + <listitem><para> + Messages are directly copied by the sending process into the + receiver's + <citerefentry> + <refentrytitle>kdbus.pool</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry>. + This way, two peers can exchange data by effectively doing a + single-copy from one process to another; the kernel will not buffer + the data anywhere else. <constant>KDBUS_ITEM_PAYLOAD_VEC</constant> + is used when <emphasis>sending</emphasis> message. The item + references a memory address when the payload data can be found. + <constant>KDBUS_ITEM_PAYLOAD_OFF</constant> is used when messages + are <emphasis>received</emphasis>, and the + <constant>offset</constant> value describes the offset inside the + receiving connection's + <citerefentry> + <refentrytitle>kdbus.pool</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + where the message payload can be found. See + <citerefentry> + <refentrytitle>kdbus.message</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information on passing of payload data along with a + message. + <programlisting> +struct kdbus_vec { + __u64 size; + union { + __u64 address; + __u64 offset; + }; +}; + </programlisting> + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_PAYLOAD_MEMFD</constant></term> + <listitem><para> + Transports a file descriptor of a <emphasis>memfd</emphasis> in + <type>struct kdbus_memfd</type> in <varname>item.memfd</varname>. + The <varname>size</varname> field has to match the actual size of + the memfd that was specified when it was created. The + <varname>start</varname> parameter denotes the offset inside the + memfd at which the referenced payload starts. See + <citerefentry> + <refentrytitle>kdbus.message</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information on passing of payload data along with a + message. + <programlisting> +struct kdbus_memfd { + __u64 start; + __u64 size; + int fd; + __u32 __pad; +}; + </programlisting> + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_FDS</constant></term> + <listitem><para> + Contains an array of <emphasis>file descriptors</emphasis>. + When used with <constant>KDBUS_CMD_SEND</constant>, the values of + this array must be filled with valid file descriptor numbers. + When received as item attached to a message, the array will + contain the numbers of the installed file descriptors, or + <constant>-1</constant> in case an error occurred. + In either case, the number of entries in the array is derived from + the item's total size. See + <citerefentry> + <refentrytitle>kdbus.message</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information. + </para></listitem> + </varlistentry> + </variablelist> + </refsect2> + + <refsect2> + <title>Items specific to some commands</title> + <variablelist> + <varlistentry> + <term><constant>KDBUS_ITEM_CANCEL_FD</constant></term> + <listitem><para> + Transports a file descriptor that can be used to cancel a + synchronous <constant>KDBUS_CMD_SEND</constant> operation by + writing to it. The file descriptor is stored in + <varname>item.fd[0]</varname>. The item may only contain one + file descriptor. See + <citerefentry> + <refentrytitle>kdbus.message</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information on this item and how to use it. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_BLOOM_PARAMETER</constant></term> + <listitem><para> + Contains a set of <emphasis>bloom parameters</emphasis> as + <type>struct kdbus_bloom_parameter</type> in + <varname>item.bloom_parameter</varname>. + The item is passed from userspace to kernel during the + <constant>KDBUS_CMD_BUS_MAKE</constant> ioctl, and returned + verbatim when <constant>KDBUS_CMD_HELLO</constant> is called. + The kernel does not use the bloom parameters, but they need to + be known by each connection on the bus in order to define the + bloom filter hash details. See + <citerefentry> + <refentrytitle>kdbus.match</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information on matching and bloom filters. + <programlisting> +struct kdbus_bloom_parameter { + __u64 size; + __u64 n_hash; +}; + </programlisting> + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_BLOOM_FILTER</constant></term> + <listitem><para> + Carries a <emphasis>bloom filter</emphasis> as + <type>struct kdbus_bloom_filter</type> in + <varname>item.bloom_filter</varname>. It is mandatory to send this + item attached to a <type>struct kdbus_msg</type>, in case the + message is a signal. This item is never transported from kernel to + userspace. See + <citerefentry> + <refentrytitle>kdbus.match</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information on matching and bloom filters. + <programlisting> +struct kdbus_bloom_filter { + __u64 generation; + __u64 data[0]; +}; + </programlisting> + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_BLOOM_MASK</constant></term> + <listitem><para> + Transports a <emphasis>bloom mask</emphasis> as binary data blob + stored in <varname>item.data</varname>. This item is used to + describe a match into a connection's match database. See + <citerefentry> + <refentrytitle>kdbus.match</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information on matching and bloom filters. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_DST_NAME</constant></term> + <listitem><para> + Contains a <emphasis>well-known name</emphasis> to send a + message to, as null-terminated string in + <varname>item.str</varname>. This item is used with + <constant>KDBUS_CMD_SEND</constant>. See + <citerefentry> + <refentrytitle>kdbus.message</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information on how to send a message. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_MAKE_NAME</constant></term> + <listitem><para> + Contains a <emphasis>bus name</emphasis> or + <emphasis>endpoint name</emphasis>, stored as null-terminated + string in <varname>item.str</varname>. This item is sent from + userspace to kernel when buses or endpoints are created, and + returned back to userspace when the bus creator information is + queried. See + <citerefentry> + <refentrytitle>kdbus.bus</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + and + <citerefentry> + <refentrytitle>kdbus.endpoint</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry>. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_ATTACH_FLAGS_SEND</constant></term> + <term><constant>KDBUS_ITEM_ATTACH_FLAGS_RECV</constant></term> + <listitem><para> + Contains a set of <emphasis>attach flags</emphasis> at + <emphasis>send</emphasis> or <emphasis>receive</emphasis> time. See + <citerefentry> + <refentrytitle>kdbus</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry>, + <citerefentry> + <refentrytitle>kdbus.bus</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> and + <citerefentry> + <refentrytitle>kdbus.connection</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information on attach flags. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_ID</constant></term> + <listitem><para> + Transports a connection's <emphasis>numerical ID</emphasis> of + a connection as <type>uint64_t</type> value in + <varname>item.id</varname>. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_NAME</constant></term> + <listitem><para> + Transports a name associated with the + <emphasis>name registry</emphasis> as null-terminated string as + <type>struct kdbus_name</type> in + <varname>item.name</varname>. The <varname>flags</varname> + contains the flags of the name. See + <citerefentry> + <refentrytitle>kdbus.name</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information on how to access the name registry of a bus. + <programlisting> +struct kdbus_name { + __u64 flags; + char name[0]; +}; + </programlisting> + </para></listitem> + </varlistentry> + </variablelist> + </refsect2> + + <refsect2> + <title>Items attached by the kernel as metadata</title> + + <variablelist> + <varlistentry> + <term><constant>KDBUS_ITEM_TIMESTAMP</constant></term> + <listitem><para> + Contains both the <emphasis>monotonic</emphasis> and the + <emphasis>realtime</emphasis> timestamp, taken when the message + was processed on the kernel side. + Stored as <type>struct kdbus_timestamp</type> in + <varname>item.timestamp</varname>. + <programlisting> +struct kdbus_timestamp { + __u64 seqnum; + __u64 monotonic_ns; + __u64 realtime_ns; +}; + </programlisting> + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_CREDS</constant></term> + <listitem><para> + Contains a set of <emphasis>user</emphasis> and + <emphasis>group</emphasis> information as 32-bit values, in the + usual four flavors: real, effective, saved and filesystem related. + Stored as <type>struct kdbus_creds</type> in + <varname>item.creds</varname>. + <programlisting> +struct kdbus_creds { + __u32 uid; + __u32 euid; + __u32 suid; + __u32 fsuid; + __u32 gid; + __u32 egid; + __u32 sgid; + __u32 fsgid; +}; + </programlisting> + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_PIDS</constant></term> + <listitem><para> + Contains the <emphasis>PID</emphasis>, <emphasis>TID</emphasis> + and <emphasis>parent PID (PPID)</emphasis> of a remote peer. + Stored as <type>struct kdbus_pids</type> in + <varname>item.pids</varname>. + <programlisting> +struct kdbus_pids { + __u64 pid; + __u64 tid; + __u64 ppid; +}; + </programlisting> + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_AUXGROUPS</constant></term> + <listitem><para> + Contains the <emphasis>auxiliary (supplementary) groups</emphasis> + a remote peer is a member of, stored as array of + <type>uint32_t</type> values in <varname>item.data32</varname>. + The array length can be determined by looking at the item's total + size, subtracting the size of the header and dividing the + remainder by <constant>sizeof(uint32_t)</constant>. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_OWNED_NAME</constant></term> + <listitem><para> + Contains a <emphasis>well-known name</emphasis> currently owned + by a connection. The name is stored as null-terminated string in + <varname>item.str</varname>. Its length can also be derived from + the item's total size. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_TID_COMM</constant> [*]</term> + <listitem><para> + Contains the <emphasis>comm</emphasis> string of a task's + <emphasis>TID</emphasis> (thread ID), stored as null-terminated + string in <varname>item.str</varname>. Its length can also be + derived from the item's total size. Receivers of this item should + not use its contents for any kind of security measures. See below. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_PID_COMM</constant> [*]</term> + <listitem><para> + Contains the <emphasis>comm</emphasis> string of a task's + <emphasis>PID</emphasis> (process ID), stored as null-terminated + string in <varname>item.str</varname>. Its length can also be + derived from the item's total size. Receivers of this item should + not use its contents for any kind of security measures. See below. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_EXE</constant> [*]</term> + <listitem><para> + Contains the <emphasis>path to the executable</emphasis> of a task, + stored as null-terminated string in <varname>item.str</varname>. Its + length can also be derived from the item's total size. Receivers of + this item should not use its contents for any kind of security + measures. See below. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_CMDLINE</constant> [*]</term> + <listitem><para> + Contains the <emphasis>command line arguments</emphasis> of a + task, stored as an <emphasis>array</emphasis> of null-terminated + strings in <varname>item.str</varname>. The total length of all + strings in the array can be derived from the item's total size. + Receivers of this item should not use its contents for any kind + of security measures. See below. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_CGROUP</constant></term> + <listitem><para> + Contains the <emphasis>cgroup path</emphasis> of a task, stored + as null-terminated string in <varname>item.str</varname>. Its + length can also be derived from the item's total size. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_CAPS</constant></term> + <listitem><para> + Contains sets of <emphasis>capabilities</emphasis>, stored as + <type>struct kdbus_caps</type> in <varname>item.caps</varname>. + As the item size may increase in the future, programs should be + written in a way that it takes + <varname>item.caps.last_cap</varname> into account, and derive + the number of sets and rows from the item size and the reported + number of valid capability bits. + <programlisting> +struct kdbus_caps { + __u32 last_cap; + __u32 caps[0]; +}; + </programlisting> + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_SECLABEL</constant></term> + <listitem><para> + Contains the <emphasis>LSM label</emphasis> of a task, stored as + null-terminated string in <varname>item.str</varname>. Its length + can also be derived from the item's total size. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_AUDIT</constant></term> + <listitem><para> + Contains the audit <emphasis>sessionid</emphasis> and + <emphasis>loginuid</emphasis> of a task, stored as + <type>struct kdbus_audit</type> in + <varname>item.audit</varname>. + <programlisting> +struct kdbus_audit { + __u32 sessionid; + __u32 loginuid; +}; + </programlisting> + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_CONN_DESCRIPTION</constant></term> + <listitem><para> + Contains the <emphasis>connection description</emphasis>, as set + by <constant>KDBUS_CMD_HELLO</constant> or + <constant>KDBUS_CMD_CONN_UPDATE</constant>, stored as + null-terminated string in <varname>item.str</varname>. Its length + can also be derived from the item's total size. + </para></listitem> + </varlistentry> + </variablelist> + + <para> + All metadata is automatically translated into the + <emphasis>namespaces</emphasis> of the task that receives them. See + <citerefentry> + <refentrytitle>kdbus.message</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information. + </para> + + <para> + [*] Note that the content stored in metadata items of type + <constant>KDBUS_ITEM_TID_COMM</constant>, + <constant>KDBUS_ITEM_PID_COMM</constant>, + <constant>KDBUS_ITEM_EXE</constant> and + <constant>KDBUS_ITEM_CMDLINE</constant> + can easily be tampered by the sending tasks. Therefore, they should + <emphasis>not</emphasis> be used for any sort of security relevant + assumptions. The only reason they are transmitted is to let + receivers know about details that were set when metadata was + collected, even though the task they were collected from is not + active any longer when the items are received. + </para> + </refsect2> + + <refsect2> + <title>Items used for policy entries, matches and notifications</title> + + <variablelist> + <varlistentry> + <term><constant>KDBUS_ITEM_POLICY_ACCESS</constant></term> + <listitem><para> + This item describes a <emphasis>policy access</emphasis> entry to + access the policy database of a + <citerefentry> + <refentrytitle>kdbus.bus</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> or + <citerefentry> + <refentrytitle>kdbus.endpoint</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry>. + Please refer to + <citerefentry> + <refentrytitle>kdbus.policy</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information on the policy database and how to access it. + <programlisting> +struct kdbus_policy_access { + __u64 type; + __u64 access; + __u64 id; +}; + </programlisting> + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_ID_ADD</constant></term> + <term><constant>KDBUS_ITEM_ID_REMOVE</constant></term> + <listitem><para> + This item is sent as attachment to a + <emphasis>kernel notification</emphasis> and indicates that a + new connection was created on the bus, or that a connection was + disconnected, respectively. It stores a + <type>struct kdbus_notify_id_change</type> in + <varname>item.id_change</varname>. + The <varname>id</varname> field contains the numeric ID of the + connection that was added or removed, and <varname>flags</varname> + is set to the connection flags, as passed by + <constant>KDBUS_CMD_HELLO</constant>. See + <citerefentry> + <refentrytitle>kdbus.match</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + and + <citerefentry> + <refentrytitle>kdbus.message</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information on matches and notification messages. + <programlisting> +struct kdbus_notify_id_change { + __u64 id; + __u64 flags; +}; + </programlisting> + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_NAME_ADD</constant></term> + <term><constant>KDBUS_ITEM_NAME_REMOVE</constant></term> + <term><constant>KDBUS_ITEM_NAME_CHANGE</constant></term> + <listitem><para> + This item is sent as attachment to a + <emphasis>kernel notification</emphasis> and indicates that a + <emphasis>well-known name</emphasis> appeared, disappeared or + transferred to another owner on the bus. It stores a + <type>struct kdbus_notify_name_change</type> in + <varname>item.name_change</varname>. + <varname>old_id</varname> describes the former owner of the name + and is set to <constant>0</constant> values in case of + <constant>KDBUS_ITEM_NAME_ADD</constant>. + <varname>new_id</varname> describes the new owner of the name and + is set to <constant>0</constant> values in case of + <constant>KDBUS_ITEM_NAME_REMOVE</constant>. + The <varname>name</varname> field contains the well-known name the + notification is about, as null-terminated string. See + <citerefentry> + <refentrytitle>kdbus.match</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + and + <citerefentry> + <refentrytitle>kdbus.message</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information on matches and notification messages. + <programlisting> +struct kdbus_notify_name_change { + struct kdbus_notify_id_change old_id; + struct kdbus_notify_id_change new_id; + char name[0]; +}; + </programlisting> + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_REPLY_TIMEOUT</constant></term> + <listitem><para> + This item is sent as attachment to a + <emphasis>kernel notification</emphasis>. It informs the receiver + that an expected reply to a message was not received in time. + The remote peer ID and the message cookie are stored in the message + header. See + <citerefentry> + <refentrytitle>kdbus.message</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information about messages, timeouts and notifications. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_ITEM_REPLY_DEAD</constant></term> + <listitem><para> + This item is sent as attachment to a + <emphasis>kernel notification</emphasis>. It informs the receiver + that a remote connection a reply is expected from was disconnected + before that reply was sent. The remote peer ID and the message + cookie are stored in the message header. See + <citerefentry> + <refentrytitle>kdbus.message</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information about messages, timeouts and notifications. + </para></listitem> + </varlistentry> + </variablelist> + </refsect2> + </refsect1> + + <refsect1> + <title>See Also</title> + <simplelist type="inline"> + <member> + <citerefentry> + <refentrytitle>kdbus</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + </member> + <member> + <citerefentry> + <refentrytitle>kdbus.bus</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + </member> + <member> + <citerefentry> + <refentrytitle>kdbus.connection</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + </member> + <member> + <citerefentry> + <refentrytitle>kdbus.endpoint</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + </member> + <member> + <citerefentry> + <refentrytitle>kdbus.fs</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + </member> + <member> + <citerefentry> + <refentrytitle>kdbus.message</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + </member> + <member> + <citerefentry> + <refentrytitle>kdbus.name</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + </member> + <member> + <citerefentry> + <refentrytitle>kdbus.pool</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + </member> + <member> + <citerefentry> + <refentrytitle>memfd_create</refentrytitle> + <manvolnum>2</manvolnum> + </citerefentry> + </member> + </simplelist> + </refsect1> + +</refentry> |