../svn-commit.tmp
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Martin Willi
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strongSwans overall design
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============================
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IKEv1 and IKEv2 is handled in different keying daemons. The ole IKEv1 stuff is
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completely handled in pluto, as it was all the times. IKEv2 is handled in the
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new keying daemon, which is called charon.
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Daemon control is done over unix sockets. Pluto uses whack, as it did for years.
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Charon uses another socket interface, called stroke. Stroke uses another
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format as whack and therefore is not compatible to whack. The starter utility,
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wich does fast configuration parsing, speaks both the protocols, whack and
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stroke. It also handles daemon startup and termination.
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Pluto uses starter for some commands, for other it uses the whack utility. To be
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as close to pluto as possible, charon has the same split up of commands to
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starter and stroke. All commands are wrapped together in the ipsec script, which
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allows transparent control of both daemons.
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+-----------------------------------------+
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| ipsec |
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+-----+--------------+---------------+----+
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| | |
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| | |
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| +-----+-----+ |
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+-----+----+ | | +-----+----+
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| | | starter | | |
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| stroke | | | | whack |
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| | +---+--+----+ | |
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+------+---+ | | +--+-------+
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| | | |
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+---+------+ | | +------+--+
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| | | | | |
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| charon +----+ +----+ pluto |
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| | | |
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+-----+----+ +----+----+
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| |
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+-----+----+ |
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| LSF | |
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+-----+----+ |
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| |
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+-----+----+ +----+----+
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| RAW Sock | | UDP/500 |
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+----------+ +---------+
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Since IKEv2 uses the same port as IKEv1, both daemons must listen to UDP port
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500. Under Linux, there is no clean way to set up two sockets at the same port.
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To reslove this problem, charon uses a RAW socket, as they are used in network
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sniffers. An installed Linux Socket Filter (LSF) filters out all none-IKEv2
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traffic. Pluto receives any IKE message, independant of charons behavior.
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Therefore plutos behavior is changed to discard any IKEv2 traffic silently.
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IKEv2 keying daemon: charon
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=============================
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Threading modell
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------------------
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All IKEv2 stuff is handled in charon. It uses a newer and more flexible
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architecture than pluto. Charon uses a thread-pool, which allows parallel
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execution SA-management. Beside the thread-pool, there are some special purpose
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threads which do their job for the common health of the daemon.
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+------+
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| E Q |
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| v u |---+ +------+ +------+
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| e e | | | | | IKE- |
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| n u | +-----------+ | |--| SA |
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| t e | | | | I M | +------+
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+------------+ | - | | Scheduler | | K a |
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| receiver | +------+ | | | E n | +------+
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+----+-------+ +-----------+ | - a | | IKE- |
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| | +------+ | | S g |--| SA |
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+-------+--+ +-----| J Q |---+ +------------+ | A e | +------+
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-| socket | | o u | | | | - r |
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+-------+--+ | b e | | Thread- | | |
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| | - u | | Pool | | |
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+----+-------+ | e |------| |---| |
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| sender | +------+ +------------+ +------+
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+----+-------+
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| +------+
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| | S Q |
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| | e u |
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| | n e |
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+------------| d u |
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| - e |
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+--+---+
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The thread-pool is the heart of the architecture. It processes jobs from a
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(fully synchronized) job-queue. Mostly, a job is associated with a specific
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IKE SA. These IKE SAs are synchronized, only one thread can work one an IKE SA.
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This makes it unnecesary to use further synchronisation methods once a IKE SA
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is checked out. The (rather complex) synchronization of IKE SAs is completely
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done in the IKE SA manager.
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The sceduler is responsible for event firing. It waits until a event in the
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(fully synchronized) event-queue is ready for processing and pushes the event
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down to the job-queue. A thread form the pool will pick it up as quick as
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possible. Every thread can queue events or jobs. Furter, an event can place a
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packet in the send-queue. The sender thread waits for those packets and sends
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them over the wire, via the socket. The receiver does exactly the opposite of
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the sender. It waits on the socket, reads in packets an places them on the
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job-queue for further processing by a thread from the pool.
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There are even more threads, not drawn in the upper scheme. The stroke thread
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is responsible for reading and processessing commands from another process. The
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kernel interface thread handles communication from and to the kernel via a
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netlink socket. It waits for kernel events and processes them appropriately.
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configuration backends
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------------------------
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The configuration architecture for charon is complex, but is flexible and
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extensible. All configuration stuff is split up in multiple parts:
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connection Defines a connection between two hosts. Proposals define with
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wich algorithms a IKE SA should be set up.
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policy Defines the rules to apply ontop of a connection. A policy is
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defined between two IDs. Proposals and traffic selectors allow
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fine grained configuration of the CHILD SAs (AH and ESP) to set
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up.
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credential A credential is something used for authentication, such as a
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preshared key, a RSA private or public key, certificate, ...
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configuration The configuration itself handles daemon related configuration
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stuff, such as interface binding or logging settings.
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These configuration types are defined as interfaces, and are currently
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implemented only in the stroke class. Through the modular design, parts could be
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replaced with more powerful backends, such as a RADIUS server for the
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credentials, a SQL database for the connections, policy definitions on an LDAP
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server, and so on...
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@@ -0,0 +1,5 @@
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Known bugs in charon
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======================
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- intiating the same connection twice makes trouble.
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-
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@@ -0,0 +1,44 @@
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TODO-List for charon
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======================
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+ = done, - = todo, ordered by priority
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+ private key loading: der, without passphrase
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+ load all private keys from ipsec.d/private/ in stroke.c
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+ handle leftcert and rightcert in starterstroke.c/stroke.c
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+ load specified certs in stroke.c
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+ extract public keys from certs
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+ public key authentication
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+ release for Andreas
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+ stroke loglevels
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+ stroke up
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+ ike_sa_manager checkout_by_hosts
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+ stroke down
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+ stroke output redirection
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+ stroke status
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- libx509
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+ new charon build - libstrong?
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+ transforms
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+ utils (plus host)
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- doxygen fixes (two doxyfiles?)
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- allocator cleanup (used in lib, charon and pluto(!))
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- logger reimplementation? (one logger for lib, charon, pluto)
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- integrate asn1 parser/oid (asn1/oid)
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- integrate PEM loading (pem)
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- ... (more to come, for sure)
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- ipsec.secrets parsing
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- certificate DN parsing
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- certificate subjectAltName parsing
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- certificate lookup via ID
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- certificate validation/chaining
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- certificate exchange
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- trapping
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- delete notify, when to send?
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- notifys on connection setup failure
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- create child sa message
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