KAUTH(9)               NetBSD Kernel Developer's Manual               KAUTH(9)

NAME
     kauth -- kernel authorization framework

SYNOPSIS
     #include <sys/kauth.h>

DESCRIPTION
     kauth, or kernel authorization, is the subsystem managing all authoriza-
     tion requests inside the kernel.  It manages user credentials and rights,
     and can be used to implement a system-wide security policy.  It allows
     external modules to plug-in the authorization process.

     kauth introduces some new concepts, namely ``scopes'' and ``listeners'',
     which will be detailed together with other useful information for kernel
     developers in this document.

   Types
     Some kauth types include the following:

     kauth_cred_t      Representing credentials that can be associated with an
                       object.  Includes user- and group-ids (real, effective,
                       and save) as well as group membership information.

     kauth_scope_t     Describes a scope.

     kauth_listener_t  Describes a listener.

   Terminology
     kauth operates in various ``scopes'', each scope holding a group of
     ``listeners''.

     Each listener works as a callback for when an authorization request
     within the scope is made.  When such a request is made, all listeners on
     the scope are passed common information such as the credentials of the
     request context, an identifier for the requested operation, and possibly
     other information as well.

     Every listener examines the passed information and returns its decision
     regarding the requested operation.  It can either return:

     KAUTH_RESULT_ALLOW  The listener allows the operation.
     KAUTH_RESULT_DENY   The listener denies the operation.
     KAUTH_RESULT_DEFER  The listener defers the decision to other listeners.

     For an operation to be allowed, at least one listener has to return
     KAUTH_RESULT_ALLOW while no other listener returned KAUTH_RESULT_DENY.

     Scopes manage listeners that operate in the same aspect of the system.

   Kernel Programming Interface
     kauth exports a KPI that allows developers both of NetBSD and third-party
     products to authorize requests, access and modify credentials, create and
     remove scopes and listeners, and perform other miscellaneous operations
     on credentials.

   Authorization Requests
     kauth provides a single authorization request routine, which all autho-
     rization requests go through.  This routine dispatches the request to the
     listeners of the appropriate scope, together with four optional user-data
     variables, and returns the augmented result.

     It is declared as

     int kauth_authorize_action(kauth_scope_t scope, kauth_cred_t cred,
     kauth_action_t op, void *arg0, void *arg1, void *arg2, void *arg3)

     An authorization request can return one of two possible values:
     0 (zero)  indicates success; operation is allowed.
     EPERM     indicates failure; operation is denied.  See errno(2).

     Each scope has its own authorization wrapper, to make it easy to call
     from various places by eliminating the need to specify the scope and/or
     cast values.  The authorization wrappers are detailed in each scope's
     section.

     kauth_authorize_action() has several special cases, when it will always
     allow the request.  These are for when the request is issued by the ker-
     nel itself (indicated by the credentials being either NOCRED or FSCRED),
     or when there was no definitive decision from any of the listeners (i.e.,
     it was not explicitly allowed or denied) and no security model was
     loaded.

   Generic Scope
     The generic scope, ``org.netbsd.kauth.generic'', manages generic autho-
     rization requests in the kernel.

     The authorization wrapper for this scope is declared as

     int kauth_authorize_generic(kauth_cred_t cred, kauth_action_t op, void
     *arg0)

     The following operations are available for this scope:

     KAUTH_GENERIC_ISSUSER
              Checks whether the credentials belong to the super-user.

              Using this request is strongly discouraged and should only be
              done as a temporary place-holder, as it is breaking the separa-
              tion between the interface for authorization requests from the
              back-end implementation.

   System Scope
     The system scope, ``org.netbsd.kauth.system'', manages authorization
     requests affecting the entire system.

     The authorization wrapper for this scope is declared as

     int kauth_authorize_system(kauth_cred_t cred, kauth_action_t op, enum
     kauth_system_req req, void *arg1, void *arg2, void *arg3)

     The following requests are available for this scope:

     KAUTH_SYSTEM_ACCOUNTING
              Check if enabling/disabling accounting allowed.

     KAUTH_SYSTEM_CHROOT
              req can be any of the following:

              KAUTH_REQ_SYSTEM_CHROOT_CHROOT
                       Check if calling chroot(2) is allowed.

              KAUTH_REQ_SYSTEM_CHROOT_FCHROOT
                       Check if calling fchroot(2) is allowed.

     KAUTH_SYSTEM_CPU
              Check CPU-manipulation access.

              req can be any of the following:

              KAUTH_REQ_SYSTEM_CPU_SETSTATE
                       Set CPU state, including setting it online or offline.

     KAUTH_SYSTEM_DEBUG
              This request concentrates several debugging-related operations.
              req can be any of the following:

              KAUTH_REQ_SYSTEM_DEBUG_IPKDB
                       Check if using ipkdb(4) is allowed.

     KAUTH_SYSTEM_FILEHANDLE
              Check if filehandle operations allowed.

     KAUTH_SYSTEM_FS_QUOTA
              Check if file-system quota operations are allowed.

              arg1 is a struct mount * describing the file-system mount in
              question.  req can be one of the following:

              KAUTH_REQ_SYSTEM_FS_QUOTA_GET
                       Check if retrieving quota information is allowed.

                       arg2 is a uid_t with the user-id of the user whose
                       quota information is to be retrieved.

              KAUTH_REQ_SYSTEM_FS_QUOTA_ONOFF
                       Check if turning quota on/off is allowed.

              KAUTH_REQ_SYSTEM_FS_QUOTA_MANAGE
                       Check if managing the quota by setting the quota/quota
                       use is allowed.

                       arg2 is a uid_t with the user-id of the user whose
                       quota/quota use is to be set.

              KAUTH_REQ_SYSTEM_FS_QUOTA_NOLIMIT
                       Check if bypassing the quota (not enforcing it) is
                       allowed.

     KAUTH_SYSTEM_FS_RESERVEDSPACE
              Check if using the file-system reserved space is allowed.

     KAUTH_SYSTEM_MODULE
              Check if a module request is allowed.

              arg1 is the command.

     KAUTH_SYSTEM_MKNOD
              Check if creating devices is allowed.

     KAUTH_SYSTEM_MOUNT
              Check if mount-related operations are allowed.

              req can be any of the following:

              KAUTH_REQ_SYSTEM_MOUNT_GET
                       Check if retrieving information about a mount is
                       allowed.  arg1 is a struct mount * with the mount
                       structure in question, arg2 is a void * with file-sys-
                       tem specific data, if any.

              KAUTH_REQ_SYSTEM_MOUNT_NEW
                       Check if mounting a new file-system is allowed.

                       arg1 is the struct vnode * on which the file-system is
                       to be mounted, arg2 is an int with the mount flags, and
                       arg3 is a void * with file-system specific data, if
                       any.

              KAUTH_REQ_SYSTEM_MOUNT_UNMOUNT
                       Checks if unmounting a file-system is allowed.

                       arg1 is a struct mount * with the mount in question.

              KAUTH_REQ_SYSTEM_MOUNT_UPDATE
                       Checks if updating an existing mount is allowed.

                       arg1 is the struct mount * of the existing mount, arg2
                       is an int with the new mount flags, and arg3 is a void
                       * with file-system specific data, if any.

     KAUTH_SYSTEM_PSET
              Check processor-set manipulation.

              req can be any of the following:

              KAUTH_REQ_SYSTEM_PSET_ASSIGN
                       Change processor-set processor assignment.

              KAUTH_REQ_SYSTEM_PSET_BIND
                       Bind an LWP to a processor-set.

              KAUTH_REQ_SYSTEM_PSET_CREATE
                       Create a processor-set.

              KAUTH_REQ_SYSTEM_PSET_DESTROY
                       Destroy a processor-set.

     KAUTH_SYSTEM_REBOOT
              Check if rebooting is allowed.

     KAUTH_SYSTEM_SETIDCORE
              Check if changing coredump settings for set-id processes is
              allowed.

     KAUTH_SYSTEM_SWAPCTL
              Check if privileged swapctl(2) requests are allowed.

     KAUTH_SYSTEM_SYSCTL
              This requests operations related to sysctl(9).  req indicates
              the specific request and can be one of the following:

              KAUTH_REQ_SYSTEM_SYSCTL_ADD
                       Check if adding a sysctl(9) node is allowed.

              KAUTH_REQ_SYSTEM_SYSCTL_DELETE
                       Check if deleting a sysctl(9) node is allowed.

              KAUTH_REQ_SYSTEM_SYSCTL_DESC
                       Check if adding description to a sysctl(9) node is
                       allowed.

              KAUTH_REQ_SYSTEM_SYSCTL_MODIFY
                       Check if modifying a sysctl(9) node variable that
                       doesn't have a custom sysctl helper function is
                       allowed.

                       This request might be deprecated in the future.

              KAUTH_REQ_SYSTEM_SYSCTL_PRVT
                       Check if accessing private sysctl(9) nodes is allowed.

     KAUTH_SYSTEM_TIME
              This request groups time-related operations.  req can be any of
              the following:

              KAUTH_REQ_SYSTEM_TIME_ADJTIME
                       Check if changing the time using adjtime(2) is allowed.

              KAUTH_REQ_SYSTEM_TIME_NTPADJTIME
                       Check if setting the time using ntp_adjtime(2) is
                       allowed.

              KAUTH_REQ_SYSTEM_TIME_SYSTEM
                       Check if changing the time (usually via
                       settimeofday(2)) is allowed.

                       arg1 is a struct timespec * with the new time, arg2 is
                       a struct timeval * with the delta from the current
                       time, arg3 is a bool indicating whether the caller is a
                       device context (e.g.  /dev/clockctl) or not.

              KAUTH_REQ_SYSTEM_TIME_RTCOFFSET
                       Check if changing the RTC offset is allowed.

              KAUTH_REQ_SYSTEM_TIME_TIMECOUNTERS
                       Check if manipulating timecounters is allowed.

   Process Scope
     The process scope, ``org.netbsd.kauth.process'', manages authorization
     requests related to processes in the system.

     The authorization wrapper for this scope is declared as

     int kauth_authorize_process(kauth_cred_t cred, kauth_action_t op, struct
     proc *p, void *arg1, void *arg2, void *arg3)

     The following operations are available for this scope:

     KAUTH_PROCESS_KTRACE
              Checks whether an object with one set of credentials can
              ktrace(1) another process p, possibly with a different set of
              credentials.

              If arg1 is KAUTH_REQ_PROCESS_KTRACE_PERSISTENT, this checks if
              persistent tracing can be done.  Persistent tracing maintains
              the trace across a set-user-id/set-group-id exec(3), and nor-
              mally requires privileged credentials.

     KAUTH_PROCESS_PROCFS
              Checks whether object with passed credentials can use procfs to
              access process p.

              arg1 is the struct pfsnode * for the target element in the tar-
              get process, and arg2 is the access type, which can be either
              KAUTH_REQ_PROCESS_PROCFS_CTL, KAUTH_REQ_PROCESS_PROCFS_READ,
              KAUTH_REQ_PROCESS_PROCFS_RW, or KAUTH_REQ_PROCESS_PROCFS_WRITE,
              indicating control, read, read-write, or write access respec-
              tively.

     KAUTH_PROCESS_PTRACE
              Checks whether object with passed credentials can use ptrace(2)
              to access process p.

              arg1 is the ptrace(2) command.

     KAUTH_PROCESS_CANSEE
              Checks whether an object with one set of credentials can access
              information about another process, possibly with a different set
              of credentials.

              arg1 indicates the class of information being viewed, and can be
              either of KAUTH_REQ_PROCESS_CANSEE_ARGS,
              KAUTH_REQ_PROCESS_CANSEE_ENTRY, KAUTH_REQ_PROCESS_CANSEE_ENV, or
              KAUTH_REQ_PROCESS_CANSEE_OPENFILES.

     KAUTH_PROCESS_SCHEDULER_GETAFFINITY
              Checks whether viewing the scheduler affinity is allowed.

     KAUTH_PROCESS_SCHEDULER_SETAFFINITY
              Checks whether setting the scheduler affinity is allowed.

     KAUTH_PROCESS_SCHEDULER_GETPARAM
              Checks whether viewing the scheduler policy and parameters is
              allowed.

     KAUTH_PROCESS_SCHEDULER_SETPARAM
              Checks whether modifying the scheduler policy and parameters is
              allowed.

     KAUTH_PROCESS_SIGNAL
              Checks whether an object with one set of credentials can post
              signals to another process.

              p is the process the signal is being posted to, and arg1 is the
              signal number.

     KAUTH_PROCESS_CORENAME
              Controls access to process corename.

              arg1 can be KAUTH_REQ_PROCESS_CORENAME_GET or
              KAUTH_REQ_PROCESS_CORENAME_SET, indicating access to read or
              write the process' corename, respectively.

              When modifying the corename, arg2 holds the new corename to be
              used.

     KAUTH_PROCESS_FORK
              Checks if the process can fork.  arg1 is an int indicating how
              many processes exist on the system at the time of the check.

     KAUTH_PROCESS_KEVENT_FILTER
              Checks whether setting a process kevent(2) filter is allowed.

     KAUTH_PROCESS_NICE
              Checks whether the nice value of p can be changed to arg1.

     KAUTH_PROCESS_RLIMIT
              Controls access to process resource limits.

              arg1 can be KAUTH_REQ_PROCESS_RLIMIT_GET or
              KAUTH_REQ_PROCESS_RLIMIT_SET, indicating access to read or write
              the process' resource limits, respectively.

              When modifying resource limits, arg2 is the new value to be used
              and arg3 indicates which resource limit is to be modified.

     KAUTH_PROCESS_SETID
              Check if changing the user- or group-ids, groups, or login-name
              for p is allowed.

     KAUTH_PROCESS_STOPFLAG
              Check if setting the stop flags for exec(3), exit(3), and
              fork(2) is allowed.

              arg1 indicates the flag, and can be either P_STOPEXEC,
              P_STOPEXIT, or P_STOPFORK respectively.

   Network Scope
     The network scope, ``org.netbsd.kauth.network'', manages networking-
     related authorization requests in the kernel.

     The authorization wrapper for this scope is declared as

     int kauth_authorize_network(kauth_cred_t cred, kauth_action_t op, enum
     kauth_network_req req, void *arg1, void *arg2, void *arg3)

     The following operations are available for this scope:

     KAUTH_NETWORK_ALTQ
              Checks if an ALTQ operation is allowed.

              req indicates the ALTQ subsystem in question, and can be one of
              the following:

              KAUTH_REQ_NETWORK_ALTQ_AFMAP
              KAUTH_REQ_NETWORK_ALTQ_BLUE
              KAUTH_REQ_NETWORK_ALTQ_CBQ
              KAUTH_REQ_NETWORK_ALTQ_CDNR
              KAUTH_REQ_NETWORK_ALTQ_CONF
              KAUTH_REQ_NETWORK_ALTQ_FIFOQ
              KAUTH_REQ_NETWORK_ALTQ_HFSC
              KAUTH_REQ_NETWORK_ALTQ_JOBS
              KAUTH_REQ_NETWORK_ALTQ_PRIQ
              KAUTH_REQ_NETWORK_ALTQ_RED
              KAUTH_REQ_NETWORK_ALTQ_RIO
              KAUTH_REQ_NETWORK_ALTQ_WFQ

     KAUTH_NETWORK_BIND
              Checks if a bind(2) request is allowed.

              req allows to indicate the type of the request to structure lis-
              teners and callers easier.  Supported request types:

              KAUTH_REQ_NETWORK_BIND_PORT
                       Checks if binding to a non-privileged/reserved port is
                       allowed.

              KAUTH_REQ_NETWORK_BIND_PRIVPORT
                       Checks if binding to a privileged/reserved port is
                       allowed.

     KAUTH_NETWORK_FIREWALL
              Checks if firewall-related operations are allowed.

              req indicates the sub-action, and can be one of the following:

              KAUTH_REQ_NETWORK_FIREWALL_FW
                       Modification of packet filtering rules.

              KAUTH_REQ_NETWORK_FIREWALL_NAT
                       Modification of NAT rules.

     KAUTH_NETWORK_INTERFACE
              Checks if network interface-related operations are allowed.

              arg1 is (optionally) the struct ifnet * associated with the
              interface.  arg2 is (optionally) an int describing the inter-
              face-specific operation.  arg3 is (optionally) a pointer to the
              interface-specific request structure.  req indicates the sub-
              action, and can be one of the following:

              KAUTH_REQ_NETWORK_INTERFACE_GET
                       Check if retrieving information from the device is
                       allowed.

              KAUTH_REQ_NETWORK_INTERFACE_GETPRIV
                       Check if retrieving privileged information from the
                       device is allowed.

              KAUTH_REQ_NETWORK_INTERFACE_SET
                       Check if setting parameters on the device is allowed.

              KAUTH_REQ_NETWORK_INTERFACE_SETPRIV
                       Check if setting privileged parameters on the device is
                       allowed.

              Note that unless the struct ifnet * for the interface was passed
              in arg1, there's no way to tell what structure arg3 is.

     KAUTH_NETWORK_INTERFACE_PPP
              Checks if operations performed on the ppp(4) network interface
              are allowed.

              req can be one of the following:

              KAUTH_REQ_NETWORK_INTERFACE_PPP_ADD
                       Checks if adding and enabling a ppp(4) interface to the
                       system is allowed.

     KAUTH_NETWORK_INTERFACE_SLIP
              Checks if operations performed on the sl(4) network interface
              are allowed.

              req can be one of the following:

              KAUTH_REQ_NETWORK_INTERFACE_SLIP_ADD
                       Checks if adding and enabling a sl(4) interface to the
                       system is allowed.

     KAUTH_NETWORK_INTERFACE_STRIP
              Checks if operations performed on the strip(4) network interface
              are allowed.

              req can be one of the following:

              KAUTH_REQ_NETWORK_INTERFACE_STRIP_ADD
                       Check if adding and enabling a strip(4) interface to
                       the system is allowed.

     KAUTH_NETWORK_INTERFACE_TUN
              Checks if operations performed on the tun(4) network interface
              are allowed.

              req can be one of the following:

              KAUTH_REQ_NETWORK_INTERFACE_TUN_ADD
                       Checks if adding and enabling a tun(4) interface to the
                       system is allowed.

     KAUTH_NETWORK_FORWSRCRT
              Checks whether status of forwarding of source-routed packets can
              be modified or not.

     KAUTH_NETWORK_NFS
              Check if an NFS related operation is allowed.

              req can be any of the following:

              KAUTH_REQ_NETWORK_NFS_EXPORT
                       Check if modifying the NFS export table is allowed.

              KAUTH_REQ_NETWORK_NFS_SVC
                       Check if access to the NFS nfssvc(2) syscall is
                       allowed.

     KAUTH_NETWORK_ROUTE
              Checks if a routing-related request is allowed.

              arg1 is the struct rt_msghdr * for the request.

     KAUTH_NETWORK_SOCKET
              Checks if a socket related operation is allowed.

              req allows to indicate the type of the request to structure lis-
              teners and callers easier.  Supported request types:

              KAUTH_REQ_NETWORK_SOCKET_RAWSOCK
                       Checks if opening a raw socket is allowed.

              KAUTH_REQ_NETWORK_SOCKET_OPEN
                       Checks if opening a socket is allowed.  arg1, arg2, and
                       arg3 are all int parameters describing the domain,
                       socket type, and protocol, respectively.

              KAUTH_REQ_NETWORK_SOCKET_CANSEE
                       Checks if looking at the socket passed is allowed.

                       arg1 is a struct socket * describing the socket.

              KAUTH_REQ_NETWORK_SOCKET_DROP
                       Checks if a connection can be dropped.

                       arg1 is a struct socket * describing the socket.

              KAUTH_REQ_NETWORK_SOCKET_SETPRIV
                       Checks if setting privileged socket options is allowed.

                       arg1 is a struct socket * describing the socket, arg2
                       is a u_long describing the socket option.

   Machine-dependent Scope
     The machine-dependent (machdep) scope, ``org.netbsd.kauth.machdep'', man-
     ages machine-dependent authorization requests in the kernel.

     The authorization wrapper for this scope is declared as

     int kauth_authorize_machdep(kauth_cred_t cred, kauth_action_t op, void
     *arg0, void *arg1, void *arg2, void *arg3)

     The actions on this scope provide a set that may or may not affect all
     platforms.  Below is a list of available actions, along with which plat-
     forms are affected by each.

     KAUTH_MACHDEP_CPU_UCODE_APPLY
              Request to apply a CPU microcode to a CPU.  This is related to
              the CPU_UCODE kernel config options(4).

     KAUTH_MACHDEP_CACHEFLUSH
              Request to flush the whole CPU cache.  Affects m68k Linux emula-
              tion.

     KAUTH_MACHDEP_IOPERM_GET
              Request to get the I/O permission level.  Affects amd64, i386,
              xen.

     KAUTH_MACHDEP_IOPERM_SET
              Request to set the I/O permission level.  Affects amd64, i386,
              xen.

     KAUTH_MACHDEP_IOPL
              Request to set the I/O privilege level.  Affects amd64, i386,
              xen.

     KAUTH_MACHDEP_LDT_GET
              Request to get the LDT (local descriptor table).  Affects amd64,
              i386, xen.

     KAUTH_MACHDEP_LDT_SET
              Request to set the LDT (local descriptor table).  Affects amd64,
              i386, xen.

     KAUTH_MACHDEP_MTRR_GET
              Request to get the MTRR (memory type range registers).  Affects
              amd64, i386, xen.

     KAUTH_MACHDEP_MTRR_SET
              Request to set the MTRR (memory type range registers).  Affects
              amd64, i386, xen.

     KAUTH_MACHDEP_NVRAM
              Request to access (read/write) the NVRAM.  Affects i386.

     KAUTH_MACHDEP_UNMANAGEDMEM
              Request to access unmanaged memory.  Affects alpha, amd64, arm,
              i386, powerpc, sh3, vax, xen.

   Device Scope
     The device scope, ``org.netbsd.kauth.device'', manages authorization
     requests related to devices on the system.  Devices can be, for example,
     terminals, tape drives, Bluetooth accessories, and any other hardware.
     Network devices specifically are handled by the network scope.

     In addition to the standard authorization wrapper:

     int kauth_authorize_device(kauth_cred_t cred, kauth_action_t op, void
     *arg0, void *arg1, void *arg2, void *arg3)

     this scope provides authorization wrappers for various device types.

     int kauth_authorize_device_tty(kauth_cred_t cred, kauth_action_t op,
     struct tty *tty)

     Authorizes requests for terminal devices on the system.  The third argu-
     ment, tty, is the terminal device in question.  It is passed to the lis-
     tener as arg0.  The second argument, op, is the action and can be one of
     the following:

     KAUTH_DEVICE_TTY_OPEN
              Open the terminal device pointed to by tty.

     KAUTH_DEVICE_TTY_PRIVSET
              Set privileged settings on the terminal device pointed to by
              tty.

     KAUTH_DEVICE_TTY_STI
              Use the ``TIOCSTI'' device ioctl(2), allowing to inject charac-
              ters into the terminal buffer, simulating terminal input.

     int kauth_authorize_device_spec(kauth_cred_t cred, enum kauth_device_req
     req, struct vnode *vp)

     Authorizes requests for special files, usually disk devices, but also
     direct memory access, on the system.

     It passes KAUTH_DEVICE_RAWIO_SPEC as the action to the listener, and
     accepts two arguments.  req, passed to the listener as arg0, is access
     requested, and can be one of KAUTH_REQ_DEVICE_RAWIO_SPEC_READ,
     KAUTH_REQ_DEVICE_RAWIO_SPEC_WRITE, or KAUTH_REQ_DEVICE_RAWIO_SPEC_RW,
     representing read, write, or both read/write access respectively.  vp is
     the vnode of the special file in question, and is passed to the listener
     as arg1.

     Keep in mind that it is the responsibility of the security model devel-
     oper to check whether the underlying device is a disk or the system mem-
     ory, using iskmemdev():

           if ((vp->v_type == VCHR) &&
               iskmemdev(vp->v_un.vu_specinfo->si_rdev))
                   /* system memory access */

     int kauth_authorize_device_passthru(kauth_cred_t cred, dev_t dev, u_long
     mode, void *data)

     Authorizes hardware passthru requests, or user commands passed directly
     to the hardware.  These have the potential of resulting in direct disk
     and/or memory access.

     It passes KAUTH_DEVICE_RAWIO_PASSTHRU as the action to the listener, and
     accepts three arguments.  dev, passed as arg1 to the listener, is the
     device for which the request is made.  mode, passed as arg0 to the lis-
     tener, is a generic representation of the access mode requested.  It can
     be one or more (binary-OR'd) of the following:

           KAUTH_REQ_DEVICE_RAWIO_PASSTHRU_READ
           KAUTH_REQ_DEVICE_RAWIO_PASSTHRU_READCONF
           KAUTH_REQ_DEVICE_RAWIO_PASSTHRU_WRITE
           KAUTH_REQ_DEVICE_RAWIO_PASSTHRU_WRITECONF

     data, passed as arg2 to the listener, is device-specific data that may be
     associated with the request.

   Bluetooth Devices
     Authorizing actions relevant to Bluetooth devices is done using the stan-
     dard authorization wrapper, with the following actions:

     KAUTH_DEVICE_BLUETOOTH_BCSP
              Check if operations on a bcsp(4) device are allowed.

              arg0 is an enum kauth_device_req with one of the following val-
              ues:

              KAUTH_REQ_DEVICE_BLUETOOTH_BCSP_ADD
                       Check if adding and enabling a bcsp(4) device is
                       allowed.

     KAUTH_DEVICE_BLUETOOTH_BTUART
              Check if operations on a btuart(4) device are allowed.

              arg0 is an enum kauth_device_req with one of the following val-
              ues:

              KAUTH_REQ_DEVICE_BLUETOOTH_BTUART_ADD
                       Check if adding and enabling a btuart(4) device is
                       allowed.

     KAUTH_DEVICE_BLUETOOTH_RECV
              Check if a packet can be received from the device.

              arg0 is the packet type.  For HCI_CMD_PKT packets, arg1 is the
              opcode, for HCI_EVENT_PKT packets, arg1 is the event ID, and for
              HCI_ACLDATA_PKT or HCI_SCODATA_PKT packets, arg1 is the connec-
              tion handle.

     KAUTH_DEVICE_BLUETOOTH_SEND
              Check if a packet can be sent to the device.

              arg0 is a struct hci_unit * describing the HCI unit, arg1 is a
              hci_cmd_hdr_t * describing the packet header.

     KAUTH_DEVICE_BLUETOOTH_SETPRIV
              Check if privileged settings can be changed.

              arg0 is a struct hci_unit * describing the HCI unit, arg1 is a
              struct btreq * describing the request, and arg2 is a u_long
              describing the command.

   Kernel random device
     Authorization actions relevant to the kernel random device, rnd(4), is
     done using the standard authorization wrapper, with the following
     actions:

     KAUTH_DEVICE_RND_ADDDATA
              Check if adding data to the entropy pool is allowed.

     KAUTH_DEVICE_RND_GETPRIV
              Check if privileged settings and information can be retrieved.

     KAUTH_DEVICE_RND_SETPRIV
              Check if privileged settings can be changed.

   Credentials Scope
     The credentials scope, ``org.netbsd.kauth.cred'', is a special scope used
     internally by the kauth framework to provide hooking to credential-
     related operations.

     It is a ``notify-only'' scope, allowing hooking operations such as ini-
     tialization of new credentials, credential inheritance during a fork, and
     copying and freeing of credentials.  The main purpose for this scope is
     to give a security model a way to control the aforementioned operations,
     especially in cases where the credentials hold security model-private
     data.

     Notifications are made using the following function, which is internal to
     kauth:

     int kauth_cred_hook(kauth_cred_t cred, kauth_action_t action, void *arg0,
     void *arg1)

     With the following actions:

     KAUTH_CRED_COPY
              The credentials are being copied.  cred are the credentials of
              the lwp context doing the copy, and arg0 and arg1 are both
              kauth_cred_t representing the ``from'' and ``to'' credentials,
              respectively.

     KAUTH_CRED_FORK
              The credentials are being inherited from a parent to a child
              process during a fork.

              cred are the credentials of the lwp context doing the fork, and
              arg0 and arg1 are both struct proc * of the parent and child
              processes, respectively.

     KAUTH_CRED_FREE
              The credentials in cred are being freed.

     KAUTH_CRED_INIT
              The credentials in cred are being initialized.

     Since this is a notify-only scope, all listeners are required to return
     KAUTH_RESULT_ALLOW.

   Credentials Accessors and Mutators
     kauth has a variety of accessor and mutator routines to handle
     kauth_cred_t objects.

     The following routines can be used to access and modify the user- and
     group-ids in a kauth_cred_t:

     uid_t kauth_cred_getuid(kauth_cred_t cred)
              Returns the real user-id from cred.

     uid_t kauth_cred_geteuid(kauth_cred_t cred)
              Returns the effective user-id from cred.

     uid_t kauth_cred_getsvuid(kauth_cred_t cred)
              Returns the saved user-id from cred.

     void kauth_cred_setuid(kauth_cred_t cred, uid_t uid)
              Sets the real user-id in cred to uid.

     void kauth_cred_seteuid(kauth_cred_t cred, uid_t uid)
              Sets the effective user-id in cred to uid.

     void kauth_cred_setsvuid(kauth_cred_t cred, uid_t uid)
              Sets the saved user-id in cred to uid.

     gid_t kauth_cred_getgid(kauth_cred_t cred)
              Returns the real group-id from cred.

     gid_t kauth_cred_getegid(kauth_cred_t cred)
              Returns the effective group-id from cred.

     gid_t kauth_cred_getsvgid(kauth_cred_t cred)
              Returns the saved group-id from cred.

     void kauth_cred_setgid(kauth_cred_t cred, gid_t gid)
              Sets the real group-id in cred to gid.

     void kauth_cred_setegid(kauth_cred_t cred, gid_t gid)
              Sets the effective group-id in cred to gid.

     void kauth_cred_setsvgid(kauth_cred_t cred, gid_t gid)
              Sets the saved group-id in cred to gid.

     u_int kauth_cred_getrefcnt(kauth_cred_t cred)
              Return the reference count for cred.

     The following routines can be used to access and modify the group list in
     a kauth_cred_t:

     int kauth_cred_ismember_gid(kauth_cred_t cred, gid_t gid, int *resultp)
              Checks if the group-id gid is a member in the group list of
              cred.

              If it is, resultp will be set to one, otherwise, to zero.

              The return value is an error code, or zero for success.

     u_int kauth_cred_ngroups(kauth_cred_t cred)
              Return the number of groups in the group list of cred.

     gid_t kauth_cred_group(kauth_cred_t cred, u_int idx)
              Return the group-id of the group at index idx in the group list
              of cred.

     int kauth_cred_setgroups(kauth_cred_t cred, const gid_t *groups, size_t
              ngroups, uid_t gmuid, enum uio_seg seg)
              Copy ngroups groups from array pointed to by groups to the group
              list in cred, adjusting the number of groups in cred appropri-
              ately.  seg should be either UIO_USERSPACE or UIO_SYSSPACE indi-
              cating whether groups is a user or kernel space address.

              Any groups remaining will be set to an invalid value.

              gmuid is unused for now, and to maintain interface compatibility
              with the Darwin KPI.

              The return value is an error code, or zero for success.

     int kauth_cred_getgroups(kauth_cred_t cred, gid_t *groups, size_t
              ngroups, enum uio_seg seg)
              Copy ngroups groups from the group list in cred to the buffer
              pointed to by groups.  seg should be either UIO_USERSPACE or
              UIO_SYSSPACE indicating whether groups is a user or kernel space
              address.

              The return value is an error code, or zero for success.

   Credential Private Data
     kauth provides an interface to allow attaching security-model private
     data to credentials.

     The use of this interface has two parts that can be divided to direct and
     indirect control of the private-data.  Directly controlling the private
     data is done by using the below routines, while the indirect control is
     often dictated by events such as process fork, and is handled by listen-
     ing on the credentials scope (see above).

     Attaching private data to credentials works by registering a key to serve
     as a unique identifier, distinguishing various sets of private data that
     may be associated with the credentials.  Registering, and deregistering,
     a key is done by using these routines:

     int kauth_register_key(const char *name, kauth_key_t *keyp)
              Register new key for private data for name (usually, the secu-
              rity model name).  keyp will be used to return the key to be
              used in further calls.

              The function returns 0 on success and an error code (see
              errno(2)) on failure.

     int kauth_deregister_key(kauth_key_t key)
              Deregister private data key key.

     Once registered, private data may be manipulated by the following rou-
     tines:

     void kauth_cred_setdata(kauth_cred_t cred, kauth_key_t key, void *data)
              Set private data for key in cred to be data.

     void * kauth_cred_getdata(kauth_cred_t cred, kauth_key_t key)
              Retrieve private data for key in cred.

     Note that it is required to use the above routines every time the private
     data is changed, i.e., using kauth_cred_getdata() and later modifying the
     private data should be accompanied by a call to kauth_cred_setdata() with
     the ``new'' private data.

   Credential Inheritance and Reference Counting
     kauth provides an interface for handling shared credentials.

     When a kauth_cred_t is first allocated, its reference count is set to 1.
     However, with time, its reference count can grow as more objects (pro-
     cesses, LWPs, files, etc.) reference it.

     The following routines are available for managing credentials reference
     counting:

     void kauth_cred_hold(kauth_cred_t cred)
              Increases reference count to cred by one.

     void kauth_cred_free(kauth_cred_t cred)
              Decreases the reference count to cred by one.

              If the reference count dropped to zero, the memory used by cred
              will be freed.

     Credential inheritance happens during a fork(2), and is handled by the
     following function:

     void kauth_proc_fork(struct proc *parent, struct proc *child)

     When called, it references the parent's credentials from the child, and
     calls the credentials scope's hook with the KAUTH_CRED_FORK action to
     allow security model-specific handling of the inheritance to take place.

   Credentials Memory Management
     Data-structures for credentials, listeners, and scopes are allocated from
     memory pools managed by the pool(9) subsystem.

     The kauth_cred_t objects have their own memory management routines:

     kauth_cred_t kauth_cred_alloc(void)
              Allocates a new kauth_cred_t, initializes its lock, and sets its
              reference count to one.

   Conversion Routines
     Sometimes it might be necessary to convert a kauth_cred_t to userland's
     view of credentials, a struct uucred, or vice versa.

     The following routines are available for these cases:

     void kauth_uucred_to_cred(kauth_cred_t cred, const struct uucred *uucred)
              Convert userland's view of credentials to a kauth_cred_t.

              This includes effective user- and group-ids, a number of groups,
              and a group list.  The reference count is set to one.

              Note that kauth will try to copy as many groups as can be held
              inside a kauth_cred_t.

     void kauth_cred_to_uucred(struct uucred *uucred, const kauth_cred_t cred)
              Convert kauth_cred_t to userland's view of credentials.

              This includes effective user- and group-ids, a number of groups,
              and a group list.

              Note that kauth will try to copy as many groups as can be held
              inside a struct uucred.

     int kauth_cred_uucmp(kauth_cred_t cred, struct uucred *uucred)
              Compares cred with the userland credentials in uucred.

              Common values that will be compared are effective user- and
              group-ids, and the group list.

   Miscellaneous Routines
     Other routines provided by kauth are:

     void kauth_cred_clone(kauth_cred_t cred1, kauth_cred_t cred2)
              Clone credentials from cred1 to cred2, except for the lock and
              reference count.

     kauth_cred_t kauth_cred_dup(kauth_cred_t cred)
              Duplicate cred.

              What this routine does is call kauth_cred_alloc() followed by a
              call to kauth_cred_clone().

     kauth_cred_t kauth_cred_copy(kauth_cred_t cred)
              Works like kauth_cred_dup(), except for a few differences.

              If cred already has a reference count of one, it will be
              returned.  Otherwise, a new kauth_cred_t will be allocated and
              the credentials from cred will be cloned to it.  Last, a call to
              kauth_cred_free() for cred will be done.

     kauth_cred_t kauth_cred_get(void)
              Return the credentials associated with the current LWP.

   Scope Management
     kauth provides routines to manage the creation and deletion of scopes on
     the system.

     Note that the built-in scopes, the ``generic'' scope and the ``process''
     scope, can't be deleted.

     kauth_scope_t kauth_register_scope(const char *id, kauth_scope_callback_t
              cb, void *cookie)
              Register a new scope on the system.  id is the name of the
              scope, usually in reverse DNS-like notation.  For example,
              ``org.netbsd.kauth.myscope''.  cb is the default listener, to
              which authorization requests for this scope will be dispatched
              to.  cookie is optional user-data that will be passed to all
              listeners during authorization on the scope.

     void kauth_deregister_scope(kauth_scope_t scope)
              Deregister scope from the scopes available on the system, and
              free the kauth_scope_t object scope.

   Listener Management
     Listeners in kauth are authorization callbacks that are called during an
     authorization request in the scope which they belong to.

     When an authorization request is made, all listeners associated with a
     scope are called to allow, deny, or defer the request.

     It is enough for one listener to deny the request in order for the
     request to be denied; but all listeners are called during an authoriza-
     tion process none-the-less.  All listeners are required to allow the
     request for it to be granted, and in a case where all listeners defer the
     request -- leaving the decision for other listeners -- the request is
     denied.

     The following KPI is provided for the management of listeners:

     kauth_listener_t kauth_listen_scope(const char *id,
              kauth_scope_callback_t cb, void *cookie)
              Create a new listener on the scope with the id id, setting the
              default listener to cb.  cookie is optional user-data that will
              be passed to the listener when called during an authorization
              request.

     void kauth_unlisten_scope(kauth_listener_t listener)
              Removes listener from the scope which it belongs to, ensuring it
              won't be called again, and frees the kauth_listener_t object
              listener.

     kauth provides no means for synchronization within listeners.  It is the
     programmer's responsibility to make sure data used by the listener is
     properly locked during its use, as it can be accessed simultaneously from
     the same listener called multiple times.  It is also the programmer's
     responsibility to do garbage collection after the listener, possibly
     freeing any allocated data it used.

     The common method to do the above is by having a reference count to each
     listener.  On entry to the listener, this reference count should be
     raised, and on exit -- lowered.

     During the removal of a listener, first kauth_scope_unlisten() should be
     called to make sure the listener code will not be entered in the future.
     Then, the code should wait (possibly sleeping) until the reference count
     drops to zero.  When that happens, it is safe to do the final cleanup.

     Listeners might sleep, so no locks can be held when calling an authoriza-
     tion wrapper.

EXAMPLES
     Older code had no abstraction of the security model, so most privilege
     checks looked like this:

           if (suser(cred, &acflag) == 0)
                   /* allow privileged operation */

     Using the new interface, you must ask for a specific privilege explic-
     itly.  For example, checking whether it is possible to open a socket
     would look something like this:

           if (kauth_authorize_network(cred, KAUTH_NETWORK_SOCKET,
               KAUTH_REQ_NETWORK_SOCKET_OPEN, PF_INET, SOCK_STREAM,
               IPPROTO_TCP) == 0)
                   /* allow opening the socket */

     Note that the securelevel implications were also integrated into the
     kauth framework so you don't have to note anything special in the call to
     the authorization wrapper, but rather just have to make sure the security
     model handles the request as you expect it to.

     To do that you can just grep(1) in the relevant security model directory
     and have a look at the code.

EXTENDING KAUTH
     Although kauth provides a large set of both detailed and more or less
     generic requests, it might be needed eventually to introduce more scopes,
     actions, or requests.

     Adding a new scope should happen only when an entire subsystem is intro-
     duced and it is assumed other parts of the kernel may want to interfere
     with its inner-workings.  When a subsystem that has the potential of
     impacting the security of the system is introduced, existing security
     modules must be updated to also handle actions on the newly added scope.

     New actions should be added when sets of operations not covered at all
     belong in an already existing scope.

     Requests (or sub-actions) can be added as subsets of existing actions
     when an operation that belongs in an already covered area is introduced.

     Note that all additions should include updates to this manual, the secu-
     rity models shipped with NetBSD, and the example skeleton security model.

SEE ALSO
     secmodel(9)

HISTORY
     The kernel authorization framework first appeared in Mac OS X 10.4.

     The kernel authorization framework in NetBSD first appeared in
     NetBSD 4.0, and is a clean-room implementation based on Apple TN2127,
     available at http://developer.apple.com/technotes/tn2005/tn2127.html

NOTES
     As kauth in NetBSD is still under active development, it is likely that
     the ABI, and possibly the API, will differ between NetBSD versions.
     Developers are to take notice of this fact in order to avoid building
     code that expects one version of the ABI and running it in a system with
     a different one.

AUTHORS
     Elad Efrat <elad@NetBSD.org> implemented the kernel authorization frame-
     work in NetBSD.

     Jason R. Thorpe <thorpej@NetBSD.org> provided guidance and answered ques-
     tions about the Darwin implementation.

ONE MORE THING
     The kauth framework is dedicated to Brian Mitchell, one of the most tal-
     ented people I know.  Thanks for everything.

NetBSD 6.0.1                   January 16, 2012                   NetBSD 6.0.1

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