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[netbsd-mini2440.git] / sys / kern / kern_auth.c

/* $NetBSD: kern_auth.c,v 1.64 2009/09/03 04:45:27 elad Exp $ */

/*-
 * Copyright (c) 2006, 2007 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*-
 * Copyright (c) 2005, 2006 Elad Efrat <elad@NetBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_auth.c,v 1.64 2009/09/03 04:45:27 elad Exp $");

#include <sys/types.h>
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/proc.h>
#include <sys/ucred.h>
#include <sys/pool.h>
#include <sys/kauth.h>
#include <sys/kmem.h>
#include <sys/rwlock.h>
#include <sys/sysctl.h>
#include <sys/atomic.h>
#include <sys/specificdata.h>
#include <sys/vnode.h>

/*
 * Secmodel-specific credentials.
 */
struct kauth_key {
        const char *ks_secmodel;        /* secmodel */
        specificdata_key_t ks_key;      /* key */
};

/* 
 * Credentials.
 *
 * A subset of this structure is used in kvm(3) (src/lib/libkvm/kvm_proc.c)
 * and should be synchronized with this structure when the update is
 * relevant.
 */
struct kauth_cred {
        /*
         * Ensure that the first part of the credential resides in its own
         * cache line.  Due to sharing there aren't many kauth_creds in a
         * typical system, but the reference counts change very often.
         * Keeping it seperate from the rest of the data prevents false
         * sharing between CPUs.
         */
        u_int cr_refcnt;                /* reference count */
#if COHERENCY_UNIT > 4
        uint8_t cr_pad[COHERENCY_UNIT - 4];
#endif
        uid_t cr_uid;                   /* user id */
        uid_t cr_euid;                  /* effective user id */
        uid_t cr_svuid;                 /* saved effective user id */
        gid_t cr_gid;                   /* group id */
        gid_t cr_egid;                  /* effective group id */
        gid_t cr_svgid;                 /* saved effective group id */
        u_int cr_ngroups;               /* number of groups */
        gid_t cr_groups[NGROUPS];       /* group memberships */
        specificdata_reference cr_sd;   /* specific data */
};

/*
 * Listener.
 */
struct kauth_listener {
        kauth_scope_callback_t          func;           /* callback */
        kauth_scope_t                   scope;          /* scope backpointer */
        u_int                           refcnt;         /* reference count */
        SIMPLEQ_ENTRY(kauth_listener)   listener_next;  /* listener list */
};

/*
 * Scope.
 */
struct kauth_scope {
        const char                     *id;             /* scope name */
        void                           *cookie;         /* user cookie */
        u_int                           nlisteners;     /* # of listeners */
        SIMPLEQ_HEAD(, kauth_listener)  listenq;        /* listener list */
        SIMPLEQ_ENTRY(kauth_scope)      next_scope;     /* scope list */
};

static int kauth_cred_hook(kauth_cred_t, kauth_action_t, void *, void *);

/* List of scopes and its lock. */
static SIMPLEQ_HEAD(, kauth_scope) scope_list =
    SIMPLEQ_HEAD_INITIALIZER(scope_list);

/* Built-in scopes: generic, process. */
static kauth_scope_t kauth_builtin_scope_generic;
static kauth_scope_t kauth_builtin_scope_system;
static kauth_scope_t kauth_builtin_scope_process;
static kauth_scope_t kauth_builtin_scope_network;
static kauth_scope_t kauth_builtin_scope_machdep;
static kauth_scope_t kauth_builtin_scope_device;
static kauth_scope_t kauth_builtin_scope_cred;
static kauth_scope_t kauth_builtin_scope_vnode;

static unsigned int nsecmodels = 0;

static specificdata_domain_t kauth_domain;
static pool_cache_t kauth_cred_cache;

krwlock_t       kauth_lock;

/* Allocate new, empty kauth credentials. */
kauth_cred_t
kauth_cred_alloc(void)
{
        kauth_cred_t cred;

        cred = pool_cache_get(kauth_cred_cache, PR_WAITOK);

        cred->cr_refcnt = 1;
        cred->cr_uid = 0;
        cred->cr_euid = 0;
        cred->cr_svuid = 0;
        cred->cr_gid = 0;
        cred->cr_egid = 0;
        cred->cr_svgid = 0;
        cred->cr_ngroups = 0;

        specificdata_init(kauth_domain, &cred->cr_sd);
        kauth_cred_hook(cred, KAUTH_CRED_INIT, NULL, NULL);

        return (cred);
}

/* Increment reference count to cred. */
void
kauth_cred_hold(kauth_cred_t cred)
{
        KASSERT(cred != NULL);
        KASSERT(cred->cr_refcnt > 0);

        atomic_inc_uint(&cred->cr_refcnt);
}

/* Decrease reference count to cred. If reached zero, free it. */
void
kauth_cred_free(kauth_cred_t cred)
{

        KASSERT(cred != NULL);
        KASSERT(cred->cr_refcnt > 0);
        ASSERT_SLEEPABLE();

        if (atomic_dec_uint_nv(&cred->cr_refcnt) > 0)
                return;

        kauth_cred_hook(cred, KAUTH_CRED_FREE, NULL, NULL);
        specificdata_fini(kauth_domain, &cred->cr_sd);
        pool_cache_put(kauth_cred_cache, cred);
}

static void
kauth_cred_clone1(kauth_cred_t from, kauth_cred_t to, bool copy_groups)
{
        KASSERT(from != NULL);
        KASSERT(to != NULL);
        KASSERT(from->cr_refcnt > 0);

        to->cr_uid = from->cr_uid;
        to->cr_euid = from->cr_euid;
        to->cr_svuid = from->cr_svuid;
        to->cr_gid = from->cr_gid;
        to->cr_egid = from->cr_egid;
        to->cr_svgid = from->cr_svgid;
        if (copy_groups) {
                to->cr_ngroups = from->cr_ngroups;
                memcpy(to->cr_groups, from->cr_groups, sizeof(to->cr_groups));
        }

        kauth_cred_hook(from, KAUTH_CRED_COPY, to, NULL);
}

void
kauth_cred_clone(kauth_cred_t from, kauth_cred_t to)
{
        kauth_cred_clone1(from, to, true);
}

/*
 * Duplicate cred and return a new kauth_cred_t.
 */
kauth_cred_t
kauth_cred_dup(kauth_cred_t cred)
{
        kauth_cred_t new_cred;

        KASSERT(cred != NULL);
        KASSERT(cred->cr_refcnt > 0);

        new_cred = kauth_cred_alloc();

        kauth_cred_clone(cred, new_cred);

        return (new_cred);
}

/*
 * Similar to crcopy(), only on a kauth_cred_t.
 * XXX: Is this even needed? [kauth_cred_copy]
 */
kauth_cred_t
kauth_cred_copy(kauth_cred_t cred)
{
        kauth_cred_t new_cred;

        KASSERT(cred != NULL);
        KASSERT(cred->cr_refcnt > 0);

        /* If the provided credentials already have one reference, use them. */
        if (cred->cr_refcnt == 1)
                return (cred);

        new_cred = kauth_cred_alloc();

        kauth_cred_clone(cred, new_cred);

        kauth_cred_free(cred);

        return (new_cred);
}

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

        mutex_enter(parent->p_lock);
        kauth_cred_hold(parent->p_cred);
        child->p_cred = parent->p_cred;
        mutex_exit(parent->p_lock);

        /* XXX: relies on parent process stalling during fork() */
        kauth_cred_hook(parent->p_cred, KAUTH_CRED_FORK, parent,
            child);
}

uid_t
kauth_cred_getuid(kauth_cred_t cred)
{
        KASSERT(cred != NULL);

        return (cred->cr_uid);
}

uid_t
kauth_cred_geteuid(kauth_cred_t cred)
{
        KASSERT(cred != NULL);

        return (cred->cr_euid);
}

uid_t
kauth_cred_getsvuid(kauth_cred_t cred)
{
        KASSERT(cred != NULL);

        return (cred->cr_svuid);
}

gid_t
kauth_cred_getgid(kauth_cred_t cred)
{
        KASSERT(cred != NULL);

        return (cred->cr_gid);
}

gid_t
kauth_cred_getegid(kauth_cred_t cred)
{
        KASSERT(cred != NULL);

        return (cred->cr_egid);
}

gid_t
kauth_cred_getsvgid(kauth_cred_t cred)
{
        KASSERT(cred != NULL);

        return (cred->cr_svgid);
}

void
kauth_cred_setuid(kauth_cred_t cred, uid_t uid)
{
        KASSERT(cred != NULL);
        KASSERT(cred->cr_refcnt == 1);

        cred->cr_uid = uid;
}

void
kauth_cred_seteuid(kauth_cred_t cred, uid_t uid)
{
        KASSERT(cred != NULL);
        KASSERT(cred->cr_refcnt == 1);

        cred->cr_euid = uid;
}

void
kauth_cred_setsvuid(kauth_cred_t cred, uid_t uid)
{
        KASSERT(cred != NULL);
        KASSERT(cred->cr_refcnt == 1);

        cred->cr_svuid = uid;
}

void
kauth_cred_setgid(kauth_cred_t cred, gid_t gid)
{
        KASSERT(cred != NULL);
        KASSERT(cred->cr_refcnt == 1);

        cred->cr_gid = gid;
}

void
kauth_cred_setegid(kauth_cred_t cred, gid_t gid)
{
        KASSERT(cred != NULL);
        KASSERT(cred->cr_refcnt == 1);

        cred->cr_egid = gid;
}

void
kauth_cred_setsvgid(kauth_cred_t cred, gid_t gid)
{
        KASSERT(cred != NULL);
        KASSERT(cred->cr_refcnt == 1);

        cred->cr_svgid = gid;
}

/* Checks if gid is a member of the groups in cred. */
int
kauth_cred_ismember_gid(kauth_cred_t cred, gid_t gid, int *resultp)
{
        uint32_t i;

        KASSERT(cred != NULL);
        KASSERT(resultp != NULL);

        *resultp = 0;

        for (i = 0; i < cred->cr_ngroups; i++)
                if (cred->cr_groups[i] == gid) {
                        *resultp = 1;
                        break;
                }

        return (0);
}

u_int
kauth_cred_ngroups(kauth_cred_t cred)
{
        KASSERT(cred != NULL);

        return (cred->cr_ngroups);
}

/*
 * Return the group at index idx from the groups in cred.
 */
gid_t
kauth_cred_group(kauth_cred_t cred, u_int idx)
{
        KASSERT(cred != NULL);
        KASSERT(idx < cred->cr_ngroups);

        return (cred->cr_groups[idx]);
}

/* XXX elad: gmuid is unused for now. */
int
kauth_cred_setgroups(kauth_cred_t cred, const gid_t *grbuf, size_t len,
    uid_t gmuid, enum uio_seg seg)
{
        int error = 0;

        KASSERT(cred != NULL);
        KASSERT(cred->cr_refcnt == 1);

        if (len > __arraycount(cred->cr_groups))
                return EINVAL;

        if (len) {
                if (seg == UIO_SYSSPACE) {
                        memcpy(cred->cr_groups, grbuf,
                            len * sizeof(cred->cr_groups[0]));
                } else {
                        error = copyin(grbuf, cred->cr_groups,
                            len * sizeof(cred->cr_groups[0]));
                        if (error != 0)
                                len = 0;
                }
        }
        memset(cred->cr_groups + len, 0xff,
            sizeof(cred->cr_groups) - (len * sizeof(cred->cr_groups[0])));

        cred->cr_ngroups = len;

        return error;
}

/* This supports sys_setgroups() */
int
kauth_proc_setgroups(struct lwp *l, kauth_cred_t ncred)
{
        kauth_cred_t cred;
        int error;

        /*
         * At this point we could delete duplicate groups from ncred,
         * and plausibly sort the list - but in general the later is
         * a bad idea.
         */
        proc_crmod_enter();
        /* Maybe we should use curproc here ? */
        cred = l->l_proc->p_cred;

        kauth_cred_clone1(cred, ncred, false);

        error = kauth_authorize_process(cred, KAUTH_PROCESS_SETID,
            l->l_proc, NULL, NULL, NULL);
        if (error != 0) {
                proc_crmod_leave(cred, ncred, false);
                        return error;
        }

        /* Broadcast our credentials to the process and other LWPs. */
        proc_crmod_leave(ncred, cred, true);
        return 0;
}

int
kauth_cred_getgroups(kauth_cred_t cred, gid_t *grbuf, size_t len,
    enum uio_seg seg)
{
        KASSERT(cred != NULL);

        if (len > cred->cr_ngroups)
                return EINVAL;

        if (seg == UIO_USERSPACE)
                return copyout(cred->cr_groups, grbuf, sizeof(*grbuf) * len);
        memcpy(grbuf, cred->cr_groups, sizeof(*grbuf) * len);

        return 0;
}

int
kauth_register_key(const char *secmodel, kauth_key_t *result)
{
        kauth_key_t k;
        specificdata_key_t key;
        int error;

        KASSERT(result != NULL);

        error = specificdata_key_create(kauth_domain, &key, NULL);
        if (error)
                return (error);

        k = kmem_alloc(sizeof(*k), KM_SLEEP);
        k->ks_secmodel = secmodel;
        k->ks_key = key;

        *result = k;

        return (0);
}

int
kauth_deregister_key(kauth_key_t key)
{
        KASSERT(key != NULL);

        specificdata_key_delete(kauth_domain, key->ks_key);
        kmem_free(key, sizeof(*key));

        return (0);
}

void *
kauth_cred_getdata(kauth_cred_t cred, kauth_key_t key)
{
        KASSERT(cred != NULL);
        KASSERT(key != NULL);

        return (specificdata_getspecific(kauth_domain, &cred->cr_sd,
            key->ks_key));
}

void
kauth_cred_setdata(kauth_cred_t cred, kauth_key_t key, void *data)
{
        KASSERT(cred != NULL);
        KASSERT(key != NULL);

        specificdata_setspecific(kauth_domain, &cred->cr_sd, key->ks_key, data);
}

/*
 * Match uids in two credentials.
 */
int
kauth_cred_uidmatch(kauth_cred_t cred1, kauth_cred_t cred2)
{
        KASSERT(cred1 != NULL);
        KASSERT(cred2 != NULL);

        if (cred1->cr_uid == cred2->cr_uid ||
            cred1->cr_euid == cred2->cr_uid ||
            cred1->cr_uid == cred2->cr_euid ||
            cred1->cr_euid == cred2->cr_euid)
                return (1);

        return (0);
}

u_int
kauth_cred_getrefcnt(kauth_cred_t cred)
{
        KASSERT(cred != NULL);

        return (cred->cr_refcnt);
}

/*
 * Convert userland credentials (struct uucred) to kauth_cred_t.
 * XXX: For NFS & puffs
 */
void    
kauth_uucred_to_cred(kauth_cred_t cred, const struct uucred *uuc)
{       
        KASSERT(cred != NULL);
        KASSERT(uuc != NULL);
 
        cred->cr_refcnt = 1;
        cred->cr_uid = uuc->cr_uid;
        cred->cr_euid = uuc->cr_uid;
        cred->cr_svuid = uuc->cr_uid;
        cred->cr_gid = uuc->cr_gid;
        cred->cr_egid = uuc->cr_gid;
        cred->cr_svgid = uuc->cr_gid;
        cred->cr_ngroups = min(uuc->cr_ngroups, NGROUPS);
        kauth_cred_setgroups(cred, __UNCONST(uuc->cr_groups),
            cred->cr_ngroups, -1, UIO_SYSSPACE);
}

/*
 * Convert kauth_cred_t to userland credentials (struct uucred).
 * XXX: For NFS & puffs
 */
void    
kauth_cred_to_uucred(struct uucred *uuc, const kauth_cred_t cred)
{       
        KASSERT(cred != NULL);
        KASSERT(uuc != NULL);
        int ng;

        ng = min(cred->cr_ngroups, NGROUPS);
        uuc->cr_uid = cred->cr_euid;  
        uuc->cr_gid = cred->cr_egid;  
        uuc->cr_ngroups = ng;
        kauth_cred_getgroups(cred, uuc->cr_groups, ng, UIO_SYSSPACE);
}

/*
 * Compare kauth_cred_t and uucred credentials.
 * XXX: Modelled after crcmp() for NFS.
 */
int
kauth_cred_uucmp(kauth_cred_t cred, const struct uucred *uuc)
{
        KASSERT(cred != NULL);
        KASSERT(uuc != NULL);

        if (cred->cr_euid == uuc->cr_uid &&
            cred->cr_egid == uuc->cr_gid &&
            cred->cr_ngroups == (uint32_t)uuc->cr_ngroups) {
                int i;

                /* Check if all groups from uuc appear in cred. */
                for (i = 0; i < uuc->cr_ngroups; i++) {
                        int ismember;

                        ismember = 0;
                        if (kauth_cred_ismember_gid(cred, uuc->cr_groups[i],
                            &ismember) != 0 || !ismember)
                                return (1);
                }

                return (0);
        }

        return (1);
}

/*
 * Make a struct ucred out of a kauth_cred_t.  For compatibility.
 */
void
kauth_cred_toucred(kauth_cred_t cred, struct ki_ucred *uc)
{
        KASSERT(cred != NULL);
        KASSERT(uc != NULL);

        uc->cr_ref = cred->cr_refcnt;
        uc->cr_uid = cred->cr_euid;
        uc->cr_gid = cred->cr_egid;
        uc->cr_ngroups = min(cred->cr_ngroups, __arraycount(uc->cr_groups));
        memcpy(uc->cr_groups, cred->cr_groups,
               uc->cr_ngroups * sizeof(uc->cr_groups[0]));
}

/*
 * Make a struct pcred out of a kauth_cred_t.  For compatibility.
 */
void
kauth_cred_topcred(kauth_cred_t cred, struct ki_pcred *pc)
{
        KASSERT(cred != NULL);
        KASSERT(pc != NULL);

        pc->p_pad = NULL;
        pc->p_ruid = cred->cr_uid;
        pc->p_svuid = cred->cr_svuid;
        pc->p_rgid = cred->cr_gid;
        pc->p_svgid = cred->cr_svgid;
        pc->p_refcnt = cred->cr_refcnt;
}

/*
 * Return kauth_cred_t for the current LWP.
 */
kauth_cred_t
kauth_cred_get(void)
{
        return (curlwp->l_cred);
}

/*
 * Returns a scope matching the provided id.
 * Requires the scope list lock to be held by the caller.
 */
static kauth_scope_t
kauth_ifindscope(const char *id)
{
        kauth_scope_t scope;

        KASSERT(rw_lock_held(&kauth_lock));

        scope = NULL;
        SIMPLEQ_FOREACH(scope, &scope_list, next_scope) {
                if (strcmp(scope->id, id) == 0)
                        break;
        }

        return (scope);
}

/*
 * Register a new scope.
 *
 * id - identifier for the scope
 * callback - the scope's default listener
 * cookie - cookie to be passed to the listener(s)
 */
kauth_scope_t
kauth_register_scope(const char *id, kauth_scope_callback_t callback,
    void *cookie)
{
        kauth_scope_t scope;
        kauth_listener_t listener = NULL; /* XXX gcc */

        /* Sanitize input */
        if (id == NULL)
                return (NULL);

        /* Allocate space for a new scope and listener. */
        scope = kmem_alloc(sizeof(*scope), KM_SLEEP);
        if (scope == NULL)
                return NULL;
        if (callback != NULL) {
                listener = kmem_alloc(sizeof(*listener), KM_SLEEP);
                if (listener == NULL) {
                        kmem_free(scope, sizeof(*scope));
                        return (NULL);
                }
        }

        /*
         * Acquire scope list lock.
         */
        rw_enter(&kauth_lock, RW_WRITER);

        /* Check we don't already have a scope with the same id */
        if (kauth_ifindscope(id) != NULL) {
                rw_exit(&kauth_lock);

                kmem_free(scope, sizeof(*scope));
                if (callback != NULL)
                        kmem_free(listener, sizeof(*listener));

                return (NULL);
        }

        /* Initialize new scope with parameters */
        scope->id = id;
        scope->cookie = cookie;
        scope->nlisteners = 1;

        SIMPLEQ_INIT(&scope->listenq);

        /* Add default listener */
        if (callback != NULL) {
                listener->func = callback;
                listener->scope = scope;
                listener->refcnt = 0;
                SIMPLEQ_INSERT_HEAD(&scope->listenq, listener, listener_next);
        }

        /* Insert scope to scopes list */
        SIMPLEQ_INSERT_TAIL(&scope_list, scope, next_scope);

        rw_exit(&kauth_lock);

        return (scope);
}

/*
 * Initialize the kernel authorization subsystem.
 *
 * Initialize the scopes list lock.
 * Create specificdata domain.
 * Register the credentials scope, used in kauth(9) internally.
 * Register built-in scopes: generic, system, process, network, machdep, device.
 */
void
kauth_init(void)
{
        rw_init(&kauth_lock);

        kauth_cred_cache = pool_cache_init(sizeof(struct kauth_cred),
            coherency_unit, 0, 0, "kcredpl", NULL, IPL_NONE,
            NULL, NULL, NULL);

        /* Create specificdata domain. */
        kauth_domain = specificdata_domain_create();

        /* Register credentials scope. */
        kauth_builtin_scope_cred =
            kauth_register_scope(KAUTH_SCOPE_CRED, NULL, NULL);

        /* Register generic scope. */
        kauth_builtin_scope_generic = kauth_register_scope(KAUTH_SCOPE_GENERIC,
            NULL, NULL);

        /* Register system scope. */
        kauth_builtin_scope_system = kauth_register_scope(KAUTH_SCOPE_SYSTEM,
            NULL, NULL);

        /* Register process scope. */
        kauth_builtin_scope_process = kauth_register_scope(KAUTH_SCOPE_PROCESS,
            NULL, NULL);

        /* Register network scope. */
        kauth_builtin_scope_network = kauth_register_scope(KAUTH_SCOPE_NETWORK,
            NULL, NULL);

        /* Register machdep scope. */
        kauth_builtin_scope_machdep = kauth_register_scope(KAUTH_SCOPE_MACHDEP,
            NULL, NULL);

        /* Register device scope. */
        kauth_builtin_scope_device = kauth_register_scope(KAUTH_SCOPE_DEVICE,
            NULL, NULL);

        /* Register vnode scope. */
        kauth_builtin_scope_vnode = kauth_register_scope(KAUTH_SCOPE_VNODE,
            NULL, NULL);
}

/*
 * Deregister a scope.
 * Requires scope list lock to be held by the caller.
 *
 * scope - the scope to deregister
 */
void
kauth_deregister_scope(kauth_scope_t scope)
{
        if (scope != NULL) {
                /* Remove scope from list */
                SIMPLEQ_REMOVE(&scope_list, scope, kauth_scope, next_scope);
                kmem_free(scope, sizeof(*scope));
        }
}

/*
 * Register a listener.
 *
 * id - scope identifier.
 * callback - the callback routine for the listener.
 * cookie - cookie to pass unmoidfied to the callback.
 */
kauth_listener_t
kauth_listen_scope(const char *id, kauth_scope_callback_t callback,
   void *cookie)
{
        kauth_scope_t scope;
        kauth_listener_t listener;

        listener = kmem_alloc(sizeof(*listener), KM_SLEEP);
        if (listener == NULL)
                return (NULL);

        rw_enter(&kauth_lock, RW_WRITER);

        /*
         * Find scope struct.
         */
        scope = kauth_ifindscope(id);
        if (scope == NULL) {
                rw_exit(&kauth_lock);
                kmem_free(listener, sizeof(*listener));
                return (NULL);
        }

        /* Allocate listener */

        /* Initialize listener with parameters */
        listener->func = callback;
        listener->refcnt = 0;

        /* Add listener to scope */
        SIMPLEQ_INSERT_TAIL(&scope->listenq, listener, listener_next);

        /* Raise number of listeners on scope. */
        scope->nlisteners++;
        listener->scope = scope;

        rw_exit(&kauth_lock);

        return (listener);
}

/*
 * Deregister a listener.
 *
 * listener - listener reference as returned from kauth_listen_scope().
 */
void
kauth_unlisten_scope(kauth_listener_t listener)
{

        if (listener != NULL) {
                rw_enter(&kauth_lock, RW_WRITER);
                SIMPLEQ_REMOVE(&listener->scope->listenq, listener,
                    kauth_listener, listener_next);
                listener->scope->nlisteners--;
                rw_exit(&kauth_lock);
                kmem_free(listener, sizeof(*listener));
        }
}

/*
 * Authorize a request.
 *
 * scope - the scope of the request as defined by KAUTH_SCOPE_* or as
 *         returned from kauth_register_scope().
 * credential - credentials of the user ("actor") making the request.
 * action - request identifier.
 * arg[0-3] - passed unmodified to listener(s).
 *
 * Returns the aggregated result:
 *     - KAUTH_RESULT_ALLOW if there is at least one KAUTH_RESULT_ALLOW and
 *       zero KAUTH_DESULT_DENY
 *     - KAUTH_RESULT_DENY if there is at least one KAUTH_RESULT_DENY
 *     - KAUTH_RESULT_DEFER if there is nothing but KAUTH_RESULT_DEFER
 */
static int
kauth_authorize_action_internal(kauth_scope_t scope, kauth_cred_t cred,
    kauth_action_t action, void *arg0, void *arg1, void *arg2, void *arg3)
{
        kauth_listener_t listener;
        int error, allow, fail;

        KASSERT(cred != NULL);
        KASSERT(action != 0);

        /* Short-circuit requests coming from the kernel. */
        if (cred == NOCRED || cred == FSCRED)
                return (0);

        KASSERT(scope != NULL);

        fail = 0;
        allow = 0;

        /* rw_enter(&kauth_lock, RW_READER); XXX not yet */
        SIMPLEQ_FOREACH(listener, &scope->listenq, listener_next) {
                error = listener->func(cred, action, scope->cookie, arg0,
                    arg1, arg2, arg3);

                if (error == KAUTH_RESULT_ALLOW)
                        allow = 1;
                else if (error == KAUTH_RESULT_DENY)
                        fail = 1;
        }
        /* rw_exit(&kauth_lock); */

        if (fail)
                return (KAUTH_RESULT_DENY);

        if (allow)
                return (KAUTH_RESULT_ALLOW);

        return (KAUTH_RESULT_DEFER);
};

int
kauth_authorize_action(kauth_scope_t scope, kauth_cred_t cred,
    kauth_action_t action, void *arg0, void *arg1, void *arg2, void *arg3)
{
        int r;

        r = kauth_authorize_action_internal(scope, cred, action, arg0, arg1,
            arg2, arg3);

        if (r == KAUTH_RESULT_DENY)
                return (EPERM);

        if (r == KAUTH_RESULT_ALLOW)
                return (0);

        if (!nsecmodels)
                return (0);

        return (EPERM);
}

/*
 * Generic scope authorization wrapper.
 */
int
kauth_authorize_generic(kauth_cred_t cred, kauth_action_t action, void *arg0)
{
        return (kauth_authorize_action(kauth_builtin_scope_generic, cred, 
            action, arg0, NULL, NULL, NULL));
}

/*
 * System scope authorization wrapper.
 */
int
kauth_authorize_system(kauth_cred_t cred, kauth_action_t action,
    enum kauth_system_req req, void *arg1, void *arg2, void *arg3)
{
        return (kauth_authorize_action(kauth_builtin_scope_system, cred,
            action, (void *)req, arg1, arg2, arg3));
}

/*
 * Process scope authorization wrapper.
 */
int
kauth_authorize_process(kauth_cred_t cred, kauth_action_t action,
    struct proc *p, void *arg1, void *arg2, void *arg3)
{
        return (kauth_authorize_action(kauth_builtin_scope_process, cred,
            action, p, arg1, arg2, arg3));
}

/*
 * Network scope authorization wrapper.
 */
int
kauth_authorize_network(kauth_cred_t cred, kauth_action_t action,
    enum kauth_network_req req, void *arg1, void *arg2, void *arg3)
{
        return (kauth_authorize_action(kauth_builtin_scope_network, cred,
            action, (void *)req, arg1, arg2, arg3));
}

int
kauth_authorize_machdep(kauth_cred_t cred, kauth_action_t action,
    void *arg0, void *arg1, void *arg2, void *arg3)
{
        return (kauth_authorize_action(kauth_builtin_scope_machdep, cred,
            action, arg0, arg1, arg2, arg3));
}

int
kauth_authorize_device(kauth_cred_t cred, kauth_action_t action,
    void *arg0, void *arg1, void *arg2, void *arg3)
{
        return (kauth_authorize_action(kauth_builtin_scope_device, cred,
            action, arg0, arg1, arg2, arg3));
}

int
kauth_authorize_device_tty(kauth_cred_t cred, kauth_action_t action,
    struct tty *tty)
{
        return (kauth_authorize_action(kauth_builtin_scope_device, cred,
            action, tty, NULL, NULL, NULL));
}

int
kauth_authorize_device_spec(kauth_cred_t cred, enum kauth_device_req req,
    struct vnode *vp)
{
        return (kauth_authorize_action(kauth_builtin_scope_device, cred,
            KAUTH_DEVICE_RAWIO_SPEC, (void *)req, vp, NULL, NULL));
}

int
kauth_authorize_device_passthru(kauth_cred_t cred, dev_t dev, u_long bits,
    void *data)
{
        return (kauth_authorize_action(kauth_builtin_scope_device, cred,
            KAUTH_DEVICE_RAWIO_PASSTHRU, (void *)bits, (void *)(u_long)dev,
            data, NULL));
}

kauth_action_t
kauth_mode_to_action(mode_t mode)
{
        kauth_action_t action = 0;

        if (mode & VREAD)
                action |= KAUTH_VNODE_READ_DATA;
        if (mode & VWRITE)
                action |= KAUTH_VNODE_WRITE_DATA;
        if (mode & VEXEC)
                action |= KAUTH_VNODE_EXECUTE;

        return action;
}

int
kauth_authorize_vnode(kauth_cred_t cred, kauth_action_t action,
    struct vnode *vp, struct vnode *dvp, int fs_decision)
{
        int error;

        error = kauth_authorize_action_internal(kauth_builtin_scope_vnode, cred,
            action, vp, dvp, NULL, NULL);

        if (error == KAUTH_RESULT_DENY)
                return (EACCES);

        if (error == KAUTH_RESULT_ALLOW)
                return (0);

        /*
         * If the file-system does not support decision-before-action, we can
         * only short-circuit the operation (deny). If we're here, it means no
         * listener denied it, so our only alternative is to supposedly-allow
         * it and let the file-system have the last word.
         */
        if (fs_decision == KAUTH_VNODE_REMOTEFS)
                return (0);

        return (fs_decision);
}

static int
kauth_cred_hook(kauth_cred_t cred, kauth_action_t action, void *arg0,
    void *arg1)
{
        int r;

        r = kauth_authorize_action(kauth_builtin_scope_cred, cred, action,
            arg0, arg1, NULL, NULL);

#ifdef DIAGNOSTIC
        if (!SIMPLEQ_EMPTY(&kauth_builtin_scope_cred->listenq))
                KASSERT(r == 0);
#endif /* DIAGNOSTIC */

        return (r);
}

void
secmodel_register(void)
{
        KASSERT(nsecmodels + 1 != 0);

        rw_enter(&kauth_lock, RW_WRITER);
        nsecmodels++;
        rw_exit(&kauth_lock);
}

void
secmodel_deregister(void)
{
        KASSERT(nsecmodels != 0);

        rw_enter(&kauth_lock, RW_WRITER);
        nsecmodels--;
        rw_exit(&kauth_lock);
}