5296 Support for more than 16 groups with AUTH_SYS

[unleashed.git] / usr / src / uts / common / fs / nfs / nfs_auth.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2014 Nexenta Systems, Inc.  All rights reserved.
 * Copyright (c) 1995, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#include <sys/param.h>
#include <sys/errno.h>
#include <sys/vfs.h>
#include <sys/vnode.h>
#include <sys/cred.h>
#include <sys/cmn_err.h>
#include <sys/systm.h>
#include <sys/kmem.h>
#include <sys/pathname.h>
#include <sys/utsname.h>
#include <sys/debug.h>
#include <sys/door.h>
#include <sys/sdt.h>
#include <sys/thread.h>

#include <rpc/types.h>
#include <rpc/auth.h>
#include <rpc/clnt.h>

#include <nfs/nfs.h>
#include <nfs/export.h>
#include <nfs/nfs_clnt.h>
#include <nfs/auth.h>

#define EQADDR(a1, a2)  \
        (bcmp((char *)(a1)->buf, (char *)(a2)->buf, (a1)->len) == 0 && \
        (a1)->len == (a2)->len)

static struct knetconfig auth_knconf;
static servinfo_t svp;
static clinfo_t ci;

static struct kmem_cache *exi_cache_handle;
static void exi_cache_reclaim(void *);
static void exi_cache_trim(struct exportinfo *exi);

extern pri_t minclsyspri;

int nfsauth_cache_hit;
int nfsauth_cache_miss;
int nfsauth_cache_refresh;
int nfsauth_cache_reclaim;

/*
 * The lifetime of an auth cache entry:
 * ------------------------------------
 *
 * An auth cache entry is created with both the auth_time
 * and auth_freshness times set to the current time.
 *
 * Upon every client access which results in a hit, the
 * auth_time will be updated.
 *
 * If a client access determines that the auth_freshness
 * indicates that the entry is STALE, then it will be
 * refreshed. Note that this will explicitly reset
 * auth_time.
 *
 * When the REFRESH successfully occurs, then the
 * auth_freshness is updated.
 *
 * There are two ways for an entry to leave the cache:
 *
 * 1) Purged by an action on the export (remove or changed)
 * 2) Memory backpressure from the kernel (check against NFSAUTH_CACHE_TRIM)
 *
 * For 2) we check the timeout value against auth_time.
 */

/*
 * Number of seconds until we mark for refresh an auth cache entry.
 */
#define NFSAUTH_CACHE_REFRESH 600

/*
 * Number of idle seconds until we yield to backpressure
 * to trim a cache entry.
 */
#define NFSAUTH_CACHE_TRIM 3600

/*
 * While we could encapuslate the exi_list inside the
 * exi structure, we can't do that for the auth_list.
 * So, to keep things looking clean, we keep them both
 * in these external lists.
 */
typedef struct refreshq_exi_node {
        struct exportinfo       *ren_exi;
        list_t                  ren_authlist;
        list_node_t             ren_node;
} refreshq_exi_node_t;

typedef struct refreshq_auth_node {
        struct auth_cache       *ran_auth;
        list_node_t             ran_node;
} refreshq_auth_node_t;

/*
 * Used to manipulate things on the refreshq_queue.
 * Note that the refresh thread will effectively
 * pop a node off of the queue, at which point it
 * will no longer need to hold the mutex.
 */
static kmutex_t refreshq_lock;
static list_t refreshq_queue;
static kcondvar_t refreshq_cv;

/*
 * A list_t would be overkill. These are auth_cache
 * entries which are no longer linked to an exi.
 * It should be the case that all of their states
 * are NFS_AUTH_INVALID.
 *
 * I.e., the only way to be put on this list is
 * iff their state indicated that they had been placed
 * on the refreshq_queue.
 *
 * Note that while there is no link from the exi or
 * back to the exi, the exi can not go away until
 * these entries are harvested.
 */
static struct auth_cache        *refreshq_dead_entries;

/*
 * If there is ever a problem with loading the
 * module, then nfsauth_fini() needs to be called
 * to remove state. In that event, since the
 * refreshq thread has been started, they need to
 * work together to get rid of state.
 */
typedef enum nfsauth_refreshq_thread_state {
        REFRESHQ_THREAD_RUNNING,
        REFRESHQ_THREAD_FINI_REQ,
        REFRESHQ_THREAD_HALTED
} nfsauth_refreshq_thread_state_t;

nfsauth_refreshq_thread_state_t
refreshq_thread_state = REFRESHQ_THREAD_HALTED;

static void nfsauth_free_node(struct auth_cache *);
static void nfsauth_remove_dead_entry(struct auth_cache *);
static void nfsauth_refresh_thread(void);

/*
 * mountd is a server-side only daemon. This will need to be
 * revisited if the NFS server is ever made zones-aware.
 */
kmutex_t        mountd_lock;
door_handle_t   mountd_dh;

void
mountd_args(uint_t did)
{
        mutex_enter(&mountd_lock);
        if (mountd_dh != NULL)
                door_ki_rele(mountd_dh);
        mountd_dh = door_ki_lookup(did);
        mutex_exit(&mountd_lock);
}

void
nfsauth_init(void)
{
        /*
         * mountd can be restarted by smf(5). We need to make sure
         * the updated door handle will safely make it to mountd_dh
         */
        mutex_init(&mountd_lock, NULL, MUTEX_DEFAULT, NULL);

        mutex_init(&refreshq_lock, NULL, MUTEX_DEFAULT, NULL);
        list_create(&refreshq_queue, sizeof (refreshq_exi_node_t),
            offsetof(refreshq_exi_node_t, ren_node));
        refreshq_dead_entries = NULL;

        cv_init(&refreshq_cv, NULL, CV_DEFAULT, NULL);

        /*
         * Allocate nfsauth cache handle
         */
        exi_cache_handle = kmem_cache_create("exi_cache_handle",
            sizeof (struct auth_cache), 0, NULL, NULL,
            exi_cache_reclaim, NULL, NULL, 0);

        refreshq_thread_state = REFRESHQ_THREAD_RUNNING;
        (void) zthread_create(NULL, 0, nfsauth_refresh_thread,
            NULL, 0, minclsyspri);
}

/*
 * Finalization routine for nfsauth. It is important to call this routine
 * before destroying the exported_lock.
 */
void
nfsauth_fini(void)
{
        refreshq_exi_node_t     *ren;
        refreshq_auth_node_t    *ran;
        struct auth_cache       *p;
        struct auth_cache       *auth_next;

        /*
         * Prevent the refreshq_thread from getting new
         * work.
         */
        mutex_enter(&refreshq_lock);
        if (refreshq_thread_state != REFRESHQ_THREAD_HALTED) {
                refreshq_thread_state = REFRESHQ_THREAD_FINI_REQ;
                cv_broadcast(&refreshq_cv);

                /*
                 * Also, wait for nfsauth_refresh_thread() to exit.
                 */
                while (refreshq_thread_state != REFRESHQ_THREAD_HALTED) {
                        cv_wait(&refreshq_cv, &refreshq_lock);
                }
        }

        /*
         * Walk the exi_list and in turn, walk the
         * auth_lists.
         */
        while ((ren = list_remove_head(&refreshq_queue))) {
                while ((ran = list_remove_head(&ren->ren_authlist))) {
                        kmem_free(ran, sizeof (refreshq_auth_node_t));
                }

                list_destroy(&ren->ren_authlist);
                exi_rele(ren->ren_exi);
                kmem_free(ren, sizeof (refreshq_exi_node_t));
        }

        /*
         * Okay, now that the lists are deleted, we
         * need to see if there are any dead entries
         * to harvest.
         */
        for (p = refreshq_dead_entries; p != NULL; p = auth_next) {
                auth_next = p->auth_next;
                nfsauth_free_node(p);
        }

        mutex_exit(&refreshq_lock);

        list_destroy(&refreshq_queue);

        cv_destroy(&refreshq_cv);
        mutex_destroy(&refreshq_lock);

        mutex_destroy(&mountd_lock);

        /*
         * Deallocate nfsauth cache handle
         */
        kmem_cache_destroy(exi_cache_handle);
}

/*
 * Convert the address in a netbuf to
 * a hash index for the auth_cache table.
 */
static int
hash(struct netbuf *a)
{
        int i, h = 0;

        for (i = 0; i < a->len; i++)
                h ^= a->buf[i];

        return (h & (AUTH_TABLESIZE - 1));
}

/*
 * Mask out the components of an
 * address that do not identify
 * a host. For socket addresses the
 * masking gets rid of the port number.
 */
static void
addrmask(struct netbuf *addr, struct netbuf *mask)
{
        int i;

        for (i = 0; i < addr->len; i++)
                addr->buf[i] &= mask->buf[i];
}

/*
 * nfsauth4_access is used for NFS V4 auth checking. Besides doing
 * the common nfsauth_access(), it will check if the client can
 * have a limited access to this vnode even if the security flavor
 * used does not meet the policy.
 */
int
nfsauth4_access(struct exportinfo *exi, vnode_t *vp, struct svc_req *req,
    cred_t *cr, uid_t *uid, gid_t *gid, uint_t *ngids, gid_t **gids)
{
        int access;

        access = nfsauth_access(exi, req, cr, uid, gid, ngids, gids);

        /*
         * There are cases that the server needs to allow the client
         * to have a limited view.
         *
         * e.g.
         * /export is shared as "sec=sys,rw=dfs-test-4,sec=krb5,rw"
         * /export/home is shared as "sec=sys,rw"
         *
         * When the client mounts /export with sec=sys, the client
         * would get a limited view with RO access on /export to see
         * "home" only because the client is allowed to access
         * /export/home with auth_sys.
         */
        if (access & NFSAUTH_DENIED || access & NFSAUTH_WRONGSEC) {
                /*
                 * Allow ro permission with LIMITED view if there is a
                 * sub-dir exported under vp.
                 */
                if (has_visible(exi, vp))
                        return (NFSAUTH_LIMITED);
        }

        return (access);
}

static void
sys_log(const char *msg)
{
        static time_t   tstamp = 0;
        time_t          now;

        /*
         * msg is shown (at most) once per minute
         */
        now = gethrestime_sec();
        if ((tstamp + 60) < now) {
                tstamp = now;
                cmn_err(CE_WARN, msg);
        }
}

/*
 * Callup to the mountd to get access information in the kernel.
 */
static bool_t
nfsauth_retrieve(struct exportinfo *exi, char *req_netid, int flavor,
    struct netbuf *addr, int *access, uid_t clnt_uid, gid_t clnt_gid,
    uint_t clnt_gids_cnt, const gid_t *clnt_gids, uid_t *srv_uid,
    gid_t *srv_gid, uint_t *srv_gids_cnt, gid_t **srv_gids)
{
        varg_t                    varg = {0};
        nfsauth_res_t             res = {0};
        XDR                       xdrs;
        size_t                    absz;
        caddr_t                   abuf;
        int                       last = 0;
        door_arg_t                da;
        door_info_t               di;
        door_handle_t             dh;
        uint_t                    ntries = 0;

        /*
         * No entry in the cache for this client/flavor
         * so we need to call the nfsauth service in the
         * mount daemon.
         */

        varg.vers = V_PROTO;
        varg.arg_u.arg.cmd = NFSAUTH_ACCESS;
        varg.arg_u.arg.areq.req_client.n_len = addr->len;
        varg.arg_u.arg.areq.req_client.n_bytes = addr->buf;
        varg.arg_u.arg.areq.req_netid = req_netid;
        varg.arg_u.arg.areq.req_path = exi->exi_export.ex_path;
        varg.arg_u.arg.areq.req_flavor = flavor;
        varg.arg_u.arg.areq.req_clnt_uid = clnt_uid;
        varg.arg_u.arg.areq.req_clnt_gid = clnt_gid;
        varg.arg_u.arg.areq.req_clnt_gids.len = clnt_gids_cnt;
        varg.arg_u.arg.areq.req_clnt_gids.val = (gid_t *)clnt_gids;

        DTRACE_PROBE1(nfsserv__func__nfsauth__varg, varg_t *, &varg);

        /*
         * Setup the XDR stream for encoding the arguments. Notice that
         * in addition to the args having variable fields (req_netid and
         * req_path), the argument data structure is itself versioned,
         * so we need to make sure we can size the arguments buffer
         * appropriately to encode all the args. If we can't get sizing
         * info _or_ properly encode the arguments, there's really no
         * point in continuting, so we fail the request.
         */
        if ((absz = xdr_sizeof(xdr_varg, &varg)) == 0) {
                *access = NFSAUTH_DENIED;
                return (FALSE);
        }

        abuf = (caddr_t)kmem_alloc(absz, KM_SLEEP);
        xdrmem_create(&xdrs, abuf, absz, XDR_ENCODE);
        if (!xdr_varg(&xdrs, &varg)) {
                XDR_DESTROY(&xdrs);
                goto fail;
        }
        XDR_DESTROY(&xdrs);

        /*
         * Prepare the door arguments
         *
         * We don't know the size of the message the daemon
         * will pass back to us.  By setting rbuf to NULL,
         * we force the door code to allocate a buf of the
         * appropriate size.  We must set rsize > 0, however,
         * else the door code acts as if no response was
         * expected and doesn't pass the data to us.
         */
        da.data_ptr = (char *)abuf;
        da.data_size = absz;
        da.desc_ptr = NULL;
        da.desc_num = 0;
        da.rbuf = NULL;
        da.rsize = 1;

retry:
        mutex_enter(&mountd_lock);
        dh = mountd_dh;
        if (dh != NULL)
                door_ki_hold(dh);
        mutex_exit(&mountd_lock);

        if (dh == NULL) {
                /*
                 * The rendezvous point has not been established yet!
                 * This could mean that either mountd(1m) has not yet
                 * been started or that _this_ routine nuked the door
                 * handle after receiving an EINTR for a REVOKED door.
                 *
                 * Returning NFSAUTH_DROP will cause the NFS client
                 * to retransmit the request, so let's try to be more
                 * rescillient and attempt for ntries before we bail.
                 */
                if (++ntries % NFSAUTH_DR_TRYCNT) {
                        delay(hz);
                        goto retry;
                }

                kmem_free(abuf, absz);

                sys_log("nfsauth: mountd has not established door");
                *access = NFSAUTH_DROP;
                return (FALSE);
        }

        ntries = 0;

        /*
         * Now that we've got what we need, place the call.
         */
        switch (door_ki_upcall_limited(dh, &da, NULL, SIZE_MAX, 0)) {
        case 0:                         /* Success */
                door_ki_rele(dh);

                if (da.data_ptr == NULL && da.data_size == 0) {
                        /*
                         * The door_return that contained the data
                         * failed! We're here because of the 2nd
                         * door_return (w/o data) such that we can
                         * get control of the thread (and exit
                         * gracefully).
                         */
                        DTRACE_PROBE1(nfsserv__func__nfsauth__door__nil,
                            door_arg_t *, &da);
                        goto fail;
                }

                break;

        case EAGAIN:
                /*
                 * Server out of resources; back off for a bit
                 */
                door_ki_rele(dh);
                delay(hz);
                goto retry;
                /* NOTREACHED */

        case EINTR:
                if (!door_ki_info(dh, &di)) {
                        door_ki_rele(dh);

                        if (di.di_attributes & DOOR_REVOKED) {
                                /*
                                 * The server barfed and revoked
                                 * the (existing) door on us; we
                                 * want to wait to give smf(5) a
                                 * chance to restart mountd(1m)
                                 * and establish a new door handle.
                                 */
                                mutex_enter(&mountd_lock);
                                if (dh == mountd_dh) {
                                        door_ki_rele(mountd_dh);
                                        mountd_dh = NULL;
                                }
                                mutex_exit(&mountd_lock);
                                delay(hz);
                                goto retry;
                        }
                        /*
                         * If the door was _not_ revoked on us,
                         * then more than likely we took an INTR,
                         * so we need to fail the operation.
                         */
                        goto fail;
                }
                /*
                 * The only failure that can occur from getting
                 * the door info is EINVAL, so we let the code
                 * below handle it.
                 */
                /* FALLTHROUGH */

        case EBADF:
        case EINVAL:
        default:
                /*
                 * If we have a stale door handle, give smf a last
                 * chance to start it by sleeping for a little bit.
                 * If we're still hosed, we'll fail the call.
                 *
                 * Since we're going to reacquire the door handle
                 * upon the retry, we opt to sleep for a bit and
                 * _not_ to clear mountd_dh. If mountd restarted
                 * and was able to set mountd_dh, we should see
                 * the new instance; if not, we won't get caught
                 * up in the retry/DELAY loop.
                 */
                door_ki_rele(dh);
                if (!last) {
                        delay(hz);
                        last++;
                        goto retry;
                }
                sys_log("nfsauth: stale mountd door handle");
                goto fail;
        }

        ASSERT(da.rbuf != NULL);

        /*
         * No door errors encountered; setup the XDR stream for decoding
         * the results. If we fail to decode the results, we've got no
         * other recourse than to fail the request.
         */
        xdrmem_create(&xdrs, da.rbuf, da.rsize, XDR_DECODE);
        if (!xdr_nfsauth_res(&xdrs, &res)) {
                xdr_free(xdr_nfsauth_res, (char *)&res);
                XDR_DESTROY(&xdrs);
                kmem_free(da.rbuf, da.rsize);
                goto fail;
        }
        XDR_DESTROY(&xdrs);
        kmem_free(da.rbuf, da.rsize);

        DTRACE_PROBE1(nfsserv__func__nfsauth__results, nfsauth_res_t *, &res);
        switch (res.stat) {
                case NFSAUTH_DR_OKAY:
                        *access = res.ares.auth_perm;
                        *srv_uid = res.ares.auth_srv_uid;
                        *srv_gid = res.ares.auth_srv_gid;
                        *srv_gids_cnt = res.ares.auth_srv_gids.len;
                        *srv_gids = kmem_alloc(*srv_gids_cnt * sizeof (gid_t),
                            KM_SLEEP);
                        bcopy(res.ares.auth_srv_gids.val, *srv_gids,
                            *srv_gids_cnt * sizeof (gid_t));
                        break;

                case NFSAUTH_DR_EFAIL:
                case NFSAUTH_DR_DECERR:
                case NFSAUTH_DR_BADCMD:
                default:
                        xdr_free(xdr_nfsauth_res, (char *)&res);
fail:
                        *access = NFSAUTH_DENIED;
                        kmem_free(abuf, absz);
                        return (FALSE);
                        /* NOTREACHED */
        }

        xdr_free(xdr_nfsauth_res, (char *)&res);
        kmem_free(abuf, absz);

        return (TRUE);
}

static void
nfsauth_refresh_thread(void)
{
        refreshq_exi_node_t     *ren;
        refreshq_auth_node_t    *ran;

        struct exportinfo       *exi;

        int                     access;
        bool_t                  retrieval;

        callb_cpr_t             cprinfo;

        CALLB_CPR_INIT(&cprinfo, &refreshq_lock, callb_generic_cpr,
            "nfsauth_refresh");

        for (;;) {
                mutex_enter(&refreshq_lock);
                if (refreshq_thread_state != REFRESHQ_THREAD_RUNNING) {
                        /* Keep the hold on the lock! */
                        break;
                }

                ren = list_remove_head(&refreshq_queue);
                if (ren == NULL) {
                        CALLB_CPR_SAFE_BEGIN(&cprinfo);
                        cv_wait(&refreshq_cv, &refreshq_lock);
                        CALLB_CPR_SAFE_END(&cprinfo, &refreshq_lock);
                        mutex_exit(&refreshq_lock);
                        continue;
                }
                mutex_exit(&refreshq_lock);

                exi = ren->ren_exi;
                ASSERT(exi != NULL);

                /*
                 * Since the ren was removed from the refreshq_queue above,
                 * this is the only thread aware about the ren existence, so we
                 * have the exclusive ownership of it and we do not need to
                 * protect it by any lock.
                 */
                while ((ran = list_remove_head(&ren->ren_authlist))) {

                        uint_t ngids;
                        gid_t *gids;
                        struct auth_cache *p = ran->ran_auth;

                        ASSERT(p != NULL);
                        kmem_free(ran, sizeof (refreshq_auth_node_t));

                        /*
                         * We are shutting down. No need to refresh
                         * entries which are about to be nuked.
                         *
                         * So just throw them away until we are done
                         * with this exi node...
                         */
                        if (refreshq_thread_state != REFRESHQ_THREAD_RUNNING)
                                continue;

                        mutex_enter(&p->auth_lock);

                        /*
                         * Make sure the state is valid now that
                         * we have the lock. Note that once we
                         * change the state to NFS_AUTH_REFRESHING,
                         * no other thread will be able to work on
                         * this entry.
                         */
                        if (p->auth_state != NFS_AUTH_STALE) {
                                /*
                                 * Once it goes INVALID, it can not
                                 * change state.
                                 */
                                if (p->auth_state == NFS_AUTH_INVALID) {
                                        mutex_exit(&p->auth_lock);
                                        nfsauth_remove_dead_entry(p);
                                } else
                                        mutex_exit(&p->auth_lock);

                                continue;
                        }

                        p->auth_state = NFS_AUTH_REFRESHING;
                        mutex_exit(&p->auth_lock);

                        DTRACE_PROBE2(nfsauth__debug__cache__refresh,
                            struct exportinfo *, exi,
                            struct auth_cache *, p);

                        /*
                         * The first caching of the access rights
                         * is done with the netid pulled out of the
                         * request from the client. All subsequent
                         * users of the cache may or may not have
                         * the same netid. It doesn't matter. So
                         * when we refresh, we simply use the netid
                         * of the request which triggered the
                         * refresh attempt.
                         */
                        ASSERT(p->auth_netid != NULL);

                        retrieval = nfsauth_retrieve(exi, p->auth_netid,
                            p->auth_flavor, &p->auth_addr, &access,
                            p->auth_clnt_uid, p->auth_clnt_gid,
                            p->auth_clnt_ngids, p->auth_clnt_gids,
                            &p->auth_srv_uid, &p->auth_srv_gid, &ngids, &gids);

                        /*
                         * This can only be set in one other place
                         * and the state has to be NFS_AUTH_FRESH.
                         */
                        kmem_free(p->auth_netid, strlen(p->auth_netid) + 1);
                        p->auth_netid = NULL;

                        mutex_enter(&p->auth_lock);
                        if (p->auth_state == NFS_AUTH_INVALID) {
                                mutex_exit(&p->auth_lock);
                                nfsauth_remove_dead_entry(p);
                                if (retrieval == TRUE)
                                        kmem_free(gids, ngids * sizeof (gid_t));
                        } else {
                                /*
                                 * If we got an error, do not reset the
                                 * time. This will cause the next access
                                 * check for the client to reschedule this
                                 * node.
                                 */
                                if (retrieval == TRUE) {
                                        p->auth_access = access;

                                        kmem_free(p->auth_srv_gids,
                                            p->auth_srv_ngids * sizeof (gid_t));
                                        p->auth_srv_ngids = ngids;
                                        p->auth_srv_gids = gids;

                                        p->auth_freshness = gethrestime_sec();
                                }
                                p->auth_state = NFS_AUTH_FRESH;
                                mutex_exit(&p->auth_lock);
                        }
                }

                list_destroy(&ren->ren_authlist);
                exi_rele(ren->ren_exi);
                kmem_free(ren, sizeof (refreshq_exi_node_t));
        }

        refreshq_thread_state = REFRESHQ_THREAD_HALTED;
        cv_broadcast(&refreshq_cv);
        CALLB_CPR_EXIT(&cprinfo);
        zthread_exit();
}

/*
 * Get the access information from the cache or callup to the mountd
 * to get and cache the access information in the kernel.
 */
static int
nfsauth_cache_get(struct exportinfo *exi, struct svc_req *req, int flavor,
    cred_t *cr, uid_t *uid, gid_t *gid, uint_t *ngids, gid_t **gids)
{
        struct netbuf           *taddrmask;
        struct netbuf           addr;
        struct netbuf           *claddr;
        struct auth_cache       **head;
        struct auth_cache       *p;
        struct auth_cache       *prev = NULL;
        int                     access;
        time_t                  refresh;

        refreshq_exi_node_t     *ren;
        refreshq_auth_node_t    *ran;

        uid_t                   tmpuid;
        gid_t                   tmpgid;
        uint_t                  tmpngids;
        gid_t                   *tmpgids;

        ASSERT(cr != NULL);

        /*
         * Now check whether this client already
         * has an entry for this flavor in the cache
         * for this export.
         * Get the caller's address, mask off the
         * parts of the address that do not identify
         * the host (port number, etc), and then hash
         * it to find the chain of cache entries.
         */

        claddr = svc_getrpccaller(req->rq_xprt);
        addr = *claddr;
        addr.buf = kmem_alloc(addr.len, KM_SLEEP);
        bcopy(claddr->buf, addr.buf, claddr->len);
        SVC_GETADDRMASK(req->rq_xprt, SVC_TATTR_ADDRMASK, (void **)&taddrmask);
        ASSERT(taddrmask != NULL);
        if (taddrmask)
                addrmask(&addr, taddrmask);

        rw_enter(&exi->exi_cache_lock, RW_READER);
        head = &exi->exi_cache[hash(&addr)];
        for (p = *head; p; p = p->auth_next) {
                if (EQADDR(&addr, &p->auth_addr) && flavor == p->auth_flavor &&
                    crgetuid(cr) == p->auth_clnt_uid &&
                    crgetgid(cr) == p->auth_clnt_gid)
                        break;
                prev = p;
        }

        if (p != NULL) {
                /*
                 * In a case the client's supplemental groups changed we need
                 * to discard the auth_cache entry and re-retrieve it.
                 */
                mutex_enter(&p->auth_lock);
                if (p->auth_clnt_ngids != crgetngroups(cr) ||
                    bcmp(p->auth_clnt_gids, crgetgroups(cr),
                    p->auth_clnt_ngids * sizeof (gid_t))) {
                        auth_state_t prev_state = p->auth_state;

                        p->auth_state = NFS_AUTH_INVALID;
                        mutex_exit(&p->auth_lock);

                        if (prev_state == NFS_AUTH_FRESH) {
                                if (rw_tryupgrade(&exi->exi_cache_lock) == 0) {
                                        struct auth_cache *tmp;

                                        rw_exit(&exi->exi_cache_lock);
                                        rw_enter(&exi->exi_cache_lock,
                                            RW_WRITER);

                                        prev = NULL;
                                        for (tmp = *head; tmp != NULL;
                                            tmp = tmp->auth_next) {
                                                if (p == tmp)
                                                        break;
                                                prev = p;
                                        }
                                }

                                if (prev == NULL)
                                        exi->exi_cache[hash(&addr)] =
                                            p->auth_next;
                                else
                                        prev->auth_next = p->auth_next;

                                nfsauth_free_node(p);
                        }

                        goto retrieve;
                }
                mutex_exit(&p->auth_lock);

                nfsauth_cache_hit++;

                refresh = gethrestime_sec() - p->auth_freshness;
                DTRACE_PROBE2(nfsauth__debug__cache__hit,
                    int, nfsauth_cache_hit,
                    time_t, refresh);

                mutex_enter(&p->auth_lock);
                if ((refresh > NFSAUTH_CACHE_REFRESH) &&
                    p->auth_state == NFS_AUTH_FRESH) {
                        p->auth_state = NFS_AUTH_STALE;
                        mutex_exit(&p->auth_lock);

                        ASSERT(p->auth_netid == NULL);
                        p->auth_netid =
                            strdup(svc_getnetid(req->rq_xprt));

                        nfsauth_cache_refresh++;

                        DTRACE_PROBE3(nfsauth__debug__cache__stale,
                            struct exportinfo *, exi,
                            struct auth_cache *, p,
                            int, nfsauth_cache_refresh);

                        ran = kmem_alloc(sizeof (refreshq_auth_node_t),
                            KM_SLEEP);
                        ran->ran_auth = p;

                        mutex_enter(&refreshq_lock);
                        /*
                         * We should not add a work queue
                         * item if the thread is not
                         * accepting them.
                         */
                        if (refreshq_thread_state == REFRESHQ_THREAD_RUNNING) {
                                /*
                                 * Is there an existing exi_list?
                                 */
                                for (ren = list_head(&refreshq_queue);
                                    ren != NULL;
                                    ren = list_next(&refreshq_queue, ren)) {
                                        if (ren->ren_exi == exi) {
                                                list_insert_tail(
                                                    &ren->ren_authlist, ran);
                                                break;
                                        }
                                }

                                if (ren == NULL) {
                                        ren = kmem_alloc(
                                            sizeof (refreshq_exi_node_t),
                                            KM_SLEEP);

                                        exi_hold(exi);
                                        ren->ren_exi = exi;

                                        list_create(&ren->ren_authlist,
                                            sizeof (refreshq_auth_node_t),
                                            offsetof(refreshq_auth_node_t,
                                            ran_node));

                                        list_insert_tail(&ren->ren_authlist,
                                            ran);
                                        list_insert_tail(&refreshq_queue, ren);
                                }

                                cv_broadcast(&refreshq_cv);
                        } else {
                                kmem_free(ran, sizeof (refreshq_auth_node_t));
                        }

                        mutex_exit(&refreshq_lock);
                } else {
                        mutex_exit(&p->auth_lock);
                }

                access = p->auth_access;
                if (uid != NULL)
                        *uid = p->auth_srv_uid;
                if (gid != NULL)
                        *gid = p->auth_srv_gid;
                if (ngids != NULL && gids != NULL) {
                        *ngids = p->auth_srv_ngids;
                        *gids = kmem_alloc(*ngids * sizeof (gid_t), KM_SLEEP);
                        bcopy(p->auth_srv_gids, *gids, *ngids * sizeof (gid_t));
                }

                p->auth_time = gethrestime_sec();

                rw_exit(&exi->exi_cache_lock);
                kmem_free(addr.buf, addr.len);

                return (access);
        }

retrieve:
        rw_exit(&exi->exi_cache_lock);

        nfsauth_cache_miss++;

        if (!nfsauth_retrieve(exi, svc_getnetid(req->rq_xprt), flavor,
            &addr, &access, crgetuid(cr), crgetgid(cr), crgetngroups(cr),
            crgetgroups(cr), &tmpuid, &tmpgid, &tmpngids, &tmpgids)) {
                kmem_free(addr.buf, addr.len);
                if (ngids != NULL && gids != NULL) {
                        *ngids = 0;
                        *gids = NULL;
                }
                return (access);
        }

        if (uid != NULL)
                *uid = tmpuid;
        if (gid != NULL)
                *gid = tmpgid;
        if (ngids != NULL && gids != NULL) {
                *ngids = tmpngids;
                *gids = tmpgids;

                /*
                 * We need a copy of gids for the auth_cache entry
                 */
                tmpgids = kmem_alloc(tmpngids * sizeof (gid_t), KM_NOSLEEP);
                if (tmpgids != NULL)
                        bcopy(*gids, tmpgids, tmpngids * sizeof (gid_t));
        }

        /*
         * Now cache the result on the cache chain
         * for this export (if there's enough memory)
         */
        p = kmem_cache_alloc(exi_cache_handle, KM_NOSLEEP);
        if (p != NULL)
                p->auth_clnt_gids = kmem_alloc(
                    crgetngroups(cr) * sizeof (gid_t), KM_NOSLEEP);
        if (p != NULL && (tmpngids == 0 || tmpgids != NULL) &&
            (crgetngroups(cr) == 0 || p->auth_clnt_gids != NULL)) {
                p->auth_addr = addr;
                p->auth_flavor = flavor;
                p->auth_clnt_uid = crgetuid(cr);
                p->auth_clnt_gid = crgetgid(cr);
                p->auth_clnt_ngids = crgetngroups(cr);
                bcopy(crgetgroups(cr), p->auth_clnt_gids,
                    p->auth_clnt_ngids * sizeof (gid_t));
                p->auth_srv_uid = tmpuid;
                p->auth_srv_gid = tmpgid;
                p->auth_srv_ngids = tmpngids;
                p->auth_srv_gids = tmpgids;
                p->auth_access = access;
                p->auth_time = p->auth_freshness = gethrestime_sec();
                p->auth_state = NFS_AUTH_FRESH;
                p->auth_netid = NULL;
                mutex_init(&p->auth_lock, NULL, MUTEX_DEFAULT, NULL);

                rw_enter(&exi->exi_cache_lock, RW_WRITER);
                p->auth_next = *head;
                *head = p;
                rw_exit(&exi->exi_cache_lock);
        } else {
                kmem_free(addr.buf, addr.len);
                if (tmpgids != NULL)
                        kmem_free(tmpgids, tmpngids * sizeof (gid_t));
                if (p != NULL) {
                        if (p->auth_clnt_gids != NULL)
                                kmem_free(p->auth_clnt_gids,
                                    crgetngroups(cr) * sizeof (gid_t));
                        kmem_cache_free(exi_cache_handle, p);
                }
        }

        return (access);
}

/*
 * Check if the requesting client has access to the filesystem with
 * a given nfs flavor number which is an explicitly shared flavor.
 */
int
nfsauth4_secinfo_access(struct exportinfo *exi, struct svc_req *req,
                        int flavor, int perm, cred_t *cr)
{
        int access;

        if (! (perm & M_4SEC_EXPORTED)) {
                return (NFSAUTH_DENIED);
        }

        /*
         * Optimize if there are no lists
         */
        if ((perm & (M_ROOT | M_NONE | M_MAP)) == 0) {
                perm &= ~M_4SEC_EXPORTED;
                if (perm == M_RO)
                        return (NFSAUTH_RO);
                if (perm == M_RW)
                        return (NFSAUTH_RW);
        }

        access = nfsauth_cache_get(exi, req, flavor, cr, NULL, NULL, NULL,
            NULL);

        return (access);
}

int
nfsauth_access(struct exportinfo *exi, struct svc_req *req, cred_t *cr,
    uid_t *uid, gid_t *gid, uint_t *ngids, gid_t **gids)
{
        int access, mapaccess;
        struct secinfo *sp;
        int i, flavor, perm;
        int authnone_entry = -1;

        /*
         *  Get the nfs flavor number from xprt.
         */
        flavor = (int)(uintptr_t)req->rq_xprt->xp_cookie;

        /*
         * First check the access restrictions on the filesystem.  If
         * there are no lists associated with this flavor then there's no
         * need to make an expensive call to the nfsauth service or to
         * cache anything.
         */

        sp = exi->exi_export.ex_secinfo;
        for (i = 0; i < exi->exi_export.ex_seccnt; i++) {
                if (flavor != sp[i].s_secinfo.sc_nfsnum) {
                        if (sp[i].s_secinfo.sc_nfsnum == AUTH_NONE)
                                authnone_entry = i;
                        continue;
                }
                break;
        }

        mapaccess = 0;

        if (i >= exi->exi_export.ex_seccnt) {
                /*
                 * Flavor not found, but use AUTH_NONE if it exists
                 */
                if (authnone_entry == -1)
                        return (NFSAUTH_DENIED);
                flavor = AUTH_NONE;
                mapaccess = NFSAUTH_MAPNONE;
                i = authnone_entry;
        }

        /*
         * By default root is mapped to anonymous user.
         * This might get overriden later in nfsauth_cache_get().
         */
        if (crgetuid(cr) == 0) {
                if (uid != NULL)
                        *uid = exi->exi_export.ex_anon;
                if (gid != NULL)
                        *gid = exi->exi_export.ex_anon;
        } else {
                if (uid != NULL)
                        *uid = crgetuid(cr);
                if (gid != NULL)
                        *gid = crgetgid(cr);
        }

        if (ngids != NULL)
                *ngids = 0;
        if (gids != NULL)
                *gids = NULL;

        /*
         * If the flavor is in the ex_secinfo list, but not an explicitly
         * shared flavor by the user, it is a result of the nfsv4 server
         * namespace setup. We will grant an RO permission similar for
         * a pseudo node except that this node is a shared one.
         *
         * e.g. flavor in (flavor) indicates that it is not explictly
         *      shared by the user:
         *
         *              /       (sys, krb5)
         *              |
         *              export  #share -o sec=sys (krb5)
         *              |
         *              secure  #share -o sec=krb5
         *
         *      In this case, when a krb5 request coming in to access
         *      /export, RO permission is granted.
         */
        if (!(sp[i].s_flags & M_4SEC_EXPORTED))
                return (mapaccess | NFSAUTH_RO);

        /*
         * Optimize if there are no lists.
         * We cannot optimize for AUTH_SYS with NGRPS (16) supplemental groups.
         */
        perm = sp[i].s_flags;
        if ((perm & (M_ROOT | M_NONE | M_MAP)) == 0 && (ngroups_max <= NGRPS ||
            flavor != AUTH_SYS || crgetngroups(cr) < NGRPS)) {
                perm &= ~M_4SEC_EXPORTED;
                if (perm == M_RO)
                        return (mapaccess | NFSAUTH_RO);
                if (perm == M_RW)
                        return (mapaccess | NFSAUTH_RW);
        }

        access = nfsauth_cache_get(exi, req, flavor, cr, uid, gid, ngids, gids);

        /*
         * For both NFSAUTH_DENIED and NFSAUTH_WRONGSEC we do not care about
         * the supplemental groups.
         */
        if (access & NFSAUTH_DENIED || access & NFSAUTH_WRONGSEC) {
                if (ngids != NULL && gids != NULL) {
                        kmem_free(*gids, *ngids * sizeof (gid_t));
                        *ngids = 0;
                        *gids = NULL;
                }
        }

        /*
         * Client's security flavor doesn't match with "ro" or
         * "rw" list. Try again using AUTH_NONE if present.
         */
        if ((access & NFSAUTH_WRONGSEC) && (flavor != AUTH_NONE)) {
                /*
                 * Have we already encountered AUTH_NONE ?
                 */
                if (authnone_entry != -1) {
                        mapaccess = NFSAUTH_MAPNONE;
                        access = nfsauth_cache_get(exi, req, AUTH_NONE, cr,
                            NULL, NULL, NULL, NULL);
                } else {
                        /*
                         * Check for AUTH_NONE presence.
                         */
                        for (; i < exi->exi_export.ex_seccnt; i++) {
                                if (sp[i].s_secinfo.sc_nfsnum == AUTH_NONE) {
                                        mapaccess = NFSAUTH_MAPNONE;
                                        access = nfsauth_cache_get(exi, req,
                                            AUTH_NONE, cr, NULL, NULL, NULL,
                                            NULL);
                                        break;
                                }
                        }
                }
        }

        if (access & NFSAUTH_DENIED)
                access = NFSAUTH_DENIED;

        return (access | mapaccess);
}

static void
nfsauth_free_node(struct auth_cache *p)
{
        if (p->auth_netid != NULL)
                kmem_free(p->auth_netid, strlen(p->auth_netid) + 1);
        kmem_free(p->auth_addr.buf, p->auth_addr.len);
        kmem_free(p->auth_clnt_gids, p->auth_clnt_ngids * sizeof (gid_t));
        kmem_free(p->auth_srv_gids, p->auth_srv_ngids * sizeof (gid_t));
        mutex_destroy(&p->auth_lock);
        kmem_cache_free(exi_cache_handle, p);
}

/*
 * Remove the dead entry from the refreshq_dead_entries
 * list.
 */
static void
nfsauth_remove_dead_entry(struct auth_cache *dead)
{
        struct auth_cache       *p;
        struct auth_cache       *prev;
        struct auth_cache       *next;

        mutex_enter(&refreshq_lock);
        prev = NULL;
        for (p = refreshq_dead_entries; p != NULL; p = next) {
                next = p->auth_next;

                if (p == dead) {
                        if (prev == NULL)
                                refreshq_dead_entries = next;
                        else
                                prev->auth_next = next;

                        nfsauth_free_node(dead);
                        break;
                }

                prev = p;
        }
        mutex_exit(&refreshq_lock);
}

/*
 * Free the nfsauth cache for a given export
 */
void
nfsauth_cache_free(struct exportinfo *exi)
{
        int i;
        struct auth_cache *p, *next;

        for (i = 0; i < AUTH_TABLESIZE; i++) {
                for (p = exi->exi_cache[i]; p; p = next) {
                        next = p->auth_next;

                        /*
                         * The only way we got here
                         * was with an exi_rele, which
                         * means that no auth cache entry
                         * is being refreshed.
                         */
                        nfsauth_free_node(p);
                }
        }
}

/*
 * Called by the kernel memory allocator when
 * memory is low. Free unused cache entries.
 * If that's not enough, the VM system will
 * call again for some more.
 */
/*ARGSUSED*/
void
exi_cache_reclaim(void *cdrarg)
{
        int i;
        struct exportinfo *exi;

        rw_enter(&exported_lock, RW_READER);

        for (i = 0; i < EXPTABLESIZE; i++) {
                for (exi = exptable[i]; exi; exi = exi->fid_hash.next) {
                        exi_cache_trim(exi);
                }
        }
        nfsauth_cache_reclaim++;

        rw_exit(&exported_lock);
}

void
exi_cache_trim(struct exportinfo *exi)
{
        struct auth_cache *p;
        struct auth_cache *prev, *next;
        int i;
        time_t stale_time;

        stale_time = gethrestime_sec() - NFSAUTH_CACHE_TRIM;

        rw_enter(&exi->exi_cache_lock, RW_WRITER);

        for (i = 0; i < AUTH_TABLESIZE; i++) {

                /*
                 * Free entries that have not been
                 * used for NFSAUTH_CACHE_TRIM seconds.
                 */
                prev = NULL;
                for (p = exi->exi_cache[i]; p; p = next) {
                        next = p->auth_next;
                        if (p->auth_time > stale_time) {
                                prev = p;
                                continue;
                        }

                        mutex_enter(&p->auth_lock);
                        DTRACE_PROBE1(nfsauth__debug__trim__state,
                            auth_state_t, p->auth_state);

                        if (p->auth_state != NFS_AUTH_FRESH) {
                                p->auth_state = NFS_AUTH_INVALID;
                                mutex_exit(&p->auth_lock);

                                mutex_enter(&refreshq_lock);
                                p->auth_next = refreshq_dead_entries;
                                refreshq_dead_entries = p;
                                mutex_exit(&refreshq_lock);
                        } else {
                                mutex_exit(&p->auth_lock);
                                nfsauth_free_node(p);
                        }

                        if (prev == NULL)
                                exi->exi_cache[i] = next;
                        else
                                prev->auth_next = next;
                }
        }

        rw_exit(&exi->exi_cache_lock);
}