/*      $NetBSD: auth_unix.c,v 1.18 2000/07/06 03:03:30 christos Exp $  */

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 2009, Sun Microsystems, 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:
 * - Redistributions of source code must retain the above copyright notice, 
 *   this list of conditions and the following disclaimer.
 * - 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.
 * - Neither the name of Sun Microsystems, Inc. nor the names of its 
 *   contributors may be used to endorse or promote products derived 
 *   from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
 */

#include <sys/cdefs.h>
/*
 * auth_unix.c, Implements UNIX style authentication parameters.
 *
 * Copyright (C) 1984, Sun Microsystems, Inc.
 *
 * The system is very weak.  The client uses no encryption for it's
 * credentials and only sends null verifiers.  The server sends backs
 * null verifiers or optionally a verifier that suggests a new short hand
 * for the credentials.
 *
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/hash.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/pcpu.h>
#include <sys/refcount.h>
#include <sys/sx.h>
#include <sys/ucred.h>

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

#include <rpc/rpc_com.h>

/* auth_unix.c */
static void authunix_nextverf (AUTH *);
static bool_t authunix_marshal (AUTH *, uint32_t, XDR *, struct mbuf *);
static bool_t authunix_validate (AUTH *, uint32_t, struct opaque_auth *,
    struct mbuf **);
static bool_t authunix_refresh (AUTH *, void *);
static void authunix_destroy (AUTH *);
static void marshal_new_auth (AUTH *);

static const struct auth_ops authunix_ops = {
        .ah_nextverf =          authunix_nextverf,
        .ah_marshal =           authunix_marshal,
        .ah_validate =          authunix_validate,
        .ah_refresh =           authunix_refresh,
        .ah_destroy =           authunix_destroy,
};

/*
 * This struct is pointed to by the ah_private field of an auth_handle.
 */
struct audata {
        TAILQ_ENTRY(audata)     au_link;
        TAILQ_ENTRY(audata)     au_alllink;
        volatile u_int          au_refs;
        struct xucred           au_xcred;
        struct opaque_auth      au_origcred;    /* original credentials */
        struct opaque_auth      au_shcred;      /* short hand cred */
        u_long                  au_shfaults;    /* short hand cache faults */
        char                    au_marshed[MAX_AUTH_BYTES];
        u_int                   au_mpos;        /* xdr pos at end of marshed */
        AUTH                    *au_auth;       /* link back to AUTH */
};
TAILQ_HEAD(audata_list, audata);
#define AUTH_PRIVATE(auth)      ((struct audata *)auth->ah_private)

#define AUTH_UNIX_HASH_SIZE     16
#define AUTH_UNIX_MAX           256
static struct audata_list auth_unix_cache[AUTH_UNIX_HASH_SIZE];
static struct audata_list auth_unix_all;
static struct sx auth_unix_lock;
static int auth_unix_count;

static void
authunix_init(void *dummy)
{
        int i;

        for (i = 0; i < AUTH_UNIX_HASH_SIZE; i++)
                TAILQ_INIT(&auth_unix_cache[i]);
        TAILQ_INIT(&auth_unix_all);
        sx_init(&auth_unix_lock, "auth_unix_lock");
}
SYSINIT(authunix_init, SI_SUB_KMEM, SI_ORDER_ANY, authunix_init, NULL);

/*
 * Create a unix style authenticator.
 * Returns an auth handle with the given stuff in it.
 */
AUTH *
authunix_create(struct ucred *cred)
{
        uint32_t h, th;
        struct xucred xcr;
        char mymem[MAX_AUTH_BYTES];
        XDR xdrs;
        AUTH *auth;
        struct audata *au, *tau;
        struct timeval now;
        uint32_t time;
        int len;

        if (auth_unix_count > AUTH_UNIX_MAX) {
                while (auth_unix_count > AUTH_UNIX_MAX) {
                        sx_xlock(&auth_unix_lock);
                        tau = TAILQ_FIRST(&auth_unix_all);
                        th = HASHSTEP(HASHINIT, tau->au_xcred.cr_uid)
                                % AUTH_UNIX_HASH_SIZE;
                        TAILQ_REMOVE(&auth_unix_cache[th], tau, au_link);
                        TAILQ_REMOVE(&auth_unix_all, tau, au_alllink);
                        auth_unix_count--;
                        sx_xunlock(&auth_unix_lock);
                        AUTH_DESTROY(tau->au_auth);
                }
        }

        /*
         * Hash the uid to see if we already have an AUTH with this cred.
         */
        h = HASHSTEP(HASHINIT, cred->cr_uid) % AUTH_UNIX_HASH_SIZE;
        cru2x(cred, &xcr);
again:
        sx_slock(&auth_unix_lock);
        TAILQ_FOREACH(au, &auth_unix_cache[h], au_link) {
                if (!memcmp(&xcr, &au->au_xcred, sizeof(xcr))) {
                        refcount_acquire(&au->au_refs);
                        if (sx_try_upgrade(&auth_unix_lock)) {
                                /*
                                 * Keep auth_unix_all LRU sorted.
                                 */
                                TAILQ_REMOVE(&auth_unix_all, au, au_alllink);
                                TAILQ_INSERT_TAIL(&auth_unix_all, au,
                                    au_alllink);
                                sx_xunlock(&auth_unix_lock);
                        } else {
                                sx_sunlock(&auth_unix_lock);
                        }
                        return (au->au_auth);
                }
        }

        sx_sunlock(&auth_unix_lock);

        /*
         * Allocate and set up auth handle
         */
        au = NULL;
        auth = mem_alloc(sizeof(*auth));
        au = mem_alloc(sizeof(*au));
        auth->ah_ops = &authunix_ops;
        auth->ah_private = (caddr_t)au;
        auth->ah_verf = au->au_shcred = _null_auth;
        refcount_init(&au->au_refs, 1);
        au->au_xcred = xcr;
        au->au_shfaults = 0;
        au->au_origcred.oa_base = NULL;
        au->au_auth = auth;

        getmicrotime(&now);
        time = now.tv_sec;

        /*
         * Serialize the parameters into origcred
         */
        xdrmem_create(&xdrs, mymem, MAX_AUTH_BYTES, XDR_ENCODE);
        cru2x(cred, &xcr);
        if (! xdr_authunix_parms(&xdrs, &time, &xcr)) 
                panic("authunix_create: failed to encode creds");
        au->au_origcred.oa_length = len = XDR_GETPOS(&xdrs);
        au->au_origcred.oa_flavor = AUTH_UNIX;
        au->au_origcred.oa_base = mem_alloc((u_int) len);
        memcpy(au->au_origcred.oa_base, mymem, (size_t)len);

        /*
         * set auth handle to reflect new cred.
         */
        auth->ah_cred = au->au_origcred;
        marshal_new_auth(auth);

        sx_xlock(&auth_unix_lock);
        TAILQ_FOREACH(tau, &auth_unix_cache[h], au_link) {
                if (!memcmp(&xcr, &tau->au_xcred, sizeof(xcr))) {
                        /*
                         * We lost a race to create the AUTH that
                         * matches this cred.
                         */
                        sx_xunlock(&auth_unix_lock);
                        AUTH_DESTROY(auth);
                        goto again;
                }
        }

        auth_unix_count++;
        TAILQ_INSERT_TAIL(&auth_unix_cache[h], au, au_link);
        TAILQ_INSERT_TAIL(&auth_unix_all, au, au_alllink);
        refcount_acquire(&au->au_refs); /* one for the cache, one for user */
        sx_xunlock(&auth_unix_lock);

        return (auth);
}

/*
 * authunix operations
 */

/* ARGSUSED */
static void
authunix_nextverf(AUTH *auth)
{
        /* no action necessary */
}

static bool_t
authunix_marshal(AUTH *auth, uint32_t xid, XDR *xdrs, struct mbuf *args)
{
        struct audata *au;

        au = AUTH_PRIVATE(auth);
        if (!XDR_PUTBYTES(xdrs, au->au_marshed, au->au_mpos))
                return (FALSE);

        return (xdr_putmbuf(xdrs, args));
}

static bool_t
authunix_validate(AUTH *auth, uint32_t xid, struct opaque_auth *verf,
    struct mbuf **mrepp)
{
        struct audata *au;
        XDR txdrs;

        if (!verf)
                return (TRUE);

        if (verf->oa_flavor == AUTH_SHORT) {
                au = AUTH_PRIVATE(auth);
                xdrmem_create(&txdrs, verf->oa_base, verf->oa_length,
                    XDR_DECODE);

                if (au->au_shcred.oa_base != NULL) {
                        mem_free(au->au_shcred.oa_base,
                            au->au_shcred.oa_length);
                        au->au_shcred.oa_base = NULL;
                }
                if (xdr_opaque_auth(&txdrs, &au->au_shcred)) {
                        auth->ah_cred = au->au_shcred;
                } else {
                        txdrs.x_op = XDR_FREE;
                        (void)xdr_opaque_auth(&txdrs, &au->au_shcred);
                        au->au_shcred.oa_base = NULL;
                        auth->ah_cred = au->au_origcred;
                }
                marshal_new_auth(auth);
        }

        return (TRUE);
}

static bool_t
authunix_refresh(AUTH *auth, void *dummy)
{
        struct audata *au = AUTH_PRIVATE(auth);
        struct xucred xcr;
        uint32_t time;
        struct timeval now;
        XDR xdrs;
        int stat;

        if (auth->ah_cred.oa_base == au->au_origcred.oa_base) {
                /* there is no hope.  Punt */
                return (FALSE);
        }
        au->au_shfaults ++;

        /* first deserialize the creds back into a struct ucred */
        xdrmem_create(&xdrs, au->au_origcred.oa_base,
            au->au_origcred.oa_length, XDR_DECODE);
        stat = xdr_authunix_parms(&xdrs, &time, &xcr);
        if (! stat)
                goto done;

        /* update the time and serialize in place */
        getmicrotime(&now);
        time = now.tv_sec;
        xdrs.x_op = XDR_ENCODE;
        XDR_SETPOS(&xdrs, 0);

        stat = xdr_authunix_parms(&xdrs, &time, &xcr);
        if (! stat)
                goto done;
        auth->ah_cred = au->au_origcred;
        marshal_new_auth(auth);
done:
        XDR_DESTROY(&xdrs);
        return (stat);
}

static void
authunix_destroy(AUTH *auth)
{
        struct audata *au;

        au = AUTH_PRIVATE(auth);

        if (!refcount_release(&au->au_refs))
                return;

        mem_free(au->au_origcred.oa_base, au->au_origcred.oa_length);

        if (au->au_shcred.oa_base != NULL)
                mem_free(au->au_shcred.oa_base, au->au_shcred.oa_length);

        mem_free(auth->ah_private, sizeof(struct audata));

        if (auth->ah_verf.oa_base != NULL)
                mem_free(auth->ah_verf.oa_base, auth->ah_verf.oa_length);

        mem_free(auth, sizeof(*auth));
}

/*
 * Marshals (pre-serializes) an auth struct.
 * sets private data, au_marshed and au_mpos
 */
static void
marshal_new_auth(AUTH *auth)
{
        XDR     xdr_stream;
        XDR     *xdrs = &xdr_stream;
        struct audata *au;

        au = AUTH_PRIVATE(auth);
        xdrmem_create(xdrs, au->au_marshed, MAX_AUTH_BYTES, XDR_ENCODE);
        if ((! xdr_opaque_auth(xdrs, &(auth->ah_cred))) ||
            (! xdr_opaque_auth(xdrs, &(auth->ah_verf))))
                printf("auth_none.c - Fatal marshalling problem");
        else
                au->au_mpos = XDR_GETPOS(xdrs);
        XDR_DESTROY(xdrs);
}