/*
 * Copyright (c) 1988 by Sun Microsystems, Inc.
 */

/*-
 * 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.
 */

/*
 * svcauth_des.c, server-side des authentication
 *
 * We insure for the service the following:
 * (1) The timestamp microseconds do not exceed 1 million.
 * (2) The timestamp plus the window is less than the current time.
 * (3) The timestamp is not less than the one previously
 *     seen in the current session.
 *
 * It is up to the server to determine if the window size is
 * too small .
 *
 */

#include "namespace.h"
#include "reentrant.h"
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <rpc/des_crypt.h>
#include <sys/param.h>
#include <netinet/in.h>
#include <rpc/types.h>
#include <rpc/xdr.h>
#include <rpc/auth.h>
#include <rpc/auth_des.h>
#include <rpc/svc.h>
#include <rpc/rpc_msg.h>
#include <rpc/svc_auth.h>
#include "libc_private.h"

extern int key_decryptsession_pk(const char *, netobj *, des_block *);

#define debug(msg)       printf("svcauth_des: %s\n", msg) 

#define USEC_PER_SEC ((u_long) 1000000L)
#define BEFORE(t1, t2) timercmp(t1, t2, <)

/*
 * LRU cache of conversation keys and some other useful items.
 */
#define AUTHDES_CACHESZ 64
struct cache_entry {
        des_block key;          /* conversation key */
        char *rname;            /* client's name */
        u_int window;           /* credential lifetime window */
        struct timeval laststamp;       /* detect replays of creds */
        char *localcred;        /* generic local credential */
};
static struct cache_entry *authdes_cache/* [AUTHDES_CACHESZ] */;
static short *authdes_lru/* [AUTHDES_CACHESZ] */;

static void cache_init(void);   /* initialize the cache */
static short cache_spot(des_block *, char *, struct timeval *); /* find an entry in the cache */
static void cache_ref(short sid);       /* note that sid was ref'd */

static void invalidate(char *); /* invalidate entry in cache */

/*
 * cache statistics 
 */
static struct {
        u_long ncachehits;      /* times cache hit, and is not replay */
        u_long ncachereplays;   /* times cache hit, and is replay */
        u_long ncachemisses;    /* times cache missed */
} svcauthdes_stats;

/*
 * Service side authenticator for AUTH_DES
 */
enum auth_stat
_svcauth_des(struct svc_req *rqst, struct rpc_msg *msg)
{

        long *ixdr;
        des_block cryptbuf[2];
        struct authdes_cred *cred;
        struct authdes_verf verf;
        int status;
        struct cache_entry *entry;
        short sid = 0;
        des_block *sessionkey;
        des_block ivec;
        u_int window;
        struct timeval timestamp;
        u_long namelen;
        struct area {
                struct authdes_cred area_cred;
                char area_netname[MAXNETNAMELEN+1];
        } *area;

        if (authdes_cache == NULL) {
                cache_init();
        }

        area = (struct area *)rqst->rq_clntcred;
        cred = (struct authdes_cred *)&area->area_cred;

        /*
         * Get the credential
         */
        ixdr = (long *)msg->rm_call.cb_cred.oa_base;
        cred->adc_namekind = IXDR_GET_ENUM(ixdr, enum authdes_namekind);
        switch (cred->adc_namekind) {
        case ADN_FULLNAME:
                namelen = IXDR_GET_U_LONG(ixdr);
                if (namelen > MAXNETNAMELEN) {
                        return (AUTH_BADCRED);
                }
                cred->adc_fullname.name = area->area_netname;
                bcopy((char *)ixdr, cred->adc_fullname.name, 
                        (u_int)namelen);
                cred->adc_fullname.name[namelen] = 0;
                ixdr += (RNDUP(namelen) / BYTES_PER_XDR_UNIT);
                cred->adc_fullname.key.key.high = (u_long)*ixdr++;
                cred->adc_fullname.key.key.low = (u_long)*ixdr++;
                cred->adc_fullname.window = (u_long)*ixdr++;
                break;
        case ADN_NICKNAME:
                cred->adc_nickname = (u_long)*ixdr++;
                break;
        default:
                return (AUTH_BADCRED);  
        }

        /*
         * Get the verifier
         */
        ixdr = (long *)msg->rm_call.cb_verf.oa_base;
        verf.adv_xtimestamp.key.high = (u_long)*ixdr++;
        verf.adv_xtimestamp.key.low =  (u_long)*ixdr++;
        verf.adv_int_u = (u_long)*ixdr++;


        /*
         * Get the conversation key
         */
        if (cred->adc_namekind == ADN_FULLNAME) {
                netobj pkey;
                char pkey_data[1024];

                sessionkey = &cred->adc_fullname.key;
                if (! getpublickey(cred->adc_fullname.name, pkey_data)) {
                        debug("getpublickey");
                        return(AUTH_BADCRED);
                }
                pkey.n_bytes = pkey_data;
                pkey.n_len = strlen(pkey_data) + 1;
                if (key_decryptsession_pk(cred->adc_fullname.name, &pkey,
                                       sessionkey) < 0) {
                        debug("decryptsessionkey");
                        return (AUTH_BADCRED); /* key not found */
                }
        } else { /* ADN_NICKNAME */     
                sid = (short)cred->adc_nickname;
                if (sid < 0 || sid >= AUTHDES_CACHESZ) {
                        debug("bad nickname");
                        return (AUTH_BADCRED);  /* garbled credential */
                }
                sessionkey = &authdes_cache[sid].key;
        }


        /*
         * Decrypt the timestamp
         */
        cryptbuf[0] = verf.adv_xtimestamp; 
        if (cred->adc_namekind == ADN_FULLNAME) {
                cryptbuf[1].key.high = cred->adc_fullname.window;
                cryptbuf[1].key.low = verf.adv_winverf;
                ivec.key.high = ivec.key.low = 0;       
                status = cbc_crypt((char *)sessionkey, (char *)cryptbuf,
                        2*sizeof(des_block), DES_DECRYPT | DES_HW, 
                        (char *)&ivec);
        } else {
                status = ecb_crypt((char *)sessionkey, (char *)cryptbuf,
                        sizeof(des_block), DES_DECRYPT | DES_HW);
        }
        if (DES_FAILED(status)) {
                debug("decryption failure");
                return (AUTH_FAILED);   /* system error */
        }

        /*
         * XDR the decrypted timestamp
         */
        ixdr = (long *)cryptbuf;
        timestamp.tv_sec = IXDR_GET_LONG(ixdr);
        timestamp.tv_usec = IXDR_GET_LONG(ixdr);

        /*
         * Check for valid credentials and verifiers.
         * They could be invalid because the key was flushed
         * out of the cache, and so a new session should begin.
         * Be sure and send AUTH_REJECTED{CRED, VERF} if this is the case.
         */
        {
                struct timeval current;
                int nick;
                int winverf;

                if (cred->adc_namekind == ADN_FULLNAME) {
                        window = IXDR_GET_U_LONG(ixdr);
                        winverf = IXDR_GET_U_LONG(ixdr);
                        if (winverf != window - 1) {
                                debug("window verifier mismatch");
                                return (AUTH_BADCRED);  /* garbled credential */
                        }
                        sid = cache_spot(sessionkey, cred->adc_fullname.name, 
                            &timestamp);
                        if (sid < 0) {
                                debug("replayed credential");
                                return (AUTH_REJECTEDCRED);     /* replay */
                        }
                        nick = 0;
                } else {        /* ADN_NICKNAME */
                        window = authdes_cache[sid].window;
                        nick = 1;
                }

                if ((u_long)timestamp.tv_usec >= USEC_PER_SEC) {
                        debug("invalid usecs");
                        /* cached out (bad key), or garbled verifier */
                        return (nick ? AUTH_REJECTEDVERF : AUTH_BADVERF);
                }
                if (nick && BEFORE(&timestamp, 
                                   &authdes_cache[sid].laststamp)) {
                        debug("timestamp before last seen");
                        return (AUTH_REJECTEDVERF);     /* replay */
                }
                (void)gettimeofday(&current, NULL);
                current.tv_sec -= window;       /* allow for expiration */
                if (!BEFORE(&current, &timestamp)) {
                        debug("timestamp expired");
                        /* replay, or garbled credential */
                        return (nick ? AUTH_REJECTEDVERF : AUTH_BADCRED);
                }
        }

        /*
         * Set up the reply verifier
         */
        verf.adv_nickname = (u_long)sid;

        /*
         * xdr the timestamp before encrypting
         */
        ixdr = (long *)cryptbuf;
        IXDR_PUT_LONG(ixdr, timestamp.tv_sec - 1);
        IXDR_PUT_LONG(ixdr, timestamp.tv_usec);

        /*       
         * encrypt the timestamp
         */
        status = ecb_crypt((char *)sessionkey, (char *)cryptbuf,
            sizeof(des_block), DES_ENCRYPT | DES_HW);
        if (DES_FAILED(status)) {
                debug("encryption failure");
                return (AUTH_FAILED);   /* system error */
        }
        verf.adv_xtimestamp = cryptbuf[0];

        /*
         * Serialize the reply verifier, and update rqst
         */
        ixdr = (long *)msg->rm_call.cb_verf.oa_base;
        *ixdr++ = (long)verf.adv_xtimestamp.key.high;
        *ixdr++ = (long)verf.adv_xtimestamp.key.low;
        *ixdr++ = (long)verf.adv_int_u;

        rqst->rq_xprt->xp_verf.oa_flavor = AUTH_DES;
        rqst->rq_xprt->xp_verf.oa_base = msg->rm_call.cb_verf.oa_base;
        rqst->rq_xprt->xp_verf.oa_length = 
                (char *)ixdr - msg->rm_call.cb_verf.oa_base;

        /*
         * We succeeded, commit the data to the cache now and
         * finish cooking the credential.
         */
        entry = &authdes_cache[sid];
        entry->laststamp = timestamp;
        cache_ref(sid);
        if (cred->adc_namekind == ADN_FULLNAME) {
                cred->adc_fullname.window = window;
                cred->adc_nickname = (u_long)sid;       /* save nickname */
                if (entry->rname != NULL) {
                        mem_free(entry->rname, strlen(entry->rname) + 1);
                }
                entry->rname = (char *)mem_alloc((u_int)strlen(cred->adc_fullname.name)
                                         + 1);
                if (entry->rname != NULL) {
                        (void) strcpy(entry->rname, cred->adc_fullname.name);
                } else {
                        debug("out of memory");
                }
                entry->key = *sessionkey;
                entry->window = window;
                invalidate(entry->localcred); /* mark any cached cred invalid */
        } else { /* ADN_NICKNAME */
                /*
                 * nicknames are cooked into fullnames
                 */     
                cred->adc_namekind = ADN_FULLNAME;
                cred->adc_fullname.name = entry->rname;
                cred->adc_fullname.key = entry->key;
                cred->adc_fullname.window = entry->window;
        }
        return (AUTH_OK);       /* we made it!*/
}


/*
 * Initialize the cache
 */
static void
cache_init(void)
{
        int i;

        authdes_cache = (struct cache_entry *)
                mem_alloc(sizeof(struct cache_entry) * AUTHDES_CACHESZ);        
        bzero((char *)authdes_cache, 
                sizeof(struct cache_entry) * AUTHDES_CACHESZ);

        authdes_lru = (short *)mem_alloc(sizeof(short) * AUTHDES_CACHESZ);
        /*
         * Initialize the lru list
         */
        for (i = 0; i < AUTHDES_CACHESZ; i++) {
                authdes_lru[i] = i;
        }
}


/*
 * Find the lru victim
 */
static short
cache_victim(void)
{
        return (authdes_lru[AUTHDES_CACHESZ-1]);
}

/*
 * Note that sid was referenced
 */
static void
cache_ref(short sid)
{
        int i;
        short curr;
        short prev;

        prev = authdes_lru[0];
        authdes_lru[0] = sid;
        for (i = 1; prev != sid; i++) {
                curr = authdes_lru[i];
                authdes_lru[i] = prev;
                prev = curr;
        }
}


/*
 * Find a spot in the cache for a credential containing
 * the items given.  Return -1 if a replay is detected, otherwise
 * return the spot in the cache.
 */
static short
cache_spot(des_block *key, char *name, struct timeval *timestamp)
{
        struct cache_entry *cp;
        int i;
        u_long hi;

        hi = key->key.high;
        for (cp = authdes_cache, i = 0; i < AUTHDES_CACHESZ; i++, cp++) {
                if (cp->key.key.high == hi && 
                    cp->key.key.low == key->key.low &&
                    cp->rname != NULL &&
                    bcmp(cp->rname, name, strlen(name) + 1) == 0) {
                        if (BEFORE(timestamp, &cp->laststamp)) {
                                svcauthdes_stats.ncachereplays++;
                                return (-1); /* replay */
                        }
                        svcauthdes_stats.ncachehits++;
                        return (i);     /* refresh */
                }
        }
        svcauthdes_stats.ncachemisses++;
        return (cache_victim());        /* new credential */
}


#if (defined(sun) || defined(vax) || defined(__FreeBSD__))
/*
 * Local credential handling stuff.
 * NOTE: bsd unix dependent.
 * Other operating systems should put something else here.
 */
#define UNKNOWN         -2      /* grouplen, if cached cred is unknown user */
#define INVALID         -1      /* grouplen, if cache entry is invalid */

struct bsdcred {
        uid_t uid;              /* cached uid */
        gid_t gid;              /* cached gid */
        int grouplen;   /* length of cached groups */
        gid_t groups[NGRPS];    /* cached groups */
};

/*
 * Map a des credential into a unix cred.
 * We cache the credential here so the application does
 * not have to make an rpc call every time to interpret
 * the credential.
 */
int
authdes_getucred(struct authdes_cred *adc, uid_t *uid, gid_t *gid,
    int *grouplen, gid_t *groups)
{
        unsigned sid;
        int i;
        uid_t i_uid;    
        gid_t i_gid;
        int i_grouplen;
        struct bsdcred *cred;

        sid = adc->adc_nickname;
        if (sid >= AUTHDES_CACHESZ) {
                debug("invalid nickname");
                return (0);
        }
        cred = (struct bsdcred *)authdes_cache[sid].localcred;
        if (cred == NULL) {
                cred = (struct bsdcred *)mem_alloc(sizeof(struct bsdcred));
                authdes_cache[sid].localcred = (char *)cred;
                cred->grouplen = INVALID;
        }
        if (cred->grouplen == INVALID) {
                /*
                 * not in cache: lookup
                 */
                if (!netname2user(adc->adc_fullname.name, &i_uid, &i_gid, 
                        &i_grouplen, groups))
                {
                        debug("unknown netname");
                        cred->grouplen = UNKNOWN;       /* mark as lookup up, but not found */
                        return (0);
                }
                debug("missed ucred cache");
                *uid = cred->uid = i_uid;
                *gid = cred->gid = i_gid;
                *grouplen = cred->grouplen = i_grouplen;
                for (i = i_grouplen - 1; i >= 0; i--) {
                        cred->groups[i] = groups[i]; /* int to short */
                }
                return (1);
        } else if (cred->grouplen == UNKNOWN) {
                /*
                 * Already lookup up, but no match found
                 */     
                return (0);
        }

        /*
         * cached credentials
         */
        *uid = cred->uid;
        *gid = cred->gid;
        *grouplen = cred->grouplen;
        for (i = cred->grouplen - 1; i >= 0; i--) {
                groups[i] = cred->groups[i];    /* short to int */
        }
        return (1);
}

static void
invalidate(char *cred)
{
        if (cred == NULL) {
                return;
        }
        ((struct bsdcred *)cred)->grouplen = INVALID;
}
#endif