/*
 * 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 2017 Joyent Inc
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T     */
/*        All Rights Reserved   */

/*
 * Portions of this source code were derived from Berkeley 4.3 BSD
 * under license from the Regents of the University of California.
 */

/*
 * 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 <sys/types.h>
#include <sys/time.h>
#include <sys/systm.h>
#include <sys/param.h>
#include <sys/stream.h>
#include <sys/stropts.h>
#include <sys/strsubr.h>
#include <sys/tiuser.h>
#include <sys/tihdr.h>
#include <sys/t_kuser.h>
#include <sys/t_lock.h>
#include <sys/debug.h>
#include <sys/kmem.h>
#include <sys/time.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>

#include <rpc/types.h>
#include <rpc/xdr.h>
#include <rpc/auth.h>
#include <rpc/auth_des.h>
#include <rpc/rpc_msg.h>
#include <rpc/svc.h>
#include <rpc/svc_auth.h>
#include <rpc/clnt.h>
#include <rpc/des_crypt.h>

#define USEC_PER_SEC 1000000
#define BEFORE(t1, t2) timercmp(t1, t2, < /* COMMENT HERE TO DEFEAT CSTYLE */)

/*
 * Cache of conversation keys and some other useful items.
 * The hash table size is controled via authdes_cachesz variable.
 * The authdes_cachesz has to be the power of 2.
 */
#define AUTHDES_CACHE_TABLE_SZ 1024
static int authdes_cachesz = AUTHDES_CACHE_TABLE_SZ;
#define HASH(key) ((key) & (authdes_cachesz - 1))

/* low water mark for the number of cache entries */
static int low_cache_entries = 128;

struct authdes_cache_entry {
        uint32_t nickname;              /* nick name id */
        uint32_t window;                /* credential lifetime window */
        des_block key;                  /* conversation key */
        time_t  ref_time;               /* time referenced previously */
        char *rname;                    /* client's name */
        caddr_t localcred;              /* generic local credential */
        struct authdes_cache_entry *prev, *next;  /* hash table linked list */
        struct authdes_cache_entry *lru_prev, *lru_next; /* LRU linked list */
        kmutex_t lock;                  /* cache entry lock */
};
static struct authdes_cache_entry **authdes_cache; /* [authdes_cachesz] */
static struct authdes_cache_entry *lru_first = NULL;
static struct authdes_cache_entry *lru_last = NULL;
static kmutex_t authdes_lock;           /* cache table lock */

static struct kmem_cache *authdes_cache_handle;
static uint32_t Nickname = 0;

static struct authdes_cache_entry *authdes_cache_new(char *,
                                        des_block *, uint32_t);
static struct authdes_cache_entry *authdes_cache_get(uint32_t);
static void authdes_cache_reclaim(void *);
static void sweep_cache();

/*
 * After 12 hours, check and delete cache entries that have been
 * idled for more than 10 hours.
 */
static time_t authdes_sweep_interval = 12*60*60;
static time_t authdes_cache_time = 10*60*60;
static time_t authdes_last_swept = 0;

/*
 * cache statistics
 */
static int authdes_ncache = 0; /* number of current cached entries */
static int authdes_ncachehits = 0; /* #times cache hit */
static int authdes_ncachemisses = 0; /* #times cache missed */

#define NOT_DEAD(ptr)   ASSERT((((intptr_t)(ptr)) != 0xdeadbeef))
#define IS_ALIGNED(ptr) ASSERT((((intptr_t)(ptr)) & 3) == 0)

/*
 * Service side authenticator for AUTH_DES
 */
enum auth_stat
_svcauth_des(struct svc_req *rqst, struct rpc_msg *msg)
{
        int32_t *ixdr;
        des_block cryptbuf[2];
        struct authdes_cred *cred;
        struct authdes_verf verf;
        int status;
        des_block *sessionkey;
        des_block ivec;
        uint32_t window, winverf, namelen;
        bool_t nick;
        struct timeval timestamp, current_time;
        struct authdes_cache_entry *nick_entry;
        struct area {
                struct authdes_cred area_cred;
                char area_netname[MAXNETNAMELEN+1];
        } *area;
        timestruc_t now;

        mutex_enter(&authdes_lock);
        if (authdes_cache == NULL) {
                authdes_cache = kmem_zalloc(
                        sizeof (struct authdes_cache_entry *) * authdes_cachesz,
                        KM_SLEEP);
        }
        mutex_exit(&authdes_lock);

        CTASSERT(sizeof (struct area) <= RQCRED_SIZE);
        /* LINTED pointer alignment */
        area = (struct area *)rqst->rq_clntcred;
        cred = (struct authdes_cred *)&area->area_cred;

        /*
         * Get the credential
         */
        /* LINTED pointer alignment */
        ixdr = (int32_t *)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_INT32(ixdr);
                if (namelen > MAXNETNAMELEN)
                        return (AUTH_BADCRED);
                cred->adc_fullname.name = area->area_netname;
                bcopy(ixdr, cred->adc_fullname.name, namelen);
                cred->adc_fullname.name[namelen] = 0;
                ixdr += (RNDUP(namelen) / BYTES_PER_XDR_UNIT);
                cred->adc_fullname.key.key.high = (uint32_t)*ixdr++;
                cred->adc_fullname.key.key.low = (uint32_t)*ixdr++;
                cred->adc_fullname.window = (uint32_t)*ixdr++;
                nick = FALSE;
                break;
        case ADN_NICKNAME:
                cred->adc_nickname = (uint32_t)*ixdr++;
                nick = TRUE;
                break;
        default:
                return (AUTH_BADCRED);
        }

        /*
         * Get the verifier
         */
        /* LINTED pointer alignment */
        ixdr = (int32_t *)msg->rm_call.cb_verf.oa_base;
        verf.adv_xtimestamp.key.high = (uint32_t)*ixdr++;
        verf.adv_xtimestamp.key.low =  (uint32_t)*ixdr++;
        verf.adv_int_u = (uint32_t)*ixdr++;


        /*
         * Get the conversation key
         */
        if (!nick) { /* ADN_FULLNAME */
                sessionkey = &cred->adc_fullname.key;
                if (key_decryptsession(cred->adc_fullname.name, sessionkey) !=
                    RPC_SUCCESS) {
                    return (AUTH_BADCRED); /* key not found */
                }
        } else { /* ADN_NICKNAME */
                mutex_enter(&authdes_lock);
                if (!(nick_entry = authdes_cache_get(cred->adc_nickname))) {
                    RPCLOG(1, "_svcauth_des: nickname %d not in the cache\n",
                                                cred->adc_nickname);
                    mutex_exit(&authdes_lock);
                    return (AUTH_BADCRED);      /* need refresh */
                }
                sessionkey = &nick_entry->key;
                mutex_enter(&nick_entry->lock);
                mutex_exit(&authdes_lock);
        }

        /*
         * Decrypt the timestamp
         */
        cryptbuf[0] = verf.adv_xtimestamp;
        if (!nick) { /* 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, (char *)&ivec);
        } else { /* ADN_NICKNAME */
                status = ecb_crypt((char *)sessionkey, (char *)cryptbuf,
                    sizeof (des_block), DES_DECRYPT);
        }
        if (DES_FAILED(status)) {
                RPCLOG0(1, "_svcauth_des: decryption failure\n");
                if (nick) {
                        mutex_exit(&nick_entry->lock);
                }
                return (AUTH_FAILED);   /* system error */
        }

        /*
         * XDR the decrypted timestamp
         */
        ixdr = (int32_t *)cryptbuf;
        timestamp.tv_sec = IXDR_GET_INT32(ixdr);
        timestamp.tv_usec = IXDR_GET_INT32(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.
         */
        if (!nick) { /* ADN_FULLNAME */
                window = IXDR_GET_U_INT32(ixdr);
                winverf = IXDR_GET_U_INT32(ixdr);
                if (winverf != window - 1) {
                        RPCLOG(1, "_svcauth_des: window verifier mismatch %d\n",
                                winverf);
                        return (AUTH_BADCRED);  /* garbled credential */
                }
        } else { /* ADN_NICKNAME */
                window = nick_entry->window;
        }

        if (timestamp.tv_usec >= USEC_PER_SEC) {
                RPCLOG(1, "_svcauth_des: invalid usecs %ld\n",
                                        timestamp.tv_usec);
                /* cached out (bad key), or garbled verifier */
                if (nick) {
                        mutex_exit(&nick_entry->lock);
                }
                return (nick ? AUTH_REJECTEDVERF : AUTH_BADVERF);
        }

        gethrestime(&now);
        current_time.tv_sec = now.tv_sec;
        current_time.tv_usec = now.tv_nsec / 1000;

        current_time.tv_sec -= window;  /* allow for expiration */
        if (!BEFORE(&current_time, &timestamp)) {
                RPCLOG0(1, "_svcauth_des: timestamp expired\n");
                /* replay, or garbled credential */
                if (nick) {
                        mutex_exit(&nick_entry->lock);
                }
                return (nick ? AUTH_REJECTEDVERF : AUTH_BADCRED);
        }

        /*
         * xdr the timestamp before encrypting
         */
        ixdr = (int32_t *)cryptbuf;
        IXDR_PUT_INT32(ixdr, timestamp.tv_sec - 1);
        IXDR_PUT_INT32(ixdr, timestamp.tv_usec);

        /*
         * encrypt the timestamp
         */
        status = ecb_crypt((char *)sessionkey, (char *)cryptbuf,
            sizeof (des_block), DES_ENCRYPT);
        if (DES_FAILED(status)) {
                RPCLOG0(1, "_svcauth_des: encryption failure\n");
                if (nick) {
                        mutex_exit(&nick_entry->lock);
                }
                return (AUTH_FAILED);   /* system error */
        }
        verf.adv_xtimestamp = cryptbuf[0];

        /*
         * If a ADN_FULLNAME, create a new nickname cache entry.
         */
        if (!nick) {
            mutex_enter(&authdes_lock);
            if (!(nick_entry = authdes_cache_new(cred->adc_fullname.name,
                                        sessionkey, window))) {
                RPCLOG0(1, "_svcauth_des: can not create new cache entry\n");
                mutex_exit(&authdes_lock);
                return (AUTH_FAILED);
            }
            mutex_enter(&nick_entry->lock);
            mutex_exit(&authdes_lock);
        }
        verf.adv_nickname = nick_entry->nickname;

        /*
         * Serialize the reply verifier, and update rqst
         */
        /* LINTED pointer alignment */
        ixdr = (int32_t *)msg->rm_call.cb_verf.oa_base;
        *ixdr++ = (int32_t)verf.adv_xtimestamp.key.high;
        *ixdr++ = (int32_t)verf.adv_xtimestamp.key.low;
        *ixdr++ = (int32_t)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 =
            (uint_t)((char *)ixdr - msg->rm_call.cb_verf.oa_base);
        if (rqst->rq_xprt->xp_verf.oa_length > MAX_AUTH_BYTES) {
                RPCLOG0(1, "_svcauth_des: invalid oa length\n");
                mutex_exit(&nick_entry->lock);
                return (AUTH_BADVERF);
        }

        /*
         * We succeeded and finish cooking the credential.
         * nicknames are cooked into fullnames
         */
        if (!nick) {
                cred->adc_nickname = nick_entry->nickname;
                cred->adc_fullname.window = window;
        } else { /* ADN_NICKNAME */
                cred->adc_namekind = ADN_FULLNAME;
                cred->adc_fullname.name = nick_entry->rname;
                cred->adc_fullname.key = nick_entry->key;
                cred->adc_fullname.window = nick_entry->window;
        }
        mutex_exit(&nick_entry->lock);

        /*
         * For every authdes_sweep_interval, delete cache entries that have been
         * idled for authdes_cache_time.
         */
        mutex_enter(&authdes_lock);
        if ((gethrestime_sec() - authdes_last_swept) > authdes_sweep_interval)
                sweep_cache();

        mutex_exit(&authdes_lock);

        return (AUTH_OK);       /* we made it! */
}

/*
 * Initialization upon loading the rpcsec module.
 */
void
svcauthdes_init(void)
{
        mutex_init(&authdes_lock, NULL, MUTEX_DEFAULT, NULL);
        /*
         * Allocate des cache handle
         */
        authdes_cache_handle = kmem_cache_create("authdes_cache_handle",
                        sizeof (struct authdes_cache_entry), 0, NULL, NULL,
                        authdes_cache_reclaim, NULL, NULL, 0);
}

/*
 * Final actions upon exiting the rpcsec module.
 */
void
svcauthdes_fini(void)
{
        mutex_destroy(&authdes_lock);
        kmem_cache_destroy(authdes_cache_handle);
}

/*
 * Local credential handling stuff.
 * NOTE: bsd unix dependent.
 * Other operating systems should put something else here.
 */

struct bsdcred {
        uid_t uid;              /* cached uid */
        gid_t gid;              /* cached gid */
        short valid;            /* valid creds */
        short grouplen; /* length of cached groups */
        gid_t groups[1];        /* cached groups - allocate ngroups_max */
};

/*
 * 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
kauthdes_getucred(const struct authdes_cred *adc, cred_t *cr)
{
        uid_t i_uid;
        gid_t i_gid;
        int i_grouplen;
        struct bsdcred *cred;
        struct authdes_cache_entry *nickentry;

        mutex_enter(&authdes_lock);
        if (!(nickentry = authdes_cache_get(adc->adc_nickname))) {
                RPCLOG0(1, "authdes_getucred:  invalid nickname\n");
                mutex_exit(&authdes_lock);
                return (0);
        }

        mutex_enter(&nickentry->lock);
        mutex_exit(&authdes_lock);
        /* LINTED pointer alignment */
        cred = (struct bsdcred *)nickentry->localcred;
        if (!cred->valid) {
                /*
                 * not in cache: lookup
                 */
                if (netname2user(adc->adc_fullname.name, &i_uid, &i_gid,
                    &i_grouplen, &cred->groups[0]) != RPC_SUCCESS) {
                        /*
                         * Probably a host principal, since at this
                         * point we have valid keys. Note that later
                         * if the principal is not in the root list
                         * for NFS, we will be mapped to that exported
                         * file system's anonymous user, typically
                         * NOBODY. keyserv KEY_GETCRED will fail for a
                         * root-netnames so we assume root here.
                         * Currently NFS is the only caller of this
                         * routine. If other RPC services call this
                         * routine, it is up to that service to
                         * differentiate between local and remote
                         * roots.
                         */
                        i_uid = 0;
                        i_gid = 0;
                        i_grouplen = 0;
                }
                RPCLOG0(2, "authdes_getucred:  missed ucred cache\n");
                cred->uid = i_uid;
                cred->gid = i_gid;
                cred->grouplen = (short)i_grouplen;
                cred->valid = 1;
        }

        /*
         * cached credentials
         */
        if (crsetugid(cr, cred->uid, cred->gid) != 0 ||
            crsetgroups(cr, cred->grouplen, &cred->groups[0]) != 0) {
                mutex_exit(&nickentry->lock);
                return (0);
        }
        mutex_exit(&nickentry->lock);
        return (1);
}

/*
 * Create a new cache_entry and put it in authdes_cache table.
 * Caller should have already locked the authdes_cache table.
 */
struct authdes_cache_entry *
authdes_cache_new(char *fullname, des_block *sessionkey, uint32_t window) {

        struct authdes_cache_entry *new, *head;
        struct bsdcred *ucred;
        int index;

        if (!(new = kmem_cache_alloc(authdes_cache_handle, KM_SLEEP))) {
                return (NULL);
        }

        if (!(new->rname = kmem_alloc(strlen(fullname) + 1, KM_NOSLEEP))) {
                kmem_cache_free(authdes_cache_handle, new);
                return (NULL);
        }

        if (!(ucred = kmem_alloc(sizeof (struct bsdcred) +
            (ngroups_max - 1) * sizeof (gid_t), KM_NOSLEEP))) {
                kmem_free(new->rname, strlen(fullname) + 1);
                kmem_cache_free(authdes_cache_handle, new);
                return (NULL);
        }

        (void) strcpy(new->rname, fullname);
        ucred->valid = 0;
        new->localcred = (caddr_t)ucred;
        new->key = *sessionkey;
        new->window = window;
        new->ref_time = gethrestime_sec();
        new->nickname = Nickname++;
        mutex_init(&new->lock, NULL, MUTEX_DEFAULT, NULL);

        /* put new into the hash table */
        index = HASH(new->nickname);
        head = authdes_cache[index];
        if ((new->next = head) != NULL) {
                head->prev = new;
        }
        authdes_cache[index] = new;
        new->prev = NULL;

        /* update the LRU list */
        new->lru_prev = NULL;
        if ((new->lru_next = lru_first) != NULL) {
                lru_first->lru_prev = new;
        } else {
                lru_last = new;
        }
        lru_first = new;

        authdes_ncache++;
        return (new);
}

/*
 * Get an existing cache entry from authdes_cache table.
 * The caller should have locked the authdes_cache table.
 */
struct authdes_cache_entry *
authdes_cache_get(uint32_t nickname) {

        struct authdes_cache_entry *cur = NULL;
        int index = HASH(nickname);

        ASSERT(MUTEX_HELD(&authdes_lock));
        for (cur = authdes_cache[index]; cur; cur = cur->next) {
                if ((cur->nickname == nickname)) {
                        /* find it, update the LRU list */
                        if (cur != lru_first) {
                            cur->lru_prev->lru_next = cur->lru_next;
                            if (cur->lru_next != NULL) {
                                cur->lru_next->lru_prev = cur->lru_prev;
                            } else {
                                lru_last = cur->lru_prev;
                            }
                            cur->lru_prev = NULL;
                            cur->lru_next = lru_first;
                            lru_first->lru_prev = cur;
                            lru_first = cur;
                        }

                        cur->ref_time = gethrestime_sec();
                        authdes_ncachehits++;
                        return (cur);
                }
        }

        authdes_ncachemisses++;
        return (NULL);
}

/*
 * authdes_cache_reclaim() is called by the kernel memory allocator
 * when memory is low. This routine will reclaim 25% of the least recent
 * used cache entries above the low water mark (low_cache_entries).
 * If the cache entries have already hit the low water mark, it will
 * return 1 cache entry.
 */
/*ARGSUSED*/
void
authdes_cache_reclaim(void *pdata) {
        struct authdes_cache_entry *p;
        int n, i;

        mutex_enter(&authdes_lock);
        n = authdes_ncache - low_cache_entries;
        n = n > 0 ? n/4 : 1;

        for (i = 0; i < n; i++) {
                if ((p = lru_last) == lru_first)
                        break;

                /* Update the hash linked list */
                if (p->prev == NULL) {
                        authdes_cache[HASH(p->nickname)] = p->next;
                } else {
                        p->prev->next = p->next;
                }
                if (p->next != NULL) {
                        p->next->prev = p->prev;
                }

                /* update the LRU linked list */
                p->lru_prev->lru_next = NULL;
                lru_last = p->lru_prev;

                kmem_free(p->rname, strlen(p->rname) + 1);
                kmem_free(p->localcred, sizeof (struct bsdcred) +
                    (ngroups_max - 1) * sizeof (gid_t));
                mutex_destroy(&p->lock);
                kmem_cache_free(authdes_cache_handle, p);

                authdes_ncache--;
        }
        mutex_exit(&authdes_lock);
        RPCLOG(4, "_svcauth_des: %d cache entries reclaimed...\n",
                                authdes_ncache);
}

/*
 *  Walk through the LRU doubly-linked list and delete the cache
 *  entries that have not been used for more than authdes_cache_time.
 *
 *  Caller should have locked the cache table.
 */
void
sweep_cache() {
        struct authdes_cache_entry *p;

        ASSERT(MUTEX_HELD(&authdes_lock));
        while ((p = lru_last) != lru_first) {
                IS_ALIGNED(p);
                NOT_DEAD(p);

                /*
                 * If the last LRU entry idled less than authdes_cache_time,
                 * we are done with the sweeping.
                 */
                if (p->ref_time + authdes_cache_time > gethrestime_sec())
                        break;

                /* update the hash linked list */
                if (p->prev == NULL) {
                        authdes_cache[HASH(p->nickname)] = p->next;
                } else {
                        p->prev->next = p->next;
                }
                if (p->next != NULL) {
                        p->next->prev = p->prev;
                }

                /* update the LRU linked list */
                p->lru_prev->lru_next = NULL;
                lru_last = p->lru_prev;

                kmem_free(p->rname, strlen(p->rname) + 1);
                kmem_free(p->localcred, sizeof (struct bsdcred) +
                    (ngroups_max - 1) * sizeof (gid_t));
                mutex_destroy(&p->lock);
                kmem_cache_free(authdes_cache_handle, p);

                authdes_ncache--;
        }

        authdes_last_swept = gethrestime_sec();
        RPCLOG(4, "_svcauth_des: sweeping cache...#caches left = %d\n",
                                authdes_ncache);
}