/*

 * Copyright (c) 2010, Oracle America, Inc.

 *

 * 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 the "Oracle America, 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 <limits.h>

#include <string.h>

#include <stdint.h>

#include <sys/param.h>

#include <netinet/in.h>

#include <rpc/rpc.h>

#include <rpc/xdr.h>

#include <rpc/auth.h>

#include <rpc/auth_des.h>

#include <rpc/svc_auth.h>

#include <rpc/svc.h>

#include <rpc/des_crypt.h>

#include <shlib-compat.h>

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

#define USEC_PER_SEC ((uint32_t) 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 rpc_timeval laststamp;	/* detect replays of creds */

    char *localcred;		/* generic local credential */

  };

#define authdes_cache RPC_THREAD_VARIABLE(authdes_cache_s)

#define authdes_lru RPC_THREAD_VARIABLE(authdes_lru_s)

static void cache_init (void); /* initialize the cache */

static short cache_spot (des_block *, char *, struct rpc_timeval *);

  /* find an entry in the cache */

static void cache_ref (uint32_t sid); /* note that sid was ref'd */

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

/* Cache statistics.  Accidental historic export without a matching

   declaration in any header file.  */

#ifndef SHARED

static

#endif

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 __attribute__ ((nocommon));

#ifdef SHARED

compat_symbol (libc, svcauthdes_stats, svcauthdes_stats, GLIBC_2_0);

#endif

/*

 * Service side authenticator for AUTH_DES

 */

enum auth_stat

_svcauth_des (register struct svc_req *rqst, register struct rpc_msg *msg)

{

  register uint32_t *ixdr;

  des_block cryptbuf[2];

  register struct authdes_cred *cred;

  struct authdes_verf verf;

  int status;

  register struct cache_entry *entry;

  uint32_t sid = 0;

  des_block *sessionkey;

  des_block ivec;

  u_int window;

  struct rpc_timeval timestamp;

  uint32_t namelen;

  struct area

    {

      struct authdes_cred area_cred;

      char area_netname[MAXNETNAMELEN + 1];

    }

   *area;

  if (authdes_cache == NULL)

    cache_init ();

  if (authdes_cache == NULL) /* No free memory */

    return AUTH_FAILED;

  area = (struct area *) rqst->rq_clntcred;

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

  /*

   * Get the credential

   */

  if (msg->rm_call.cb_cred.oa_length <= 0 ||

      msg->rm_call.cb_cred.oa_length > MAX_AUTH_BYTES)

    return AUTH_BADCRED;

  ixdr = (uint32_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;

      memcpy (cred->adc_fullname.name, (char *) ixdr, namelen);

      cred->adc_fullname.name[namelen] = 0;

      ixdr += (RNDUP (namelen) / BYTES_PER_XDR_UNIT);

      cred->adc_fullname.key.key.high = *ixdr++;

      cred->adc_fullname.key.key.low = *ixdr++;

      cred->adc_fullname.window = *ixdr++;

      break;

    case ADN_NICKNAME:

      cred->adc_nickname = *ixdr++;

      break;

    default:

      return AUTH_BADCRED;

    }

  /*

   * Get the verifier

   */

  if (msg->rm_call.cb_verf.oa_length <= 0 ||

      msg->rm_call.cb_verf.oa_length > MAX_AUTH_BYTES)

    return AUTH_BADCRED;

  ixdr = (uint32_t *) msg->rm_call.cb_verf.oa_base;

  verf.adv_xtimestamp.key.high = *ixdr++;

  verf.adv_xtimestamp.key.low = *ixdr++;

  verf.adv_int_u = *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 */

      if (cred->adc_nickname >= AUTHDES_CACHESZ)

	{

	  debug ("bad nickname");

	  return AUTH_BADCRED;	/* garbled credential */

	}

      else

	sid = cred->adc_nickname;

      /* XXX This could be wrong, but else we have a

	 security problem */

      if (authdes_cache[sid].rname == NULL)

	return AUTH_BADCRED;

      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 = (uint32_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.

   */

  {

    struct timeval current;

    int nick;

    u_int winverf;

    if (cred->adc_namekind == ADN_FULLNAME)

      {

	short tmp_spot;

	window = IXDR_GET_U_INT32 (ixdr);

	winverf = IXDR_GET_U_INT32 (ixdr);

	if (winverf != window - 1)

	  {

	    debug ("window verifier mismatch");

	    return AUTH_BADCRED;	/* garbled credential */

	  }

	tmp_spot = cache_spot (sessionkey, cred->adc_fullname.name,

			       &timestamp);

	if (tmp_spot < 0 || tmp_spot > AUTHDES_CACHESZ)

	  {

	    debug ("replayed credential");

	    return AUTH_REJECTEDCRED;		/* replay */

	  }

	sid = tmp_spot;

	nick = 0;

      }

    else

      {				/* ADN_NICKNAME */

	window = authdes_cache[sid].window;

	nick = 1;

      }

    if (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 */

      }

    __gettimeofday (&current, (struct timezone *) 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 = sid;

  /*

   * xdr the timestamp before encrypting

   */

  ixdr = (uint32_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 | 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 = (uint32_t *) msg->rm_call.cb_verf.oa_base;

  *ixdr++ = verf.adv_xtimestamp.key.high;

  *ixdr++ = verf.adv_xtimestamp.key.low;

  *ixdr++ = 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)

    {

      size_t full_len;

      cred->adc_fullname.window = window;

      cred->adc_nickname = sid;	/* save nickname */

      if (entry->rname != NULL)

	mem_free (entry->rname, strlen (entry->rname) + 1);

      full_len = strlen (cred->adc_fullname.name) + 1;

      entry->rname = mem_alloc ((u_int) full_len);

      if (entry->rname != NULL)

	memcpy (entry->rname, cred->adc_fullname.name, full_len);

      else

	{

	  debug ("out of memory");

	  return AUTH_FAILED; /* out of memory is bad */

	}

      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)

{

  register int i;

  authdes_cache = (struct cache_entry *)

    calloc (sizeof (struct cache_entry) * AUTHDES_CACHESZ, 1);

  if (authdes_cache == NULL)

    return;

  authdes_lru = (int *) mem_alloc (sizeof (int) * 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 (register uint32_t sid)

{

  register int i;

  register int curr;

  register int 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 (register des_block *key, char *name,

	    struct rpc_timeval *timestamp)

{

  register struct cache_entry *cp;

  register int i;

  register uint32_t 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 &&

	  memcmp (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 */

}

/*

 * 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 */

  int grouplen_max;		/* length of allocated cached groups */

  gid_t groups[0];		/* 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 (const struct authdes_cred *adc, uid_t * uid, gid_t * gid,

		  short *grouplen, gid_t * groups)

{

  unsigned sid;

  register 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->grouplen == INVALID)

    {

      /*

       * not in cache: lookup

       */

      if (!netname2user (adc->adc_fullname.name, &i_uid, &i_gid,

			 &i_grouplen, groups))

	{

	  debug ("unknown netname");

	  if (cred != NULL)

	    cred->grouplen = UNKNOWN;	/* mark as lookup up, but not found */

	  return 0;

	}

      if (cred != NULL && cred->grouplen_max < i_grouplen)

	{

	  /* We already have an allocated data structure.  But it is

	     too small.  */

	  free (cred);

	  authdes_cache[sid].localcred = NULL;

	  cred = NULL;

	}

      if (cred == NULL)

	{

	  /* We should allocate room for at least NGROUPS groups.  */

	  int ngroups_max = MAX (i_grouplen, NGROUPS);

	  cred = (struct bsdcred *) mem_alloc (sizeof (struct bsdcred)

					       + ngroups_max * sizeof (gid_t));

	  if (cred == NULL)

	    return 0;

	  authdes_cache[sid].localcred = (char *) cred;

	  cred->grouplen = INVALID;

	  cred->grouplen_max = ngroups_max;

	}

      debug ("missed ucred cache");

      *uid = cred->uid = i_uid;

      *gid = cred->gid = i_gid;

      cred->grouplen = i_grouplen;

      for (i = i_grouplen - 1; i >= 0; --i)

	cred->groups[i] = groups[i];

      /* Make sure no too large values are reported.  */

      *grouplen = MIN (SHRT_MAX, i_grouplen);

      return 1;

    }

  else if (cred->grouplen == UNKNOWN)

    {

      /*

       * Already lookup up, but no match found

       */

      return 0;

    }

  /*

   * cached credentials

   */

  *uid = cred->uid;

  *gid = cred->gid;

  /* Another stupidity in the interface: *grouplen is of type short.

     So we might have to cut the information passed up short.  */

  int grouplen_copy = MIN (SHRT_MAX, cred->grouplen);

  *grouplen = grouplen_copy;

  for (i = grouplen_copy - 1; i >= 0; --i)

    groups[i] = cred->groups[i];

  return 1;

}

libc_hidden_nolink_sunrpc (authdes_getucred, GLIBC_2_1)

static void

invalidate (char *cred)

{

  if (cred == NULL)

    return;

  ((struct bsdcred *) cred)->grouplen = INVALID;

}