samba-mirror/source3/smbd/uid.c

/* 
   Unix SMB/Netbios implementation.
   Version 1.9.
   uid/user handling
   Copyright (C) Andrew Tridgell 1992-1998
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"

extern int DEBUGLEVEL;

static uid_t initial_uid;
static gid_t initial_gid;

/* what user is current? */
extern struct current_user current_user;

pstring OriginalDir;

/****************************************************************************
initialise the uid routines
****************************************************************************/
void init_uid(void)
{
	initial_uid = current_user.uid = geteuid();
	initial_gid = current_user.gid = getegid();

	if (initial_gid != 0 && initial_uid == 0) {
#ifdef HAVE_SETRESUID
		setresgid(0,0,0);
#else
		setgid(0);
		setegid(0);
#endif
	}

	initial_uid = geteuid();
	initial_gid = getegid();

	current_user.conn = NULL;
	current_user.vuid = UID_FIELD_INVALID;
	
	dos_ChDir(OriginalDir);
}


/****************************************************************************
  become the specified uid 
****************************************************************************/
static BOOL become_uid(uid_t uid)
{
	if (initial_uid != 0) {
		return(True);
	}
	
	if (uid == (uid_t)-1 || ((sizeof(uid_t) == 2) && (uid == (uid_t)65535))) {
		static int done;
		if (!done) {
			DEBUG(1,("WARNING: using uid %d is a security risk\n",(int)uid));
			done=1;
		}
	}

#ifdef HAVE_TRAPDOOR_UID
#ifdef HAVE_SETUIDX
	/* AIX3 has setuidx which is NOT a trapoor function (tridge) */
	if (setuidx(ID_EFFECTIVE, uid) != 0) {
		if (seteuid(uid) != 0) {
			DEBUG(1,("Can't set uid %d (setuidx)\n", (int)uid));
			return False;
		}
	}
#endif
#endif

#ifdef HAVE_SETRESUID
    if (setresuid(-1,uid,-1) != 0)
#else
    if ((seteuid(uid) != 0) && 
	(setuid(uid) != 0))
#endif
      {
	DEBUG(0,("Couldn't set uid %d currently set to (%d,%d)\n",
		 (int)uid,(int)getuid(), (int)geteuid()));
	if (uid > (uid_t)32000) {
		DEBUG(0,("Looks like your OS doesn't like high uid values - try using a different account\n"));
	}
	return(False);
      }

    if (((uid == (uid_t)-1) || ((sizeof(uid_t) == 2) && (uid == 65535))) && (geteuid() != uid)) {
	    DEBUG(0,("Invalid uid -1. perhaps you have a account with uid 65535?\n"));
	    return(False);
    }

    current_user.uid = uid;

    return(True);
}


/****************************************************************************
  become the specified gid
****************************************************************************/
static BOOL become_gid(gid_t gid)
{
  if (initial_uid != 0)
    return(True);

  if (gid == (gid_t)-1 || ((sizeof(gid_t) == 2) && (gid == (gid_t)65535))) {
    DEBUG(1,("WARNING: using gid %d is a security risk\n",(int)gid));    
  }
  
#ifdef HAVE_SETRESUID
  if (setresgid(-1,gid,-1) != 0)
#else
  if (setgid(gid) != 0)
#endif
      {
	DEBUG(0,("Couldn't set gid %d currently set to (%d,%d)\n",
		 (int)gid,(int)getgid(),(int)getegid()));
	if (gid > 32000) {
		DEBUG(0,("Looks like your OS doesn't like high gid values - try using a different account\n"));
	}
	return(False);
      }

  current_user.gid = gid;

  return(True);
}


/****************************************************************************
  become the specified uid and gid
****************************************************************************/
static BOOL become_id(uid_t uid,gid_t gid)
{
	return(become_gid(gid) && become_uid(uid));
}

/****************************************************************************
become the guest user
****************************************************************************/
BOOL become_guest(void)
{
  BOOL ret;
  static struct passwd *pass=NULL;

  if (initial_uid != 0) 
    return(True);

  if (!pass)
    pass = Get_Pwnam(lp_guestaccount(-1),True);
  if (!pass) return(False);

#ifdef AIX
  /* MWW: From AIX FAQ patch to WU-ftpd: call initgroups before setting IDs */
  initgroups(pass->pw_name, (gid_t)pass->pw_gid);
#endif

  ret = become_id(pass->pw_uid,pass->pw_gid);

  if (!ret) {
    DEBUG(1,("Failed to become guest. Invalid guest account?\n"));
  }

  current_user.conn = NULL;
  current_user.vuid = UID_FIELD_INVALID;

  return(ret);
}

/*******************************************************************
check if a username is OK
********************************************************************/
static BOOL check_user_ok(connection_struct *conn, user_struct *vuser,int snum)
{
  int i;
  for (i=0;i<conn->uid_cache.entries;i++)
    if (conn->uid_cache.list[i] == vuser->uid) return(True);

  if (!user_ok(vuser->name,snum)) return(False);

  i = conn->uid_cache.entries % UID_CACHE_SIZE;
  conn->uid_cache.list[i] = vuser->uid;

  if (conn->uid_cache.entries < UID_CACHE_SIZE)
    conn->uid_cache.entries++;

  return(True);
}


/****************************************************************************
  become the user of a connection number
****************************************************************************/
BOOL become_user(connection_struct *conn, uint16 vuid)
{
	user_struct *vuser = get_valid_user_struct(vuid);
	int snum;
    gid_t gid;
	uid_t uid;

	/*
	 * We need a separate check in security=share mode due to vuid
	 * always being UID_FIELD_INVALID. If we don't do this then
	 * in share mode security we are *always* changing uid's between
	 * SMB's - this hurts performance - Badly.
	 */

	if((lp_security() == SEC_SHARE) && (current_user.conn == conn) &&
	   (current_user.uid == conn->uid)) {
		DEBUG(4,("Skipping become_user - already user\n"));
		return(True);
	} else if ((current_user.conn == conn) && 
		   (vuser != 0) && (current_user.vuid == vuid) && 
		   (current_user.uid == vuser->uid)) {
		DEBUG(4,("Skipping become_user - already user\n"));
		return(True);
	}

	unbecome_user();

	if (!conn) {
		DEBUG(2,("Connection not open\n"));
		return(False);
	}

	snum = SNUM(conn);

	if((vuser != NULL) && !check_user_ok(conn, vuser, snum))
		return False;

	if (conn->force_user || 
	    lp_security() == SEC_SHARE ||
	    !(vuser) || (vuser->guest)) {
		uid = conn->uid;
		gid = conn->gid;
		current_user.groups = conn->groups;
		current_user.ngroups = conn->ngroups;
	} else {
		if (!vuser) {
			DEBUG(2,("Invalid vuid used %d\n",vuid));
			return(False);
		}
		uid = vuser->uid;
		if(!*lp_force_group(snum)) {
			gid = vuser->gid;
		} else {
			gid = conn->gid;
		}
		current_user.ngroups = vuser->n_groups;
		current_user.groups  = vuser->groups;
	}
	
	if (initial_uid == 0)  {
		if (!become_gid(gid)) return(False);

#ifdef HAVE_SETGROUPS      
		if (!(conn && conn->ipc)) {
			/* groups stuff added by ih/wreu */
			if (current_user.ngroups > 0)
				if (setgroups(current_user.ngroups,
					      current_user.groups)<0) {
					DEBUG(0,("setgroups call failed!\n"));
				}
		}
#endif

		if (!conn->admin_user && !become_uid(uid))
			return(False);
	}
	
	current_user.conn = conn;
	current_user.vuid = vuid;

	DEBUG(5,("become_user uid=(%d,%d) gid=(%d,%d)\n",
		 (int)getuid(),(int)geteuid(),(int)getgid(),(int)getegid()));
  
	return(True);
}

/****************************************************************************
  unbecome the user of a connection number
****************************************************************************/
BOOL unbecome_user(void )
{
  if (!current_user.conn)
    return(False);

  dos_ChDir(OriginalDir);

  if (initial_uid == 0)
    {
#ifdef HAVE_SETRESUID
      setresuid(-1,getuid(),-1);
      setresgid(-1,getgid(),-1);
#else
      if (seteuid(initial_uid) != 0) 
	setuid(initial_uid);
      setgid(initial_gid);
#endif
    }

#ifdef NO_EID
  if (initial_uid == 0)
    DEBUG(2,("Running with no EID\n"));
  initial_uid = getuid();
  initial_gid = getgid();
#else
  if (geteuid() != initial_uid) {
	  DEBUG(0,("Warning: You appear to have a trapdoor uid system\n"));
	  initial_uid = geteuid();
  }
  if (getegid() != initial_gid) {
	  DEBUG(0,("Warning: You appear to have a trapdoor gid system\n"));
	  initial_gid = getegid();
  }
#endif

  current_user.uid = initial_uid;
  current_user.gid = initial_gid;
  
  if (dos_ChDir(OriginalDir) != 0)
    DEBUG( 0, ( "chdir(%s) failed in unbecome_user\n", OriginalDir ) );

  DEBUG(5,("unbecome_user now uid=(%d,%d) gid=(%d,%d)\n",
	(int)getuid(),(int)geteuid(),(int)getgid(),(int)getegid()));

  current_user.conn = NULL;
  current_user.vuid = UID_FIELD_INVALID;

  return(True);
}

static struct current_user current_user_saved;
static int become_root_depth;
static pstring become_root_dir;

/****************************************************************************
This is used when we need to do a privilaged operation (such as mucking
with share mode files) and temporarily need root access to do it. This
call should always be paired with an unbecome_root() call immediately
after the operation

Set save_dir if you also need to save/restore the CWD 
****************************************************************************/
void become_root(BOOL save_dir) 
{
	if (become_root_depth) {
		DEBUG(0,("ERROR: become root depth is non zero\n"));
	}
	if (save_dir)
		dos_GetWd(become_root_dir);

	current_user_saved = current_user;
	become_root_depth = 1;

	become_uid(0);
	become_gid(0);
}

/****************************************************************************
When the privilaged operation is over call this

Set save_dir if you also need to save/restore the CWD 
****************************************************************************/
void unbecome_root(BOOL restore_dir)
{
	if (become_root_depth != 1) {
		DEBUG(0,("ERROR: unbecome root depth is %d\n",
			 become_root_depth));
	}

	/* we might have done a become_user() while running as root,
	   if we have then become root again in order to become 
	   non root! */
	if (current_user.uid != 0) {
		become_uid(0);
	}

	/* restore our gid first */
	if (!become_gid(current_user_saved.gid)) {
		DEBUG(0,("ERROR: Failed to restore gid\n"));
		exit_server("Failed to restore gid");
	}

#ifdef HAVE_SETGROUPS      
	if (current_user_saved.ngroups > 0) {
		if (setgroups(current_user_saved.ngroups,
			      current_user_saved.groups)<0)
			DEBUG(0,("ERROR: setgroups call failed!\n"));
	}
#endif

	/* now restore our uid */
	if (!become_uid(current_user_saved.uid)) {
		DEBUG(0,("ERROR: Failed to restore uid\n"));
		exit_server("Failed to restore uid");
	}

	if (restore_dir)
		dos_ChDir(become_root_dir);

	current_user = current_user_saved;

	become_root_depth = 0;
}