/*
 * kadmin/v5server/srv_acl.c
 *
 * Copyright 1995 by the Massachusetts Institute of Technology.
 * All Rights Reserved.
 *
 * Export of this software from the United States of America may
 *   require a specific license from the United States Government.
 *   It is the responsibility of any person or organization contemplating
 *   export to obtain such a license before exporting.
 *
 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
 * distribute this software and its documentation for any purpose and
 * without fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright notice and
 * this permission notice appear in supporting documentation, and that
 * the name of M.I.T. not be used in advertising or publicity pertaining
 * to distribution of the software without specific, written prior
 * permission.  M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is" without express
 * or implied warranty.
 *
 */

/*
 * srv_acl.c - Handle Kerberos ACL related functions.
 */
#include <stdio.h>
#include <syslog.h>
#include <sys/param.h>
#include <gssapi/gssapi_generic.h>
#include "k5-int.h"
#include "server_acl.h"
#include <kadm5/server_internal.h>
#include <ctype.h>

typedef struct _acl_op_table {
    char	ao_op;
    krb5_int32	ao_mask;
} aop_t;

typedef struct _acl_entry {
    struct _acl_entry	*ae_next;
    char		*ae_name;
    krb5_boolean	ae_name_bad;
    krb5_principal	ae_principal;
    krb5_int32		ae_op_allowed;
    char		*ae_target;
    krb5_boolean	ae_target_bad;
    krb5_principal	ae_target_princ;
} aent_t;

static const aop_t acl_op_table[] = {
    { 'a',	ACL_ADD },
    { 'd',	ACL_DELETE },
    { 'm',	ACL_MODIFY },
    { 'c',	ACL_CHANGEPW },
    { 'i',	ACL_INQUIRE },
    { 'l',	ACL_LIST },
    { 's',	ACL_SETKEY },
    { 'x',	ACL_ALL_MASK },
    { '*',	ACL_ALL_MASK },
    { '\0',	0 }
};

static aent_t	*acl_list_head = (aent_t *) NULL;
static aent_t	*acl_list_tail = (aent_t *) NULL;

static const char *acl_acl_file = (char *) NULL;
static int acl_inited = 0;
static int acl_debug_level = 0;
/*
 * This is the catchall entry.  If nothing else appropriate is found, or in
 * the case where the ACL file is not present, this entry controls what can
 * be done.
 */
static const char *acl_catchall_entry = NULL;

static const char *acl_line2long_msg = "%s: line %d too long, truncated";
static const char *acl_op_bad_msg = "Unrecognized ACL operation '%c' in %s";
static const char *acl_syn_err_msg = "%s: syntax error at line %d <%10s...>";
static const char *acl_cantopen_msg = "%s while opening ACL file %s";


/*
 * acl_get_line()	- Get a line from the ACL file.
 */
static char *
acl_get_line(fp, lnp)
    FILE	*fp;
    int		*lnp;
{
    int		i, domore;
    static char acl_buf[BUFSIZ];

    for (domore = 1; domore && !feof(fp); ) {
	/* Copy in the line */
	for (i=0;
	     ((i<BUFSIZ) &&
	      (!feof(fp)) &&
	      ((acl_buf[i] = fgetc(fp)) != '\n'));
	     i++);

	/* Check if we exceeded our buffer size */
	if ((i == BUFSIZ) && (!feof(fp)) && (acl_buf[i] != '\n')) {
	    krb5_klog_syslog(LOG_ERR, acl_line2long_msg, acl_acl_file, *lnp);
	    while (fgetc(fp) != '\n');
	    i--;
	}
		acl_buf[i] = '\0';
	if (acl_buf[0] == (char) EOF)	/* ptooey */
	    acl_buf[0] = '\0';
	else
	    (*lnp)++;
	if ((acl_buf[0] != '#') && (acl_buf[0] != '\0'))
	    domore = 0;
    }
    if (domore || (strlen(acl_buf) == 0))
	return((char *) NULL);
    else
	return(acl_buf);
}

/*
 * acl_parse_line()	- Parse the contents of an ACL line.
 */
static aent_t *
acl_parse_line(lp)
    char *lp;
{
    static char acle_principal[BUFSIZ];
    static char acle_ops[BUFSIZ];
    static char acle_object[BUFSIZ];
    aent_t	*acle;
    char	*op;
    int		t, found, opok, nmatch;

    DPRINT(DEBUG_CALLS, acl_debug_level,
	   ("* acl_parse_line(line=%20s)\n", lp));
    /*
     * Format is very simple:
     *	entry ::= <whitespace> <principal> <whitespace> <opstring> <whitespace>
     *		  [<target> <whitespace>]
     */
    acle = (aent_t *) NULL;
    acle_object[0] = '\0';
    nmatch = sscanf(lp, "%s %s %s", acle_principal, acle_ops, acle_object);
    if (nmatch >= 2) {
	acle = (aent_t *) malloc(sizeof(aent_t));
	if (acle) {
	    acle->ae_next = (aent_t *) NULL;
	    acle->ae_op_allowed = (krb5_int32) 0;
	    acle->ae_target =
		(nmatch >= 3) ? strdup(acle_object) : (char *) NULL;
	    acle->ae_target_bad = 0;
	    acle->ae_target_princ = (krb5_principal) NULL;
	    opok = 1;
	    for (op=acle_ops; *op; op++) {
		char rop;

		rop = (isupper(*op)) ? tolower(*op) : *op;
		found = 0;
		for (t=0; acl_op_table[t].ao_op; t++) {
		    if (rop == acl_op_table[t].ao_op) {
			found = 1;
			if (rop == *op)
			    acle->ae_op_allowed |= acl_op_table[t].ao_mask;
			else
			    acle->ae_op_allowed &= ~acl_op_table[t].ao_mask;
		    }
		}
		if (!found) {
		    krb5_klog_syslog(LOG_ERR, acl_op_bad_msg, *op, lp);
		    opok = 0;
		}
	    }
	    if (opok) {
		acle->ae_name = (char *) malloc(strlen(acle_principal)+1);
		if (acle->ae_name) {
		    strcpy(acle->ae_name, acle_principal);
		    acle->ae_principal = (krb5_principal) NULL;
		    acle->ae_name_bad = 0;
		    DPRINT(DEBUG_ACL, acl_debug_level,
			   ("A ACL entry %s -> opmask %x\n",
			    acle->ae_name, acle->ae_op_allowed));
		}
		else {
		    if (acle->ae_target)
			free(acle->ae_target);
		    free(acle);
		    acle = (aent_t *) NULL;
		}
	    }
	    else {
		if (acle->ae_target)
		    free(acle->ae_target);
		free(acle);
		acle = (aent_t *) NULL;
	    }
	}
    }
    DPRINT(DEBUG_CALLS, acl_debug_level,
	   ("X acl_parse_line() = %x\n", (long) acle));
    return(acle);
}

/*
 * acl_free_entries()	- Free all ACL entries.
 */
static void
acl_free_entries()
{
    aent_t	*ap;
    aent_t	*np;

    DPRINT(DEBUG_CALLS, acl_debug_level, ("* acl_free_entries()\n"));
    for (ap=acl_list_head; ap; ap = np) {
	if (ap->ae_name)
	    free(ap->ae_name);
	if (ap->ae_principal)
	    krb5_free_principal((krb5_context) NULL, ap->ae_principal);
	if (ap->ae_target)
	    free(ap->ae_target);
	if (ap->ae_target_princ)
	    krb5_free_principal((krb5_context) NULL, ap->ae_target_princ);
	np = ap->ae_next;
	free(ap);
    }
    acl_list_head = acl_list_tail = (aent_t *) NULL;
    acl_inited = 0;
    DPRINT(DEBUG_CALLS, acl_debug_level, ("X acl_free_entries()\n"));
}

/*
 * acl_load_acl_file()	- Open and parse the ACL file.
 */
static int
acl_load_acl_file()
{
char tmpbuf[10];
    FILE 	*afp;
    char 	*alinep;
    aent_t	**aentpp;
    int		alineno;
    int		retval = 1;

    DPRINT(DEBUG_CALLS, acl_debug_level, ("* acl_load_acl_file()\n"));
    /* Open the ACL file for read */
    if (afp = fopen(acl_acl_file, "r")) {
	alineno = 1;
	aentpp = &acl_list_head;

	/* Get a non-comment line */
	while (alinep = acl_get_line(afp, &alineno)) {
	    /* Parse it */
	    *aentpp = acl_parse_line(alinep);
	    /* If syntax error, then fall out */
	    if (!*aentpp) {
		krb5_klog_syslog(LOG_ERR, acl_syn_err_msg,
			acl_acl_file, alineno, alinep);
		retval = 0;
		break;
	    }
	    acl_list_tail = *aentpp;
	    aentpp = &(*aentpp)->ae_next;
	}

	fclose(afp);

	if (acl_catchall_entry) {
	     strcpy(tmpbuf, acl_catchall_entry);
	     if (*aentpp = acl_parse_line(tmpbuf)) {
		  acl_list_tail = *aentpp;
	     }
	     else {
		  retval = 0;
		  DPRINT(DEBUG_OPERATION, acl_debug_level,
			 ("> catchall acl entry (%s) load failed\n",
			  acl_catchall_entry));
	     }
	}
    }
    else {
	krb5_klog_syslog(LOG_ERR, acl_cantopen_msg,
			 error_message(errno), acl_acl_file);
	if (acl_catchall_entry &&
	    (acl_list_head = acl_parse_line(acl_catchall_entry))) {
	    acl_list_tail = acl_list_head;
	}
	else {
	    retval = 0;
	    DPRINT(DEBUG_OPERATION, acl_debug_level,
		   ("> catchall acl entry (%s) load failed\n",
		    acl_catchall_entry));
	}
    }

    if (!retval) {
	acl_free_entries();
    }
    DPRINT(DEBUG_CALLS, acl_debug_level,
	   ("X acl_load_acl_file() = %d\n", retval));
    return(retval);
}

/*
 * acl_match_data()	- See if two data entries match.
 *
 * Wildcarding is only supported for a whole component.
 */
static krb5_boolean
acl_match_data(e1, e2)
    krb5_data	*e1, *e2;
{
    krb5_boolean	retval;

    DPRINT(DEBUG_CALLS, acl_debug_level, 
	   ("* acl_match_entry(%s, %s)\n", e1->data, e2->data));
    retval = 0;
    if (!strncmp(e1->data, "*", e1->length) ||
	!strncmp(e2->data, "*", e2->length)) {
	retval = 1;
    }
    else {
	if ((e1->length == e2->length) &&
	    (!strncmp(e1->data, e2->data, e1->length)))
	    retval = 1;
    }
    DPRINT(DEBUG_CALLS, acl_debug_level, ("X acl_match_entry()=%d\n",retval));
    return(retval);
}

/*
 * acl_find_entry()	- Find a matching entry.
 */
static aent_t *
acl_find_entry(kcontext, principal, dest_princ)
    krb5_context	kcontext;
    krb5_principal	principal;
    krb5_principal	dest_princ;
{
    aent_t		*entry;
    krb5_error_code	kret;
    int			i;
    int			matchgood;

    DPRINT(DEBUG_CALLS, acl_debug_level, ("* acl_find_entry()\n"));
    for (entry=acl_list_head; entry; entry = entry->ae_next) {
	if (!strcmp(entry->ae_name, "*")) {
	    DPRINT(DEBUG_ACL, acl_debug_level, ("A wildcard ACL match\n"));
	    break;
	}
	if (!entry->ae_principal && !entry->ae_name_bad) {
	    kret = krb5_parse_name(kcontext,
				   entry->ae_name,
				   &entry->ae_principal);
	    if (kret)
		entry->ae_name_bad = 1;
	}
	if (entry->ae_name_bad) {
	    DPRINT(DEBUG_ACL, acl_debug_level,
		   ("A Bad ACL entry %s\n", entry->ae_name));
	    continue;
	}
	if (entry->ae_target &&
	    !entry->ae_target_princ &&
	    !entry->ae_target_bad) {
	    kret = krb5_parse_name(kcontext,
				   entry->ae_target,
				   &entry->ae_target_princ);
	    if (kret)
		entry->ae_target_bad = 1;
	}
	if (entry->ae_target_bad) {
	    DPRINT(DEBUG_ACL, acl_debug_level,
		   ("A Bad target in an ACL entry for %s\n", entry->ae_name));
	    entry->ae_name_bad = 1;
	    continue;
	}
	matchgood = 0;
	if (acl_match_data(&entry->ae_principal->realm,
			   &principal->realm) &&
	    (entry->ae_principal->length == principal->length)) {
	    matchgood = 1;
	    for (i=0; i<principal->length; i++) {
		if (!acl_match_data(&entry->ae_principal->data[i],
				    &principal->data[i])) {
		    matchgood = 0;
		    break;
		}
	    }
	}
	if (!matchgood)
	    continue;

	/* We've matched the principal.  If we have a target, then try it */
	if (entry->ae_target && entry->ae_target_princ && dest_princ) {
	    if (acl_match_data(&entry->ae_target_princ->realm,
			       &dest_princ->realm) &&
		(entry->ae_target_princ->length == dest_princ->length)) {
	       for (i=0; i<dest_princ->length; i++) {
		  if (!acl_match_data(&entry->ae_target_princ->data[i],
				      &dest_princ->data[i])) {
		     matchgood = 0;
		     break;
		  }
	       }
	    }
	    else
	       matchgood = 0;
	}

	if (matchgood)
	    break;
    }
    DPRINT(DEBUG_CALLS, acl_debug_level, ("X acl_find_entry()=%x\n",entry));
    return(entry);
}

/*
 * acl_init()	- Initialize ACL context.
 */
krb5_error_code
acl_init(kcontext, debug_level, acl_file)
    krb5_context	kcontext;
    int			debug_level;
    char		*acl_file;
{
    krb5_error_code	kret;

    kret = 0;
    acl_debug_level = debug_level;
    DPRINT(DEBUG_CALLS, acl_debug_level,
	   ("* acl_init(afile=%s)\n",
	    ((acl_file) ? acl_file : "(null)")));
    acl_acl_file = (acl_file) ? acl_file : (char *) KRB5_DEFAULT_ADMIN_ACL;
    acl_inited = acl_load_acl_file();

    DPRINT(DEBUG_CALLS, acl_debug_level, ("X acl_init() = %d\n", kret));
    return(kret);
}

/*
 * acl_finish	- Terminate ACL context.
 */
void
acl_finish(kcontext, debug_level)
    krb5_context	kcontext;
    int			debug_level;
{
    DPRINT(DEBUG_CALLS, acl_debug_level, ("* acl_finish()\n"));
    acl_free_entries();
    DPRINT(DEBUG_CALLS, acl_debug_level, ("X acl_finish()\n"));
}

/*
 * acl_op_permitted()	- Is this operation permitted for this principal?
 *			this code used not to be based on gssapi.  In order
 *			to minimize porting hassles, I've put all the
 *			gssapi hair in this function.  This might not be
 *			the best medium-term solution.  (The best long-term
 *			solution is, of course, a real authorization service.)
 */
krb5_boolean
acl_check(kcontext, caller, opmask, principal)
    krb5_context	kcontext;
    gss_name_t		caller;
    krb5_int32		opmask;
    krb5_principal	principal;
{
    krb5_boolean	retval;
    aent_t		*aentry;
    gss_buffer_desc	caller_buf;
    gss_OID		caller_oid;
    OM_uint32		emaj, emin;
    krb5_error_code	code;
    krb5_principal	caller_princ;

    DPRINT(DEBUG_CALLS, acl_debug_level, ("* acl_op_permitted()\n"));

    if (GSS_ERROR(emaj = gss_display_name(&emin, caller, &caller_buf,
					  &caller_oid)))
       return(0);

    code = krb5_parse_name(kcontext, (char *) caller_buf.value,
			   &caller_princ);

    gss_release_buffer(&emin, &caller_buf);

    if (code)
       return(code);

    retval = 0;
    if (aentry = acl_find_entry(kcontext, caller_princ, principal)) {
	if ((aentry->ae_op_allowed & opmask) == opmask)
	    retval = 1;
    }

    krb5_free_principal(kcontext, caller_princ);

    DPRINT(DEBUG_CALLS, acl_debug_level, ("X acl_op_permitted()=%d\n",
					  retval));
    return(retval);
}

kadm5_ret_t kadm5_get_privs(void *server_handle, long *privs)
{
     kadm5_server_handle_t handle = server_handle;

     CHECK_HANDLE(server_handle);

     /* this is impossible to do with the current interface.  For now,
	return all privs, which will confuse some clients, but not
	deny any access to users of "smart" clients which try to cache */

     *privs = ~0;

     return KADM5_OK;
}