538 lines
10 KiB
Plaintext
538 lines
10 KiB
Plaintext
/* $NetBSD: parse.y,v 1.10 2005/08/24 19:09:03 elad Exp $ */
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/* $OpenBSD: parse.y,v 1.9 2002/08/04 04:15:50 provos Exp $ */
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/*
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* Copyright 2002 Niels Provos <provos@citi.umich.edu>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Niels Provos.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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%{
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#include <sys/cdefs.h>
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__RCSID("$NetBSD: parse.y,v 1.10 2005/08/24 19:09:03 elad Exp $");
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#include <sys/types.h>
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#include <sys/time.h>
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#include <sys/tree.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <err.h>
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#include <stdarg.h>
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#include <string.h>
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#include <unistd.h>
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#include <pwd.h>
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#include <grp.h>
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#include <regex.h>
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#include "intercept.h"
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#include "systrace.h"
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#include "systrace-errno.h"
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#include "filter.h"
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void yyrestart(FILE *);
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struct logic *parse_newsymbol(char *, int, char *);
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int yylex(void);
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int yyparse(void);
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int yyerror(const char *, ...);
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int errors = 0;
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struct filter *myfilter;
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extern char *mystring;
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extern int myoff;
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extern int iamroot;
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%}
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%token AND OR NOT LBRACE RBRACE LSQBRACE RSQBRACE THEN MATCH PERMIT DENY ASK
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%token EQ NEQ TRUE SUB NSUB INPATH LOG COMMA IF USER GROUP EQUAL NEQUAL AS
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%token COLON RE LESSER GREATER TOPDIR
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%token <string> STRING
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%token <string> CMDSTRING
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%token <number> NUMBER
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%type <logic> expression
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%type <logic> symbol
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%type <action> action
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%type <number> typeoff
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%type <number> logcode
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%type <uid> uid
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%type <gid> gid
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%type <string> errorcode
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%type <predicate> predicate
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%type <elevate> elevate;
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%union {
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int number;
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char *string;
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short action;
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struct logic *logic;
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struct predicate predicate;
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struct elevate elevate;
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uid_t uid;
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gid_t gid;
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}
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%%
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fullexpression : expression THEN action errorcode logcode elevate predicate
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{
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int flags = 0, errorcode = SYSTRACE_EPERM;
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switch ($3) {
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case ICPOLICY_NEVER:
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if ($4 == NULL)
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break;
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errorcode = systrace_error_translate($4);
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if (errorcode == -1)
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yyerror("Unknown error code: %s", $4);
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break;
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case ICPOLICY_PERMIT:
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if ($4 == NULL)
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break;
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if (!strcasecmp($4, "inherit"))
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flags = PROCESS_INHERIT_POLICY;
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else if (!strcasecmp($4, "detach"))
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flags = PROCESS_DETACH;
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else
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yyerror("Unknown flag: %s", $4);
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break;
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}
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if ($5)
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flags |= SYSCALL_LOG;
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/* Special policy that allows only yes or no */
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if ($3 == ICPOLICY_ASK)
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flags |= PROCESS_PROMPT;
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if ($4 != NULL)
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free($4);
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myfilter = calloc(1, sizeof(struct filter));
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if (myfilter == NULL) {
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yyerror("calloc");
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break;
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}
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myfilter->logicroot = $1;
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myfilter->match_action = $3;
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myfilter->match_error = errorcode;
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myfilter->match_flags = flags;
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myfilter->match_predicate = $7;
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myfilter->elevate = $6;
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}
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;
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errorcode : /* Empty */
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{
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$$ = NULL;
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}
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| LSQBRACE STRING RSQBRACE
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{
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$$ = $2;
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}
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;
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logcode : /* Empty */
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{
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$$ = 0;
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}
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| LOG
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{
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$$ = 1;
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}
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;
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uid : NUMBER
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{
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$$ = $1;
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}
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| STRING
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{
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struct passwd *pw;
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if ((pw = getpwnam($1)) == NULL) {
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yyerror("Unknown user %s", $1);
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break;
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}
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$$ = pw->pw_uid;
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}
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gid : NUMBER
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{
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$$ = $1;
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}
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| STRING
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{
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struct group *gr;
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if ((gr = getgrnam($1)) == NULL) {
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yyerror("Unknown group %s", $1);
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break;
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}
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$$ = gr->gr_gid;
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}
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elevate: /* Empty */
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{
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memset(&$$, 0, sizeof($$));
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}
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| AS uid
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{
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if (!iamroot) {
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yyerror("Privilege elevation not allowed.");
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break;
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}
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$$.e_flags = ELEVATE_UID;
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$$.e_uid = $2;
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}
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| AS uid COLON gid
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{
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if (!iamroot) {
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yyerror("Privilege elevation not allowed.");
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break;
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}
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$$.e_flags = ELEVATE_UID|ELEVATE_GID;
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$$.e_uid = $2;
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$$.e_gid = $4;
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}
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| AS COLON gid
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{
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if (!iamroot) {
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yyerror("Privilege elevation not allowed.");
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break;
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}
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$$.e_flags = ELEVATE_GID;
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$$.e_gid = $3;
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}
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predicate : /* Empty */
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{
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memset(&$$, 0, sizeof($$));
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}
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| COMMA IF USER EQUAL uid
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{
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memset(&$$, 0, sizeof($$));
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$$.p_uid = $5;
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$$.p_flags = PREDIC_UID;
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}
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| COMMA IF USER NEQUAL uid
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{
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memset(&$$, 0, sizeof($$));
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$$.p_uid = $5;
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$$.p_flags = PREDIC_UID | PREDIC_NEGATIVE;
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}
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| COMMA IF USER LESSER uid
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{
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memset(&$$, 0, sizeof($$));
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$$.p_uid = $5;
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$$.p_flags = PREDIC_UID | PREDIC_LESSER;
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}
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| COMMA IF USER GREATER uid
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{
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memset(&$$, 0, sizeof($$));
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$$.p_uid = $5;
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$$.p_flags = PREDIC_UID | PREDIC_GREATER;
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}
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| COMMA IF GROUP EQUAL gid
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{
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memset(&$$, 0, sizeof($$));
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$$.p_gid = $5;
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$$.p_flags = PREDIC_GID;
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}
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| COMMA IF GROUP NEQUAL gid
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{
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memset(&$$, 0, sizeof($$));
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$$.p_gid = $5;
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$$.p_flags = PREDIC_GID | PREDIC_NEGATIVE;
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}
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| COMMA IF GROUP LESSER gid
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{
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memset(&$$, 0, sizeof($$));
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$$.p_gid = $5;
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$$.p_flags = PREDIC_GID | PREDIC_LESSER;
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}
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| COMMA IF GROUP GREATER gid
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{
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memset(&$$, 0, sizeof($$));
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$$.p_gid = $5;
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$$.p_flags = PREDIC_GID | PREDIC_GREATER;
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}
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expression : symbol
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{
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$$ = $1;
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}
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| NOT expression
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{
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struct logic *node;
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node = calloc(1, sizeof(struct logic));
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if (node == NULL) {
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yyerror("calloc");
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break;
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}
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node->op = LOGIC_NOT;
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node->left = $2;
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$$ = node;
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}
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| LBRACE expression RBRACE
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{
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$$ = $2;
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}
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| expression AND expression
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{
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struct logic *node;
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node = calloc(1, sizeof(struct logic));
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if (node == NULL) {
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yyerror("calloc");
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break;
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}
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node->op = LOGIC_AND;
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node->left = $1;
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node->right = $3;
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$$ = node;
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}
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| expression OR expression
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{
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struct logic *node;
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node = calloc(1, sizeof(struct logic));
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if (node == NULL) {
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yyerror("calloc");
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break;
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}
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node->op = LOGIC_OR;
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node->left = $1;
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node->right = $3;
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$$ = node;
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}
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;
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symbol : STRING typeoff MATCH CMDSTRING
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{
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struct logic *node;
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if ((node = parse_newsymbol($1, $2, $4)) == NULL)
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break;
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node->filter_match = filter_fnmatch;
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$$ = node;
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}
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| STRING typeoff EQ CMDSTRING
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{
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struct logic *node;
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if ((node = parse_newsymbol($1, $2, $4)) == NULL)
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break;
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node->filter_match = filter_stringmatch;
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$$ = node;
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}
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| STRING typeoff NEQ CMDSTRING
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{
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struct logic *node;
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if ((node = parse_newsymbol($1, $2, $4)) == NULL)
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break;
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node->filter_match = filter_negstringmatch;
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$$ = node;
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}
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| STRING typeoff SUB CMDSTRING
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{
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struct logic *node;
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if ((node = parse_newsymbol($1, $2, $4)) == NULL)
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break;
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node->filter_match = filter_substrmatch;
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$$ = node;
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}
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| STRING typeoff NSUB CMDSTRING
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{
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struct logic *node;
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if ((node = parse_newsymbol($1, $2, $4)) == NULL)
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break;
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node->filter_match = filter_negsubstrmatch;
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$$ = node;
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}
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| STRING typeoff INPATH CMDSTRING
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{
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struct logic *node;
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if ((node = parse_newsymbol($1, $2, $4)) == NULL)
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break;
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node->filter_match = filter_inpath;
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$$ = node;
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}
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| STRING typeoff TOPDIR CMDSTRING
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{
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struct logic *node;
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if ((node = parse_newsymbol($1, $2, $4)) == NULL)
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break;
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node->filter_match = filter_topdir;
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$$ = node;
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}
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| STRING typeoff RE CMDSTRING
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{
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struct logic *node;
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regex_t *re;
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if ((node = parse_newsymbol($1, $2, $4)) == NULL)
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break;
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if ((re = calloc(1, sizeof (regex_t))) == NULL) {
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yyerror("calloc");
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break;
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}
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/* Precompute regexp here, otherwise we need to compute it
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* on the fly which is fairly expensive.
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*/
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if (!(node->flags & LOGIC_NEEDEXPAND)) {
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if (regcomp(re, node->filterdata,
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REG_EXTENDED | REG_NOSUB) != 0) {
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yyerror("Invalid regular expression: %s",
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node->filterdata);
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break;
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}
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node->filterarg = re;
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} else
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node->filterarg = NULL;
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node->filter_match = filter_regex;
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$$ = node;
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}
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| TRUE
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{
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struct logic *node;
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if ((node = parse_newsymbol(NULL, -1, NULL)) == NULL)
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break;
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node->filter_match = filter_true;
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$$ = node;
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}
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;
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typeoff : /* empty */
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{
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$$ = -1;
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}
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| LSQBRACE NUMBER RSQBRACE
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{
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if ($2 < 0 || $2 >= INTERCEPT_MAXSYSCALLARGS) {
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yyerror("Bad offset: %d", $2);
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break;
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}
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$$ = $2;
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}
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;
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action : PERMIT
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{
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$$ = ICPOLICY_PERMIT;
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}
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| ASK
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{
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$$ = ICPOLICY_ASK;
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}
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| DENY
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{
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$$ = ICPOLICY_NEVER;
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}
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%%
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int
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yyerror(const char *fmt, ...)
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{
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va_list ap;
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errors = 1;
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va_start(ap, fmt);
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vfprintf(stderr, fmt, ap);
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fprintf(stderr, "\n");
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va_end(ap);
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return (0);
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}
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struct logic *
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parse_newsymbol(char *type, int typeoff, char *data)
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{
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struct logic *node;
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node = calloc(1, sizeof(struct logic));
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if (node == NULL) {
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yyerror("calloc");
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return (NULL);
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}
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node->op = LOGIC_SINGLE;
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node->type = type;
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node->typeoff = typeoff;
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if (data) {
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/* For the root user, variable expansion may change */
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if (iamroot) {
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node->filterdata = data;
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if (filter_needexpand(data))
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node->flags |= LOGIC_NEEDEXPAND;
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} else {
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node->filterdata = strdup(filter_expand(data));
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free(data);
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}
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if (node->filterdata == NULL) {
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yyerror("strdup");
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return (NULL);
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}
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node->filterlen = strlen(node->filterdata) + 1;
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}
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return (node);
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}
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int
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parse_filter(char *name, struct filter **pfilter)
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{
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errors = 0;
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myfilter = NULL;
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mystring = name;
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myoff = 0;
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yyparse();
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yyrestart(NULL);
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*pfilter = myfilter;
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return (errors ? -1 : 0);
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}
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