taint.c 4.91 KB
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/*    taint.c
 *
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 *    Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,
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 *    2002, 2003, 2004, 2005, 2006, 2007, 2008 by Larry Wall and others
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 *
 *    You may distribute under the terms of either the GNU General Public
 *    License or the Artistic License, as specified in the README file.
 *
 */

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/*
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 * '...we will have peace, when you and all your works have perished--and
 *  the works of your dark master to whom you would deliver us.  You are a
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 *  liar, Saruman, and a corrupter of men's hearts.'       --Théoden
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 *
 *     [p.580 of _The Lord of the Rings_, III/x: "The Voice of Saruman"]
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 */

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/* This file contains a few functions for handling data tainting in Perl
 */

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#include "EXTERN.h"
#define PERL_IN_TAINT_C
#include "perl.h"

void
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Perl_taint_proper(pTHX_ const char *f, const char *const s)
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{
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#if defined(HAS_SETEUID) && defined(DEBUGGING)
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    dVAR;
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    PERL_ARGS_ASSERT_TAINT_PROPER;

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    {
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	const Uid_t  uid = PerlProc_getuid();
	const Uid_t euid = PerlProc_geteuid();
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	DEBUG_u(PerlIO_printf(Perl_debug_log,
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			       "%s %d %"Uid_t_f" %"Uid_t_f"\n",
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			       s, TAINT_get, uid, euid));
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    }
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#endif

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    if (TAINT_get) {
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	const char *ug;

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	if (!f)
	    f = PL_no_security;
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	if (PerlProc_getuid() != PerlProc_geteuid())
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	    ug = " while running setuid";
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	else if (PerlProc_getgid() != PerlProc_getegid())
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	    ug = " while running setgid";
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	else if (TAINT_WARN_get)
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            ug = " while running with -t switch";
        else
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	    ug = " while running with -T switch";
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        /* XXX because taint_proper adds extra format args, we can't
         * get the caller to check properly; o we just silence the warning
         * and hope the callers aren't naughty */
        GCC_DIAG_IGNORE(-Wformat-nonliteral);
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	if (PL_unsafe || TAINT_WARN_get) {
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	    Perl_ck_warner_d(aTHX_ packWARN(WARN_TAINT), f, s, ug);
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        }
        else {
            Perl_croak(aTHX_ f, s, ug);
        }
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        GCC_DIAG_RESTORE;

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    }
}

void
Perl_taint_env(pTHX)
{
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    dVAR;
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    SV** svp;
    MAGIC* mg;
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    const char* const *e;
    static const char* const misc_env[] = {
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	"IFS",		/* most shells' inter-field separators */
	"CDPATH",	/* ksh dain bramage #1 */
	"ENV",		/* ksh dain bramage #2 */
	"BASH_ENV",	/* bash dain bramage -- I guess it's contagious */
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#ifdef WIN32
	"PERL5SHELL",	/* used for system() on Windows */
#endif
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	NULL
    };

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    /* Don't bother if there's no *ENV glob */
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    if (!PL_envgv)
	return;
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    /* If there's no %ENV hash or if it's not magical, croak, because
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     * it probably doesn't reflect the actual environment */
    if (!GvHV(PL_envgv) || !(SvRMAGICAL(GvHV(PL_envgv))
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	    && mg_find((const SV *)GvHV(PL_envgv), PERL_MAGIC_env))) {
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	const bool was_tainted = TAINT_get;
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	const char * const name = GvENAME(PL_envgv);
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	TAINT;
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	if (strEQ(name,"ENV"))
	    /* hash alias */
	    taint_proper("%%ENV is aliased to %s%s", "another variable");
	else
	    /* glob alias: report it in the error message */
	    taint_proper("%%ENV is aliased to %%%s%s", name);
	/* this statement is reached under -t or -U */
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	TAINT_set(was_tainted);
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#ifdef NO_TAINT_SUPPORT
        PERL_UNUSED_VAR(was_tainted);
#endif
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    }
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#ifdef VMS
    {
    int i = 0;
    char name[10 + TYPE_DIGITS(int)] = "DCL$PATH";
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    STRLEN len = 8; /* strlen(name)  */
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    while (1) {
	if (i)
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	    len = my_sprintf(name,"DCL$PATH;%d", i);
	svp = hv_fetch(GvHVn(PL_envgv), name, len, FALSE);
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	if (!svp || *svp == &PL_sv_undef)
	    break;
	if (SvTAINTED(*svp)) {
	    TAINT;
	    taint_proper("Insecure %s%s", "$ENV{DCL$PATH}");
	}
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	if ((mg = mg_find(*svp, PERL_MAGIC_envelem)) && MgTAINTEDDIR(mg)) {
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	    TAINT;
	    taint_proper("Insecure directory in %s%s", "$ENV{DCL$PATH}");
	}
	i++;
    }
  }
#endif /* VMS */

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    svp = hv_fetchs(GvHVn(PL_envgv),"PATH",FALSE);
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    if (svp && *svp) {
	if (SvTAINTED(*svp)) {
	    TAINT;
	    taint_proper("Insecure %s%s", "$ENV{PATH}");
	}
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	if ((mg = mg_find(*svp, PERL_MAGIC_envelem)) && MgTAINTEDDIR(mg)) {
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	    TAINT;
	    taint_proper("Insecure directory in %s%s", "$ENV{PATH}");
	}
    }

#ifndef VMS
    /* tainted $TERM is okay if it contains no metachars */
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    svp = hv_fetchs(GvHVn(PL_envgv),"TERM",FALSE);
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    if (svp && *svp && SvTAINTED(*svp)) {
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	STRLEN len;
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	const bool was_tainted = TAINT_get;
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	const char *t = SvPV_const(*svp, len);
	const char * const e = t + len;
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	TAINT_set(was_tainted);
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#ifdef NO_TAINT_SUPPORT
        PERL_UNUSED_VAR(was_tainted);
#endif
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	if (t < e && isWORDCHAR(*t))
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	    t++;
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	while (t < e && (isWORDCHAR(*t) || strchr("-_.+", *t)))
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	    t++;
	if (t < e) {
	    TAINT;
	    taint_proper("Insecure $ENV{%s}%s", "TERM");
	}
    }
#endif /* !VMS */

    for (e = misc_env; *e; e++) {
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	SV * const * const svp = hv_fetch(GvHVn(PL_envgv), *e, strlen(*e), FALSE);
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	if (svp && *svp != &PL_sv_undef && SvTAINTED(*svp)) {
	    TAINT;
	    taint_proper("Insecure $ENV{%s}%s", *e);
	}
    }
}
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/*
 * Local variables:
 * c-indentation-style: bsd
 * c-basic-offset: 4
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 * indent-tabs-mode: nil
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 * End:
 *
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 * ex: set ts=8 sts=4 sw=4 et:
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 */