Commit message: Do bounds checking when unescaping PPP.

Clean up a const issue while we're at it.
CVE: CVE-2014-9140
CWE: CWE-119
Vulnerability description: Buffer overflow in the ppp_hdlc function in print-ppp.c in tcpdump 4.6.2 and earlier allows remote attackers to cause a denial of service (crash) cia a crafted PPP packet.

Project: tcpdump
File: print-ppp.c

handle_bap(netdissect_options *ndo _U_,
           const u_char *p _U_, int length _U_)
{
	/* XXX: to be supported!! */
}

Project: tcpdump
File: print-ppp.c

handle_chap(netdissect_options *ndo,
            const u_char *p, int length)
{
	u_int code, len;
	int val_size, name_size, msg_size;
	const u_char *p0;
	int i;

	p0 = p;
	if (length < 1) {
		ND_PRINT((ndo, "[|chap]"));
		return;
	} else if (length < 4) {
		ND_TCHECK(*p);
		ND_PRINT((ndo, "[|chap 0x%02x]", *p));
		return;
	}

	ND_TCHECK(*p);
	code = *p;
	ND_PRINT((ndo, "CHAP, %s (0x%02x)",
               tok2str(chapcode_values,"unknown",code),
               code));
	p++;

	ND_TCHECK(*p);
	ND_PRINT((ndo, ", id %u", *p));		/* ID */
	p++;

	ND_TCHECK2(*p, 2);
	len = EXTRACT_16BITS(p);
	p += 2;

	/*
	 * Note that this is a generic CHAP decoding routine. Since we
	 * don't know which flavor of CHAP (i.e. CHAP-MD5, MS-CHAPv1,
	 * MS-CHAPv2) is used at this point, we can't decode packet
	 * specifically to each algorithms. Instead, we simply decode
	 * the GCD (Gratest Common Denominator) for all algorithms.
	 */
	switch (code) {
	case CHAP_CHAL:
	case CHAP_RESP:
		if (length - (p - p0) < 1)
			return;
		ND_TCHECK(*p);
		val_size = *p;		/* value size */
		p++;
		if (length - (p - p0) < val_size)
			return;
		ND_PRINT((ndo, ", Value "));
		for (i = 0; i < val_size; i++) {
			ND_TCHECK(*p);
			ND_PRINT((ndo, "%02x", *p++));
		}
		name_size = len - (p - p0);
		ND_PRINT((ndo, ", Name "));
		for (i = 0; i < name_size; i++) {
			ND_TCHECK(*p);
			safeputchar(ndo, *p++);
		}
		break;
	case CHAP_SUCC:
	case CHAP_FAIL:
		msg_size = len - (p - p0);
		ND_PRINT((ndo, ", Msg "));
		for (i = 0; i< msg_size; i++) {
			ND_TCHECK(*p);
			safeputchar(ndo, *p++);
		}
		break;
	}
	return;

trunc:
	ND_PRINT((ndo, "[|chap]"));
}

Project: tcpdump
File: print-ppp.c

handle_ctrl_proto(netdissect_options *ndo,
                  u_int proto, const u_char *pptr, int length)
{
	const char *typestr;
	u_int code, len;
	int (*pfunc)(netdissect_options *, const u_char *, int);
	int x, j;
        const u_char *tptr;

        tptr=pptr;

        typestr = tok2str(ppptype2str, "unknown ctrl-proto (0x%04x)", proto);
	ND_PRINT((ndo, "%s, ", typestr));

	if (length < 4) /* FIXME weak boundary checking */
		goto trunc;
	ND_TCHECK2(*tptr, 2);

	code = *tptr++;

	ND_PRINT((ndo, "%s (0x%02x), id %u, length %u",
	          tok2str(cpcodes, "Unknown Opcode",code),
	          code,
	          *tptr++, /* ID */
	          length + 2));

	if (!ndo->ndo_vflag)
		return;

	if (length <= 4)
		return;    /* there may be a NULL confreq etc. */

	ND_TCHECK2(*tptr, 2);
	len = EXTRACT_16BITS(tptr);
	tptr += 2;

	ND_PRINT((ndo, "\n\tencoded length %u (=Option(s) length %u)", len, len - 4));

	if (ndo->ndo_vflag > 1)
		print_unknown_data(ndo, pptr - 2, "\n\t", 6);


	switch (code) {
	case CPCODES_VEXT:
		if (length < 11)
			break;
		ND_TCHECK2(*tptr, 4);
		ND_PRINT((ndo, "\n\t  Magic-Num 0x%08x", EXTRACT_32BITS(tptr)));
		tptr += 4;
		ND_TCHECK2(*tptr, 3);
		ND_PRINT((ndo, " Vendor: %s (%u)",
                       tok2str(oui_values,"Unknown",EXTRACT_24BITS(tptr)),
                       EXTRACT_24BITS(tptr)));
		/* XXX: need to decode Kind and Value(s)? */
		break;
	case CPCODES_CONF_REQ:
	case CPCODES_CONF_ACK:
	case CPCODES_CONF_NAK:
	case CPCODES_CONF_REJ:
		x = len - 4;	/* Code(1), Identifier(1) and Length(2) */
		do {
			switch (proto) {
			case PPP_LCP:
				pfunc = print_lcp_config_options;
				break;
			case PPP_IPCP:
				pfunc = print_ipcp_config_options;
				break;
			case PPP_IPV6CP:
				pfunc = print_ip6cp_config_options;
				break;
			case PPP_CCP:
				pfunc = print_ccp_config_options;
				break;
			case PPP_BACP:
				pfunc = print_bacp_config_options;
				break;
			default:
				/*
				 * No print routine for the options for
				 * this protocol.
				 */
				pfunc = NULL;
				break;
			}

			if (pfunc == NULL) /* catch the above null pointer if unknown CP */
				break;

			if ((j = (*pfunc)(ndo, tptr, len)) == 0)
				break;
			x -= j;
			tptr += j;
		} while (x > 0);
		break;

	case CPCODES_TERM_REQ:
	case CPCODES_TERM_ACK:
		/* XXX: need to decode Data? */
		break;
	case CPCODES_CODE_REJ:
		/* XXX: need to decode Rejected-Packet? */
		break;
	case CPCODES_PROT_REJ:
		if (length < 6)
			break;
		ND_TCHECK2(*tptr, 2);
		ND_PRINT((ndo, "\n\t  Rejected %s Protocol (0x%04x)",
		       tok2str(ppptype2str,"unknown", EXTRACT_16BITS(tptr)),
		       EXTRACT_16BITS(tptr)));
		/* XXX: need to decode Rejected-Information? - hexdump for now */
		if (len > 6) {
			ND_PRINT((ndo, "\n\t  Rejected Packet"));
			print_unknown_data(ndo, tptr + 2, "\n\t    ", len - 2);
		}
		break;
	case CPCODES_ECHO_REQ:
	case CPCODES_ECHO_RPL:
	case CPCODES_DISC_REQ:
		if (length < 8)
			break;
		ND_TCHECK2(*tptr, 4);
		ND_PRINT((ndo, "\n\t  Magic-Num 0x%08x", EXTRACT_32BITS(tptr)));
		/* XXX: need to decode Data? - hexdump for now */
		if (len > 8) {
			ND_PRINT((ndo, "\n\t  -----trailing data-----"));
			ND_TCHECK2(tptr[4], len - 8);
			print_unknown_data(ndo, tptr + 4, "\n\t  ", len - 8);
		}
		break;
	case CPCODES_ID:
		if (length < 8)
			break;
		ND_TCHECK2(*tptr, 4);
		ND_PRINT((ndo, "\n\t  Magic-Num 0x%08x", EXTRACT_32BITS(tptr)));
		/* RFC 1661 says this is intended to be human readable */
		if (len > 8) {
			ND_PRINT((ndo, "\n\t  Message\n\t    "));
			if (fn_printn(ndo, tptr + 4, len - 4, ndo->ndo_snapend))
				goto trunc;
		}
		break;
	case CPCODES_TIME_REM:
		if (length < 12)
			break;
		ND_TCHECK2(*tptr, 4);
		ND_PRINT((ndo, "\n\t  Magic-Num 0x%08x", EXTRACT_32BITS(tptr)));
		ND_TCHECK2(*(tptr + 4), 4);
		ND_PRINT((ndo, ", Seconds-Remaining %us", EXTRACT_32BITS(tptr + 4)));
		/* XXX: need to decode Message? */
		break;
	default:
		/* XXX this is dirty but we do not get the
		 * original pointer passed to the begin
		 * the PPP packet */
		if (ndo->ndo_vflag <= 1)
			print_unknown_data(ndo, pptr - 2, "\n\t  ", length + 2);
		break;
	}
	return;

trunc:
	ND_PRINT((ndo, "[|%s]", typestr));
}

Project: tcpdump
File: print-ppp.c

ppp_bsdos_if_print(netdissect_options *ndo _U_,
                   const struct pcap_pkthdr *h _U_, register const u_char *p _U_)
{
	register int hdrlength;
#ifdef __bsdi__
	register u_int length = h->len;
	register u_int caplen = h->caplen;
	uint16_t ptype;
	const u_char *q;
	int i;

	if (caplen < PPP_BSDI_HDRLEN) {
		ND_PRINT((ndo, "[|ppp]"));
		return (caplen)
	}

	hdrlength = 0;

#if 0
	if (p[0] == PPP_ADDRESS && p[1] == PPP_CONTROL) {
		if (ndo->ndo_eflag)
			ND_PRINT((ndo, "%02x %02x ", p[0], p[1]));
		p += 2;
		hdrlength = 2;
	}

	if (ndo->ndo_eflag)
		ND_PRINT((ndo, "%d ", length));
	/* Retrieve the protocol type */
	if (*p & 01) {
		/* Compressed protocol field */
		ptype = *p;
		if (ndo->ndo_eflag)
			ND_PRINT((ndo, "%02x ", ptype));
		p++;
		hdrlength += 1;
	} else {
		/* Un-compressed protocol field */
		ptype = EXTRACT_16BITS(p);
		if (ndo->ndo_eflag)
			ND_PRINT((ndo, "%04x ", ptype));
		p += 2;
		hdrlength += 2;
	}
#else
	ptype = 0;	/*XXX*/
	if (ndo->ndo_eflag)
		ND_PRINT((ndo, "%c ", p[SLC_DIR] ? 'O' : 'I'));
	if (p[SLC_LLHL]) {
		/* link level header */
		struct ppp_header *ph;

		q = p + SLC_BPFHDRLEN;
		ph = (struct ppp_header *)q;
		if (ph->phdr_addr == PPP_ADDRESS
		 && ph->phdr_ctl == PPP_CONTROL) {
			if (ndo->ndo_eflag)
				ND_PRINT((ndo, "%02x %02x ", q[0], q[1]));
			ptype = EXTRACT_16BITS(&ph->phdr_type);
			if (ndo->ndo_eflag && (ptype == PPP_VJC || ptype == PPP_VJNC)) {
				ND_PRINT((ndo, "%s ", tok2str(ppptype2str,
						"proto-#%d", ptype)));
			}
		} else {
			if (ndo->ndo_eflag) {
				ND_PRINT((ndo, "LLH=["));
				for (i = 0; i < p[SLC_LLHL]; i++)
					ND_PRINT((ndo, "%02x", q[i]));
				ND_PRINT((ndo, "] "));
			}
		}
	}
	if (ndo->ndo_eflag)
		ND_PRINT((ndo, "%d ", length));
	if (p[SLC_CHL]) {
		q = p + SLC_BPFHDRLEN + p[SLC_LLHL];

		switch (ptype) {
		case PPP_VJC:
			ptype = vjc_print(ndo, q, ptype);
			hdrlength = PPP_BSDI_HDRLEN;
			p += hdrlength;
			switch (ptype) {
			case PPP_IP:
				ip_print(ndo, p, length);
				break;
			case PPP_IPV6:
				ip6_print(ndo, p, length);
				break;
			case PPP_MPLS_UCAST:
			case PPP_MPLS_MCAST:
				mpls_print(ndo, p, length);
				break;
			}
			goto printx;
		case PPP_VJNC:
			ptype = vjc_print(ndo, q, ptype);
			hdrlength = PPP_BSDI_HDRLEN;
			p += hdrlength;
			switch (ptype) {
			case PPP_IP:
				ip_print(ndo, p, length);
				break;
			case PPP_IPV6:
				ip6_print(ndo, p, length);
				break;
			case PPP_MPLS_UCAST:
			case PPP_MPLS_MCAST:
				mpls_print(ndo, p, length);
				break;
			}
			goto printx;
		default:
			if (ndo->ndo_eflag) {
				ND_PRINT((ndo, "CH=["));
				for (i = 0; i < p[SLC_LLHL]; i++)
					ND_PRINT((ndo, "%02x", q[i]));
				ND_PRINT((ndo, "] "));
			}
			break;
		}
	}

	hdrlength = PPP_BSDI_HDRLEN;
#endif

	length -= hdrlength;
	p += hdrlength;

	switch (ptype) {
	case PPP_IP:
		ip_print(p, length);
		break;
	case PPP_IPV6:
		ip6_print(ndo, p, length);
		break;
	case PPP_MPLS_UCAST:
	case PPP_MPLS_MCAST:
		mpls_print(ndo, p, length);
		break;
	default:
		ND_PRINT((ndo, "%s ", tok2str(ppptype2str, "unknown PPP protocol (0x%04x)", ptype)));
	}

printx:
#else /* __bsdi */
	hdrlength = 0;
#endif /* __bsdi__ */
	return (hdrlength);
}

Project: tcpdump
File: print-ppp.c

ppp_hdlc_if_print(netdissect_options *ndo,
                  const struct pcap_pkthdr *h, register const u_char *p)
{
	register u_int length = h->len;
	register u_int caplen = h->caplen;
	u_int proto;
	u_int hdrlen = 0;

	if (caplen < 2) {
		ND_PRINT((ndo, "[|ppp]"));
		return (caplen);
	}

	switch (p[0]) {

	case PPP_ADDRESS:
		if (caplen < 4) {
			ND_PRINT((ndo, "[|ppp]"));
			return (caplen);
		}

		if (ndo->ndo_eflag)
			ND_PRINT((ndo, "%02x %02x %d ", p[0], p[1], length));
		p += 2;
		length -= 2;
		hdrlen += 2;

		proto = EXTRACT_16BITS(p);
		p += 2;
		length -= 2;
		hdrlen += 2;
		ND_PRINT((ndo, "%s: ", tok2str(ppptype2str, "unknown PPP protocol (0x%04x)", proto)));

		handle_ppp(ndo, proto, p, length);
		break;

	case CHDLC_UNICAST:
	case CHDLC_BCAST:
		return (chdlc_if_print(ndo, h, p));

	default:
		if (ndo->ndo_eflag)
			ND_PRINT((ndo, "%02x %02x %d ", p[0], p[1], length));
		p += 2;
		hdrlen += 2;

		/*
		 * XXX - NetBSD's "ppp_netbsd_serial_if_print()" treats
		 * the next two octets as an Ethernet type; does that
		 * ever happen?
		 */
		ND_PRINT((ndo, "unknown addr %02x; ctrl %02x", p[0], p[1]));
		break;
	}

	return (hdrlen);
}

Project: tcpdump
File: print-ppp.c

ppp_if_print(netdissect_options *ndo,
             const struct pcap_pkthdr *h, register const u_char *p)
{
	register u_int length = h->len;
	register u_int caplen = h->caplen;

	if (caplen < PPP_HDRLEN) {
		ND_PRINT((ndo, "[|ppp]"));
		return (caplen);
	}

#if 0
	/*
	 * XXX: seems to assume that there are 2 octets prepended to an
	 * actual PPP frame. The 1st octet looks like Input/Output flag
	 * while 2nd octet is unknown, at least to me
	 * (mshindo@mshindo.net).
	 *
	 * That was what the original tcpdump code did.
	 *
	 * FreeBSD's "if_ppp.c" *does* set the first octet to 1 for outbound
	 * packets and 0 for inbound packets - but only if the
	 * protocol field has the 0x8000 bit set (i.e., it's a network
	 * control protocol); it does so before running the packet through
	 * "bpf_filter" to see if it should be discarded, and to see
	 * if we should update the time we sent the most recent packet...
	 *
	 * ...but it puts the original address field back after doing
	 * so.
	 *
	 * NetBSD's "if_ppp.c" doesn't set the first octet in that fashion.
	 *
	 * I don't know if any PPP implementation handed up to a BPF
	 * device packets with the first octet being 1 for outbound and
	 * 0 for inbound packets, so I (guy@alum.mit.edu) don't know
	 * whether that ever needs to be checked or not.
	 *
	 * Note that NetBSD has a DLT_PPP_SERIAL, which it uses for PPP,
	 * and its tcpdump appears to assume that the frame always
	 * begins with an address field and a control field, and that
	 * the address field might be 0x0f or 0x8f, for Cisco
	 * point-to-point with HDLC framing as per section 4.3.1 of RFC
	 * 1547, as well as 0xff, for PPP in HDLC-like framing as per
	 * RFC 1662.
	 *
	 * (Is the Cisco framing in question what DLT_C_HDLC, in
	 * BSD/OS, is?)
	 */
	if (ndo->ndo_eflag)
		ND_PRINT((ndo, "%c %4d %02x ", p[0] ? 'O' : 'I', length, p[1]));
#endif

	ppp_print(ndo, p, length);

	return (0);
}

Project: tcpdump
File: print-ppp.c

ppp_print(netdissect_options *ndo,
          register const u_char *p, u_int length)
{
	u_int proto,ppp_header;
        u_int olen = length; /* _o_riginal length */
	u_int hdr_len = 0;

	/*
	 * Here, we assume that p points to the Address and Control
	 * field (if they present).
	 */
	if (length < 2)
		goto trunc;
	ND_TCHECK2(*p, 2);
        ppp_header = EXTRACT_16BITS(p);

        switch(ppp_header) {
        case (PPP_WITHDIRECTION_IN  << 8 | PPP_CONTROL):
            if (ndo->ndo_eflag) ND_PRINT((ndo, "In  "));
            p += 2;
            length -= 2;
            hdr_len += 2;
            break;
        case (PPP_WITHDIRECTION_OUT << 8 | PPP_CONTROL):
            if (ndo->ndo_eflag) ND_PRINT((ndo, "Out "));
            p += 2;
            length -= 2;
            hdr_len += 2;
            break;
        case (PPP_ADDRESS << 8 | PPP_CONTROL):
            p += 2;			/* ACFC not used */
            length -= 2;
            hdr_len += 2;
            break;

        default:
            break;
        }

	if (length < 2)
		goto trunc;
	ND_TCHECK(*p);
	if (*p % 2) {
		proto = *p;		/* PFC is used */
		p++;
		length--;
		hdr_len++;
	} else {
		ND_TCHECK2(*p, 2);
		proto = EXTRACT_16BITS(p);
		p += 2;
		length -= 2;
		hdr_len += 2;
	}

	if (ndo->ndo_eflag)
		ND_PRINT((ndo, "%s (0x%04x), length %u: ",
		          tok2str(ppptype2str, "unknown", proto),
		          proto,
		          olen));

	handle_ppp(ndo, proto, p, length);
	return (hdr_len);
trunc:
	ND_PRINT((ndo, "[|ppp]"));
	return (0);
}

Project: tcpdump
File: print-ppp.c

print_ccp_config_options(netdissect_options *ndo,
                         const u_char *p, int length)
{
	int len, opt;

	if (length < 2)
		return 0;
	ND_TCHECK2(*p, 2);
	len = p[1];
	opt = p[0];
	if (length < len)
		return 0;
	if (len < 2) {
		ND_PRINT((ndo, "\n\t  %s Option (0x%02x), length %u (length bogus, should be >= 2)",
		          tok2str(ccpconfopts_values, "Unknown", opt),
		          opt,
		          len));
		return 0;
	}

	ND_PRINT((ndo, "\n\t  %s Option (0x%02x), length %u",
	          tok2str(ccpconfopts_values, "Unknown", opt),
	          opt,
	          len));

	switch (opt) {
	case CCPOPT_BSDCOMP:
		if (len < 3) {
			ND_PRINT((ndo, " (length bogus, should be >= 3)"));
			return len;
		}
		ND_TCHECK2(*(p + 2), 1);
		ND_PRINT((ndo, ": Version: %u, Dictionary Bits: %u",
			p[2] >> 5, p[2] & 0x1f));
		break;
	case CCPOPT_MVRCA:
		if (len < 4) {
			ND_PRINT((ndo, " (length bogus, should be >= 4)"));
			return len;
		}
		ND_TCHECK2(*(p + 2), 1);
		ND_PRINT((ndo, ": Features: %u, PxP: %s, History: %u, #CTX-ID: %u",
				(p[2] & 0xc0) >> 6,
				(p[2] & 0x20) ? "Enabled" : "Disabled",
				p[2] & 0x1f, p[3]));
		break;
	case CCPOPT_DEFLATE:
		if (len < 4) {
			ND_PRINT((ndo, " (length bogus, should be >= 4)"));
			return len;
		}
		ND_TCHECK2(*(p + 2), 1);
		ND_PRINT((ndo, ": Window: %uK, Method: %s (0x%x), MBZ: %u, CHK: %u",
			(p[2] & 0xf0) >> 4,
			((p[2] & 0x0f) == 8) ? "zlib" : "unkown",
			p[2] & 0x0f, (p[3] & 0xfc) >> 2, p[3] & 0x03));
		break;

/* XXX: to be supported */
#if 0
	case CCPOPT_OUI:
	case CCPOPT_PRED1:
	case CCPOPT_PRED2:
	case CCPOPT_PJUMP:
	case CCPOPT_HPPPC:
	case CCPOPT_STACLZS:
	case CCPOPT_MPPC:
	case CCPOPT_GFZA:
	case CCPOPT_V42BIS:
	case CCPOPT_LZSDCP:
	case CCPOPT_DEC:
	case CCPOPT_RESV:
		break;
#endif
	default:
		/*
		 * Unknown option; dump it as raw bytes now if we're
		 * not going to do so below.
		 */
		if (ndo->ndo_vflag < 2)
			print_unknown_data(ndo, &p[2], "\n\t    ", len - 2);
		break;
	}
	if (ndo->ndo_vflag > 1)
		print_unknown_data(ndo, &p[2], "\n\t    ", len - 2); /* exclude TLV header */

	return len;

trunc:
	ND_PRINT((ndo, "[|ccp]"));
	return 0;
}

Project: tcpdump
File: print-ppp.c

print_ip6cp_config_options(netdissect_options *ndo,
                           const u_char *p, int length)
{
	int len, opt;

	if (length < 2)
		return 0;
	ND_TCHECK2(*p, 2);
	len = p[1];
	opt = p[0];
	if (length < len)
		return 0;
	if (len < 2) {
		ND_PRINT((ndo, "\n\t  %s Option (0x%02x), length %u (length bogus, should be >= 2)",
		       tok2str(ip6cpopt_values,"unknown",opt),
		       opt,
		       len));
		return 0;
	}

	ND_PRINT((ndo, "\n\t  %s Option (0x%02x), length %u",
	       tok2str(ip6cpopt_values,"unknown",opt),
	       opt,
	       len));

	switch (opt) {
	case IP6CP_IFID:
		if (len != 10) {
			ND_PRINT((ndo, " (length bogus, should be = 10)"));
			return len;
		}
		ND_TCHECK2(*(p + 2), 8);
		ND_PRINT((ndo, ": %04x:%04x:%04x:%04x",
		       EXTRACT_16BITS(p + 2),
		       EXTRACT_16BITS(p + 4),
		       EXTRACT_16BITS(p + 6),
		       EXTRACT_16BITS(p + 8)));
		break;
	default:
		/*
		 * Unknown option; dump it as raw bytes now if we're
		 * not going to do so below.
		 */
		if (ndo->ndo_vflag < 2)
			print_unknown_data(ndo, &p[2], "\n\t    ", len - 2);
		break;
	}
	if (ndo->ndo_vflag > 1)
		print_unknown_data(ndo, &p[2], "\n\t    ", len - 2); /* exclude TLV header */

	return len;

trunc:
	ND_PRINT((ndo, "[|ip6cp]"));
	return 0;
}