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tcpdump/print-stp.c
Guy Harris d9e65de3d9 CVE-2017-11108/Fix bounds checking for STP. 
Check whether the flags are in the captured data before printing them in
an MSTP BPDU.

Check whether V4 length is in the captured data before fetching it.
This fixes a vulnerability discovered by Kamil Frankowicz.

Include a test for the "check whether the V4 length is..." fix, using
the capture supplied by Kamil Frankowicz.
2017-07-22 23:57:42 +01:00

511 lines
17 KiB
C
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/*
* Copyright (c) 2000 Lennert Buytenhek
*
* This software may be distributed either under the terms of the
* BSD-style license that accompanies tcpdump or the GNU General
* Public License
*
* Contributed by Lennert Buytenhek <buytenh@gnu.org>
*/
/* \summary: IEEE 802.1d Spanning Tree Protocol (STP) printer */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <netdissect-stdinc.h>
#include <stdio.h>
#include "netdissect.h"
#include "extract.h"
#define RSTP_EXTRACT_PORT_ROLE(x) (((x)&0x0C)>>2)
/* STP timers are expressed in multiples of 1/256th second */
#define STP_TIME_BASE 256
#define STP_BPDU_MSTP_MIN_LEN 102
struct stp_bpdu_ {
uint8_t protocol_id[2];
uint8_t protocol_version;
uint8_t bpdu_type;
uint8_t flags;
uint8_t root_id[8];
uint8_t root_path_cost[4];
uint8_t bridge_id[8];
uint8_t port_id[2];
uint8_t message_age[2];
uint8_t max_age[2];
uint8_t hello_time[2];
uint8_t forward_delay[2];
uint8_t v1_length;
};
#define STP_PROTO_REGULAR 0x00
#define STP_PROTO_RAPID 0x02
#define STP_PROTO_MSTP 0x03
#define STP_PROTO_SPB 0x04
static const struct tok stp_proto_values[] = {
{ STP_PROTO_REGULAR, "802.1d" },
{ STP_PROTO_RAPID, "802.1w" },
{ STP_PROTO_MSTP, "802.1s" },
{ STP_PROTO_SPB, "802.1aq" },
{ 0, NULL}
};
#define STP_BPDU_TYPE_CONFIG 0x00
#define STP_BPDU_TYPE_RSTP 0x02
#define STP_BPDU_TYPE_TOPO_CHANGE 0x80
static const struct tok stp_bpdu_flag_values[] = {
{ 0x01, "Topology change" },
{ 0x02, "Proposal" },
{ 0x10, "Learn" },
{ 0x20, "Forward" },
{ 0x40, "Agreement" },
{ 0x80, "Topology change ACK" },
{ 0, NULL}
};
static const struct tok stp_bpdu_type_values[] = {
{ STP_BPDU_TYPE_CONFIG, "Config" },
{ STP_BPDU_TYPE_RSTP, "Rapid STP" },
{ STP_BPDU_TYPE_TOPO_CHANGE, "Topology Change" },
{ 0, NULL}
};
static const struct tok rstp_obj_port_role_values[] = {
{ 0x00, "Unknown" },
{ 0x01, "Alternate" },
{ 0x02, "Root" },
{ 0x03, "Designated" },
{ 0, NULL}
};
#define ND_TCHECK_BRIDGE_ID(p) ND_TCHECK2(*(p), 8)
static char *
stp_print_bridge_id(const u_char *p)
{
static char bridge_id_str[sizeof("pppp.aa:bb:cc:dd:ee:ff")];
snprintf(bridge_id_str, sizeof(bridge_id_str),
"%.2x%.2x.%.2x:%.2x:%.2x:%.2x:%.2x:%.2x",
p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7]);
return bridge_id_str;
}
static int
stp_print_config_bpdu(netdissect_options *ndo, const struct stp_bpdu_ *stp_bpdu,
u_int length)
{
ND_TCHECK(stp_bpdu->flags);
ND_PRINT((ndo, ", Flags [%s]",
bittok2str(stp_bpdu_flag_values, "none", stp_bpdu->flags)));
ND_TCHECK(stp_bpdu->port_id);
ND_PRINT((ndo, ", bridge-id %s.%04x, length %u",
stp_print_bridge_id((const u_char *)&stp_bpdu->bridge_id),
EXTRACT_16BITS(&stp_bpdu->port_id), length));
/* in non-verbose mode just print the bridge-id */
if (!ndo->ndo_vflag) {
return 1;
}
ND_TCHECK(stp_bpdu->forward_delay);
ND_PRINT((ndo, "\n\tmessage-age %.2fs, max-age %.2fs"
", hello-time %.2fs, forwarding-delay %.2fs",
(float)EXTRACT_16BITS(&stp_bpdu->message_age) / STP_TIME_BASE,
(float)EXTRACT_16BITS(&stp_bpdu->max_age) / STP_TIME_BASE,
(float)EXTRACT_16BITS(&stp_bpdu->hello_time) / STP_TIME_BASE,
(float)EXTRACT_16BITS(&stp_bpdu->forward_delay) / STP_TIME_BASE));
ND_PRINT((ndo, "\n\troot-id %s, root-pathcost %u",
stp_print_bridge_id((const u_char *)&stp_bpdu->root_id),
EXTRACT_32BITS(&stp_bpdu->root_path_cost)));
/* Port role is only valid for 802.1w */
if (stp_bpdu->protocol_version == STP_PROTO_RAPID) {
ND_PRINT((ndo, ", port-role %s",
tok2str(rstp_obj_port_role_values, "Unknown",
RSTP_EXTRACT_PORT_ROLE(stp_bpdu->flags))));
}
return 1;
trunc:
return 0;
}
/*
* MSTP packet format
* Ref. IEEE 802.1Q 2003 Ed. Section 14
*
* MSTP BPDU
*
* 2 - bytes Protocol Id
* 1 - byte Protocol Ver.
* 1 - byte BPDU tye
* 1 - byte Flags
* 8 - bytes CIST Root Identifier
* 4 - bytes CIST External Path Cost
* 8 - bytes CIST Regional Root Identifier
* 2 - bytes CIST Port Identifier
* 2 - bytes Message Age
* 2 - bytes Max age
* 2 - bytes Hello Time
* 2 - bytes Forward delay
* 1 - byte Version 1 length. Must be 0
* 2 - bytes Version 3 length
* 1 - byte Config Identifier
* 32 - bytes Config Name
* 2 - bytes Revision level
* 16 - bytes Config Digest [MD5]
* 4 - bytes CIST Internal Root Path Cost
* 8 - bytes CIST Bridge Identifier
* 1 - byte CIST Remaining Hops
* 16 - bytes MSTI information [Max 64 MSTI, each 16 bytes]
*
*
* SPB BPDU
* Ref. IEEE 802.1aq. Section 14
*
* 2 - bytes Version 4 length
* 1 - byte Aux Config Identifier
* 32 - bytes Aux Config Name
* 2 - bytes Aux Revision level
* 16 - bytes Aux Config Digest [MD5]
* 1 - byte (1 - 2) Agreement Number
* (3 - 4) Discarded Agreement Number
* (5) Agreement Valid Flag
* (6) Restricted Role Flag
* (7 - 8) Unused sent zero
* 1 - byte Unused
* 1 - byte (1 - 4) Agreement Digest Format Identifier
* (5 - 8) Agreement Digest Format Capabilities
* 1 - byte (1 - 4) Agreement Digest Convention Identifier
* (5 - 8) Agreement Digest Convention Capabilities
* 2 - bytes Agreement Digest Edge Count
* 8 - byte Reserved Set
* 20 - bytes Computed Topology Digest
*
*
* MSTI Payload
*
* 1 - byte MSTI flag
* 8 - bytes MSTI Regional Root Identifier
* 4 - bytes MSTI Regional Path Cost
* 1 - byte MSTI Bridge Priority
* 1 - byte MSTI Port Priority
* 1 - byte MSTI Remaining Hops
*
*/
#define MST_BPDU_MSTI_LENGTH 16
#define MST_BPDU_CONFIG_INFO_LENGTH 64
/* Offsets of fields from the begginning for the packet */
#define MST_BPDU_VER3_LEN_OFFSET 36
#define MST_BPDU_CONFIG_NAME_OFFSET 39
#define MST_BPDU_CONFIG_DIGEST_OFFSET 73
#define MST_BPDU_CIST_INT_PATH_COST_OFFSET 89
#define MST_BPDU_CIST_BRIDGE_ID_OFFSET 93
#define MST_BPDU_CIST_REMAIN_HOPS_OFFSET 101
#define MST_BPDU_MSTI_OFFSET 102
/* Offsets within an MSTI */
#define MST_BPDU_MSTI_ROOT_PRIO_OFFSET 1
#define MST_BPDU_MSTI_ROOT_PATH_COST_OFFSET 9
#define MST_BPDU_MSTI_BRIDGE_PRIO_OFFSET 13
#define MST_BPDU_MSTI_PORT_PRIO_OFFSET 14
#define MST_BPDU_MSTI_REMAIN_HOPS_OFFSET 15
#define SPB_BPDU_MIN_LEN 87
#define SPB_BPDU_CONFIG_NAME_OFFSET 3
#define SPB_BPDU_CONFIG_REV_OFFSET SPB_BPDU_CONFIG_NAME_OFFSET + 32
#define SPB_BPDU_CONFIG_DIGEST_OFFSET SPB_BPDU_CONFIG_REV_OFFSET + 2
#define SPB_BPDU_AGREEMENT_OFFSET SPB_BPDU_CONFIG_DIGEST_OFFSET + 16
#define SPB_BPDU_AGREEMENT_UNUSED_OFFSET SPB_BPDU_AGREEMENT_OFFSET + 1
#define SPB_BPDU_AGREEMENT_FORMAT_OFFSET SPB_BPDU_AGREEMENT_UNUSED_OFFSET + 1
#define SPB_BPDU_AGREEMENT_CON_OFFSET SPB_BPDU_AGREEMENT_FORMAT_OFFSET + 1
#define SPB_BPDU_AGREEMENT_EDGE_OFFSET SPB_BPDU_AGREEMENT_CON_OFFSET + 1
#define SPB_BPDU_AGREEMENT_RES1_OFFSET SPB_BPDU_AGREEMENT_EDGE_OFFSET + 2
#define SPB_BPDU_AGREEMENT_RES2_OFFSET SPB_BPDU_AGREEMENT_RES1_OFFSET + 4
#define SPB_BPDU_AGREEMENT_DIGEST_OFFSET SPB_BPDU_AGREEMENT_RES2_OFFSET + 4
static int
stp_print_mstp_bpdu(netdissect_options *ndo, const struct stp_bpdu_ *stp_bpdu,
u_int length)
{
const u_char *ptr;
uint16_t v3len;
uint16_t len;
uint16_t msti;
u_int offset;
ptr = (const u_char *)stp_bpdu;
ND_PRINT((ndo, ", CIST Flags [%s], length %u",
bittok2str(stp_bpdu_flag_values, "none", stp_bpdu->flags), length));
/*
* in non-verbose mode just print the flags.
*/
if (!ndo->ndo_vflag) {
return 1;
}
ND_TCHECK(stp_bpdu->flags);
ND_PRINT((ndo, "\n\tport-role %s, ",
tok2str(rstp_obj_port_role_values, "Unknown",
RSTP_EXTRACT_PORT_ROLE(stp_bpdu->flags))));
ND_TCHECK(stp_bpdu->root_path_cost);
ND_PRINT((ndo, "CIST root-id %s, CIST ext-pathcost %u",
stp_print_bridge_id((const u_char *)&stp_bpdu->root_id),
EXTRACT_32BITS(&stp_bpdu->root_path_cost)));
ND_TCHECK(stp_bpdu->bridge_id);
ND_PRINT((ndo, "\n\tCIST regional-root-id %s, ",
stp_print_bridge_id((const u_char *)&stp_bpdu->bridge_id)));
ND_TCHECK(stp_bpdu->port_id);
ND_PRINT((ndo, "CIST port-id %04x,", EXTRACT_16BITS(&stp_bpdu->port_id)));
ND_TCHECK(stp_bpdu->forward_delay);
ND_PRINT((ndo, "\n\tmessage-age %.2fs, max-age %.2fs"
", hello-time %.2fs, forwarding-delay %.2fs",
(float)EXTRACT_16BITS(&stp_bpdu->message_age) / STP_TIME_BASE,
(float)EXTRACT_16BITS(&stp_bpdu->max_age) / STP_TIME_BASE,
(float)EXTRACT_16BITS(&stp_bpdu->hello_time) / STP_TIME_BASE,
(float)EXTRACT_16BITS(&stp_bpdu->forward_delay) / STP_TIME_BASE));
ND_TCHECK_16BITS(ptr + MST_BPDU_VER3_LEN_OFFSET);
ND_PRINT((ndo, "\n\tv3len %d, ", EXTRACT_16BITS(ptr + MST_BPDU_VER3_LEN_OFFSET)));
ND_TCHECK_32BITS(ptr + MST_BPDU_CONFIG_DIGEST_OFFSET + 12);
ND_PRINT((ndo, "MCID Name "));
if (fn_printzp(ndo, ptr + MST_BPDU_CONFIG_NAME_OFFSET, 32, ndo->ndo_snapend))
goto trunc;
ND_PRINT((ndo, ", rev %u,"
"\n\t\tdigest %08x%08x%08x%08x, ",
EXTRACT_16BITS(ptr + MST_BPDU_CONFIG_NAME_OFFSET + 32),
EXTRACT_32BITS(ptr + MST_BPDU_CONFIG_DIGEST_OFFSET),
EXTRACT_32BITS(ptr + MST_BPDU_CONFIG_DIGEST_OFFSET + 4),
EXTRACT_32BITS(ptr + MST_BPDU_CONFIG_DIGEST_OFFSET + 8),
EXTRACT_32BITS(ptr + MST_BPDU_CONFIG_DIGEST_OFFSET + 12)));
ND_TCHECK_32BITS(ptr + MST_BPDU_CIST_INT_PATH_COST_OFFSET);
ND_PRINT((ndo, "CIST int-root-pathcost %u,",
EXTRACT_32BITS(ptr + MST_BPDU_CIST_INT_PATH_COST_OFFSET)));
ND_TCHECK_BRIDGE_ID(ptr + MST_BPDU_CIST_BRIDGE_ID_OFFSET);
ND_PRINT((ndo, "\n\tCIST bridge-id %s, ",
stp_print_bridge_id(ptr + MST_BPDU_CIST_BRIDGE_ID_OFFSET)));
ND_TCHECK(ptr[MST_BPDU_CIST_REMAIN_HOPS_OFFSET]);
ND_PRINT((ndo, "CIST remaining-hops %d", ptr[MST_BPDU_CIST_REMAIN_HOPS_OFFSET]));
/* Dump all MSTI's */
ND_TCHECK_16BITS(ptr + MST_BPDU_VER3_LEN_OFFSET);
v3len = EXTRACT_16BITS(ptr + MST_BPDU_VER3_LEN_OFFSET);
if (v3len > MST_BPDU_CONFIG_INFO_LENGTH) {
len = v3len - MST_BPDU_CONFIG_INFO_LENGTH;
offset = MST_BPDU_MSTI_OFFSET;
while (len >= MST_BPDU_MSTI_LENGTH) {
ND_TCHECK2(*(ptr + offset), MST_BPDU_MSTI_LENGTH);
msti = EXTRACT_16BITS(ptr + offset +
MST_BPDU_MSTI_ROOT_PRIO_OFFSET);
msti = msti & 0x0FFF;
ND_PRINT((ndo, "\n\tMSTI %d, Flags [%s], port-role %s",
msti, bittok2str(stp_bpdu_flag_values, "none", ptr[offset]),
tok2str(rstp_obj_port_role_values, "Unknown",
RSTP_EXTRACT_PORT_ROLE(ptr[offset]))));
ND_PRINT((ndo, "\n\t\tMSTI regional-root-id %s, pathcost %u",
stp_print_bridge_id(ptr + offset +
MST_BPDU_MSTI_ROOT_PRIO_OFFSET),
EXTRACT_32BITS(ptr + offset +
MST_BPDU_MSTI_ROOT_PATH_COST_OFFSET)));
ND_PRINT((ndo, "\n\t\tMSTI bridge-prio %d, port-prio %d, hops %d",
ptr[offset + MST_BPDU_MSTI_BRIDGE_PRIO_OFFSET] >> 4,
ptr[offset + MST_BPDU_MSTI_PORT_PRIO_OFFSET] >> 4,
ptr[offset + MST_BPDU_MSTI_REMAIN_HOPS_OFFSET]));
len -= MST_BPDU_MSTI_LENGTH;
offset += MST_BPDU_MSTI_LENGTH;
}
}
return 1;
trunc:
return 0;
}
static int
stp_print_spb_bpdu(netdissect_options *ndo, const struct stp_bpdu_ *stp_bpdu,
u_int offset)
{
const u_char *ptr;
/*
* in non-verbose mode don't print anything.
*/
if (!ndo->ndo_vflag) {
return 1;
}
ptr = (const u_char *)stp_bpdu;
ND_TCHECK_32BITS(ptr + offset + SPB_BPDU_AGREEMENT_DIGEST_OFFSET + 16);
ND_PRINT((ndo, "\n\tv4len %d, ", EXTRACT_16BITS (ptr + offset)));
ND_PRINT((ndo, "AUXMCID Name "));
if (fn_printzp(ndo, ptr + offset + SPB_BPDU_CONFIG_NAME_OFFSET, 32,
ndo->ndo_snapend))
goto trunc;
ND_PRINT((ndo, ", Rev %u,\n\t\tdigest %08x%08x%08x%08x",
EXTRACT_16BITS(ptr + offset + SPB_BPDU_CONFIG_REV_OFFSET),
EXTRACT_32BITS(ptr + offset + SPB_BPDU_CONFIG_DIGEST_OFFSET),
EXTRACT_32BITS(ptr + offset + SPB_BPDU_CONFIG_DIGEST_OFFSET + 4),
EXTRACT_32BITS(ptr + offset + SPB_BPDU_CONFIG_DIGEST_OFFSET + 8),
EXTRACT_32BITS(ptr + offset + SPB_BPDU_CONFIG_DIGEST_OFFSET + 12)));
ND_PRINT((ndo, "\n\tAgreement num %d, Discarded Agreement num %d, Agreement valid-"
"flag %d,\n\tRestricted role-flag: %d, Format id %d cap %d, "
"Convention id %d cap %d,\n\tEdge count %d, "
"Agreement digest %08x%08x%08x%08x%08x\n",
ptr[offset + SPB_BPDU_AGREEMENT_OFFSET]>>6,
ptr[offset + SPB_BPDU_AGREEMENT_OFFSET]>>4 & 0x3,
ptr[offset + SPB_BPDU_AGREEMENT_OFFSET]>>3 & 0x1,
ptr[offset + SPB_BPDU_AGREEMENT_OFFSET]>>2 & 0x1,
ptr[offset + SPB_BPDU_AGREEMENT_FORMAT_OFFSET]>>4,
ptr[offset + SPB_BPDU_AGREEMENT_FORMAT_OFFSET]&0x00ff,
ptr[offset + SPB_BPDU_AGREEMENT_CON_OFFSET]>>4,
ptr[offset + SPB_BPDU_AGREEMENT_CON_OFFSET]&0x00ff,
EXTRACT_16BITS(ptr + offset + SPB_BPDU_AGREEMENT_EDGE_OFFSET),
EXTRACT_32BITS(ptr + offset + SPB_BPDU_AGREEMENT_DIGEST_OFFSET),
EXTRACT_32BITS(ptr + offset + SPB_BPDU_AGREEMENT_DIGEST_OFFSET+4),
EXTRACT_32BITS(ptr + offset + SPB_BPDU_AGREEMENT_DIGEST_OFFSET+8),
EXTRACT_32BITS(ptr + offset + SPB_BPDU_AGREEMENT_DIGEST_OFFSET+12),
EXTRACT_32BITS(ptr + offset + SPB_BPDU_AGREEMENT_DIGEST_OFFSET+16)));
return 1;
trunc:
return 0;
}
/*
* Print 802.1d / 802.1w / 802.1q (mstp) / 802.1aq (spb) packets.
*/
void
stp_print(netdissect_options *ndo, const u_char *p, u_int length)
{
const struct stp_bpdu_ *stp_bpdu;
u_int mstp_len;
u_int spb_len;
stp_bpdu = (const struct stp_bpdu_*)p;
/* Minimum STP Frame size. */
if (length < 4)
goto trunc;
ND_TCHECK(stp_bpdu->protocol_id);
if (EXTRACT_16BITS(&stp_bpdu->protocol_id)) {
ND_PRINT((ndo, "unknown STP version, length %u", length));
return;
}
ND_TCHECK(stp_bpdu->protocol_version);
ND_PRINT((ndo, "STP %s", tok2str(stp_proto_values, "Unknown STP protocol (0x%02x)",
stp_bpdu->protocol_version)));
switch (stp_bpdu->protocol_version) {
case STP_PROTO_REGULAR:
case STP_PROTO_RAPID:
case STP_PROTO_MSTP:
case STP_PROTO_SPB:
break;
default:
return;
}
ND_TCHECK(stp_bpdu->bpdu_type);
ND_PRINT((ndo, ", %s", tok2str(stp_bpdu_type_values, "Unknown BPDU Type (0x%02x)",
stp_bpdu->bpdu_type)));
switch (stp_bpdu->bpdu_type) {
case STP_BPDU_TYPE_CONFIG:
if (length < sizeof(struct stp_bpdu_) - 1) {
goto trunc;
}
if (!stp_print_config_bpdu(ndo, stp_bpdu, length))
goto trunc;
break;
case STP_BPDU_TYPE_RSTP:
if (stp_bpdu->protocol_version == STP_PROTO_RAPID) {
if (length < sizeof(struct stp_bpdu_)) {
goto trunc;
}
if (!stp_print_config_bpdu(ndo, stp_bpdu, length))
goto trunc;
} else if (stp_bpdu->protocol_version == STP_PROTO_MSTP ||
stp_bpdu->protocol_version == STP_PROTO_SPB) {
if (length < STP_BPDU_MSTP_MIN_LEN) {
goto trunc;
}
ND_TCHECK(stp_bpdu->v1_length);
if (stp_bpdu->v1_length != 0) {
/* FIX ME: Emit a message here ? */
goto trunc;
}
/* Validate v3 length */
ND_TCHECK_16BITS(p + MST_BPDU_VER3_LEN_OFFSET);
mstp_len = EXTRACT_16BITS(p + MST_BPDU_VER3_LEN_OFFSET);
mstp_len += 2; /* length encoding itself is 2 bytes */
if (length < (sizeof(struct stp_bpdu_) + mstp_len)) {
goto trunc;
}
if (!stp_print_mstp_bpdu(ndo, stp_bpdu, length))
goto trunc;
if (stp_bpdu->protocol_version == STP_PROTO_SPB)
{
/* Validate v4 length */
ND_TCHECK_16BITS(p + MST_BPDU_VER3_LEN_OFFSET + mstp_len);
spb_len = EXTRACT_16BITS (p + MST_BPDU_VER3_LEN_OFFSET + mstp_len);
spb_len += 2;
if (length < (sizeof(struct stp_bpdu_) + mstp_len + spb_len) ||
spb_len < SPB_BPDU_MIN_LEN) {
goto trunc;
}
if (!stp_print_spb_bpdu(ndo, stp_bpdu, (sizeof(struct stp_bpdu_) + mstp_len)))
goto trunc;
}
}
break;
case STP_BPDU_TYPE_TOPO_CHANGE:
/* always empty message - just break out */
break;
default:
break;
}
return;
trunc:
ND_PRINT((ndo, "[|stp %d]", length));
}
/*
* Local Variables:
* c-style: whitesmith
* c-basic-offset: 4
* End:
*/
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