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rose: Add length checks to CALL_REQUEST parsing
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Define some constant offsets for CALL_REQUEST based on the description
at <http://www.techfest.com/networking/wan/x25plp.htm> and the
definition of ROSE as using 10-digit (5-byte) addresses.  Use them
consistently.  Validate all implicit and explicit facilities lengths.
Validate the address length byte rather than either trusting or
assuming its value.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Ben Hutchings authored and David S. Miller committed Mar 28, 2011
1 parent be20250 commit e0bccd3
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Showing 5 changed files with 93 additions and 47 deletions.
8 changes: 7 additions & 1 deletion include/net/rose.h
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,12 @@

#define ROSE_MIN_LEN 3

#define ROSE_CALL_REQ_ADDR_LEN_OFF 3
#define ROSE_CALL_REQ_ADDR_LEN_VAL 0xAA /* each address is 10 digits */
#define ROSE_CALL_REQ_DEST_ADDR_OFF 4
#define ROSE_CALL_REQ_SRC_ADDR_OFF 9
#define ROSE_CALL_REQ_FACILITIES_OFF 14

#define ROSE_GFI 0x10
#define ROSE_Q_BIT 0x80
#define ROSE_D_BIT 0x40
Expand Down Expand Up @@ -214,7 +220,7 @@ extern void rose_requeue_frames(struct sock *);
extern int rose_validate_nr(struct sock *, unsigned short);
extern void rose_write_internal(struct sock *, int);
extern int rose_decode(struct sk_buff *, int *, int *, int *, int *, int *);
extern int rose_parse_facilities(unsigned char *, struct rose_facilities_struct *);
extern int rose_parse_facilities(unsigned char *, unsigned int, struct rose_facilities_struct *);
extern void rose_disconnect(struct sock *, int, int, int);

/* rose_timer.c */
Expand Down
8 changes: 4 additions & 4 deletions net/rose/af_rose.c
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Original file line number Diff line number Diff line change
Expand Up @@ -978,7 +978,7 @@ int rose_rx_call_request(struct sk_buff *skb, struct net_device *dev, struct ros
struct sock *make;
struct rose_sock *make_rose;
struct rose_facilities_struct facilities;
int n, len;
int n;

skb->sk = NULL; /* Initially we don't know who it's for */

Expand All @@ -987,9 +987,9 @@ int rose_rx_call_request(struct sk_buff *skb, struct net_device *dev, struct ros
*/
memset(&facilities, 0x00, sizeof(struct rose_facilities_struct));

len = (((skb->data[3] >> 4) & 0x0F) + 1) >> 1;
len += (((skb->data[3] >> 0) & 0x0F) + 1) >> 1;
if (!rose_parse_facilities(skb->data + len + 4, &facilities)) {
if (!rose_parse_facilities(skb->data + ROSE_CALL_REQ_FACILITIES_OFF,
skb->len - ROSE_CALL_REQ_FACILITIES_OFF,
&facilities)) {
rose_transmit_clear_request(neigh, lci, ROSE_INVALID_FACILITY, 76);
return 0;
}
Expand Down
13 changes: 12 additions & 1 deletion net/rose/rose_loopback.c
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Original file line number Diff line number Diff line change
Expand Up @@ -73,9 +73,20 @@ static void rose_loopback_timer(unsigned long param)
unsigned int lci_i, lci_o;

while ((skb = skb_dequeue(&loopback_queue)) != NULL) {
if (skb->len < ROSE_MIN_LEN) {
kfree_skb(skb);
continue;
}
lci_i = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
frametype = skb->data[2];
dest = (rose_address *)(skb->data + 4);
if (frametype == ROSE_CALL_REQUEST &&
(skb->len <= ROSE_CALL_REQ_FACILITIES_OFF ||
skb->data[ROSE_CALL_REQ_ADDR_LEN_OFF] !=
ROSE_CALL_REQ_ADDR_LEN_VAL)) {
kfree_skb(skb);
continue;
}
dest = (rose_address *)(skb->data + ROSE_CALL_REQ_DEST_ADDR_OFF);
lci_o = ROSE_DEFAULT_MAXVC + 1 - lci_i;

skb_reset_transport_header(skb);
Expand Down
20 changes: 13 additions & 7 deletions net/rose/rose_route.c
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Original file line number Diff line number Diff line change
Expand Up @@ -861,18 +861,25 @@ int rose_route_frame(struct sk_buff *skb, ax25_cb *ax25)
unsigned int lci, new_lci;
unsigned char cause, diagnostic;
struct net_device *dev;
int len, res = 0;
int res = 0;
char buf[11];

#if 0
if (call_in_firewall(PF_ROSE, skb->dev, skb->data, NULL, &skb) != FW_ACCEPT)
return res;
#endif

if (skb->len < ROSE_MIN_LEN)
return res;
frametype = skb->data[2];
lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
src_addr = (rose_address *)(skb->data + 9);
dest_addr = (rose_address *)(skb->data + 4);
if (frametype == ROSE_CALL_REQUEST &&
(skb->len <= ROSE_CALL_REQ_FACILITIES_OFF ||
skb->data[ROSE_CALL_REQ_ADDR_LEN_OFF] !=
ROSE_CALL_REQ_ADDR_LEN_VAL))
return res;
src_addr = (rose_address *)(skb->data + ROSE_CALL_REQ_SRC_ADDR_OFF);
dest_addr = (rose_address *)(skb->data + ROSE_CALL_REQ_DEST_ADDR_OFF);

spin_lock_bh(&rose_neigh_list_lock);
spin_lock_bh(&rose_route_list_lock);
Expand Down Expand Up @@ -1010,12 +1017,11 @@ int rose_route_frame(struct sk_buff *skb, ax25_cb *ax25)
goto out;
}

len = (((skb->data[3] >> 4) & 0x0F) + 1) >> 1;
len += (((skb->data[3] >> 0) & 0x0F) + 1) >> 1;

memset(&facilities, 0x00, sizeof(struct rose_facilities_struct));

if (!rose_parse_facilities(skb->data + len + 4, &facilities)) {
if (!rose_parse_facilities(skb->data + ROSE_CALL_REQ_FACILITIES_OFF,
skb->len - ROSE_CALL_REQ_FACILITIES_OFF,
&facilities)) {
rose_transmit_clear_request(rose_neigh, lci, ROSE_INVALID_FACILITY, 76);
goto out;
}
Expand Down
91 changes: 57 additions & 34 deletions net/rose/rose_subr.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -142,7 +142,7 @@ void rose_write_internal(struct sock *sk, int frametype)
*dptr++ = ROSE_GFI | lci1;
*dptr++ = lci2;
*dptr++ = frametype;
*dptr++ = 0xAA;
*dptr++ = ROSE_CALL_REQ_ADDR_LEN_VAL;
memcpy(dptr, &rose->dest_addr, ROSE_ADDR_LEN);
dptr += ROSE_ADDR_LEN;
memcpy(dptr, &rose->source_addr, ROSE_ADDR_LEN);
Expand Down Expand Up @@ -246,12 +246,16 @@ static int rose_parse_national(unsigned char *p, struct rose_facilities_struct *
do {
switch (*p & 0xC0) {
case 0x00:
if (len < 2)
return -1;
p += 2;
n += 2;
len -= 2;
break;

case 0x40:
if (len < 3)
return -1;
if (*p == FAC_NATIONAL_RAND)
facilities->rand = ((p[1] << 8) & 0xFF00) + ((p[2] << 0) & 0x00FF);
p += 3;
Expand All @@ -260,32 +264,48 @@ static int rose_parse_national(unsigned char *p, struct rose_facilities_struct *
break;

case 0x80:
if (len < 4)
return -1;
p += 4;
n += 4;
len -= 4;
break;

case 0xC0:
if (len < 2)
return -1;
l = p[1];
if (len < 2 + l)
return -1;
if (*p == FAC_NATIONAL_DEST_DIGI) {
if (!fac_national_digis_received) {
if (l < AX25_ADDR_LEN)
return -1;
memcpy(&facilities->source_digis[0], p + 2, AX25_ADDR_LEN);
facilities->source_ndigis = 1;
}
}
else if (*p == FAC_NATIONAL_SRC_DIGI) {
if (!fac_national_digis_received) {
if (l < AX25_ADDR_LEN)
return -1;
memcpy(&facilities->dest_digis[0], p + 2, AX25_ADDR_LEN);
facilities->dest_ndigis = 1;
}
}
else if (*p == FAC_NATIONAL_FAIL_CALL) {
if (l < AX25_ADDR_LEN)
return -1;
memcpy(&facilities->fail_call, p + 2, AX25_ADDR_LEN);
}
else if (*p == FAC_NATIONAL_FAIL_ADD) {
if (l < 1 + ROSE_ADDR_LEN)
return -1;
memcpy(&facilities->fail_addr, p + 3, ROSE_ADDR_LEN);
}
else if (*p == FAC_NATIONAL_DIGIS) {
if (l % AX25_ADDR_LEN)
return -1;
fac_national_digis_received = 1;
facilities->source_ndigis = 0;
facilities->dest_ndigis = 0;
Expand Down Expand Up @@ -319,24 +339,32 @@ static int rose_parse_ccitt(unsigned char *p, struct rose_facilities_struct *fac
do {
switch (*p & 0xC0) {
case 0x00:
if (len < 2)
return -1;
p += 2;
n += 2;
len -= 2;
break;

case 0x40:
if (len < 3)
return -1;
p += 3;
n += 3;
len -= 3;
break;

case 0x80:
if (len < 4)
return -1;
p += 4;
n += 4;
len -= 4;
break;

case 0xC0:
if (len < 2)
return -1;
l = p[1];

/* Prevent overflows*/
Expand Down Expand Up @@ -365,49 +393,44 @@ static int rose_parse_ccitt(unsigned char *p, struct rose_facilities_struct *fac
return n;
}

int rose_parse_facilities(unsigned char *p,
int rose_parse_facilities(unsigned char *p, unsigned packet_len,
struct rose_facilities_struct *facilities)
{
int facilities_len, len;

facilities_len = *p++;

if (facilities_len == 0)
if (facilities_len == 0 || (unsigned)facilities_len > packet_len)
return 0;

while (facilities_len > 0) {
if (*p == 0x00) {
facilities_len--;
p++;

switch (*p) {
case FAC_NATIONAL: /* National */
len = rose_parse_national(p + 1, facilities, facilities_len - 1);
if (len < 0)
return 0;
facilities_len -= len + 1;
p += len + 1;
break;

case FAC_CCITT: /* CCITT */
len = rose_parse_ccitt(p + 1, facilities, facilities_len - 1);
if (len < 0)
return 0;
facilities_len -= len + 1;
p += len + 1;
break;

default:
printk(KERN_DEBUG "ROSE: rose_parse_facilities - unknown facilities family %02X\n", *p);
facilities_len--;
p++;
break;
}
} else
break; /* Error in facilities format */
while (facilities_len >= 3 && *p == 0x00) {
facilities_len--;
p++;

switch (*p) {
case FAC_NATIONAL: /* National */
len = rose_parse_national(p + 1, facilities, facilities_len - 1);
break;

case FAC_CCITT: /* CCITT */
len = rose_parse_ccitt(p + 1, facilities, facilities_len - 1);
break;

default:
printk(KERN_DEBUG "ROSE: rose_parse_facilities - unknown facilities family %02X\n", *p);
len = 1;
break;
}

if (len < 0)
return 0;
if (WARN_ON(len >= facilities_len))
return 0;
facilities_len -= len + 1;
p += len + 1;
}

return 1;
return facilities_len == 0;
}

static int rose_create_facilities(unsigned char *buffer, struct rose_sock *rose)
Expand Down

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