rose: Add length checks to CALL_REQUEST parsing
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>
diff --git a/net/rose/rose_subr.c b/net/rose/rose_subr.c
index 174d51c..f6c71ca 100644
--- a/net/rose/rose_subr.c
+++ b/net/rose/rose_subr.c
@@ -142,7 +142,7 @@
*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);
@@ -246,12 +246,16 @@
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;
@@ -260,32 +264,48 @@
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;
@@ -319,24 +339,32 @@
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*/
@@ -365,49 +393,44 @@
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++;
+ 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);
- if (len < 0)
- return 0;
- facilities_len -= len + 1;
- p += len + 1;
- break;
+ 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);
- 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);
+ 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 */
+ 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)