[ 10/80] inet_diag: validate byte code to prevent oops in inet_diag_bc_run()

Greg Kroah-Hartman
2013-01-09T21:45:20Z

From: Neal Cardwell <ncardwell@google.com>

[ Upstream commit 405c005949e47b6e91359159c24753519ded0c67 ]

Add logic to validate INET_DIAG_BC_S_COND and INET_DIAG_BC_D_COND
operations.

Previously we did not validate the inet_diag_hostcond, address family,
address length, and prefix length. So a malicious user could make the
kernel read beyond the end of the bytecode array by claiming to have a
whole inet_diag_hostcond when the bytecode was not long enough to
contain a whole inet_diag_hostcond of the given address family. Or
they could make the kernel read up to about 27 bytes beyond the end of
a connection address by passing a prefix length that exceeded the
length of addresses of the given family.

Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/inet_diag.c | 48 +++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 45 insertions(+), 3 deletions(-)

--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -504,6 +504,44 @@ static int valid_cc(const void *bc, int
return 0;
}

+/* Validate an inet_diag_hostcond. */
+static bool valid_hostcond(const struct inet_diag_bc_op *op, int len,
+ int *min_len)
+{
+ int addr_len;
+ struct inet_diag_hostcond *cond;
+
+ /* Check hostcond space. */
+ *min_len += sizeof(struct inet_diag_hostcond);
+ if (len < *min_len)
+ return false;
+ cond = (struct inet_diag_hostcond *)(op + 1);
+
+ /* Check address family and address length. */
+ switch (cond->family) {
+ case AF_UNSPEC:
+ addr_len = 0;
+ break;
+ case AF_INET:
+ addr_len = sizeof(struct in_addr);
+ break;
+ case AF_INET6:
+ addr_len = sizeof(struct in6_addr);
+ break;
+ default:
+ return false;
+ }
+ *min_len += addr_len;
+ if (len < *min_len)
+ return false;
+
+ /* Check prefix length (in bits) vs address length (in bytes). */
+ if (cond->prefix_len > 8 * addr_len)
+ return false;
+
+ return true;
+}
+
static int inet_diag_bc_audit(const void *bytecode, int bytecode_len)
{
const void *bc = bytecode;
@@ -511,18 +549,22 @@ static int inet_diag_bc_audit(const void

while (len > 0) {
const struct inet_diag_bc_op *op = bc;
+ int min_len = sizeof(struct inet_diag_bc_op);

//printk("BC: %d %d %d {%d} / %d\n", op->code, op->yes, op->no, op[1].no, len);
switch (op->code) {
- case INET_DIAG_BC_AUTO:
case INET_DIAG_BC_S_COND:
case INET_DIAG_BC_D_COND:
+ if (!valid_hostcond(bc, len, &min_len))
+ return -EINVAL;
+ /* fall through */
+ case INET_DIAG_BC_AUTO:
case INET_DIAG_BC_S_GE:
case INET_DIAG_BC_S_LE:
case INET_DIAG_BC_D_GE:
case INET_DIAG_BC_D_LE:
case INET_DIAG_BC_JMP:
- if (op->no < 4 || op->no > len + 4 || op->no & 3)
+ if (op->no < min_len || op->no > len + 4 || op->no & 3)
return -EINVAL;
if (op->no < len &&
!valid_cc(bytecode, bytecode_len, len - op->no))
@@ -533,7 +575,7 @@ static int inet_diag_bc_audit(const void
default:
return -EINVAL;
}
- if (op->yes < 4 || op->yes > len + 4 || op->yes & 3)
+ if (op->yes < min_len || op->yes > len + 4 || op->yes & 3)
return -EINVAL;
bc += op->yes;
len -= op->yes;