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inet_diag: validate byte code to prevent oops in inet_diag_bc_run()

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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>
This commit is contained in:
Neal Cardwell 2012-12-08 19:43:22 +00:00 committed by David S. Miller
parent 1c95df85ca
commit 405c005949
1 changed files with 45 additions and 3 deletions
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48
net/ipv4/inet_diag.c
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@ -513,6 +513,44 @@ static int valid_cc(const void *bc, int len, int cc)
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;
@ -520,18 +558,22 @@ static int inet_diag_bc_audit(const void *bytecode, int bytecode_len)
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))
@ -542,7 +584,7 @@ static int inet_diag_bc_audit(const void *bytecode, int bytecode_len)
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;