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Commit 405c0059 authored by Neal Cardwell's avatar Neal Cardwell Committed by David S. Miller
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inet_diag: validate byte code to prevent oops in inet_diag_bc_run() 



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: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1c95df85

net/ipv4/inet_diag.c

+45 −3
Original line number Original line Diff line number Diff line
@@ -513,6 +513,44 @@ static int valid_cc(const void *bc, int len, int cc) 
	return 0;

	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)

static int inet_diag_bc_audit(const void *bytecode, int bytecode_len)

{

{

	const void *bc = bytecode;

	const void *bc = bytecode;
@@ -520,18 +558,22 @@ static int inet_diag_bc_audit(const void *bytecode, int bytecode_len) 




	while (len > 0) {

	while (len > 0) {

		const struct inet_diag_bc_op *op = bc;

		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);

//printk("BC: %d %d %d {%d} / %d\n", op->code, op->yes, op->no, op[1].no, len);

		switch (op->code) {

		switch (op->code) {

		case INET_DIAG_BC_AUTO:

		case INET_DIAG_BC_S_COND:

		case INET_DIAG_BC_S_COND:

		case INET_DIAG_BC_D_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_GE:

		case INET_DIAG_BC_S_LE:

		case INET_DIAG_BC_S_LE:

		case INET_DIAG_BC_D_GE:

		case INET_DIAG_BC_D_GE:

		case INET_DIAG_BC_D_LE:

		case INET_DIAG_BC_D_LE:

		case INET_DIAG_BC_JMP:

		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;

				return -EINVAL;

			if (op->no < len &&

			if (op->no < len &&

			    !valid_cc(bytecode, bytecode_len, len - op->no))

			    !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:

		default:

			return -EINVAL;

			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;

			return -EINVAL;

		bc  += op->yes;

		bc  += op->yes;

		len -= op->yes;

		len -= op->yes;