Commit 20e2a864 authored Jun 01, 2012 by Paul Moore Committed by David S. Miller Jun 01, 2012

cipso: handle CIPSO options correctly when NetLabel is disabled



When NetLabel is not enabled, e.g. CONFIG_NETLABEL=n, and the system
receives a CIPSO tagged packet it is dropped (cipso_v4_validate()
returns non-zero).  In most cases this is the correct and desired
behavior, however, in the case where we are simply forwarding the
traffic, e.g. acting as a network bridge, this becomes a problem.

This patch fixes the forwarding problem by providing the basic CIPSO
validation code directly in ip_options_compile() without the need for
the NetLabel or CIPSO code.  The new validation code can not perform
any of the CIPSO option label/value verification that
cipso_v4_validate() does, but it can verify the basic CIPSO option
format.

The behavior when NetLabel is enabled is unchanged.

Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent cc9b17ad

include/net/cipso_ipv4.h

+28 −1

Original line number	Diff line number	Diff line
		@@ -42,6 +42,7 @@
		#include <net/netlabel.h>
		#include <net/request_sock.h>
		#include <linux/atomic.h>
		#include <asm/unaligned.h>

		/* known doi values */
		#define CIPSO_V4_DOI_UNKNOWN 0x00000000
		@@ -285,7 +286,33 @@ static inline int cipso_v4_skbuff_getattr(const struct sk_buff *skb,
		static inline int cipso_v4_validate(const struct sk_buff *skb,
		unsigned char **option)
		{
		return -ENOSYS;
		unsigned char opt = option;
		unsigned char err_offset = 0;
		u8 opt_len = opt[1];
		u8 opt_iter;

		if (opt_len < 8) {
		err_offset = 1;
		goto out;
		}

		if (get_unaligned_be32(&opt[2]) == 0) {
		err_offset = 2;
		goto out;
		}

		for (opt_iter = 6; opt_iter < opt_len;) {
		if (opt[opt_iter + 1] > (opt_len - opt_iter)) {
		err_offset = opt_iter + 1;
		goto out;
		}
		opt_iter += opt[opt_iter + 1];
		}

		out:
		*option = opt + err_offset;
		return err_offset;

		}
		#endif /* CONFIG_NETLABEL */