[ 020/187] cipso: handle CIPSO options correctly when NetLabel is disabled

Greg Kroah-Hartman
2012-07-12T22:36:47Z

From: Paul Moore <pmoore@redhat.com>

[ Upstream commit 20e2a86485967c385d7c7befc1646e4d1d39362e ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/net/cipso_ipv4.h | 29 ++++++++++++++++++++++++++++-
1 file changed, 28 insertions(+), 1 deletion(-)

--- a/include/net/cipso_ipv4.h
+++ b/include/net/cipso_ipv4.h
@@ -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_getatt
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 */