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cipso: handle CIPSO options correctly when NetLabel is disabled

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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>
This commit is contained in:
Paul Moore 2012-06-01 05:54:56 +00:00 committed by David S. Miller
parent cc9b17ad29
commit 20e2a86485
1 changed files with 28 additions and 1 deletions
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29
include/net/cipso_ipv4.h
View File

@ -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 */