[PATCH RFC] Smack: Fix handling of IPv4 traffic received by PF_INET6 sockets

[Piotr Sawicki]

On 07/17/2018 01:33 AM, Casey Schaufler wrote:
> On 7/10/2018 12:05 AM, Piotr Sawicki wrote:
>> A socket which has sk_family set to PF_INET6 is able to receive not
>> only IPv6 but also IPv4 traffic (IPv4-mapped IPv6 addresses).
>>
>> Prior to this patch, the smk_skb_to_addr_ipv6() could have been
>> called for socket buffers containing IPv4 packets, in result such
>> traffic was allowed.
>>
>> Signed-off-by: Piotr Sawicki <p.sawicki2 at partner.samsung.com>
> 
> Acked-by: Casey Schaufler <casey at schaufler-ca.com
> 
> I have added this to git://github.com/cschaufler/next-smack#smack-for-4.19
> after doing a little whitespace clean-up and removal of unnecessary braces.

I see that the wrong version of the patch was applied. It should be a 
version taken from the email titled "[PATCH RFC] Smack: Fix handling of 
IPv4 traffic received by PF_INET6 sockets" (10th of July 2018). The 
family variable should be used also in netlbl_skbuff_getattr(), 
netlbl_skbuff_err and in audit structure.


>> ---
>>    security/smack/smack_lsm.c | 12 ++++++++----
>>    1 file changed, 8 insertions(+), 4 deletions(-)
>>
>> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
>> index 19de675..1315de4 100644
>> --- a/security/smack/smack_lsm.c
>> +++ b/security/smack/smack_lsm.c
>> @@ -3924,15 +3924,19 @@ static int smack_socket_sock_rcv_skb(struct sock
>> *sk, struct sk_buff *skb)
>>    	struct smack_known *skp = NULL;
>>    	int rc = 0;
>>    	struct smk_audit_info ad;
>> +	u16 family = sk->sk_family;
>>    #ifdef CONFIG_AUDIT
>>    	struct lsm_network_audit net;
>>    #endif
>>    #if IS_ENABLED(CONFIG_IPV6)
>>    	struct sockaddr_in6 sadd;
>>    	int proto;
>> +
>> +	if (family == PF_INET6 && skb->protocol == htons(ETH_P_IP))
>> +		family = PF_INET;
>>    #endif /* CONFIG_IPV6 */
>>
>> -	switch (sk->sk_family) {
>> +	switch (family) {
>>    	case PF_INET:
>>    #ifdef CONFIG_SECURITY_SMACK_NETFILTER
>>    		/*
>> @@ -3950,7 +3954,7 @@ static int smack_socket_sock_rcv_skb(struct sock
>> *sk, struct sk_buff *skb)
>>    		 */
>>    		netlbl_secattr_init(&secattr);
>>
>> -		rc = netlbl_skbuff_getattr(skb, sk->sk_family, &secattr);
>> +		rc = netlbl_skbuff_getattr(skb, family, &secattr);
>>    		if (rc == 0)
>>    			skp = smack_from_secattr(&secattr, ssp);
>>    		else
>> @@ -3963,7 +3967,7 @@ static int smack_socket_sock_rcv_skb(struct sock
>> *sk, struct sk_buff *skb)
>>    #endif
>>    #ifdef CONFIG_AUDIT
>>    		smk_ad_init_net(&ad, __func__, LSM_AUDIT_DATA_NET, &net);
>> -		ad.a.u.net->family = sk->sk_family;
>> +		ad.a.u.net->family = family;
>>    		ad.a.u.net->netif = skb->skb_iif;
>>    		ipv4_skb_to_auditdata(skb, &ad.a, NULL);
>>    #endif
>> @@ -3977,7 +3981,7 @@ static int smack_socket_sock_rcv_skb(struct sock
>> *sk, struct sk_buff *skb)
>>    		rc = smk_bu_note("IPv4 delivery", skp, ssp->smk_in,
>>    					MAY_WRITE, rc);
>>    		if (rc != 0)
>> -			netlbl_skbuff_err(skb, sk->sk_family, rc, 0);
>> +			netlbl_skbuff_err(skb, family, rc, 0);
>>    		break;
>>    #if IS_ENABLED(CONFIG_IPV6)
>>    	case PF_INET6:
> 
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