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

[Casey Schaufler]

On 7/10/2018 8:44 AM, Piotr Sawicki wrote:
> On 07/10/2018 05:21 PM, 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>
>> Looks fine from here. Do you have a simple test case?
>
> Yes, I've tested it on Tizen emulator.
>
> Tests are available here 
> https://review.tizen.org/gerrit/#/admin/projects/platform/core/test/security-tests, 
> branch nether.

Can you identify the specific test? There's quite a bit to look through.
Thank you.

>
> I'm really sorry for this mess with multiple emails.
>
>
>>> ---
>>>    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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>>
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