netdev - Re: [PATCH v1 net 1/4] llc: Check netns in llc_dgram

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Message-ID: <e7def8ab99c2a27176e0861117efbe4797c908eb.camel@redhat.com>
Date: Tue, 18 Jul 2023 12:34:47 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Kuniyuki Iwashima <kuniyu@...zon.com>, "David S. Miller"
	 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski
	 <kuba@...nel.org>, Roopa Prabhu <roopa@...dia.com>, Nikolay Aleksandrov
	 <razor@...ckwall.org>
Cc: "Eric W. Biederman" <ebiederm@...ssion.com>, Harry Coin
	 <hcoin@...etfountain.com>, Kuniyuki Iwashima <kuni1840@...il.com>, 
	netdev@...r.kernel.org
Subject: Re: [PATCH v1 net 1/4] llc: Check netns in llc_dgram_match().

Hi,

the series LGTM, I have only a couple of (very) minor nit, see below...

On Fri, 2023-07-14 at 19:13 -0700, Kuniyuki Iwashima wrote:
> We will remove this restriction in llc_rcv() in the following patch,

s/following patch/soon/, as the following patch will not do that ;)

> which means that the protocol handler must be aware of netns.
> 
> 	if (!net_eq(dev_net(dev), &init_net))
> 		goto drop;
> 
> llc_rcv() fetches llc_type_handlers[llc_pdu_type(skb) - 1] and calls it
> if not NULL.
> 
> If the PDU type is LLC_DEST_SAP, llc_sap_handler() is called to pass skb
> to corresponding sockets.  Then, we must look up a proper socket in the
> same netns with skb->dev.
> 
> If the destination is a multicast address, llc_sap_handler() calls
> llc_sap_mcast().  It calculates a hash based on DSAP and skb->dev->ifindex,
> iterates on a socket list, and calls llc_mcast_match() to check if the
> socket is the correct destination.  Then, llc_mcast_match() checks if
> skb->dev matches with llc_sk(sk)->dev.  So, we need not check netns here.
> 
> OTOH, if the destination is a unicast address, llc_sap_handler() calls
> llc_lookup_dgram() to look up a socket, but it does not check the netns.
> 
> Therefore, we need to add netns check in llc_lookup_dgram().
> 
> Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
> ---
>  net/llc/llc_sap.c | 17 ++++++++++-------
>  1 file changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/net/llc/llc_sap.c b/net/llc/llc_sap.c
> index 6805ce43a055..5c83fca3acd5 100644
> --- a/net/llc/llc_sap.c
> +++ b/net/llc/llc_sap.c
> @@ -294,13 +294,15 @@ static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb,
>  
>  static inline bool llc_dgram_match(const struct llc_sap *sap,
>  				   const struct llc_addr *laddr,
> -				   const struct sock *sk)
> +				   const struct sock *sk,
> +				   const struct net *net)
>  {
>       struct llc_sock *llc = llc_sk(sk);
>  
>       return sk->sk_type == SOCK_DGRAM &&
> -	  llc->laddr.lsap == laddr->lsap &&
> -	  ether_addr_equal(llc->laddr.mac, laddr->mac);
> +	     net_eq(sock_net(sk), net) &&
> +	     llc->laddr.lsap == laddr->lsap &&
> +	     ether_addr_equal(llc->laddr.mac, laddr->mac);
>  }
>  
>  /**
> @@ -312,7 +314,8 @@ static inline bool llc_dgram_match(const struct llc_sap *sap,
>   *	mac, and local sap. Returns pointer for socket found, %NULL otherwise.
>   */

As this function has doxygen documentation, you should additionally
document the 'net' argument.

Thanks,

Paolo