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Re: [tipc-discussion] [PATCH net] tipc: only accept encrypted MSG_CRYPTO msgs
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From: Jon M. <jm...@re...> - 2021-11-14 19:00:49
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You should mention that is a supplementary fix to CVE-2021-43267,
improving the original fix in commit
fa40d9734a57bcbfa79a280189799f76c88f7bb0 ("tipc: fix size validations
for the MSG_CRYPTO type")
///jon
On 11/14/21 08:09, Xue, Ying wrote:
> Thanks Xin! The patch looks good to me.
>
> Acked-by: Ying Xue <yin...@wi...>
>
> -----Original Message-----
> From: Xin Long <luc...@gm...>
> Sent: Saturday, November 13, 2021 3:23 AM
> To: tip...@li...
> Subject: [tipc-discussion] [PATCH net] tipc: only accept encrypted MSG_CRYPTO msgs
>
> The MSG_CRYPTO msgs are always encrypted and sent to other nodes for keys' deployment. But when receiving in peers, if those nodes do not validate it and make sure it's encrypted, one could craft a malicious MSG_CRYPTO msg to deploy its key with no need to know other nodes' keys.
>
> This patch is to do that by checking TIPC_SKB_CB(skb)->decrypted and discard it if this packet never got decrypted.
>
> Fixes: 1ef6f7c9390f ("tipc: add automatic session key exchange")
> Signed-off-by: Xin Long <luc...@gm...>
> ---
> net/tipc/link.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/net/tipc/link.c b/net/tipc/link.c index 1b7a487c8841..09ae8448f394 100644
> --- a/net/tipc/link.c
> +++ b/net/tipc/link.c
> @@ -1298,8 +1298,11 @@ static bool tipc_data_input(struct tipc_link *l, struct sk_buff *skb,
> return false;
> #ifdef CONFIG_TIPC_CRYPTO
> case MSG_CRYPTO:
> - tipc_crypto_msg_rcv(l->net, skb);
> - return true;
> + if (TIPC_SKB_CB(skb)->decrypted) {
> + tipc_crypto_msg_rcv(l->net, skb);
> + return true;
> + }
> + fallthrough;
> #endif
> default:
> pr_warn("Dropping received illegal msg type\n");
> --
> 2.27.0
>
>
>
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