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tipc: only accept encrypted MSG_CRYPTO msgs

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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.

Note that this is also a supplementary fix to CVE-2021-43267 that
can be triggered by an unencrypted malicious MSG_CRYPTO msg.

Fixes: 1ef6f7c939 ("tipc: add automatic session key exchange")
Acked-by: Ying Xue <ying.xue@windriver.com>
Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Xin Long 2021-11-15 07:45:24 -05:00 committed by David S. Miller
parent 6def480181
commit 271351d255
1 changed files with 5 additions and 2 deletions
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7
net/tipc/link.c
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@ -1298,8 +1298,11 @@ static bool tipc_data_input(struct tipc_link *l, struct sk_buff *skb,
return false; return false;
#ifdef CONFIG_TIPC_CRYPTO #ifdef CONFIG_TIPC_CRYPTO
case MSG_CRYPTO: case MSG_CRYPTO:
tipc_crypto_msg_rcv(l->net, skb); if (TIPC_SKB_CB(skb)->decrypted) {
return true; tipc_crypto_msg_rcv(l->net, skb);
return true;
}
fallthrough;
#endif #endif
default: default:
pr_warn("Dropping received illegal msg type\n"); pr_warn("Dropping received illegal msg type\n");