Patch "smack: tcp: ipv4, fix incorrect labeling" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    smack: tcp: ipv4, fix incorrect labeling

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     smack-tcp-ipv4-fix-incorrect-labeling.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 5ca719862d8c4d2646cbc0f2adb9a524968cab30
Author: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
Date:   Wed Jun 5 15:41:50 2024 -0700

    smack: tcp: ipv4, fix incorrect labeling
    
    [ Upstream commit 2fe209d0ad2e2729f7e22b9b31a86cc3ff0db550 ]
    
    Currently, Smack mirrors the label of incoming tcp/ipv4 connections:
    when a label 'foo' connects to a label 'bar' with tcp/ipv4,
    'foo' always gets 'foo' in returned ipv4 packets. So,
    1) returned packets are incorrectly labeled ('foo' instead of 'bar')
    2) 'bar' can write to 'foo' without being authorized to write.
    
    Here is a scenario how to see this:
    
    * Take two machines, let's call them C and S,
       with active Smack in the default state
       (no settings, no rules, no labeled hosts, only builtin labels)
    
    * At S, add Smack rule 'foo bar w'
       (labels 'foo' and 'bar' are instantiated at S at this moment)
    
    * At S, at label 'bar', launch a program
       that listens for incoming tcp/ipv4 connections
    
    * From C, at label 'foo', connect to the listener at S.
       (label 'foo' is instantiated at C at this moment)
       Connection succeedes and works.
    
    * Send some data in both directions.
    * Collect network traffic of this connection.
    
    All packets in both directions are labeled with the CIPSO
    of the label 'foo'. Hence, label 'bar' writes to 'foo' without
    being authorized, and even without ever being known at C.
    
    If anybody cares: exactly the same happens with DCCP.
    
    This behavior 1st manifested in release 2.6.29.4 (see Fixes below)
    and it looks unintentional. At least, no explanation was provided.
    
    I changed returned packes label into the 'bar',
    to bring it into line with the Smack documentation claims.
    
    Signed-off-by: Konstantin Andreev <andreev@xxxxxxxxx>
    Signed-off-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index d9bff4ba7f2e..158f4df39be4 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4291,7 +4291,7 @@ static int smack_inet_conn_request(struct sock *sk, struct sk_buff *skb,
 	rcu_read_unlock();
 
 	if (hskp == NULL)
-		rc = netlbl_req_setattr(req, &skp->smk_netlabel);
+		rc = netlbl_req_setattr(req, &ssp->smk_out->smk_netlabel);
 	else
 		netlbl_req_delattr(req);