Re: [PATCH] ipv4: tcp: security_sk_alloc() needed for unicast_sock
flat view
From: Casey Schaufler <casey@schaufler-ca.com>
Date: 2012-08-09 21:53:07
Also in:
lkml, selinux
On 8/9/2012 2:29 PM, Eric Dumazet wrote:
On Thu, 2012-08-09 at 16:06 -0400, Eric Paris wrote:quoted
NAK. I personally think commit be9f4a44e7d41cee should be reverted until it is fixed. Let me explain what all I believe it broke and how.Suggesting to revert this commit while we have known working fixes is a bit of strange reaction.
A couple of potential short term workarounds have been identified, but no one is happy with them for the long term. That does not qualify as a "working fix" in engineering terms.
I understand you are upset, but I believe we tried to fix it.quoted
Old callchain of the creation of the 'equivalent' socket previous to the patch in question just for reference: inet_ctl_sock_create sock_create_kern __sock_create pf->create (inet_create) sk_alloc sk_prot_alloc security_sk_alloc() This WAS working properly. All of it.Nobody denies it. But acknowledge my patch uncovered a fundamental issue. What kind of 'security module' can decide to let RST packets being sent or not, on a global scale ? (one socket for the whole machine)
The short answer is "any security module that wants to". And before we go any further, I'm a little surprised that SELinux doesn't do this already.
smack_sk_alloc_security() uses smk_of_current() : What can be the meaning of smk_of_current() in the context of 'kernel' sockets...
Yes, and all of it's callers - to date - have had an appropriate value of current. It is using the API in the way it is supposed to. It is assuming a properly formed socket. You want to give it a cobbled together partial socket structure without task context. Your predecessor did not have this problem.
quoted hunk ↗ jump to hunk
Your patch tries to maintain this status quo. In fact I suggest the following one liner patch, unless you can really demonstrate what can be the meaning of providing a fake socket for these packets. This mess only happened because ip_append_data()/ip_push_pending_frames() are so complex and use an underlying socket. But this socket should not be ever used outside of its scope.diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 76dde25..ec410e0 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c@@ -1536,6 +1536,7 @@ void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr, arg->csumoffset) = csum_fold(csum_add(nskb->csum, arg->csum)); nskb->ip_summed = CHECKSUM_NONE; + skb_orphan(nskb); skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb)); ip_push_pending_frames(sk, &fl4); }