[ Upstream commit 469aceddfa3ed16e17ee30533fae45e90f62efd8 ]
Toshiaki pointed out that we now have two very similar functions to extract
the L3 protocol number in the presence of VLAN tags. And Daniel pointed out
that the unbounded parsing loop makes it possible for maliciously crafted
packets to loop through potentially hundreds of tags.
Fix both of these issues by consolidating the two parsing functions and
limiting the VLAN tag parsing to a max depth of 8 tags. As part of this,
switch over __vlan_get_protocol() to use skb_header_pointer() instead of
pskb_may_pull(), to avoid the possible side effects of the latter and keep
the skb pointer 'const' through all the parsing functions.
v2:
- Use limit of 8 tags instead of 32 (matching XMIT_RECURSION_LIMIT)
Reported-by: Toshiaki Makita <toshiaki.makita1@gmail.com>
Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Fixes: d7bf2ebebc2b ("sched: consistently handle layer3 header accesses in the presence of VLANs")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit d7bf2ebebc2bd61ab95e2a8e33541ef282f303d4 ]
There are a couple of places in net/sched/ that check skb->protocol and act
on the value there. However, in the presence of VLAN tags, the value stored
in skb->protocol can be inconsistent based on whether VLAN acceleration is
enabled. The commit quoted in the Fixes tag below fixed the users of
skb->protocol to use a helper that will always see the VLAN ethertype.
However, most of the callers don't actually handle the VLAN ethertype, but
expect to find the IP header type in the protocol field. This means that
things like changing the ECN field, or parsing diffserv values, stops
working if there's a VLAN tag, or if there are multiple nested VLAN
tags (QinQ).
To fix this, change the helper to take an argument that indicates whether
the caller wants to skip the VLAN tags or not. When skipping VLAN tags, we
make sure to skip all of them, so behaviour is consistent even in QinQ
mode.
To make the helper usable from the ECN code, move it to if_vlan.h instead
of pkt_sched.h.
v3:
- Remove empty lines
- Move vlan variable definitions inside loop in skb_protocol()
- Also use skb_protocol() helper in IP{,6}_ECN_decapsulate() and
bpf_skb_ecn_set_ce()
v2:
- Use eth_type_vlan() helper in skb_protocol()
- Also fix code that reads skb->protocol directly
- Change a couple of 'if/else if' statements to switch constructs to avoid
calling the helper twice
Reported-by: Ilya Ponetayev <i.ponetaev@ndmsystems.com>
Fixes: d8b9605d2697 ("net: sched: fix skb->protocol use in case of accelerated vlan path")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Toke Høiland-Jørgensen