linux-stable.git/net/core/skbuff.c, branch v5.4

net/sched: fix corrupted L2 header with MPLS 'push' and 'pop' actions

2019-10-16T00:14:48+00:00

the following script:

 # tc qdisc add dev eth0 clsact
 # tc filter add dev eth0 egress protocol ip matchall \
 > action mpls push protocol mpls_uc label 0x355aa bos 1

causes corruption of all IP packets transmitted by eth0. On TC egress, we
can't rely on the value of skb->mac_len, because it's 0 and a MPLS 'push'
operation will result in an overwrite of the first 4 octets in the packet
L2 header (e.g. the Destination Address if eth0 is an Ethernet); the same
error pattern is present also in the MPLS 'pop' operation. Fix this error
in act_mpls data plane, computing 'mac_len' as the difference between the
network header and the mac header (when not at TC ingress), and use it in
MPLS 'push'/'pop' core functions.

v2: unbreak 'make htmldocs' because of missing documentation of 'mac_len'
    in skb_mpls_pop(), reported by kbuild test robot

CC: Lorenzo Bianconi 
Fixes: 2a2ea50870ba ("net: sched: add mpls manipulation actions to TC")
Reviewed-by: Simon Horman 
Acked-by: John Hurley 
Signed-off-by: Davide Caratti 
Signed-off-by: David S. Miller

net: avoid errors when trying to pop MLPS header on non-MPLS packets

2019-10-16T00:14:48+00:00

the following script:

 # tc qdisc add dev eth0 clsact
 # tc filter add dev eth0 egress matchall action mpls pop

implicitly makes the kernel drop all packets transmitted by eth0, if they
don't have a MPLS header. This behavior is uncommon: other encapsulations
(like VLAN) just let the packet pass unmodified. Since the result of MPLS
'pop' operation would be the same regardless of the presence / absence of
MPLS header(s) in the original packet, we can let skb_mpls_pop() return 0
when dealing with non-MPLS packets.

For the OVS use-case, this is acceptable because __ovs_nla_copy_actions()
already ensures that MPLS 'pop' operation only occurs with packets having
an MPLS Ethernet type (and there are no other callers in current code, so
the semantic change should be ok).

v2: better documentation of use-cases for skb_mpls_pop(), thanks to Simon
    Horman

Fixes: 2a2ea50870ba ("net: sched: add mpls manipulation actions to TC")
Reviewed-by: Simon Horman 
Acked-by: John Hurley 
Signed-off-by: Davide Caratti 
Signed-off-by: David S. Miller

tcp: annotate sk->sk_rcvbuf lockless reads

2019-10-13T17:13:08+00:00

For the sake of tcp_poll(), there are few places where we fetch
sk->sk_rcvbuf while this field can change from IRQ or other cpu.

We need to add READ_ONCE() annotations, and also make sure write
sides use corresponding WRITE_ONCE() to avoid store-tearing.

Note that other transports probably need similar fixes.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

netfilter: drop bridge nf reset from nf_reset

2019-10-01T16:42:15+00:00

commit 174e23810cd31
("sk_buff: drop all skb extensions on free and skb scrubbing") made napi
recycle always drop skb extensions.  The additional skb_ext_del() that is
performed via nf_reset on napi skb recycle is not needed anymore.

Most nf_reset() calls in the stack are there so queued skb won't block
'rmmod nf_conntrack' indefinitely.

This removes the skb_ext_del from nf_reset, and renames it to a more
fitting nf_reset_ct().

In a few selected places, add a call to skb_ext_reset to make sure that
no active extensions remain.

I am submitting this for "net", because we're still early in the release
cycle.  The patch applies to net-next too, but I think the rename causes
needless divergence between those trees.

Suggested-by: Eric Dumazet 
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

sk_buff: drop all skb extensions on free and skb scrubbing

2019-09-27T18:40:19+00:00

Now that we have a 3rd extension, add a new helper that drops the
extension space and use it when we need to scrub an sk_buff.

At this time, scrubbing clears secpath and bridge netfilter data, but
retains the tc skb extension, after this patch all three get cleared.

NAPI reuse/free assumes we can only have a secpath attached to skb, but
it seems better to clear all extensions there as well.

v2: add unlikely hint (Eric Dumazet)

Fixes: 95a7233c452a ("net: openvswitch: Set OvS recirc_id from tc chain index")
Signed-off-by: Florian Westphal 
Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2019-09-15T12:17:27+00:00

Minor overlapping changes in the btusb and ixgbe drivers.

Signed-off-by: David S. Miller

net: gso: Fix skb_segment splat when splitting gso_size mangled skb having linear-headed frag_list

2019-09-07T15:58:48+00:00

Historically, support for frag_list packets entering skb_segment() was
limited to frag_list members terminating on exact same gso_size
boundaries. This is verified with a BUG_ON since commit 89319d3801d1
("net: Add frag_list support to skb_segment"), quote:

    As such we require all frag_list members terminate on exact MSS
    boundaries.  This is checked using BUG_ON.
    As there should only be one producer in the kernel of such packets,
    namely GRO, this requirement should not be difficult to maintain.

However, since commit 6578171a7ff0 ("bpf: add bpf_skb_change_proto helper"),
the "exact MSS boundaries" assumption no longer holds:
An eBPF program using bpf_skb_change_proto() DOES modify 'gso_size', but
leaves the frag_list members as originally merged by GRO with the
original 'gso_size'. Example of such programs are bpf-based NAT46 or
NAT64.

This lead to a kernel BUG_ON for flows involving:
 - GRO generating a frag_list skb
 - bpf program performing bpf_skb_change_proto() or bpf_skb_adjust_room()
 - skb_segment() of the skb

See example BUG_ON reports in [0].

In commit 13acc94eff12 ("net: permit skb_segment on head_frag frag_list skb"),
skb_segment() was modified to support the "gso_size mangling" case of
a frag_list GRO'ed skb, but *only* for frag_list members having
head_frag==true (having a page-fragment head).

Alas, GRO packets having frag_list members with a linear kmalloced head
(head_frag==false) still hit the BUG_ON.

This commit adds support to skb_segment() for a 'head_skb' packet having
a frag_list whose members are *non* head_frag, with gso_size mangled, by
disabling SG and thus falling-back to copying the data from the given
'head_skb' into the generated segmented skbs - as suggested by Willem de
Bruijn [1].

Since this approach involves the penalty of skb_copy_and_csum_bits()
when building the segments, care was taken in order to enable this
solution only when required:
 - untrusted gso_size, by testing SKB_GSO_DODGY is set
   (SKB_GSO_DODGY is set by any gso_size mangling functions in
    net/core/filter.c)
 - the frag_list is non empty, its item is a non head_frag, *and* the
   headlen of the given 'head_skb' does not match the gso_size.

[0]
https://lore.kernel.org/netdev/20190826170724.25ff616f@pixies/
https://lore.kernel.org/netdev/9265b93f-253d-6b8c-f2b8-4b54eff1835c@fb.com/

[1]
https://lore.kernel.org/netdev/CA+FuTSfVsgNDi7c=GUU8nMg2hWxF2SjCNLXetHeVPdnxAW5K-w@mail.gmail.com/

Fixes: 6578171a7ff0 ("bpf: add bpf_skb_change_proto helper")
Suggested-by: Willem de Bruijn 
Cc: Daniel Borkmann 
Cc: Eric Dumazet 
Cc: Alexander Duyck 
Signed-off-by: Shmulik Ladkani 
Reviewed-by: Willem de Bruijn 
Reviewed-by: Alexander Duyck 
Signed-off-by: David S. Miller

net: openvswitch: Set OvS recirc_id from tc chain index

2019-09-06T12:59:18+00:00

Offloaded OvS datapath rules are translated one to one to tc rules,
for example the following simplified OvS rule:

recirc_id(0),in_port(dev1),eth_type(0x0800),ct_state(-trk) actions:ct(),recirc(2)

Will be translated to the following tc rule:

$ tc filter add dev dev1 ingress \
	    prio 1 chain 0 proto ip \
		flower tcp ct_state -trk \
		action ct pipe \
		action goto chain 2

Received packets will first travel though tc, and if they aren't stolen
by it, like in the above rule, they will continue to OvS datapath.
Since we already did some actions (action ct in this case) which might
modify the packets, and updated action stats, we would like to continue
the proccessing with the correct recirc_id in OvS (here recirc_id(2))
where we left off.

To support this, introduce a new skb extension for tc, which
will be used for translating tc chain to ovs recirc_id to
handle these miss cases. Last tc chain index will be set
by tc goto chain action and read by OvS datapath.

Signed-off-by: Paul Blakey 
Signed-off-by: Vlad Buslov 
Acked-by: Jiri Pirko 
Acked-by: Pravin B Shelar 
Signed-off-by: David S. Miller

net: Use skb_frag_off accessors

2019-07-30T21:21:32+00:00

Use accessor functions for skb fragment's page_offset instead
of direct references, in preparation for bvec conversion.

Signed-off-by: Jonathan Lemon 
Signed-off-by: David S. Miller

net: Rename skb_frag page to bv_page

2019-07-23T03:47:56+00:00

One step closer to turning the skb_frag_t into a bio_vec.

Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: David S. Miller