linux-toradex.git/net/ipv6/ip6_output.c, branch v4.4.90

net: account for current skb length when deciding about UFO

2017-08-13T02:29:09+00:00

commit a5cb659bbc1c8644efa0c3138a757a1e432a4880 upstream.

Our customer encountered stuck NFS writes for blocks starting at specific
offsets w.r.t. page boundary caused by networking stack sending packets via
UFO enabled device with wrong checksum. The problem can be reproduced by
composing a long UDP datagram from multiple parts using MSG_MORE flag:

  sendto(sd, buff, 1000, MSG_MORE, ...);
  sendto(sd, buff, 1000, MSG_MORE, ...);
  sendto(sd, buff, 3000, 0, ...);

Assume this packet is to be routed via a device with MTU 1500 and
NETIF_F_UFO enabled. When second sendto() gets into __ip_append_data(),
this condition is tested (among others) to decide whether to call
ip_ufo_append_data():

  ((length + fragheaderlen) > mtu) || (skb && skb_is_gso(skb))

At the moment, we already have skb with 1028 bytes of data which is not
marked for GSO so that the test is false (fragheaderlen is usually 20).
Thus we append second 1000 bytes to this skb without invoking UFO. Third
sendto(), however, has sufficient length to trigger the UFO path so that we
end up with non-UFO skb followed by a UFO one. Later on, udp_send_skb()
uses udp_csum() to calculate the checksum but that assumes all fragments
have correct checksum in skb->csum which is not true for UFO fragments.

When checking against MTU, we need to add skb->len to length of new segment
if we already have a partially filled skb and fragheaderlen only if there
isn't one.

In the IPv6 case, skb can only be null if this is the first segment so that
we have to use headersize (length of the first IPv6 header) rather than
fragheaderlen (length of IPv6 header of further fragments) for skb == NULL.

Fixes: e89e9cf539a2 ("[IPv4/IPv6]: UFO Scatter-gather approach")
Fixes: e4c5e13aa45c ("ipv6: Should use consistent conditional judgement for
	ip6 fragment between __ip6_append_data and ip6_finish_output")
Signed-off-by: Michal Kubecek 
Acked-by: Vlad Yasevich 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

udp: consistently apply ufo or fragmentation

2017-08-13T02:29:09+00:00

[ Upstream commit 85f1bd9a7b5a79d5baa8bf44af19658f7bf77bfa ]

When iteratively building a UDP datagram with MSG_MORE and that
datagram exceeds MTU, consistently choose UFO or fragmentation.

Once skb_is_gso, always apply ufo. Conversely, once a datagram is
split across multiple skbs, do not consider ufo.

Sendpage already maintains the first invariant, only add the second.
IPv6 does not have a sendpage implementation to modify.

A gso skb must have a partial checksum, do not follow sk_no_check_tx
in udp_send_skb.

Found by syzkaller.

Fixes: e89e9cf539a2 ("[IPv4/IPv6]: UFO Scatter-gather approach")
Reported-by: Andrey Konovalov 
Signed-off-by: Willem de Bruijn 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

revert "net: account for current skb length when deciding about UFO"

2017-08-13T02:29:09+00:00

This reverts commit ef09c9ff343122a0b245416066992d096416ff19 which is
commit a5cb659bbc1c8644efa0c3138a757a1e432a4880 upstream as it causes
merge issues with later patches that are much more important...

Cc: Michal Kubecek 
Cc: Vlad Yasevich 
Cc: David S. Miller 
Cc: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

net: account for current skb length when deciding about UFO

2017-08-11T16:08:59+00:00

[ Upstream commit a5cb659bbc1c8644efa0c3138a757a1e432a4880 ]

Our customer encountered stuck NFS writes for blocks starting at specific
offsets w.r.t. page boundary caused by networking stack sending packets via
UFO enabled device with wrong checksum. The problem can be reproduced by
composing a long UDP datagram from multiple parts using MSG_MORE flag:

  sendto(sd, buff, 1000, MSG_MORE, ...);
  sendto(sd, buff, 1000, MSG_MORE, ...);
  sendto(sd, buff, 3000, 0, ...);

Assume this packet is to be routed via a device with MTU 1500 and
NETIF_F_UFO enabled. When second sendto() gets into __ip_append_data(),
this condition is tested (among others) to decide whether to call
ip_ufo_append_data():

  ((length + fragheaderlen) > mtu) || (skb && skb_is_gso(skb))

At the moment, we already have skb with 1028 bytes of data which is not
marked for GSO so that the test is false (fragheaderlen is usually 20).
Thus we append second 1000 bytes to this skb without invoking UFO. Third
sendto(), however, has sufficient length to trigger the UFO path so that we
end up with non-UFO skb followed by a UFO one. Later on, udp_send_skb()
uses udp_csum() to calculate the checksum but that assumes all fragments
have correct checksum in skb->csum which is not true for UFO fragments.

When checking against MTU, we need to add skb->len to length of new segment
if we already have a partially filled skb and fragheaderlen only if there
isn't one.

In the IPv6 case, skb can only be null if this is the first segment so that
we have to use headersize (length of the first IPv6 header) rather than
fragheaderlen (length of IPv6 header of further fragments) for skb == NULL.

Fixes: e89e9cf539a2 ("[IPv4/IPv6]: UFO Scatter-gather approach")
Fixes: e4c5e13aa45c ("ipv6: Should use consistent conditional judgement for
	ip6 fragment between __ip6_append_data and ip6_finish_output")
Signed-off-by: Michal Kubecek 
Acked-by: Vlad Yasevich 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

ipv6: Don't increase IPSTATS_MIB_FRAGFAILS twice in ip6_fragment()

2017-08-11T16:08:53+00:00

[ Upstream commit afce615aaabfbaad02550e75c0bec106dafa1adf ]

RFC 2465 defines ipv6IfStatsOutFragFails as:

	"The number of IPv6 datagrams that have been discarded
	 because they needed to be fragmented at this output
	 interface but could not be."

The existing implementation, instead, would increase the counter
twice in case we fail to allocate room for single fragments:
once for the fragment, once for the datagram.

This didn't look intentional though. In one of the two affected
affected failure paths, the double increase was simply a result
of a new 'goto fail' statement, introduced to avoid a skb leak.
The other path appears to be affected since at least 2.6.12-rc2.

Reported-by: Sabrina Dubroca 
Fixes: 1d325d217c7f ("ipv6: ip6_fragment: fix headroom tests and skb leak")
Signed-off-by: Stefano Brivio 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv6: Should use consistent conditional judgement for ip6 fragment between __ip6_append_data and ip6_finish_output

2017-08-07T02:19:44+00:00

[ Upstream commit e4c5e13aa45c23692e4acf56f0b3533f328199b2 ]

There is an inconsistent conditional judgement between __ip6_append_data
and ip6_finish_output functions, the variable length in __ip6_append_data
just include the length of application's payload and udp6 header, don't
include the length of ipv6 header, but in ip6_finish_output use
(skb->len > ip6_skb_dst_mtu(skb)) as judgement, and skb->len include the
length of ipv6 header.

That causes some particular application's udp6 payloads whose length are
between (MTU - IPv6 Header) and MTU were fragmented by ip6_fragment even
though the rst->dev support UFO feature.

Add the length of ipv6 header to length in __ip6_append_data to keep
consistent conditional judgement as ip6_finish_output for ip6 fragment.

Signed-off-by: Zheng Li 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

ipv6: release dst on error in ip6_dst_lookup_tail

2017-07-05T12:37:13+00:00

commit 00ea1ceebe0d9f2dc1cc2b7bd575a00100c27869 upstream.

If ip6_dst_lookup_tail has acquired a dst and fails the IPv4-mapped
check, release the dst before returning an error.

Fixes: ec5e3b0a1d41 ("ipv6: Inhibit IPv4-mapped src address on the wire.")
Signed-off-by: Willem de Bruijn 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller 
Cc: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

ipv6: Inhibit IPv4-mapped src address on the wire.

2017-06-17T04:39:35+00:00

[ Upstream commit ec5e3b0a1d41fbda0cc33a45bc9e54e91d9d12c7 ]

This patch adds a check for the problematic case of an IPv4-mapped IPv6
source address and a destination address that is neither an IPv4-mapped
IPv6 address nor in6addr_any, and returns an appropriate error. The
check in done before returning from looking up the route.

Signed-off-by: Jonathan T. Leighton 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

ipv6: fix out of bound writes in __ip6_append_data()

2017-06-07T10:05:58+00:00

[ Upstream commit 232cd35d0804cc241eb887bb8d4d9b3b9881c64a ]

Andrey Konovalov and idaifish@gmail.com reported crashes caused by
one skb shared_info being overwritten from __ip6_append_data()

Andrey program lead to following state :

copy -4200 datalen 2000 fraglen 2040
maxfraglen 2040 alloclen 2048 transhdrlen 0 offset 0 fraggap 6200

The skb_copy_and_csum_bits(skb_prev, maxfraglen, data + transhdrlen,
fraggap, 0); is overwriting skb->head and skb_shared_info

Since we apparently detect this rare condition too late, move the
code earlier to even avoid allocating skb and risking crashes.

Once again, many thanks to Andrey and syzkaller team.

Signed-off-by: Eric Dumazet 
Reported-by: Andrey Konovalov 
Tested-by: Andrey Konovalov 
Reported-by: 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv6: Check ip6_find_1stfragopt() return value properly.

2017-06-07T10:05:58+00:00

[ Upstream commit 7dd7eb9513bd02184d45f000ab69d78cb1fa1531 ]

Do not use unsigned variables to see if it returns a negative
error or not.

Fixes: 2423496af35d ("ipv6: Prevent overrun when parsing v6 header options")
Reported-by: Julia Lawall 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman