linux-toradex.git/net/ipv4, branch v3.14.19

tcp: Fix integer-overflow in TCP vegas

2014-08-14T01:38:24+00:00

[ Upstream commit 1f74e613ded11517db90b2bd57e9464d9e0fb161 ]

In vegas we do a multiplication of the cwnd and the rtt. This
may overflow and thus their result is stored in a u64. However, we first
need to cast the cwnd so that actually 64-bit arithmetic is done.

Then, we need to do do_div to allow this to be used on 32-bit arches.

Cc: Stephen Hemminger 
Cc: Neal Cardwell 
Cc: Eric Dumazet 
Cc: David Laight 
Cc: Doug Leith 
Fixes: 8d3a564da34e (tcp: tcp_vegas cong avoid fix)
Signed-off-by: Christoph Paasch 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

tcp: Fix integer-overflows in TCP veno

2014-08-14T01:38:23+00:00

[ Upstream commit 45a07695bc64b3ab5d6d2215f9677e5b8c05a7d0 ]

In veno we do a multiplication of the cwnd and the rtt. This
may overflow and thus their result is stored in a u64. However, we first
need to cast the cwnd so that actually 64-bit arithmetic is done.

A first attempt at fixing 76f1017757aa0 ([TCP]: TCP Veno congestion
control) was made by 159131149c2 (tcp: Overflow bug in Vegas), but it
failed to add the required cast in tcp_veno_cong_avoid().

Fixes: 76f1017757aa0 ([TCP]: TCP Veno congestion control)
Signed-off-by: Christoph Paasch 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ip_tunnel(ipv4): fix tunnels with "local any remote $remote_ip"

2014-08-14T01:38:23+00:00

[ Upstream commit 95cb5745983c222867cc9ac593aebb2ad67d72c0 ]

Ipv4 tunnels created with "local any remote $ip" didn't work properly since
7d442fab0 (ipv4: Cache dst in tunnels). 99% of packets sent via those tunnels
had src addr = 0.0.0.0. That was because only dst_entry was cached, although
fl4.saddr has to be cached too. Every time ip_tunnel_xmit used cached dst_entry
(tunnel_rtable_get returned non-NULL), fl4.saddr was initialized with
tnl_params->saddr (= 0 in our case), and wasn't changed until iptunnel_xmit().

This patch adds saddr to ip_tunnel->dst_cache, fixing this issue.

Reported-by: Sergey Popov 
Signed-off-by: Dmitry Popov 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ip: make IP identifiers less predictable

2014-08-14T01:38:23+00:00

[ Upstream commit 04ca6973f7c1a0d8537f2d9906a0cf8e69886d75 ]

In "Counting Packets Sent Between Arbitrary Internet Hosts", Jeffrey and
Jedidiah describe ways exploiting linux IP identifier generation to
infer whether two machines are exchanging packets.

With commit 73f156a6e8c1 ("inetpeer: get rid of ip_id_count"), we
changed IP id generation, but this does not really prevent this
side-channel technique.

This patch adds a random amount of perturbation so that IP identifiers
for a given destination [1] are no longer monotonically increasing after
an idle period.

Note that prandom_u32_max(1) returns 0, so if generator is used at most
once per jiffy, this patch inserts no hole in the ID suite and do not
increase collision probability.

This is jiffies based, so in the worst case (HZ=1000), the id can
rollover after ~65 seconds of idle time, which should be fine.

We also change the hash used in __ip_select_ident() to not only hash
on daddr, but also saddr and protocol, so that ICMP probes can not be
used to infer information for other protocols.

For IPv6, adds saddr into the hash as well, but not nexthdr.

If I ping the patched target, we can see ID are now hard to predict.

21:57:11.008086 IP (...)
    A > target: ICMP echo request, seq 1, length 64
21:57:11.010752 IP (... id 2081 ...)
    target > A: ICMP echo reply, seq 1, length 64

21:57:12.013133 IP (...)
    A > target: ICMP echo request, seq 2, length 64
21:57:12.015737 IP (... id 3039 ...)
    target > A: ICMP echo reply, seq 2, length 64

21:57:13.016580 IP (...)
    A > target: ICMP echo request, seq 3, length 64
21:57:13.019251 IP (... id 3437 ...)
    target > A: ICMP echo reply, seq 3, length 64

[1] TCP sessions uses a per flow ID generator not changed by this patch.

Signed-off-by: Eric Dumazet 
Reported-by: Jeffrey Knockel 
Reported-by: Jedidiah R. Crandall 
Cc: Willy Tarreau 
Cc: Hannes Frederic Sowa 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

inetpeer: get rid of ip_id_count

2014-08-14T01:38:23+00:00

[ Upstream commit 73f156a6e8c1074ac6327e0abd1169e95eb66463 ]

Ideally, we would need to generate IP ID using a per destination IP
generator.

linux kernels used inet_peer cache for this purpose, but this had a huge
cost on servers disabling MTU discovery.

1) each inet_peer struct consumes 192 bytes

2) inetpeer cache uses a binary tree of inet_peer structs,
   with a nominal size of ~66000 elements under load.

3) lookups in this tree are hitting a lot of cache lines, as tree depth
   is about 20.

4) If server deals with many tcp flows, we have a high probability of
   not finding the inet_peer, allocating a fresh one, inserting it in
   the tree with same initial ip_id_count, (cf secure_ip_id())

5) We garbage collect inet_peer aggressively.

IP ID generation do not have to be 'perfect'

Goal is trying to avoid duplicates in a short period of time,
so that reassembly units have a chance to complete reassembly of
fragments belonging to one message before receiving other fragments
with a recycled ID.

We simply use an array of generators, and a Jenkin hash using the dst IP
as a key.

ipv6_select_ident() is put back into net/ipv6/ip6_output.c where it
belongs (it is only used from this file)

secure_ip_id() and secure_ipv6_id() no longer are needed.

Rename ip_select_ident_more() to ip_select_ident_segs() to avoid
unnecessary decrement/increment of the number of segments.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv4: fix buffer overflow in ip_options_compile()

2014-07-28T15:06:01+00:00

[ Upstream commit 10ec9472f05b45c94db3c854d22581a20b97db41 ]

There is a benign buffer overflow in ip_options_compile spotted by
AddressSanitizer[1] :

Its benign because we always can access one extra byte in skb->head
(because header is followed by struct skb_shared_info), and in this case
this byte is not even used.

[28504.910798] ==================================================================
[28504.912046] AddressSanitizer: heap-buffer-overflow in ip_options_compile
[28504.913170] Read of size 1 by thread T15843:
[28504.914026]  [] ip_options_compile+0x121/0x9c0
[28504.915394]  [] ip_options_get_from_user+0xad/0x120
[28504.916843]  [] do_ip_setsockopt.isra.15+0x8df/0x1630
[28504.918175]  [] ip_setsockopt+0x30/0xa0
[28504.919490]  [] tcp_setsockopt+0x5b/0x90
[28504.920835]  [] sock_common_setsockopt+0x5f/0x70
[28504.922208]  [] SyS_setsockopt+0xa2/0x140
[28504.923459]  [] system_call_fastpath+0x16/0x1b
[28504.924722]
[28504.925106] Allocated by thread T15843:
[28504.925815]  [] ip_options_get_from_user+0x35/0x120
[28504.926884]  [] do_ip_setsockopt.isra.15+0x8df/0x1630
[28504.927975]  [] ip_setsockopt+0x30/0xa0
[28504.929175]  [] tcp_setsockopt+0x5b/0x90
[28504.930400]  [] sock_common_setsockopt+0x5f/0x70
[28504.931677]  [] SyS_setsockopt+0xa2/0x140
[28504.932851]  [] system_call_fastpath+0x16/0x1b
[28504.934018]
[28504.934377] The buggy address ffff880026382828 is located 0 bytes to the right
[28504.934377]  of 40-byte region [ffff880026382800, ffff880026382828)
[28504.937144]
[28504.937474] Memory state around the buggy address:
[28504.938430]  ffff880026382300: ........ rrrrrrrr rrrrrrrr rrrrrrrr
[28504.939884]  ffff880026382400: ffffffff rrrrrrrr rrrrrrrr rrrrrrrr
[28504.941294]  ffff880026382500: .....rrr rrrrrrrr rrrrrrrr rrrrrrrr
[28504.942504]  ffff880026382600: ffffffff rrrrrrrr rrrrrrrr rrrrrrrr
[28504.943483]  ffff880026382700: ffffffff rrrrrrrr rrrrrrrr rrrrrrrr
[28504.944511] >ffff880026382800: .....rrr rrrrrrrr rrrrrrrr rrrrrrrr
[28504.945573]                         ^
[28504.946277]  ffff880026382900: ffffffff rrrrrrrr rrrrrrrr rrrrrrrr
[28505.094949]  ffff880026382a00: ffffffff rrrrrrrr rrrrrrrr rrrrrrrr
[28505.096114]  ffff880026382b00: ffffffff rrrrrrrr rrrrrrrr rrrrrrrr
[28505.097116]  ffff880026382c00: ffffffff rrrrrrrr rrrrrrrr rrrrrrrr
[28505.098472]  ffff880026382d00: ffffffff rrrrrrrr rrrrrrrr rrrrrrrr
[28505.099804] Legend:
[28505.100269]  f - 8 freed bytes
[28505.100884]  r - 8 redzone bytes
[28505.101649]  . - 8 allocated bytes
[28505.102406]  x=1..7 - x allocated bytes + (8-x) redzone bytes
[28505.103637] ==================================================================

[1] https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net-gre-gro: Fix a bug that breaks the forwarding path

2014-07-28T15:06:01+00:00

[ Upstream commit c3caf1192f904de2f1381211f564537235d50de3 ]

Fixed a bug that was introduced by my GRE-GRO patch
(bf5a755f5e9186406bbf50f4087100af5bd68e40 net-gre-gro: Add GRE
support to the GRO stack) that breaks the forwarding path
because various GSO related fields were not set. The bug will
cause on the egress path either the GSO code to fail, or a
GRE-TSO capable (NETIF_F_GSO_GRE) NICs to choke. The following
fix has been tested for both cases.

Signed-off-by: H.K. Jerry Chu 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

tcp: fix false undo corner cases

2014-07-28T15:06:00+00:00

[ Upstream commit 6e08d5e3c8236e7484229e46fdf92006e1dd4c49 ]

The undo code assumes that, upon entering loss recovery, TCP
1) always retransmit something
2) the retransmission never fails locally (e.g., qdisc drop)

so undo_marker is set in tcp_enter_recovery() and undo_retrans is
incremented only when tcp_retransmit_skb() is successful.

When the assumption is broken because TCP's cwnd is too small to
retransmit or the retransmit fails locally. The next (DUP)ACK
would incorrectly revert the cwnd and the congestion state in
tcp_try_undo_dsack() or tcp_may_undo(). Subsequent (DUP)ACKs
may enter the recovery state. The sender repeatedly enter and
(incorrectly) exit recovery states if the retransmits continue to
fail locally while receiving (DUP)ACKs.

The fix is to initialize undo_retrans to -1 and start counting on
the first retransmission. Always increment undo_retrans even if the
retransmissions fail locally because they couldn't cause DSACKs to
undo the cwnd reduction.

Signed-off-by: Yuchung Cheng 
Signed-off-by: Neal Cardwell 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

igmp: fix the problem when mc leave group

2014-07-28T15:06:00+00:00

[ Upstream commit 52ad353a5344f1f700c5b777175bdfa41d3cd65a ]

The problem was triggered by these steps:

1) create socket, bind and then setsockopt for add mc group.
   mreq.imr_multiaddr.s_addr = inet_addr("255.0.0.37");
   mreq.imr_interface.s_addr = inet_addr("192.168.1.2");
   setsockopt(sockfd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq));

2) drop the mc group for this socket.
   mreq.imr_multiaddr.s_addr = inet_addr("255.0.0.37");
   mreq.imr_interface.s_addr = inet_addr("0.0.0.0");
   setsockopt(sockfd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));

3) and then drop the socket, I found the mc group was still used by the dev:

   netstat -g

   Interface       RefCnt Group
   --------------- ------ ---------------------
   eth2		   1	  255.0.0.37

Normally even though the IP_DROP_MEMBERSHIP return error, the mc group still need
to be released for the netdev when drop the socket, but this process was broken when
route default is NULL, the reason is that:

The ip_mc_leave_group() will choose the in_dev by the imr_interface.s_addr, if input addr
is NULL, the default route dev will be chosen, then the ifindex is got from the dev,
then polling the inet->mc_list and return -ENODEV, but if the default route dev is NULL,
the in_dev and ifIndex is both NULL, when polling the inet->mc_list, the mc group will be
released from the mc_list, but the dev didn't dec the refcnt for this mc group, so
when dropping the socket, the mc_list is NULL and the dev still keep this group.

v1->v2: According Hideaki's suggestion, we should align with IPv6 (RFC3493) and BSDs,
	so I add the checking for the in_dev before polling the mc_list, make sure when
	we remove the mc group, dec the refcnt to the real dev which was using the mc address.
	The problem would never happened again.

Signed-off-by: Ding Tianhong 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv4: icmp: Fix pMTU handling for rare case

2014-07-28T15:06:00+00:00

[ Upstream commit 68b7107b62983f2cff0948292429d5f5999df096 ]

Some older router implementations still send Fragmentation Needed
errors with the Next-Hop MTU field set to zero. This is explicitly
described as an eventuality that hosts must deal with by the
standard (RFC 1191) since older standards specified that those
bits must be zero.

Linux had a generic (for all of IPv4) implementation of the algorithm
described in the RFC for searching a list of MTU plateaus for a good
value. Commit 46517008e116 ("ipv4: Kill ip_rt_frag_needed().")
removed this as part of the changes to remove the routing cache.
Subsequently any Fragmentation Needed packet with a zero Next-Hop
MTU has been discarded without being passed to the per-protocol
handlers or notifying userspace for raw sockets.

When there is a router which does not implement RFC 1191 on an
MTU limited path then this results in stalled connections since
large packets are discarded and the local protocols are not
notified so they never attempt to lower the pMTU.

One example I have seen is an OpenBSD router terminating IPSec
tunnels. It's worth pointing out that this case is distinct from
the BSD 4.2 bug which incorrectly calculated the Next-Hop MTU
since the commit in question dismissed that as a valid concern.

All of the per-protocols handlers implement the simple approach from
RFC 1191 of immediately falling back to the minimum value. Although
this is sub-optimal it is vastly preferable to connections hanging
indefinitely.

Remove the Next-Hop MTU != 0 check and allow such packets
to follow the normal path.

Fixes: 46517008e116 ("ipv4: Kill ip_rt_frag_needed().")
Signed-off-by: Edward Allcutt 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman