linux-toradex.git/net/ipv6, branch v3.10.54

ip: make IP identifiers less predictable

2014-08-14T01:24:15+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

2014-08-14T01:24:15+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

ipip, sit: fix ipv4_{update_pmtu,redirect} calls

2014-06-26T19:12:38+00:00

[ Upstream commit 2346829e641b804ece9ac9298136b56d9567c278 ]

ipv4_{update_pmtu,redirect} were called with tunnel's ifindex (t->dev is a
tunnel netdevice). It caused wrong route lookup and failure of pmtu update or
redirect. We should use the same ifindex that we use in ip_route_output_* in
*tunnel_xmit code. It is t->parms.link .

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

net: fix inet_getid() and ipv6_select_ident() bugs

2014-06-26T19:12:38+00:00

[ Upstream commit 39c36094d78c39e038c1e499b2364e13bce36f54 ]

I noticed we were sending wrong IPv4 ID in TCP flows when MTU discovery
is disabled.
Note how GSO/TSO packets do not have monotonically incrementing ID.

06:37:41.575531 IP (id 14227, proto: TCP (6), length: 4396)
06:37:41.575534 IP (id 14272, proto: TCP (6), length: 65212)
06:37:41.575544 IP (id 14312, proto: TCP (6), length: 57972)
06:37:41.575678 IP (id 14317, proto: TCP (6), length: 7292)
06:37:41.575683 IP (id 14361, proto: TCP (6), length: 63764)

It appears I introduced this bug in linux-3.1.

inet_getid() must return the old value of peer->ip_id_count,
not the new one.

Lets revert this part, and remove the prevention of
a null identification field in IPv6 Fragment Extension Header,
which is dubious and not even done properly.

Fixes: 87c48fa3b463 ("ipv6: make fragment identifications less predictable")
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: tunnels - enable module autoloading

2014-06-26T19:12:38+00:00

[ Upstream commit f98f89a0104454f35a62d681683c844f6dbf4043 ]

Enable the module alias hookup to allow tunnel modules to be autoloaded on demand.

This is in line with how most other netdev kinds work, and will allow userspace
to create tunnels without having CAP_SYS_MODULE.

Signed-off-by: Tom Gundersen 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

netfilter: Fix potential use after free in ip6_route_me_harder()

2014-06-11T19:03:27+00:00

commit a8951d5814e1373807a94f79f7ccec7041325470 upstream.

Dst is released one line before we access it again with dst->error.

Fixes: 58e35d147128 netfilter: ipv6: propagate routing errors from
ip6_route_me_harder()

Signed-off-by: Sergey Popovich 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Greg Kroah-Hartman

ip6_tunnel: fix potential NULL pointer dereference

2014-05-31T04:52:16+00:00

[ Upstream commit c8965932a2e3b70197ec02c6741c29460279e2a8 ]

The function ip6_tnl_validate assumes that the rtnl
attribute IFLA_IPTUN_PROTO always be filled . If this
attribute is not filled by  the userspace application
kernel get crashed with NULL pointer dereference. This
patch fixes the potential kernel crash when
IFLA_IPTUN_PROTO is missing .

Signed-off-by: Susant Sahani 
Acked-by: Thomas Graf 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: ipv6: send pkttoobig immediately if orig frag size > mtu

2014-05-31T04:52:16+00:00

[ Upstream commit 418a31561d594a2b636c1e2fa94ecd9e1245abb1 ]

If conntrack defragments incoming ipv6 frags it stores largest original
frag size in ip6cb and sets ->local_df.

We must thus first test the largest original frag size vs. mtu, and not
vice versa.

Without this patch PKTTOOBIG is still generated in ip6_fragment() later
in the stack, but

1) IPSTATS_MIB_INTOOBIGERRORS won't increment
2) packet did (needlessly) traverse netfilter postrouting hook.

Fixes: fe6cc55f3a9 ("net: ip, ipv6: handle gso skbs in forwarding path")
Signed-off-by: Florian Westphal 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv6: fib: fix fib dump restart

2014-05-31T04:52:15+00:00

[ Upstream commit 1c2658545816088477e91860c3a645053719cb54 ]

When the ipv6 fib changes during a table dump, the walk is
restarted and the number of nodes dumped are skipped. But the existing
code doesn't advance to the next node after a node is skipped. This can
cause the dump to loop or produce lots of duplicates when the fib
is modified during the dump.

This change advances the walk to the next node if the current node is
skipped after a restart.

Signed-off-by: Kumar Sundararajan 
Signed-off-by: Chris Mason 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ip6_gre: don't allow to remove the fb_tunnel_dev

2014-05-31T04:52:15+00:00

[ Upstream commit 54d63f787b652755e66eb4dd8892ee6d3f5197fc ]

It's possible to remove the FB tunnel with the command 'ip link del ip6gre0' but
this is unsafe, the module always supposes that this device exists. For example,
ip6gre_tunnel_lookup() may use it unconditionally.

Let's add a rtnl handler for dellink, which will never remove the FB tunnel (we
let ip6gre_destroy_tunnels() do the job).

Introduced by commit c12b395a4664 ("gre: Support GRE over IPv6").

CC: Dmitry Kozlov 
Signed-off-by: Nicolas Dichtel 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman