Eric Dumazet 04ca6973f7 ip: make IP identifiers less predictable ... 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 73f156a6e8 ("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 <edumazet@google.com> Reported-by: Jeffrey Knockel <jeffk@cs.unm.edu> Reported-by: Jedidiah R. Crandall <crandall@cs.unm.edu> Cc: Willy Tarreau <w@1wt.eu> Cc: Hannes Frederic Sowa <hannes@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2014-07-28 18:46:34 -07:00
..
9p	9pnet: p9_client->conn field is unused. Remove it.	2014-03-25 16:38:16 -05:00
bluetooth	Bluetooth: Clearly distinguish mgmt LTK type from authenticated property	2014-05-23 11:24:04 -07:00
caif
irda	include/net/: Fix FSF address in file headers	2013-12-06 12:37:56 -05:00
iucv
netfilter	netfilter: nf_tables: 64bit stats need some extra synchronization	2014-07-14 12:00:17 +02:00
netns	Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf	2014-07-16 15:27:16 -07:00
nfc	NFC: Add RAW socket type support for SOCKPROTO_RAW	2014-05-20 00:06:04 +02:00
phonet
sctp	net: sctp: migrate most recently used transport to ktime	2014-06-11 12:23:17 -07:00
tc_act	net_sched: act: hide struct tcf_common from API	2014-02-12 19:23:32 -05:00
6lowpan.h	6lowpan: include net/net_namespace.h on 6lowpan namepsace header	2014-04-20 18:18:55 -04:00
act_api.h	net_sched: act: refuse to remove bound action outside	2014-02-12 19:23:32 -05:00
addrconf.h	net: ipv6: Introduce ip6_sk_dst_hoplimit.	2014-04-30 13:31:26 -04:00
af_ieee802154.h	ieee802154: add dgram sockopts for security control	2014-05-16 17:23:41 -04:00
af_rxrpc.h
af_unix.h
af_vsock.h	vsock: Make transport the proto owner	2014-05-05 13:13:50 -04:00
ah.h
arp.h	arp: make arp_invalidate static	2013-12-28 17:02:46 -05:00
atmclip.h
ax25.h
ax88796.h
busy_poll.h	sched, net: Fixup busy_loop_us_clock()	2014-01-13 17:39:11 +01:00
cfg80211-wext.h
cfg80211.h	Merge git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next	2014-05-22 13:58:36 -04:00
checksum.h	net: Allow csum_add to be provided in arch	2014-05-05 15:26:29 -04:00
cipso_ipv4.h	cipso: cleanup cipso_v4_translate() when !CONFIG_NETLABEL	2013-12-10 17:56:54 -05:00
cls_cgroup.h	cgroup: clean up cgroup_subsys names and initialization	2014-02-08 10:36:58 -05:00
codel.h	net: introduce reciprocal_scale helper and convert users	2014-01-21 23:17:20 -08:00
compat.h
datalink.h	net: Move prototype declaration to header file include/net/datalink.h from net/ipx/af_ipx.c	2014-02-09 17:32:50 -08:00
dcbevent.h	include/net/: Fix FSF address in file headers	2013-12-06 12:37:56 -05:00
dcbnl.h	include/net/: Fix FSF address in file headers	2013-12-06 12:37:56 -05:00
dn_dev.h	dn_dev: add support for IFA_FLAGS nl attribute	2013-12-10 21:50:00 -05:00
dn_fib.h
dn_neigh.h
dn_nsp.h
dn_route.h	net: Move prototype declaration to appropriate header file from decnet/af_decnet.c	2014-02-09 17:32:49 -08:00
dn.h	net: Move prototype declaration to header file include/net/dn.h from net/decnet/af_decnet.c	2014-02-09 17:32:49 -08:00
dsa.h	net: dsa: add ds_to_priv	2014-04-30 13:31:25 -04:00
dsfield.h
dst_ops.h
dst.h	ipv4: add a sock pointer to dst->output() path.	2014-04-15 13:47:15 -04:00
esp.h	net: move pskb_put() to core code	2013-11-07 19:28:58 -05:00
ethoc.h	net: ethoc: set up MII management bus clock	2014-02-04 20:19:51 -08:00
fib_rules.h
firewire.h
flow_keys.h
flow.h	ipv4, fib: pass LOOPBACK_IFINDEX instead of 0 to flowi4_iif	2014-04-16 15:05:11 -04:00
flowcache.h	flowcache: Make flow cache name space aware	2014-02-12 07:02:11 +01:00
garp.h
gen_stats.h
genetlink.h	genl: Add genlmsg_new_unicast() for unicast message allocation	2014-01-06 15:51:53 -08:00
gre.h	gre: Call gso_make_checksum	2014-06-04 22:46:38 -07:00
gro_cells.h
icmp.h
ieee80211_radiotap.h	mac80211: propagate STBC / LDPC flags to radiotap	2014-02-06 09:34:58 +01:00
ieee802154_netdev.h	ieee802154, mac802154: implement devkey record option	2014-05-16 17:23:42 -04:00
ieee802154.h	ieee802154: add definitions for link-layer security and header functions	2014-05-15 15:51:42 -04:00
if_inet6.h	ipv6: move DAD and addrconf_verify processing to workqueue	2014-03-28 16:54:50 -04:00
inet6_connection_sock.h	ipv4: add a sock pointer to ip_queue_xmit()	2014-04-15 12:58:34 -04:00
inet6_hashtables.h	ipv6: split inet6_ehashfn to hash functions per compilation unit	2013-10-19 19:45:34 -04:00
inet_common.h
inet_connection_sock.h	ipv4: add a sock pointer to ip_queue_xmit()	2014-04-15 12:58:34 -04:00
inet_ecn.h	tunnel: fix RFC number in comment for INET_ECN_decapsulate()	2014-05-07 15:30:52 -04:00
inet_frag.h	inet: remove old fragmentation hash initializing	2013-10-23 17:01:41 -04:00
inet_hashtables.h	net: Use a more standard macro for INET_ADDR_COOKIE	2014-05-14 16:07:23 -04:00
inet_sock.h	net: support marking accepting TCP sockets	2014-05-13 18:35:09 -04:00
inet_timewait_sock.h	ipv6: tcp: fix flowlabel value in ACK messages send from TIME_WAIT	2014-01-17 17:56:33 -08:00
inetpeer.h	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2014-06-03 23:32:12 -07:00
ip6_checksum.h	udp: Generic functions to set checksum	2014-06-04 22:46:38 -07:00
ip6_fib.h	ipv6: do not overwrite inetpeer metrics prematurely	2014-03-27 15:09:07 -04:00
ip6_route.h	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2014-05-24 00:32:30 -04:00
ip6_tunnel.h	net: unify the pcpu_tstats and br_cpu_netstats as one	2014-01-04 20:10:24 -05:00
ip_fib.h
ip_tunnels.h	ipv4: add a sock pointer to dst->output() path.	2014-04-15 13:47:15 -04:00
ip_vs.h	arch: Mass conversion of smp_mb__*()	2014-04-18 14:20:48 +02:00
ip.h	ip: make IP identifiers less predictable	2014-07-28 18:46:34 -07:00
ipcomp.h
ipconfig.h
ipv6.h	inetpeer: get rid of ip_id_count	2014-06-02 11:00:41 -07:00
ipx.h	net: Move prototype declaration to header file include/net/ipx.h from net/ipx/af_ipx.c	2014-02-09 17:32:50 -08:00
iw_handler.h
lapb.h
lib80211.h
llc_c_ac.h
llc_c_ev.h
llc_c_st.h
llc_conn.h
llc_if.h
llc_pdu.h	net: llc: fix order of evaluation in llc_conn_ac_inc_vr_by_1	2014-01-01 22:22:43 -05:00
llc_s_ac.h
llc_s_ev.h
llc_s_st.h
llc_sap.h
llc.h	llc: make lock static	2014-01-03 20:56:48 -05:00
mac80211.h	mac80211: add a single-transaction driver op to switch contexts	2014-05-26 11:04:41 +02:00
mac802154.h	ieee802154: add header structs with endiannes and operations	2014-03-14 22:15:26 -04:00
mip6.h	include/net/: Fix FSF address in file headers	2013-12-06 12:37:56 -05:00
mld.h
mrp.h
ndisc.h
neighbour.h	neigh: sysctl - simplify address calculation of gc_* variables	2014-07-14 14:32:51 -07:00
net_namespace.h	6lowpan: nuke net_ieee802154_lowpan() accessor when 6lowpan is disabled	2014-04-24 12:36:00 -04:00
net_ratelimit.h
netdma.h
netevent.h
netlabel.h	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next	2014-01-25 11:17:34 -08:00
netlink.h
netprio_cgroup.h	cgroup: clean up cgroup_subsys names and initialization	2014-02-08 10:36:58 -05:00
netrom.h
nexthop.h
nl802154.h	ieee802154: use ieee802154_addr instead of *_sa variants	2014-03-14 22:15:26 -04:00
p8022.h
ping.h	ipv6: make IPV6_RECVPKTINFO work for ipv4 datagrams	2014-01-19 19:53:18 -08:00
pkt_cls.h	sched, cls: check if we could overwrite actions when changing a filter	2014-04-27 23:42:39 -04:00
pkt_sched.h	net_sched: drr: warn when qdisc is not work conserving	2014-06-11 15:50:59 -07:00
protocol.h	net: Eliminate no_check from protosw	2014-05-23 16:28:53 -04:00
psnap.h
raw.h
rawv6.h
red.h	reciprocal_divide: update/correction of the algorithm	2014-01-21 23:17:20 -08:00
regulatory.h	cfg80211: Enable GO operation on additional channels	2014-04-09 10:55:34 +02:00
request_sock.h	inet: includes a sock_common in request_sock	2013-10-10 00:08:07 -04:00
rose.h
route.h	ipv4: remove ip_rt_dump from route.c	2014-03-24 12:45:01 -04:00
rtnetlink.h	rtnl: make ifla_policy static	2014-02-18 18:15:42 -05:00
sch_generic.h	sched, cls: check if we could overwrite actions when changing a filter	2014-04-27 23:42:39 -04:00
scm.h
secure_seq.h	inetpeer: get rid of ip_id_count	2014-06-02 11:00:41 -07:00
slhc_vj.h
snmp.h	net: clean up snmp stats code	2014-05-07 16:06:05 -04:00
sock.h	net: fix sparse warning in sk_dst_set()	2014-07-02 17:03:06 -07:00
Space.h	drivers: net: Include new header file in sbni.c	2013-12-19 18:51:20 -05:00
stp.h
tcp_memcontrol.h	tcp_memcontrol: Kill struct tcp_memcontrol	2013-10-21 18:43:02 -04:00
tcp_states.h
tcp.h	tcp: add gfp parameter to tcp_fragment	2014-06-10 22:30:58 -07:00
timewait_sock.h
transp_v6.h	ipv6: make IPV6_RECVPKTINFO work for ipv4 datagrams	2014-01-19 19:53:18 -08:00
tso.h	net: Add a software TSO helper API	2014-05-22 14:57:15 -04:00
udp.h	udp: call __skb_checksum_complete when doing full checksum	2014-06-15 01:00:49 -07:00
udplite.h
vsock_addr.h
vxlan.h	vxlan: Add support for UDP checksums (v4 sending, v6 zero csums)	2014-06-04 22:46:39 -07:00
wext.h
wimax.h	wimax: Spelling s/than/that/, wording s/destinatary/recipient/	2014-05-05 15:37:55 +02:00
wpan-phy.h	ieee802154: add netlink APIs for smartMAC configuration	2014-02-17 16:42:39 -05:00
x25.h
x25device.h
xfrm.h	xfrm: Remove useless xfrm_audit struct.	2014-04-23 08:21:04 +02:00