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2016-12-02tcp: allow to turn tcp timestamp randomization offFlorian Westphal1-2/+3
Eric says: "By looking at tcpdump, and TS val of xmit packets of multiple flows, we can deduct the relative qdisc delays (think of fq pacing). This should work even if we have one flow per remote peer." Having random per flow (or host) offsets doesn't allow that anymore so add a way to turn this off. Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Florian Westphal <fw@strlen.de> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-02tcp: randomize tcp timestamp offsets for each connectionFlorian Westphal1-4/+6
jiffies based timestamps allow for easy inference of number of devices behind NAT translators and also makes tracking of hosts simpler. commit ceaa1fef65a7c2e ("tcp: adding a per-socket timestamp offset") added the main infrastructure that is needed for per-connection ts randomization, in particular writing/reading the on-wire tcp header format takes the offset into account so rest of stack can use normal tcp_time_stamp (jiffies). So only two items are left: - add a tsoffset for request sockets - extend the tcp isn generator to also return another 32bit number in addition to the ISN. Re-use of ISN generator also means timestamps are still monotonically increasing for same connection quadruple, i.e. PAWS will still work. Includes fixes from Eric Dumazet. Signed-off-by: Florian Westphal <fw@strlen.de> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-25net: remove a sparse error in secure_dccpv6_sequence_number()Eric Dumazet1-1/+1
make C=2 CF=-D__CHECK_ENDIAN__ net/core/secure_seq.o net/core/secure_seq.c:157:50: warning: restricted __be32 degrades to integer Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-22net: use ktime_get_ns() and ktime_get_real_ns() helpersEric Dumazet1-3/+3
ktime_get_ns() replaces ktime_to_ns(ktime_get()) ktime_get_real_ns() replaces ktime_to_ns(ktime_get_real()) Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-02inetpeer: get rid of ip_id_countEric Dumazet1-25/+0
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 <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-23Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-0/+2
Conflicts: drivers/net/usb/qmi_wwan.c include/net/dst.h Trivial merge conflicts, both were overlapping changes. Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-23net: always inline net_secret_initHannes Frederic Sowa1-1/+1
Currently net_secret_init does not get inlined, so we always have a call to net_secret_init even in the fast path. Let's specify net_secret_init as __always_inline so we have the nop in the fast-path without the call to net_secret_init and the unlikely path at the epilogue of the function. jump_labels handle the inlining correctly. Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-19net: switch net_secret key generation to net_get_random_onceHannes Frederic Sowa1-12/+2
Cc: Eric Dumazet <edumazet@google.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-09net: secure_seq: Fix warning when CONFIG_IPV6 and CONFIG_INET are not selectedFabio Estevam1-0/+2
net_secret() is only used when CONFIG_IPV6 or CONFIG_INET are selected. Building a defconfig with both of these symbols unselected (Using the ARM at91sam9rl_defconfig, for example) leads to the following build warning: $ make at91sam9rl_defconfig # # configuration written to .config # $ make net/core/secure_seq.o scripts/kconfig/conf --silentoldconfig Kconfig CHK include/config/kernel.release CHK include/generated/uapi/linux/version.h CHK include/generated/utsrelease.h make[1]: `include/generated/mach-types.h' is up to date. CALL scripts/checksyscalls.sh CC net/core/secure_seq.o net/core/secure_seq.c:17:13: warning: 'net_secret_init' defined but not used [-Wunused-function] Fix this warning by protecting the definition of net_secret() with these symbols. Reported-by: Olof Johansson <olof@lixom.net> Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-09-28net: net_secret should not depend on TCPEric Dumazet1-3/+24
A host might need net_secret[] and never open a single socket. Problem added in commit aebda156a570782 ("net: defer net_secret[] initialization") Based on prior patch from Hannes Frederic Sowa. Reported-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Hannes Frederic Sowa <hannes@strressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-04-29net: defer net_secret[] initializationEric Dumazet1-3/+1
Instead of feeding net_secret[] at boot time, defer the init at the point first socket is created. This permits some platforms to use better entropy sources than the ones available at boot time. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2012-08-30netfilter: ipv6: add IPv6 NAT supportPatrick McHardy1-0/+1
Signed-off-by: Patrick McHardy <kaber@trash.net>
2012-01-17net: fix some sparse errorsEric Dumazet1-1/+1
make C=2 CF="-D__CHECK_ENDIAN__" M=net And fix flowi4_init_output() prototype for sport Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2011-12-16net:core: use IS_ENABLEDIgor Maravić1-1/+1
Use IS_ENABLED(CONFIG_FOO) instead of defined(CONFIG_FOO) || defined (CONFIG_FOO_MODULE) Signed-off-by: Igor Maravić <igorm@etf.rs> Signed-off-by: David S. Miller <davem@davemloft.net>
2011-12-11net: use IS_ENABLED(CONFIG_IPV6)Eric Dumazet1-2/+2
Instead of testing defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2011-12-06net: Silence seq_scale() unused warningStephen Boyd1-0/+2
On a CONFIG_NET=y build net/core/secure_seq.c:22: warning: 'seq_scale' defined but not used Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2011-10-21tcp: add const qualifiers where possibleEric Dumazet1-1/+1
Adding const qualifiers to pointers can ease code review, and spot some bugs. It might allow compiler to optimize code further. For example, is it legal to temporary write a null cksum into tcphdr in tcp_md5_hash_header() ? I am afraid a sniffer could catch the temporary null value... Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2011-08-06net: Compute protocol sequence numbers and fragment IDs using MD5.David S. Miller1-0/+184
Computers have become a lot faster since we compromised on the partial MD4 hash which we use currently for performance reasons. MD5 is a much safer choice, and is inline with both RFC1948 and other ISS generators (OpenBSD, Solaris, etc.) Furthermore, only having 24-bits of the sequence number be truly unpredictable is a very serious limitation. So the periodic regeneration and 8-bit counter have been removed. We compute and use a full 32-bit sequence number. For ipv6, DCCP was found to use a 32-bit truncated initial sequence number (it needs 43-bits) and that is fixed here as well. Reported-by: Dan Kaminsky <dan@doxpara.com> Tested-by: Willy Tarreau <w@1wt.eu> Signed-off-by: David S. Miller <davem@davemloft.net>
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