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If asynchronous events are enabled for a particular netlink socket,
the notify function is called by the advance function. The notify
function creates and dispatches a km_event if a replay timeout occurred,
or at least replay_maxdiff packets have been received since the last
asynchronous event has been sent. The function is supposed to return if
neither of the two events were detected for a state, or replay_maxdiff
is equal to zero.
Replay_maxdiff is initialized in xfrm_state_construct to the value of
the xfrm.sysctl_aevent_rseqth (2 by default), and updated if for a state
if the netlink attribute XFRMA_REPLAY_THRESH is set.
If, however, replay_maxdiff is set to zero, then all of the three notify
implementations perform a break from the switch statement instead of
checking whether a timeout occurred, and -- if not -- return. As a
result an asynchronous event is generated for every replay update of a
state that has a zero replay_maxdiff value.
This patch modifies the notify functions such that they immediately
return if replay_maxdiff has the value zero, unless a timeout occurred.
Signed-off-by: Thomas Egerer <thomas.egerer@secunet.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
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For legacy IPsec anti replay mechanism:
bitmap in struct xfrm_replay_state could only provide a 32 bits
window size limit in current design, thus user level parameter
sadb_sa_replay should honor this limit, otherwise misleading
outputs("replay=244") by setkey -D will be:
192.168.25.2 192.168.22.2
esp mode=transport spi=147561170(0x08cb9ad2) reqid=0(0x00000000)
E: aes-cbc 9a8d7468 7655cf0b 719d27be b0ddaac2
A: hmac-sha1 2d2115c2 ebf7c126 1c54f186 3b139b58 264a7331
seq=0x00000000 replay=244 flags=0x00000000 state=mature
created: Sep 17 14:00:00 2013 current: Sep 17 14:00:22 2013
diff: 22(s) hard: 30(s) soft: 26(s)
last: Sep 17 14:00:00 2013 hard: 0(s) soft: 0(s)
current: 1408(bytes) hard: 0(bytes) soft: 0(bytes)
allocated: 22 hard: 0 soft: 0
sadb_seq=1 pid=4854 refcnt=0
192.168.22.2 192.168.25.2
esp mode=transport spi=255302123(0x0f3799eb) reqid=0(0x00000000)
E: aes-cbc 6485d990 f61a6bd5 e5660252 608ad282
A: hmac-sha1 0cca811a eb4fa893 c47ae56c 98f6e413 87379a88
seq=0x00000000 replay=244 flags=0x00000000 state=mature
created: Sep 17 14:00:00 2013 current: Sep 17 14:00:22 2013
diff: 22(s) hard: 30(s) soft: 26(s)
last: Sep 17 14:00:00 2013 hard: 0(s) soft: 0(s)
current: 1408(bytes) hard: 0(bytes) soft: 0(bytes)
allocated: 22 hard: 0 soft: 0
sadb_seq=0 pid=4854 refcnt=0
And also, optimizing xfrm_replay_check window checking by setting the
desirable x->props.replay_window with only doing the comparison once
for all when xfrm_state is first born.
Signed-off-by: Fan Du <fan.du@windriver.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
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Commit 0017c0b "xfrm: Fix replay notification for esn." is off by one
for the sequence number wrapped case as UINT_MAX is 0xffffffff, not
0x100000000. ;)
Just calculate the diff like done everywhere else in the file.
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
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We may miscalculate the sequence number difference from the
last time we send a notification if a sequence number wrap
occured in the meantime. We fix this by adding a separate
replay notify function for esn. Here we take the high bits
of the sequence number into account to calculate the
difference.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
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All of the xfrm_replay->advance functions in xfrm_replay.c check if
x->replay_esn->replay_window is zero (and return if so). However,
one of them, xfrm_replay_advance_bmp(), divides by that value (in the
'%' operator) before doing the check, which can potentially trigger
a divide-by-zero exception. Some compilers will also assume that the
earlier division means the value cannot be zero later, and thus will
eliminate the subsequent zero check as dead code.
This patch moves the division to after the check.
Signed-off-by: Nickolai Zeldovich <nickolai@csail.mit.edu>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
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x->replay_esn is already checked in if clause,
so remove check and ident properly
Signed-off-by: Ulrich Weber <ulrich.weber@sophos.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
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ESN for esp is defined in RFC 4303. This RFC assumes that the
sequence number counters are always up to date. However,
this is not true if an async crypto algorithm is employed.
If the sequence number counters are not up to date on sequence
number check, we may incorrectly update the upper 32 bit of
the sequence number. This leads to a DOS.
We workaround this by comparing the upper sequence number,
(used for authentication) with the upper sequence number
computed after the async processing. We drop the packet
if these numbers are different.
To do this, we introduce a recheck function that does this
check in the ESN case.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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We call the wrong replay notify function when we use ESN replay
handling. This leads to the fact that we don't send notifications
if we use ESN. Fix this by calling the registered callbacks instead
of xfrm_replay_notify().
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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These files are non modular, but need to export symbols using
the macros now living in export.h -- call out the include so
that things won't break when we remove the implicit presence
of module.h from everywhere.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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The replay check and replay advance functions had some code
duplications. This patch removes the duplications.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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We may write 4 byte too much when we reinitialize the anti replay
window in the replay advance functions. This patch fixes this by
adjusting the last index of the initialization loop.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Unlike the standard case, disabled anti replay detection needs some
nontrivial extra treatment on ESN. RFC 4303 states:
Note: If a receiver chooses to not enable anti-replay for an SA, then
the receiver SHOULD NOT negotiate ESN in an SA management protocol.
Use of ESN creates a need for the receiver to manage the anti-replay
window (in order to determine the correct value for the high-order
bits of the ESN, which are employed in the ICV computation), which is
generally contrary to the notion of disabling anti-replay for an SA.
So return an error if an ESN state with disabled anti replay detection
is inserted for now and add the extra treatment later if we need it.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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On replay initialization, we compute the size of the replay
buffer to see if the replay window fits into the buffer.
This computation lacks a mutliplication by 8 because we need
the size in bit, not in byte. So we might return an error
even though the replay window would fit into the buffer.
This patch fixes this issue.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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As it is, the replay check is just performed if the replay window of the
legacy implementation is nonzero. So we move the test on a nonzero replay
window inside the replay check functions to be sure we are testing for the
right implementation.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This patch adds support for IPsec extended sequence numbers (esn)
as defined in RFC 4303. The bits to manage the anti-replay window
are based on a patch from Alex Badea.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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As it is, the anti-replay bitmap in struct xfrm_replay_state can
only accomodate 32 packets. Even though it is possible to configure
anti-replay window sizes up to 255 packets from userspace. So we
reject any packet with a sequence number within the configured window
but outside the bitmap. With this patch, we represent the anti-replay
window as a bitmap of variable length that can be accessed via the
new struct xfrm_replay_state_esn. Thus, we have no limit on the
window size anymore. To use the new anti-replay window implementantion,
new userspace tools are required. We leave the old implementation
untouched to stay in sync with old userspace tools.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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To support multiple versions of replay detection, we move the replay
detection functions to a separate file and make them accessible
via function pointers contained in the struct xfrm_replay.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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