We don't need to consume all the entropy of the kernel but can
use libcrypto (OpenSSL) to generate random data. It is not clear
if we need to call RAND_load_file but I think we can assume that
our Unices have a /dev/urandom.
This takes less CPU time, provides good enough entropy (in theory)
and leaves some in the kernel entropy pool.
We are using the token to find the right bsc_config and
then we can use the last_rand of the bsc_connection to
calculate the expected result and try to compare it with
a time constant(???) memcmp.
Check if the NAT has sent 16 bytes of RAND and if a key
has been configured in the system and then generate a
result using milenage. The milenage res will be sent and
noth the four byte GSM SRES derivation.
Generate 16 byte of random data to be used for A3A8 by
the BSC in the response. We can't know which BSC it is
at this point and I don't want to send another message
once the token has been received so always send the data
with an undefined code. The old BSCs don't parse the
message and will happily ignore the RAND.
/dev/urandom can give short reads on Linux so loop
around it until the bytes have been read from the kernel.
Instead of doing open/read/close all the time, open the
FD in the beginning and keep it open. To scare me even
more I have seen /dev/urandom actually providing a short
read and then blocking but it seems to be the best way
to get the random byes we need for authentication.
So one should/could run the cheap random generator on
the system (e.g. haveged) or deal with the NAT process
to block.
Unfortunately the basic structure of the response is broken.
There is a two byte length followed by data. The concept of
a 'tag' happens to be the first byte of the data.
This means we want to write strlen of the token, then we
want to write the NUL and then we need to account for the
tag in front.
Introduce a flag if the new or old format should be used.
This will allow to have new BSCs talk to old NATs without
an additional change. In the long run we can clean that up.
In case the token was not correct, just close the connection.
It is not clear that forcing a new TCP connection is going to
give us any extra security here. But with the upcoming auth
handling it does make sense to have both case look similar.
Move the filter methods to the filter module. This is
still only usable for the NAT and the _dt/_cr filter
routines need to move back to the bsc_nat in the long
run.
On DT messages we directly write into the tracked SCCP
connection. This means "imsi" will always be NULL at
this check. Change the code to use con->imsi
Fixes: Coverity CID 1293151
I used strdup in case the data would not be valid from after
the call to getopt and this creates a potential leak if a user
is specifying multiple configuration files. If I depend on the
fact that the string is a pointer into the argv[] array I can
kill the strdup and fix the unlikely leak.
Fixes: Coverity CID 1206578
The code in the BSC/NAT called ipaccess_rcvmsg_base without
checking if the protocol is IPA. This lead the BSC to respond
to SCCP messages with an "ID ACK". From a quick look neither
the code of ipaccess_rcvmsg_base in OpenBSC nor the copy of
libosmo-abis ever checked the protocol header. So this code
has been wrong since initially being created in 2010.
Coverity complains about checking connection->cfg in
bsc_close_connection() at one place but not at the second.
This patch fixes this by adding a check before accessing cfg when
generating the 'partial message' log message.
Fixes: Coverity CID 1195180
Sponsored-by: On-Waves ehf
The log message lacked a lot of context. A SCCP connection is
created on behalf of a configured BSC. This way we should be
able to always list this information.
The old ipa_msg_recv() implementation didn't support partial receive,
so IPA connections got disconnected when this happened.
This patch adds the handling of the temporary message buffers and uses
ipa_msg_recv_buffered().
It has been successfully tested by jerlbeck with osmo-nitb and
osmo-bsc.
Ticket: OW#768
Sponsored-by: On-Waves ehf
In case of the RLSD coming from the MSC we are patching the address
in-situ but for local calls set con = NULL. We then answered the RLSD
with the wrong reference and the MSC kept on trying.
Assign a static name to a MSC Connection and use it. In case there
are multiple connections we can now more easily identify them.
This is only used for the NAT right now, the BSC could start to
name the various MSC connections too.
* It is a trie. The max depth of the trie is the length of the
longest prefix. The lookup is O(lookuped_prefix), but as the prefix
length is limited, the lookup time is constant.
* Each node can hold the entire prefix, has place for the rewrite
rule with up to three digits.
* A trie with 20k entries will take about 3MB ram.
* Filling the trie 100 times takes ~800ms on my i7 laptop
* 10.000.000 lookups take 315ms.. (for the same prefix).
* 93/99 lines are tested, 6/6 functions are tested, 49 of 54 branches
are tested. Only memory allocation failures are not covered
* A late addition is to handle the '+' sign and to increase the number
of chars in the rewrite prefix. The timing/line coverage has not
been updated after this change.
Coverity pointed out that this code is logically dead. Quickly
judging the code we will forward the RSLD message anyway. Remove
the code for now and next time I work on the NAT/USSD bridge I
will have a look at the flow of the RLSD messages.
Fixes: Coverity CID 1042327
Find the Cell Identifier from the Complete Layer3 Information and
store it for future reference. We could begin to verify that the
LAC/CI used really belongs to the BSC.
The name sccp_connection is used in the osmo-sccp code, sccp_connections
was used in the NAT for tracking a sccp_connection. Rename it so it is
obvious that the struct belongs to the nat.
The rename was done with sed:
$ sed -i s,"struct sccp_connections","struct nat_sccp_connection",g \
include/openbsc/*.h src/osmo-bsc_nat/* tests/*/*
The token was compared with the configured one but only up to a
user supplied length. Compare the token sizes and then use memcmp
for the actual comparison to make sure to compare the right ammount
of characters.
There is no unit-test but there should be one.
For USSD we remember that it is a supplementary service but this
means we sent no CM Service Reject down to the subscriber. Treat
NAT_CON_TYPE_CM_SERV_REQ and NAT_CON_TYPE_SSA the same and send
a cm service reject.
In preparation for another kind of black-list allow the filter code
to decide how the connection should be rejected. Introduce a new struct
that will carry the reject causes for certain operations.
Move to the control command handling out of the main file into
a dedicated module. There are still some calls embedded into the
main code but it will be moved soon.
The commands net.<netid>.bsc.<bscid>.* are now forwarded to the
appropriate osmo-bsc. <netid> for now is just 0. <bscid> is not the LAC
anymore (since that could be ambiguous), but instead the number as
configured in bsc-nat.cfg
nat: Catch up with controlif_setup API change
We now save a control handle reference in the nat
osmo-bsc: Catch up with controlif_setup API change
We now save a control handle reference in the gsm network
This is a big patch that ports openBSC over libosmo-abis.
Sorry, the changes that are included here are all dependent
of libosmo-abis, splitting them into smaller pieces would
leave the repository in some intermediate state, which is
not desired.
The main changes are:
- The directory libabis/ has been removed as it now lives in
libosmo-abis.
- new configuration file format for nanoBTS and HSL femto, we
need to define the virtual e1_line and attach it to the OML
link.
- all the existing BTS drivers (nanoBTS, hsl femto, Nokia site,
BS11 and rbs2000) now use the new libosmo-abis framework.
- use r232 input driver available in libosmo-abis for bs11_config.
- use ipa_msg_recv instead of old ipaccess_read_msg function.
- delete definition of gsm_e1_subslot and input_signal_data.
These structures now lives in libosmo-abis.
Most of this patch are deletions of libabis/ which has been
moved to libosmo-abis.
This patch also modifies openBSC to use all the new definitions
available in libosmocore and libosmo-abis. In order to do that,
we have replaced the following:
- DINP, DMI, DMIB and DMUX by their respective DL* correspondences.
- SS_GLOBAL by SS_L_GLOBAL
- SS_INPUT by SS_L_INPUT
- S_GLOBAL_SHUTDOWN by S_L_GLOBAL_SHUTDOWN
- SS_INPUT by SS_L_INPUT
- S_INP_* by S_L_INP_* sub-signals
- E1INP_NODE by L_E1INP_NODE vty node
This patch has been tested with:
- one nanoBTS
- the HSL femto with the examples available under libosmo-abis
- BS11 with both dahdi and misdn drivers.
Holger Hans Peter Freyther
Harald Welte