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Fix MM Auth: zero-initialize auth tuple before first use 

Make sure a new auth tuple is initialized after
db_get_lastauthtuple_for_subscr() returns an error, i.e. if no tuple is present
for the subscriber yet.

Before this patch, the first key_seq depended on the typically uninitialized
value that was present in auth tuple's key_seq upon calling
auth_get_tuple_for_subscr().

The very first key_seq used for a new subscriber will now always be 0. Before,
it used to be mostly 1 ("(0 + 1) % 7"), but depended on whether the key_seq was
indeed initialized with 0, actually by random.
This commit is contained in:
Neels Hofmeyr 2016-03-30 11:22:30 +02:00 committed by Harald Welte
parent 0d929be826
commit cf1302e4cb
3 changed files with 37 additions and 2 deletions
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11
openbsc/src/libmsc/auth.c
View File

@ -110,8 +110,17 @@ int auth_get_tuple_for_subscr(struct gsm_auth_tuple *atuple,
}
/* Generate a new one */
if (rc != 0) {
/* If db_get_lastauthtuple_for_subscr() returned nothing, make
* sure the atuple memory is initialized to zero and thus start
* off with key_seq = 0. */
memset(atuple, 0, sizeof(*atuple));
} else {
/* If db_get_lastauthtuple_for_subscr() returned a previous
* tuple, use the next key_seq. */
atuple->key_seq = (atuple->key_seq + 1) % 7;
}
atuple->use_count = 1;
atuple->key_seq = (atuple->key_seq + 1) % 7;
if (RAND_bytes(atuple->rand, sizeof(atuple->rand)) != 1) {
LOGP(DMM, LOGL_NOTICE, "RAND_bytes failed, can't generate new auth tuple\n");

24
openbsc/tests/mm_auth/mm_auth_test.c
View File

@ -183,7 +183,29 @@ static void test_auth_then_ciph1()
OSMO_ASSERT(auth_tuple_is(&atuple,
"gsm_auth_tuple {\n"
" .use_count = 1\n"
" .key_seq = 1\n"
" .key_seq = 0\n"
" .rand = 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 \n"
" .sres = a1 ab c6 90 \n"
" .kc = 0f 27 ed f3 ac 97 ac 00 \n"
"}\n"
));
/* With a different last saved key_seq stored in the out-arg of
* db_get_lastauthtuple_for_subscr() by coincidence, expect absolutely
* the same as above. */
test_auth_info = default_auth_info;
test_last_auth_tuple = default_auth_tuple;
test_last_auth_tuple.key_seq = 3;
test_get_authinfo_rc = 0;
test_get_lastauthtuple_rc = -ENOENT;
key_seq = 0;
auth_action = auth_get_tuple_for_subscr_verbose(&atuple, &subscr,
key_seq);
OSMO_ASSERT(auth_action == AUTH_DO_AUTH_THEN_CIPH);
OSMO_ASSERT(auth_tuple_is(&atuple,
"gsm_auth_tuple {\n"
" .use_count = 1\n"
" .key_seq = 0\n"
" .rand = 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 \n"
" .sres = a1 ab c6 90 \n"
" .kc = 0f 27 ed f3 ac 97 ac 00 \n"

4
openbsc/tests/mm_auth/mm_auth_test.ok
View File

@ -12,6 +12,10 @@ wrapped: db_get_authinfo_for_subscr(): rc = 0
wrapped: db_get_lastauthtuple_for_subscr(): rc = -2
wrapped: db_sync_lastauthtuple_for_subscr(): rc = 0
auth_get_tuple_for_subscr(key_seq=0) --> auth_action == AUTH_DO_AUTH_THEN_CIPH
wrapped: db_get_authinfo_for_subscr(): rc = 0
wrapped: db_get_lastauthtuple_for_subscr(): rc = -2
wrapped: db_sync_lastauthtuple_for_subscr(): rc = 0
auth_get_tuple_for_subscr(key_seq=0) --> auth_action == AUTH_DO_AUTH_THEN_CIPH
* test_auth_then_ciph2()
wrapped: db_get_authinfo_for_subscr(): rc = 0