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FILS: Add DHss into FILS-Key-Data derivation when using FILS SK+PFS

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This part is missing from IEEE Std 802.11ai-2016, but the lack of DHss
here means there would not be proper PFS for the case where PMKSA
caching is used with FILS SK+PFS authentication. This was not really the
intent of the FILS design and that issue was fixed during REVmd work
with the changes proposed in
https://mentor.ieee.org/802.11/dcn/17/11-17-0906-04-000m-fils-fixes.docx
that add DHss into FILS-Key-Data (and PTK, in practice) derivation for
the PMKSA caching case so that a unique ICK, KEK, and TK are derived
even when using the same PMK.

Note: This is not backwards compatible, i.e., this breaks PMKSA caching
with FILS SK+PFS if only STA or AP side implementation is updated.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
This commit is contained in:
Jouni Malinen 2017-09-13 21:36:05 +03:00 • committed by Jouni Malinen
parent 41b8191485
commit 4cada9dcc1
7 changed files with 62 additions and 18 deletions
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15
src/rsn_supp/wpa.c
View file

@ -3639,8 +3639,12 @@ int fils_process_auth(struct wpa_sm *sm, const u8 *bssid, const u8 *data,
dh_ss ? wpabuf_len(dh_ss) : 0,
sm->pmk, &sm->pmk_len);
os_memset(rmsk, 0, sizeof(rmsk));
/* Don't use DHss in PTK derivation if PMKSA caching is not
* used. */
wpabuf_clear_free(dh_ss);
dh_ss = NULL;
if (res)
goto fail;
@ -3665,12 +3669,19 @@ int fils_process_auth(struct wpa_sm *sm, const u8 *bssid, const u8 *data,
}
if (fils_pmk_to_ptk(sm->pmk, sm->pmk_len, sm->own_addr, sm->bssid,
sm->fils_nonce, sm->fils_anonce, &sm->ptk,
ick, &ick_len, sm->key_mgmt, sm->pairwise_cipher,
sm->fils_nonce, sm->fils_anonce,
dh_ss ? wpabuf_head(dh_ss) : NULL,
dh_ss ? wpabuf_len(dh_ss) : 0,
&sm->ptk, ick, &ick_len,
sm->key_mgmt, sm->pairwise_cipher,
sm->fils_ft, &sm->fils_ft_len) < 0) {
wpa_printf(MSG_DEBUG, "FILS: Failed to derive PTK");
goto fail;
}
wpabuf_clear_free(dh_ss);
dh_ss = NULL;
sm->ptk_set = 1;
sm->tptk_set = 0;
os_memset(&sm->tptk, 0, sizeof(sm->tptk));