mac80211: check PN correctly for GCMP-encrypted fragmented MPDUs

commit 9acc54beb474c81148e2946603d141cf8716b19f upstream.

Just like for CCMP we need to check that for GCMP the fragments
have PNs that increment by one; the spec was updated to fix this
security issue and now has the following text:

	The receiver shall discard MSDUs and MMPDUs whose constituent
	MPDU PN values are not incrementing in steps of 1.

Adapt the code for CCMP to work for GCMP as well, luckily the
relevant fields already alias each other so no code duplication
is needed (just check the aliasing with BUILD_BUG_ON.)

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 5322b4c716307f90710153bdb91e5425221b1742..6837a46ca4a2dd682a999d59ac0dab1aba5597db 100644 (file)
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -92,7 +92,7 @@ struct ieee80211_fragment_entry {
        u16 extra_len;
        u16 last_frag;
        u8 rx_queue;
-       bool ccmp; /* Whether fragments were encrypted with CCMP */
+       bool check_sequential_pn; /* needed for CCMP/GCMP */
        u8 last_pn[6]; /* PN of the last fragment if CCMP was used */
 };
 

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 82af407fea7a094db5f08e6426ae670a4cab3729..08063e105b1cf892dff7be4ffdbc5a04e9b2c1d4 100644 (file)
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -1754,7 +1754,7 @@ ieee80211_reassemble_add(struct ieee80211_sub_if_data *sdata,
        entry->seq = seq;
        entry->rx_queue = rx_queue;
        entry->last_frag = frag;
-       entry->ccmp = 0;
+       entry->check_sequential_pn = false;
        entry->extra_len = 0;
 
        return entry;
@@ -1850,15 +1850,27 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
                                                 rx->seqno_idx, &(rx->skb));
                if (rx->key &&
                    (rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP ||
-                    rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP_256) &&
+                    rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP_256 ||
+                    rx->key->conf.cipher == WLAN_CIPHER_SUITE_GCMP ||
+                    rx->key->conf.cipher == WLAN_CIPHER_SUITE_GCMP_256) &&
                    ieee80211_has_protected(fc)) {
                        int queue = rx->security_idx;
-                       /* Store CCMP PN so that we can verify that the next
-                        * fragment has a sequential PN value. */
-                       entry->ccmp = 1;
+
+                       /* Store CCMP/GCMP PN so that we can verify that the
+                        * next fragment has a sequential PN value.
+                        */
+                       entry->check_sequential_pn = true;
                        memcpy(entry->last_pn,
                               rx->key->u.ccmp.rx_pn[queue],
                               IEEE80211_CCMP_PN_LEN);
+                       BUILD_BUG_ON(offsetof(struct ieee80211_key,
+                                             u.ccmp.rx_pn) !=
+                                    offsetof(struct ieee80211_key,
+                                             u.gcmp.rx_pn));
+                       BUILD_BUG_ON(sizeof(rx->key->u.ccmp.rx_pn[queue]) !=
+                                    sizeof(rx->key->u.gcmp.rx_pn[queue]));
+                       BUILD_BUG_ON(IEEE80211_CCMP_PN_LEN !=
+                                    IEEE80211_GCMP_PN_LEN);
                }
                return RX_QUEUED;
        }
@@ -1873,15 +1885,21 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
                return RX_DROP_MONITOR;
        }
 
-       /* Verify that MPDUs within one MSDU have sequential PN values.
-        * (IEEE 802.11i, 8.3.3.4.5) */
-       if (entry->ccmp) {
+       /* "The receiver shall discard MSDUs and MMPDUs whose constituent
+        *  MPDU PN values are not incrementing in steps of 1."
+        * see IEEE P802.11-REVmc/D5.0, 12.5.3.4.4, item d (for CCMP)
+        * and IEEE P802.11-REVmc/D5.0, 12.5.5.4.4, item d (for GCMP)
+        */
+       if (entry->check_sequential_pn) {
                int i;
                u8 pn[IEEE80211_CCMP_PN_LEN], *rpn;
                int queue;
+
                if (!rx->key ||
                    (rx->key->conf.cipher != WLAN_CIPHER_SUITE_CCMP &&
-                    rx->key->conf.cipher != WLAN_CIPHER_SUITE_CCMP_256))
+                    rx->key->conf.cipher != WLAN_CIPHER_SUITE_CCMP_256 &&
+                    rx->key->conf.cipher != WLAN_CIPHER_SUITE_GCMP &&
+                    rx->key->conf.cipher != WLAN_CIPHER_SUITE_GCMP_256))
                        return RX_DROP_UNUSABLE;
                memcpy(pn, entry->last_pn, IEEE80211_CCMP_PN_LEN);
                for (i = IEEE80211_CCMP_PN_LEN - 1; i >= 0; i--) {