On Sun, 2019-02-10 at 22:06 +0100, Alexander Wetzel wrote:
>
> - Enforce cipher does not change when replacing a key.
is that actually required somehow?
> + * @EXT_SET_KEY: a new key must be set but is only valid for decryption
> + * @EXT_KEY_RX_TX: a key installed with @EXT_SET_KEY is becoming the
> + * designated Rx/Tx key for the station
Not sure I like the EXT_SET_KEY. There's also no "designated Rx key", is
there? It's always selected by key ID.
How about SET_KEY_RXONLY and SET_KEY_TX or something like that?
> +static int ieee80211_set_tx_key(struct ieee80211_sub_if_data *sdata,
> + const u8 *mac_addr, u8 key_idx)
> +{
> + struct ieee80211_local *local = sdata->local;
> + struct ieee80211_key *key;
> + struct sta_info *sta;
> + int ret;
> +
> + if (!wiphy_ext_feature_isset(local->hw.wiphy,
> + NL80211_EXT_FEATURE_EXT_KEY_ID))
> + return -EINVAL;
You set this, wouldn't it make more sense to check EXT_KEY_ID_NATIVE?
Or maybe this is because of the next patch?
> + sta = sta_info_get_bss(sdata, mac_addr);
> +
> + if (!sta)
> + return -EINVAL;
> +
> + if (sta->ptk_idx == key_idx)
> + return 0;
> +
> + mutex_lock(&local->key_mtx);
> + key = key_mtx_dereference(local, sta->ptk[key_idx]);
> +
> + if (key && key->flags & KEY_FLAG_RX_ONLY)
do you even need the flag? Isn't it equivalent to checking
sta->ptk_idx != key->idx
or so?
Less data to maintain would be better.
> + bool ext_native = ieee80211_hw_check(&local->hw, EXT_KEY_ID_NATIVE);
you sort of only need this in the next patch, but I guess it doesn't
matter that much
> +int ieee80211_key_activate_tx(struct ieee80211_key *key)
> +{
> + struct ieee80211_sub_if_data *sdata = key->sdata;
> + struct sta_info *sta = key->sta;
> + struct ieee80211_local *local = key->local;
> + struct ieee80211_key *old;
> + int ret;
> +
> + assert_key_lock(local);
> +
> + key->flags &= ~KEY_FLAG_RX_ONLY;
> +
> + if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) ||
> + key->conf.flags & (IEEE80211_KEY_FLAG_GENERATE_MMIC |
> + IEEE80211_KEY_FLAG_PUT_MIC_SPACE |
> + IEEE80211_KEY_FLAG_RESERVE_TAILROOM))
> + increment_tailroom_need_count(sdata);
> +
> + if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
> + ret = drv_set_key(local, EXT_KEY_RX_TX, sdata,
> + &sta->sta, &key->conf);
> + if (ret) {
> + sdata_err(sdata,
> + "failed to activate key for Tx (%d, %pM)\n",
> + key->conf.keyidx, sta->sta.addr);
> + return ret;
You've already cleared the RX_ONLY flag, which gets you inconsistent
data now.
> + }
> + }
> +
> + old = key_mtx_dereference(local, sta->ptk[sta->ptk_idx]);
> + sta->ptk_idx = key->conf.keyidx;
but you set this only here.
> - /* Stop TX till we are on the new key */
> + /* Stop Tx till we are on the new key */
Uh, I had to read that three times ... please don't make changes like
that? :)
> old_key->flags |= KEY_FLAG_TAINTED;
> ieee80211_clear_fast_xmit(sta);
>
> - /* Aggregation sessions during rekey are complicated due to the
> + /* Aggregation sessions during rekey are complicated by the
similarly here, please don't make drive-by comment wording issues (also,
I'm not sure I agree - the old version just treats "complicated" as an
adjective, you treat it as a verb, but ultimately doesn't really matter?
> #define NUM_DEFAULT_KEYS 4
> #define NUM_DEFAULT_MGMT_KEYS 2
> +#define INVALID_PTK_KEYIDX 2 /* Existing key slot never used by PTK keys */
We could also use something obviously wrong like 0xff?
> +++ b/net/mac80211/tx.c
> @@ -3000,23 +3000,15 @@ void ieee80211_check_fast_xmit(struct sta_info *sta)
> switch (build.key->conf.cipher) {
> case WLAN_CIPHER_SUITE_CCMP:
> case WLAN_CIPHER_SUITE_CCMP_256:
> - /* add fixed key ID */
> - if (gen_iv) {
> - (build.hdr + build.hdr_len)[3] =
> - 0x20 | (build.key->conf.keyidx << 6);
> + if (gen_iv)
> build.pn_offs = build.hdr_len;
> - }
> if (gen_iv || iv_spc)
> build.hdr_len += IEEE80211_CCMP_HDR_LEN;
> break;
> case WLAN_CIPHER_SUITE_GCMP:
> case WLAN_CIPHER_SUITE_GCMP_256:
> - /* add fixed key ID */
> - if (gen_iv) {
> - (build.hdr + build.hdr_len)[3] =
> - 0x20 | (build.key->conf.keyidx << 6);
> + if (gen_iv)
> build.pn_offs = build.hdr_len;
> - }
> if (gen_iv || iv_spc)
> build.hdr_len += IEEE80211_GCMP_HDR_LEN;
> break;
> @@ -3383,6 +3375,7 @@ static void ieee80211_xmit_fast_finish(struct
> ieee80211_sub_if_data *sdata,
> pn = atomic64_inc_return(&key->conf.tx_pn);
> crypto_hdr[0] = pn;
> crypto_hdr[1] = pn >> 8;
> + crypto_hdr[3] = 0x20 | (key->conf.keyidx << 6);
> crypto_hdr[4] = pn >> 16;
> crypto_hdr[5] = pn >> 24;
> crypto_hdr[6] = pn >> 32;
This shouldn't be needed, you do update the fast TX cache when changing
the key?
johannes
