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mac80211: IEEE 802.11 Extended Key ID support

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Add support for Extended Key ID as defined in IEEE 802.11-2016.

 - Implement the nl80211 API for Extended Key ID
 - Extend mac80211 API to allow drivers to support Extended Key ID
 - Enable Extended Key ID by default for drivers only supporting SW
   crypto (e.g. mac80211_hwsim)
 - Allow unicast Tx usage to be supressed (IEEE80211_KEY_FLAG_NO_AUTO_TX)
 - Select the decryption key based on the MPDU keyid
 - Enforce existing assumptions in the code that rekeys don't change the
   cipher

Signed-off-by: Alexander Wetzel <alexander@wetzel-home.de>
[remove module parameter]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Alexander Wetzel 2019-03-19 21:34:08 +01:00 committed by Johannes Berg
parent 6cdd3979a2
commit 96fc6efb9a
10 changed files with 151 additions and 60 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/net/mac80211.h
View File

@ -1697,6 +1697,7 @@ struct wireless_dev *ieee80211_vif_to_wdev(struct ieee80211_vif *vif);
* @IEEE80211_KEY_FLAG_PUT_MIC_SPACE: This flag should be set by the driver for
* a TKIP key if it only requires MIC space. Do not set together with
* @IEEE80211_KEY_FLAG_GENERATE_MMIC on the same key.
* @IEEE80211_KEY_FLAG_NO_AUTO_TX: Key needs explicit Tx activation.
*/
enum ieee80211_key_flags {
IEEE80211_KEY_FLAG_GENERATE_IV_MGMT = BIT(0),
@ -1708,6 +1709,7 @@ enum ieee80211_key_flags {
IEEE80211_KEY_FLAG_RX_MGMT = BIT(6),
IEEE80211_KEY_FLAG_RESERVE_TAILROOM = BIT(7),
IEEE80211_KEY_FLAG_PUT_MIC_SPACE = BIT(8),
IEEE80211_KEY_FLAG_NO_AUTO_TX = BIT(9),
};
/**
@ -2243,6 +2245,9 @@ struct ieee80211_txq {
* @IEEE80211_HW_SUPPORTS_ONLY_HE_MULTI_BSSID: Hardware supports multi BSSID
* only for HE APs. Applies if @IEEE80211_HW_SUPPORTS_MULTI_BSSID is set.
*
* @IEEE80211_HW_EXT_KEY_ID_NATIVE: Driver and hardware are supporting Extended
* Key ID and can handle two unicast keys per station for Rx and Tx.
*
* @NUM_IEEE80211_HW_FLAGS: number of hardware flags, used for sizing arrays
*/
enum ieee80211_hw_flags {
@ -2294,6 +2299,7 @@ enum ieee80211_hw_flags {
IEEE80211_HW_TX_STATUS_NO_AMPDU_LEN,
IEEE80211_HW_SUPPORTS_MULTI_BSSID,
IEEE80211_HW_SUPPORTS_ONLY_HE_MULTI_BSSID,
IEEE80211_HW_EXT_KEY_ID_NATIVE,
/* keep last, obviously */
NUM_IEEE80211_HW_FLAGS

36
net/mac80211/cfg.c
View File

@ -351,6 +351,36 @@ static int ieee80211_set_noack_map(struct wiphy *wiphy,
return 0;
}
static int ieee80211_set_tx(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 = -EINVAL;
if (!wiphy_ext_feature_isset(local->hw.wiphy,
NL80211_EXT_FEATURE_EXT_KEY_ID))
return -EINVAL;
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->conf.flags & IEEE80211_KEY_FLAG_NO_AUTO_TX)
ret = ieee80211_set_tx_key(key);
mutex_unlock(&local->key_mtx);
return ret;
}
static int ieee80211_add_key(struct wiphy *wiphy, struct net_device *dev,
u8 key_idx, bool pairwise, const u8 *mac_addr,
struct key_params *params)
@ -365,6 +395,9 @@ static int ieee80211_add_key(struct wiphy *wiphy, struct net_device *dev,
if (!ieee80211_sdata_running(sdata))
return -ENETDOWN;
if (pairwise && params->mode == NL80211_KEY_SET_TX)
return ieee80211_set_tx(sdata, mac_addr, key_idx);
/* reject WEP and TKIP keys if WEP failed to initialize */
switch (params->cipher) {
case WLAN_CIPHER_SUITE_WEP40:
@ -396,6 +429,9 @@ static int ieee80211_add_key(struct wiphy *wiphy, struct net_device *dev,
if (pairwise)
key->conf.flags |= IEEE80211_KEY_FLAG_PAIRWISE;
if (params->mode == NL80211_KEY_NO_TX)
key->conf.flags |= IEEE80211_KEY_FLAG_NO_AUTO_TX;
mutex_lock(&local->sta_mtx);
if (mac_addr) {

1
net/mac80211/debugfs.c
View File

@ -221,6 +221,7 @@ static const char *hw_flag_names[] = {
FLAG(TX_STATUS_NO_AMPDU_LEN),
FLAG(SUPPORTS_MULTI_BSSID),
FLAG(SUPPORTS_ONLY_HE_MULTI_BSSID),
FLAG(EXT_KEY_ID_NATIVE),
#undef FLAG
};

2
net/mac80211/ieee80211_i.h
View File

@ -1269,7 +1269,7 @@ struct ieee80211_local {
/*
* Key mutex, protects sdata's key_list and sta_info's
* key pointers (write access, they're RCU.)
* key pointers and ptk_idx (write access, they're RCU.)
*/
struct mutex key_mtx;

63
net/mac80211/key.c
View File

@ -265,9 +265,24 @@ static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
sta ? sta->sta.addr : bcast_addr, ret);
}
int ieee80211_set_tx_key(struct ieee80211_key *key)
{
struct sta_info *sta = key->sta;
struct ieee80211_local *local = key->local;
struct ieee80211_key *old;
assert_key_lock(local);
old = key_mtx_dereference(local, sta->ptk[sta->ptk_idx]);
sta->ptk_idx = key->conf.keyidx;
ieee80211_check_fast_xmit(sta);
return 0;
}
static int ieee80211_hw_key_replace(struct ieee80211_key *old_key,
struct ieee80211_key *new_key,
bool ptk0rekey)
bool pairwise)
{
struct ieee80211_sub_if_data *sdata;
struct ieee80211_local *local;
@ -284,8 +299,9 @@ static int ieee80211_hw_key_replace(struct ieee80211_key *old_key,
assert_key_lock(old_key->local);
sta = old_key->sta;
/* PTK only using key ID 0 needs special handling on rekey */
if (new_key && sta && ptk0rekey) {
/* Unicast rekey without Extended Key ID needs special handling */
if (new_key && sta && pairwise &&
rcu_access_pointer(sta->ptk[sta->ptk_idx]) == old_key) {
local = old_key->local;
sdata = old_key->sdata;
@ -401,10 +417,6 @@ static int ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
if (old) {
idx = old->conf.keyidx;
/* TODO: proper implement and test "Extended Key ID for
* Individually Addressed Frames" from IEEE 802.11-2016.
* Till then always assume only key ID 0 is used for
* pairwise keys.*/
ret = ieee80211_hw_key_replace(old, new, pairwise);
} else {
/* new must be provided in case old is not */
@ -421,15 +433,20 @@ static int ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
if (sta) {
if (pairwise) {
rcu_assign_pointer(sta->ptk[idx], new);
sta->ptk_idx = idx;
if (new) {
if (new &&
!(new->conf.flags & IEEE80211_KEY_FLAG_NO_AUTO_TX)) {
sta->ptk_idx = idx;
clear_sta_flag(sta, WLAN_STA_BLOCK_BA);
ieee80211_check_fast_xmit(sta);
}
} else {
rcu_assign_pointer(sta->gtk[idx], new);
}
if (new)
/* Only needed for transition from no key -> key.
* Still triggers unnecessary when using Extended Key ID
* and installing the second key ID the first time.
*/
if (new && !old)
ieee80211_check_fast_rx(sta);
} else {
defunikey = old &&
@ -745,16 +762,34 @@ int ieee80211_key_link(struct ieee80211_key *key,
* can cause warnings to appear.
*/
bool delay_tailroom = sdata->vif.type == NL80211_IFTYPE_STATION;
int ret;
int ret = -EOPNOTSUPP;
mutex_lock(&sdata->local->key_mtx);
if (sta && pairwise)
if (sta && pairwise) {
struct ieee80211_key *alt_key;
old_key = key_mtx_dereference(sdata->local, sta->ptk[idx]);
else if (sta)
alt_key = key_mtx_dereference(sdata->local, sta->ptk[idx ^ 1]);
/* The rekey code assumes that the old and new key are using
* the same cipher. Enforce the assumption for pairwise keys.
*/
if (key &&
((alt_key && alt_key->conf.cipher != key->conf.cipher) ||
(old_key && old_key->conf.cipher != key->conf.cipher)))
goto out;
} else if (sta) {
old_key = key_mtx_dereference(sdata->local, sta->gtk[idx]);
else
} else {
old_key = key_mtx_dereference(sdata->local, sdata->keys[idx]);
}
/* Non-pairwise keys must also not switch the cipher on rekey */
if (!pairwise) {
if (key && old_key && old_key->conf.cipher != key->conf.cipher)
goto out;
}
/*
* Silently accept key re-installation without really installing the

2
net/mac80211/key.h
View File

@ -18,6 +18,7 @@
#define NUM_DEFAULT_KEYS 4
#define NUM_DEFAULT_MGMT_KEYS 2
#define INVALID_PTK_KEYIDX 2 /* Keyidx always pointing to a NULL key for PTK */
struct ieee80211_local;
struct ieee80211_sub_if_data;
@ -146,6 +147,7 @@ ieee80211_key_alloc(u32 cipher, int idx, size_t key_len,
int ieee80211_key_link(struct ieee80211_key *key,
struct ieee80211_sub_if_data *sdata,
struct sta_info *sta);
int ieee80211_set_tx_key(struct ieee80211_key *key);
void ieee80211_key_free(struct ieee80211_key *key, bool delay_tailroom);
void ieee80211_key_free_unused(struct ieee80211_key *key);
void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx,

5
net/mac80211/main.c
View File

@ -1051,6 +1051,11 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
}
}
if (!local->ops->set_key ||
ieee80211_hw_check(&local->hw, EXT_KEY_ID_NATIVE))
wiphy_ext_feature_set(local->hw.wiphy,
NL80211_EXT_FEATURE_EXT_KEY_ID);
/*
* Calculate scan IE length -- we need this to alloc
* memory and to subtract from the driver limit. It

74
net/mac80211/rx.c
View File

@ -1005,23 +1005,43 @@ static int ieee80211_get_mmie_keyidx(struct sk_buff *skb)
return -1;
}
static int ieee80211_get_cs_keyid(const struct ieee80211_cipher_scheme *cs,
struct sk_buff *skb)
static int ieee80211_get_keyid(struct sk_buff *skb,
const struct ieee80211_cipher_scheme *cs)
{
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
__le16 fc;
int hdrlen;
int minlen;
u8 key_idx_off;
u8 key_idx_shift;
u8 keyid;
fc = hdr->frame_control;
hdrlen = ieee80211_hdrlen(fc);
if (skb->len < hdrlen + cs->hdr_len)
if (cs) {
minlen = hdrlen + cs->hdr_len;
key_idx_off = hdrlen + cs->key_idx_off;
key_idx_shift = cs->key_idx_shift;
} else {
/* WEP, TKIP, CCMP and GCMP */
minlen = hdrlen + IEEE80211_WEP_IV_LEN;
key_idx_off = hdrlen + 3;
key_idx_shift = 6;
}
if (unlikely(skb->len < minlen))
return -EINVAL;
skb_copy_bits(skb, hdrlen + cs->key_idx_off, &keyid, 1);
keyid &= cs->key_idx_mask;
keyid >>= cs->key_idx_shift;
skb_copy_bits(skb, key_idx_off, &keyid, 1);
if (cs)
keyid &= cs->key_idx_mask;
keyid >>= key_idx_shift;
/* cs could use more than the usual two bits for the keyid */
if (unlikely(keyid >= NUM_DEFAULT_KEYS))
return -EINVAL;
return keyid;
}
@ -1852,9 +1872,9 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
int keyidx;
int hdrlen;
ieee80211_rx_result result = RX_DROP_UNUSABLE;
struct ieee80211_key *sta_ptk = NULL;
struct ieee80211_key *ptk_idx = NULL;
int mmie_keyidx = -1;
__le16 fc;
const struct ieee80211_cipher_scheme *cs = NULL;
@ -1892,21 +1912,24 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
if (rx->sta) {
int keyid = rx->sta->ptk_idx;
sta_ptk = rcu_dereference(rx->sta->ptk[keyid]);
if (ieee80211_has_protected(fc) && rx->sta->cipher_scheme) {
if (ieee80211_has_protected(fc)) {
cs = rx->sta->cipher_scheme;
keyid = ieee80211_get_cs_keyid(cs, rx->skb);
keyid = ieee80211_get_keyid(rx->skb, cs);
if (unlikely(keyid < 0))
return RX_DROP_UNUSABLE;
ptk_idx = rcu_dereference(rx->sta->ptk[keyid]);
}
sta_ptk = rcu_dereference(rx->sta->ptk[keyid]);
}
if (!ieee80211_has_protected(fc))
mmie_keyidx = ieee80211_get_mmie_keyidx(rx->skb);
if (!is_multicast_ether_addr(hdr->addr1) && sta_ptk) {
rx->key = sta_ptk;
rx->key = ptk_idx ? ptk_idx : sta_ptk;
if ((status->flag & RX_FLAG_DECRYPTED) &&
(status->flag & RX_FLAG_IV_STRIPPED))
return RX_CONTINUE;
@ -1966,8 +1989,6 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
}
return RX_CONTINUE;
} else {
u8 keyid;
/*
* The device doesn't give us the IV so we won't be
* able to look up the key. That's ok though, we
@ -1981,23 +2002,10 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
(status->flag & RX_FLAG_IV_STRIPPED))
return RX_CONTINUE;
hdrlen = ieee80211_hdrlen(fc);
keyidx = ieee80211_get_keyid(rx->skb, cs);
if (cs) {
keyidx = ieee80211_get_cs_keyid(cs, rx->skb);
if (unlikely(keyidx < 0))
return RX_DROP_UNUSABLE;
} else {
if (rx->skb->len < 8 + hdrlen)
return RX_DROP_UNUSABLE; /* TODO: count this? */
/*
* no need to call ieee80211_wep_get_keyidx,
* it verifies a bunch of things we've done already
*/
skb_copy_bits(rx->skb, hdrlen + 3, &keyid, 1);
keyidx = keyid >> 6;
}
if (unlikely(keyidx < 0))
return RX_DROP_UNUSABLE;
/* check per-station GTK first, if multicast packet */
if (is_multicast_ether_addr(hdr->addr1) && rx->sta)
@ -4042,12 +4050,8 @@ void ieee80211_check_fast_rx(struct sta_info *sta)
case WLAN_CIPHER_SUITE_GCMP_256:
break;
default:
/* we also don't want to deal with WEP or cipher scheme
* since those require looking up the key idx in the
* frame, rather than assuming the PTK is used
* (we need to revisit this once we implement the real
* PTK index, which is now valid in the spec, but we
* haven't implemented that part yet)
/* We also don't want to deal with
* WEP or cipher scheme.
*/
goto clear_rcu;
}

9
net/mac80211/sta_info.c
View File

@ -347,6 +347,15 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
sta->sta.max_rx_aggregation_subframes =
local->hw.max_rx_aggregation_subframes;
/* Extended Key ID needs to install keys for keyid 0 and 1 Rx-only.
* The Tx path starts to use a key as soon as the key slot ptk_idx
* references to is not NULL. To not use the initial Rx-only key
* prematurely for Tx initialize ptk_idx to an impossible PTK keyid
* which always will refer to a NULL key.
*/
BUILD_BUG_ON(ARRAY_SIZE(sta->ptk) <= INVALID_PTK_KEYIDX);
sta->ptk_idx = INVALID_PTK_KEYIDX;
sta->local = local;
sta->sdata = sdata;
sta->rx_stats.last_rx = jiffies;

13
net/mac80211/tx.c
View File

@ -3001,23 +3001,15 @@ 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;
@ -3388,6 +3380,7 @@ 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;