linux/net/mac80211/key.h
Mathy Vanhoef 76ffc27967 mac80211: prevent mixed key and fragment cache attacks
commit 94034c40ab upstream.

Simultaneously prevent mixed key attacks (CVE-2020-24587) and fragment
cache attacks (CVE-2020-24586). This is accomplished by assigning a
unique color to every key (per interface) and using this to track which
key was used to decrypt a fragment. When reassembling frames, it is
now checked whether all fragments were decrypted using the same key.

To assure that fragment cache attacks are also prevented, the ID that is
assigned to keys is unique even over (re)associations and (re)connects.
This means fragments separated by a (re)association or (re)connect will
not be reassembled. Because mac80211 now also prevents the reassembly of
mixed encrypted and plaintext fragments, all cache attacks are prevented.

Cc: stable@vger.kernel.org
Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>
Link: https://lore.kernel.org/r/20210511200110.3f8290e59823.I622a67769ed39257327a362cfc09c812320eb979@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-06-03 08:38:03 +02:00

170 lines
4.6 KiB
C

/*
* Copyright 2002-2004, Instant802 Networks, Inc.
* Copyright 2005, Devicescape Software, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef IEEE80211_KEY_H
#define IEEE80211_KEY_H
#include <linux/types.h>
#include <linux/list.h>
#include <linux/crypto.h>
#include <linux/rcupdate.h>
#include <net/mac80211.h>
#define NUM_DEFAULT_KEYS 4
#define NUM_DEFAULT_MGMT_KEYS 2
struct ieee80211_local;
struct ieee80211_sub_if_data;
struct sta_info;
/**
* enum ieee80211_internal_key_flags - internal key flags
*
* @KEY_FLAG_UPLOADED_TO_HARDWARE: Indicates that this key is present
* in the hardware for TX crypto hardware acceleration.
* @KEY_FLAG_TAINTED: Key is tainted and packets should be dropped.
* @KEY_FLAG_CIPHER_SCHEME: This key is for a hardware cipher scheme
*/
enum ieee80211_internal_key_flags {
KEY_FLAG_UPLOADED_TO_HARDWARE = BIT(0),
KEY_FLAG_TAINTED = BIT(1),
KEY_FLAG_CIPHER_SCHEME = BIT(2),
};
enum ieee80211_internal_tkip_state {
TKIP_STATE_NOT_INIT,
TKIP_STATE_PHASE1_DONE,
TKIP_STATE_PHASE1_HW_UPLOADED,
};
struct tkip_ctx {
u16 p1k[5]; /* p1k cache */
u32 p1k_iv32; /* iv32 for which p1k computed */
enum ieee80211_internal_tkip_state state;
};
struct tkip_ctx_rx {
struct tkip_ctx ctx;
u32 iv32; /* current iv32 */
u16 iv16; /* current iv16 */
};
struct ieee80211_key {
struct ieee80211_local *local;
struct ieee80211_sub_if_data *sdata;
struct sta_info *sta;
/* for sdata list */
struct list_head list;
/* protected by key mutex */
unsigned int flags;
union {
struct {
/* protects tx context */
spinlock_t txlock;
/* last used TSC */
struct tkip_ctx tx;
/* last received RSC */
struct tkip_ctx_rx rx[IEEE80211_NUM_TIDS];
/* number of mic failures */
u32 mic_failures;
} tkip;
struct {
/*
* Last received packet number. The first
* IEEE80211_NUM_TIDS counters are used with Data
* frames and the last counter is used with Robust
* Management frames.
*/
u8 rx_pn[IEEE80211_NUM_TIDS + 1][IEEE80211_CCMP_PN_LEN];
struct crypto_aead *tfm;
u32 replays; /* dot11RSNAStatsCCMPReplays */
} ccmp;
struct {
u8 rx_pn[IEEE80211_CMAC_PN_LEN];
struct crypto_shash *tfm;
u32 replays; /* dot11RSNAStatsCMACReplays */
u32 icverrors; /* dot11RSNAStatsCMACICVErrors */
} aes_cmac;
struct {
u8 rx_pn[IEEE80211_GMAC_PN_LEN];
struct crypto_aead *tfm;
u32 replays; /* dot11RSNAStatsCMACReplays */
u32 icverrors; /* dot11RSNAStatsCMACICVErrors */
} aes_gmac;
struct {
/* Last received packet number. The first
* IEEE80211_NUM_TIDS counters are used with Data
* frames and the last counter is used with Robust
* Management frames.
*/
u8 rx_pn[IEEE80211_NUM_TIDS + 1][IEEE80211_GCMP_PN_LEN];
struct crypto_aead *tfm;
u32 replays; /* dot11RSNAStatsGCMPReplays */
} gcmp;
struct {
/* generic cipher scheme */
u8 rx_pn[IEEE80211_NUM_TIDS + 1][IEEE80211_MAX_PN_LEN];
} gen;
} u;
#ifdef CONFIG_MAC80211_DEBUGFS
struct {
struct dentry *stalink;
struct dentry *dir;
int cnt;
} debugfs;
#endif
unsigned int color;
/*
* key config, must be last because it contains key
* material as variable length member
*/
struct ieee80211_key_conf conf;
};
struct ieee80211_key *
ieee80211_key_alloc(u32 cipher, int idx, size_t key_len,
const u8 *key_data,
size_t seq_len, const u8 *seq,
const struct ieee80211_cipher_scheme *cs);
/*
* Insert a key into data structures (sdata, sta if necessary)
* to make it used, free old key. On failure, also free the new key.
*/
int ieee80211_key_link(struct ieee80211_key *key,
struct ieee80211_sub_if_data *sdata,
struct sta_info *sta);
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,
bool uni, bool multi);
void ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata,
int idx);
void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata,
bool force_synchronize);
void ieee80211_free_sta_keys(struct ieee80211_local *local,
struct sta_info *sta);
void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata);
void ieee80211_reset_crypto_tx_tailroom(struct ieee80211_sub_if_data *sdata);
#define key_mtx_dereference(local, ref) \
rcu_dereference_protected(ref, lockdep_is_held(&((local)->key_mtx)))
void ieee80211_delayed_tailroom_dec(struct work_struct *wk);
#endif /* IEEE80211_KEY_H */