Commit 2d946308 authored by Anant Thazhemadam's avatar Anant Thazhemadam Committed by Johannes Berg
Browse files

nl80211: validate key indexes for cfg80211_registered_device 



syzbot discovered a bug in which an OOB access was being made because
an unsuitable key_idx value was wrongly considered to be acceptable
while deleting a key in nl80211_del_key().

Since we don't know the cipher at the time of deletion, if
cfg80211_validate_key_settings() were to be called directly in
nl80211_del_key(), even valid keys would be wrongly determined invalid,
and deletion wouldn't occur correctly.
For this reason, a new function - cfg80211_valid_key_idx(), has been
created, to determine if the key_idx value provided is valid or not.
cfg80211_valid_key_idx() is directly called in 2 places -
nl80211_del_key(), and cfg80211_validate_key_settings().

Reported-by: default avatar <syzbot+49d4cab497c2142ee170@syzkaller.appspotmail.com>
Tested-by: default avatar <syzbot+49d4cab497c2142ee170@syzkaller.appspotmail.com>
Suggested-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarAnant Thazhemadam <anant.thazhemadam@gmail.com>
Link: https://lore.kernel.org/r/20201204215825.129879-1-anant.thazhemadam@gmail.com


Cc: stable@vger.kernel.org
[also disallow IGTK key IDs if no IGTK cipher is supported]
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 669b8413

net/wireless/core.h

+2 −0
Original line number Diff line number Diff line
@@ -433,6 +433,8 @@ void cfg80211_sme_abandon_assoc(struct wireless_dev *wdev); 


/* internal helpers */

bool cfg80211_supported_cipher_suite(struct wiphy *wiphy, u32 cipher);

bool cfg80211_valid_key_idx(struct cfg80211_registered_device *rdev,

			    int key_idx, bool pairwise);

int cfg80211_validate_key_settings(struct cfg80211_registered_device *rdev,

				   struct key_params *params, int key_idx,

				   bool pairwise, const u8 *mac_addr);

net/wireless/nl80211.c

+4 −3
Original line number Diff line number Diff line
@@ -4239,9 +4239,6 @@ static int nl80211_del_key(struct sk_buff *skb, struct genl_info *info) 
	if (err)

		return err;



	if (key.idx < 0)

		return -EINVAL;



	if (info->attrs[NL80211_ATTR_MAC])

		mac_addr = nla_data(info->attrs[NL80211_ATTR_MAC]);
@@ -4257,6 +4254,10 @@ static int nl80211_del_key(struct sk_buff *skb, struct genl_info *info) 
	    key.type != NL80211_KEYTYPE_GROUP)

		return -EINVAL;



	if (!cfg80211_valid_key_idx(rdev, key.idx,

				    key.type == NL80211_KEYTYPE_PAIRWISE))

		return -EINVAL;



	if (!rdev->ops->del_key)

		return -EOPNOTSUPP;

net/wireless/util.c

+43 −8
Original line number Diff line number Diff line
@@ -272,18 +272,53 @@ bool cfg80211_supported_cipher_suite(struct wiphy *wiphy, u32 cipher) 
	return false;

}



int cfg80211_validate_key_settings(struct cfg80211_registered_device *rdev,

				   struct key_params *params, int key_idx,

				   bool pairwise, const u8 *mac_addr)

static bool

cfg80211_igtk_cipher_supported(struct cfg80211_registered_device *rdev)

{

	int max_key_idx = 5;

	struct wiphy *wiphy = &rdev->wiphy;

	int i;



	if (wiphy_ext_feature_isset(&rdev->wiphy,

	for (i = 0; i < wiphy->n_cipher_suites; i++) {

		switch (wiphy->cipher_suites[i]) {

		case WLAN_CIPHER_SUITE_AES_CMAC:

		case WLAN_CIPHER_SUITE_BIP_CMAC_256:

		case WLAN_CIPHER_SUITE_BIP_GMAC_128:

		case WLAN_CIPHER_SUITE_BIP_GMAC_256:

			return true;

		}

	}



	return false;

}



bool cfg80211_valid_key_idx(struct cfg80211_registered_device *rdev,

			    int key_idx, bool pairwise)

{

	int max_key_idx;



	if (pairwise)

		max_key_idx = 3;

	else if (wiphy_ext_feature_isset(&rdev->wiphy,

					 NL80211_EXT_FEATURE_BEACON_PROTECTION) ||

		 wiphy_ext_feature_isset(&rdev->wiphy,

					 NL80211_EXT_FEATURE_BEACON_PROTECTION_CLIENT))

		max_key_idx = 7;

	else if (cfg80211_igtk_cipher_supported(rdev))

		max_key_idx = 5;

	else

		max_key_idx = 3;



	if (key_idx < 0 || key_idx > max_key_idx)

		return false;



	return true;

}



int cfg80211_validate_key_settings(struct cfg80211_registered_device *rdev,

				   struct key_params *params, int key_idx,

				   bool pairwise, const u8 *mac_addr)

{

	if (!cfg80211_valid_key_idx(rdev, key_idx, pairwise))

		return -EINVAL;



	if (!pairwise && mac_addr && !(rdev->wiphy.flags & WIPHY_FLAG_IBSS_RSN))

CRA Git | Maintained and supported by SUSTech CRA and CCSE