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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: syzbot+49d4cab497c2142ee170@syzkaller.appspotmail.com
Tested-by: syzbot+49d4cab497c2142ee170@syzkaller.appspotmail.com
Suggested-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Anant 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: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Anant Thazhemadam 2020-12-05 03:28:25 +05:30 committed by Johannes Berg
parent 669b84134a
commit 2d9463083c
3 changed files with 49 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
net/wireless/core.h
View File

@ -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);

7
net/wireless/nl80211.c
View File

@ -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;

45
net/wireless/util.c
View File

@ -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))