nl80211: validate some input better

This patch changes nl80211 to:
 * validate that any IE input is a valid IE (stream)
 * move some validation code before locking
 * require that a reason code is given for both deauth/disassoc

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 77 insertions, 37 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 2456e4ee445e..2f449ddcbc72 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -118,6 +118,36 @@ static struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] __read_mostly = {
         [NL80211_ATTR_REASON_CODE] = { .type = NLA_U16 },
 };
 
+/* IE validation */
+static bool is_valid_ie_attr(const struct nlattr *attr)
+{
+        const u8 *pos;
+        int len;
+
+        if (!attr)
+                return true;
+
+        pos = nla_data(attr);
+        len = nla_len(attr);
+
+        while (len) {
+                u8 elemlen;
+
+                if (len < 2)
+                        return false;
+                len -= 2;
+
+                elemlen = pos[1];
+                if (elemlen > len)
+                        return false;
+
+                len -= elemlen;
+                pos += 2 + elemlen;
+        }
+
+        return true;
+}
+
 /* message building helper */
 static inline void *nl80211hdr_put(struct sk_buff *skb, u32 pid, u32 seq,
                                    int flags, u8 cmd)
@@ -1069,6 +1099,9 @@ static int nl80211_addset_beacon(struct sk_buff *skb, struct genl_info *info)
         struct beacon_parameters params;
         int haveinfo = 0;
 
+        if (!is_valid_ie_attr(info->attrs[NL80211_ATTR_BEACON_TAIL]))
+                return -EINVAL;
+
         rtnl_lock();
 
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
@@ -2442,6 +2475,9 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
         enum ieee80211_band band;
         size_t ie_len;
 
+        if (!is_valid_ie_attr(info->attrs[NL80211_ATTR_IE]))
+                return -EINVAL;
+
         rtnl_lock();
 
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
@@ -2710,6 +2746,12 @@ static int nl80211_authenticate(struct sk_buff *skb, struct genl_info *info)
         struct wiphy *wiphy;
         int err;
 
+        if (!is_valid_ie_attr(info->attrs[NL80211_ATTR_IE]))
+                return -EINVAL;
+
+        if (!info->attrs[NL80211_ATTR_MAC])
+                return -EINVAL;
+
         rtnl_lock();
 
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
@@ -2731,11 +2773,6 @@ static int nl80211_authenticate(struct sk_buff *skb, struct genl_info *info)
                 goto out;
         }
 
-        if (!info->attrs[NL80211_ATTR_MAC]) {
-                err = -EINVAL;
-                goto out;
-        }
-
         wiphy = &drv->wiphy;
         memset(&req, 0, sizeof(req));
 
@@ -2788,6 +2825,13 @@ static int nl80211_associate(struct sk_buff *skb, struct genl_info *info)
         struct wiphy *wiphy;
         int err;
 
+        if (!is_valid_ie_attr(info->attrs[NL80211_ATTR_IE]))
+                return -EINVAL;
+
+        if (!info->attrs[NL80211_ATTR_MAC] ||
+            !info->attrs[NL80211_ATTR_SSID])
+                return -EINVAL;
+
         rtnl_lock();
 
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
@@ -2809,12 +2853,6 @@ static int nl80211_associate(struct sk_buff *skb, struct genl_info *info)
                 goto out;
         }
 
-        if (!info->attrs[NL80211_ATTR_MAC] ||
-            !info->attrs[NL80211_ATTR_SSID]) {
-                err = -EINVAL;
-                goto out;
-        }
-
         wiphy = &drv->wiphy;
         memset(&req, 0, sizeof(req));
 
@@ -2856,6 +2894,15 @@ static int nl80211_deauthenticate(struct sk_buff *skb, struct genl_info *info)
         struct wiphy *wiphy;
         int err;
 
+        if (!is_valid_ie_attr(info->attrs[NL80211_ATTR_IE]))
+                return -EINVAL;
+
+        if (!info->attrs[NL80211_ATTR_MAC])
+                return -EINVAL;
+
+        if (!info->attrs[NL80211_ATTR_REASON_CODE])
+                return -EINVAL;
+
         rtnl_lock();
 
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
@@ -2877,24 +2924,16 @@ static int nl80211_deauthenticate(struct sk_buff *skb, struct genl_info *info)
                 goto out;
         }
 
-        if (!info->attrs[NL80211_ATTR_MAC]) {
-                err = -EINVAL;
-                goto out;
-        }
-
         wiphy = &drv->wiphy;
         memset(&req, 0, sizeof(req));
 
         req.peer_addr = nla_data(info->attrs[NL80211_ATTR_MAC]);
 
-        if (info->attrs[NL80211_ATTR_REASON_CODE]) {
-                req.reason_code =
-                        nla_get_u16(info->attrs[NL80211_ATTR_REASON_CODE]);
-                if (req.reason_code == 0) {
-                        /* Reason Code 0 is reserved */
-                        err = -EINVAL;
-                        goto out;
-                }
+        req.reason_code = nla_get_u16(info->attrs[NL80211_ATTR_REASON_CODE]);
+        if (req.reason_code == 0) {
+                /* Reason Code 0 is reserved */
+                err = -EINVAL;
+                goto out;
         }
 
         if (info->attrs[NL80211_ATTR_IE]) {
@@ -2920,6 +2959,15 @@ static int nl80211_disassociate(struct sk_buff *skb, struct genl_info *info)
         struct wiphy *wiphy;
         int err;
 
+        if (!is_valid_ie_attr(info->attrs[NL80211_ATTR_IE]))
+                return -EINVAL;
+
+        if (!info->attrs[NL80211_ATTR_MAC])
+                return -EINVAL;
+
+        if (!info->attrs[NL80211_ATTR_REASON_CODE])
+                return -EINVAL;
+
         rtnl_lock();
 
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
@@ -2941,24 +2989,16 @@ static int nl80211_disassociate(struct sk_buff *skb, struct genl_info *info)
                 goto out;
         }
 
-        if (!info->attrs[NL80211_ATTR_MAC]) {
-                err = -EINVAL;
-                goto out;
-        }
-
         wiphy = &drv->wiphy;
         memset(&req, 0, sizeof(req));
 
         req.peer_addr = nla_data(info->attrs[NL80211_ATTR_MAC]);
 
-        if (info->attrs[NL80211_ATTR_REASON_CODE]) {
-                req.reason_code =
-                        nla_get_u16(info->attrs[NL80211_ATTR_REASON_CODE]);
-                if (req.reason_code == 0) {
-                        /* Reason Code 0 is reserved */
-                        err = -EINVAL;
-                        goto out;
-                }
+        req.reason_code = nla_get_u16(info->attrs[NL80211_ATTR_REASON_CODE]);
+        if (req.reason_code == 0) {
+                /* Reason Code 0 is reserved */
+                err = -EINVAL;
+                goto out;
         }
 
         if (info->attrs[NL80211_ATTR_IE]) {