cfg80211: prohibit scanning the same channel more than once
It isn't very useful to scan the same channel more than once during a given scan, and some hardware (notably iwlwifi) can only scan a limited number of channels at a time. To prevent any overflows, simply disallow scanning any channel multiple times in a given scan command. This is a small change in the userspace ABI, but the only user, wpa_supplicant, never asks for a scan with the same frequency listed twice. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>
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@ -2695,6 +2695,31 @@ static int nl80211_set_reg(struct sk_buff *skb, struct genl_info *info)
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return r;
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}
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static int validate_scan_freqs(struct nlattr *freqs)
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{
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struct nlattr *attr1, *attr2;
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int n_channels = 0, tmp1, tmp2;
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nla_for_each_nested(attr1, freqs, tmp1) {
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n_channels++;
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/*
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* Some hardware has a limited channel list for
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* scanning, and it is pretty much nonsensical
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* to scan for a channel twice, so disallow that
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* and don't require drivers to check that the
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* channel list they get isn't longer than what
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* they can scan, as long as they can scan all
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* the channels they registered at once.
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*/
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nla_for_each_nested(attr2, freqs, tmp2)
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if (attr1 != attr2 &&
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nla_get_u32(attr1) == nla_get_u32(attr2))
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return 0;
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}
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return n_channels;
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}
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static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
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{
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struct cfg80211_registered_device *drv;
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@ -2704,7 +2729,7 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
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struct ieee80211_channel *channel;
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struct nlattr *attr;
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struct wiphy *wiphy;
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int err, tmp, n_ssids = 0, n_channels = 0, i;
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int err, tmp, n_ssids = 0, n_channels, i;
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enum ieee80211_band band;
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size_t ie_len;
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@ -2735,13 +2760,15 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
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}
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if (info->attrs[NL80211_ATTR_SCAN_FREQUENCIES]) {
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nla_for_each_nested(attr, info->attrs[NL80211_ATTR_SCAN_FREQUENCIES], tmp)
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n_channels++;
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n_channels = validate_scan_freqs(
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info->attrs[NL80211_ATTR_SCAN_FREQUENCIES]);
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if (!n_channels) {
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err = -EINVAL;
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goto out;
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}
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} else {
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n_channels = 0;
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for (band = 0; band < IEEE80211_NUM_BANDS; band++)
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if (wiphy->bands[band])
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n_channels += wiphy->bands[band]->n_channels;
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