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Normally wouldn't cross-post, but at first I thought this was a bug
in the cfg80211 kernel module, but the more I thought about it the
more it seemed to be a bug in the libnl API itself.<br>
<br>
Can someone who understands this better than me weigh in?<br>
<br>
Thanks.<br>
<br>
-Philip<br>
<br>
<br>
-------- Original Message --------
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<th nowrap="nowrap" valign="BASELINE" align="RIGHT">Subject: </th>
<td>Re: [PATCH 3/3] nl80211: New command for setting TX rate
mask for rate control</td>
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<th nowrap="nowrap" valign="BASELINE" align="RIGHT">Date: </th>
<td>Thu, 19 Aug 2010 14:26:51 -0700</td>
</tr>
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<th nowrap="nowrap" valign="BASELINE" align="RIGHT">From: </th>
<td>Philip Prindeville
<a class="moz-txt-link-rfc2396E" href="mailto:philipp_subx@redfish-solutions.com"><philipp_subx@redfish-solutions.com></a></td>
</tr>
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<th nowrap="nowrap" valign="BASELINE" align="RIGHT">To: </th>
<td>Jouni Malinen <a class="moz-txt-link-rfc2396E" href="mailto:jouni.malinen@atheros.com"><jouni.malinen@atheros.com></a></td>
</tr>
<tr>
<th nowrap="nowrap" valign="BASELINE" align="RIGHT">CC: </th>
<td>John W. Linville <a class="moz-txt-link-rfc2396E" href="mailto:linville@tuxdriver.com"><linville@tuxdriver.com></a>, Johannes
Berg <a class="moz-txt-link-rfc2396E" href="mailto:johannes@sipsolutions.net"><johannes@sipsolutions.net></a>,
<a class="moz-txt-link-abbreviated" href="mailto:linux-wireless@vger.kernel.org">linux-wireless@vger.kernel.org</a>, Jouni Malinen
<a class="moz-txt-link-rfc2396E" href="mailto:j@w1.fi"><j@w1.fi></a></td>
</tr>
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<br>
<br>
<pre> On 12/29/09 2:59 AM, Jouni Malinen wrote:
> Add a new NL80211_CMD_SET_TX_BITRATE_MASK command and related
> attributes to provide support for setting TX rate mask for rate
> control. This uses the existing cfg80211 set_bitrate_mask operation
> that was previously used only with WEXT compat code (SIOCSIWRATE). The
> nl80211 command allows more generic configuration of allowed rates as
> a mask instead of fixed/max rate.
>
> Signed-off-by: Jouni Malinen<a class="moz-txt-link-rfc2396E" href="mailto:jouni.malinen@atheros.com"><jouni.malinen@atheros.com></a>
>
> ---
> include/linux/nl80211.h | 44 +++++++++++++++++++
> include/net/cfg80211.h | 4 -
> net/wireless/nl80211.c | 111 ++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 157 insertions(+), 2 deletions(-)
>
> --- wireless-testing.orig/include/linux/nl80211.h 2009-12-29 10:50:56.000000000 +0200
> +++ wireless-testing/include/linux/nl80211.h 2009-12-29 10:56:42.000000000 +0200
> @@ -295,6 +295,10 @@
> * This command is also used as an event to notify when a requested
> * remain-on-channel duration has expired.
> *
> + * @NL80211_CMD_SET_TX_BITRATE_MASK: Set the mask of rates to be used in TX
> + * rate selection. %NL80211_ATTR_IFINDEX is used to specify the interface
> + * and @NL80211_ATTR_TX_RATES the set of allowed rates.
> + *
> * @NL80211_CMD_MAX: highest used command number
> * @__NL80211_CMD_AFTER_LAST: internal use
> */
> @@ -381,6 +385,8 @@ enum nl80211_commands {
> NL80211_CMD_REMAIN_ON_CHANNEL,
> NL80211_CMD_CANCEL_REMAIN_ON_CHANNEL,
>
> + NL80211_CMD_SET_TX_BITRATE_MASK,
> +
> /* add new commands above here */
>
> /* used to define NL80211_CMD_MAX below */
> @@ -638,6 +644,13 @@ enum nl80211_commands {
> *
> * @NL80211_ATTR_COOKIE: Generic 64-bit cookie to identify objects.
> *
> + * @NL80211_ATTR_TX_RATES: Nested set of attributes
> + * (enum nl80211_tx_rate_attributes) describing TX rates per band. The
> + * enum nl80211_band value is used as the index (nla_type() of the nested
> + * data. If a band is not included, it will be configured to allow all
> + * rates based on negotiated supported rates information. This attribute
> + * is used with %NL80211_CMD_SET_TX_BITRATE_MASK.
> + *
> * @NL80211_ATTR_MAX: highest attribute number currently defined
> * @__NL80211_ATTR_AFTER_LAST: internal use
> */
> @@ -779,6 +792,8 @@ enum nl80211_attrs {
>
> NL80211_ATTR_COOKIE,
>
> + NL80211_ATTR_TX_RATES,
> +
> /* add attributes here, update the policy in nl80211.c */
>
> __NL80211_ATTR_AFTER_LAST,
> @@ -1478,4 +1493,33 @@ enum nl80211_key_attributes {
> NL80211_KEY_MAX = __NL80211_KEY_AFTER_LAST - 1
> };
>
> +/**
> + * enum nl80211_tx_rate_attributes - TX rate set attributes
> + * @__NL80211_TXRATE_INVALID: invalid
> + * @NL80211_TXRATE_LEGACY: Legacy (non-MCS) rates allowed for TX rate selection
> + * in an array of rates as defined in IEEE 802.11 7.3.2.2 (u8 values with
> + * 1 = 500 kbps) but without the IE length restriction (at most
> + * %NL80211_MAX_SUPP_RATES in a single array).
> + * @__NL80211_TXRATE_AFTER_LAST: internal
> + * @NL80211_TXRATE_MAX: highest TX rate attribute
> + */
> +enum nl80211_tx_rate_attributes {
> + __NL80211_TXRATE_INVALID,
> + NL80211_TXRATE_LEGACY,
> +
> + /* keep last */
> + __NL80211_TXRATE_AFTER_LAST,
> + NL80211_TXRATE_MAX = __NL80211_TXRATE_AFTER_LAST - 1
> +};
> +
> +/**
> + * enum nl80211_band - Frequency band
> + * @NL80211_BAND_2GHZ - 2.4 GHz ISM band
> + * @NL80211_BAND_5GHZ - around 5 GHz band (4.9 - 5.7 GHz)
> + */
> +enum nl80211_band {
> + NL80211_BAND_2GHZ,
> + NL80211_BAND_5GHZ,
> +};
> +
> #endif /* __LINUX_NL80211_H */
> --- wireless-testing.orig/net/wireless/nl80211.c 2009-12-29 10:50:57.000000000 +0200
> +++ wireless-testing/net/wireless/nl80211.c 2009-12-29 10:57:37.000000000 +0200
> @@ -143,6 +143,7 @@ static struct nla_policy nl80211_policy[
> .len = WLAN_PMKID_LEN },
> [NL80211_ATTR_DURATION] = { .type = NLA_U32 },
> [NL80211_ATTR_COOKIE] = { .type = NLA_U64 },
> + [NL80211_ATTR_TX_RATES] = { .type = NLA_NESTED },
> };
>
> /* policy for the attributes */
> @@ -572,6 +573,7 @@ static int nl80211_send_wiphy(struct sk_
> CMD(del_pmksa, DEL_PMKSA);
> CMD(flush_pmksa, FLUSH_PMKSA);
> CMD(remain_on_channel, REMAIN_ON_CHANNEL);
> + CMD(set_bitrate_mask, SET_TX_BITRATE_MASK);
> if (dev->wiphy.flags& WIPHY_FLAG_NETNS_OK) {
> i++;
> NLA_PUT_U32(msg, i, NL80211_CMD_SET_WIPHY_NETNS);
> @@ -4423,6 +4425,109 @@ static int nl80211_cancel_remain_on_chan
> return err;
> }
>
> +static u32 rateset_to_mask(struct ieee80211_supported_band *sband,
> + u8 *rates, u8 rates_len)
> +{
> + u8 i;
> + u32 mask = 0;
> +
> + for (i = 0; i< rates_len; i++) {
> + int rate = (rates[i]& 0x7f) * 5;
> + int ridx;
> + for (ridx = 0; ridx< sband->n_bitrates; ridx++) {
> + struct ieee80211_rate *srate =
> + &sband->bitrates[ridx];
> + if (rate == srate->bitrate) {
> + mask |= 1<< ridx;
> + break;
> + }
> + }
> + if (ridx == sband->n_bitrates)
> + return 0; /* rate not found */
> + }
> +
> + return mask;
> +}
> +
> +static struct nla_policy
> +nl80211_txattr_policy[NL80211_TXRATE_MAX + 1] __read_mostly = {
> + [NL80211_TXRATE_LEGACY] = { .type = NLA_BINARY,
> + .len = NL80211_MAX_SUPP_RATES },
> +};
> +
> +static int nl80211_set_tx_bitrate_mask(struct sk_buff *skb,
> + struct genl_info *info)
> +{
> + struct nlattr *tb[NL80211_TXRATE_MAX + 1];
> + struct cfg80211_registered_device *rdev;
> + struct cfg80211_bitrate_mask mask;
> + int err, rem, i;
> + struct net_device *dev;
> + struct nlattr *tx_rates;
> + struct ieee80211_supported_band *sband;
> +
> + if (info->attrs[NL80211_ATTR_TX_RATES] == NULL)
> + return -EINVAL;
> +
> + rtnl_lock();
> +
> + err = get_rdev_dev_by_info_ifindex(info,&rdev,&dev);
> + if (err)
> + goto unlock_rtnl;
> +
> + if (!rdev->ops->set_bitrate_mask) {
> + err = -EOPNOTSUPP;
> + goto unlock;
> + }
> +
> + memset(&mask, 0, sizeof(mask));
> + /* Default to all rates enabled */
> + for (i = 0; i< IEEE80211_NUM_BANDS; i++) {
> + sband = rdev->wiphy.bands[i];
> + mask.control[i].legacy =
> + sband ? (1<< sband->n_bitrates) - 1 : 0;
> + }
> +
> + /*
> + * The nested attribute uses enum nl80211_band as the index. This maps
> + * directly to the enum ieee80211_band values used in cfg80211.
> + */
> + nla_for_each_nested(tx_rates, info->attrs[NL80211_ATTR_TX_RATES], rem)
> + {
> + enum ieee80211_band band = nla_type(tx_rates);
Can this even work? The first entry in nl80211_band is NL80211_BAND_2GHZ, i.e. zero.
Yet looking at libnl-1.1/lib/attr.c there's:
int nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head, int len,
struct nla_policy *policy)
{
...
nla_for_each_attr(nla, head, len, rem) {
int type = nla_type(nla);
if (type == 0) {
fprintf(stderr, "Illegal nla->nla_type == 0\n");
continue;
}
so any time nla->nla_type is set to NL80211_BAND_2GHZ, isn't this going to be problematic?
Or am I misreading this code?
-Philip
> + if (band< 0 || band>= IEEE80211_NUM_BANDS) {
> + err = -EINVAL;
> + goto unlock;
> + }
> + sband = rdev->wiphy.bands[band];
> + if (sband == NULL) {
> + err = -EINVAL;
> + goto unlock;
> + }
> + nla_parse(tb, NL80211_TXRATE_MAX, nla_data(tx_rates),
> + nla_len(tx_rates), nl80211_txattr_policy);
> + if (tb[NL80211_TXRATE_LEGACY]) {
> + mask.control[band].legacy = rateset_to_mask(
> + sband,
> + nla_data(tb[NL80211_TXRATE_LEGACY]),
> + nla_len(tb[NL80211_TXRATE_LEGACY]));
> + if (mask.control[band].legacy == 0) {
> + err = -EINVAL;
> + goto unlock;
> + }
> + }
> + }
> +
> + err = rdev->ops->set_bitrate_mask(&rdev->wiphy, dev, NULL,&mask);
> +
> + unlock:
> + dev_put(dev);
> + cfg80211_unlock_rdev(rdev);
> + unlock_rtnl:
> + rtnl_unlock();
> + return err;
> +}
> +
> static struct genl_ops nl80211_ops[] = {
> {
> .cmd = NL80211_CMD_GET_WIPHY,
> @@ -4697,6 +4802,12 @@ static struct genl_ops nl80211_ops[] = {
> .policy = nl80211_policy,
> .flags = GENL_ADMIN_PERM,
> },
> + {
> + .cmd = NL80211_CMD_SET_TX_BITRATE_MASK,
> + .doit = nl80211_set_tx_bitrate_mask,
> + .policy = nl80211_policy,
> + .flags = GENL_ADMIN_PERM,
> + },
> };
>
> static struct genl_multicast_group nl80211_mlme_mcgrp = {
> --- wireless-testing.orig/include/net/cfg80211.h 2009-12-29 10:54:29.000000000 +0200
> +++ wireless-testing/include/net/cfg80211.h 2009-12-29 10:55:52.000000000 +0200
> @@ -39,8 +39,8 @@
> * @IEEE80211_BAND_5GHZ: around 5GHz band (4.9-5.7)
> */
> enum ieee80211_band {
> - IEEE80211_BAND_2GHZ,
> - IEEE80211_BAND_5GHZ,
> + IEEE80211_BAND_2GHZ = NL80211_BAND_2GHZ,
> + IEEE80211_BAND_5GHZ = NL80211_BAND_5GHZ,
>
> /* keep last */
> IEEE80211_NUM_BANDS
>
--
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