[RFC 3/4] wifi: nl80211: strict checking attributes for NL80211_CMD_SET_BSS

Assure user-space only modifies attributes for NL80211_CMD_SET_BSS
that are supported by the driver. This stricter checking is only done
when user-space commits to it by including NL80211_ATTR_BSS_PARAM.

Signed-off-by: Arend van Spriel <[email protected]>
---
 include/uapi/linux/nl80211.h |  5 ++++-
 net/wireless/nl80211.c       | 30 +++++++++++++++++++++++++-----
 2 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index b81dffad2f8f..ef35c49c3478 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -2900,7 +2900,10 @@ enum nl80211_commands {
  *	in the kernel or device.
  *
  * @NL80211_ATTR_BSS_PARAM: nested attribute used with %NL80211_CMD_GET_WIPHY
- *	which indicates which BSS parameters can be modified.
+ *	which indicates which BSS parameters can be modified. The attribute can
+ *	also be used as flag attribute by user-space in %NL80211_CMD_SET_BSS to
+ *	indicate that it wants strict checking on the BSS parameters to be
+ *	modified.
  *
  * @NUM_NL80211_ATTR: total number of nl80211_attrs available
  * @NL80211_ATTR_MAX: highest attribute number currently defined
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index bf3cd044de13..686592fabe82 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -854,6 +854,7 @@ static const struct nla_policy nl80211_policy[NUM_NL80211_ATTR] = {
 	[NL80211_ATTR_MLO_RECONF_REM_LINKS] = { .type = NLA_U16 },
 	[NL80211_ATTR_EPCS] = { .type = NLA_FLAG },
 	[NL80211_ATTR_ASSOC_MLD_EXT_CAPA_OPS] = { .type = NLA_U16 },
+	[NL80211_ATTR_BSS_PARAM] = { .type = NLA_FLAG },
 };
 
 /* policy for the key attributes */
@@ -8265,6 +8266,8 @@ static int nl80211_set_bss(struct sk_buff *skb, struct genl_info *info)
 	struct cfg80211_registered_device *rdev = info->user_ptr[0];
 	struct net_device *dev = info->user_ptr[1];
 	struct bss_parameters params;
+	u32 changed = 0;
+	bool strict;
 
 	memset(&params, 0, sizeof(params));
 	params.link_id = nl80211_link_id_or_invalid(info->attrs);
@@ -8277,26 +8280,38 @@ static int nl80211_set_bss(struct sk_buff *skb, struct genl_info *info)
 	params.p2p_ctwindow = -1;
 	params.p2p_opp_ps = -1;
 
-	if (info->attrs[NL80211_ATTR_BSS_CTS_PROT])
+	strict = nla_get_flag(info->attrs[NL80211_ATTR_BSS_PARAM]);
+	if (info->attrs[NL80211_ATTR_BSS_CTS_PROT]) {
 		params.use_cts_prot =
 		    nla_get_u8(info->attrs[NL80211_ATTR_BSS_CTS_PROT]);
-	if (info->attrs[NL80211_ATTR_BSS_SHORT_PREAMBLE])
+		changed |= WIPHY_BSS_PARAM_CTS_PROT;
+	}
+	if (info->attrs[NL80211_ATTR_BSS_SHORT_PREAMBLE]) {
 		params.use_short_preamble =
 		    nla_get_u8(info->attrs[NL80211_ATTR_BSS_SHORT_PREAMBLE]);
-	if (info->attrs[NL80211_ATTR_BSS_SHORT_SLOT_TIME])
+		changed |= WIPHY_BSS_PARAM_SHORT_PREAMBLE;
+	}
+	if (info->attrs[NL80211_ATTR_BSS_SHORT_SLOT_TIME]) {
 		params.use_short_slot_time =
 		    nla_get_u8(info->attrs[NL80211_ATTR_BSS_SHORT_SLOT_TIME]);
+		changed |= WIPHY_BSS_PARAM_SHORT_SLOT_TIME;
+	}
 	if (info->attrs[NL80211_ATTR_BSS_BASIC_RATES]) {
 		params.basic_rates =
 			nla_data(info->attrs[NL80211_ATTR_BSS_BASIC_RATES]);
 		params.basic_rates_len =
 			nla_len(info->attrs[NL80211_ATTR_BSS_BASIC_RATES]);
+		changed |= WIPHY_BSS_PARAM_BASIC_RATES;
 	}
-	if (info->attrs[NL80211_ATTR_AP_ISOLATE])
+	if (info->attrs[NL80211_ATTR_AP_ISOLATE]) {
 		params.ap_isolate = !!nla_get_u8(info->attrs[NL80211_ATTR_AP_ISOLATE]);
-	if (info->attrs[NL80211_ATTR_BSS_HT_OPMODE])
+		changed |= WIPHY_BSS_PARAM_AP_ISOLATE;
+	}
+	if (info->attrs[NL80211_ATTR_BSS_HT_OPMODE]) {
 		params.ht_opmode =
 			nla_get_u16(info->attrs[NL80211_ATTR_BSS_HT_OPMODE]);
+		changed |= WIPHY_BSS_PARAM_HT_OPMODE;
+	}
 
 	if (info->attrs[NL80211_ATTR_P2P_CTWINDOW]) {
 		if (dev->ieee80211_ptr->iftype != NL80211_IFTYPE_P2P_GO)
@@ -8306,6 +8321,7 @@ static int nl80211_set_bss(struct sk_buff *skb, struct genl_info *info)
 		if (params.p2p_ctwindow != 0 &&
 		    !(rdev->wiphy.features & NL80211_FEATURE_P2P_GO_CTWIN))
 			return -EINVAL;
+		changed |= WIPHY_BSS_PARAM_P2P_CTWINDOW;
 	}
 
 	if (info->attrs[NL80211_ATTR_P2P_OPPPS]) {
@@ -8318,6 +8334,7 @@ static int nl80211_set_bss(struct sk_buff *skb, struct genl_info *info)
 		if (params.p2p_opp_ps &&
 		    !(rdev->wiphy.features & NL80211_FEATURE_P2P_GO_OPPPS))
 			return -EINVAL;
+		changed |= WIPHY_BSS_PARAM_P2P_OPPPS;
 	}
 
 	if (!rdev->ops->change_bss)
@@ -8327,6 +8344,9 @@ static int nl80211_set_bss(struct sk_buff *skb, struct genl_info *info)
 	    dev->ieee80211_ptr->iftype != NL80211_IFTYPE_P2P_GO)
 		return -EOPNOTSUPP;
 
+	if (strict && (changed & ~rdev->wiphy.bss_param_support))
+		return -EINVAL;
+
 	return rdev_change_bss(rdev, dev, &params);
 }
 
-- 
2.43.5