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wifi: cfg80211: Fragment per-link station stats in nl80211_dump_station()
In MLO scenarios, stations may have multiple links, each with distinct statistics. When userspace tools like iw or hostapd request station dumps, attempting to pack all per-link stats into a single netlink message can easily exceed the default 4KB buffer limit, especially when more than two links are active. This results in -EMSGSIZE errors and incomplete data delivery. To address this, fragment per-link station statistics across multiple netlink messages to ensure reliable delivery of complete MLO station information. Extend the stateful context with a two-phase dump mechanism: phase 0 (AGGREGATED) sends combined MLO-level statistics and phase 1 (PER_LINK) sends individual per-link statistics for each active link. The dump loop is structured to produce exactly one netlink message per iteration, with a common header (ifindex, wdev, mac, generation) built once and phase-specific payload added via a switch statement. This keeps header construction in one place and makes the EMSGSIZE bail-out uniform. Add a new request flag attribute, NL80211_ATTR_STA_DUMP_LINK_STATS (NLA_FLAG), for NL80211_CMD_GET_STATION dump. Userspace can set this flag to request per-link station statistics for MLO stations. Extract this flag during the first dump invocation by passing an attrbuf to nl80211_prepare_wdev_dump(); use __free(kfree) to avoid scattered manual kfree() calls. Cache the boolean in the dump context to avoid repeated parsing on subsequent invocations. Per-link messages carry a single NL80211_ATTR_MLO_LINKS nest with the link ID, link-specific MAC, and per-link NL80211_ATTR_STA_INFO payload. The link-specific validity (is_valid_ether_addr) and null pointer guard are checked in nl80211_put_link_station_payload() before any message construction begins. Also fix all nla_nest_start_noflag() calls in nl80211_fill_link_station() for nested attribute types (STA_INFO, BSS_PARAM, TID_STATS, per-tid) to use nla_nest_start() so the NLA_F_NESTED flag is set correctly. Propagate the actual return value from nl80211_put_sta_info_common() in the AGGREGATED phase rather than returning skb->len. Returning skb->len signals netlink to re-invoke the dump with the same sta_idx, causing an infinite loop when the aggregated payload is too large to fit; returning the real error code (-EMSGSIZE or otherwise) terminates the dump cleanly. Backward compatibility is seamlessly preserved for non-MLO stations. Signed-off-by: P Praneesh <praneesh.p@oss.qualcomm.com> Link: https://patch.msgid.link/20260614051739.3979947-5-praneesh.p@oss.qualcomm.com Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
P Praneesh
Johannes Berg
parent
727afb05ef
commit
dd21d1844a
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@ -3168,6 +3168,23 @@ enum nl80211_commands {
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* @NL80211_ATTR_NPCA_PRIMARY_FREQ: NPCA primary channel (u32)
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* @NL80211_ATTR_NPCA_PUNCT_BITMAP: NPCA puncturing bitmap (u32)
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*
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* @NL80211_ATTR_STA_DUMP_LINK_STATS: Request flag for %NL80211_CMD_GET_STATION
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* (dump mode only). When set on an MLD station, the dump produces two
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* %NL80211_CMD_NEW_STATION messages per station per dump call:
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*
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* 1. An aggregated-stats message whose top-level %NL80211_ATTR_STA_INFO
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* contains MLO-combined statistics (same content as a dump without
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* this flag).
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*
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* 2. For each active link, a per-link message containing
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* %NL80211_ATTR_MLO_LINKS with a single link entry. Each entry holds
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* %NL80211_ATTR_MLO_LINK_ID, the link-specific %NL80211_ATTR_MAC,
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* and %NL80211_ATTR_STA_INFO with per-link statistics (see
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* &enum nl80211_sta_info).
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*
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* The aggregated message always precedes the per-link messages for the
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* same station within a dump sequence.
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*
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* @NUM_NL80211_ATTR: total number of nl80211_attrs available
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* @NL80211_ATTR_MAX: highest attribute number currently defined
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* @__NL80211_ATTR_AFTER_LAST: internal use
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@ -3766,6 +3783,8 @@ enum nl80211_attrs {
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NL80211_ATTR_NPCA_PRIMARY_FREQ,
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NL80211_ATTR_NPCA_PUNCT_BITMAP,
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NL80211_ATTR_STA_DUMP_LINK_STATS,
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/* add attributes here, update the policy in nl80211.c */
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__NL80211_ATTR_AFTER_LAST,
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@ -1093,6 +1093,7 @@ static const struct nla_policy nl80211_policy[NUM_NL80211_ATTR] = {
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[NL80211_ATTR_NPCA_PRIMARY_FREQ] = { .type = NLA_U32 },
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[NL80211_ATTR_NPCA_PUNCT_BITMAP] =
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NLA_POLICY_FULL_RANGE(NLA_U32, &nl80211_punct_bitmap_range),
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[NL80211_ATTR_STA_DUMP_LINK_STATS] = { .type = NLA_FLAG },
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};
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/* policy for the key attributes */
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@ -7870,7 +7871,7 @@ static int nl80211_fill_link_station(struct sk_buff *msg,
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goto nla_put_failure; \
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} while (0)
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link_sinfoattr = nla_nest_start_noflag(msg, NL80211_ATTR_STA_INFO);
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link_sinfoattr = nla_nest_start(msg, NL80211_ATTR_STA_INFO);
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if (!link_sinfoattr)
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goto nla_put_failure;
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@ -7936,8 +7937,8 @@ static int nl80211_fill_link_station(struct sk_buff *msg,
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PUT_LINK_SINFO(BEACON_LOSS, beacon_loss_count, u32);
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if (link_sinfo->filled & BIT_ULL(NL80211_STA_INFO_BSS_PARAM)) {
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bss_param = nla_nest_start_noflag(msg,
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NL80211_STA_INFO_BSS_PARAM);
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bss_param = nla_nest_start(msg,
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NL80211_STA_INFO_BSS_PARAM);
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if (!bss_param)
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goto nla_put_failure;
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@ -7979,8 +7980,7 @@ static int nl80211_fill_link_station(struct sk_buff *msg,
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struct nlattr *tidsattr;
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int tid;
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tidsattr = nla_nest_start_noflag(msg,
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NL80211_STA_INFO_TID_STATS);
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tidsattr = nla_nest_start(msg, NL80211_STA_INFO_TID_STATS);
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if (!tidsattr)
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goto nla_put_failure;
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@ -7993,7 +7993,7 @@ static int nl80211_fill_link_station(struct sk_buff *msg,
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if (!tidstats->filled)
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continue;
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tidattr = nla_nest_start_noflag(msg, tid + 1);
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tidattr = nla_nest_start(msg, tid + 1);
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if (!tidattr)
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goto nla_put_failure;
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@ -8464,21 +8464,74 @@ static void cfg80211_sta_set_mld_sinfo(struct station_info *sinfo)
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sinfo->filled &= ~BIT_ULL(NL80211_STA_INFO_CHAIN_SIGNAL_AVG);
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}
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enum nl80211_dump_station_phase {
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NL80211_DUMP_STA_PHASE_AGGREGATED = 0,
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NL80211_DUMP_STA_PHASE_PER_LINK = 1,
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};
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struct nl80211_dump_station_ctx {
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int sta_idx;
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int link_idx;
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enum nl80211_dump_station_phase phase;
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bool dump_link_stats;
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u8 mac_addr[ETH_ALEN];
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struct station_info sinfo;
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};
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static int nl80211_put_link_station_payload(struct sk_buff *msg,
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struct cfg80211_registered_device *rdev,
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struct station_info *sinfo,
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int link_idx)
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{
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struct link_station_info *link_sinfo = sinfo->links[link_idx];
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struct nlattr *links, *link;
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if (WARN_ON_ONCE(!link_sinfo))
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return -ENOENT;
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if (!is_valid_ether_addr(link_sinfo->addr))
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return -EADDRNOTAVAIL;
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links = nla_nest_start(msg, NL80211_ATTR_MLO_LINKS);
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if (!links)
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return -EMSGSIZE;
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link = nla_nest_start(msg, link_idx + 1);
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if (!link)
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goto nla_put_failure;
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if (nla_put_u8(msg, NL80211_ATTR_MLO_LINK_ID, link_idx) ||
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nla_put(msg, NL80211_ATTR_MAC, ETH_ALEN, link_sinfo->addr))
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goto nla_put_failure;
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if (nl80211_fill_link_station(msg, rdev, link_sinfo))
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goto nla_put_failure;
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nla_nest_end(msg, link);
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nla_nest_end(msg, links);
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return 0;
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nla_put_failure:
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nla_nest_cancel(msg, links);
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return -EMSGSIZE;
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}
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static int nl80211_dump_station(struct sk_buff *skb,
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struct netlink_callback *cb)
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{
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struct cfg80211_registered_device *rdev;
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struct wireless_dev *wdev;
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struct nl80211_dump_station_ctx *ctx = (void *)cb->args[2];
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struct nlattr **attrbuf __free(kfree) = NULL;
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int err;
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err = nl80211_prepare_wdev_dump(cb, &rdev, &wdev, NULL);
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if (!ctx) {
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attrbuf = kzalloc_objs(*attrbuf, NUM_NL80211_ATTR);
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if (!attrbuf)
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return -ENOMEM;
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}
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err = nl80211_prepare_wdev_dump(cb, &rdev, &wdev, attrbuf);
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if (err)
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return err;
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/* nl80211_prepare_wdev_dump acquired it in the successful case */
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@ -8490,6 +8543,9 @@ static int nl80211_dump_station(struct sk_buff *skb,
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err = -ENOMEM;
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goto out_err;
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}
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ctx->phase = NL80211_DUMP_STA_PHASE_AGGREGATED;
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ctx->dump_link_stats =
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!!attrbuf[NL80211_ATTR_STA_DUMP_LINK_STATS];
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cb->args[2] = (long)ctx;
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}
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@ -8505,34 +8561,53 @@ static int nl80211_dump_station(struct sk_buff *skb,
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while (true) {
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void *hdr;
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int ret;
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memset(&ctx->sinfo, 0, sizeof(ctx->sinfo));
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for (int i = 0; i < IEEE80211_MLD_MAX_NUM_LINKS; i++) {
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ctx->sinfo.links[i] =
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kzalloc_obj(*ctx->sinfo.links[0]);
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if (!ctx->sinfo.links[i]) {
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err = -ENOMEM;
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/* AGGREGATED phase: fetch sinfo from driver once per station */
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if (ctx->phase == NL80211_DUMP_STA_PHASE_AGGREGATED) {
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memset(&ctx->sinfo, 0, sizeof(ctx->sinfo));
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for (int i = 0; i < IEEE80211_MLD_MAX_NUM_LINKS; i++) {
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ctx->sinfo.links[i] =
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kzalloc_obj(*ctx->sinfo.links[0]);
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if (!ctx->sinfo.links[i]) {
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err = -ENOMEM;
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goto out_err_release;
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}
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}
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err = rdev_dump_station(rdev, wdev, ctx->sta_idx,
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ctx->mac_addr, &ctx->sinfo);
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if (err == -ENOENT) {
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err = skb->len;
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goto out_err_release;
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}
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if (err)
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goto out_err_release;
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if (ctx->sinfo.valid_links)
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cfg80211_sta_set_mld_sinfo(&ctx->sinfo);
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} else {
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/* PER_LINK phase: advance to next valid link */
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while (ctx->link_idx < IEEE80211_MLD_MAX_NUM_LINKS &&
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!(ctx->sinfo.valid_links & BIT(ctx->link_idx)))
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ctx->link_idx++;
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if (ctx->link_idx >= IEEE80211_MLD_MAX_NUM_LINKS) {
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cfg80211_sinfo_release_content(&ctx->sinfo);
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ctx->sta_idx++;
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ctx->phase = NL80211_DUMP_STA_PHASE_AGGREGATED;
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continue;
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}
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}
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err = rdev_dump_station(rdev, wdev, ctx->sta_idx,
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ctx->mac_addr, &ctx->sinfo);
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if (err == -ENOENT) {
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err = skb->len;
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goto out_err_release;
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}
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if (err)
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goto out_err_release;
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if (ctx->sinfo.valid_links)
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cfg80211_sta_set_mld_sinfo(&ctx->sinfo);
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/* Build common header for both phases */
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hdr = nl80211hdr_put(skb, NETLINK_CB(cb->skb).portid,
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cb->nlh->nlmsg_seq, NLM_F_MULTI,
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NL80211_CMD_NEW_STATION);
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if (!hdr) {
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err = skb->len;
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if (ctx->phase == NL80211_DUMP_STA_PHASE_PER_LINK)
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goto out_err;
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goto out_err_release;
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}
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@ -8546,18 +8621,49 @@ static int nl80211_dump_station(struct sk_buff *skb,
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ctx->sinfo.generation)) {
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genlmsg_cancel(skb, hdr);
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err = skb->len;
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if (ctx->phase == NL80211_DUMP_STA_PHASE_PER_LINK)
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goto out_err;
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goto out_err_release;
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}
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if (nl80211_put_sta_info_common(skb, rdev, &ctx->sinfo)) {
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genlmsg_cancel(skb, hdr);
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err = skb->len;
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goto out_err_release;
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}
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switch (ctx->phase) {
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case NL80211_DUMP_STA_PHASE_AGGREGATED:
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ret = nl80211_put_sta_info_common(skb, rdev, &ctx->sinfo);
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if (ret) {
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genlmsg_cancel(skb, hdr);
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err = ret;
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goto out_err_release;
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}
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genlmsg_end(skb, hdr);
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genlmsg_end(skb, hdr);
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cfg80211_sinfo_release_content(&ctx->sinfo);
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ctx->sta_idx++;
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if (ctx->dump_link_stats && ctx->sinfo.valid_links) {
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ctx->phase = NL80211_DUMP_STA_PHASE_PER_LINK;
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ctx->link_idx = 0;
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} else {
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cfg80211_sinfo_release_content(&ctx->sinfo);
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ctx->sta_idx++;
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}
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break;
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case NL80211_DUMP_STA_PHASE_PER_LINK:
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ret = nl80211_put_link_station_payload(skb, rdev,
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&ctx->sinfo,
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ctx->link_idx);
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if (ret == -EMSGSIZE) {
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genlmsg_cancel(skb, hdr);
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err = skb->len;
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goto out_err;
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}
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if (ret) {
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/* skip invalid link, do not abort the dump */
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genlmsg_cancel(skb, hdr);
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ctx->link_idx++;
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continue;
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}
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genlmsg_end(skb, hdr);
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ctx->link_idx++;
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break;
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}
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}
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out_err_release:
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