ruvnet/RuView · error

veil: genl_ctrl_resolve(nl80211) failed: %d\n

Error message

veil: genl_ctrl_resolve(nl80211) failed: %d\n

What it means

`genl_ctrl_resolve` queries the generic netlink controller for the numeric family id of "nl80211". A negative return (printed as `%d`) means the family is not registered: almost always no cfg80211-based wifi driver is loaded, or the kernel lacks nl80211. Without the family id the daemon can neither listen for MLME events nor send commands, so bring-up aborts.

Source

Thrown at firmware/privshield/openwrt/veil_shieldd.c:80

static void on_signal(int sig) { (void)sig; g_ctx.running = 0; }

/* ---------------------------------------------------------------------- */
/* nl80211 bring-up — all REAL libnl-genl-3 API names.                     */
/* ---------------------------------------------------------------------- */
static int veil_nl_connect(struct veil_ctx *c) {
    c->sock = nl_socket_alloc();
    if (!c->sock) {
        fprintf(stderr, "veil: nl_socket_alloc failed\n");
        return -ENOMEM;
    }
    if (genl_connect(c->sock)) {
        fprintf(stderr, "veil: genl_connect failed\n");
        return -EIO;
    }
    c->family = genl_ctrl_resolve(c->sock, "nl80211");
    if (c->family < 0) {
        fprintf(stderr, "veil: genl_ctrl_resolve(nl80211) failed: %d\n",
                c->family);
        return c->family;
    }
    /* Observe MLME events (auth/assoc, and — where the driver forwards them —
     * action-frame notifications). Real multicast group name is "mlme". */
    int grp = genl_ctrl_resolve_grp(c->sock, "nl80211", "mlme");
    if (grp >= 0) {
        (void)nl_socket_add_membership(c->sock, grp);
    }
    return 0;
}

/* ---------------------------------------------------------------------- */
/* CONTROL 1 (FEASIBLE): TX antenna-map perturbation.                      */
/* Rotating the allowed TX antenna bitmap changes the static spatial       */
/* mapping the PHY uses, coarsely perturbing the CSI a sensor observes.    */
/* This is a genuinely userspace-reachable, compliant knob.                */
/*   NL80211_CMD_SET_WIPHY + NL80211_ATTR_WIPHY_ANTENNA_TX / _RX           */

View on GitHub (pinned to 4685618388)

Solutions

  1. Load/enable the wifi driver and verify: `iw dev` should list an interface and `genl-ctrl-list | grep nl80211` should resolve.
  2. In a VM, pass through a USB dongle backed by a cfg80211 driver, or run directly on the router.
  3. For custom kernels, enable CONFIG_CFG80211, CONFIG_NL80211, and the radio's mac80211/mt76/ath driver, then rebuild.

Example fix

# before
veil_shieldd -i 2                     # veil: genl_ctrl_resolve(nl80211) failed: -24
# after
opkg install kmod-mt76-core kmod-mt76-usb   # driver for the actual radio
iw dev && veil_shieldd -i 2
Defensive patterns

Strategy: validation

Validate before calling

#!/bin/sh
# pre-flight: nl80211 family must be registered
iw list >/dev/null 2>&1 || { echo "no cfg80211/nl80211 driver loaded"; exit 1; }
IFIDX=$(cat /sys/class/net/wlan0/ifindex)
exec veil_shieldd -i "$IFIDX"

Try / catch

if (g_ctx.family < 0) {
    /* nl80211 not registered: load the radio driver or fix the kernel */
    fprintf(stderr, "veil: load a cfg80211 driver (kmod-mt76/ath) before starting\n");
    return g_ctx.family;
}

Prevention

When it happens

Trigger: Running on a host with no wifi driver loaded (`lsmod | grep cfg80211` empty); radio failed to probe at boot (wrong DTS/board data); VM or container without wifi passthrough; custom kernel missing CONFIG_CFG80211/CONFIG_NL80211.

Common situations: Developing/testing the daemon on a laptop or VM with no wireless card; driver crash unloading cfg80211; firmware packages (mt76-*) missing or kernel-mismatched on the router.

Related errors

AI-assisted analysis of ruvnet/RuView@4685618388 (2026-08-16). Data as JSON: /api/errors/a0a68c3c74ccce7c. Report an issue: GitHub.