The branch stable/14 has been updated by bz:
URL:
https://cgit.FreeBSD.org/src/commit/?id=0a2e5ab96a7da51690f38d962305214e2973989d
commit 0a2e5ab96a7da51690f38d962305214e2973989d
Author: Bjoern A. Zeeb <b...@freebsd.org>
AuthorDate: 2025-05-24 17:01:59 +0000
Commit: Bjoern A. Zeeb <b...@freebsd.org>
CommitDate: 2025-06-04 22:23:30 +0000
net80211: make sure to not start a BGSCAN if not enabled
On drivers not supporting background scanning (not having announced
IEEE80211_C_BGSCAN) we repeatedly have seen scanning issues and
BGSCAN was "on" according to, e.g., ddb show com /a.
Turns out there are multiple problems:
(a) the ioctl scanreq code can pass IEEE80211_[IOC_]SCAN_BGSCAN in
(ifconfig wlanX scan will do so by default). That flag ends up
on flags in the scanning code which have no other checks, and
we are doing a BGSCAN.
So make sure BGSCAN is announced by the driver and enabled
(and it's STA mode for the full check) or filter the BGSCAN out.
(b) ieee80211_bg_scan() never checked if background scanning was
available/enabled. Do so now.
(c) ieee80211_swscan_start_scan_locked() as a consequence of (a) would
start the BGSCAN unconditionally. Also check for BGSCAN to be
available/enabled here.
Lastly, we should no longer reach ieee80211_swscan_bg_scan() without
background scanning being available/enabled, so document that fact
by placing a KASSERT. That will also help in case future changes
will open a new hole or there are further which I have not noticed.
Sponsored by: The FreeBSD Foundation
Reviewed by: adrian
Differential Revision: https://reviews.freebsd.org/D50513
(cherry picked from commit 32af70fae827ecab34e995b49ea7656ea6e70608)
---
sys/net80211/ieee80211_ioctl.c | 12 ++++++++++++
sys/net80211/ieee80211_scan.c | 13 +++++++++++++
sys/net80211/ieee80211_scan_sw.c | 8 +++++++-
3 files changed, 32 insertions(+), 1 deletion(-)
diff --git a/sys/net80211/ieee80211_ioctl.c b/sys/net80211/ieee80211_ioctl.c
index 7447e3a05ed3..63f61ede1d7a 100644
--- a/sys/net80211/ieee80211_ioctl.c
+++ b/sys/net80211/ieee80211_ioctl.c
@@ -2600,6 +2600,18 @@ ieee80211_scanreq(struct ieee80211vap *vap, struct
ieee80211_scan_req *sr)
return EINVAL;
/* cleanse flags just in case, could reject if invalid flags */
sr->sr_flags &= IEEE80211_IOC_SCAN_FLAGS;
+
+ /*
+ * If the driver does not support BGSCAN, or BGSCAN is disabled
+ * do not allow the IEEE80211_SCAN_BGSCAN flag to go through
+ * to avoid accidentally enabling BGSCANs.
+ * Also if not STA mode [see ieee80211_vap_setup()].
+ */
+ if ((vap->iv_caps & IEEE80211_C_BGSCAN) == 0 ||
+ (vap->iv_flags & IEEE80211_F_BGSCAN) == 0 ||
+ vap->iv_opmode != IEEE80211_M_STA)
+ sr->sr_flags &= ~IEEE80211_IOC_SCAN_BGSCAN;
+
/*
* Add an implicit NOPICK if the vap is not marked UP. This
* allows applications to scan without joining a bss (or picking
diff --git a/sys/net80211/ieee80211_scan.c b/sys/net80211/ieee80211_scan.c
index 04fee33f48f1..e5bd8d76b260 100644
--- a/sys/net80211/ieee80211_scan.c
+++ b/sys/net80211/ieee80211_scan.c
@@ -428,6 +428,19 @@ ieee80211_bg_scan(struct ieee80211vap *vap, int flags)
// IEEE80211_UNLOCK_ASSERT(sc);
+ /*
+ * If the driver has not announced BGSCAN capabilities
+ * or BGSCAN is disabled do not attempt to start a bg_scan.
+ * IEEE80211_F_BGSCAN only gets set if IEEE80211_C_BGSCAN
+ * was set by the driver, so no need to check for both here.
+ */
+ if ((vap->iv_flags & IEEE80211_F_BGSCAN) == 0) {
+ IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
+ "%s: BGSCAN not enabled; not starting bg_scan\n",
+ __func__);
+ return (0);
+ }
+
scan = ieee80211_scanner_get(vap->iv_opmode);
if (scan == NULL) {
IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
diff --git a/sys/net80211/ieee80211_scan_sw.c b/sys/net80211/ieee80211_scan_sw.c
index e1d6b2779cf0..c85bdcd5f78b 100644
--- a/sys/net80211/ieee80211_scan_sw.c
+++ b/sys/net80211/ieee80211_scan_sw.c
@@ -201,7 +201,9 @@ ieee80211_swscan_start_scan_locked(const struct
ieee80211_scanner *scan,
vap->iv_stats.is_scan_passive++;
if (flags & IEEE80211_SCAN_FLUSH)
ss->ss_ops->scan_flush(ss);
- if (flags & IEEE80211_SCAN_BGSCAN)
+ /* Only BGSCAN if enabled and requested. */
+ if ((vap->iv_flags & IEEE80211_F_BGSCAN) != 0 &&
+ (flags & IEEE80211_SCAN_BGSCAN) != 0)
ic->ic_flags_ext |= IEEE80211_FEXT_BGSCAN;
/* Set duration for this particular scan */
@@ -339,6 +341,10 @@ ieee80211_swscan_bg_scan(const struct ieee80211_scanner
*scan,
// IEEE80211_UNLOCK_ASSERT(ic);
IEEE80211_LOCK(ic);
+ KASSERT((vap->iv_flags & IEEE80211_F_BGSCAN) != 0,
+ ("%s: vap %p iv_flags %#010x no IEEE80211_F_BGSCAN set",
+ __func__, vap, vap->iv_flags));
+
scanning = ic->ic_flags & IEEE80211_F_SCAN;
if (!scanning) {
u_int duration;
