[PATCH v3 0/4] wifi: add opt-in FIPS exception for iwlwifi

[PATCH v3 0/4] wifi: add opt-in FIPS exception for iwlwifi

[Jose Ignacio Tornos Martinez]

Commits 5241526dede9 ("wifi: mac80211: don't send keys
to driver when fips_enabled") and 0636800c8ee1 ("wifi:
iwlwifi: disable certain features for fips_enabled")
disabled WiFi functionality under FIPS mode because
Intel firmware autonomously sends some management
frames without FIPS-validated integrity protection.

While this is technically correct, it leaves
FIPS-required environments with no WiFi connectivity
at all, since WPA3-SAE mandates MFP and without
MFP_CAPABLE the client cannot even associate.

This series introduces an opt-in fips_exception=<bitmap>
kernel boot parameter that allows administrators who
understand the firmware limitation to explicitly choose
connectivity over strict compliance. No keys are
installed in firmware; mac80211 handles all data
encryption/decryption in software using FIPS-approved
algorithms. The default behavior remains exactly as the
original commits implemented.

This is a provisional v3 to show the current working
state and continue the conversation from [1]. Changes
and pending items are based on Johannes's very helpful
guidance.

With fips=1 fips_exception=1 on Intel AX211, this
series enables:
- MFP (802.11w) with software crypto in mac80211
- RX AMPDU aggregation
- Bidirectional data with no keys in firmware

Known limitation:
- No TX A-MPDU aggregation. Firmware sends ADDBA
  unprotected, AP drops it (MFP). Host-driven ADDBA
  from mac80211 can work at the protocol level but
  TLC does not aggregate. Details in [1].

Pending for later versions:
- IGTK/BIGTK offload to firmware
- 6 GHz / EHT dependencies
- TX aggregation (if possible)

Test setup:
  AP: WPA2-PSK ieee80211w=2, channel 52 80MHz HE
  STA: Intel AX211, fips=1 fips_exception=1
  RX: ~450 Mbps (iperf3)
  TX: ~26 Mbps (iperf3, no A-MPDU)

[1] https://lore.kernel.org/all/20261009064326.43891-1-jtornosm@redhat.com/

v3: Address comments from Johannes:
    - Drop PTK/GTK offload to firmware, software-only
      crypto
    - Drop A-MSDU size restoration
    - Drop set_rekey_offload
    Per patch:
    - 1/4: same as v2 1/5 but fips_allows() renamed to
      fips_allows_exception() with more suitable semantics
    - 2/4: v2 2/5 (key gate), v2 3/5 (feature restore)
      and v2 4/5 (SW_MGMT_TX) dropped, replaced by only
      enabling MFP_CAPABLE
    - 3/4: new, RX AMPDU and A-MSDU fixes for SW crypto
      path
    - 4/4: same as v2 5/5
v2: https://lore.kernel.org/all/20260930120829.383408-1-jtornosm@redhat.com/

Jose Ignacio Tornos Martinez (4):
  crypto: fips: add fips_exception kernel boot parameter
    and fips_allows_exception() helper
  wifi: iwlwifi: enable MFP_CAPABLE in FIPS mode
  wifi: iwlwifi: fix RX AMPDU and A-MSDU in FIPS mode
  wifi: iwlwifi: reduce encryption error message to
    debug level in FIPS mode

[PATCH v3 1/4] crypto: fips: add fips_exception kernel boot parameter and fips_allows_exception() helper

[Jose Ignacio Tornos Martinez]

Add a new kernel boot parameter fips_exception=<bitmap> to allow
documented exceptions to strict FIPS compliance when full compliance
is not achievable due to hardware/firmware limitations but
functionality is required.

The parameter is stored in a static variable and accessed through the
exported fips_allows_exception() helper function, which returns true
when FIPS is enabled and the requested exception bit is set. This
makes fips_allows_exception() an explicit "is this FIPS exception
active?" check, only meaningful when FIPS mode is on.

For !CONFIG_CRYPTO_FIPS, fips_allows_exception() is a trivial static
inline returning false (no FIPS means no FIPS exceptions).

The parameter is exposed as a read-only sysctl at
/proc/sys/crypto/fips_exception for runtime inspection. As with
fips_enabled, it is intentionally not writable at runtime so that
enabling exceptions requires a deliberate boot-time decision,
visible in /proc/cmdline.

The bitmap design allows individual subsystem exceptions to be
defined independently. Currently defined bits:
  - Bit 0 (FIPS_EXCEPTION_WIFI_MFP): Allow WiFi MFP (802.11w)
    in FIPS mode despite firmware sending some unprotected
    management frames on TX

Without this parameter (or with fips_exception=0), all existing
FIPS restrictions remain in effect.

Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>
---
v3: rename fips_allows() to fips_allows_exception(), change semantics
    to fips_enabled && exception (was !fips_enabled || exception)
v2: https://lore.kernel.org/all/20260930120829.383408-2-jtornosm@redhat.com/

 crypto/fips.c        | 27 +++++++++++++++++++++++++++
 include/linux/fips.h | 14 ++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/crypto/fips.c b/crypto/fips.c
index c59711248d95..0f075e61a657 100644
--- a/crypto/fips.c
+++ b/crypto/fips.c
@@ -21,6 +21,15 @@ EXPORT_SYMBOL_GPL(fips_enabled);
 ATOMIC_NOTIFIER_HEAD(fips_fail_notif_chain);
 EXPORT_SYMBOL_GPL(fips_fail_notif_chain);
 
+static unsigned long fips_exception;
+
+int fips_allows_exception(unsigned long feature)
+{
+	return fips_enabled &&
+	       (fips_exception & feature);
+}
+EXPORT_SYMBOL_GPL(fips_allows_exception);
+
 /* Process kernel command-line parameter at boot time. fips=0 or fips=1 */
 static int __init fips_enable(char *str)
 {
@@ -34,6 +43,17 @@ static int __init fips_enable(char *str)
 
 __setup("fips=", fips_enable);
 
+static int __init fips_exception_setup(char *str)
+{
+	if (kstrtoul(str, 0, &fips_exception))
+		return 0;
+
+	pr_info("fips exceptions: 0x%lx\n", fips_exception);
+	return 1;
+}
+
+__setup("fips_exception=", fips_exception_setup);
+
 #define FIPS_MODULE_NAME CONFIG_CRYPTO_FIPS_NAME
 #ifdef CONFIG_CRYPTO_FIPS_CUSTOM_VERSION
 #define FIPS_MODULE_VERSION CONFIG_CRYPTO_FIPS_VERSION
@@ -52,6 +72,13 @@ static const struct ctl_table crypto_sysctl_table[] = {
 		.mode		= 0444,
 		.proc_handler	= proc_dointvec
 	},
+	{
+		.procname	= "fips_exception",
+		.data		= &fips_exception,
+		.maxlen		= sizeof(unsigned long),
+		.mode		= 0444,
+		.proc_handler	= proc_doulongvec_minmax
+	},
 	{
 		.procname	= "fips_name",
 		.data		= &fips_name,
diff --git a/include/linux/fips.h b/include/linux/fips.h
index c6961e932fef..61fe58b0762c 100644
--- a/include/linux/fips.h
+++ b/include/linux/fips.h
@@ -2,17 +2,31 @@
 #ifndef _FIPS_H
 #define _FIPS_H
 
+#include <linux/bits.h>
+
 #ifdef CONFIG_CRYPTO_FIPS
 extern int fips_enabled;
 extern struct atomic_notifier_head fips_fail_notif_chain;
 
 void fips_fail_notify(void);
+/*
+ * fips_allows_exception - check if a FIPS exception is active
+ * Returns true when FIPS is enabled and the requested exception
+ * bit is set via the fips_exception= boot parameter.
+ */
+int fips_allows_exception(unsigned long feature);
 
 #else
 #define fips_enabled 0
 
 static inline void fips_fail_notify(void) {}
+static inline int fips_allows_exception(unsigned long feature)
+{
+	return 0;
+}
 
 #endif
 
+#define FIPS_EXCEPTION_WIFI_MFP	BIT(0)
+
 #endif
-- 
2.55.0

[PATCH v3 2/4] wifi: iwlwifi: enable MFP_CAPABLE in FIPS mode

[Jose Ignacio Tornos Martinez]

Re-enable MFP_CAPABLE flag in FIPS mode for iwlwifi to allow Management
Frame Protection (802.11w) to work with mac80211 software crypto.

Commit 0636800c8ee1f ("wifi: iwlwifi: disable certain features for
fips_enabled") disabled MFP_CAPABLE when fips_enabled=1.
The original concern about "some frames need to be handled in
firmware" applies to firmware-offloaded features like WoWLAN and beacon
protection, which remain correctly disabled by the commented commit.
For normal STA mode operation, management frames are processed in
software. And MFP can function in FIPS mode for normal STA operation
when mac80211 software crypto handles IGTK encryption/decryption using
FIPS-approved AES-CMAC/GMAC algorithms.

Other major WiFi drivers (ath11k, rtlwifi, mt76, ...) set MFP_CAPABLE
unconditionally, suggesting this approach is viable for FIPS mode
operation with software crypto.

When FIPS_EXCEPTION_WIFI_MFP is set via the fips_exception boot
parameter, use fips_allows_exception() to restore MFP_CAPABLE.
Without fips_exception set, the behavior remains exactly as commit
0636800c8ee1 implemented.

Testing on Intel WiFi 6E AX210 with fips=1 fips_exception=1 shows:
- IGTK ciphers (CMAC, GMAC-128, GMAC-256) are properly advertised
- WPA3-SAE connections with MFP required succeed
- iw station dump confirms "MFP: yes"

Firmware logs "Unhandled alg: 0x707" (SEC_ENC_ERR) during operation,
confirming that firmware does not have the keys and frames are being
handled by software crypto as expected.

Fixes: 0636800c8ee1f ("wifi: iwlwifi: disable certain features for fips_enabled")
Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>
---
v3: reuse v1 1/2 idea plus fips_allows_exception() helper from patch 1/4
v2: https://lore.kernel.org/all/20260930120829.383408-1-jtornosm@redhat.com/
v1: https://lore.kernel.org/all/20260629121213.597038-2-jtornosm@redhat.com/

 drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c b/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c
index 5bd246e37943..144a19a4015c 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c
@@ -462,7 +462,7 @@ int iwl_mvm_mac_setup_register(struct iwl_mvm *mvm)
 		IWL_ERR(mvm,
 			"iwlmvm doesn't allow to disable BT Coex, check bt_coex_active module parameter\n");

-	if (!fips_enabled)
+	if (!fips_enabled || fips_allows_exception(FIPS_EXCEPTION_WIFI_MFP))
 		ieee80211_hw_set(hw, MFP_CAPABLE);

 	mvm->ciphers[hw->wiphy->n_cipher_suites] = WLAN_CIPHER_SUITE_AES_CMAC;
--
2.49.0

[PATCH v3 3/4] wifi: iwlwifi: fix RX AMPDU and A-MSDU in FIPS mode

[Jose Ignacio Tornos Martinez]

In FIPS mode with the WiFi MFP exception active, firmware has no
encryption keys installed (mac80211 handles all crypto in software).
This causes two RX-path issues that severely limit downlink
throughput:

1) Firmware reports SEC_UNKNOWN for all received data frames because
   it has no keys to decrypt them. iwl_mvm_rx_crypto() drops these
   frames when they arrive inside an AMPDU, mistaking them for a
   security error. In FIPS SW-crypto mode this is expected -- the
   frames are encrypted and will be decrypted by mac80211. Skip
   the drop when the FIPS exception is active, same as already done
   for monitor mode.

2) Firmware clears the A-MSDU present bit in the QoS header for
   frames it processes. When firmware has no keys, it still strips
   this bit even though it cannot de-aggregate the A-MSDU. mac80211
   then treats the A-MSDU as a regular MSDU, delivering a malformed
   frame. Preserve the A-MSDU bit when the FIPS exception is active
   so mac80211 can properly de-aggregate after SW decryption.

Without these fixes (in my scenario), RX throughput is limited to
non-aggregated rates (~25 Mbps). With both fixes, RX AMPDU works
normally and throughput reaches ~450 Mbps.

Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>
---
v3: new
v2: https://lore.kernel.org/all/20260930120829.383408-1-jtornosm@redhat.com/

 drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c b/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
index 7f0b4f5daa21..1ebca0323a89 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
@@ -5,6 +5,7 @@
  * Copyright (C) 2015-2017 Intel Deutschland GmbH
  */
 #include <linux/etherdevice.h>
+#include <linux/fips.h>
 #include <linux/skbuff.h>
 #include "iwl-trans.h"
 #include "mvm.h"
@@ -421,14 +422,15 @@ static int iwl_mvm_rx_crypto(struct iwl_mvm *mvm, struct ieee80211_sta *sta,
 
 	/*
 	 * Drop UNKNOWN frames in aggregation, unless in monitor mode
-	 * (where we don't have the keys).
+	 * (where we don't have the keys) or FIPS SW-crypto mode.
 	 * We limit this to aggregation because in TKIP this is a valid
 	 * scenario, since we may not have the (correct) TTAK (phase 1
 	 * key) in the firmware.
 	 */
 	if (phy_info & IWL_RX_MPDU_PHY_AMPDU &&
 	    (status & IWL_RX_MPDU_STATUS_SEC_MASK) ==
-	    IWL_RX_MPDU_STATUS_SEC_UNKNOWN && !mvm->monitor_on) {
+	    IWL_RX_MPDU_STATUS_SEC_UNKNOWN && !mvm->monitor_on &&
+	    !fips_allows_exception(FIPS_EXCEPTION_WIFI_MFP)) {
 		IWL_DEBUG_DROP(mvm, "Dropping packets, bad enc status\n");
 		return -1;
 	}
@@ -2357,7 +2359,8 @@ void iwl_mvm_rx_mpdu_mq(struct iwl_mvm *mvm, struct napi_struct *napi,
 		    !WARN_ON(!ieee80211_is_data_qos(hdr->frame_control))) {
 			u8 *qc = ieee80211_get_qos_ctl(hdr);
 
-			*qc &= ~IEEE80211_QOS_CTL_A_MSDU_PRESENT;
+			if (!fips_allows_exception(FIPS_EXCEPTION_WIFI_MFP))
+				*qc &= ~IEEE80211_QOS_CTL_A_MSDU_PRESENT;
 
 			if (mvm->trans->mac_cfg->device_family ==
 			    IWL_DEVICE_FAMILY_9000) {
-- 
2.55.0

[PATCH v3 4/4] wifi: iwlwifi: reduce encryption error message to debug level in FIPS mode

[Jose Ignacio Tornos Martinez]

In FIPS mode, the firmware may report
RX_MPDU_RES_STATUS_SEC_ENC_ERR (0x707) for frames received
before keys are installed. This triggers the warning:
  "iwlwifi: Unhandled alg: 0x707"

This is expected behavior -- mac80211 software crypto handles
decryption on the host CPU. Reduce the message from IWL_WARN to
IWL_DEBUG_RX in FIPS mode to avoid false-positive warnings
during normal operation, while preserving warnings for actual
unexpected conditions.

Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>
---
v3: No modification
v2: https://lore.kernel.org/all/20260930120829.383408-6-jtornosm@redhat.com/

 drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c b/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
index 1ebca0323a89..e59876b7a1fa 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
@@ -496,6 +496,14 @@ static int iwl_mvm_rx_crypto(struct iwl_mvm *mvm, struct ieee80211_sta *sta,
 		return 0;
 	case RX_MPDU_RES_STATUS_SEC_CMAC_GMAC_ENC:
 		break;
+	case RX_MPDU_RES_STATUS_SEC_ENC_ERR:
+		if (fips_enabled) {
+			IWL_DEBUG_RX(mvm,
+				     "FIPS mode: firmware cannot decrypt, status: 0x%x\n",
+				     status);
+			break;
+		}
+		fallthrough;
 	default:
 		/*
 		 * Sometimes we can get frames that were not decrypted
-- 
2.55.0