soc: apple: sep: preserve J613 26.6.2 existing-state policy and expose selected policy

Documentation/ABI/testing/sysfs-driver-apple-sep

@@ -3,9 +3,10 @@ Date:		October 2026
 KernelVersion:	7.1
 Contact:	Chris Kearney <chris@kearneymail.com>
 Description:
-		(RO) Version of the diag interface: "2" for the attributes
+		(RO) Version of the diag interface: "3" for the attributes
 		and values described in this file. Version 2 added
-		sensor_attach and restore; version 1 had neither.
+		sensor_attach and restore; version 1 had neither. Version 3
+		adds the policy snapshot.
 
 		Within a version, attributes are only added, and an existing
 		attribute keeps its values and their meaning. A reader tests
@@ -19,7 +20,8 @@ Description:
 		bring-up got without reading the kernel log. It exists while
 		the driver is bound to the SEP: it is created at probe and
 		removed at unbind. Every attribute in it is read-only and
-		reads as one ASCII token followed by a newline.
+		reads as ASCII followed by a newline. The policy snapshot
+		contains space-separated key=value tokens.
 
 		Each value is the state the driver recorded when it made the
 		corresponding decision. Reading an attribute sends nothing
@@ -30,6 +32,26 @@ Description:
 		by the boot-time bring-up, so the sensor and touchid
 		attributes only move on once something has opened it.
 
+		This deployment uses the existing T8122 profile and v4
+		/dev/sep-bio interface. It does not add a new sensor protocol.
+		OS firmware and system firmware are separate: qualify both.
+
+		For an existing bag, select xart_writes=1, provision_keybag=0,
+		xart_guard=1 and xarm_trace=1. trusted_keys=0 and
+		filevault_api=0 omit the optional kernel APIs; both default
+		to 1 to preserve existing deployments. There is no boot_uuid
+		parameter: the OS identity comes from /chosen/apfs-preboot-uuid.
+		Writable J613 26.6.2 attachment rejects a missing DT identity,
+		explicit UUID override or disabled guard before opening xART.
+		Host-store or identity-index read failure refuses attachment.
+
+		Preserve the current keybag, host store, reference key, three
+		Catacombs, ownership journal and fprint records. Different
+		Linux roots must share the same current files globally, before
+		module load; the kernel opens them from init_task's root.
+		Never replace them with a snapshot or enrol again to migrate.
+		Readiness diagnostics do not prove a successful finger match.
+
 What:		/sys/bus/platform/devices/<unit>.sep/diag/profile
 Date:		October 2026
 KernelVersion:	7.1
@@ -364,3 +386,24 @@ Description:
 		tools/aurora-sep/XART-SAFETY.md. During a boot the value
 		can only move from "unverified" to "blocked", once the guard
 		refuses a write.
+
+What:		/sys/bus/platform/devices/<unit>.sep/diag/policy
+Date:		November 2026
+KernelVersion:	7.2
+Contact:	Satya Benson <satya@benson.earth>
+Description:
+		(RO, ABI 3) A space-separated key=value snapshot of the
+		driver policy selected at probe: xart_writes (effective store
+		writability), provision_keybag, xart_guard (effective level),
+		trusted_keys, filevault_api, xarm_trace, refkey_v2 and
+		identity_override (0 or 1). API flags describe the selected
+		policy, not successful registration if that API later fails.
+
+		identity_source is pending before the driver selects it, dt
+		for /chosen/apfs-preboot-uuid, override for explicit parameters,
+		or missing. It is updated at the actual identity decision.
+		No UUID value, state, identity or key bytes are exposed.
+		Reads only use cached facts and never contact the enclave.
+		Module-parameter sysfs files need not exist; their absence
+		is not evidence of a mismatched policy. Older diagnostic
+		ABIs retain xart/xart_guard and kernel decision messages.

drivers/soc/apple/bio.rs

@@ -1,3 +1,3 @@
 // SPDX-License-Identifier: GPL-2.0-only OR MIT
 // Copyright 2026 Dj
 
@@ -279,22 +279,19 @@
         let Some(raw) = store.read(&identity_key())? else {
             return Ok(index);
         };
-        if raw.len() < 4 {
-            return Ok(index);
+        if raw.len() < 8 {
+            return Err(EINVAL);
         }
         if u32::from_le_bytes([raw[0], raw[1], raw[2], raw[3]]) != INDEX_FORMAT {
             return Err(EINVAL);
         }
-        if raw.len() < 8 {
-            return Ok(index);
-        }
         let count = u32::from_le_bytes([raw[4], raw[5], raw[6], raw[7]]) as usize;
         let stride = UUID_LEN + LABEL_LEN;
-        for i in 0..count.min(MAX_IDENTITIES) {
+        if count > MAX_IDENTITIES || raw.len() != 8 + count * stride {
+            return Err(EINVAL);
+        }
+        for i in 0..count {
             let at = 8 + i * stride;
-            if at + stride > raw.len() {
-                break;
-            }
             let mut entry = Identity::ZERO;
             entry.uuid.copy_from_slice(&raw[at..at + UUID_LEN]);
             entry

drivers/soc/apple/catacomb.rs

@@ -1,3 +1,3 @@
 // SPDX-License-Identifier: GPL-2.0-only OR MIT
 // Copyright 2026 Dj
 
@@ -46,28 +46,45 @@
     file.sync()
 }
 
-pub(crate) fn read(kind: u8) -> Option<KVec<u8>> {
-    let path = path_for(kind)?;
-    let file = shim::StoreFile::open_readonly(path).ok()?;
-    let size = file.size().ok()?;
+/// `Ok(None)` only when the file is missing. A file that exists but cannot be
+/// read or fails validation is an error: "cannot tell" must never read as
+/// "nothing saved", or a caller may select a fresh context over a saved one.
+pub(crate) fn read(kind: u8) -> Result<Option<KVec<u8>>> {
+    let path = path_for(kind).ok_or(EINVAL)?;
+    let file = match shim::StoreFile::open_readonly(path) {
+        Ok(file) => file,
+        Err(e) if e == ENOENT => return Ok(None),
+        Err(e) => return Err(e),
+    };
+    let size = file.size()?;
     if size < HEADER as u64 {
-        return None;
+        return Err(EINVAL);
     }
     let mut head = [0u8; HEADER];
-    file.read_exact(0, &mut head).ok()?;
+    file.read_exact(0, &mut head)?;
     if head[..MAGIC.len()] != MAGIC {
-        return None;
+        return Err(EINVAL);
     }
     let len = u32::from_le_bytes([head[8], head[9], head[10], head[11]]) as usize;
     let crc = u16::from_le_bytes([head[12], head[13]]);
     if len == 0 || len > MAX_CATACOMB || size != (HEADER + len) as u64 {
-        return None;
+        return Err(EINVAL);
     }
-    let mut blob: KVec<u8> = KVec::with_capacity(len, GFP_KERNEL).ok()?;
-    blob.resize(len, 0, GFP_KERNEL).ok()?;
-    file.read_exact(HEADER as u64, &mut blob).ok()?;
+    let mut blob: KVec<u8> = KVec::with_capacity(len, GFP_KERNEL)?;
+    blob.resize(len, 0, GFP_KERNEL)?;
+    file.read_exact(HEADER as u64, &mut blob)?;
     if crc16_ccitt_false(&blob) != crc {
-        return None;
+        return Err(EINVAL);
     }
-    Some(blob)
+    Ok(Some(blob))
+}
+
+/// True only for a present, valid file.
+pub(crate) fn is_saved(kind: u8) -> bool {
+    matches!(read(kind), Ok(Some(_)))
+}
+
+/// True only when the file is provably missing.
+pub(crate) fn is_absent(kind: u8) -> bool {
+    matches!(read(kind), Ok(None))
 }

drivers/soc/apple/diag.rs

@@ -1,3 +1,3 @@
 // SPDX-License-Identifier: GPL-2.0-only OR MIT
 
 //! Rust side of `diag_shim.c`: the passive diagnostics in sysfs.
@@ -30,6 +30,15 @@
         sepos13: bool,
         xart: bool,
     ) -> c_int;
+    fn sep_diag_set_policy(
+        provision_keybag: bool,
+        trusted_keys: bool,
+        filevault_api: bool,
+        xarm_trace: bool,
+        refkey_v2: bool,
+        identity_override: bool,
+    );
+    fn sep_diag_set_identity_source(source: c_uint);
     fn sep_diag_set_attach(attached: bool);
     fn sep_diag_set_endpoints(count: c_uint);
     fn sep_diag_set_keystore_open();
@@ -66,6 +75,28 @@
     Unproven = 3,
 }
 
+/// Boot-time policy, without identity values or key material.
+pub(crate) struct Policy {
+    pub provision_keybag: bool,
+    pub trusted_keys: bool,
+    pub filevault_api: bool,
+    pub xarm_trace: bool,
+    pub refkey_v2: bool,
+    pub identity_override: bool,
+}
+
+/// The source selected by prepare_os_uuid, not the UUID itself.
+pub(crate) enum IdentitySource {
+    DeviceTree = 1,
+    Override = 2,
+    Missing = 3,
+}
+
+pub(crate) fn identity_source(source: IdentitySource) {
+    // SAFETY: this only stores the source enum in the passive cache.
+    unsafe { sep_diag_set_identity_source(source as c_uint) };
+}
+
 /// Adds the `diag` group to the SEP device, with the facts fixed at probe. The
 /// group goes away when the driver unbinds.
 ///
@@ -76,6 +107,7 @@
     profile: &profile::PlatformProfile,
     xart_writable: bool,
     guard: Option<(u8, bool)>,
+    policy: Policy,
 ) -> Result {
     // Exhaustive, so a new bootstrap or key store fails to build here until
     // the ABI has a value for it.
@@ -98,6 +130,18 @@
     // SAFETY: no preconditions; stores three words.
     unsafe { sep_diag_set_xart_guard(c_uint::from(level), list_loaded, matching() as c_int) };
 
+    // SAFETY: the facts are fixed before the attribute group is published.
+    unsafe {
+        sep_diag_set_policy(
+            policy.provision_keybag,
+            policy.trusted_keys,
+            policy.filevault_api,
+            policy.xarm_trace,
+            policy.refkey_v2,
+            policy.identity_override,
+        )
+    };
+
     // SAFETY: `dev` is bound for the duration of the call, which is what devres
     // needs. `profile.name` is a `str`, valid for reads of `profile.name.len()`
     // bytes; the shim copies at most that many, needs no NUL terminator, and

drivers/soc/apple/diag_shim.c

@@ -23,7 +23,7 @@
 #include "shim.h"
 
 /* The contract version; see Documentation/ABI/testing/sysfs-driver-apple-sep. */
-#define SEP_DIAG_ABI			2
+#define SEP_DIAG_ABI			3
 
 #define SEP_DIAG_ATTACH_PENDING		0
 #define SEP_DIAG_ATTACH_ATTACHED	1
@@ -64,6 +64,13 @@ static struct {
 	bool cold;
 	bool sepos13;
 	bool xart;
+	bool provision_keybag;
+	bool trusted_keys;
+	bool filevault_api;
+	bool xarm_trace;
+	bool refkey_v2;
+	bool identity_override;
+	atomic_t identity_source;
 	/* The xART guard's effective level (0: none runs), and its list. */
 	unsigned int xart_guard;
 	bool xart_guard_list;
@@ -120,6 +127,54 @@ static ssize_t xart_show(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RO(xart);
 
+/* Parameter policy is captured at probe; the identity choice is cached later. */
+static ssize_t policy_show(struct device *dev, struct device_attribute *attr,
+			   char *buf)
+{
+	const char *identity;
+
+	switch (atomic_read(&sep_diag.identity_source)) {
+	case 1:
+		identity = "dt";
+		break;
+	case 2:
+		identity = "override";
+		break;
+	case 3:
+		identity = "missing";
+		break;
+	default:
+		identity = "pending";
+		break;
+	}
+	return sysfs_emit(buf,
+		"xart_writes=%u provision_keybag=%u xart_guard=%u "
+		"trusted_keys=%u filevault_api=%u xarm_trace=%u "
+		"refkey_v2=%u identity_override=%u identity_source=%s\n",
+		sep_diag.xart, sep_diag.provision_keybag, sep_diag.xart_guard,
+		sep_diag.trusted_keys, sep_diag.filevault_api, sep_diag.xarm_trace,
+		sep_diag.refkey_v2, sep_diag.identity_override, identity);
+}
+static DEVICE_ATTR_RO(policy);
+
+void sep_diag_set_policy(bool provision_keybag, bool trusted_keys,
+			 bool filevault_api, bool xarm_trace, bool refkey_v2,
+			 bool identity_override)
+{
+	sep_diag.provision_keybag = provision_keybag;
+	sep_diag.trusted_keys = trusted_keys;
+	sep_diag.filevault_api = filevault_api;
+	sep_diag.xarm_trace = xarm_trace;
+	sep_diag.refkey_v2 = refkey_v2;
+	sep_diag.identity_override = identity_override;
+	atomic_set(&sep_diag.identity_source, 0);
+}
+
+void sep_diag_set_identity_source(unsigned int source)
+{
+	atomic_set(&sep_diag.identity_source, source);
+}
+
 static ssize_t attach_show(struct device *dev, struct device_attribute *attr,
 			   char *buf)
 {
@@ -346,6 +401,7 @@ static struct attribute *sep_diag_attrs[] = {
 	&dev_attr_boot.attr,
 	&dev_attr_protocol.attr,
 	&dev_attr_xart.attr,
+	&dev_attr_policy.attr,
 	&dev_attr_attach.attr,
 	&dev_attr_endpoints.attr,
 	&dev_attr_keystore.attr,

drivers/soc/apple/keybag.rs

@@ -1,3 +1,3 @@
 // SPDX-License-Identifier: GPL-2.0-only OR MIT
 // Copyright 2026 Dj
 
@@ -177,6 +177,15 @@
         head[OFF_STATE + 3],
     ]);
     if state == STATE_REFUSED {
+        let expected_crc = crc16_ccitt_false(&checksum_input(state, &[], &[0; UUID_LEN], &[])?);
+        let crc = u16::from_le_bytes([head[OFF_CRC], head[OFF_CRC + 1]]);
+        if size != HEADER as u64
+            || crc != expected_crc
+            || head[OFF_LEN..OFF_CRC].iter().any(|byte| *byte != 0)
+            || head[OFF_CRC + 2..].iter().any(|byte| *byte != 0)
+        {
+            return Err(EINVAL);
+        }
         return Ok(State::Absent(NoStoredKeyBag { slot }));
     }
     let Some(provenance) = UuidProvenance::from_state(state) else {

drivers/soc/apple/profile.rs

@@ -1,3 +1,3 @@
 // SPDX-License-Identifier: GPL-2.0-only OR MIT
 // Copyright 2026 Dj
 // Copyright 2026 Ryan Murray
@@ -666,3 +666,30 @@
         }
     }
 }
+
+/// The owner-qualified J613 OS-firmware lane; system firmware may differ.
+pub(crate) fn j613_26_6_2() -> bool {
+    machine_has(b"apple,j613")
+        && chosen_string(c"asahi,os-fw-version")
+            .as_deref()
+            .is_some_and(os_firmware_26_6_2)
+}
+
+fn os_firmware_26_6_2(raw: &[u8]) -> bool {
+    raw == b"26.6.2" || raw == b"26.6.2\0"
+}
+
+#[cfg(CONFIG_APPLE_SEP_KUNIT_TEST)]
+#[kernel::macros::kunit_tests(apple_sep_j613_firmware)]
+mod j613_firmware_tests {
+    use super::*;
+
+    #[test]
+    fn exact_os_firmware_only() {
+        assert!(os_firmware_26_6_2(b"26.6.2"));
+        assert!(os_firmware_26_6_2(b"26.6.2\0"));
+        for raw in [&b"14.8.3"[..], &b"26.6.20"[..], &b"27.0"[..], &b""[..]] {
+            assert!(!os_firmware_26_6_2(raw));
+        }
+    }
+}

drivers/soc/apple/refkey.rs

@@ -1,3 +1,3 @@
 // SPDX-License-Identifier: GPL-2.0-only OR MIT
 // Copyright 2026 Dj
 //! Machine ref-key: Secure-Enclave key sealing, signing, and attestation.
@@ -177,7 +177,19 @@
             return;
         }
 
-        if let Ok(f) = shim::StoreFile::open_readonly(path) {
+        let existing = match shim::StoreFile::open_readonly(path) {
+            Ok(file) => Some(file),
+            Err(ENOENT) => None,
+            Err(error) => {
+                dev_err!(
+                    self.dev,
+                    "sks: cannot read existing machine ref-key: {:?}; refusing replacement\n",
+                    error
+                );
+                return;
+            }
+        };
+        if let Some(f) = existing {
             let sz = f.size().unwrap_or(0);
             if (1..=8192).contains(&sz) {
                 let mut blob: KVec<u8> = KVec::new();