Re: [dm-devel] [PATCH 6/7] dm: update target specific status functions to measure data

[Alasdair G Kergon <agk@redhat.com>]

On Mon, Jul 12, 2021 at 05:49:03PM -0700, Tushar Sugandhi wrote:
> The DM target data measured by IMA subsystem can alternatively
> be queried from userspace by setting DM_IMA_MEASUREMENT_FLAG with
> DM_TABLE_STATUS_CMD.

I was able to try this out - as 'dmsetup measure' - by applying the quick
patch below to the upstream LVM2 tree.
 
Alasdair


diff --git a/libdm/.exported_symbols.DM_1_02_179 b/libdm/.exported_symbols.DM_1_02_179
new file mode 100644
index 000000000..4ab603b68
--- /dev/null
+++ b/libdm/.exported_symbols.DM_1_02_179
@@ -0,0 +1 @@
+dm_task_ima_measurement
diff --git a/libdm/dm-tools/dmsetup.c b/libdm/dm-tools/dmsetup.c
index a3d1248bc..3e5983fef 100644
--- a/libdm/dm-tools/dmsetup.c
+++ b/libdm/dm-tools/dmsetup.c
@@ -2446,6 +2446,9 @@ static int _status(CMD_ARGS)
 	if (_switches[NOFLUSH_ARG] && !dm_task_no_flush(dmt))
 		goto_out;
 
+	if (!dm_task_ima_measurement(dmt))
+		goto_out;
+
 	if (!_task_run(dmt))
 		goto_out;
 
@@ -6262,6 +6265,7 @@ static struct command _dmsetup_commands[] = {
 	{"stats", "<command> [<options>] [<device>...]", 1, -1, 1, 1, _stats},
 	{"status", "[<device>...] [--noflush] [--target <target_type>]", 0, -1, 2, 0, _status},
 	{"table", "[<device>...] [--concise] [--target <target_type>] [--showkeys]", 0, -1, 2, 0, _status},
+	{"measure", "[<device>...]", 0, -1, 2, 0, _status},
 	{"wait", "<device> [<event_nr>] [--noflush]", 0, 2, 0, 0, _wait},
 	{"mknodes", "[<device>...]", 0, -1, 1, 0, _mknodes},
 	{"mangle", "[<device>...]", 0, -1, 1, 0, _mangle},
diff --git a/libdm/ioctl/libdm-iface.c b/libdm/ioctl/libdm-iface.c
index 47f14398c..22cce8e76 100644
--- a/libdm/ioctl/libdm-iface.c
+++ b/libdm/ioctl/libdm-iface.c
@@ -929,6 +929,13 @@ int dm_task_secure_data(struct dm_task *dmt)
 	return 1;
 }
 
+int dm_task_ima_measurement(struct dm_task *dmt)
+{
+	dmt->ima_measurement = 1;
+
+	return 1;
+}
+
 int dm_task_retry_remove(struct dm_task *dmt)
 {
 	dmt->retry_remove = 1;
@@ -1286,7 +1293,14 @@ static struct dm_ioctl *_flatten(struct dm_task *dmt, unsigned repeat_count)
 		}
 		dmi->flags |= DM_UUID_FLAG;
 	}
-
+	if (dmt->ima_measurement) {
+		if (_dm_version_minor < 45) {
+			log_error("WARNING: IMA measurement unsupported by "
+				  "kernel.  Aborting operation.");
+			goto bad;
+		}
+		dmi->flags |= DM_IMA_MEASUREMENT_FLAG;
+	}
 	dmi->target_count = count;
 	dmi->event_nr = dmt->event_nr;
 
@@ -1487,6 +1501,7 @@ static int _create_and_load_v4(struct dm_task *dmt)
 	task->head = dmt->head;
 	task->tail = dmt->tail;
 	task->secure_data = dmt->secure_data;
+	task->ima_measurement = dmt->ima_measurement;
 
 	r = dm_task_run(task);
 
@@ -1875,7 +1890,7 @@ static struct dm_ioctl *_do_dm_ioctl(struct dm_task *dmt, unsigned command,
 	}
 
 	log_debug_activation("dm %s %s%s %s%s%s %s%.0d%s%.0d%s"
-			     "%s[ %s%s%s%s%s%s%s%s%s] %.0" PRIu64 " %s [%u] (*%u)",
+			     "%s[ %s%s%s%s%s%s%s%s%s%s] %.0" PRIu64 " %s [%u] (*%u)",
 			     _cmd_data_v4[dmt->type].name,
 			     dmt->new_uuid ? "UUID " : "",
 			     dmi->name, dmi->uuid, dmt->newname ? " " : "",
@@ -1893,6 +1908,7 @@ static struct dm_ioctl *_do_dm_ioctl(struct dm_task *dmt, unsigned command,
 			     dmt->retry_remove ? "retryremove " : "",
 			     dmt->deferred_remove ? "deferredremove " : "",
 			     dmt->secure_data ? "securedata " : "",
+			     dmt->ima_measurement ? "ima_measurement " : "",
 			     dmt->query_inactive_table ? "inactive " : "",
 			     dmt->enable_checks ? "enablechecks " : "",
 			     dmt->sector, _sanitise_message(dmt->message),
diff --git a/libdm/ioctl/libdm-targets.h b/libdm/ioctl/libdm-targets.h
index 294210d2b..022b02c72 100644
--- a/libdm/ioctl/libdm-targets.h
+++ b/libdm/ioctl/libdm-targets.h
@@ -69,6 +69,7 @@ struct dm_task {
 	int enable_checks;
 	int expected_errno;
 	int ioctl_errno;
+	int ima_measurement;
 
 	int record_timestamp;
 
diff --git a/libdm/libdevmapper.h b/libdm/libdevmapper.h
index ac31b59da..e9412da7d 100644
--- a/libdm/libdevmapper.h
+++ b/libdm/libdevmapper.h
@@ -235,6 +235,7 @@ int dm_task_suppress_identical_reload(struct dm_task *dmt);
 int dm_task_secure_data(struct dm_task *dmt);
 int dm_task_retry_remove(struct dm_task *dmt);
 int dm_task_deferred_remove(struct dm_task *dmt);
+int dm_task_ima_measurement(struct dm_task *dmt);
 
 /*
  * Record timestamp immediately after the ioctl returns.
diff --git a/libdm/libdm-common.c b/libdm/libdm-common.c
index 708414676..d123e3ddf 100644
--- a/libdm/libdm-common.c
+++ b/libdm/libdm-common.c
@@ -336,6 +336,7 @@ struct dm_task *dm_task_create(int type)
 	dmt->new_uuid = 0;
 	dmt->secure_data = 0;
 	dmt->record_timestamp = 0;
+	dmt->ima_measurement = 0;
 
 	return dmt;
 }
diff --git a/libdm/misc/dm-ioctl.h b/libdm/misc/dm-ioctl.h
index 55dee2148..2b442ab70 100644
--- a/libdm/misc/dm-ioctl.h
+++ b/libdm/misc/dm-ioctl.h
@@ -1,6 +1,7 @@
+/* SPDX-License-Identifier: LGPL-2.0+ WITH Linux-syscall-note */
 /*
  * Copyright (C) 2001 - 2003 Sistina Software (UK) Limited.
- * Copyright (C) 2004 - 2017 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2004 - 2021 Red Hat, Inc. All rights reserved.
  *
  * This file is released under the LGPL.
  */
@@ -183,7 +184,7 @@ struct dm_target_spec {
 struct dm_target_deps {
 	uint32_t count;	/* Array size */
 	uint32_t padding;	/* unused */
-	uint64_t dev[];		/* out */
+	uint64_t dev[0];	/* out */
 };
 
 /*
@@ -193,9 +194,23 @@ struct dm_name_list {
 	uint64_t dev;
 	uint32_t next;		/* offset to the next record from
 				   the _start_ of this */
-	char name[];
+	char name[0];
+
+	/*
+	 * The following members can be accessed by taking a pointer that
+	 * points immediately after the terminating zero character in "name"
+	 * and aligning this pointer to next 8-byte boundary.
+	 * Uuid is present if the flag DM_NAME_LIST_FLAG_HAS_UUID is set.
+	 *
+	 * uint32_t event_nr;
+	 * uint32_t flags;
+	 * char uuid[0];
+	 */
 };
 
+#define DM_NAME_LIST_FLAG_HAS_UUID		1
+#define DM_NAME_LIST_FLAG_DOESNT_HAVE_UUID	2
+
 /*
  * Used to retrieve the target versions
  */
@@ -203,7 +218,7 @@ struct dm_target_versions {
         uint32_t next;
         uint32_t version[3];
 
-        char name[];
+        char name[0];
 };
 
 /*
@@ -212,7 +227,7 @@ struct dm_target_versions {
 struct dm_target_msg {
 	uint64_t sector;	/* Device sector */
 
-	char message[];
+	char message[0];
 };
 
 /*
@@ -267,15 +282,15 @@ enum {
 #define DM_TABLE_STATUS  _IOWR(DM_IOCTL, DM_TABLE_STATUS_CMD, struct dm_ioctl)
 
 #define DM_LIST_VERSIONS _IOWR(DM_IOCTL, DM_LIST_VERSIONS_CMD, struct dm_ioctl)
+#define DM_GET_TARGET_VERSION _IOWR(DM_IOCTL, DM_GET_TARGET_VERSION_CMD, struct dm_ioctl)
 
 #define DM_TARGET_MSG	 _IOWR(DM_IOCTL, DM_TARGET_MSG_CMD, struct dm_ioctl)
 #define DM_DEV_SET_GEOMETRY	_IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
-#define DM_GET_TARGET_VERSION	_IOWR(DM_IOCTL, DM_GET_TARGET_VERSION_CMD, struct dm_ioctl)
 
 #define DM_VERSION_MAJOR	4
-#define DM_VERSION_MINOR	36
+#define DM_VERSION_MINOR	45
 #define DM_VERSION_PATCHLEVEL	0
-#define DM_VERSION_EXTRA	"-ioctl (2017-06-09)"
+#define DM_VERSION_EXTRA	"-ioctl (2021-03-22)"
 
 /* Status bits */
 #define DM_READONLY_FLAG	(1 << 0) /* In/Out */
@@ -363,4 +378,10 @@ enum {
  */
 #define DM_INTERNAL_SUSPEND_FLAG	(1 << 18) /* Out */
 
+/*
+ * If set, returns in the in buffer passed by UM, the raw table information
+ * that would be measured by IMA subsystem on device state change.
+ */
+#define DM_IMA_MEASUREMENT_FLAG	(1 << 19) /* In */
+
 #endif				/* _LINUX_DM_IOCTL_H */

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