Re: [PATCH v2 1/3] dm: introduce audit event module for device mapper
On Wed, 2021-08-18 at 14:59 -0400, Paul Moore wrote:
> On Sat, Aug 14, 2021 at 2:34 PM Michael Weiß
> wrote:
> > To be able to send auditing events to user space, we introduce
> > a generic dm-audit module. It provides helper functions to emit
> > audit events through the kernel audit subsystem. We claim the
> > AUDIT_DM type=1336 out of the audit event messages range in the
> > corresponding userspace api in 'include/uapi/linux/audit.h' for
> > those events.
> >
> > Following commits to device mapper targets actually will make
> > use of this to emit those events in relevant cases.
> >
> > Signed-off-by: Michael Weiß
>
> Hi Michael,
>
> You went into more detail in your patchset cover letter, e.g. example
> audit records, which I think would be helpful here in the commit
> description so we have it as part of the git log. I don't want to
> discourage you from writing cover letters, but don't forget that the
> cover letters can be lost to the ether after a couple of years whereas
> the git log has a much longer lifetime (we hope!) and a tighter
> binding to the related code.
Hi Paul,
at first thank you for your comments.
I see your point and I will respect that in providing the next version of
this patch-set.
>
> > ---
> > drivers/md/Kconfig | 10 +++
> > drivers/md/Makefile| 4 +++
> > drivers/md/dm-audit.c | 59 ++
> > drivers/md/dm-audit.h | 33 +
> > include/uapi/linux/audit.h | 1 +
> > 5 files changed, 107 insertions(+)
> > create mode 100644 drivers/md/dm-audit.c
> > create mode 100644 drivers/md/dm-audit.h
> >
> > diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
> > index 0602e82a9516..48adbec12148 100644
> > --- a/drivers/md/Kconfig
> > +++ b/drivers/md/Kconfig
> > @@ -608,6 +608,7 @@ config DM_INTEGRITY
> > select CRYPTO
> > select CRYPTO_SKCIPHER
> > select ASYNC_XOR
> > + select DM_AUDIT if AUDIT
> > help
> > This device-mapper target emulates a block device that has
> > additional per-sector tags that can be used for storing
> > @@ -640,4 +641,13 @@ config DM_ZONED
> >
> > If unsure, say N.
> >
> > +config DM_AUDIT
> > + bool "DM audit events"
> > + depends on AUDIT
> > + help
> > + Generate audit events for device-mapper.
> > +
> > + Enables audit logging of several security relevant events in the
> > + particular device-mapper targets, especially the integrity target.
> > +
> > endif # MD
> > diff --git a/drivers/md/Makefile b/drivers/md/Makefile
> > index a74aaf8b1445..4cd47623c742 100644
> > --- a/drivers/md/Makefile
> > +++ b/drivers/md/Makefile
> > @@ -103,3 +103,7 @@ endif
> > ifeq ($(CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG),y)
> > dm-verity-objs += dm-verity-verify-sig.o
> > endif
> > +
> > +ifeq ($(CONFIG_DM_AUDIT),y)
> > +dm-mod-objs+= dm-audit.o
> > +endif
> > diff --git a/drivers/md/dm-audit.c b/drivers/md/dm-audit.c
> > new file mode 100644
> > index ..c7e5824821bb
> > --- /dev/null
> > +++ b/drivers/md/dm-audit.c
> > @@ -0,0 +1,59 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Creating audit records for mapped devices.
> > + *
> > + * Copyright (C) 2021 Fraunhofer AISEC. All rights reserved.
> > + *
> > + * Authors: Michael Weiß
> > + */
> > +
> > +#include
> > +#include
> > +#include
> > +#include
> > +#include
> > +
> > +#include "dm-audit.h"
> > +#include "dm-core.h"
> > +
> > +void dm_audit_log_bio(const char *dm_msg_prefix, const char *op,
> > + struct bio *bio, sector_t sector, int result)
> > +{
> > + struct audit_buffer *ab;
> > +
> > + if (audit_enabled == AUDIT_OFF)
> > + return;
> > +
> > + ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_DM);
> > + if (unlikely(!ab))
> > + return;
> > +
> > + audit_log_format(ab, "module=%s dev=%d:%d op=%s sector=%llu res=%d",
> > +dm_msg_prefix, MAJOR(bio->bi_bdev->bd_dev),
> > +MINOR(bio->bi_bdev->bd_dev), op, sector, result);
> > + audit_log_end(ab);
> > +}
> > +EXPORT_SYMBOL_GPL(dm_audit_log_bio);
> > +
> > +void dm_audit_log_target(const char *dm_msg_prefix, const char *op,
> > +struct dm_target *ti, int result)
> > +{
> > + struct audit_buffer *ab;
> > + struct mapped_device *md = dm_table_get_md(ti->table);
> > +
> > + if (audit_enabled == AUDIT_OFF)
> > + return;
> > +
> > + ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_DM);
> > + if (unlikely(!ab))
> > + return;
> > +
> > + audit_log_format(ab, "module=%s dev=%s op=%s",
> > +dm_msg_prefix, dm_device_name(md), op);
> > +
> > + if (!result && !strcmp("ctr", op))
> > + audit_log_format(ab, " error_msg='%s'", ti->e
Re: [PATCH v2 1/3] dm: introduce audit event module for device mapper
On Sat, Aug 14, 2021 at 2:34 PM Michael Weiß
wrote:
>
> To be able to send auditing events to user space, we introduce
> a generic dm-audit module. It provides helper functions to emit
> audit events through the kernel audit subsystem. We claim the
> AUDIT_DM type=1336 out of the audit event messages range in the
> corresponding userspace api in 'include/uapi/linux/audit.h' for
> those events.
>
> Following commits to device mapper targets actually will make
> use of this to emit those events in relevant cases.
>
> Signed-off-by: Michael Weiß
Hi Michael,
You went into more detail in your patchset cover letter, e.g. example
audit records, which I think would be helpful here in the commit
description so we have it as part of the git log. I don't want to
discourage you from writing cover letters, but don't forget that the
cover letters can be lost to the ether after a couple of years whereas
the git log has a much longer lifetime (we hope!) and a tighter
binding to the related code.
> ---
> drivers/md/Kconfig | 10 +++
> drivers/md/Makefile| 4 +++
> drivers/md/dm-audit.c | 59 ++
> drivers/md/dm-audit.h | 33 +
> include/uapi/linux/audit.h | 1 +
> 5 files changed, 107 insertions(+)
> create mode 100644 drivers/md/dm-audit.c
> create mode 100644 drivers/md/dm-audit.h
>
> diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
> index 0602e82a9516..48adbec12148 100644
> --- a/drivers/md/Kconfig
> +++ b/drivers/md/Kconfig
> @@ -608,6 +608,7 @@ config DM_INTEGRITY
> select CRYPTO
> select CRYPTO_SKCIPHER
> select ASYNC_XOR
> + select DM_AUDIT if AUDIT
> help
> This device-mapper target emulates a block device that has
> additional per-sector tags that can be used for storing
> @@ -640,4 +641,13 @@ config DM_ZONED
>
> If unsure, say N.
>
> +config DM_AUDIT
> + bool "DM audit events"
> + depends on AUDIT
> + help
> + Generate audit events for device-mapper.
> +
> + Enables audit logging of several security relevant events in the
> + particular device-mapper targets, especially the integrity target.
> +
> endif # MD
> diff --git a/drivers/md/Makefile b/drivers/md/Makefile
> index a74aaf8b1445..4cd47623c742 100644
> --- a/drivers/md/Makefile
> +++ b/drivers/md/Makefile
> @@ -103,3 +103,7 @@ endif
> ifeq ($(CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG),y)
> dm-verity-objs += dm-verity-verify-sig.o
> endif
> +
> +ifeq ($(CONFIG_DM_AUDIT),y)
> +dm-mod-objs+= dm-audit.o
> +endif
> diff --git a/drivers/md/dm-audit.c b/drivers/md/dm-audit.c
> new file mode 100644
> index ..c7e5824821bb
> --- /dev/null
> +++ b/drivers/md/dm-audit.c
> @@ -0,0 +1,59 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Creating audit records for mapped devices.
> + *
> + * Copyright (C) 2021 Fraunhofer AISEC. All rights reserved.
> + *
> + * Authors: Michael Weiß
> + */
> +
> +#include
> +#include
> +#include
> +#include
> +#include
> +
> +#include "dm-audit.h"
> +#include "dm-core.h"
> +
> +void dm_audit_log_bio(const char *dm_msg_prefix, const char *op,
> + struct bio *bio, sector_t sector, int result)
> +{
> + struct audit_buffer *ab;
> +
> + if (audit_enabled == AUDIT_OFF)
> + return;
> +
> + ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_DM);
> + if (unlikely(!ab))
> + return;
> +
> + audit_log_format(ab, "module=%s dev=%d:%d op=%s sector=%llu res=%d",
> +dm_msg_prefix, MAJOR(bio->bi_bdev->bd_dev),
> +MINOR(bio->bi_bdev->bd_dev), op, sector, result);
> + audit_log_end(ab);
> +}
> +EXPORT_SYMBOL_GPL(dm_audit_log_bio);
> +
> +void dm_audit_log_target(const char *dm_msg_prefix, const char *op,
> +struct dm_target *ti, int result)
> +{
> + struct audit_buffer *ab;
> + struct mapped_device *md = dm_table_get_md(ti->table);
> +
> + if (audit_enabled == AUDIT_OFF)
> + return;
> +
> + ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_DM);
> + if (unlikely(!ab))
> + return;
> +
> + audit_log_format(ab, "module=%s dev=%s op=%s",
> +dm_msg_prefix, dm_device_name(md), op);
> +
> + if (!result && !strcmp("ctr", op))
> + audit_log_format(ab, " error_msg='%s'", ti->error);
> + audit_log_format(ab, " res=%d", result);
> + audit_log_end(ab);
> +}
Generally speaking we try to keep a consistent format and ordering
within a given audit record type. However you appear to have at least
three different formats for the AUDIT_DM record in this patch:
"... module=%s dev=%d:%d op=%s sector=%llu res=%d"
"... module=%s dev=%s op=%s error_msg='%s' res=%d"
"... module=%s dev=%s op=%s res=%d"
The first thing that j
[PATCH v2 1/3] dm: introduce audit event module for device mapper
To be able to send auditing events to user space, we introduce
a generic dm-audit module. It provides helper functions to emit
audit events through the kernel audit subsystem. We claim the
AUDIT_DM type=1336 out of the audit event messages range in the
corresponding userspace api in 'include/uapi/linux/audit.h' for
those events.
Following commits to device mapper targets actually will make
use of this to emit those events in relevant cases.
Signed-off-by: Michael Weiß
---
drivers/md/Kconfig | 10 +++
drivers/md/Makefile| 4 +++
drivers/md/dm-audit.c | 59 ++
drivers/md/dm-audit.h | 33 +
include/uapi/linux/audit.h | 1 +
5 files changed, 107 insertions(+)
create mode 100644 drivers/md/dm-audit.c
create mode 100644 drivers/md/dm-audit.h
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 0602e82a9516..48adbec12148 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -608,6 +608,7 @@ config DM_INTEGRITY
select CRYPTO
select CRYPTO_SKCIPHER
select ASYNC_XOR
+ select DM_AUDIT if AUDIT
help
This device-mapper target emulates a block device that has
additional per-sector tags that can be used for storing
@@ -640,4 +641,13 @@ config DM_ZONED
If unsure, say N.
+config DM_AUDIT
+ bool "DM audit events"
+ depends on AUDIT
+ help
+ Generate audit events for device-mapper.
+
+ Enables audit logging of several security relevant events in the
+ particular device-mapper targets, especially the integrity target.
+
endif # MD
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index a74aaf8b1445..4cd47623c742 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -103,3 +103,7 @@ endif
ifeq ($(CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG),y)
dm-verity-objs += dm-verity-verify-sig.o
endif
+
+ifeq ($(CONFIG_DM_AUDIT),y)
+dm-mod-objs+= dm-audit.o
+endif
diff --git a/drivers/md/dm-audit.c b/drivers/md/dm-audit.c
new file mode 100644
index ..c7e5824821bb
--- /dev/null
+++ b/drivers/md/dm-audit.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Creating audit records for mapped devices.
+ *
+ * Copyright (C) 2021 Fraunhofer AISEC. All rights reserved.
+ *
+ * Authors: Michael Weiß
+ */
+
+#include
+#include
+#include
+#include
+#include
+
+#include "dm-audit.h"
+#include "dm-core.h"
+
+void dm_audit_log_bio(const char *dm_msg_prefix, const char *op,
+ struct bio *bio, sector_t sector, int result)
+{
+ struct audit_buffer *ab;
+
+ if (audit_enabled == AUDIT_OFF)
+ return;
+
+ ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_DM);
+ if (unlikely(!ab))
+ return;
+
+ audit_log_format(ab, "module=%s dev=%d:%d op=%s sector=%llu res=%d",
+dm_msg_prefix, MAJOR(bio->bi_bdev->bd_dev),
+MINOR(bio->bi_bdev->bd_dev), op, sector, result);
+ audit_log_end(ab);
+}
+EXPORT_SYMBOL_GPL(dm_audit_log_bio);
+
+void dm_audit_log_target(const char *dm_msg_prefix, const char *op,
+struct dm_target *ti, int result)
+{
+ struct audit_buffer *ab;
+ struct mapped_device *md = dm_table_get_md(ti->table);
+
+ if (audit_enabled == AUDIT_OFF)
+ return;
+
+ ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_DM);
+ if (unlikely(!ab))
+ return;
+
+ audit_log_format(ab, "module=%s dev=%s op=%s",
+dm_msg_prefix, dm_device_name(md), op);
+
+ if (!result && !strcmp("ctr", op))
+ audit_log_format(ab, " error_msg='%s'", ti->error);
+ audit_log_format(ab, " res=%d", result);
+ audit_log_end(ab);
+}
+EXPORT_SYMBOL_GPL(dm_audit_log_target);
diff --git a/drivers/md/dm-audit.h b/drivers/md/dm-audit.h
new file mode 100644
index ..b9e31b9e3682
--- /dev/null
+++ b/drivers/md/dm-audit.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Creating audit records for mapped devices.
+ *
+ * Copyright (C) 2021 Fraunhofer AISEC. All rights reserved.
+ *
+ * Authors: Michael Weiß
+ */
+
+#ifndef DM_AUDIT_H
+#define DM_AUDIT_H
+
+#include
+
+#ifdef CONFIG_DM_AUDIT
+void dm_audit_log_bio(const char *dm_msg_prefix, const char *op,
+ struct bio *bio, sector_t sector, int result);
+void dm_audit_log_target(const char *dm_msg_prefix, const char *op,
+struct dm_target *ti, int result);
+#else
+static inline void dm_audit_log_bio(const char *dm_msg_prefix, const char *op,
+ struct bio *bio, sector_t sector,
+ int result)
+{
+}
+static inline void dm_audit_log_target(const char *dm_msg_prefix,
+ const char *op, struct dm_target *ti,
+
