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* [PATCH 2/2] libnvdimm/security: ensure sysfs poll thread woke up and fetch updated attr
@ 2020-07-24  4:10 Jane Chu
  2020-07-24  4:10 ` [PATCH 1/2] libnvdimm/security: 'security' attr never show 'overwrite' state Jane Chu
  0 siblings, 1 reply; 3+ messages in thread
From: Jane Chu @ 2020-07-24  4:10 UTC (permalink / raw)
  To: dan.j.williams, vishal.l.verma, dave.jiang, ira.weiny, jmoyer,
	linux-nvdimm, linux-kernel
  Cc: jane.chu

commit 7d988097c546 ("acpi/nfit, libnvdimm/security: Add security DSM overwrite support")
adds a sysfs_notify_dirent() to wake up userspace poll thread when the "overwrite"
operation has completed. But the notification is issued before the internal
dimm security state and flags have been updated, so the userspace poll thread
wakes up and fetches the not-yet-updated attr and falls back to sleep, forever.
But if user from another terminal issue "ndctl wait-overwrite nmemX" again,
the command returns instantly.

Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Fixes: 7d988097c546 ("acpi/nfit, libnvdimm/security: Add security DSM overwrite support")
Signed-off-by: Jane Chu <jane.chu@oracle.com>
---
 drivers/nvdimm/security.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/nvdimm/security.c b/drivers/nvdimm/security.c
index 8f3971c..4b80150 100644
--- a/drivers/nvdimm/security.c
+++ b/drivers/nvdimm/security.c
@@ -450,14 +450,19 @@ void __nvdimm_security_overwrite_query(struct nvdimm *nvdimm)
 	else
 		dev_dbg(&nvdimm->dev, "overwrite completed\n");
 
-	if (nvdimm->sec.overwrite_state)
-		sysfs_notify_dirent(nvdimm->sec.overwrite_state);
+	/*
+	 * Mark the overwrite work done and update dimm security flags,
+	 * then send a sysfs event notification to wake up userspace
+	 * poll threads to picked up the changed state.
+	 */
 	nvdimm->sec.overwrite_tmo = 0;
 	clear_bit(NDD_SECURITY_OVERWRITE, &nvdimm->flags);
 	clear_bit(NDD_WORK_PENDING, &nvdimm->flags);
-	put_device(&nvdimm->dev);
 	nvdimm->sec.flags = nvdimm_security_flags(nvdimm, NVDIMM_USER);
 	nvdimm->sec.ext_flags = nvdimm_security_flags(nvdimm, NVDIMM_MASTER);
+	if (nvdimm->sec.overwrite_state)
+		sysfs_notify_dirent(nvdimm->sec.overwrite_state);
+	put_device(&nvdimm->dev);
 }
 
 void nvdimm_security_overwrite_query(struct work_struct *work)
-- 
1.8.3.1
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^ permalink raw reply	[flat|nested] 3+ messages in thread

* [PATCH 1/2] libnvdimm/security: 'security' attr never show 'overwrite' state
  2020-07-24  4:10 [PATCH 2/2] libnvdimm/security: ensure sysfs poll thread woke up and fetch updated attr Jane Chu
@ 2020-07-24  4:10 ` Jane Chu
  0 siblings, 0 replies; 3+ messages in thread
From: Jane Chu @ 2020-07-24  4:10 UTC (permalink / raw)
  To: dan.j.williams, vishal.l.verma, dave.jiang, ira.weiny, jmoyer,
	linux-nvdimm, linux-kernel
  Cc: jane.chu

Since
commit d78c620a2e82 ("libnvdimm/security: Introduce a 'frozen' attribute"),
when issue

then immediately check the 'security' attribute,

unlocked

Actually the attribute stays 'unlocked' through out the entire overwrite
operation, never changed.  That's because 'nvdimm->sec.flags' is a bitmap
that has both bits set indicating 'overwrite' and 'unlocked'.
But security_show() checks the mutually exclusive bits before it checks
the 'overwrite' bit at last. The order should be reversed.

The commit also has a typo: in one occasion, 'nvdimm->sec.ext_state'
assignment is replaced with 'nvdimm->sec.flags' assignment for
the NVDIMM_MASTER type.

Cc: Dan Williams <dan.j.williams@intel.com>
Fixes: d78c620a2e82 ("libnvdimm/security: Introduce a 'frozen' attribute")
Signed-off-by: Jane Chu <jane.chu@oracle.com>
---
 drivers/nvdimm/dimm_devs.c | 4 ++--
 drivers/nvdimm/security.c  | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c
index b7b77e8..5d72026 100644
--- a/drivers/nvdimm/dimm_devs.c
+++ b/drivers/nvdimm/dimm_devs.c
@@ -363,14 +363,14 @@ __weak ssize_t security_show(struct device *dev,
 {
 	struct nvdimm *nvdimm = to_nvdimm(dev);
 
+	if (test_bit(NVDIMM_SECURITY_OVERWRITE, &nvdimm->sec.flags))
+		return sprintf(buf, "overwrite\n");
 	if (test_bit(NVDIMM_SECURITY_DISABLED, &nvdimm->sec.flags))
 		return sprintf(buf, "disabled\n");
 	if (test_bit(NVDIMM_SECURITY_UNLOCKED, &nvdimm->sec.flags))
 		return sprintf(buf, "unlocked\n");
 	if (test_bit(NVDIMM_SECURITY_LOCKED, &nvdimm->sec.flags))
 		return sprintf(buf, "locked\n");
-	if (test_bit(NVDIMM_SECURITY_OVERWRITE, &nvdimm->sec.flags))
-		return sprintf(buf, "overwrite\n");
 	return -ENOTTY;
 }
 
diff --git a/drivers/nvdimm/security.c b/drivers/nvdimm/security.c
index 4cef69b..8f3971c 100644
--- a/drivers/nvdimm/security.c
+++ b/drivers/nvdimm/security.c
@@ -457,7 +457,7 @@ void __nvdimm_security_overwrite_query(struct nvdimm *nvdimm)
 	clear_bit(NDD_WORK_PENDING, &nvdimm->flags);
 	put_device(&nvdimm->dev);
 	nvdimm->sec.flags = nvdimm_security_flags(nvdimm, NVDIMM_USER);
-	nvdimm->sec.flags = nvdimm_security_flags(nvdimm, NVDIMM_MASTER);
+	nvdimm->sec.ext_flags = nvdimm_security_flags(nvdimm, NVDIMM_MASTER);
 }
 
 void nvdimm_security_overwrite_query(struct work_struct *work)
-- 
1.8.3.1
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To unsubscribe send an email to linux-nvdimm-leave@lists.01.org

^ permalink raw reply	[flat|nested] 3+ messages in thread

* [PATCH 2/2] libnvdimm/security: ensure sysfs poll thread woke up and fetch updated attr
  2020-07-24 16:09 Jane Chu
@ 2020-07-24 16:09 ` Jane Chu
  0 siblings, 0 replies; 3+ messages in thread
From: Jane Chu @ 2020-07-24 16:09 UTC (permalink / raw)
  To: dan.j.williams, vishal.l.verma, dave.jiang, ira.weiny, jmoyer,
	linux-nvdimm, linux-kernel
  Cc: jane.chu

commit 7d988097c546 ("acpi/nfit, libnvdimm/security: Add security DSM overwrite support")
adds a sysfs_notify_dirent() to wake up userspace poll thread when the "overwrite"
operation has completed. But the notification is issued before the internal
dimm security state and flags have been updated, so the userspace poll thread
wakes up and fetches the not-yet-updated attr and falls back to sleep, forever.
But if user from another terminal issue "ndctl wait-overwrite nmemX" again,
the command returns instantly.

Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Fixes: 7d988097c546 ("acpi/nfit, libnvdimm/security: Add security DSM overwrite support")
Signed-off-by: Jane Chu <jane.chu@oracle.com>
---
 drivers/nvdimm/security.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/nvdimm/security.c b/drivers/nvdimm/security.c
index 8f3971c..4b80150 100644
--- a/drivers/nvdimm/security.c
+++ b/drivers/nvdimm/security.c
@@ -450,14 +450,19 @@ void __nvdimm_security_overwrite_query(struct nvdimm *nvdimm)
 	else
 		dev_dbg(&nvdimm->dev, "overwrite completed\n");
 
-	if (nvdimm->sec.overwrite_state)
-		sysfs_notify_dirent(nvdimm->sec.overwrite_state);
+	/*
+	 * Mark the overwrite work done and update dimm security flags,
+	 * then send a sysfs event notification to wake up userspace
+	 * poll threads to picked up the changed state.
+	 */
 	nvdimm->sec.overwrite_tmo = 0;
 	clear_bit(NDD_SECURITY_OVERWRITE, &nvdimm->flags);
 	clear_bit(NDD_WORK_PENDING, &nvdimm->flags);
-	put_device(&nvdimm->dev);
 	nvdimm->sec.flags = nvdimm_security_flags(nvdimm, NVDIMM_USER);
 	nvdimm->sec.ext_flags = nvdimm_security_flags(nvdimm, NVDIMM_MASTER);
+	if (nvdimm->sec.overwrite_state)
+		sysfs_notify_dirent(nvdimm->sec.overwrite_state);
+	put_device(&nvdimm->dev);
 }
 
 void nvdimm_security_overwrite_query(struct work_struct *work)
-- 
1.8.3.1
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org

^ permalink raw reply	[flat|nested] 3+ messages in thread

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2020-07-24  4:10 [PATCH 2/2] libnvdimm/security: ensure sysfs poll thread woke up and fetch updated attr Jane Chu
2020-07-24  4:10 ` [PATCH 1/2] libnvdimm/security: 'security' attr never show 'overwrite' state Jane Chu
2020-07-24 16:09 Jane Chu
2020-07-24 16:09 ` [PATCH 2/2] libnvdimm/security: ensure sysfs poll thread woke up and fetch updated attr Jane Chu

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