linux-kernel - [PATCH v2 2/3] libnvdimm/security: the 'security' attr never show 'overwrite' state

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon,  3 Aug 2020 16:41:38 -0600
From:   Jane Chu <jane.chu@...cle.com>
To:     dan.j.williams@...el.com, vishal.l.verma@...el.com,
        dave.jiang@...el.com, ira.weiny@...el.com, jmoyer@...hat.com,
        linux-nvdimm@...ts.01.org, linux-kernel@...r.kernel.org
Cc:     jane.chu@...cle.com
Subject: [PATCH v2 2/3] libnvdimm/security: the 'security' attr never show 'overwrite' state

'security' attribute displays the security state of an nvdimm.
During normal operation, the nvdimm state maybe one of 'disabled',
'unlocked' or 'locked'.  When an admin issues
  # ndctl sanitize-dimm nmem0 --overwrite
the attribute is expected to change to 'overwrite' until the overwrite
operation completes.

But tests on our systems show that 'overwrite' is never shown during
the overwrite operation. i.e.
  # cat /sys/devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0012:00/ndbus0/nmem0/security
  unlocked
the attribute remain 'unlocked' through out the operation, consequently
"ndctl wait-overwrite nmem0" command doesn't wait at all.

The driver tracks the state in 'nvdimm->sec.flags': when the operation
starts, it adds an overwrite bit to the flags; and when the operation
completes, it removes the bit. Hence security_show() should check the
'overwrite' bit first, in order to indicate the actual state when multiple
bits are set in the flags.

Signed-off-by: Jane Chu <jane.chu@...cle.com>
Reviewed-by: Dave Jiang <dave.jiang@...el.com>
---
 drivers/nvdimm/dimm_devs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 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;
 }

-- 
1.8.3.1