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Open Source and information security mailing list archives
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Date: Fri, 16 Aug 2019 16:34:53 -0400
From: Jeff Moyer <jmoyer@...hat.com>
To: Dan Williams <dan.j.williams@...el.com>
Cc: linux-nvdimm@...ts.01.org, Dave Jiang <dave.jiang@...el.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] libnvdimm/security: Introduce a 'frozen' attribute
Dan Williams <dan.j.williams@...el.com> writes:
> In the process of debugging a system with an NVDIMM that was failing to
> unlock it was found that the kernel is reporting 'locked' while the DIMM
> security interface is 'frozen'. Unfortunately the security state is
> tracked internally as an enum which prevents it from communicating the
> difference between 'locked' and 'locked + frozen'. It follows that the
> enum also prevents the kernel from communicating 'unlocked + frozen'
> which would be useful for debugging why security operations like 'change
> passphrase' are disabled.
>
> Ditch the security state enum for a set of flags and introduce a new
> sysfs attribute explicitly for the 'frozen' state. The regression risk
> is low because the 'frozen' state was already blocked behind the
> 'locked' state, but will need to revisit if there were cases where
> applications need 'frozen' to show up in the primary 'security'
> attribute. The expectation is that communicating 'frozen' is mostly a
> helper for debug and status monitoring.
>
> Cc: Dave Jiang <dave.jiang@...el.com>
> Reported-by: Jeff Moyer <jmoyer@...hat.com>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
> drivers/acpi/nfit/intel.c | 65 ++++++++++++++-----------
> drivers/nvdimm/bus.c | 2 -
> drivers/nvdimm/dimm_devs.c | 59 +++++++++++++----------
> drivers/nvdimm/nd-core.h | 21 ++++++--
> drivers/nvdimm/security.c | 99 ++++++++++++++++++--------------------
> include/linux/libnvdimm.h | 9 ++-
> tools/testing/nvdimm/dimm_devs.c | 19 ++-----
> 7 files changed, 146 insertions(+), 128 deletions(-)
>
> diff --git a/drivers/acpi/nfit/intel.c b/drivers/acpi/nfit/intel.c
> index cddd0fcf622c..2c51ca4155dc 100644
> --- a/drivers/acpi/nfit/intel.c
> +++ b/drivers/acpi/nfit/intel.c
> @@ -7,10 +7,11 @@
> #include "intel.h"
> #include "nfit.h"
>
> -static enum nvdimm_security_state intel_security_state(struct nvdimm *nvdimm,
> +static unsigned long intel_security_flags(struct nvdimm *nvdimm,
> enum nvdimm_passphrase_type ptype)
> {
> struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm);
> + unsigned long security_flags = 0;
> struct {
> struct nd_cmd_pkg pkg;
> struct nd_intel_get_security_state cmd;
> @@ -27,46 +28,54 @@ static enum nvdimm_security_state intel_security_state(struct nvdimm *nvdimm,
> int rc;
>
> if (!test_bit(NVDIMM_INTEL_GET_SECURITY_STATE, &nfit_mem->dsm_mask))
> - return -ENXIO;
> + return 0;
>
> /*
> * Short circuit the state retrieval while we are doing overwrite.
> * The DSM spec states that the security state is indeterminate
> * until the overwrite DSM completes.
> */
> - if (nvdimm_in_overwrite(nvdimm) && ptype == NVDIMM_USER)
> - return NVDIMM_SECURITY_OVERWRITE;
> + if (nvdimm_in_overwrite(nvdimm) && ptype == NVDIMM_USER) {
> + set_bit(NVDIMM_SECURITY_OVERWRITE, &security_flags);
> + return security_flags;
> + }
Why not just
return BIT(NVDIMM_SECURITY_OVERWRITE);
?
> rc = nvdimm_ctl(nvdimm, ND_CMD_CALL, &nd_cmd, sizeof(nd_cmd), NULL);
> - if (rc < 0)
> - return rc;
> - if (nd_cmd.cmd.status)
> - return -EIO;
> + if (rc < 0 || nd_cmd.cmd.status) {
> + pr_err("%s: security state retrieval failed (%d:%#x)\n",
> + nvdimm_name(nvdimm), rc, nd_cmd.cmd.status);
> + return 0;
> + }
>
> /* check and see if security is enabled and locked */
> if (ptype == NVDIMM_MASTER) {
> if (nd_cmd.cmd.extended_state & ND_INTEL_SEC_ESTATE_ENABLED)
> - return NVDIMM_SECURITY_UNLOCKED;
> - else if (nd_cmd.cmd.extended_state &
> - ND_INTEL_SEC_ESTATE_PLIMIT)
> - return NVDIMM_SECURITY_FROZEN;
> - } else {
> - if (nd_cmd.cmd.state & ND_INTEL_SEC_STATE_UNSUPPORTED)
> - return -ENXIO;
> - else if (nd_cmd.cmd.state & ND_INTEL_SEC_STATE_ENABLED) {
> - if (nd_cmd.cmd.state & ND_INTEL_SEC_STATE_LOCKED)
> - return NVDIMM_SECURITY_LOCKED;
> - else if (nd_cmd.cmd.state & ND_INTEL_SEC_STATE_FROZEN
> - || nd_cmd.cmd.state &
> - ND_INTEL_SEC_STATE_PLIMIT)
> - return NVDIMM_SECURITY_FROZEN;
> - else
> - return NVDIMM_SECURITY_UNLOCKED;
> - }
> + set_bit(NVDIMM_SECURITY_UNLOCKED, &security_flags);
> + else
> + set_bit(NVDIMM_SECURITY_DISABLED, &security_flags);
> + if (nd_cmd.cmd.extended_state & ND_INTEL_SEC_ESTATE_PLIMIT)
> + set_bit(NVDIMM_SECURITY_FROZEN, &security_flags);
> + return security_flags;
> }
>
> - /* this should cover master security disabled as well */
> - return NVDIMM_SECURITY_DISABLED;
> +
Extra space.
> + if (nd_cmd.cmd.state & ND_INTEL_SEC_STATE_UNSUPPORTED)
> + return 0;
> +
> + if (nd_cmd.cmd.state & ND_INTEL_SEC_STATE_ENABLED) {
> + if (nd_cmd.cmd.state & ND_INTEL_SEC_STATE_FROZEN)
> + set_bit(NVDIMM_SECURITY_FROZEN, &security_flags);
> + if (nd_cmd.cmd.state & ND_INTEL_SEC_STATE_PLIMIT)
> + set_bit(NVDIMM_SECURITY_FROZEN, &security_flags);
Change to the following?
+ if (nd_cmd.cmd.state & ND_INTEL_SEC_STATE_FROZEN ||
+ nd_cmd.cmd.state & ND_INTEL_SEC_STATE_PLIMIT)
+ set_bit(NVDIMM_SECURITY_FROZEN, &security_flags);
[...]
> +
> + if (nd_cmd.cmd.state & ND_INTEL_SEC_STATE_LOCKED)
> + set_bit(NVDIMM_SECURITY_LOCKED, &security_flags);
> + else
> + set_bit(NVDIMM_SECURITY_UNLOCKED, &security_flags);
I was going to comment on 2 bits being overkill, but you addressed that
in the enum. :)
The rest looks good.
-Jeff
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