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[11/12] tpm: add the null key name as a sysfs export

Message ID 93740b6b42e67caa2a1854520b7e68f0966e5024.camel@HansenPartnership.com (mailing list archive)
State New
Headers show
Series add integrity and security to TPM2 transactions | expand

Commit Message

James Bottomley Feb. 16, 2023, 8:40 p.m. UTC
This is the last component of encrypted tpm2 session handling that
allows us to verify from userspace that the key derived from the NULL
seed genuinely belongs to the TPM and has not been spoofed.

The procedure for doing this involves creating an attestation identity
key (which requires verification of the TPM EK certificate) and then
using that AIK to sign a certification of the Elliptic Curve key over
the NULL seed.  Userspace must create this EC Key using the parameters
prescribed in TCG TPM v2.0 Provisioning Guidance for the SRK ECC; if
this is done correctly the names will match and the TPM can then run a
TPM2_Certify operation on this derived primary key using the newly
created AIK.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
---
 drivers/char/tpm/tpm-sysfs.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

Comments

kernel test robot Feb. 17, 2023, 10:59 a.m. UTC | #1
Hi James,

I love your patch! Perhaps something to improve:

[auto build test WARNING on char-misc/char-misc-testing]
[also build test WARNING on char-misc/char-misc-next char-misc/char-misc-linus herbert-cryptodev-2.6/master linus/master v6.2-rc8 next-20230217]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/James-Bottomley/crypto-lib-implement-library-version-of-AES-in-CFB-mode/20230217-044329
patch link:    https://lore.kernel.org/r/93740b6b42e67caa2a1854520b7e68f0966e5024.camel%40HansenPartnership.com
patch subject: [PATCH 11/12] tpm: add the null key name as a sysfs export
config: nios2-randconfig-m041-20230217 (https://download.01.org/0day-ci/archive/20230217/202302171852.zpg5jNaj-lkp@intel.com/config)
compiler: nios2-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/4c35ecc57dfd3fd82341cd20dfc30c5f665ba952
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review James-Bottomley/crypto-lib-implement-library-version-of-AES-in-CFB-mode/20230217-044329
        git checkout 4c35ecc57dfd3fd82341cd20dfc30c5f665ba952
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=nios2 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=nios2 SHELL=/bin/bash drivers/char/tpm/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202302171852.zpg5jNaj-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/char/tpm/tpm-sysfs.c:344:5: warning: "CONFIG_TPM_BUS_SECURITY" is not defined, evaluates to 0 [-Wundef]
     344 | #if CONFIG_TPM_BUS_SECURITY
         |     ^~~~~~~~~~~~~~~~~~~~~~~


vim +/CONFIG_TPM_BUS_SECURITY +344 drivers/char/tpm/tpm-sysfs.c

   341	
   342	static struct attribute *tpm2_dev_attrs[] = {
   343		&dev_attr_tpm_version_major.attr,
 > 344	#if CONFIG_TPM_BUS_SECURITY
   345		&dev_attr_null_name.attr,
   346	#endif
   347		NULL
   348	};
   349
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Patch

diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index 54c71473aa29..6044a2765da2 100644
--- a/drivers/char/tpm/tpm-sysfs.c
+++ b/drivers/char/tpm/tpm-sysfs.c
@@ -309,6 +309,21 @@  static ssize_t tpm_version_major_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(tpm_version_major);
 
+#ifdef CONFIG_TPM_BUS_SECURITY
+static ssize_t null_name_show(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	struct tpm_chip *chip = to_tpm_chip(dev);
+	int size = TPM2_NAME_SIZE;
+
+	bin2hex(buf, chip->tpmkeyname, size);
+	size *= 2;
+	buf[size++] = '\n';
+	return size;
+}
+static DEVICE_ATTR_RO(null_name);
+#endif
+
 static struct attribute *tpm1_dev_attrs[] = {
 	&dev_attr_pubek.attr,
 	&dev_attr_pcrs.attr,
@@ -326,6 +341,9 @@  static struct attribute *tpm1_dev_attrs[] = {
 
 static struct attribute *tpm2_dev_attrs[] = {
 	&dev_attr_tpm_version_major.attr,
+#if CONFIG_TPM_BUS_SECURITY
+	&dev_attr_null_name.attr,
+#endif
 	NULL
 };