Hi Mirian,
On Mon, Jul 22, 2019 at 05:14:40PM -0400, Mimi Zohar wrote:
> The kernel does not expose the crypto agile TPM 2.0 PCR banks to
> userspace like it exposes PCRs for TPM 1.2. As a result, a userspace
> application is required to read PCRs.
>
> This patch adds tsspcrread support for reading the TPM 2.0 PCRs.
> tsspcrread is one application included in the ibmtss package.
>
> Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
> ---
> Changelog v1:
> - Based on Vitaly's review, test the popen "cmd" return code. Use
> pclose to determine if the result of the popen command succeeded or
> failed. Removed the now unneeded checking for spaces.
> - Dynamically allocated the error msg and other changes based on
> Vitaly's review.
> - Based on Bruno's review, reverted the return code change. At some
> point, we'll need to re-visit the return codes in general.
>
> configure.ac | 3 +++
> src/Makefile.am | 3 +++
> src/evmctl.c | 48 ++++++++++++++++++++++++++++++++++++++++++++----
> 3 files changed, 50 insertions(+), 4 deletions(-)
>
> diff --git a/configure.ac b/configure.ac
> index 9beb4b6c2377..40fea93fef2f 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -28,6 +28,8 @@ PKG_CHECK_MODULES(LIBCRYPTO, [libcrypto >= 0.9.8 ])
> AC_SUBST(KERNEL_HEADERS)
> AC_CHECK_HEADER(unistd.h)
> AC_CHECK_HEADERS(openssl/conf.h)
> +AC_SEARCH_LIBS(TSS_Transmit, ibmtss, [have_ibmtss=yes], [have_ibmtss=no])
> +AM_CONDITIONAL([CONFIG_IBMTSS], [test "x$have_ibmtss" = "xyes"])
>
> AC_CHECK_HEADERS(sys/xattr.h, , [AC_MSG_ERROR([sys/xattr.h header not found. You need the c-library development package.])])
> AC_CHECK_HEADERS(keyutils.h, , [AC_MSG_ERROR([keyutils.h header not found. You need the libkeyutils development package.])])
> @@ -71,4 +73,5 @@ echo
> echo "Configuration:"
> echo " debug: $pkg_cv_enable_debug"
> echo " openssl-conf: $enable_openssl_conf"
> +echo " ibmtss: $have_ibmtss"
> echo
> diff --git a/src/Makefile.am b/src/Makefile.am
> index 9c037e21dc4f..f0990fb01210 100644
> --- a/src/Makefile.am
> +++ b/src/Makefile.am
> @@ -21,6 +21,9 @@ evmctl_SOURCES = evmctl.c
> evmctl_CPPFLAGS = $(AM_CPPFLAGS) $(LIBCRYPTO_CFLAGS)
> evmctl_LDFLAGS = $(LDFLAGS_READLINE)
> evmctl_LDADD = $(LIBCRYPTO_LIBS) -lkeyutils libimaevm.la
> +if CONFIG_IBMTSS
> +evmctl_CFLAGS = -DIBMTSS
> +endif
>
> AM_CPPFLAGS = -I$(top_srcdir) -include config.h
>
> diff --git a/src/evmctl.c b/src/evmctl.c
> index 9e0926f10404..f726b2186678 100644
> --- a/src/evmctl.c
> +++ b/src/evmctl.c
> @@ -1383,10 +1383,8 @@ static int tpm_pcr_read(int idx, uint8_t *pcr, int len)
> if (!fp)
> fp = fopen(misc_pcrs, "r");
>
> - if (!fp) {
> - log_err("Unable to open %s or %s\n", pcrs, misc_pcrs);
> + if (!fp)
> return -1;
> - }
>
> for (;;) {
> p = fgets(buf, sizeof(buf), fp);
> @@ -1402,6 +1400,32 @@ static int tpm_pcr_read(int idx, uint8_t *pcr, int len)
> return result;
> }
>
> +#ifdef IBMTSS
> +static int tpm_pcr_read2(int idx, uint8_t *hwpcr, int len, char **errmsg)
> +{
> + FILE *fp;
> + char pcr[100]; /* may contain an error */
> + char cmd[36];
> + int ret;
> +
> + sprintf(cmd, "tsspcrread -halg sha1 -ha %d -ns", idx);
> + fp = popen(cmd, "r");
> + if (!fp)
> + return -1;
If popen() call fails, **errmsg won't be allocated and will crash in
ima_measurement() when it make use of errmsg within if(err), see below.
> +
> + fgets(pcr, sizeof(pcr), fp);
> +
> + /* get the popen "cmd" return code */
> + ret = pclose(fp);
> + if (!ret)
> + hex2bin(hwpcr, pcr, SHA_DIGEST_LENGTH);
> + else
> + *errmsg = strdup(pcr);
*errmsg is allocated only in case popen runs fine.
> +
> + return ret;
> +}
> +#endif
> +
> #define TCG_EVENT_NAME_LEN_MAX 255
>
> struct template_entry {
> @@ -1658,8 +1682,24 @@ static int ima_measurement(const char *file)
> log_info("PCRAgg %.2d: ", i);
> log_dump(pcr[i], SHA_DIGEST_LENGTH);
>
> - if (tpm_pcr_read(i, hwpcr, sizeof(hwpcr)))
> + if (tpm_pcr_read(i, hwpcr, sizeof(hwpcr))) {
> +#ifdef IBMTSS
> + char *errmsg = NULL;
> +
> + err = tpm_pcr_read2(i, hwpcr, sizeof(hwpcr), &errmsg);
> + if (err) {
> + errmsg[strlen(errmsg) - 1] = 0;
crash here: errmsg wasn't initialized within tpm_pcr_read2().
> +
> + log_info("Failed to read either TPM 1.2 or TPM 2.0 PCRs.\n (%s)\n", errmsg);
> + free(errmsg);
> + exit(1);
> + }
> +#else
> + log_info("Failed to read TPM 1.2 PCRs.\n");
> exit(1);
> +#endif
> + }
> +
> log_info("HW PCR-%d: ", i);
> log_dump(hwpcr, sizeof(hwpcr));
>
> --
> 2.7.5
>
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