On Tue, Jul 23, 2019 at 04:27:06PM -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.
>
> Sample error messages:
> Failed to read PCRs: (tsspcrread failed: No such file or directory)
> Failed to read PCRs: (TSS_Dev_Open: Error opening /dev/tpmrm0)
>
> Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
> ---
> Changelog v3:
> - Suggested by Vitaly, replace snprintf() & strdup() with asprintf().
>
> Changelog v2:
> - Fix "errmsg" not always being initialized within tpm_pcr_read2().
> Reported by Bruno.
> - Shortened error msg length.
> - Renamed tpm_pcr_read2() to tpm2_pcr_read().
> - Included Petr Vorel's autotool change, which looks for tsspcrread,
> rather than the tss library.
>
> 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 | 7 +++++++
> src/evmctl.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++----
> 2 files changed, 60 insertions(+), 4 deletions(-)
>
> diff --git a/configure.ac b/configure.ac
> index 9beb4b6c2377..3fc63b367c91 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -7,6 +7,7 @@ AC_CONFIG_HEADERS([config.h])
> AC_CONFIG_MACRO_DIR([m4])
>
> AC_CANONICAL_HOST
> +AC_USE_SYSTEM_EXTENSIONS
>
> # Checks for programs.
> AC_PROG_CC
> @@ -29,6 +30,11 @@ AC_SUBST(KERNEL_HEADERS)
> AC_CHECK_HEADER(unistd.h)
> AC_CHECK_HEADERS(openssl/conf.h)
>
> +AC_CHECK_PROG(TSSPCRREAD, [tsspcrread], yes, no)
> +if test "x$TSSPCRREAD" = "xyes"; then
> + AC_DEFINE(HAVE_TSSPCRREAD, 1, [Define to 1 if you have tsspcrread binary installed])],
> +fi
> +
> 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 +77,5 @@ echo
> echo "Configuration:"
> echo " debug: $pkg_cv_enable_debug"
> echo " openssl-conf: $enable_openssl_conf"
> +echo " tsspcrread: $TSSPCRREAD"
> echo
> diff --git a/src/evmctl.c b/src/evmctl.c
> index 9e0926f10404..3289061fe8d2 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 +1400,43 @@ static int tpm_pcr_read(int idx, uint8_t *pcr, int len)
> return result;
> }
>
> +#ifdef HAVE_TSSPCRREAD
> +static int tpm2_pcr_read(int idx, uint8_t *hwpcr, int len, char **errmsg)
> +{
> + FILE *fp;
> + char pcr[100]; /* may contain an error */
> + char cmd[50];
> + int ret;
> +
> + sprintf(cmd, "tsspcrread -halg sha1 -ha %d -ns 2> /dev/null", idx);
> + fp = popen(cmd, "r");
> + if (!fp) {
> + ret = asprintf(errmsg, "popen failed: %s", strerror(errno));
> + if (ret == -1) /* the contents of errmsg is undefined */
> + *errmsg = NULL;
> + return -1;
> + }
> +
> + if (fgets(pcr, sizeof(pcr), fp) == NULL) {
> + ret = asprintf(errmsg, "tsspcrread failed: %s",
> + strerror(errno));
> + if (ret == -1) /* the contents of errmsg is undefined */
> + *errmsg = NULL;
> + ret = pclose(fp);
> + return -1;
> + }
> +
> + /* get the popen "cmd" return code */
> + ret = pclose(fp);
> + if (!ret)
> + hex2bin(hwpcr, pcr, SHA_DIGEST_LENGTH);
> + else
> + *errmsg = strndup(pcr, strlen(pcr) - 1); /* remove newline */
> +
> + return ret;
> +}
> +#endif
> +
> #define TCG_EVENT_NAME_LEN_MAX 255
>
> struct template_entry {
> @@ -1658,8 +1693,22 @@ 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 HAVE_TSSPCRREAD
> + char *errmsg = NULL;
> +
> + err = tpm2_pcr_read(i, hwpcr, sizeof(hwpcr), &errmsg);
> + if (err) {
> + log_info("Failed to read PCRs: (%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
>
Looks good to me.
thanks Mimi!
Reviewed-by: Bruno E. O. Meneguele <bmeneg@xxxxxxxxxx>
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