ima-evm-utils: Add support for Intel TSS2 for PCR reading

This patch makes it possible to use the Intel TSS2 for getting
PCR values from the SHA1/SHA256 banks on a TPM2.
It is somewhat naive as it doesn't use the multi-PCR selection
that TSS2 is capable of, that is for a future patch.

Signed-off-by: Patrick Uiterwijk <patrick@puiterwijk.org>
[zohar@linux.ibm.com: added missing "stdint.h" in pcr_tsspcrread.c]
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

src/utils.c

@@ -0,0 +1,32 @@
+#include <stdint.h>
+
+#include "utils.h"
+
+int hex_to_bin(char ch)
+{
+	if ((ch >= '0') && (ch <= '9'))
+		return ch - '0';
+	ch = tolower(ch);
+	if ((ch >= 'a') && (ch <= 'f'))
+		return ch - 'a' + 10;
+	return -1;
+}
+
+int hex2bin(void *dst, const char *src, size_t count)
+{
+	int hi, lo;
+
+	while (count--) {
+		if (*src == ' ')
+			src++;
+
+		hi = hex_to_bin(*src++);
+		lo = hex_to_bin(*src++);
+
+		if ((hi < 0) || (lo < 0))
+			return -1;
+
+		*(uint8_t *)dst++ = (hi << 4) | lo;
+	}
+	return 0;
+}