[RFC PATCH ima-evm-utils 05/11] Replace the low level SHA1 calls when calculating the TPM 1.2 PCRs

[Mimi Zohar <zohar@xxxxxxxxxxxxx>]

OpenSSL v3 emits deprecated warnings for SHA1 functions.  Use the
EVP_ functions when walking the TPM 1.2 binary bios measurements
to calculate the TPM 1.2 PCRs.

Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
---
 src/evmctl.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 59 insertions(+), 6 deletions(-)

diff --git a/src/evmctl.c b/src/evmctl.c
index 621136b5b85f..6534950f3683 100644
--- a/src/evmctl.c
+++ b/src/evmctl.c
@@ -2296,6 +2296,11 @@ static int cmd_ima_measurement(struct command *cmd)
 	return ima_measurement(file);
 }
 
+/*
+ * read_binary_bios_measurements - read the TPM 1.2 event log
+ *
+ * Returns 0 on success, 1 on failure.
+ */
 #define MAX_EVENT_DATA_SIZE 200000
 static int read_binary_bios_measurements(char *file, struct tpm_bank_info *bank)
 {
@@ -2308,12 +2313,19 @@ static int read_binary_bios_measurements(char *file, struct tpm_bank_info *bank)
 		} header;
 		unsigned char data[MAX_EVENT_DATA_SIZE];
 	} event;
+	EVP_MD_CTX *mdctx;
+	const EVP_MD *md;
+	unsigned int mdlen;
+	int evp_err = 1;	/* success */
 	struct stat s;
 	FILE *fp;
-	SHA_CTX c;
 	int err = 0;
 	int len;
 	int i;
+#if OPENSSL_VERSION_NUMBER < 0x10100000
+	EVP_MD_CTX ctx;
+	mdctx = &ctx;
+#endif
 
 	if (stat(file, &s) == -1) {
 		errno = 0;
@@ -2335,6 +2347,23 @@ static int read_binary_bios_measurements(char *file, struct tpm_bank_info *bank)
 	if (imaevm_params.verbose > LOG_INFO)
 		log_info("Reading the TPM 1.2 event log %s.\n", file);
 
+	md = EVP_get_digestbyname(bank->algo_name);
+	if (!md) {
+		log_errno("Unknown message digest %s\n", bank->algo_name);
+		errno = 0;
+		fclose(fp);
+		return 1;
+	}
+
+#if OPENSSL_VERSION_NUMBER >= 0x10100000
+	mdctx = EVP_MD_CTX_new();
+	if (!mdctx) {
+		log_err("EVP_MD_CTX_new failed\n");
+		fclose(fp);
+		return 1;
+	}
+#endif
+
 	/* Extend the pseudo TPM PCRs with the event digest */
 	while (fread(&event, sizeof(event.header), 1, fp) == 1) {
 		if (imaevm_params.verbose > LOG_INFO) {
@@ -2343,13 +2372,30 @@ static int read_binary_bios_measurements(char *file, struct tpm_bank_info *bank)
 		}
 		if (event.header.pcr >= NUM_PCRS) {
 			log_err("Invalid PCR %d.\n", event.header.pcr);
-			err = 1;
 			break;
 		}
-		SHA1_Init(&c);
-		SHA1_Update(&c, bank->pcr[event.header.pcr], 20);
-		SHA1_Update(&c, event.header.digest, 20);
-		SHA1_Final(bank->pcr[event.header.pcr], &c);
+
+		evp_err = EVP_DigestInit(mdctx, md);
+		if (evp_err == 0) {
+			log_err("EVP_DigestInit() failed\n");
+			break;
+		}
+
+		evp_err = EVP_DigestUpdate(mdctx, bank->pcr[event.header.pcr], 20);
+		if (evp_err == 0) {
+			log_err("EVP_DigestUpdate() failed\n");
+			break;
+		}
+		evp_err = EVP_DigestUpdate(mdctx, event.header.digest, 20);
+		if (evp_err == 0) {
+			log_err("EVP_DigestUpdate() failed\n");
+			break;
+		}
+		evp_err = EVP_DigestFinal(mdctx, bank->pcr[event.header.pcr], &mdlen);
+		if (evp_err == 0) {
+			log_err("EVP_DigestFinal() failed\n");
+			break;
+		}
 		if (event.header.len > MAX_EVENT_DATA_SIZE) {
 			log_err("Event data event too long.\n");
 			err = 1;
@@ -2358,10 +2404,17 @@ static int read_binary_bios_measurements(char *file, struct tpm_bank_info *bank)
 		len = fread(event.data, event.header.len, 1, fp);
 		if (len != 1) {
 			log_errno("Failed reading event data (short read)\n");
+			err = 1;
 			break;
 		}
 	}
+
+	if (evp_err == 0) /* EVP_ functions return 1 on success, 0 on failure */
+		err = 1;
 	fclose(fp);
+#if OPENSSL_VERSION_NUMBER >= 0x10100000
+	EVP_MD_CTX_free(mdctx);
+#endif
 
 	if (imaevm_params.verbose <= LOG_INFO)
 		return err;
-- 
2.31.1