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

[Stefan Berger <stefanb@linux.ibm.com>]

On 9/2/22 12:28, Mimi Zohar wrote:
> 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.
> 
> Reviewed-by: Petr Vorel <pvorel@suse.cz>
> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
> ---
>   src/evmctl.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++-----
>   1 file changed, 59 insertions(+), 6 deletions(-)
> 
> diff --git a/src/evmctl.c b/src/evmctl.c
> index 13b0105af8c4..641504047a36 100644
> --- a/src/evmctl.c
> +++ b/src/evmctl.c
> @@ -2295,6 +2295,11 @@ 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)
>   {
> @@ -2307,12 +2312,19 @@ 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;
> @@ -2334,6 +2346,23 @@ 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) {
> @@ -2342,13 +2371,30 @@ 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;
> @@ -2357,10 +2403,17 @@ 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;

Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>