Re: [ima-evm-utils PATCH 12/12] Define and use a file specific "keypass" variable

Stefan Berger
2023-11-22T14:22:49Z

On 11/19/23 11:50, Mimi Zohar wrote:
> Instead of relying on the "imaevm_params.keypass" global variable, which
> is not concurrency-safe, add keypass as a parameter to the static library
> functions definitions. Update function callers.
>
> To avoid library incompatablity, don't remove imaevm_params.keypass
> variable.
>
> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
> ---
> src/evmctl.c | 9 +++++----
> src/libimaevm.c | 17 ++++++++---------
> 2 files changed, 13 insertions(+), 13 deletions(-)
>
> diff --git a/src/evmctl.c b/src/evmctl.c
> index b802eeb1bf15..6d6160159a1f 100644
> --- a/src/evmctl.c
> +++ b/src/evmctl.c
> @@ -141,6 +141,7 @@ static bool evm_portable;
> static bool veritysig;
> static bool hwtpm;
> static char *hash_algo;
> +static char *keypass;
>
> #define HMAC_FLAG_NO_UUID 0x0001
> #define HMAC_FLAG_CAPS_SET 0x0002
> @@ -3082,9 +3083,9 @@ int main(int argc, char *argv[])
> break;
> case 'p':
> if (optarg)
> - imaevm_params.keypass = optarg;
> + keypass = optarg;
> else
> - imaevm_params.keypass = get_password();
> + keypass = get_password();
> break;
> case 'f':
> sigfile = 1;
> @@ -3226,8 +3227,8 @@ int main(int argc, char *argv[])
> }
> }
>
> - if (!imaevm_params.keypass)
> - imaevm_params.keypass = getenv("EVMCTL_KEY_PASSWORD");
> + if (!keypass)
> + keypass = getenv("EVMCTL_KEY_PASSWORD");
>
> if (imaevm_params.keyfile != NULL &&
> imaevm_params.eng == NULL &&

The problem at this point in evmctl is that keypass is never passed to
anywhere. You have to pass it to sign_hash().

> diff --git a/src/libimaevm.c b/src/libimaevm.c
> index 18b6a6f27237..10ec847da08a 100644
> --- a/src/libimaevm.c
> +++ b/src/libimaevm.c
> @@ -1124,7 +1124,8 @@ static int get_hash_algo_v1(const char *algo)
> }
>
> static int sign_hash_v1(const char *hashalgo, const unsigned char *hash,
> - int size, const char *keyfile, unsigned char *sig)
> + int size, const char *keyfile, const char *keypass,
> + unsigned char *sig)
> {
> int len = -1, hashalgo_idx;
> SHA_CTX ctx;
> @@ -1158,7 +1159,7 @@ static int sign_hash_v1(const char *hashalgo, const unsigned char *hash,
> log_info("hash(%s): ", hashalgo);
> log_dump(hash, size);
>
> - key = read_priv_key(keyfile, imaevm_params.keypass);
> + key = read_priv_key(keyfile, keypass);
> if (!key)
> return -1;
>
> @@ -1211,7 +1212,8 @@ out:
> * Return: -1 signing error, >0 length of signature
> */
> static int sign_hash_v2(const char *algo, const unsigned char *hash,
> - int size, const char *keyfile, unsigned char *sig)
> + int size, const char *keyfile, const char *keypass,
> + unsigned char *sig)
> {
> struct signature_v2_hdr *hdr;
> int len = -1;
> @@ -1246,7 +1248,7 @@ static int sign_hash_v2(const char *algo, const unsigned char *hash,
> log_info("hash(%s): ", algo);
> log_dump(hash, size);
>
> - pkey = read_priv_pkey(keyfile, imaevm_params.keypass);
> + pkey = read_priv_pkey(keyfile, keypass);
> if (!pkey)
> return -1;
>
> @@ -1316,14 +1318,11 @@ err:
>
> int sign_hash(const char *hashalgo, const unsigned char *hash, int size, const char *keyfile, const char *keypass, unsigned char *sig)
> {
> - if (keypass)
> - imaevm_params.keypass = keypass;
> -

I hope all library callers, other than evmctl, passed the keypass in
already, otherwise they could have set the password via
imaevm_params.keypass global and passed in NULL and for them this will
be a behavioral change. Anyway, you have no other choice to get rid of
imaevm_params as much as possible, so I guess it's ok.

It looks like at this point imaevm_params.keypass doesn't have a single
user anymore so you could rename it to 'unused1' or so in the stucture
since it will have zero effect for anyone to set it.

> if (imaevm_params.x509)
> - return sign_hash_v2(hashalgo, hash, size, keyfile, sig);
> + return sign_hash_v2(hashalgo, hash, size, keyfile, keypass, sig);
> #if CONFIG_SIGV1
> else
> - return sign_hash_v1(hashalgo, hash, size, keyfile, sig);
> + return sign_hash_v1(hashalgo, hash, size, keyfile, keypass, sig);
> #endif
> log_info("Signature version 1 deprecated.");
> return -1;