Mimi,
On Tue, Jul 16, 2019 at 10:30:16AM -0400, Mimi Zohar wrote:
> When keys are not provided, the default key is used to verify the file
> signature, resulting in this erroneous message. Before using the default
> key to verify the file signature, verify the keyid is correct.
1. What is default key when keys are not provided?
2. I don't see keyid verification in the patch.
3. Now we have so complicated keyfile handling.
>
> Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
> ---
> src/libimaevm.c | 19 ++++++++++---------
> 1 file changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/src/libimaevm.c b/src/libimaevm.c
> index ae487f9fe36c..472ab53c7b42 100644
> --- a/src/libimaevm.c
> +++ b/src/libimaevm.c
> @@ -302,6 +302,9 @@ EVP_PKEY *read_pub_pkey(const char *keyfile, int x509)
> X509 *crt = NULL;
> EVP_PKEY *pkey = NULL;
>
> + if (!keyfile)
> + return NULL;
> +
> fp = fopen(keyfile, "r");
> if (!fp) {
> log_err("Failed to open keyfile: %s\n", keyfile);
> @@ -569,27 +572,25 @@ static int get_hash_algo_from_sig(unsigned char *sig)
> int verify_hash(const char *file, const unsigned char *hash, int size, unsigned char *sig,
> int siglen)
> {
> - const char *key;
> - int x509;
> + const char *key = NULL;
> verify_hash_fn_t verify_hash;
>
> /* Get signature type from sig header */
> if (sig[0] == DIGSIG_VERSION_1) {
> verify_hash = verify_hash_v1;
> +
> /* Read pubkey from RSA key */
> - x509 = 0;
> + if (!params.keyfile)
> + key = "/etc/keys/pubkey_evm.pem";
> } else if (sig[0] == DIGSIG_VERSION_2) {
> verify_hash = verify_hash_v2;
> +
> /* Read pubkey from x509 cert */
> - x509 = 1;
> + if (!params.keyfile)
> + init_public_keys("/etc/keys/x509_evm.der");
Also, in "ima-evm-utils: Preload public keys for ima_verify" I call
init_public_keys in cmd_verify_ima() which calls this verify_hash().
So there will be double calling of init_public_keys().
ps. Btw, I think we should remove this verify_hash_fn_t indirect call
trick and replace it with two normal calls in each if branch.
verify_hash() calling verify_hash() obscures cscope, and with direct
calls it will be easier to parse. I may send patch for this.
Thanks,
> } else
> return -1;
>
> - /* Determine what key to use for verification*/
> - key = params.keyfile ? : x509 ?
> - "/etc/keys/x509_evm.der" :
> - "/etc/keys/pubkey_evm.pem";
> -
> return verify_hash(file, hash, size, sig, siglen, key);
> }
>
> --
> 2.7.5
