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ima_evm_utils: erroneous "verification failed: 0 (invalid padding)" message

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When public keys are specified on the boot command line (--key "<public
key file>,[<public key file>,...]"), the appropriate public key is used
to verify EVM or file signatures.  If no keys are specified, the default
x509_evm.der or pubkey_evm.pem file is used to verify the DIGSIG_VERSION_2
or DIGSIG_VERSION_1 signatures respectively, without first checking the
keyids.  Instead of emitting a "verification failed: 0 (invalid
padding)" message, an "unknown keyid" message would be clearer.

To address this problem, when no public keys are specified, this patch
loads the x509_evm.der default public key onto the "public_keys" list,
while the pubkey_evm.pem continues to be passed to verify_hash_v1()

Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
This commit is contained in:
Mimi Zohar 2019-07-16 21:36:29 -04:00
parent a225728550
commit 388f807a0f
2 changed files with 18 additions and 13 deletions
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14
src/evmctl.c
View File

@ -838,6 +838,11 @@ static int cmd_verify_evm(struct command *cmd)
return -1; return -1;
} }
if (params.keyfile) /* Support multiple public keys */
init_public_keys(params.keyfile);
else /* assume read pubkey from x509 cert */
init_public_keys("/etc/keys/x509_evm.der");
err = verify_evm(file); err = verify_evm(file);
if (!err && params.verbose >= LOG_INFO) if (!err && params.verbose >= LOG_INFO)
log_info("%s: verification is OK\n", file); log_info("%s: verification is OK\n", file);
@ -879,8 +884,10 @@ static int cmd_verify_ima(struct command *cmd)
char *file = g_argv[optind++]; char *file = g_argv[optind++];
int err; int err;
if (params.keyfile) if (params.keyfile) /* Support multiple public keys */
init_public_keys(params.keyfile); init_public_keys(params.keyfile);
else /* assume read pubkey from x509 cert */
init_public_keys("/etc/keys/x509_evm.der");
errno = 0; errno = 0;
if (!file) { if (!file) {
@ -1602,9 +1609,10 @@ static int ima_measurement(const char *file)
return -1; return -1;
} }
/* Support multiple public keys */ if (params.keyfile) /* Support multiple public keys */
if (params.keyfile)
init_public_keys(params.keyfile); init_public_keys(params.keyfile);
else /* assume read pubkey from x509 cert */
init_public_keys("/etc/keys/x509_evm.der");
while (fread(&entry.header, sizeof(entry.header), 1, fp)) { while (fread(&entry.header, sizeof(entry.header), 1, fp)) {
ima_extend_pcr(pcr[entry.header.pcr], entry.header.digest, ima_extend_pcr(pcr[entry.header.pcr], entry.header.digest,

17
src/libimaevm.c
View File

@ -302,6 +302,9 @@ EVP_PKEY *read_pub_pkey(const char *keyfile, int x509)
X509 *crt = NULL; X509 *crt = NULL;
EVP_PKEY *pkey = NULL; EVP_PKEY *pkey = NULL;
if (!keyfile)
return NULL;
fp = fopen(keyfile, "r"); fp = fopen(keyfile, "r");
if (!fp) { if (!fp) {
log_err("Failed to open keyfile: %s\n", keyfile); log_err("Failed to open keyfile: %s\n", keyfile);
@ -569,27 +572,21 @@ 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 verify_hash(const char *file, const unsigned char *hash, int size, unsigned char *sig,
int siglen) int siglen)
{ {
const char *key; const char *key = NULL;
int x509;
verify_hash_fn_t verify_hash; verify_hash_fn_t verify_hash;
/* Get signature type from sig header */ /* Get signature type from sig header */
if (sig[0] == DIGSIG_VERSION_1) { if (sig[0] == DIGSIG_VERSION_1) {
verify_hash = verify_hash_v1; verify_hash = verify_hash_v1;
/* Read pubkey from RSA key */ /* Read pubkey from RSA key */
x509 = 0; if (!params.keyfile)
key = "/etc/keys/pubkey_evm.pem";
} else if (sig[0] == DIGSIG_VERSION_2) { } else if (sig[0] == DIGSIG_VERSION_2) {
verify_hash = verify_hash_v2; verify_hash = verify_hash_v2;
/* Read pubkey from x509 cert */
x509 = 1;
} else } else
return -1; 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); return verify_hash(file, hash, size, sig, siglen, key);
} }