To be resistant to timing attacks all cryptodev operations should be using a
version of memcmp that takes constant time.

There is no such function in std libc maybe make a new one?

Examples in current code base:


~/.../main/drivers/crypto $ git grep memcmp
armv8/rte_armv8_pmd.c:          if (memcmp(adst, op->sym->auth.digest.data,
ccp/ccp_crypto.c:               if (memcmp(dst, op->sym->auth.digest.data,
ccp/ccp_crypto.c:               if (memcmp(addr + offset, digest_data,
cnxk/cnxk_ae.h:         if (memcmp(rsa->sign.data, rsa->message.data,
cnxk/cnxk_se.h: if (memcmp(mac, gen_mac, mac_len))
ipsec_mb/pmd_aesni_gcm.c:               if (memcmp(tag, digest,
session->req_digest_length) != 0)
ipsec_mb/pmd_aesni_gcm.c:       return memcmp(digest, tmpdigest,
s->req_digest_length) == 0 ? 0
ipsec_mb/pmd_aesni_mb.c:        if (memcmp(job->auth_tag_output, crc,
RTE_ETHER_CRC_LEN) != 0)
ipsec_mb/pmd_aesni_mb.c:        if (memcmp(job->auth_tag_output, digest, len)
!= 0)
ipsec_mb/pmd_aesni_mb.c:                        if (memcmp(vec->digest[i].va,
dgst[i], len) != 0)
ipsec_mb/pmd_snow3g.c:                  if (memcmp(dst,
ops[i]->sym->auth.digest.data,
ipsec_mb/pmd_zuc.c:                     if (memcmp(dst[i],
ops[i]->sym->auth.digest.data,
mlx5/mlx5_crypto_dek.c: return memcmp(key, dek->data, xkey_len);
nitrox/nitrox_sym_reqmgr.c:     if (!memcmp(ctx->salt, addr,
AES_GCM_SALT_SIZE))
octeontx/otx_cryptodev_ops.c:           if (memcmp(rsa->sign.data,
rsa->message.data,
openssl/rte_openssl_pmd.c:              if (CRYPTO_memcmp(dst,
op->sym->auth.digest.data,
openssl/rte_openssl_pmd.c:              if (CRYPTO_memcmp(tmp,
op->rsa.message.data,
openssl/rte_openssl_pmd.c:              if ((ret <= 0) || (CRYPTO_memcmp(tmp,
op->rsa.message.data,
scheduler/rte_cryptodev_scheduler.c:            return
!memcmp(&sec_cap1->docsis, &sec_cap2->docsis,
uadk/uadk_crypto_pmd.c:                 if (memcmp(dst,
op->sym->auth.digest.data,