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/*
* HMS: we need to test:
* - OpenSSL versions, if we are building with them
* - our versions
*
* We may need to test with(out) OPENSSL separately.
*/
#include <config.h>
#include "crypto.h"
#include <ctype.h>
#include "isc/string.h"
#include "ntp_md5.h"
#ifndef EVP_MAX_MD_SIZE
# define EVP_MAX_MD_SIZE 32
#endif
struct key *key_ptr;
size_t key_cnt = 0;
typedef struct key Key_T;
static u_int
compute_mac(
u_char digest[EVP_MAX_MD_SIZE],
char const * macname,
void const * pkt_data,
u_int pkt_size,
void const * key_data,
u_int key_size
)
{
u_int len = 0;
size_t slen = 0;
int key_type;
INIT_SSL();
key_type = keytype_from_text(macname, NULL);
#if defined(OPENSSL) && defined(ENABLE_CMAC)
/* Check if CMAC key type specific code required */
if (key_type == NID_cmac) {
CMAC_CTX * ctx = NULL;
u_char keybuf[AES_128_KEY_SIZE];
/* adjust key size (zero padded buffer) if necessary */
if (AES_128_KEY_SIZE > key_size) {
memcpy(keybuf, key_data, key_size);
memset((keybuf + key_size), 0,
(AES_128_KEY_SIZE - key_size));
key_data = keybuf;
}
if (!(ctx = CMAC_CTX_new())) {
msyslog(LOG_ERR, "make_mac: CMAC %s CTX new failed.", CMAC);
}
else if (!CMAC_Init(ctx, key_data, AES_128_KEY_SIZE,
EVP_aes_128_cbc(), NULL)) {
msyslog(LOG_ERR, "make_mac: CMAC %s Init failed.", CMAC);
}
else if (!CMAC_Update(ctx, pkt_data, (size_t)pkt_size)) {
msyslog(LOG_ERR, "make_mac: CMAC %s Update failed.", CMAC);
}
else if (!CMAC_Final(ctx, digest, &slen)) {
msyslog(LOG_ERR, "make_mac: CMAC %s Final failed.", CMAC);
slen = 0;
}
len = (u_int)slen;
CMAC_CTX_cleanup(ctx);
/* Test our AES-128-CMAC implementation */
} else /* MD5 MAC handling */
#endif
{
EVP_MD_CTX * ctx;
if (!(ctx = EVP_MD_CTX_new())) {
msyslog(LOG_ERR, "make_mac: MAC %s Digest CTX new failed.",
macname);
goto mac_fail;
}
#ifdef OPENSSL /* OpenSSL 1 supports return codes 0 fail, 1 okay */
# ifdef EVP_MD_CTX_FLAG_NON_FIPS_ALLOW
EVP_MD_CTX_set_flags(ctx, EVP_MD_CTX_FLAG_NON_FIPS_ALLOW);
# endif
/* [Bug 3457] DON'T use plain EVP_DigestInit! It would
* kill the flags! */
if (!EVP_DigestInit_ex(ctx, EVP_get_digestbynid(key_type), NULL)) {
msyslog(LOG_ERR, "make_mac: MAC %s Digest Init failed.",
macname);
goto mac_fail;
}
if (!EVP_DigestUpdate(ctx, key_data, key_size)) {
msyslog(LOG_ERR, "make_mac: MAC %s Digest Update key failed.",
macname);
goto mac_fail;
}
if (!EVP_DigestUpdate(ctx, pkt_data, pkt_size)) {
msyslog(LOG_ERR, "make_mac: MAC %s Digest Update data failed.",
macname);
goto mac_fail;
}
if (!EVP_DigestFinal(ctx, digest, &len)) {
msyslog(LOG_ERR, "make_mac: MAC %s Digest Final failed.",
macname);
len = 0;
}
#else /* !OPENSSL */
EVP_DigestInit(ctx, EVP_get_digestbynid(key_type));
EVP_DigestUpdate(ctx, key_data, key_size);
EVP_DigestUpdate(ctx, pkt_data, pkt_size);
EVP_DigestFinal(ctx, digest, &len);
#endif
mac_fail:
EVP_MD_CTX_free(ctx);
}
return len;
}
int
make_mac(
const void * pkt_data,
int pkt_size,
int mac_size,
Key_T const * cmp_key,
void * digest
)
{
u_int len;
u_char dbuf[EVP_MAX_MD_SIZE];
if (cmp_key->key_len > 64 || mac_size <= 0)
return 0;
if (pkt_size % 4 != 0)
return 0;
len = compute_mac(dbuf, cmp_key->typen,
pkt_data, (u_int)pkt_size,
cmp_key->key_seq, (u_int)cmp_key->key_len);
if (len) {
if (len > (u_int)mac_size)
len = (u_int)mac_size;
memcpy(digest, dbuf, len);
}
return (int)len;
}
/* Generates a md5 digest of the key specified in keyid concatenated with the
* ntp packet (exluding the MAC) and compares this digest to the digest in
* the packet's MAC. If they're equal this function returns 1 (packet is
* authentic) or else 0 (not authentic).
*/
int
auth_md5(
void const * pkt_data,
int pkt_size,
int mac_size,
Key_T const * cmp_key
)
{
u_int len = 0;
u_char const * pkt_ptr = pkt_data;
u_char dbuf[EVP_MAX_MD_SIZE];
if (mac_size <= 0 || (size_t)mac_size > sizeof(dbuf))
return FALSE;
len = compute_mac(dbuf, cmp_key->typen,
pkt_ptr, (u_int)pkt_size,
cmp_key->key_seq, (u_int)cmp_key->key_len);
pkt_ptr += pkt_size + 4;
if (len > (u_int)mac_size)
len = (u_int)mac_size;
/* isc_tsmemcmp will be better when its easy to link with. sntp
* is a 1-shot program, so snooping for timing attacks is
* Harder.
*/
return ((u_int)mac_size == len) && !memcmp(dbuf, pkt_ptr, len);
}
static int
hex_val(
unsigned char x
)
{
int val;
if ('0' <= x && x <= '9')
val = x - '0';
else if ('a' <= x && x <= 'f')
val = x - 'a' + 0xa;
else if ('A' <= x && x <= 'F')
val = x - 'A' + 0xA;
else
val = -1;
return val;
}
/* Load keys from the specified keyfile into the key structures.
* Returns -1 if the reading failed, otherwise it returns the
* number of keys it read
*/
int
auth_init(
const char *keyfile,
struct key **keys
)
{
FILE *keyf = fopen(keyfile, "r");
struct key *prev = NULL;
int scan_cnt, line_cnt = 1;
char kbuf[200];
char keystring[129];
/* HMS: Is it OK to do this later, after we know we have a key file? */
INIT_SSL();
if (keyf == NULL) {
if (debug)
printf("sntp auth_init: Couldn't open key file %s for reading!\n", keyfile);
return -1;
}
if (feof(keyf)) {
if (debug)
printf("sntp auth_init: Key file %s is empty!\n", keyfile);
fclose(keyf);
return -1;
}
key_cnt = 0;
while (!feof(keyf)) {
char * octothorpe;
struct key *act;
int goodline = 0;
if (NULL == fgets(kbuf, sizeof(kbuf), keyf))
continue;
kbuf[sizeof(kbuf) - 1] = '\0';
octothorpe = strchr(kbuf, '#');
if (octothorpe)
*octothorpe = '\0';
act = emalloc(sizeof(*act));
/* keep width 15 = sizeof struct key.typen - 1 synced */
scan_cnt = sscanf(kbuf, "%d %15s %128s",
&act->key_id, act->typen, keystring);
if (scan_cnt == 3) {
int len = strlen(keystring);
goodline = 1; /* assume best for now */
if (len <= 20) {
act->key_len = len;
memcpy(act->key_seq, keystring, len + 1);
} else if ((len & 1) != 0) {
goodline = 0; /* it's bad */
} else {
int j;
act->key_len = len >> 1;
for (j = 0; j < len; j+=2) {
int val;
val = (hex_val(keystring[j]) << 4) |
hex_val(keystring[j+1]);
if (val < 0) {
goodline = 0; /* it's bad */
break;
}
act->key_seq[j>>1] = (char)val;
}
}
act->typei = keytype_from_text(act->typen, NULL);
if (0 == act->typei) {
printf("%s: line %d: key %d, %s not supported - ignoring\n",
keyfile, line_cnt,
act->key_id, act->typen);
goodline = 0; /* it's bad */
}
}
if (goodline) {
act->next = NULL;
if (NULL == prev)
*keys = act;
else
prev->next = act;
prev = act;
key_cnt++;
} else {
if (debug) {
printf("auth_init: scanf %d items, skipping line %d.",
scan_cnt, line_cnt);
}
free(act);
}
line_cnt++;
}
fclose(keyf);
key_ptr = *keys;
return key_cnt;
}
/* Looks for the key with keyid key_id and sets the d_key pointer to the
* address of the key. If no matching key is found the pointer is not touched.
*/
void
get_key(
int key_id,
struct key **d_key
)
{
struct key *itr_key;
if (key_cnt == 0)
return;
for (itr_key = key_ptr; itr_key; itr_key = itr_key->next) {
if (itr_key->key_id == key_id) {
*d_key = itr_key;
break;
}
}
return;
}
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