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WPS: Use only os_get_random() for PIN generation

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Remove the fallback dependency on os_random() when generating a WPS pin.
This is exceptionally unlikely to ever be called as the call to
os_get_random() is unlikely to fail. The intention is to facilitate
future removal of os_random() as it uses a low quality PRNG.

Signed-off-by: Nick Lowe <nick.lowe@lugatech.com>
This commit is contained in:
Nick Lowe 2016-02-09 14:47:47 +00:00 • committed by Jouni Malinen
parent f441e5af77
commit 98a516eae8
7 changed files with 36 additions and 16 deletions
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3
src/ap/wps_hostapd.c
View file

@ -1627,7 +1627,8 @@ const char * hostapd_wps_ap_pin_random(struct hostapd_data *hapd, int timeout)
unsigned int pin;
struct wps_ap_pin_data data;
pin = wps_generate_pin();
if (wps_generate_pin(&pin) < 0)
return NULL;
os_snprintf(data.pin_txt, sizeof(data.pin_txt), "%08u", pin);
data.timeout = timeout;
hostapd_wps_for_each(hapd, wps_ap_pin_set, &data);

2
src/wps/wps.h
View file

@ -837,7 +837,7 @@ int wps_build_credential_wrap(struct wpabuf *msg,
unsigned int wps_pin_checksum(unsigned int pin);
unsigned int wps_pin_valid(unsigned int pin);
unsigned int wps_generate_pin(void);
int wps_generate_pin(unsigned int *pin);
int wps_pin_str_valid(const char *pin);
void wps_free_pending_msgs(struct upnp_pending_message *msgs);

12
src/wps/wps_common.c
View file

@ -235,20 +235,18 @@ unsigned int wps_pin_valid(unsigned int pin)
* wps_generate_pin - Generate a random PIN
* Returns: Eight digit PIN (i.e., including the checksum digit)
*/
unsigned int wps_generate_pin(void)
int wps_generate_pin(unsigned int *pin)
{
unsigned int val;
/* Generate seven random digits for the PIN */
if (random_get_bytes((unsigned char *) &val, sizeof(val)) < 0) {
struct os_time now;
os_get_time(&now);
val = os_random() ^ now.sec ^ now.usec;
}
if (random_get_bytes((unsigned char *) &val, sizeof(val)) < 0)
return -1;
val %= 10000000;
/* Append checksum digit */
return val * 10 + wps_pin_checksum(val);
*pin = val * 10 + wps_pin_checksum(val);
return 0;
}