Currently, ieee802154_random_extended_addr() has a 50% chance of
generating a group (multicast) address, while this function is used
for generating station addresses (which can't be group addresses)
for interfaces that don't have a hardware-provided address.
Also, in case get_random_bytes() generates the EUI-64 address
00:00:00:00:00:00:00:00 (extremely unlikely), which is an invalid
address, ieee802154_random_extended_addr() reacts by changing it
to 01:00:00:00:00:00:00:00, which is an invalid station address as
well, as it is a group address.
This patch changes the address generation procedure to grab eight
random bytes, treat that as an EUI-64, and then clear the Group
address bit and set the Locally Administered bit, which is in
line with how eth_random_addr() generates random EUI-48s.
Signed-off-by: Lennert Buytenhek <buytenh@xxxxxxxxxxxxxx>
---
include/linux/ieee802154.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/linux/ieee802154.h b/include/linux/ieee802154.h
index 8872ca1..552210d 100644
--- a/include/linux/ieee802154.h
+++ b/include/linux/ieee802154.h
@@ -244,9 +244,9 @@ static inline void ieee802154_random_extended_addr(__le64 *addr)
{
get_random_bytes(addr, IEEE802154_EXTENDED_ADDR_LEN);
- /* toggle some bit if we hit an invalid extended addr */
- if (!ieee802154_is_valid_extended_addr(*addr))
- ((u8 *)addr)[IEEE802154_EXTENDED_ADDR_LEN - 1] ^= 0x01;
+ /* clear the group bit, and set the locally administered bit */
+ ((u8 *)addr)[IEEE802154_EXTENDED_ADDR_LEN - 1] &= ~0x01;
+ ((u8 *)addr)[IEEE802154_EXTENDED_ADDR_LEN - 1] |= 0x02;
}
#endif /* LINUX_IEEE802154_H */
--
2.4.1
--
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