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author | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-11-19 14:42:59 +0100 |
---|---|---|
committer | Herbert Xu <herbert@gondor.apana.org.au> | 2022-11-25 17:39:19 +0800 |
commit | 83478938f78fd640c72af83d739a90c840e1b876 (patch) | |
tree | 0a032db4ffb45ba23d76f84d798589821993a6dd /drivers/hid | |
parent | 5f9c97a0e6dc873f662528ae591f2bd500eb5940 (diff) | |
download | linux-stable-83478938f78fd640c72af83d739a90c840e1b876.tar.gz linux-stable-83478938f78fd640c72af83d739a90c840e1b876.tar.bz2 linux-stable-83478938f78fd640c72af83d739a90c840e1b876.zip |
hwrng: u2fzero - account for high quality RNG
The U2F zero apparently has a real TRNG in it with maximum quality, not
one with quality of "1", which was likely a misinterpretation of the
field as a boolean. So remove the assignment entirely, so that we get
the default quality setting.
In the u2f-zero firmware, the 0x21 RNG command used by this driver is
handled as such [1]:
case U2F_CUSTOM_GET_RNG:
if (atecc_send_recv(ATECC_CMD_RNG,ATECC_RNG_P1,ATECC_RNG_P2,
NULL, 0,
appdata.tmp,
sizeof(appdata.tmp), &res) == 0 )
{
memmove(msg->pkt.init.payload, res.buf, 32);
U2FHID_SET_LEN(msg, 32);
usb_write((uint8_t*)msg, 64);
}
else
{
U2FHID_SET_LEN(msg, 0);
usb_write((uint8_t*)msg, 64);
}
This same call to `atecc_send_recv(ATECC_CMD_RNG,ATECC_RNG_P1,
ATECC_RNG_P2,...)` is then also used in the token's cryptographically
critical "u2f_new_keypair" function, as its rather straightforward
source of random bytes [2]:
int8_t u2f_new_keypair(uint8_t * handle, uint8_t * appid, uint8_t * pubkey)
{
struct atecc_response res;
uint8_t private_key[36];
int i;
watchdog();
if (atecc_send_recv(ATECC_CMD_RNG,ATECC_RNG_P1,ATECC_RNG_P2,
NULL, 0,
appdata.tmp,
sizeof(appdata.tmp), &res) != 0 )
{
return -1;
}
So it seems rather plain that the ATECC RNG is considered to provide
good random numbers.
[1] https://github.com/conorpp/u2f-zero/blob/master/firmware/src/custom.c
[2] https://github.com/conorpp/u2f-zero/blob/master/firmware/src/u2f_atecc.c
Cc: Andrej Shadura <andrew.shadura@collabora.co.uk>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Acked-by: Andrej Shadura <andrew.shadura@collabora.co.uk>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'drivers/hid')
-rw-r--r-- | drivers/hid/hid-u2fzero.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/drivers/hid/hid-u2fzero.c b/drivers/hid/hid-u2fzero.c index ad489caf53ad..744a91e6e78c 100644 --- a/drivers/hid/hid-u2fzero.c +++ b/drivers/hid/hid-u2fzero.c @@ -261,7 +261,6 @@ static int u2fzero_init_hwrng(struct u2fzero_device *dev, dev->hwrng.name = dev->rng_name; dev->hwrng.read = u2fzero_rng_read; - dev->hwrng.quality = 1; return devm_hwrng_register(&dev->hdev->dev, &dev->hwrng); } |