Hi Simon,
On 19/12/2020 03:29, Simon Glass wrote:
Hi Mattias,
On Wed, 16 Dec 2020 at 09:28, matthias.bgg@kernel.org wrote:
From: Matthias Brugger mbrugger@suse.com
When calculating a random UUID we use a weak seed. Use a RNG device if present to increase entropy.
Signed-off-by: Matthias Brugger mbrugger@suse.com
Changes in v2:
- fix dm_rng_read() parameters
- add missing include
lib/uuid.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-)
diff --git a/lib/uuid.c b/lib/uuid.c index e62d5ca264..e3487380c3 100644 --- a/lib/uuid.c +++ b/lib/uuid.c @@ -15,6 +15,8 @@ #include <asm/io.h> #include <part_efi.h> #include <malloc.h> +#include <dm/uclass.h> +#include <rng.h>
/*
- UUID - Universally Unique IDentifier - 128 bits unique number.
@@ -249,9 +251,22 @@ void gen_rand_uuid(unsigned char *uuid_bin) { u32 ptr[4]; struct uuid *uuid = (struct uuid *)ptr;
int i;srand(get_ticks() + rand());
int i, ret;struct udevice *devp;u8 randv = 0;+#if defined(CONFIG_DM_RNG)
This seems a little backwards to me. The caller should request a RNG device, getting either a hardware one or a software one, and then call the uclass method to get the uuid.
The problem I see here is, that in case no DM_RNG is present the seed used is different for uuid (get_ticks() + rand()) and bootp (seed_mac() uses the mac address)
So we would need to pass this alternatives to the generic DM code, which makes it a bit ugly. Apart from that beware that the seed used for srand() can vary depending on the caller and the entropy it needs.
Regards, Matthias
ret = uclass_get_device(UCLASS_RNG, 0, &devp);if (ret) {ret = dm_rng_read(devp, &randv, sizeof(randv));if (ret < 0)randv = 0;}if (randv)srand(randv);else+#endif
srand(get_ticks() + rand()); /* Set all fields randomly */ for (i = 0; i < 4; i++)-- 2.29.2
Regards, Simon