| Message ID | 20171031152524.25216-3-romain.izard.pro@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi, Romain, On 10/31/2017 05:25 PM, Romain Izard wrote: > When using the rfc4543(gcm(aes))) mode, the registers of the hardware > engine are not empty after use. If the engine is not reset before its > next use, the following results will be invalid. > > Always reset the hardware engine. Thanks for the fix! I could reproduce the issue only when running rfc4543(gcm(aes))) and then, immediately after, ecb(aes). Have you encountered this bug with other combination of algorithms? I'm trying to isolate the bug so that we can have a more fine-grained fix. Cheers, ta
2017-11-06 16:45 GMT+01:00 Tudor Ambarus <tudor.ambarus@microchip.com>: > Hi, Romain, > > On 10/31/2017 05:25 PM, Romain Izard wrote: >> >> When using the rfc4543(gcm(aes))) mode, the registers of the hardware >> engine are not empty after use. If the engine is not reset before its >> next use, the following results will be invalid. >> >> Always reset the hardware engine. > > > Thanks for the fix! I could reproduce the issue only when running > rfc4543(gcm(aes))) and then, immediately after, ecb(aes). > > Have you encountered this bug with other combination of algorithms? > > I'm trying to isolate the bug so that we can have a more fine-grained > fix. I just ran the tcrypt tests because they were failing on the cts(cbc(aes)) transform and I observed this issue when the ecb test failed only on the second run. For me, the issue looks like the rfc4543 mode does not read all the registers from the AES engine, and the following operation fails because the registers are reused directly in the ECB mode. As the ECB mode is a rare case where we do not use an IV, this may be the reason why other modes do not display the issue.
diff --git a/drivers/crypto/atmel-aes.c b/drivers/crypto/atmel-aes.c index 53432ab97d7e..024914e82734 100644 --- a/drivers/crypto/atmel-aes.c +++ b/drivers/crypto/atmel-aes.c @@ -76,12 +76,11 @@ AES_FLAGS_ENCRYPT | \ AES_FLAGS_GTAGEN) -#define AES_FLAGS_INIT BIT(2) #define AES_FLAGS_BUSY BIT(3) #define AES_FLAGS_DUMP_REG BIT(4) #define AES_FLAGS_OWN_SHA BIT(5) -#define AES_FLAGS_PERSISTENT (AES_FLAGS_INIT | AES_FLAGS_BUSY) +#define AES_FLAGS_PERSISTENT AES_FLAGS_BUSY #define ATMEL_AES_QUEUE_LENGTH 50 @@ -450,11 +449,8 @@ static int atmel_aes_hw_init(struct atmel_aes_dev *dd) if (err) return err; - if (!(dd->flags & AES_FLAGS_INIT)) { - atmel_aes_write(dd, AES_CR, AES_CR_SWRST); - atmel_aes_write(dd, AES_MR, 0xE << AES_MR_CKEY_OFFSET); - dd->flags |= AES_FLAGS_INIT; - } + atmel_aes_write(dd, AES_CR, AES_CR_SWRST); + atmel_aes_write(dd, AES_MR, 0xE << AES_MR_CKEY_OFFSET); return 0; }
When using the rfc4543(gcm(aes))) mode, the registers of the hardware engine are not empty after use. If the engine is not reset before its next use, the following results will be invalid. Always reset the hardware engine. Signed-off-by: Romain Izard <romain.izard.pro@gmail.com> --- drivers/crypto/atmel-aes.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-)