Instantiate CAAM RNG with prediction resistance enabled to improve its
quality (with PR on DRNG is forced to reseed from TRNG every time
random data is generated).
Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
Cc: Chris Healy <cphealy@xxxxxxxxx>
Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
Cc: Horia Geantă <horia.geanta@xxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Iuliana Prodan <iuliana.prodan@xxxxxxx>
Cc: linux-crypto@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-imx@xxxxxxx
---
drivers/crypto/caam/caamrng.c | 3 ++-
drivers/crypto/caam/ctrl.c | 22 ++++++++++++++++++----
drivers/crypto/caam/desc.h | 2 ++
drivers/crypto/caam/regs.h | 4 +++-
4 files changed, 25 insertions(+), 6 deletions(-)
diff --git a/drivers/crypto/caam/caamrng.c b/drivers/crypto/caam/caamrng.c
index 554aafbd4d11..91ccde0240fe 100644
--- a/drivers/crypto/caam/caamrng.c
+++ b/drivers/crypto/caam/caamrng.c
@@ -77,7 +77,8 @@ static u32 *caam_init_desc(u32 *desc, dma_addr_t dst_dma, int len)
{
init_job_desc(desc, 0); /* + 1 cmd_sz */
/* Generate random bytes: + 1 cmd_sz */
- append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG);
+ append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG |
+ OP_ALG_PR_ON);
/* Store bytes */
append_fifo_store(desc, dst_dma, len, FIFOST_TYPE_RNGSTORE);
diff --git a/drivers/crypto/caam/ctrl.c b/drivers/crypto/caam/ctrl.c
index 22d8676dd610..85c2e831839a 100644
--- a/drivers/crypto/caam/ctrl.c
+++ b/drivers/crypto/caam/ctrl.c
@@ -36,7 +36,8 @@ static void build_instantiation_desc(u32 *desc, int handle, int do_sk)
init_job_desc(desc, 0);
op_flags = OP_TYPE_CLASS1_ALG | OP_ALG_ALGSEL_RNG |
- (handle << OP_ALG_AAI_SHIFT) | OP_ALG_AS_INIT;
+ (handle << OP_ALG_AAI_SHIFT) | OP_ALG_AS_INIT |
+ OP_ALG_PR_ON;
/* INIT RNG in non-test mode */
append_operation(desc, op_flags);
@@ -275,12 +276,25 @@ static int instantiate_rng(struct device *ctrldev, int state_handle_mask,
return -ENOMEM;
for (sh_idx = 0; sh_idx < RNG4_MAX_HANDLES; sh_idx++) {
+ const u32 rdsta_if = RDSTA_IF0 << sh_idx;
+ const u32 rdsta_pr = RDSTA_PR0 << sh_idx;
+ const u32 rdsta_mask = rdsta_if | rdsta_pr;
/*
* If the corresponding bit is set, this state handle
* was initialized by somebody else, so it's left alone.
*/
- if ((1 << sh_idx) & state_handle_mask)
- continue;
+ if (rdsta_if & state_handle_mask) {
+ if (rdsta_pr & state_handle_mask)
+ continue;
+
+ dev_info(ctrldev,
+ "RNG4 SH%d was previously instantiated without prediction resistance. Tearing it down\n",
+ sh_idx);
+
+ ret = deinstantiate_rng(ctrldev, rdsta_if);
+ if (ret)
+ break;
+ }
/* Create the descriptor for instantiating RNG State Handle */
build_instantiation_desc(desc, sh_idx, gen_sk);
@@ -302,7 +316,7 @@ static int instantiate_rng(struct device *ctrldev, int state_handle_mask,
rdsta_val = rd_reg32(&ctrl->r4tst[0].rdsta) & RDSTA_IFMASK;
if ((status && status != JRSTA_SSRC_JUMP_HALT_CC) ||
- !(rdsta_val & (1 << sh_idx))) {
+ (rdsta_val & rdsta_mask) != rdsta_mask) {
ret = -EAGAIN;
break;
}
diff --git a/drivers/crypto/caam/desc.h b/drivers/crypto/caam/desc.h
index 4b6854bf896a..e796d3cb9be8 100644
--- a/drivers/crypto/caam/desc.h
+++ b/drivers/crypto/caam/desc.h
@@ -1254,6 +1254,8 @@
#define OP_ALG_ICV_OFF (0 << OP_ALG_ICV_SHIFT)
#define OP_ALG_ICV_ON (1 << OP_ALG_ICV_SHIFT)
+#define OP_ALG_PR_ON BIT(1)
+
#define OP_ALG_DIR_SHIFT 0
#define OP_ALG_DIR_MASK 1
#define OP_ALG_DECRYPT 0
diff --git a/drivers/crypto/caam/regs.h b/drivers/crypto/caam/regs.h
index c191e8fd0fa7..fe1f8c1409fd 100644
--- a/drivers/crypto/caam/regs.h
+++ b/drivers/crypto/caam/regs.h
@@ -524,9 +524,11 @@ struct rng4tst {
u32 rsvd1[40];
#define RDSTA_SKVT 0x80000000
#define RDSTA_SKVN 0x40000000
+#define RDSTA_PR0 BIT(4)
+#define RDSTA_PR1 BIT(5)
#define RDSTA_IF0 0x00000001
#define RDSTA_IF1 0x00000002
-#define RDSTA_IFMASK (RDSTA_IF1 | RDSTA_IF0)
+#define RDSTA_IFMASK (RDSTA_PR1 | RDSTA_PR0 | RDSTA_IF1 | RDSTA_IF0)
u32 rdsta;
u32 rsvd2[15];
};
--
2.21.0
