crypto: xilinx-trng - Remove crypto_rng interface

Implementing the crypto_rng interface has no purpose, as it isn't used
in practice.  It's being removed from other drivers too.  Just remove
it.  This leaves hwrng, which is actually used.

Tagging with 'Cc stable' due to the bugs that this removes:

  - xtrng_trng_generate() sometimes returned success even when it didn't
    fill in all the bytes.

  - It was possible for xtrng_trng_generate() and
    xtrng_hwrng_trng_read() to run concurrently and interfere with each
    other, as the locking code in xtrng_hwrng_trng_read() was broken.

Fixes: 8979744aca80 ("crypto: xilinx - Add TRNG driver for Versal")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/crypto/Kconfig b/drivers/crypto/Kconfig
index 4c47ab6bb26796829e5c396e20cd639bff5ef6bc..851904fb9ba49739868b53d0f406f6506251caa2 100644 (file)
--- a/drivers/crypto/Kconfig
+++ b/drivers/crypto/Kconfig
@@ -703,7 +703,6 @@ config CRYPTO_DEV_XILINX_TRNG
        tristate "Support for Xilinx True Random Generator"
        depends on ZYNQMP_FIRMWARE || COMPILE_TEST
        select CRYPTO_DF80090A
-       select CRYPTO_RNG
        select HW_RANDOM
        help
          Xilinx Versal SoC driver provides kernel-side support for True Random Number

diff --git a/drivers/crypto/xilinx/xilinx-trng.c b/drivers/crypto/xilinx/xilinx-trng.c
index 43a4832f07e7ddefdcc752c67eeb9b883c5bb088..a35643baa4899869a7597a04fa83243dbf56cbbf 100644 (file)
--- a/drivers/crypto/xilinx/xilinx-trng.c
+++ b/drivers/crypto/xilinx/xilinx-trng.c
@@ -6,7 +6,6 @@
 
 #include <linux/bitfield.h>
 #include <linux/clk.h>
-#include <linux/crypto.h>
 #include <linux/delay.h>
 #include <linux/firmware/xlnx-zynqmp.h>
 #include <linux/hw_random.h>
@@ -14,13 +13,11 @@
 #include <linux/iopoll.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/mutex.h>
 #include <linux/mod_devicetable.h>
 #include <linux/platform_device.h>
 #include <crypto/aes.h>
 #include <crypto/df_sp80090a.h>
 #include <crypto/internal/cipher.h>
-#include <crypto/internal/rng.h>
 
 /* TRNG Registers Offsets */
 #define TRNG_STATUS_OFFSET                     0x4U
@@ -60,16 +57,9 @@ struct xilinx_rng {
        struct device *dev;
        unsigned char *scratchpadbuf;
        struct aes_enckey *aeskey;
-       struct mutex lock;      /* Protect access to TRNG device */
        struct hwrng trng;
 };
 
-struct xilinx_rng_ctx {
-       struct xilinx_rng *rng;
-};
-
-static struct xilinx_rng *xilinx_rng_dev;
-
 static void xtrng_readwrite32(void __iomem *addr, u32 mask, u8 value)
 {
        u32 val;
@@ -245,47 +235,6 @@ static int xtrng_random_bytes_generate(struct xilinx_rng *rng, u8 *rand_buf_ptr,
        return nbytes;
 }
 
-static int xtrng_trng_generate(struct crypto_rng *tfm, const u8 *src, u32 slen,
-                              u8 *dst, u32 dlen)
-{
-       struct xilinx_rng_ctx *ctx = crypto_rng_ctx(tfm);
-       int ret;
-
-       mutex_lock(&ctx->rng->lock);
-       ret = xtrng_random_bytes_generate(ctx->rng, dst, dlen, true);
-       mutex_unlock(&ctx->rng->lock);
-
-       return ret < 0 ? ret : 0;
-}
-
-static int xtrng_trng_seed(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
-{
-       return 0;
-}
-
-static int xtrng_trng_init(struct crypto_tfm *rtfm)
-{
-       struct xilinx_rng_ctx *ctx = crypto_tfm_ctx(rtfm);
-
-       ctx->rng = xilinx_rng_dev;
-
-       return 0;
-}
-
-static struct rng_alg xtrng_trng_alg = {
-       .generate = xtrng_trng_generate,
-       .seed = xtrng_trng_seed,
-       .seedsize = 0,
-       .base = {
-               .cra_name = "stdrng",
-               .cra_driver_name = "xilinx-trng",
-               .cra_priority = 300,
-               .cra_ctxsize = sizeof(struct xilinx_rng_ctx),
-               .cra_module = THIS_MODULE,
-               .cra_init = xtrng_trng_init,
-       },
-};
-
 static int xtrng_hwrng_trng_read(struct hwrng *hwrng, void *data, size_t max, bool wait)
 {
        u8 buf[TRNG_SEC_STRENGTH_BYTES];
@@ -293,12 +242,6 @@ static int xtrng_hwrng_trng_read(struct hwrng *hwrng, void *data, size_t max, bo
        int ret = -EINVAL, i = 0;
 
        rng = container_of(hwrng, struct xilinx_rng, trng);
-       /* Return in case wait not set and lock not available. */
-       if (!mutex_trylock(&rng->lock) && !wait)
-               return 0;
-       else if (!mutex_is_locked(&rng->lock) && wait)
-               mutex_lock(&rng->lock);
-
        while (i < max) {
                ret = xtrng_random_bytes_generate(rng, buf, TRNG_SEC_STRENGTH_BYTES, wait);
                if (ret < 0)
@@ -307,8 +250,6 @@ static int xtrng_hwrng_trng_read(struct hwrng *hwrng, void *data, size_t max, bo
                memcpy(data + i, buf, min_t(int, ret, (max - i)));
                i += min_t(int, ret, (max - i));
        }
-       mutex_unlock(&rng->lock);
-
        return ret;
 }
 
@@ -354,40 +295,24 @@ static int xtrng_probe(struct platform_device *pdev)
 
        sb_size = crypto_drbg_ctr_df_datalen(TRNG_SEED_LEN_BYTES, AES_BLOCK_SIZE);
        rng->scratchpadbuf = devm_kzalloc(&pdev->dev, sb_size, GFP_KERNEL);
-       if (!rng->scratchpadbuf) {
-               ret = -ENOMEM;
-               goto end;
-       }
+       if (!rng->scratchpadbuf)
+               return -ENOMEM;
 
        xtrng_trng_reset(rng->rng_base);
        ret = xtrng_reseed_internal(rng);
        if (ret) {
                dev_err(&pdev->dev, "TRNG Seed fail\n");
-               goto end;
-       }
-
-       xilinx_rng_dev = rng;
-       mutex_init(&rng->lock);
-       ret = crypto_register_rng(&xtrng_trng_alg);
-       if (ret) {
-               dev_err(&pdev->dev, "Crypto Random device registration failed: %d\n", ret);
-               goto end;
+               return ret;
        }
 
        ret = xtrng_hwrng_register(&rng->trng);
        if (ret) {
                dev_err(&pdev->dev, "HWRNG device registration failed: %d\n", ret);
-               goto crypto_rng_free;
+               return ret;
        }
        platform_set_drvdata(pdev, rng);
 
        return 0;
-
-crypto_rng_free:
-       crypto_unregister_rng(&xtrng_trng_alg);
-
-end:
-       return ret;
 }
 
 static void xtrng_remove(struct platform_device *pdev)
@@ -397,13 +322,11 @@ static void xtrng_remove(struct platform_device *pdev)
 
        rng = platform_get_drvdata(pdev);
        xtrng_hwrng_unregister(&rng->trng);
-       crypto_unregister_rng(&xtrng_trng_alg);
        xtrng_write_multiple_registers(rng->rng_base + TRNG_EXT_SEED_OFFSET, zero,
                                       TRNG_NUM_INIT_REGS);
        xtrng_write_multiple_registers(rng->rng_base + TRNG_PER_STRNG_OFFSET, zero,
                                       TRNG_NUM_INIT_REGS);
        xtrng_hold_reset(rng->rng_base);
-       xilinx_rng_dev = NULL;
 }
 
 static const struct of_device_id xtrng_of_match[] = {