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crypto: crypto4xx - Remove insecure and unused rng_alg

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Remove crypto4xx_rng, as it is insecure and unused:

- It has only a 64-bit security strength, which is highly inadequate.
  This can be seen by the fact that crypto4xx_hw_init() seeds it with
  only 64 bits of entropy, and the fact that the original commit
  mentions that it implements ANSI X9.17 Annex C.

  Another issue was that this driver didn't implement the crypto_rng API
  correctly, as crypto4xx_prng_generate() didn't return 0 on success.

- No user of this code is known.  It's usable only theoretically via the
  "rng" algorithm type of AF_ALG.  But userspace actually just uses the
  actual Linux RNG (/dev/random etc) instead.  And rng_algs don't
  contribute entropy to the actual Linux RNG either.  (This may have
  been confused with hwrng, which does contribute entropy.)

Fixes: d072bfa488 ("crypto: crypto4xx - add prng crypto support")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Acked-by: Christian Lamparter <chunkeey@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Eric Biggers
2026-05-29 15:04:30 -07:00
committed by Herbert Xu
parent b3ac787565
commit 7811ec9e97
4 changed files with 0 additions and 104 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/crypto/Kconfig
View File

@@ -301,7 +301,6 @@ config CRYPTO_DEV_PPC4XX
select CRYPTO_CCM
select CRYPTO_CTR
select CRYPTO_GCM
select CRYPTO_RNG
select CRYPTO_SKCIPHER
help
This option allows you to have support for AMCC crypto acceleration.

88
drivers/crypto/amcc/crypto4xx_core.c
View File

@@ -31,11 +31,9 @@
#include <crypto/ctr.h>
#include <crypto/gcm.h>
#include <crypto/sha1.h>
#include <crypto/rng.h>
#include <crypto/scatterwalk.h>
#include <crypto/skcipher.h>
#include <crypto/internal/aead.h>
#include <crypto/internal/rng.h>
#include <crypto/internal/skcipher.h>
#include "crypto4xx_reg_def.h"
#include "crypto4xx_core.h"
@@ -985,10 +983,6 @@ static int crypto4xx_register_alg(struct crypto4xx_device *sec_dev,
rc = crypto_register_aead(&alg->alg.u.aead);
break;
case CRYPTO_ALG_TYPE_RNG:
rc = crypto_register_rng(&alg->alg.u.rng);
break;
default:
rc = crypto_register_skcipher(&alg->alg.u.cipher);
break;
@@ -1014,10 +1008,6 @@ static void crypto4xx_unregister_alg(struct crypto4xx_device *sec_dev)
crypto_unregister_aead(&alg->alg.u.aead);
break;
case CRYPTO_ALG_TYPE_RNG:
crypto_unregister_rng(&alg->alg.u.rng);
break;
default:
crypto_unregister_skcipher(&alg->alg.u.cipher);
}
@@ -1076,69 +1066,6 @@ static irqreturn_t crypto4xx_ce_interrupt_handler_revb(int irq, void *data)
PPC4XX_TMO_ERR_INT);
}
static int ppc4xx_prng_data_read(struct crypto4xx_device *dev,
u8 *data, unsigned int max)
{
unsigned int i, curr = 0;
u32 val[2];
do {
/* trigger PRN generation */
writel(PPC4XX_PRNG_CTRL_AUTO_EN,
dev->ce_base + CRYPTO4XX_PRNG_CTRL);
for (i = 0; i < 1024; i++) {
/* usually 19 iterations are enough */
if ((readl(dev->ce_base + CRYPTO4XX_PRNG_STAT) &
CRYPTO4XX_PRNG_STAT_BUSY))
continue;
val[0] = readl_be(dev->ce_base + CRYPTO4XX_PRNG_RES_0);
val[1] = readl_be(dev->ce_base + CRYPTO4XX_PRNG_RES_1);
break;
}
if (i == 1024)
return -ETIMEDOUT;
if ((max - curr) >= 8) {
memcpy(data, &val, 8);
data += 8;
curr += 8;
} else {
/* copy only remaining bytes */
memcpy(data, &val, max - curr);
break;
}
} while (curr < max);
return curr;
}
static int crypto4xx_prng_generate(struct crypto_rng *tfm,
const u8 *src, unsigned int slen,
u8 *dstn, unsigned int dlen)
{
struct rng_alg *alg = crypto_rng_alg(tfm);
struct crypto4xx_alg *amcc_alg;
struct crypto4xx_device *dev;
int ret;
amcc_alg = container_of(alg, struct crypto4xx_alg, alg.u.rng);
dev = amcc_alg->dev;
mutex_lock(&dev->core_dev->rng_lock);
ret = ppc4xx_prng_data_read(dev, dstn, dlen);
mutex_unlock(&dev->core_dev->rng_lock);
return ret;
}
static int crypto4xx_prng_seed(struct crypto_rng *tfm, const u8 *seed,
unsigned int slen)
{
return 0;
}
/*
* Supported Crypto Algorithms
*/
@@ -1268,18 +1195,6 @@ static struct crypto4xx_alg_common crypto4xx_alg[] = {
.cra_module = THIS_MODULE,
},
} },
{ .type = CRYPTO_ALG_TYPE_RNG, .u.rng = {
.base = {
.cra_name = "stdrng",
.cra_driver_name = "crypto4xx_rng",
.cra_priority = 300,
.cra_ctxsize = 0,
.cra_module = THIS_MODULE,
},
.generate = crypto4xx_prng_generate,
.seed = crypto4xx_prng_seed,
.seedsize = 0,
} },
};
/*
@@ -1353,9 +1268,6 @@ static int crypto4xx_probe(struct platform_device *ofdev)
core_dev->dev->core_dev = core_dev;
core_dev->dev->is_revb = is_revb;
core_dev->device = dev;
rc = devm_mutex_init(&ofdev->dev, &core_dev->rng_lock);
if (rc)
return rc;
spin_lock_init(&core_dev->lock);
INIT_LIST_HEAD(&core_dev->dev->alg_list);
ratelimit_default_init(&core_dev->dev->aead_ratelimit);

4
drivers/crypto/amcc/crypto4xx_core.h
View File

@@ -14,10 +14,8 @@
#define __CRYPTO4XX_CORE_H__
#include <linux/ratelimit.h>
#include <linux/mutex.h>
#include <linux/scatterlist.h>
#include <crypto/internal/aead.h>
#include <crypto/internal/rng.h>
#include <crypto/internal/skcipher.h>
#include "crypto4xx_reg_def.h"
#include "crypto4xx_sa.h"
@@ -111,7 +109,6 @@ struct crypto4xx_core_device {
u32 irq;
struct tasklet_struct tasklet;
spinlock_t lock;
struct mutex rng_lock;
};
struct crypto4xx_ctx {
@@ -135,7 +132,6 @@ struct crypto4xx_alg_common {
union {
struct skcipher_alg cipher;
struct aead_alg aead;
struct rng_alg rng;
} u;
};

11
drivers/crypto/amcc/crypto4xx_reg_def.h
View File

@@ -90,20 +90,9 @@
#define CRYPTO4XX_BYTE_ORDER_CFG 0x000600d8
#define CRYPTO4XX_ENDIAN_CFG 0x000600d8
#define CRYPTO4XX_PRNG_STAT 0x00070000
#define CRYPTO4XX_PRNG_STAT_BUSY 0x1
#define CRYPTO4XX_PRNG_CTRL 0x00070004
#define CRYPTO4XX_PRNG_SEED_L 0x00070008
#define CRYPTO4XX_PRNG_SEED_H 0x0007000c
#define CRYPTO4XX_PRNG_RES_0 0x00070020
#define CRYPTO4XX_PRNG_RES_1 0x00070024
#define CRYPTO4XX_PRNG_RES_2 0x00070028
#define CRYPTO4XX_PRNG_RES_3 0x0007002C
#define CRYPTO4XX_PRNG_LFSR_L 0x00070030
#define CRYPTO4XX_PRNG_LFSR_H 0x00070034
/*
* Initialize CRYPTO ENGINE registers, and memory bases.
*/