[PATCH v2] crypto: x86/polyval - Fix crashes when keys are not 16-byte aligned

Nathan Huckleberry
2022-10-18T21:56:43Z

crypto_tfm::__crt_ctx is not guaranteed to be 16-byte aligned on x86-64.
This causes crashes due to movaps instructions in clmul_polyval_update.

Add logic to align polyval_tfm_ctx to 16 bytes if required.

Fixes: 34f7f6c30112 ("crypto: x86/polyval - Add PCLMULQDQ accelerated implementation of POLYVAL")
Reported-by: Bruno Goncalves <bgoncalv@redhat.com>
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
---
arch/x86/crypto/polyval-clmulni_glue.c | 29 ++++++++++++++++++++------
1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/arch/x86/crypto/polyval-clmulni_glue.c b/arch/x86/crypto/polyval-clmulni_glue.c
index b7664d018851..79ad497c32b5 100644
--- a/arch/x86/crypto/polyval-clmulni_glue.c
+++ b/arch/x86/crypto/polyval-clmulni_glue.c
@@ -27,13 +27,17 @@
#include <asm/cpu_device_id.h>
#include <asm/simd.h>

+#define POLYVAL_ALIGN 16
+#define POLYVAL_ALIGN_ATTR __aligned(POLYVAL_ALIGN)
+#define POLYVAL_ALIGN_EXTRA ((POLYVAL_ALIGN - 1) & ~(CRYPTO_MINALIGN - 1))
+#define POLYVAL_CTX_SIZE (sizeof(struct polyval_tfm_ctx) + POLYVAL_ALIGN_EXTRA)
#define NUM_KEY_POWERS 8

struct polyval_tfm_ctx {
/*
* These powers must be in the order h^8, ..., h^1.
*/
- u8 key_powers[NUM_KEY_POWERS][POLYVAL_BLOCK_SIZE];
+ u8 key_powers[NUM_KEY_POWERS][POLYVAL_BLOCK_SIZE] POLYVAL_ALIGN_ATTR;
};

struct polyval_desc_ctx {
@@ -45,9 +49,20 @@ asmlinkage void clmul_polyval_update(const struct polyval_tfm_ctx *keys,
const u8 *in, size_t nblocks, u8 *accumulator);
asmlinkage void clmul_polyval_mul(u8 *op1, const u8 *op2);

-static void internal_polyval_update(const struct polyval_tfm_ctx *keys,
+static inline struct polyval_tfm_ctx *polyval_tfm_ctx(const void *raw_ctx)
+{
+ unsigned long addr = (unsigned long)raw_ctx;
+ unsigned long align = POLYVAL_ALIGN;
+
+ if (align <= crypto_tfm_ctx_alignment())
+ align = 1;
+ return (struct polyval_tfm_ctx *)ALIGN(addr, align);
+}
+
+static void internal_polyval_update(const void *raw_keys,
const u8 *in, size_t nblocks, u8 *accumulator)
{
+ const struct polyval_tfm_ctx *keys = polyval_tfm_ctx(raw_keys);
if (likely(crypto_simd_usable())) {
kernel_fpu_begin();
clmul_polyval_update(keys, in, nblocks, accumulator);
@@ -72,7 +87,7 @@ static void internal_polyval_mul(u8 *op1, const u8 *op2)
static int polyval_x86_setkey(struct crypto_shash *tfm,
const u8 *key, unsigned int keylen)
{
- struct polyval_tfm_ctx *tctx = crypto_shash_ctx(tfm);
+ struct polyval_tfm_ctx *tctx = polyval_tfm_ctx(crypto_shash_ctx(tfm));
int i;

if (keylen != POLYVAL_BLOCK_SIZE)
@@ -102,7 +117,8 @@ static int polyval_x86_update(struct shash_desc *desc,
const u8 *src, unsigned int srclen)
{
struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
- const struct polyval_tfm_ctx *tctx = crypto_shash_ctx(desc->tfm);
+ const struct polyval_tfm_ctx *tctx =
+ polyval_tfm_ctx(crypto_shash_ctx(desc->tfm));
u8 *pos;
unsigned int nblocks;
unsigned int n;
@@ -143,7 +159,8 @@ static int polyval_x86_update(struct shash_desc *desc,
static int polyval_x86_final(struct shash_desc *desc, u8 *dst)
{
struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
- const struct polyval_tfm_ctx *tctx = crypto_shash_ctx(desc->tfm);
+ const struct polyval_tfm_ctx *tctx =
+ polyval_tfm_ctx(crypto_shash_ctx(desc->tfm));

if (dctx->bytes) {
internal_polyval_mul(dctx->buffer,
@@ -167,7 +184,7 @@ static struct shash_alg polyval_alg = {
.cra_driver_name = "polyval-clmulni",
.cra_priority = 200,
.cra_blocksize = POLYVAL_BLOCK_SIZE,
- .cra_ctxsize = sizeof(struct polyval_tfm_ctx),
+ .cra_ctxsize = POLYVAL_CTX_SIZE,
.cra_module = THIS_MODULE,
},
};
--
2.38.0.413.g74048e4d9e-goog