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crypto: tcrypt - Remove VLA usage
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In the quest to remove all stack VLA usage from the kernel[1], this
allocates the return code buffers before starting jiffie timers, rather
than using stack space for the array. Additionally cleans up some exit
paths and make sure that the num_mb module_param() is used only once
per execution to avoid possible races in the value changing.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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Kees Cook authored and Herbert Xu committed May 5, 2018
1 parent e99ce92 commit 4e234ee
Showing 1 changed file with 79 additions and 39 deletions.
118 changes: 79 additions & 39 deletions crypto/tcrypt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -158,9 +158,9 @@ struct test_mb_aead_data {
};

static int do_mult_aead_op(struct test_mb_aead_data *data, int enc,
u32 num_mb)
u32 num_mb, int *rc)
{
int i, rc[num_mb], err = 0;
int i, err = 0;

/* Fire up a bunch of concurrent requests */
for (i = 0; i < num_mb; i++) {
Expand Down Expand Up @@ -188,18 +188,26 @@ static int test_mb_aead_jiffies(struct test_mb_aead_data *data, int enc,
{
unsigned long start, end;
int bcount;
int ret;
int ret = 0;
int *rc;

rc = kcalloc(num_mb, sizeof(*rc), GFP_KERNEL);
if (!rc)
return -ENOMEM;

for (start = jiffies, end = start + secs * HZ, bcount = 0;
time_before(jiffies, end); bcount++) {
ret = do_mult_aead_op(data, enc, num_mb);
ret = do_mult_aead_op(data, enc, num_mb, rc);
if (ret)
return ret;
goto out;
}

pr_cont("%d operations in %d seconds (%ld bytes)\n",
bcount * num_mb, secs, (long)bcount * blen * num_mb);
return 0;

out:
kfree(rc);
return ret;
}

static int test_mb_aead_cycles(struct test_mb_aead_data *data, int enc,
Expand All @@ -208,10 +216,15 @@ static int test_mb_aead_cycles(struct test_mb_aead_data *data, int enc,
unsigned long cycles = 0;
int ret = 0;
int i;
int *rc;

rc = kcalloc(num_mb, sizeof(*rc), GFP_KERNEL);
if (!rc)
return -ENOMEM;

/* Warm-up run. */
for (i = 0; i < 4; i++) {
ret = do_mult_aead_op(data, enc, num_mb);
ret = do_mult_aead_op(data, enc, num_mb, rc);
if (ret)
goto out;
}
Expand All @@ -221,7 +234,7 @@ static int test_mb_aead_cycles(struct test_mb_aead_data *data, int enc,
cycles_t start, end;

start = get_cycles();
ret = do_mult_aead_op(data, enc, num_mb);
ret = do_mult_aead_op(data, enc, num_mb, rc);
end = get_cycles();

if (ret)
Expand All @@ -230,11 +243,11 @@ static int test_mb_aead_cycles(struct test_mb_aead_data *data, int enc,
cycles += end - start;
}

out:
if (ret == 0)
pr_cont("1 operation in %lu cycles (%d bytes)\n",
(cycles + 4) / (8 * num_mb), blen);
pr_cont("1 operation in %lu cycles (%d bytes)\n",
(cycles + 4) / (8 * num_mb), blen);

out:
kfree(rc);
return ret;
}

Expand Down Expand Up @@ -705,9 +718,10 @@ struct test_mb_ahash_data {
char *xbuf[XBUFSIZE];
};

static inline int do_mult_ahash_op(struct test_mb_ahash_data *data, u32 num_mb)
static inline int do_mult_ahash_op(struct test_mb_ahash_data *data, u32 num_mb,
int *rc)
{
int i, rc[num_mb], err = 0;
int i, err = 0;

/* Fire up a bunch of concurrent requests */
for (i = 0; i < num_mb; i++)
Expand All @@ -731,18 +745,26 @@ static int test_mb_ahash_jiffies(struct test_mb_ahash_data *data, int blen,
{
unsigned long start, end;
int bcount;
int ret;
int ret = 0;
int *rc;

rc = kcalloc(num_mb, sizeof(*rc), GFP_KERNEL);
if (!rc)
return -ENOMEM;

for (start = jiffies, end = start + secs * HZ, bcount = 0;
time_before(jiffies, end); bcount++) {
ret = do_mult_ahash_op(data, num_mb);
ret = do_mult_ahash_op(data, num_mb, rc);
if (ret)
return ret;
goto out;
}

pr_cont("%d operations in %d seconds (%ld bytes)\n",
bcount * num_mb, secs, (long)bcount * blen * num_mb);
return 0;

out:
kfree(rc);
return ret;
}

static int test_mb_ahash_cycles(struct test_mb_ahash_data *data, int blen,
Expand All @@ -751,10 +773,15 @@ static int test_mb_ahash_cycles(struct test_mb_ahash_data *data, int blen,
unsigned long cycles = 0;
int ret = 0;
int i;
int *rc;

rc = kcalloc(num_mb, sizeof(*rc), GFP_KERNEL);
if (!rc)
return -ENOMEM;

/* Warm-up run. */
for (i = 0; i < 4; i++) {
ret = do_mult_ahash_op(data, num_mb);
ret = do_mult_ahash_op(data, num_mb, rc);
if (ret)
goto out;
}
Expand All @@ -764,7 +791,7 @@ static int test_mb_ahash_cycles(struct test_mb_ahash_data *data, int blen,
cycles_t start, end;

start = get_cycles();
ret = do_mult_ahash_op(data, num_mb);
ret = do_mult_ahash_op(data, num_mb, rc);
end = get_cycles();

if (ret)
Expand All @@ -773,11 +800,11 @@ static int test_mb_ahash_cycles(struct test_mb_ahash_data *data, int blen,
cycles += end - start;
}

out:
if (ret == 0)
pr_cont("1 operation in %lu cycles (%d bytes)\n",
(cycles + 4) / (8 * num_mb), blen);
pr_cont("1 operation in %lu cycles (%d bytes)\n",
(cycles + 4) / (8 * num_mb), blen);

out:
kfree(rc);
return ret;
}

Expand Down Expand Up @@ -1118,9 +1145,9 @@ struct test_mb_skcipher_data {
};

static int do_mult_acipher_op(struct test_mb_skcipher_data *data, int enc,
u32 num_mb)
u32 num_mb, int *rc)
{
int i, rc[num_mb], err = 0;
int i, err = 0;

/* Fire up a bunch of concurrent requests */
for (i = 0; i < num_mb; i++) {
Expand Down Expand Up @@ -1148,18 +1175,26 @@ static int test_mb_acipher_jiffies(struct test_mb_skcipher_data *data, int enc,
{
unsigned long start, end;
int bcount;
int ret;
int ret = 0;
int *rc;

rc = kcalloc(num_mb, sizeof(*rc), GFP_KERNEL);
if (!rc)
return -ENOMEM;

for (start = jiffies, end = start + secs * HZ, bcount = 0;
time_before(jiffies, end); bcount++) {
ret = do_mult_acipher_op(data, enc, num_mb);
ret = do_mult_acipher_op(data, enc, num_mb, rc);
if (ret)
return ret;
goto out;
}

pr_cont("%d operations in %d seconds (%ld bytes)\n",
bcount * num_mb, secs, (long)bcount * blen * num_mb);
return 0;

out:
kfree(rc);
return ret;
}

static int test_mb_acipher_cycles(struct test_mb_skcipher_data *data, int enc,
Expand All @@ -1168,10 +1203,15 @@ static int test_mb_acipher_cycles(struct test_mb_skcipher_data *data, int enc,
unsigned long cycles = 0;
int ret = 0;
int i;
int *rc;

rc = kcalloc(num_mb, sizeof(*rc), GFP_KERNEL);
if (!rc)
return -ENOMEM;

/* Warm-up run. */
for (i = 0; i < 4; i++) {
ret = do_mult_acipher_op(data, enc, num_mb);
ret = do_mult_acipher_op(data, enc, num_mb, rc);
if (ret)
goto out;
}
Expand All @@ -1181,7 +1221,7 @@ static int test_mb_acipher_cycles(struct test_mb_skcipher_data *data, int enc,
cycles_t start, end;

start = get_cycles();
ret = do_mult_acipher_op(data, enc, num_mb);
ret = do_mult_acipher_op(data, enc, num_mb, rc);
end = get_cycles();

if (ret)
Expand All @@ -1190,11 +1230,11 @@ static int test_mb_acipher_cycles(struct test_mb_skcipher_data *data, int enc,
cycles += end - start;
}

out:
if (ret == 0)
pr_cont("1 operation in %lu cycles (%d bytes)\n",
(cycles + 4) / (8 * num_mb), blen);
pr_cont("1 operation in %lu cycles (%d bytes)\n",
(cycles + 4) / (8 * num_mb), blen);

out:
kfree(rc);
return ret;
}

Expand Down Expand Up @@ -1606,7 +1646,7 @@ static inline int tcrypt_test(const char *alg)
return ret;
}

static int do_test(const char *alg, u32 type, u32 mask, int m)
static int do_test(const char *alg, u32 type, u32 mask, int m, u32 num_mb)
{
int i;
int ret = 0;
Expand All @@ -1621,7 +1661,7 @@ static int do_test(const char *alg, u32 type, u32 mask, int m)
}

for (i = 1; i < 200; i++)
ret += do_test(NULL, 0, 0, i);
ret += do_test(NULL, 0, 0, i, num_mb);
break;

case 1:
Expand Down Expand Up @@ -2903,7 +2943,7 @@ static int __init tcrypt_mod_init(void)
goto err_free_tv;
}

err = do_test(alg, type, mask, mode);
err = do_test(alg, type, mask, mode, num_mb);

if (err) {
printk(KERN_ERR "tcrypt: one or more tests failed!\n");
Expand Down

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