* [PATCH] ppp: mppe: Remove VLA usage
@ 2018-07-16 4:05 ` Kees Cook
0 siblings, 0 replies; 10+ messages in thread
From: Kees Cook @ 2018-07-16 4:05 UTC (permalink / raw)
To: Paul Mackerras, David S. Miller
Cc: Herbert Xu, Arnd Bergmann, Eric Biggers, Gustavo A. R. Silva,
linux-ppp, netdev, linux-kernel
In the quest to remove all stack VLA usage from the kernel[1], this
removes the discouraged use of AHASH_REQUEST_ON_STACK (and associated
VLA) by switching to shash directly and keeping the associated descriptor
allocated with the regular state on the heap.
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/net/ppp/ppp_mppe.c | 57 +++++++++++++++++++++-----------------
1 file changed, 31 insertions(+), 26 deletions(-)
diff --git a/drivers/net/ppp/ppp_mppe.c b/drivers/net/ppp/ppp_mppe.c
index 6c7fd98cb00a..5b4b81027a75 100644
--- a/drivers/net/ppp/ppp_mppe.c
+++ b/drivers/net/ppp/ppp_mppe.c
@@ -96,7 +96,7 @@ static inline void sha_pad_init(struct sha_pad *shapad)
*/
struct ppp_mppe_state {
struct crypto_skcipher *arc4;
- struct crypto_ahash *sha1;
+ struct shash_desc *sha1;
unsigned char *sha1_digest;
unsigned char master_key[MPPE_MAX_KEY_LEN];
unsigned char session_key[MPPE_MAX_KEY_LEN];
@@ -136,25 +136,16 @@ struct ppp_mppe_state {
*/
static void get_new_key_from_sha(struct ppp_mppe_state * state)
{
- AHASH_REQUEST_ON_STACK(req, state->sha1);
- struct scatterlist sg[4];
- unsigned int nbytes;
-
- sg_init_table(sg, 4);
-
- nbytes = setup_sg(&sg[0], state->master_key, state->keylen);
- nbytes += setup_sg(&sg[1], sha_pad->sha_pad1,
- sizeof(sha_pad->sha_pad1));
- nbytes += setup_sg(&sg[2], state->session_key, state->keylen);
- nbytes += setup_sg(&sg[3], sha_pad->sha_pad2,
- sizeof(sha_pad->sha_pad2));
-
- ahash_request_set_tfm(req, state->sha1);
- ahash_request_set_callback(req, 0, NULL, NULL);
- ahash_request_set_crypt(req, sg, state->sha1_digest, nbytes);
-
- crypto_ahash_digest(req);
- ahash_request_zero(req);
+ crypto_shash_init(state->sha1);
+ crypto_shash_update(state->sha1, state->master_key,
+ state->keylen);
+ crypto_shash_update(state->sha1, sha_pad->sha_pad1,
+ sizeof(sha_pad->sha_pad1));
+ crypto_shash_update(state->sha1, state->session_key,
+ state->keylen);
+ crypto_shash_update(state->sha1, sha_pad->sha_pad2,
+ sizeof(sha_pad->sha_pad2));
+ crypto_shash_final(state->sha1, state->sha1_digest);
}
/*
@@ -200,6 +191,7 @@ static void mppe_rekey(struct ppp_mppe_state * state, int initial_key)
static void *mppe_alloc(unsigned char *options, int optlen)
{
struct ppp_mppe_state *state;
+ struct crypto_shash *shash;
unsigned int digestsize;
if (optlen != CILEN_MPPE + sizeof(state->master_key) ||
@@ -217,13 +209,21 @@ static void *mppe_alloc(unsigned char *options, int optlen)
goto out_free;
}
- state->sha1 = crypto_alloc_ahash("sha1", 0, CRYPTO_ALG_ASYNC);
- if (IS_ERR(state->sha1)) {
- state->sha1 = NULL;
+ shash = crypto_alloc_shash("sha1", 0, 0);
+ if (IS_ERR(shash))
+ goto out_free;
+
+ state->sha1 = kmalloc(sizeof(*state->sha1) +
+ crypto_shash_descsize(shash),
+ GFP_KERNEL);
+ if (!state->sha1) {
+ crypto_free_shash(shash);
goto out_free;
}
+ state->sha1->tfm = shash;
+ state->sha1->flags = 0;
- digestsize = crypto_ahash_digestsize(state->sha1);
+ digestsize = crypto_shash_digestsize(shash);
if (digestsize < MPPE_MAX_KEY_LEN)
goto out_free;
@@ -246,7 +246,11 @@ static void *mppe_alloc(unsigned char *options, int optlen)
out_free:
kfree(state->sha1_digest);
- crypto_free_ahash(state->sha1);
+ if (state->sha1) {
+ if (state->sha1->tfm)
+ crypto_free_shash(state->sha1->tfm);
+ kzfree(state->sha1);
+ }
crypto_free_skcipher(state->arc4);
kfree(state);
out:
@@ -261,7 +265,8 @@ static void mppe_free(void *arg)
struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
if (state) {
kfree(state->sha1_digest);
- crypto_free_ahash(state->sha1);
+ crypto_free_shash(state->sha1->tfm);
+ kzfree(state->sha1);
crypto_free_skcipher(state->arc4);
kfree(state);
}
--
2.17.1
--
Kees Cook
Pixel Security
^ permalink raw reply related [flat|nested] 10+ messages in thread* [PATCH] ppp: mppe: Remove VLA usage
@ 2018-07-16 4:05 ` Kees Cook
0 siblings, 0 replies; 10+ messages in thread
From: Kees Cook @ 2018-07-16 4:05 UTC (permalink / raw)
To: Paul Mackerras, David S. Miller
Cc: Herbert Xu, Arnd Bergmann, Eric Biggers, Gustavo A. R. Silva,
linux-ppp, netdev, linux-kernel
In the quest to remove all stack VLA usage from the kernel[1], this
removes the discouraged use of AHASH_REQUEST_ON_STACK (and associated
VLA) by switching to shash directly and keeping the associated descriptor
allocated with the regular state on the heap.
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/net/ppp/ppp_mppe.c | 57 +++++++++++++++++++++-----------------
1 file changed, 31 insertions(+), 26 deletions(-)
diff --git a/drivers/net/ppp/ppp_mppe.c b/drivers/net/ppp/ppp_mppe.c
index 6c7fd98cb00a..5b4b81027a75 100644
--- a/drivers/net/ppp/ppp_mppe.c
+++ b/drivers/net/ppp/ppp_mppe.c
@@ -96,7 +96,7 @@ static inline void sha_pad_init(struct sha_pad *shapad)
*/
struct ppp_mppe_state {
struct crypto_skcipher *arc4;
- struct crypto_ahash *sha1;
+ struct shash_desc *sha1;
unsigned char *sha1_digest;
unsigned char master_key[MPPE_MAX_KEY_LEN];
unsigned char session_key[MPPE_MAX_KEY_LEN];
@@ -136,25 +136,16 @@ struct ppp_mppe_state {
*/
static void get_new_key_from_sha(struct ppp_mppe_state * state)
{
- AHASH_REQUEST_ON_STACK(req, state->sha1);
- struct scatterlist sg[4];
- unsigned int nbytes;
-
- sg_init_table(sg, 4);
-
- nbytes = setup_sg(&sg[0], state->master_key, state->keylen);
- nbytes += setup_sg(&sg[1], sha_pad->sha_pad1,
- sizeof(sha_pad->sha_pad1));
- nbytes += setup_sg(&sg[2], state->session_key, state->keylen);
- nbytes += setup_sg(&sg[3], sha_pad->sha_pad2,
- sizeof(sha_pad->sha_pad2));
-
- ahash_request_set_tfm(req, state->sha1);
- ahash_request_set_callback(req, 0, NULL, NULL);
- ahash_request_set_crypt(req, sg, state->sha1_digest, nbytes);
-
- crypto_ahash_digest(req);
- ahash_request_zero(req);
+ crypto_shash_init(state->sha1);
+ crypto_shash_update(state->sha1, state->master_key,
+ state->keylen);
+ crypto_shash_update(state->sha1, sha_pad->sha_pad1,
+ sizeof(sha_pad->sha_pad1));
+ crypto_shash_update(state->sha1, state->session_key,
+ state->keylen);
+ crypto_shash_update(state->sha1, sha_pad->sha_pad2,
+ sizeof(sha_pad->sha_pad2));
+ crypto_shash_final(state->sha1, state->sha1_digest);
}
/*
@@ -200,6 +191,7 @@ static void mppe_rekey(struct ppp_mppe_state * state, int initial_key)
static void *mppe_alloc(unsigned char *options, int optlen)
{
struct ppp_mppe_state *state;
+ struct crypto_shash *shash;
unsigned int digestsize;
if (optlen != CILEN_MPPE + sizeof(state->master_key) ||
@@ -217,13 +209,21 @@ static void *mppe_alloc(unsigned char *options, int optlen)
goto out_free;
}
- state->sha1 = crypto_alloc_ahash("sha1", 0, CRYPTO_ALG_ASYNC);
- if (IS_ERR(state->sha1)) {
- state->sha1 = NULL;
+ shash = crypto_alloc_shash("sha1", 0, 0);
+ if (IS_ERR(shash))
+ goto out_free;
+
+ state->sha1 = kmalloc(sizeof(*state->sha1) +
+ crypto_shash_descsize(shash),
+ GFP_KERNEL);
+ if (!state->sha1) {
+ crypto_free_shash(shash);
goto out_free;
}
+ state->sha1->tfm = shash;
+ state->sha1->flags = 0;
- digestsize = crypto_ahash_digestsize(state->sha1);
+ digestsize = crypto_shash_digestsize(shash);
if (digestsize < MPPE_MAX_KEY_LEN)
goto out_free;
@@ -246,7 +246,11 @@ static void *mppe_alloc(unsigned char *options, int optlen)
out_free:
kfree(state->sha1_digest);
- crypto_free_ahash(state->sha1);
+ if (state->sha1) {
+ if (state->sha1->tfm)
+ crypto_free_shash(state->sha1->tfm);
+ kzfree(state->sha1);
+ }
crypto_free_skcipher(state->arc4);
kfree(state);
out:
@@ -261,7 +265,8 @@ static void mppe_free(void *arg)
struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
if (state) {
kfree(state->sha1_digest);
- crypto_free_ahash(state->sha1);
+ crypto_free_shash(state->sha1->tfm);
+ kzfree(state->sha1);
crypto_free_skcipher(state->arc4);
kfree(state);
}
--
2.17.1
--
Kees Cook
Pixel Security
^ permalink raw reply related [flat|nested] 10+ messages in thread* Re: [PATCH] ppp: mppe: Remove VLA usage
2018-07-16 4:05 ` Kees Cook
@ 2018-07-16 11:01 ` Arnd Bergmann
-1 siblings, 0 replies; 10+ messages in thread
From: Arnd Bergmann @ 2018-07-16 11:01 UTC (permalink / raw)
To: Kees Cook
Cc: Paul Mackerras, David S. Miller, Herbert Xu, Eric Biggers,
Gustavo A. R. Silva, linux-ppp, Networking,
Linux Kernel Mailing List
On Mon, Jul 16, 2018 at 6:05 AM, Kees Cook <keescook@chromium.org> wrote:
> In the quest to remove all stack VLA usage from the kernel[1], this
> removes the discouraged use of AHASH_REQUEST_ON_STACK (and associated
> VLA) by switching to shash directly and keeping the associated descriptor
> allocated with the regular state on the heap.
>
> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
I had concerns at first that this approach might make it slower, but
upon reading through implementation of the shash_ahash_ implementation,
I concluded that it can only be better than before, improving both
performance and stack usage.
Acked-by: Arnd Bergmann <arnd@arndb.de>
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] ppp: mppe: Remove VLA usage
@ 2018-07-16 11:01 ` Arnd Bergmann
0 siblings, 0 replies; 10+ messages in thread
From: Arnd Bergmann @ 2018-07-16 11:01 UTC (permalink / raw)
To: Kees Cook
Cc: Paul Mackerras, David S. Miller, Herbert Xu, Eric Biggers,
Gustavo A. R. Silva, linux-ppp, Networking,
Linux Kernel Mailing List
On Mon, Jul 16, 2018 at 6:05 AM, Kees Cook <keescook@chromium.org> wrote:
> In the quest to remove all stack VLA usage from the kernel[1], this
> removes the discouraged use of AHASH_REQUEST_ON_STACK (and associated
> VLA) by switching to shash directly and keeping the associated descriptor
> allocated with the regular state on the heap.
>
> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
I had concerns at first that this approach might make it slower, but
upon reading through implementation of the shash_ahash_ implementation,
I concluded that it can only be better than before, improving both
performance and stack usage.
Acked-by: Arnd Bergmann <arnd@arndb.de>
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] ppp: mppe: Remove VLA usage
2018-07-16 11:01 ` Arnd Bergmann
@ 2018-08-02 23:27 ` Kees Cook
-1 siblings, 0 replies; 10+ messages in thread
From: Kees Cook @ 2018-08-02 23:27 UTC (permalink / raw)
To: Paul Mackerras
Cc: Arnd Bergmann, David S. Miller, Herbert Xu, Eric Biggers,
Gustavo A. R. Silva, linux-ppp, Networking,
Linux Kernel Mailing List
On Mon, Jul 16, 2018 at 4:01 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Mon, Jul 16, 2018 at 6:05 AM, Kees Cook <keescook@chromium.org> wrote:
>> In the quest to remove all stack VLA usage from the kernel[1], this
>> removes the discouraged use of AHASH_REQUEST_ON_STACK (and associated
>> VLA) by switching to shash directly and keeping the associated descriptor
>> allocated with the regular state on the heap.
>>
>> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>>
>> Signed-off-by: Kees Cook <keescook@chromium.org>
>
> I had concerns at first that this approach might make it slower, but
> upon reading through implementation of the shash_ahash_ implementation,
> I concluded that it can only be better than before, improving both
> performance and stack usage.
>
> Acked-by: Arnd Bergmann <arnd@arndb.de>
Paul,
Is this something you can take via your tree?
Thanks,
-Kees
--
Kees Cook
Pixel Security
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] ppp: mppe: Remove VLA usage
@ 2018-08-02 23:27 ` Kees Cook
0 siblings, 0 replies; 10+ messages in thread
From: Kees Cook @ 2018-08-02 23:27 UTC (permalink / raw)
To: Paul Mackerras
Cc: Arnd Bergmann, David S. Miller, Herbert Xu, Eric Biggers,
Gustavo A. R. Silva, linux-ppp, Networking,
Linux Kernel Mailing List
On Mon, Jul 16, 2018 at 4:01 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Mon, Jul 16, 2018 at 6:05 AM, Kees Cook <keescook@chromium.org> wrote:
>> In the quest to remove all stack VLA usage from the kernel[1], this
>> removes the discouraged use of AHASH_REQUEST_ON_STACK (and associated
>> VLA) by switching to shash directly and keeping the associated descriptor
>> allocated with the regular state on the heap.
>>
>> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>>
>> Signed-off-by: Kees Cook <keescook@chromium.org>
>
> I had concerns at first that this approach might make it slower, but
> upon reading through implementation of the shash_ahash_ implementation,
> I concluded that it can only be better than before, improving both
> performance and stack usage.
>
> Acked-by: Arnd Bergmann <arnd@arndb.de>
Paul,
Is this something you can take via your tree?
Thanks,
-Kees
--
Kees Cook
Pixel Security
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] ppp: mppe: Remove VLA usage
2018-08-02 23:27 ` Kees Cook
@ 2018-08-03 3:13 ` Paul Mackerras
-1 siblings, 0 replies; 10+ messages in thread
From: Paul Mackerras @ 2018-08-03 3:13 UTC (permalink / raw)
To: Kees Cook
Cc: Arnd Bergmann, David S. Miller, Herbert Xu, Eric Biggers,
Gustavo A. R. Silva, linux-ppp, Networking,
Linux Kernel Mailing List
On Thu, Aug 02, 2018 at 04:27:01PM -0700, Kees Cook wrote:
> On Mon, Jul 16, 2018 at 4:01 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> > On Mon, Jul 16, 2018 at 6:05 AM, Kees Cook <keescook@chromium.org> wrote:
> >> In the quest to remove all stack VLA usage from the kernel[1], this
> >> removes the discouraged use of AHASH_REQUEST_ON_STACK (and associated
> >> VLA) by switching to shash directly and keeping the associated descriptor
> >> allocated with the regular state on the heap.
> >>
> >> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
> >>
> >> Signed-off-by: Kees Cook <keescook@chromium.org>
> >
> > I had concerns at first that this approach might make it slower, but
> > upon reading through implementation of the shash_ahash_ implementation,
> > I concluded that it can only be better than before, improving both
> > performance and stack usage.
> >
> > Acked-by: Arnd Bergmann <arnd@arndb.de>
>
> Paul,
>
> Is this something you can take via your tree?
No, it would go via the netdev tree, I expect.
Paul.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] ppp: mppe: Remove VLA usage
@ 2018-08-03 3:13 ` Paul Mackerras
0 siblings, 0 replies; 10+ messages in thread
From: Paul Mackerras @ 2018-08-03 3:13 UTC (permalink / raw)
To: Kees Cook
Cc: Arnd Bergmann, David S. Miller, Herbert Xu, Eric Biggers,
Gustavo A. R. Silva, linux-ppp, Networking,
Linux Kernel Mailing List
On Thu, Aug 02, 2018 at 04:27:01PM -0700, Kees Cook wrote:
> On Mon, Jul 16, 2018 at 4:01 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> > On Mon, Jul 16, 2018 at 6:05 AM, Kees Cook <keescook@chromium.org> wrote:
> >> In the quest to remove all stack VLA usage from the kernel[1], this
> >> removes the discouraged use of AHASH_REQUEST_ON_STACK (and associated
> >> VLA) by switching to shash directly and keeping the associated descriptor
> >> allocated with the regular state on the heap.
> >>
> >> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
> >>
> >> Signed-off-by: Kees Cook <keescook@chromium.org>
> >
> > I had concerns at first that this approach might make it slower, but
> > upon reading through implementation of the shash_ahash_ implementation,
> > I concluded that it can only be better than before, improving both
> > performance and stack usage.
> >
> > Acked-by: Arnd Bergmann <arnd@arndb.de>
>
> Paul,
>
> Is this something you can take via your tree?
No, it would go via the netdev tree, I expect.
Paul.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] ppp: mppe: Remove VLA usage
2018-07-16 4:05 ` Kees Cook
@ 2018-07-16 17:36 ` Eric Biggers
-1 siblings, 0 replies; 10+ messages in thread
From: Eric Biggers @ 2018-07-16 17:36 UTC (permalink / raw)
To: Kees Cook
Cc: Paul Mackerras, David S. Miller, Herbert Xu, Arnd Bergmann,
Gustavo A. R. Silva, linux-ppp, netdev, linux-kernel
On Sun, Jul 15, 2018 at 09:05:16PM -0700, Kees Cook wrote:
> In the quest to remove all stack VLA usage from the kernel[1], this
> removes the discouraged use of AHASH_REQUEST_ON_STACK (and associated
> VLA) by switching to shash directly and keeping the associated descriptor
> allocated with the regular state on the heap.
>
> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> drivers/net/ppp/ppp_mppe.c | 57 +++++++++++++++++++++-----------------
> 1 file changed, 31 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/net/ppp/ppp_mppe.c b/drivers/net/ppp/ppp_mppe.c
> index 6c7fd98cb00a..5b4b81027a75 100644
> --- a/drivers/net/ppp/ppp_mppe.c
> +++ b/drivers/net/ppp/ppp_mppe.c
> @@ -96,7 +96,7 @@ static inline void sha_pad_init(struct sha_pad *shapad)
> */
> struct ppp_mppe_state {
> struct crypto_skcipher *arc4;
> - struct crypto_ahash *sha1;
> + struct shash_desc *sha1;
> unsigned char *sha1_digest;
> unsigned char master_key[MPPE_MAX_KEY_LEN];
> unsigned char session_key[MPPE_MAX_KEY_LEN];
> @@ -136,25 +136,16 @@ struct ppp_mppe_state {
> */
> static void get_new_key_from_sha(struct ppp_mppe_state * state)
> {
> - AHASH_REQUEST_ON_STACK(req, state->sha1);
> - struct scatterlist sg[4];
> - unsigned int nbytes;
> -
> - sg_init_table(sg, 4);
> -
> - nbytes = setup_sg(&sg[0], state->master_key, state->keylen);
> - nbytes += setup_sg(&sg[1], sha_pad->sha_pad1,
> - sizeof(sha_pad->sha_pad1));
> - nbytes += setup_sg(&sg[2], state->session_key, state->keylen);
> - nbytes += setup_sg(&sg[3], sha_pad->sha_pad2,
> - sizeof(sha_pad->sha_pad2));
> -
> - ahash_request_set_tfm(req, state->sha1);
> - ahash_request_set_callback(req, 0, NULL, NULL);
> - ahash_request_set_crypt(req, sg, state->sha1_digest, nbytes);
> -
> - crypto_ahash_digest(req);
> - ahash_request_zero(req);
> + crypto_shash_init(state->sha1);
> + crypto_shash_update(state->sha1, state->master_key,
> + state->keylen);
> + crypto_shash_update(state->sha1, sha_pad->sha_pad1,
> + sizeof(sha_pad->sha_pad1));
> + crypto_shash_update(state->sha1, state->session_key,
> + state->keylen);
> + crypto_shash_update(state->sha1, sha_pad->sha_pad2,
> + sizeof(sha_pad->sha_pad2));
> + crypto_shash_final(state->sha1, state->sha1_digest);
> }
>
> /*
> @@ -200,6 +191,7 @@ static void mppe_rekey(struct ppp_mppe_state * state, int initial_key)
> static void *mppe_alloc(unsigned char *options, int optlen)
> {
> struct ppp_mppe_state *state;
> + struct crypto_shash *shash;
> unsigned int digestsize;
>
> if (optlen != CILEN_MPPE + sizeof(state->master_key) ||
> @@ -217,13 +209,21 @@ static void *mppe_alloc(unsigned char *options, int optlen)
> goto out_free;
> }
>
> - state->sha1 = crypto_alloc_ahash("sha1", 0, CRYPTO_ALG_ASYNC);
> - if (IS_ERR(state->sha1)) {
> - state->sha1 = NULL;
> + shash = crypto_alloc_shash("sha1", 0, 0);
> + if (IS_ERR(shash))
> + goto out_free;
> +
> + state->sha1 = kmalloc(sizeof(*state->sha1) +
> + crypto_shash_descsize(shash),
> + GFP_KERNEL);
> + if (!state->sha1) {
> + crypto_free_shash(shash);
> goto out_free;
> }
> + state->sha1->tfm = shash;
> + state->sha1->flags = 0;
>
> - digestsize = crypto_ahash_digestsize(state->sha1);
> + digestsize = crypto_shash_digestsize(shash);
> if (digestsize < MPPE_MAX_KEY_LEN)
> goto out_free;
>
> @@ -246,7 +246,11 @@ static void *mppe_alloc(unsigned char *options, int optlen)
>
> out_free:
> kfree(state->sha1_digest);
> - crypto_free_ahash(state->sha1);
> + if (state->sha1) {
> + if (state->sha1->tfm)
> + crypto_free_shash(state->sha1->tfm);
It's not necessary to check for NULL before calling crypto_free_shash().
Otherwise this looks good, though I dislike how the error codes aren't checked
in get_new_key_from_sha() (of course, they weren't before this patch either).
> + kzfree(state->sha1);
> + }
> crypto_free_skcipher(state->arc4);
> kfree(state);
> out:
> @@ -261,7 +265,8 @@ static void mppe_free(void *arg)
> struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
> if (state) {
> kfree(state->sha1_digest);
> - crypto_free_ahash(state->sha1);
> + crypto_free_shash(state->sha1->tfm);
> + kzfree(state->sha1);
> crypto_free_skcipher(state->arc4);
> kfree(state);
> }
> --
> 2.17.1
>
>
> --
> Kees Cook
> Pixel Security
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH] ppp: mppe: Remove VLA usage
@ 2018-07-16 17:36 ` Eric Biggers
0 siblings, 0 replies; 10+ messages in thread
From: Eric Biggers @ 2018-07-16 17:36 UTC (permalink / raw)
To: Kees Cook
Cc: Paul Mackerras, David S. Miller, Herbert Xu, Arnd Bergmann,
Gustavo A. R. Silva, linux-ppp, netdev, linux-kernel
On Sun, Jul 15, 2018 at 09:05:16PM -0700, Kees Cook wrote:
> In the quest to remove all stack VLA usage from the kernel[1], this
> removes the discouraged use of AHASH_REQUEST_ON_STACK (and associated
> VLA) by switching to shash directly and keeping the associated descriptor
> allocated with the regular state on the heap.
>
> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> drivers/net/ppp/ppp_mppe.c | 57 +++++++++++++++++++++-----------------
> 1 file changed, 31 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/net/ppp/ppp_mppe.c b/drivers/net/ppp/ppp_mppe.c
> index 6c7fd98cb00a..5b4b81027a75 100644
> --- a/drivers/net/ppp/ppp_mppe.c
> +++ b/drivers/net/ppp/ppp_mppe.c
> @@ -96,7 +96,7 @@ static inline void sha_pad_init(struct sha_pad *shapad)
> */
> struct ppp_mppe_state {
> struct crypto_skcipher *arc4;
> - struct crypto_ahash *sha1;
> + struct shash_desc *sha1;
> unsigned char *sha1_digest;
> unsigned char master_key[MPPE_MAX_KEY_LEN];
> unsigned char session_key[MPPE_MAX_KEY_LEN];
> @@ -136,25 +136,16 @@ struct ppp_mppe_state {
> */
> static void get_new_key_from_sha(struct ppp_mppe_state * state)
> {
> - AHASH_REQUEST_ON_STACK(req, state->sha1);
> - struct scatterlist sg[4];
> - unsigned int nbytes;
> -
> - sg_init_table(sg, 4);
> -
> - nbytes = setup_sg(&sg[0], state->master_key, state->keylen);
> - nbytes += setup_sg(&sg[1], sha_pad->sha_pad1,
> - sizeof(sha_pad->sha_pad1));
> - nbytes += setup_sg(&sg[2], state->session_key, state->keylen);
> - nbytes += setup_sg(&sg[3], sha_pad->sha_pad2,
> - sizeof(sha_pad->sha_pad2));
> -
> - ahash_request_set_tfm(req, state->sha1);
> - ahash_request_set_callback(req, 0, NULL, NULL);
> - ahash_request_set_crypt(req, sg, state->sha1_digest, nbytes);
> -
> - crypto_ahash_digest(req);
> - ahash_request_zero(req);
> + crypto_shash_init(state->sha1);
> + crypto_shash_update(state->sha1, state->master_key,
> + state->keylen);
> + crypto_shash_update(state->sha1, sha_pad->sha_pad1,
> + sizeof(sha_pad->sha_pad1));
> + crypto_shash_update(state->sha1, state->session_key,
> + state->keylen);
> + crypto_shash_update(state->sha1, sha_pad->sha_pad2,
> + sizeof(sha_pad->sha_pad2));
> + crypto_shash_final(state->sha1, state->sha1_digest);
> }
>
> /*
> @@ -200,6 +191,7 @@ static void mppe_rekey(struct ppp_mppe_state * state, int initial_key)
> static void *mppe_alloc(unsigned char *options, int optlen)
> {
> struct ppp_mppe_state *state;
> + struct crypto_shash *shash;
> unsigned int digestsize;
>
> if (optlen != CILEN_MPPE + sizeof(state->master_key) ||
> @@ -217,13 +209,21 @@ static void *mppe_alloc(unsigned char *options, int optlen)
> goto out_free;
> }
>
> - state->sha1 = crypto_alloc_ahash("sha1", 0, CRYPTO_ALG_ASYNC);
> - if (IS_ERR(state->sha1)) {
> - state->sha1 = NULL;
> + shash = crypto_alloc_shash("sha1", 0, 0);
> + if (IS_ERR(shash))
> + goto out_free;
> +
> + state->sha1 = kmalloc(sizeof(*state->sha1) +
> + crypto_shash_descsize(shash),
> + GFP_KERNEL);
> + if (!state->sha1) {
> + crypto_free_shash(shash);
> goto out_free;
> }
> + state->sha1->tfm = shash;
> + state->sha1->flags = 0;
>
> - digestsize = crypto_ahash_digestsize(state->sha1);
> + digestsize = crypto_shash_digestsize(shash);
> if (digestsize < MPPE_MAX_KEY_LEN)
> goto out_free;
>
> @@ -246,7 +246,11 @@ static void *mppe_alloc(unsigned char *options, int optlen)
>
> out_free:
> kfree(state->sha1_digest);
> - crypto_free_ahash(state->sha1);
> + if (state->sha1) {
> + if (state->sha1->tfm)
> + crypto_free_shash(state->sha1->tfm);
It's not necessary to check for NULL before calling crypto_free_shash().
Otherwise this looks good, though I dislike how the error codes aren't checked
in get_new_key_from_sha() (of course, they weren't before this patch either).
> + kzfree(state->sha1);
> + }
> crypto_free_skcipher(state->arc4);
> kfree(state);
> out:
> @@ -261,7 +265,8 @@ static void mppe_free(void *arg)
> struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
> if (state) {
> kfree(state->sha1_digest);
> - crypto_free_ahash(state->sha1);
> + crypto_free_shash(state->sha1->tfm);
> + kzfree(state->sha1);
> crypto_free_skcipher(state->arc4);
> kfree(state);
> }
> --
> 2.17.1
>
>
> --
> Kees Cook
> Pixel Security
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2018-08-03 3:13 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-07-16 4:05 [PATCH] ppp: mppe: Remove VLA usage Kees Cook
2018-07-16 4:05 ` Kees Cook
2018-07-16 11:01 ` Arnd Bergmann
2018-07-16 11:01 ` Arnd Bergmann
2018-08-02 23:27 ` Kees Cook
2018-08-02 23:27 ` Kees Cook
2018-08-03 3:13 ` Paul Mackerras
2018-08-03 3:13 ` Paul Mackerras
2018-07-16 17:36 ` Eric Biggers
2018-07-16 17:36 ` Eric Biggers
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.