The value stored in last_data must be primed for FIPS 140-2 purposes. Upon
first use, either on system startup or after an RNDCLEARPOOL ioctl, we
need to take an initial random sample, store it internally in last_data,
then pass along the value after that to the requester, so that consistency
checks aren't being run against stale and possibly known data.
CC: Herbert Xu <[email protected]>
CC: "David S. Miller" <[email protected]>
CC: Neil Horman <[email protected]>
CC: Matt Mackall <[email protected]>
CC: [email protected]
Signed-off-by: Jarod Wilson <[email protected]>
---
drivers/char/random.c | 11 +++++++++++
1 files changed, 11 insertions(+), 0 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index b86eae9..24d17b8 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -437,6 +437,7 @@ struct entropy_store {
int entropy_count;
int entropy_total;
unsigned int initialized:1;
+ bool last_data_init;
__u8 last_data[EXTRACT_SIZE];
};
@@ -967,6 +968,15 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
if (fips_enabled) {
unsigned long flags;
+ /* prime last_data value if need be, per fips 140-2 */
+ if (!r->last_data_init) {
+ spin_lock_irqsave(&r->lock, flags);
+ memcpy(r->last_data, tmp, EXTRACT_SIZE);
+ r->last_data_init = true;
+ spin_unlock_irqrestore(&r->lock, flags);
+ continue;
+ }
+
spin_lock_irqsave(&r->lock, flags);
if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
panic("Hardware RNG duplicated output!\n");
@@ -1086,6 +1096,7 @@ static void init_std_data(struct entropy_store *r)
r->entropy_count = 0;
r->entropy_total = 0;
+ r->last_data_init = false;
mix_pool_bytes(r, &now, sizeof(now), NULL);
for (i = r->poolinfo->POOLBYTES; i > 0; i -= sizeof(rv)) {
if (!arch_get_random_long(&rv))
--
1.7.1
On Mon, Nov 05, 2012 at 04:00:10PM -0500, Jarod Wilson wrote:
> The value stored in last_data must be primed for FIPS 140-2 purposes. Upon
> first use, either on system startup or after an RNDCLEARPOOL ioctl, we
> need to take an initial random sample, store it internally in last_data,
> then pass along the value after that to the requester, so that consistency
> checks aren't being run against stale and possibly known data.
>
> CC: Herbert Xu <[email protected]>
> CC: "David S. Miller" <[email protected]>
> CC: Neil Horman <[email protected]>
> CC: Matt Mackall <[email protected]>
> CC: [email protected]
> Signed-off-by: Jarod Wilson <[email protected]>
> ---
> drivers/char/random.c | 11 +++++++++++
> 1 files changed, 11 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/char/random.c b/drivers/char/random.c
> index b86eae9..24d17b8 100644
> --- a/drivers/char/random.c
> +++ b/drivers/char/random.c
> @@ -437,6 +437,7 @@ struct entropy_store {
> int entropy_count;
> int entropy_total;
> unsigned int initialized:1;
> + bool last_data_init;
> __u8 last_data[EXTRACT_SIZE];
> };
>
> @@ -967,6 +968,15 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
> if (fips_enabled) {
> unsigned long flags;
>
> + /* prime last_data value if need be, per fips 140-2 */
> + if (!r->last_data_init) {
> + spin_lock_irqsave(&r->lock, flags);
> + memcpy(r->last_data, tmp, EXTRACT_SIZE);
> + r->last_data_init = true;
> + spin_unlock_irqrestore(&r->lock, flags);
> + continue;
Continue? Is that left over from earlier work? Or did you have some other
purpose in mind for it?
Also, not that its in a hot path or anything, but it might be nice to
consolodate this code such that you only lock and unlock r->flags once instead
of twice here.
Best
Neil
> + }
> +
> spin_lock_irqsave(&r->lock, flags);
> if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
> panic("Hardware RNG duplicated output!\n");
> @@ -1086,6 +1096,7 @@ static void init_std_data(struct entropy_store *r)
>
> r->entropy_count = 0;
> r->entropy_total = 0;
> + r->last_data_init = false;
> mix_pool_bytes(r, &now, sizeof(now), NULL);
> for (i = r->poolinfo->POOLBYTES; i > 0; i -= sizeof(rv)) {
> if (!arch_get_random_long(&rv))
> --
> 1.7.1
>
>
On Tue, Nov 06, 2012 at 07:05:23AM -0500, Neil Horman wrote:
> On Mon, Nov 05, 2012 at 04:00:10PM -0500, Jarod Wilson wrote:
> > The value stored in last_data must be primed for FIPS 140-2 purposes. Upon
> > first use, either on system startup or after an RNDCLEARPOOL ioctl, we
> > need to take an initial random sample, store it internally in last_data,
> > then pass along the value after that to the requester, so that consistency
> > checks aren't being run against stale and possibly known data.
> >
> > CC: Herbert Xu <[email protected]>
> > CC: "David S. Miller" <[email protected]>
> > CC: Neil Horman <[email protected]>
> > CC: Matt Mackall <[email protected]>
> > CC: [email protected]
> > Signed-off-by: Jarod Wilson <[email protected]>
> > ---
> > drivers/char/random.c | 11 +++++++++++
> > 1 files changed, 11 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/char/random.c b/drivers/char/random.c
> > index b86eae9..24d17b8 100644
> > --- a/drivers/char/random.c
> > +++ b/drivers/char/random.c
> > @@ -437,6 +437,7 @@ struct entropy_store {
> > int entropy_count;
> > int entropy_total;
> > unsigned int initialized:1;
> > + bool last_data_init;
> > __u8 last_data[EXTRACT_SIZE];
> > };
> >
> > @@ -967,6 +968,15 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
> > if (fips_enabled) {
> > unsigned long flags;
> >
> > + /* prime last_data value if need be, per fips 140-2 */
> > + if (!r->last_data_init) {
> > + spin_lock_irqsave(&r->lock, flags);
> > + memcpy(r->last_data, tmp, EXTRACT_SIZE);
> > + r->last_data_init = true;
> > + spin_unlock_irqrestore(&r->lock, flags);
> > + continue;
> Continue? Is that left over from earlier work? Or did you have some other
> purpose in mind for it?
The continue takes you back to the top of the while loop for another
extract_buf() call, but continue could simply be replaced with another
extract_buf() call, so we don't have to restart the loop and check
last_data_init again. Otherwise, we're going to fail the memcmp and panic,
because tmp and r->last_data will be identical.
> Also, not that its in a hot path or anything, but it might be nice to
> consolodate this code such that you only lock and unlock r->flags once instead
> of twice here.
I thought about that, but figured it would be more trouble and possibly
more code to execute than it was worth in the normal case. But I can spin
up a v2 that tries to be a bit cleaner here.
--
Jarod Wilson
[email protected]
The value stored in last_data must be primed for FIPS 140-2 purposes. Upon
first use, either on system startup or after an RNDCLEARPOOL ioctl, we
need to take an initial random sample, store it internally in last_data,
then pass along the value after that to the requester, so that consistency
checks aren't being run against stale and possibly known data.
v2: streamline code flow a bit, eliminating extra loop and spinlock in the
case where we need to prime, and account for the extra primer bits.
CC: Herbert Xu <[email protected]>
CC: "David S. Miller" <[email protected]>
CC: Neil Horman <[email protected]>
CC: Matt Mackall <[email protected]>
CC: [email protected]
Signed-off-by: Jarod Wilson <[email protected]>
---
drivers/char/random.c | 15 +++++++++++++++
1 files changed, 15 insertions(+), 0 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index b86eae9..6bdd57f 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -437,6 +437,7 @@ struct entropy_store {
int entropy_count;
int entropy_total;
unsigned int initialized:1;
+ bool last_data_init;
__u8 last_data[EXTRACT_SIZE];
};
@@ -957,6 +958,10 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
ssize_t ret = 0, i;
__u8 tmp[EXTRACT_SIZE];
+ /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
+ if (fips_enabled && !r->last_data_init)
+ nbytes += EXTRACT_SIZE;
+
trace_extract_entropy(r->name, nbytes, r->entropy_count, _RET_IP_);
xfer_secondary_pool(r, nbytes);
nbytes = account(r, nbytes, min, reserved);
@@ -968,6 +973,15 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
unsigned long flags;
spin_lock_irqsave(&r->lock, flags);
+
+ /* prime last_data value if need be, per fips 140-2 */
+ if (!r->last_data_init) {
+ memcpy(r->last_data, tmp, EXTRACT_SIZE);
+ r->last_data_init = true;
+ nbytes -= EXTRACT_SIZE;
+ extract_buf(r, tmp);
+ }
+
if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
panic("Hardware RNG duplicated output!\n");
memcpy(r->last_data, tmp, EXTRACT_SIZE);
@@ -1086,6 +1100,7 @@ static void init_std_data(struct entropy_store *r)
r->entropy_count = 0;
r->entropy_total = 0;
+ r->last_data_init = false;
mix_pool_bytes(r, &now, sizeof(now), NULL);
for (i = r->poolinfo->POOLBYTES; i > 0; i -= sizeof(rv)) {
if (!arch_get_random_long(&rv))
--
1.7.1
The value stored in last_data must be primed for FIPS 140-2 purposes. Upon
first use, either on system startup or after an RNDCLEARPOOL ioctl, we
need to take an initial random sample, store it internally in last_data,
then pass along the value after that to the requester, so that consistency
checks aren't being run against stale and possibly known data.
v2: streamline code flow a bit, eliminating extra loop and spinlock in the
case where we need to prime, and account for the extra primer bits.
v3: extract_buf() can't be called with spinlock already held, so bring
back some extra lock/unlock calls.
CC: Herbert Xu <[email protected]>
CC: "David S. Miller" <[email protected]>
CC: Neil Horman <[email protected]>
CC: Matt Mackall <[email protected]>
CC: [email protected]
Signed-off-by: Jarod Wilson <[email protected]>
---
drivers/char/random.c | 17 +++++++++++++++++
1 files changed, 17 insertions(+), 0 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index b86eae9..d0139df 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -437,6 +437,7 @@ struct entropy_store {
int entropy_count;
int entropy_total;
unsigned int initialized:1;
+ bool last_data_init;
__u8 last_data[EXTRACT_SIZE];
};
@@ -957,6 +958,10 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
ssize_t ret = 0, i;
__u8 tmp[EXTRACT_SIZE];
+ /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
+ if (fips_enabled && !r->last_data_init)
+ nbytes += EXTRACT_SIZE;
+
trace_extract_entropy(r->name, nbytes, r->entropy_count, _RET_IP_);
xfer_secondary_pool(r, nbytes);
nbytes = account(r, nbytes, min, reserved);
@@ -967,6 +972,17 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
if (fips_enabled) {
unsigned long flags;
+
+ /* prime last_data value if need be, per fips 140-2 */
+ if (!r->last_data_init) {
+ spin_lock_irqsave(&r->lock, flags);
+ memcpy(r->last_data, tmp, EXTRACT_SIZE);
+ r->last_data_init = true;
+ nbytes -= EXTRACT_SIZE;
+ spin_unlock_irqrestore(&r->lock, flags);
+ extract_buf(r, tmp);
+ }
+
spin_lock_irqsave(&r->lock, flags);
if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
panic("Hardware RNG duplicated output!\n");
@@ -1086,6 +1102,7 @@ static void init_std_data(struct entropy_store *r)
r->entropy_count = 0;
r->entropy_total = 0;
+ r->last_data_init = false;
mix_pool_bytes(r, &now, sizeof(now), NULL);
for (i = r->poolinfo->POOLBYTES; i > 0; i -= sizeof(rv)) {
if (!arch_get_random_long(&rv))
--
1.7.1
On Tue, Nov 06, 2012 at 10:42:42AM -0500, Jarod Wilson wrote:
> The value stored in last_data must be primed for FIPS 140-2 purposes. Upon
> first use, either on system startup or after an RNDCLEARPOOL ioctl, we
> need to take an initial random sample, store it internally in last_data,
> then pass along the value after that to the requester, so that consistency
> checks aren't being run against stale and possibly known data.
>
> v2: streamline code flow a bit, eliminating extra loop and spinlock in the
> case where we need to prime, and account for the extra primer bits.
>
> v3: extract_buf() can't be called with spinlock already held, so bring
> back some extra lock/unlock calls.
>
> CC: Herbert Xu <[email protected]>
> CC: "David S. Miller" <[email protected]>
> CC: Neil Horman <[email protected]>
> CC: Matt Mackall <[email protected]>
> CC: [email protected]
> Signed-off-by: Jarod Wilson <[email protected]>
> ---
> drivers/char/random.c | 17 +++++++++++++++++
> 1 files changed, 17 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/char/random.c b/drivers/char/random.c
> index b86eae9..d0139df 100644
> --- a/drivers/char/random.c
> +++ b/drivers/char/random.c
> @@ -437,6 +437,7 @@ struct entropy_store {
> int entropy_count;
> int entropy_total;
> unsigned int initialized:1;
> + bool last_data_init;
> __u8 last_data[EXTRACT_SIZE];
> };
>
> @@ -957,6 +958,10 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
> ssize_t ret = 0, i;
> __u8 tmp[EXTRACT_SIZE];
>
> + /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
> + if (fips_enabled && !r->last_data_init)
> + nbytes += EXTRACT_SIZE;
> +
> trace_extract_entropy(r->name, nbytes, r->entropy_count, _RET_IP_);
> xfer_secondary_pool(r, nbytes);
> nbytes = account(r, nbytes, min, reserved);
> @@ -967,6 +972,17 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
> if (fips_enabled) {
> unsigned long flags;
>
> +
> + /* prime last_data value if need be, per fips 140-2 */
> + if (!r->last_data_init) {
> + spin_lock_irqsave(&r->lock, flags);
> + memcpy(r->last_data, tmp, EXTRACT_SIZE);
> + r->last_data_init = true;
> + nbytes -= EXTRACT_SIZE;
> + spin_unlock_irqrestore(&r->lock, flags);
> + extract_buf(r, tmp);
> + }
> +
> spin_lock_irqsave(&r->lock, flags);
> if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
> panic("Hardware RNG duplicated output!\n");
> @@ -1086,6 +1102,7 @@ static void init_std_data(struct entropy_store *r)
>
> r->entropy_count = 0;
> r->entropy_total = 0;
> + r->last_data_init = false;
> mix_pool_bytes(r, &now, sizeof(now), NULL);
> for (i = r->poolinfo->POOLBYTES; i > 0; i -= sizeof(rv)) {
> if (!arch_get_random_long(&rv))
> --
> 1.7.1
>
>
Thanks Jarod.
Acked-by: Neil Horman <[email protected]>
On Tue, Nov 06, 2012 at 10:42:42AM -0500, Jarod Wilson wrote:
> The value stored in last_data must be primed for FIPS 140-2 purposes. Upon
> first use, either on system startup or after an RNDCLEARPOOL ioctl, we
> need to take an initial random sample, store it internally in last_data,
> then pass along the value after that to the requester, so that consistency
> checks aren't being run against stale and possibly known data.
>
> v2: streamline code flow a bit, eliminating extra loop and spinlock in the
> case where we need to prime, and account for the extra primer bits.
>
> v3: extract_buf() can't be called with spinlock already held, so bring
> back some extra lock/unlock calls.
>
> CC: Herbert Xu <[email protected]>
> CC: "David S. Miller" <[email protected]>
> CC: Neil Horman <[email protected]>
> CC: Matt Mackall <[email protected]>
> CC: [email protected]
> Signed-off-by: Jarod Wilson <[email protected]>
Thanks, applied to the /dev/random git tree.
- Ted