[patch 2/2] zcrypt: add support for large random numbers

From: Martin Schwidefsky
Date: Fri Mar 14 2008 - 05:31:43 EST

From: Ralph Wuerthner <rwuerthn@xxxxxxxxxx>

This patch allows user space applications to access large amounts of
truly random data. The random data source is the build-in hardware
random number generator on the CEX2C cards.

Signed-off-by: Ralph Wuerthner <rwuerthn@xxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
---

drivers/crypto/Kconfig | 1
drivers/s390/crypto/zcrypt_api.c | 120 +++++++++++++++++++++
drivers/s390/crypto/zcrypt_api.h | 8 +
drivers/s390/crypto/zcrypt_pcixcc.c | 199 +++++++++++++++++++++++++++++++++++-
4 files changed, 327 insertions(+), 1 deletion(-)

Index: quilt-2.6/drivers/crypto/Kconfig
===================================================================
--- quilt-2.6.orig/drivers/crypto/Kconfig
+++ quilt-2.6/drivers/crypto/Kconfig
@@ -64,6 +64,7 @@ config ZCRYPT
tristate "Support for PCI-attached cryptographic adapters"
depends on S390
select ZCRYPT_MONOLITHIC if ZCRYPT="y"
+ select HW_RANDOM
help
Select this option if you want to use a PCI-attached cryptographic
adapter like:
Index: quilt-2.6/drivers/s390/crypto/zcrypt_api.c
===================================================================
--- quilt-2.6.orig/drivers/s390/crypto/zcrypt_api.c
+++ quilt-2.6/drivers/s390/crypto/zcrypt_api.c
@@ -36,6 +36,7 @@
#include <linux/compat.h>
#include <asm/atomic.h>
#include <asm/uaccess.h>
+#include <linux/hw_random.h>

#include "zcrypt_api.h"

@@ -52,6 +53,9 @@ static LIST_HEAD(zcrypt_device_list);
static int zcrypt_device_count = 0;
static atomic_t zcrypt_open_count = ATOMIC_INIT(0);

+static int zcrypt_rng_device_add(void);
+static void zcrypt_rng_device_remove(void);
+
/**
* Device attributes common for all crypto devices.
*/
@@ -216,6 +220,22 @@ int zcrypt_device_register(struct zcrypt
__zcrypt_increase_preference(zdev);
zcrypt_device_count++;
spin_unlock_bh(&zcrypt_device_lock);
+ if (zdev->ops->rng) {
+ rc = zcrypt_rng_device_add();
+ if (rc)
+ goto out_unregister;
+ }
+ return 0;
+
+out_unregister:
+ spin_lock_bh(&zcrypt_device_lock);
+ zcrypt_device_count--;
+ list_del_init(&zdev->list);
+ spin_unlock_bh(&zcrypt_device_lock);
+ sysfs_remove_group(&zdev->ap_dev->device.kobj,
+ &zcrypt_device_attr_group);
+ put_device(&zdev->ap_dev->device);
+ zcrypt_device_put(zdev);
out:
return rc;
}
@@ -226,6 +246,8 @@ EXPORT_SYMBOL(zcrypt_device_register);
*/
void zcrypt_device_unregister(struct zcrypt_device *zdev)
{
+ if (zdev->ops->rng)
+ zcrypt_rng_device_remove();
spin_lock_bh(&zcrypt_device_lock);
zcrypt_device_count--;
list_del_init(&zdev->list);
@@ -427,6 +449,37 @@ static long zcrypt_send_cprb(struct ica_
return -ENODEV;
}

+static long zcrypt_rng(char *buffer)
+{
+ struct zcrypt_device *zdev;
+ int rc;
+
+ spin_lock_bh(&zcrypt_device_lock);
+ list_for_each_entry(zdev, &zcrypt_device_list, list) {
+ if (!zdev->online || !zdev->ops->rng)
+ continue;
+ zcrypt_device_get(zdev);
+ get_device(&zdev->ap_dev->device);
+ zdev->request_count++;
+ __zcrypt_decrease_preference(zdev);
+ if (try_module_get(zdev->ap_dev->drv->driver.owner)) {
+ spin_unlock_bh(&zcrypt_device_lock);
+ rc = zdev->ops->rng(zdev, buffer);
+ spin_lock_bh(&zcrypt_device_lock);
+ module_put(zdev->ap_dev->drv->driver.owner);
+ } else
+ rc = -EAGAIN;
+ zdev->request_count--;
+ __zcrypt_increase_preference(zdev);
+ put_device(&zdev->ap_dev->device);
+ zcrypt_device_put(zdev);
+ spin_unlock_bh(&zcrypt_device_lock);
+ return rc;
+ }
+ spin_unlock_bh(&zcrypt_device_lock);
+ return -ENODEV;
+}
+
static void zcrypt_status_mask(char status[AP_DEVICES])
{
struct zcrypt_device *zdev;
@@ -1041,6 +1094,73 @@ out:
return count;
}

+static int zcrypt_rng_device_count;
+static u32 *zcrypt_rng_buffer;
+static int zcrypt_rng_buffer_index;
+static DEFINE_MUTEX(zcrypt_rng_mutex);
+
+static int zcrypt_rng_data_read(struct hwrng *rng, u32 *data)
+{
+ int rc;
+
+ /**
+ * We don't need locking here because the RNG API guarantees serialized
+ * read method calls.
+ */
+ if (zcrypt_rng_buffer_index == 0) {
+ rc = zcrypt_rng((char *) zcrypt_rng_buffer);
+ if (rc < 0)
+ return -EIO;
+ zcrypt_rng_buffer_index = rc / sizeof *data;
+ }
+ *data = zcrypt_rng_buffer[--zcrypt_rng_buffer_index];
+ return sizeof *data;
+}
+
+static struct hwrng zcrypt_rng_dev = {
+ .name = "zcrypt",
+ .data_read = zcrypt_rng_data_read,
+};
+
+static int zcrypt_rng_device_add(void)
+{
+ int rc = 0;
+
+ mutex_lock(&zcrypt_rng_mutex);
+ if (zcrypt_rng_device_count == 0) {
+ zcrypt_rng_buffer = (u32 *) get_zeroed_page(GFP_KERNEL);
+ if (!zcrypt_rng_buffer) {
+ rc = -ENOMEM;
+ goto out;
+ }
+ zcrypt_rng_buffer_index = 0;
+ rc = hwrng_register(&zcrypt_rng_dev);
+ if (rc)
+ goto out_free;
+ zcrypt_rng_device_count = 1;
+ } else
+ zcrypt_rng_device_count++;
+ mutex_unlock(&zcrypt_rng_mutex);
+ return 0;
+
+out_free:
+ free_page((unsigned long) zcrypt_rng_buffer);
+out:
+ mutex_unlock(&zcrypt_rng_mutex);
+ return rc;
+}
+
+static void zcrypt_rng_device_remove(void)
+{
+ mutex_lock(&zcrypt_rng_mutex);
+ zcrypt_rng_device_count--;
+ if (zcrypt_rng_device_count == 0) {
+ hwrng_unregister(&zcrypt_rng_dev);
+ free_page((unsigned long) zcrypt_rng_buffer);
+ }
+ mutex_unlock(&zcrypt_rng_mutex);
+}
+
/**
* The module initialization code.
*/
Index: quilt-2.6/drivers/s390/crypto/zcrypt_api.h
===================================================================
--- quilt-2.6.orig/drivers/s390/crypto/zcrypt_api.h
+++ quilt-2.6/drivers/s390/crypto/zcrypt_api.h
@@ -100,6 +100,13 @@ struct ica_z90_status {
#define ZCRYPT_CEX2C 5
#define ZCRYPT_CEX2A 6

+/**
+ * Large random numbers are pulled in 4096 byte chunks from the crypto cards
+ * and stored in a page. Be carefull when increasing this buffer due to size
+ * limitations for AP requests.
+ */
+#define ZCRYPT_RNG_BUFFER_SIZE 4096
+
struct zcrypt_device;

struct zcrypt_ops {
@@ -107,6 +114,7 @@ struct zcrypt_ops {
long (*rsa_modexpo_crt)(struct zcrypt_device *,
struct ica_rsa_modexpo_crt *);
long (*send_cprb)(struct zcrypt_device *, struct ica_xcRB *);
+ long (*rng)(struct zcrypt_device *, char *);
};

struct zcrypt_device {
Index: quilt-2.6/drivers/s390/crypto/zcrypt_pcixcc.c
===================================================================
--- quilt-2.6.orig/drivers/s390/crypto/zcrypt_pcixcc.c
+++ quilt-2.6/drivers/s390/crypto/zcrypt_pcixcc.c
@@ -356,6 +356,55 @@ static int XCRB_msg_to_type6CPRB_msgX(st
}

/**
+ * Prepare a type6 CPRB message for random number generation
+ *
+ * @ap_dev: AP device pointer
+ * @ap_msg: pointer to AP message
+ */
+static void rng_type6CPRB_msgX(struct ap_device *ap_dev,
+ struct ap_message *ap_msg,
+ unsigned random_number_length)
+{
+ struct {
+ struct type6_hdr hdr;
+ struct CPRBX cprbx;
+ char function_code[2];
+ short int rule_length;
+ char rule[8];
+ short int verb_length;
+ short int key_length;
+ } __attribute__((packed)) *msg = ap_msg->message;
+ static struct type6_hdr static_type6_hdrX = {
+ .type = 0x06,
+ .offset1 = 0x00000058,
+ .agent_id = {'C', 'A'},
+ .function_code = {'R', 'L'},
+ .ToCardLen1 = sizeof *msg - sizeof(msg->hdr),
+ .FromCardLen1 = sizeof *msg - sizeof(msg->hdr),
+ };
+ static struct CPRBX static_cprbx = {
+ .cprb_len = 0x00dc,
+ .cprb_ver_id = 0x02,
+ .func_id = {0x54, 0x32},
+ .req_parml = sizeof *msg - sizeof(msg->hdr) -
+ sizeof(msg->cprbx),
+ .rpl_msgbl = sizeof *msg - sizeof(msg->hdr),
+ };
+
+ msg->hdr = static_type6_hdrX;
+ msg->hdr.FromCardLen2 = random_number_length,
+ msg->cprbx = static_cprbx;
+ msg->cprbx.rpl_datal = random_number_length,
+ msg->cprbx.domain = AP_QID_QUEUE(ap_dev->qid);
+ memcpy(msg->function_code, msg->hdr.function_code, 0x02);
+ msg->rule_length = 0x0a;
+ memcpy(msg->rule, "RANDOM ", 8);
+ msg->verb_length = 0x02;
+ msg->key_length = 0x02;
+ ap_msg->length = sizeof *msg;
+}
+
+/**
* Copy results from a type 86 ICA reply message back to user space.
*
* @zdev: crypto device pointer
@@ -509,6 +558,26 @@ static int convert_type86_xcrb(struct zc
return 0;
}

+static int convert_type86_rng(struct zcrypt_device *zdev,
+ struct ap_message *reply,
+ char *buffer)
+{
+ struct {
+ struct type86_hdr hdr;
+ struct type86_fmt2_ext fmt2;
+ struct CPRBX cprbx;
+ } __attribute__((packed)) *msg = reply->message;
+ char *data = reply->message;
+
+ if (msg->cprbx.ccp_rtcode != 0 || msg->cprbx.ccp_rscode != 0) {
+ PDEBUG("RNG response error on PCIXCC/CEX2C rc=%hu/rs=%hu\n",
+ rc, rs);
+ return -EINVAL;
+ }
+ memcpy(buffer, data + msg->fmt2.offset2, msg->fmt2.count2);
+ return msg->fmt2.count2;
+}
+
static int convert_response_ica(struct zcrypt_device *zdev,
struct ap_message *reply,
char __user *outputdata,
@@ -567,6 +636,31 @@ static int convert_response_xcrb(struct
}
}

+static int convert_response_rng(struct zcrypt_device *zdev,
+ struct ap_message *reply,
+ char *data)
+{
+ struct type86x_reply *msg = reply->message;
+
+ switch (msg->hdr.type) {
+ case TYPE82_RSP_CODE:
+ case TYPE88_RSP_CODE:
+ return -EINVAL;
+ case TYPE86_RSP_CODE:
+ if (msg->hdr.reply_code)
+ return -EINVAL;
+ if (msg->cprbx.cprb_ver_id == 0x02)
+ return convert_type86_rng(zdev, reply, data);
+ /* no break, incorrect cprb version is an unknown response */
+ default: /* Unknown response type, this should NEVER EVER happen */
+ PRINTK("Unrecognized Message Header: %08x%08x\n",
+ *(unsigned int *) reply->message,
+ *(unsigned int *) (reply->message+4));
+ zdev->online = 0;
+ return -EAGAIN; /* repeat the request on a different device. */
+ }
+}
+
/**
* This function is called from the AP bus code after a crypto request
* "msg" has finished with the reply message "reply".
@@ -736,6 +830,42 @@ out_free:
}

/**
+ * The request distributor calls this function if it picked the PCIXCC/CEX2C
+ * device to generate random data.
+ * @zdev: pointer to zcrypt_device structure that identifies the
+ * PCIXCC/CEX2C device to the request distributor
+ * @buffer: pointer to a memory page to return random data
+ */
+
+static long zcrypt_pcixcc_rng(struct zcrypt_device *zdev,
+ char *buffer)
+{
+ struct ap_message ap_msg;
+ struct response_type resp_type = {
+ .type = PCIXCC_RESPONSE_TYPE_XCRB,
+ };
+ int rc;
+
+ ap_msg.message = kmalloc(PCIXCC_MAX_XCRB_MESSAGE_SIZE, GFP_KERNEL);
+ if (!ap_msg.message)
+ return -ENOMEM;
+ ap_msg.psmid = (((unsigned long long) current->pid) << 32) +
+ atomic_inc_return(&zcrypt_step);
+ ap_msg.private = &resp_type;
+ rng_type6CPRB_msgX(zdev->ap_dev, &ap_msg, ZCRYPT_RNG_BUFFER_SIZE);
+ init_completion(&resp_type.work);
+ ap_queue_message(zdev->ap_dev, &ap_msg);
+ rc = wait_for_completion_interruptible(&resp_type.work);
+ if (rc == 0)
+ rc = convert_response_rng(zdev, &ap_msg, buffer);
+ else
+ /* Signal pending. */
+ ap_cancel_message(zdev->ap_dev, &ap_msg);
+ kfree(ap_msg.message);
+ return rc;
+}
+
+/**
* The crypto operations for a PCIXCC/CEX2C card.
*/
static struct zcrypt_ops zcrypt_pcixcc_ops = {
@@ -744,6 +874,13 @@ static struct zcrypt_ops zcrypt_pcixcc_o
.send_cprb = zcrypt_pcixcc_send_cprb,
};

+static struct zcrypt_ops zcrypt_pcixcc_with_rng_ops = {
+ .rsa_modexpo = zcrypt_pcixcc_modexpo,
+ .rsa_modexpo_crt = zcrypt_pcixcc_modexpo_crt,
+ .send_cprb = zcrypt_pcixcc_send_cprb,
+ .rng = zcrypt_pcixcc_rng,
+};
+
/**
* Micro-code detection function. Its sends a message to a pcixcc card
* to find out the microcode level.
@@ -859,6 +996,58 @@ out_free:
}

/**
+ * Large random number detection function. Its sends a message to a pcixcc
+ * card to find out if large random numbers are supported.
+ * @ap_dev: pointer to the AP device.
+ *
+ * Returns 1 if large random numbers are supported, 0 if not and < 0 on error.
+ */
+static int zcrypt_pcixcc_rng_supported(struct ap_device *ap_dev)
+{
+ struct ap_message ap_msg;
+ unsigned long long psmid;
+ struct {
+ struct type86_hdr hdr;
+ struct type86_fmt2_ext fmt2;
+ struct CPRBX cprbx;
+ } __attribute__((packed)) *reply;
+ int rc, i;
+
+ ap_msg.message = (void *) get_zeroed_page(GFP_KERNEL);
+ if (!ap_msg.message)
+ return -ENOMEM;
+
+ rng_type6CPRB_msgX(ap_dev, &ap_msg, 4);
+ rc = ap_send(ap_dev->qid, 0x0102030405060708ULL, ap_msg.message,
+ ap_msg.length);
+ if (rc)
+ goto out_free;
+
+ /* Wait for the test message to complete. */
+ for (i = 0; i < 2 * HZ; i++) {
+ msleep(1000 / HZ);
+ rc = ap_recv(ap_dev->qid, &psmid, ap_msg.message, 4096);
+ if (rc == 0 && psmid == 0x0102030405060708ULL)
+ break;
+ }
+
+ if (i >= 2 * HZ) {
+ /* Got no answer. */
+ rc = -ENODEV;
+ goto out_free;
+ }
+
+ reply = ap_msg.message;
+ if (reply->cprbx.ccp_rtcode == 0 && reply->cprbx.ccp_rscode == 0)
+ rc = 1;
+ else
+ rc = 0;
+out_free:
+ free_page((unsigned long) ap_msg.message);
+ return rc;
+}
+
+/**
* Probe function for PCIXCC/CEX2C cards. It always accepts the AP device
* since the bus_match already checked the hardware type. The PCIXCC
* cards come in two flavours: micro code level 2 and micro code level 3.
@@ -874,7 +1063,6 @@ static int zcrypt_pcixcc_probe(struct ap
if (!zdev)
return -ENOMEM;
zdev->ap_dev = ap_dev;
- zdev->ops = &zcrypt_pcixcc_ops;
zdev->online = 1;
if (ap_dev->device_type == AP_DEVICE_TYPE_PCIXCC) {
rc = zcrypt_pcixcc_mcl(ap_dev);
@@ -901,6 +1089,15 @@ static int zcrypt_pcixcc_probe(struct ap
zdev->min_mod_size = PCIXCC_MIN_MOD_SIZE;
zdev->max_mod_size = PCIXCC_MAX_MOD_SIZE;
}
+ rc = zcrypt_pcixcc_rng_supported(ap_dev);
+ if (rc < 0) {
+ zcrypt_device_free(zdev);
+ return rc;
+ }
+ if (rc)
+ zdev->ops = &zcrypt_pcixcc_with_rng_ops;
+ else
+ zdev->ops = &zcrypt_pcixcc_ops;
ap_dev->reply = &zdev->reply;
ap_dev->private = zdev;
rc = zcrypt_device_register(zdev);

--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.

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