[PATCH v4 07/24] s390/zcrypt: Introduce cprb mempool for ep11 misc functions

Harald Freudenberger
2025-04-09T14:03:18Z

Introduce a cprb mempool for the zcrypt ep11 misc functions
(zcrypt_ep11misc.*) do some preparation rework to support
a do-not-allocate path through some zcrypt ep11 misc functions.

The mempool is controlled by the zcrypt module parameter
"mempool_threshold" which shall control the minimal amount
of memory items for CCA and EP11.

The mempool shall support "mempool_threshold" requests/replies
in parallel which means for EP11 to hold a send and receive
buffer memory per request. Each of this cprb space items is
limited to 8 KB. So by default the mempool consumes
5 * 2 * 8KB = 80KB

If the mempool is depleted upon one ep11 misc functions is
called with the ZCRYPT_XFLAG_NOMEMALLOC xflag set, the function
will fail with -ENOMEM and the caller is responsible for taking
further actions.

This is only part of an rework to support a new xflag
ZCRYPT_XFLAG_NOMEMALLOC but not yet complete.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
---
drivers/s390/crypto/zcrypt_api.c | 6 +
drivers/s390/crypto/zcrypt_ep11misc.c | 153 ++++++++++++++++----------
drivers/s390/crypto/zcrypt_ep11misc.h | 1 +
3 files changed, 99 insertions(+), 61 deletions(-)

diff --git a/drivers/s390/crypto/zcrypt_api.c b/drivers/s390/crypto/zcrypt_api.c
index 888ab289bd10..95b9e6200ce2 100644
--- a/drivers/s390/crypto/zcrypt_api.c
+++ b/drivers/s390/crypto/zcrypt_api.c
@@ -2166,6 +2166,10 @@ int __init zcrypt_api_init(void)
if (rc)
goto out_ccamisc_init_failed;

+ rc = zcrypt_ep11misc_init();
+ if (rc)
+ goto out_ep11misc_init_failed;
+
/* Register the request sprayer. */
rc = misc_register(&zcrypt_misc_device);
if (rc < 0)
@@ -2177,6 +2181,8 @@ int __init zcrypt_api_init(void)
return 0;

out_misc_register_failed:
+ zcrypt_ep11misc_exit();
+out_ep11misc_init_failed:
zcrypt_ccamisc_exit();
out_ccamisc_init_failed:
zcdn_exit();
diff --git a/drivers/s390/crypto/zcrypt_ep11misc.c b/drivers/s390/crypto/zcrypt_ep11misc.c
index b60e262bcaa3..00e9d141a456 100644
--- a/drivers/s390/crypto/zcrypt_ep11misc.c
+++ b/drivers/s390/crypto/zcrypt_ep11misc.c
@@ -10,9 +10,10 @@
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/init.h>
+#include <linux/mempool.h>
#include <linux/module.h>
-#include <linux/slab.h>
#include <linux/random.h>
+#include <linux/slab.h>
#include <asm/zcrypt.h>
#include <asm/pkey.h>
#include <crypto/aes.h>
@@ -30,6 +31,14 @@
static const u8 def_iv[16] = { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff };

+/*
+ * Cprb memory pool held for urgent cases where no memory
+ * can be allocated via kmalloc. This pool is only used when
+ * alloc_cprbmem() is called with the xflag ZCRYPT_XFLAG_NOMEMALLOC.
+ */
+#define CPRB_MEMPOOL_ITEM_SIZE (8 * 1024)
+static mempool_t *cprb_mempool;
+
/* ep11 card info cache */
struct card_list_entry {
struct list_head list;
@@ -411,12 +420,19 @@ EXPORT_SYMBOL(ep11_check_aes_key);
/*
* Allocate and prepare ep11 cprb plus additional payload.
*/
-static inline struct ep11_cprb *alloc_cprb(size_t payload_len)
+static void *alloc_cprbmem(size_t payload_len, u32 xflags)
{
size_t len = sizeof(struct ep11_cprb) + payload_len;
- struct ep11_cprb *cprb;
+ struct ep11_cprb *cprb = NULL;

- cprb = kzalloc(len, GFP_KERNEL);
+ if (xflags & ZCRYPT_XFLAG_NOMEMALLOC) {
+ if (cprb_mempool && len <= CPRB_MEMPOOL_ITEM_SIZE) {
+ cprb = mempool_alloc_preallocated(cprb_mempool);
+ memset(cprb, 0, len);
+ }
+ } else {
+ cprb = kzalloc(len, GFP_KERNEL);
+ }
if (!cprb)
return NULL;

@@ -429,6 +445,20 @@ static inline struct ep11_cprb *alloc_cprb(size_t payload_len)
return cprb;
}

+/*
+ * Free ep11 cprb buffer space.
+ */
+static void free_cprbmem(void *mem, size_t payload_len, bool scrub, u32 xflags)
+{
+ if (scrub)
+ memzero_explicit(mem, sizeof(struct ep11_cprb) + payload_len);
+
+ if (xflags & ZCRYPT_XFLAG_NOMEMALLOC)
+ mempool_free(mem, cprb_mempool);
+ else
+ kfree(mem);
+}
+
/*
* Some helper functions related to ASN1 encoding.
* Limited to length info <= 2 byte.
@@ -489,6 +519,7 @@ static inline void prep_urb(struct ep11_urb *u,
struct ep11_cprb *req, size_t req_len,
struct ep11_cprb *rep, size_t rep_len)
{
+ memset(u, 0, sizeof(*u));
u->targets = (u8 __user *)t;
u->targets_num = nt;
u->req = (u8 __user *)req;
@@ -605,11 +636,12 @@ static int ep11_query_info(u16 cardnr, u16 domain, u32 query_type,
} __packed * rep_pl;
struct ep11_cprb *req = NULL, *rep = NULL;
struct ep11_target_dev target;
- struct ep11_urb *urb = NULL;
+ struct ep11_urb urb;
int api = EP11_API_V1, rc = -ENOMEM;
+ const u32 xflags = 0;

/* request cprb and payload */
- req = alloc_cprb(sizeof(struct ep11_info_req_pl));
+ req = alloc_cprbmem(sizeof(struct ep11_info_req_pl), xflags);
if (!req)
goto out;
req_pl = (struct ep11_info_req_pl *)(((u8 *)req) + sizeof(*req));
@@ -621,22 +653,19 @@ static int ep11_query_info(u16 cardnr, u16 domain, u32 query_type,
req_pl->query_subtype_len = sizeof(u32);

/* reply cprb and payload */
- rep = alloc_cprb(sizeof(struct ep11_info_rep_pl) + buflen);
+ rep = alloc_cprbmem(sizeof(struct ep11_info_rep_pl) + buflen, xflags);
if (!rep)
goto out;
rep_pl = (struct ep11_info_rep_pl *)(((u8 *)rep) + sizeof(*rep));

/* urb and target */
- urb = kmalloc(sizeof(*urb), GFP_KERNEL);
- if (!urb)
- goto out;
target.ap_id = cardnr;
target.dom_id = domain;
- prep_urb(urb, &target, 1,
+ prep_urb(&urb, &target, 1,
req, sizeof(*req) + sizeof(*req_pl),
rep, sizeof(*rep) + sizeof(*rep_pl) + buflen);

- rc = zcrypt_send_ep11_cprb(urb, 0);
+ rc = zcrypt_send_ep11_cprb(&urb, xflags);
if (rc) {
ZCRYPT_DBF_ERR("%s zcrypt_send_ep11_cprb(card=%d dom=%d) failed, rc=%d\n",
__func__, (int)cardnr, (int)domain, rc);
@@ -667,9 +696,8 @@ static int ep11_query_info(u16 cardnr, u16 domain, u32 query_type,
memcpy(buf, ((u8 *)rep_pl) + sizeof(*rep_pl), rep_pl->data_len);

out:
- kfree(req);
- kfree(rep);
- kfree(urb);
+ free_cprbmem(req, 0, false, xflags);
+ free_cprbmem(rep, 0, false, xflags);
return rc;
}

@@ -823,9 +851,10 @@ static int _ep11_genaeskey(u16 card, u16 domain,
struct ep11_cprb *req = NULL, *rep = NULL;
size_t req_pl_size, pinblob_size = 0;
struct ep11_target_dev target;
- struct ep11_urb *urb = NULL;
+ struct ep11_urb urb;
int api, rc = -ENOMEM;
u8 *p;
+ const u32 xflags = 0;

switch (keybitsize) {
case 128:
@@ -851,7 +880,7 @@ static int _ep11_genaeskey(u16 card, u16 domain,
pinblob_size = EP11_PINBLOB_V1_BYTES;
}
req_pl_size = sizeof(struct keygen_req_pl) + ASN1TAGLEN(pinblob_size);
- req = alloc_cprb(req_pl_size);
+ req = alloc_cprbmem(req_pl_size, xflags);
if (!req)
goto out;
req_pl = (struct keygen_req_pl *)(((u8 *)req) + sizeof(*req));
@@ -877,22 +906,19 @@ static int _ep11_genaeskey(u16 card, u16 domain,
*p++ = pinblob_size;

/* reply cprb and payload */
- rep = alloc_cprb(sizeof(struct keygen_rep_pl));
+ rep = alloc_cprbmem(sizeof(struct keygen_rep_pl), xflags);
if (!rep)
goto out;
rep_pl = (struct keygen_rep_pl *)(((u8 *)rep) + sizeof(*rep));

/* urb and target */
- urb = kmalloc(sizeof(*urb), GFP_KERNEL);
- if (!urb)
- goto out;
target.ap_id = card;
target.dom_id = domain;
- prep_urb(urb, &target, 1,
+ prep_urb(&urb, &target, 1,
req, sizeof(*req) + req_pl_size,
rep, sizeof(*rep) + sizeof(*rep_pl));

- rc = zcrypt_send_ep11_cprb(urb, 0);
+ rc = zcrypt_send_ep11_cprb(&urb, xflags);
if (rc) {
ZCRYPT_DBF_ERR("%s zcrypt_send_ep11_cprb(card=%d dom=%d) failed, rc=%d\n",
__func__, (int)card, (int)domain, rc);
@@ -925,9 +951,8 @@ static int _ep11_genaeskey(u16 card, u16 domain,
*keybufsize = rep_pl->data_len;

out:
- kfree(req);
- kfree(rep);
- kfree(urb);
+ free_cprbmem(req, 0, false, xflags);
+ free_cprbmem(rep, sizeof(struct keygen_rep_pl), true, xflags);
return rc;
}

@@ -1000,10 +1025,11 @@ static int ep11_cryptsingle(u16 card, u16 domain,
} __packed * rep_pl;
struct ep11_cprb *req = NULL, *rep = NULL;
struct ep11_target_dev target;
- struct ep11_urb *urb = NULL;
+ struct ep11_urb urb;
size_t req_pl_size, rep_pl_size;
int n, api = EP11_API_V1, rc = -ENOMEM;
u8 *p;
+ const u32 xflags = 0;

/* the simple asn1 coding used has length limits */
if (keysize > 0xFFFF || inbufsize > 0xFFFF)
@@ -1012,7 +1038,7 @@ static int ep11_cryptsingle(u16 card, u16 domain,
/* request cprb and payload */
req_pl_size = sizeof(struct crypt_req_pl) + (iv ? 16 : 0)
+ ASN1TAGLEN(keysize) + ASN1TAGLEN(inbufsize);
- req = alloc_cprb(req_pl_size);
+ req = alloc_cprbmem(req_pl_size, xflags);
if (!req)
goto out;
req_pl = (struct crypt_req_pl *)(((u8 *)req) + sizeof(*req));
@@ -1034,22 +1060,19 @@ static int ep11_cryptsingle(u16 card, u16 domain,

/* reply cprb and payload, assume out data size <= in data size + 32 */
rep_pl_size = sizeof(struct crypt_rep_pl) + ASN1TAGLEN(inbufsize + 32);
- rep = alloc_cprb(rep_pl_size);
+ rep = alloc_cprbmem(rep_pl_size, xflags);
if (!rep)
goto out;
rep_pl = (struct crypt_rep_pl *)(((u8 *)rep) + sizeof(*rep));

/* urb and target */
- urb = kmalloc(sizeof(*urb), GFP_KERNEL);
- if (!urb)
- goto out;
target.ap_id = card;
target.dom_id = domain;
- prep_urb(urb, &target, 1,
+ prep_urb(&urb, &target, 1,
req, sizeof(*req) + req_pl_size,
rep, sizeof(*rep) + rep_pl_size);

- rc = zcrypt_send_ep11_cprb(urb, 0);
+ rc = zcrypt_send_ep11_cprb(&urb, xflags);
if (rc) {
ZCRYPT_DBF_ERR("%s zcrypt_send_ep11_cprb(card=%d dom=%d) failed, rc=%d\n",
__func__, (int)card, (int)domain, rc);
@@ -1095,9 +1118,8 @@ static int ep11_cryptsingle(u16 card, u16 domain,
*outbufsize = n;

out:
- kfree(req);
- kfree(rep);
- kfree(urb);
+ free_cprbmem(req, req_pl_size, true, xflags);
+ free_cprbmem(rep, rep_pl_size, true, xflags);
return rc;
}

@@ -1143,9 +1165,10 @@ static int _ep11_unwrapkey(u16 card, u16 domain,
struct ep11_cprb *req = NULL, *rep = NULL;
size_t req_pl_size, pinblob_size = 0;
struct ep11_target_dev target;
- struct ep11_urb *urb = NULL;
+ struct ep11_urb urb;
int api, rc = -ENOMEM;
u8 *p;
+ const u32 xflags = 0;

/* request cprb and payload */
api = (!keygenflags || keygenflags & 0x00200000) ?
@@ -1161,7 +1184,7 @@ static int _ep11_unwrapkey(u16 card, u16 domain,
req_pl_size = sizeof(struct uw_req_pl) + (iv ? 16 : 0)
+ ASN1TAGLEN(keksize) + ASN1TAGLEN(0)
+ ASN1TAGLEN(pinblob_size) + ASN1TAGLEN(enckeysize);
- req = alloc_cprb(req_pl_size);
+ req = alloc_cprbmem(req_pl_size, xflags);
if (!req)
goto out;
req_pl = (struct uw_req_pl *)(((u8 *)req) + sizeof(*req));
@@ -1197,22 +1220,19 @@ static int _ep11_unwrapkey(u16 card, u16 domain,
p += asn1tag_write(p, 0x04, enckey, enckeysize);

/* reply cprb and payload */
- rep = alloc_cprb(sizeof(struct uw_rep_pl));
+ rep = alloc_cprbmem(sizeof(struct uw_rep_pl), xflags);
if (!rep)
goto out;
rep_pl = (struct uw_rep_pl *)(((u8 *)rep) + sizeof(*rep));

/* urb and target */
- urb = kmalloc(sizeof(*urb), GFP_KERNEL);
- if (!urb)
- goto out;
target.ap_id = card;
target.dom_id = domain;
- prep_urb(urb, &target, 1,
+ prep_urb(&urb, &target, 1,
req, sizeof(*req) + req_pl_size,
rep, sizeof(*rep) + sizeof(*rep_pl));

- rc = zcrypt_send_ep11_cprb(urb, 0);
+ rc = zcrypt_send_ep11_cprb(&urb, xflags);
if (rc) {
ZCRYPT_DBF_ERR("%s zcrypt_send_ep11_cprb(card=%d dom=%d) failed, rc=%d\n",
__func__, (int)card, (int)domain, rc);
@@ -1245,9 +1265,8 @@ static int _ep11_unwrapkey(u16 card, u16 domain,
*keybufsize = rep_pl->data_len;

out:
- kfree(req);
- kfree(rep);
- kfree(urb);
+ free_cprbmem(req, req_pl_size, true, xflags);
+ free_cprbmem(rep, sizeof(struct uw_rep_pl), true, xflags);
return rc;
}

@@ -1319,15 +1338,16 @@ static int _ep11_wrapkey(u16 card, u16 domain,
} __packed * rep_pl;
struct ep11_cprb *req = NULL, *rep = NULL;
struct ep11_target_dev target;
- struct ep11_urb *urb = NULL;
+ struct ep11_urb urb;
size_t req_pl_size;
int api, rc = -ENOMEM;
u8 *p;
+ const u32 xflags = 0;

/* request cprb and payload */
req_pl_size = sizeof(struct wk_req_pl) + (iv ? 16 : 0)
+ ASN1TAGLEN(keysize) + 4;
- req = alloc_cprb(req_pl_size);
+ req = alloc_cprbmem(req_pl_size, xflags);
if (!req)
goto out;
if (!mech || mech == 0x80060001)
@@ -1357,22 +1377,19 @@ static int _ep11_wrapkey(u16 card, u16 domain,
*p++ = 0;

/* reply cprb and payload */
- rep = alloc_cprb(sizeof(struct wk_rep_pl));
+ rep = alloc_cprbmem(sizeof(struct wk_rep_pl), xflags);
if (!rep)
goto out;
rep_pl = (struct wk_rep_pl *)(((u8 *)rep) + sizeof(*rep));

/* urb and target */
- urb = kmalloc(sizeof(*urb), GFP_KERNEL);
- if (!urb)
- goto out;
target.ap_id = card;
target.dom_id = domain;
- prep_urb(urb, &target, 1,
+ prep_urb(&urb, &target, 1,
req, sizeof(*req) + req_pl_size,
rep, sizeof(*rep) + sizeof(*rep_pl));

- rc = zcrypt_send_ep11_cprb(urb, 0);
+ rc = zcrypt_send_ep11_cprb(&urb, xflags);
if (rc) {
ZCRYPT_DBF_ERR("%s zcrypt_send_ep11_cprb(card=%d dom=%d) failed, rc=%d\n",
__func__, (int)card, (int)domain, rc);
@@ -1405,9 +1422,8 @@ static int _ep11_wrapkey(u16 card, u16 domain,
*datasize = rep_pl->data_len;

out:
- kfree(req);
- kfree(rep);
- kfree(urb);
+ free_cprbmem(req, req_pl_size, true, xflags);
+ free_cprbmem(rep, sizeof(struct wk_rep_pl), true, xflags);
return rc;
}

@@ -1459,7 +1475,7 @@ int ep11_clr2keyblob(u16 card, u16 domain, u32 keybitsize, u32 keygenflags,
encbuf, encbuflen, 0, def_iv,
keybitsize, 0, keybuf, keybufsize, keytype);
if (rc) {
- ZCRYPT_DBF_ERR("%s importing key value as new key failed,, rc=%d\n",
+ ZCRYPT_DBF_ERR("%s importing key value as new key failed, rc=%d\n",
__func__, rc);
goto out;
}
@@ -1658,7 +1674,22 @@ int ep11_findcard2(u32 **apqns, u32 *nr_apqns, u16 cardnr, u16 domain,
}
EXPORT_SYMBOL(ep11_findcard2);

-void __exit zcrypt_ep11misc_exit(void)
+int __init zcrypt_ep11misc_init(void)
+{
+ /* Pre-allocate a small memory pool for ep11 cprbs. */
+ cprb_mempool = mempool_create_kmalloc_pool(2 * zcrypt_mempool_threshold,
+ CPRB_MEMPOOL_ITEM_SIZE);
+ if (!cprb_mempool) {
+ ZCRYPT_DBF_WARN("%s mempool_create(%d,%d) failed: %ld\n",
+ __func__, 2 * zcrypt_mempool_threshold,
+ CPRB_MEMPOOL_ITEM_SIZE, PTR_ERR(cprb_mempool));
+ return -ENOMEM;
+ }
+ return 0;
+}
+
+void zcrypt_ep11misc_exit(void)
{
card_cache_free();
+ mempool_destroy(cprb_mempool);
}
diff --git a/drivers/s390/crypto/zcrypt_ep11misc.h b/drivers/s390/crypto/zcrypt_ep11misc.h
index 9f1bdffdec68..a4b98eca8431 100644
--- a/drivers/s390/crypto/zcrypt_ep11misc.h
+++ b/drivers/s390/crypto/zcrypt_ep11misc.h
@@ -152,6 +152,7 @@ int ep11_findcard2(u32 **apqns, u32 *nr_apqns, u16 cardnr, u16 domain,
int ep11_kblob2protkey(u16 card, u16 dom, const u8 *key, u32 keylen,
u8 *protkey, u32 *protkeylen, u32 *protkeytype);

+int zcrypt_ep11misc_init(void);
void zcrypt_ep11misc_exit(void);

#endif /* _ZCRYPT_EP11MISC_H_ */
--
2.43.0