[PATCH 01/31] crypto: Introduce crypto_pool

Dmitry Safonov
2022-08-18T17:01:10Z

Introduce a per-CPU pool of async crypto requests that can be used
in bh-disabled contexts (designed with net RX/TX softirqs as users in
mind). Allocation can sleep and is a slow-path.
Initial implementation has only ahash as a backend and a fix-sized array
of possible algorithms used in parallel.

Signed-off-by: Dmitry Safonov <dima@arista.com>
---
crypto/Kconfig | 6 +
crypto/Makefile | 1 +
crypto/crypto_pool.c | 291 ++++++++++++++++++++++++++++++++++++++++++
include/crypto/pool.h | 34 +++++
4 files changed, 332 insertions(+)
create mode 100644 crypto/crypto_pool.c
create mode 100644 include/crypto/pool.h

diff --git a/crypto/Kconfig b/crypto/Kconfig
index bb427a835e44..aeddaa3dcc77 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -2128,6 +2128,12 @@ config CRYPTO_STATS
config CRYPTO_HASH_INFO
bool

+config CRYPTO_POOL
+ tristate "Per-CPU crypto pool"
+ default n
+ help
+ Per-CPU pool of crypto requests ready for usage in atomic contexts.
+
source "drivers/crypto/Kconfig"
source "crypto/asymmetric_keys/Kconfig"
source "certs/Kconfig"
diff --git a/crypto/Makefile b/crypto/Makefile
index a6f94e04e1da..b0f54cb9cea1 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -63,6 +63,7 @@ obj-$(CONFIG_CRYPTO_ACOMP2) += crypto_acompress.o
cryptomgr-y := algboss.o testmgr.o

obj-$(CONFIG_CRYPTO_MANAGER2) += cryptomgr.o
+obj-$(CONFIG_CRYPTO_POOL) += crypto_pool.o
obj-$(CONFIG_CRYPTO_USER) += crypto_user.o
crypto_user-y := crypto_user_base.o
crypto_user-$(CONFIG_CRYPTO_STATS) += crypto_user_stat.o
diff --git a/crypto/crypto_pool.c b/crypto/crypto_pool.c
new file mode 100644
index 000000000000..a5b6e6cf818a
--- /dev/null
+++ b/crypto/crypto_pool.c
@@ -0,0 +1,291 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <crypto/pool.h>
+#include <linux/kref.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/percpu.h>
+#include <linux/workqueue.h>
+
+static unsigned long scratch_size = DEFAULT_CRYPTO_POOL_SCRATCH_SZ;
+static DEFINE_PER_CPU(void *, crypto_pool_scratch);
+
+struct crypto_pool_entry {
+ struct ahash_request * __percpu *req;
+ const char *alg;
+ struct kref kref;
+ bool needs_key;
+};
+
+#define CPOOL_SIZE (PAGE_SIZE/sizeof(struct crypto_pool_entry))
+static struct crypto_pool_entry cpool[CPOOL_SIZE];
+static int last_allocated;
+static DEFINE_MUTEX(cpool_mutex);
+
+static int crypto_pool_scratch_alloc(void)
+{
+ int cpu;
+
+ lockdep_assert_held(&cpool_mutex);
+
+ for_each_possible_cpu(cpu) {
+ void *scratch = per_cpu(crypto_pool_scratch, cpu);
+
+ if (scratch)
+ continue;
+
+ scratch = kmalloc_node(scratch_size, GFP_KERNEL,
+ cpu_to_node(cpu));
+ if (!scratch)
+ return -ENOMEM;
+ per_cpu(crypto_pool_scratch, cpu) = scratch;
+ }
+ return 0;
+}
+
+static void crypto_pool_scratch_free(void)
+{
+ int cpu;
+
+ lockdep_assert_held(&cpool_mutex);
+
+ for_each_possible_cpu(cpu) {
+ void *scratch = per_cpu(crypto_pool_scratch, cpu);
+
+ if (!scratch)
+ continue;
+ per_cpu(crypto_pool_scratch, cpu) = NULL;
+ kfree(scratch);
+ }
+}
+
+static int __cpool_alloc_ahash(struct crypto_pool_entry *e, const char *alg)
+{
+ struct crypto_ahash *hash;
+ int cpu, ret = -ENOMEM;
+
+ e->alg = kstrdup(alg, GFP_KERNEL);
+ if (!e->alg)
+ return -ENOMEM;
+
+ e->req = alloc_percpu(struct ahash_request *);
+ if (!e->req)
+ goto out_free_alg;
+
+ hash = crypto_alloc_ahash(alg, 0, CRYPTO_ALG_ASYNC);
+ if (IS_ERR(hash)) {
+ ret = PTR_ERR(hash);
+ goto out_free_req;
+ }
+
+ /* If hash has .setkey(), allocate ahash per-cpu, not only request */
+ e->needs_key = crypto_ahash_get_flags(hash) & CRYPTO_TFM_NEED_KEY;
+
+ for_each_possible_cpu(cpu) {
+ struct ahash_request *req;
+
+ if (!hash)
+ hash = crypto_alloc_ahash(alg, 0, CRYPTO_ALG_ASYNC);
+ if (IS_ERR(hash))
+ goto out_free;
+
+ req = ahash_request_alloc(hash, GFP_KERNEL);
+ if (!req)
+ goto out_free;
+
+ ahash_request_set_callback(req, 0, NULL, NULL);
+
+ *per_cpu_ptr(e->req, cpu) = req;
+
+ if (e->needs_key)
+ hash = NULL;
+ }
+ kref_init(&e->kref);
+ return 0;
+
+out_free:
+ if (!IS_ERR_OR_NULL(hash) && e->needs_key)
+ crypto_free_ahash(hash);
+
+ for_each_possible_cpu(cpu) {
+ if (*per_cpu_ptr(e->req, cpu) == NULL)
+ break;
+ hash = crypto_ahash_reqtfm(*per_cpu_ptr(e->req, cpu));
+ ahash_request_free(*per_cpu_ptr(e->req, cpu));
+ if (e->needs_key) {
+ crypto_free_ahash(hash);
+ hash = NULL;
+ }
+ }
+
+ if (hash)
+ crypto_free_ahash(hash);
+out_free_req:
+ free_percpu(e->req);
+out_free_alg:
+ kfree(e->alg);
+ e->alg = NULL;
+ return ret;
+}
+
+/**
+ * crypto_pool_alloc_ahash - allocates pool for ahash requests
+ * @alg: name of async hash algorithm
+ */
+int crypto_pool_alloc_ahash(const char *alg)
+{
+ unsigned int i;
+ int err;
+
+ /* slow-path */
+ mutex_lock(&cpool_mutex);
+ err = crypto_pool_scratch_alloc();
+ if (err)
+ goto out;
+
+ for (i = 0; i < last_allocated; i++) {
+ if (cpool[i].alg && !strcmp(cpool[i].alg, alg)) {
+ if (kref_read(&cpool[i].kref) > 0) {
+ kref_get(&cpool[i].kref);
+ goto out;
+ } else {
+ break;
+ }
+ }
+ }
+
+ for (i = 0; i < last_allocated; i++) {
+ if (!cpool[i].alg)
+ break;
+ }
+ if (i >= CPOOL_SIZE) {
+ err = -ENOSPC;
+ goto out;
+ }
+
+ err = __cpool_alloc_ahash(&cpool[i], alg);
+ if (!err && last_allocated <= i)
+ last_allocated++;
+out:
+ mutex_unlock(&cpool_mutex);
+ return err ?: (int)i;
+}
+EXPORT_SYMBOL_GPL(crypto_pool_alloc_ahash);
+
+static void __cpool_free_entry(struct crypto_pool_entry *e)
+{
+ struct crypto_ahash *hash = NULL;
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ if (*per_cpu_ptr(e->req, cpu) == NULL)
+ continue;
+
+ hash = crypto_ahash_reqtfm(*per_cpu_ptr(e->req, cpu));
+ ahash_request_free(*per_cpu_ptr(e->req, cpu));
+ if (e->needs_key) {
+ crypto_free_ahash(hash);
+ hash = NULL;
+ }
+ }
+ if (hash)
+ crypto_free_ahash(hash);
+ free_percpu(e->req);
+ kfree(e->alg);
+ memset(e, 0, sizeof(*e));
+}
+
+static void cpool_cleanup_work_cb(struct work_struct *work)
+{
+ unsigned int i;
+ bool free_scratch = true;
+
+ mutex_lock(&cpool_mutex);
+ for (i = 0; i < last_allocated; i++) {
+ if (kref_read(&cpool[i].kref) > 0) {
+ free_scratch = false;
+ continue;
+ }
+ if (!cpool[i].alg)
+ continue;
+ __cpool_free_entry(&cpool[i]);
+ }
+ if (free_scratch)
+ crypto_pool_scratch_free();
+ mutex_unlock(&cpool_mutex);
+}
+
+static DECLARE_WORK(cpool_cleanup_work, cpool_cleanup_work_cb);
+static void cpool_schedule_cleanup(struct kref *kref)
+{
+ schedule_work(&cpool_cleanup_work);
+}
+
+/**
+ * crypto_pool_release - decreases number of users for a pool. If it was
+ * the last user of the pool, releases any memory that was consumed.
+ * @id: crypto_pool that was previously allocated by crypto_pool_alloc_ahash()
+ */
+void crypto_pool_release(unsigned int id)
+{
+ if (WARN_ON_ONCE(id > last_allocated || !cpool[id].alg))
+ return;
+
+ /* slow-path */
+ kref_put(&cpool[id].kref, cpool_schedule_cleanup);
+}
+EXPORT_SYMBOL_GPL(crypto_pool_release);
+
+/**
+ * crypto_pool_add - increases number of users (refcounter) for a pool
+ * @id: crypto_pool that was previously allocated by crypto_pool_alloc_ahash()
+ */
+void crypto_pool_add(unsigned int id)
+{
+ if (WARN_ON_ONCE(id > last_allocated || !cpool[id].alg))
+ return;
+ kref_get(&cpool[id].kref);
+}
+EXPORT_SYMBOL_GPL(crypto_pool_add);
+
+/**
+ * crypto_pool_get - disable bh and start using crypto_pool
+ * @id: crypto_pool that was previously allocated by crypto_pool_alloc_ahash()
+ * @c: returned crypto_pool for usage (uninitialized on failure)
+ */
+int crypto_pool_get(unsigned int id, struct crypto_pool *c)
+{
+ struct crypto_pool_ahash *ret = (struct crypto_pool_ahash *)c;
+
+ local_bh_disable();
+ if (WARN_ON_ONCE(id > last_allocated || !cpool[id].alg)) {
+ local_bh_enable();
+ return -EINVAL;
+ }
+ ret->req = *this_cpu_ptr(cpool[id].req);
+ ret->base.scratch = this_cpu_read(crypto_pool_scratch);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(crypto_pool_get);
+
+/**
+ * crypto_pool_algo - return algorithm of crypto_pool
+ * @id: crypto_pool that was previously allocated by crypto_pool_alloc_ahash()
+ * @buf: buffer to return name of algorithm
+ * @buf_len: size of @buf
+ */
+size_t crypto_pool_algo(unsigned int id, char *buf, size_t buf_len)
+{
+ size_t ret = 0;
+
+ /* slow-path */
+ mutex_lock(&cpool_mutex);
+ if (cpool[id].alg)
+ ret = strscpy(buf, cpool[id].alg, buf_len);
+ mutex_unlock(&cpool_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(crypto_pool_algo);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Per-CPU pool of crypto requests");
diff --git a/include/crypto/pool.h b/include/crypto/pool.h
new file mode 100644
index 000000000000..2c61aa45faff
--- /dev/null
+++ b/include/crypto/pool.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _CRYPTO_POOL_H
+#define _CRYPTO_POOL_H
+
+#include <crypto/hash.h>
+
+#define DEFAULT_CRYPTO_POOL_SCRATCH_SZ 128
+
+struct crypto_pool {
+ void *scratch;
+};
+
+/*
+ * struct crypto_pool_ahash - per-CPU pool of ahash_requests
+ * @base: common members that can be used by any async crypto ops
+ * @req: pre-allocated ahash request
+ */
+struct crypto_pool_ahash {
+ struct crypto_pool base;
+ struct ahash_request *req;
+};
+
+int crypto_pool_alloc_ahash(const char *alg);
+void crypto_pool_add(unsigned int id);
+void crypto_pool_release(unsigned int id);
+
+int crypto_pool_get(unsigned int id, struct crypto_pool *c);
+static inline void crypto_pool_put(void)
+{
+ local_bh_enable();
+}
+size_t crypto_pool_algo(unsigned int id, char *buf, size_t buf_len);
+
+#endif /* _CRYPTO_POOL_H */
--
2.37.2