crypto: api - Fix built-in testing dependency failures

When complex algorithms that depend on other algorithms are built
into the kernel, the order of registration must be done such that
the underlying algorithms are ready before the ones on top are
registered.  As otherwise they would fail during the self-test
which is required during registration.

In the past we have used subsystem initialisation ordering to
guarantee this.  The number of such precedence levels are limited
and they may cause ripple effects in other subsystems.

This patch solves this problem by delaying all self-tests during
boot-up for built-in algorithms.  They will be tested either when
something else in the kernel requests for them, or when we have
finished registering all built-in algorithms, whichever comes
earlier.

Reported-by: Vladis Dronov <vdronov@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 47 insertions, 5 deletions

diff --git a/crypto/api.c b/crypto/api.c
index c4eda56cff89..1cf1f03347cc 100644
--- a/crypto/api.c
+++ b/crypto/api.c
@@ -12,6 +12,7 @@
 
 #include <linux/err.h>
 #include <linux/errno.h>
+#include <linux/jump_label.h>
 #include <linux/kernel.h>
 #include <linux/kmod.h>
 #include <linux/module.h>
@@ -30,6 +31,8 @@ EXPORT_SYMBOL_GPL(crypto_alg_sem);
 BLOCKING_NOTIFIER_HEAD(crypto_chain);
 EXPORT_SYMBOL_GPL(crypto_chain);
 
+DEFINE_STATIC_KEY_FALSE(crypto_boot_test_finished);
+
 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg);
 
 struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
@@ -47,11 +50,6 @@ void crypto_mod_put(struct crypto_alg *alg)
 }
 EXPORT_SYMBOL_GPL(crypto_mod_put);
 
-static inline int crypto_is_test_larval(struct crypto_larval *larval)
-{
-	return larval->alg.cra_driver_name[0];
-}
-
 static struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type,
 					      u32 mask)
 {
@@ -163,11 +161,55 @@ void crypto_larval_kill(struct crypto_alg *alg)
 }
 EXPORT_SYMBOL_GPL(crypto_larval_kill);
 
+void crypto_wait_for_test(struct crypto_larval *larval)
+{
+	int err;
+
+	err = crypto_probing_notify(CRYPTO_MSG_ALG_REGISTER, larval->adult);
+	if (err != NOTIFY_STOP) {
+		if (WARN_ON(err != NOTIFY_DONE))
+			goto out;
+		crypto_alg_tested(larval->alg.cra_driver_name, 0);
+	}
+
+	err = wait_for_completion_killable(&larval->completion);
+	WARN_ON(err);
+	if (!err)
+		crypto_notify(CRYPTO_MSG_ALG_LOADED, larval);
+
+out:
+	crypto_larval_kill(&larval->alg);
+}
+EXPORT_SYMBOL_GPL(crypto_wait_for_test);
+
+static void crypto_start_test(struct crypto_larval *larval)
+{
+	if (!crypto_is_test_larval(larval))
+		return;
+
+	if (larval->test_started)
+		return;
+
+	down_write(&crypto_alg_sem);
+	if (larval->test_started) {
+		up_write(&crypto_alg_sem);
+		return;
+	}
+
+	larval->test_started = true;
+	up_write(&crypto_alg_sem);
+
+	crypto_wait_for_test(larval);
+}
+
 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
 {
 	struct crypto_larval *larval = (void *)alg;
 	long timeout;
 
+	if (!static_branch_likely(&crypto_boot_test_finished))
+		crypto_start_test(larval);
+
 	timeout = wait_for_completion_killable_timeout(
 		&larval->completion, 60 * HZ);