[RFC PATCH 1/5] crypto: aead - disallow en/decrypt for non-task or non-softirq context

[Ard Biesheuvel]

In order to ensure that kernel mode SIMD routines will not need a scalar
fallback if they run with softirqs disabled, disallow any use of the
AEAD encrypt and decrypt routines from outside of task or softirq context.

Signed-off-by: Ard Biesheuvel <a...@kernel.org>
---
 crypto/aead.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/crypto/aead.c b/crypto/aead.c
index 16991095270d..b5304b3d3314 100644
--- a/crypto/aead.c
+++ b/crypto/aead.c
@@ -87,6 +87,11 @@ int crypto_aead_encrypt(struct aead_request *req)
        unsigned int cryptlen = req->cryptlen;
        int ret;
 
+       if (!(alg->cra_flags & CRYPTO_ALG_ASYNC) &&
+           WARN_ONCE(!in_task() && !in_serving_softirq(),
+                     "synchronous call from invalid context\n"))
+               return -EBUSY;
+
        crypto_stats_get(alg);
        if (crypto_aead_get_flags(aead) & CRYPTO_TFM_NEED_KEY)
                ret = -ENOKEY;
@@ -104,6 +109,11 @@ int crypto_aead_decrypt(struct aead_request *req)
        unsigned int cryptlen = req->cryptlen;
        int ret;
 
+       if (!(alg->cra_flags & CRYPTO_ALG_ASYNC) &&
+           WARN_ONCE(!in_task() && !in_serving_softirq(),
+                     "synchronous call from invalid context\n"))
+               return -EBUSY;
+
        crypto_stats_get(alg);
        if (crypto_aead_get_flags(aead) & CRYPTO_TFM_NEED_KEY)
                ret = -ENOKEY;
-- 
2.17.1