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

From: Ard Biesheuvel
Date: Fri Dec 18 2020 - 12:04:03 EST


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 <ardb@xxxxxxxxxx>
---
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