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From:   Ard Biesheuvel <ardb@kernel.org>
To:     linux-crypto@vger.kernel.org
Cc:     linux-arm-kernel@lists.infradead.org,
        Ard Biesheuvel <ardb@kernel.org>,
        Dave Martin <dave.martin@arm.com>,
        Mark Brown <broonie@kernel.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Eric Biggers <ebiggers@kernel.org>,
        Will Deacon <will@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>,
        Andy Lutomirski <luto@kernel.org>
Subject: [PATCH v2 4/9] crypto: aead - disallow en/decrypt for non-task or non-softirq context
Date:   Tue,  2 Mar 2021 10:01:13 +0100
Message-Id: <20210302090118.30666-5-ardb@kernel.org>
In-Reply-To: <20210302090118.30666-1-ardb@kernel.org>
References: <20210302090118.30666-1-ardb@kernel.org>
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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@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;
-- 
2.30.1