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From:   Eric Biggers <ebiggers@kernel.org>
To:     linux-crypto@vger.kernel.org
Cc:     x86@kernel.org, linux-arm-kernel@lists.infradead.org,
        Sami Tolvanen <samitolvanen@google.com>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>
Subject: [PATCH v2 12/12] Revert "crypto: shash - avoid comparing pointers to exported functions under CFI"
Date:   Fri, 18 Nov 2022 11:44:21 -0800
Message-Id: <20221118194421.160414-13-ebiggers@kernel.org>
In-Reply-To: <20221118194421.160414-1-ebiggers@kernel.org>
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From: Eric Biggers <ebiggers@google.com>

This reverts commit 22ca9f4aaf431a9413dcc115dd590123307f274f because CFI
no longer breaks cross-module function address equality, so
crypto_shash_alg_has_setkey() can now be an inline function like before.

This commit should not be backported to kernels that don't have the new
CFI implementation.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 crypto/shash.c                 | 18 +++---------------
 include/crypto/internal/hash.h |  8 +++++++-
 2 files changed, 10 insertions(+), 16 deletions(-)

diff --git a/crypto/shash.c b/crypto/shash.c
index 4c88e63b3350f..0f85431588267 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -20,24 +20,12 @@
 
 static const struct crypto_type crypto_shash_type;
 
-static int shash_no_setkey(struct crypto_shash *tfm, const u8 *key,
-			   unsigned int keylen)
+int shash_no_setkey(struct crypto_shash *tfm, const u8 *key,
+		    unsigned int keylen)
 {
 	return -ENOSYS;
 }
-
-/*
- * Check whether an shash algorithm has a setkey function.
- *
- * For CFI compatibility, this must not be an inline function.  This is because
- * when CFI is enabled, modules won't get the same address for shash_no_setkey
- * (if it were exported, which inlining would require) as the core kernel will.
- */
-bool crypto_shash_alg_has_setkey(struct shash_alg *alg)
-{
-	return alg->setkey != shash_no_setkey;
-}
-EXPORT_SYMBOL_GPL(crypto_shash_alg_has_setkey);
+EXPORT_SYMBOL_GPL(shash_no_setkey);
 
 static int shash_setkey_unaligned(struct crypto_shash *tfm, const u8 *key,
 				  unsigned int keylen)
diff --git a/include/crypto/internal/hash.h b/include/crypto/internal/hash.h
index 25806141db591..0a288dddcf5be 100644
--- a/include/crypto/internal/hash.h
+++ b/include/crypto/internal/hash.h
@@ -75,7 +75,13 @@ void crypto_unregister_ahashes(struct ahash_alg *algs, int count);
 int ahash_register_instance(struct crypto_template *tmpl,
 			    struct ahash_instance *inst);
 
-bool crypto_shash_alg_has_setkey(struct shash_alg *alg);
+int shash_no_setkey(struct crypto_shash *tfm, const u8 *key,
+		    unsigned int keylen);
+
+static inline bool crypto_shash_alg_has_setkey(struct shash_alg *alg)
+{
+	return alg->setkey != shash_no_setkey;
+}
 
 static inline bool crypto_shash_alg_needs_key(struct shash_alg *alg)
 {
-- 
2.38.1