crypto: shash - allow essiv and hmac to use OPTIONAL_KEY algorithms
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Message ID 20191129193522.52513-1-ebiggers@kernel.org
State Accepted
Delegated to: Herbert Xu
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Series
  • crypto: shash - allow essiv and hmac to use OPTIONAL_KEY algorithms
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Commit Message

Eric Biggers Nov. 29, 2019, 7:35 p.m. UTC
From: Eric Biggers <ebiggers@google.com>

The essiv and hmac templates refuse to use any hash algorithm that has a
->setkey() function, which includes not just algorithms that always need
a key, but also algorithms that optionally take a key.

Previously the only optionally-keyed hash algorithms in the crypto API
were non-cryptographic algorithms like crc32, so this didn't really
matter.  But that's changed with BLAKE2 support being added.  BLAKE2
should work with essiv and hmac, just like any other cryptographic hash.

Fix this by allowing the use of both algorithms without a ->setkey()
function and algorithms that have the OPTIONAL_KEY flag set.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 crypto/essiv.c                 | 2 +-
 crypto/hmac.c                  | 4 ++--
 crypto/shash.c                 | 3 +--
 include/crypto/internal/hash.h | 6 ++++++
 4 files changed, 10 insertions(+), 5 deletions(-)

Comments

Ard Biesheuvel Dec. 3, 2019, 6:14 p.m. UTC | #1
On Fri, 29 Nov 2019 at 20:36, Eric Biggers <ebiggers@kernel.org> wrote:
>
> From: Eric Biggers <ebiggers@google.com>
>
> The essiv and hmac templates refuse to use any hash algorithm that has a
> ->setkey() function, which includes not just algorithms that always need
> a key, but also algorithms that optionally take a key.
>
> Previously the only optionally-keyed hash algorithms in the crypto API
> were non-cryptographic algorithms like crc32, so this didn't really
> matter.  But that's changed with BLAKE2 support being added.  BLAKE2
> should work with essiv and hmac, just like any other cryptographic hash.
>
> Fix this by allowing the use of both algorithms without a ->setkey()
> function and algorithms that have the OPTIONAL_KEY flag set.
>
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Hey Eric,

Even though I am not convinced that using hmac() with blake2 makes a
lot of sense, I agree that the mere presence or absence of the
setkey() hook should decide whether this is permitted.

So,

Acked-by: Ard Biesheuvel <ardb@kernel.org>

> ---
>  crypto/essiv.c                 | 2 +-
>  crypto/hmac.c                  | 4 ++--
>  crypto/shash.c                 | 3 +--
>  include/crypto/internal/hash.h | 6 ++++++
>  4 files changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/crypto/essiv.c b/crypto/essiv.c
> index 808f2b362106..e4b32c2ea7ec 100644
> --- a/crypto/essiv.c
> +++ b/crypto/essiv.c
> @@ -442,7 +442,7 @@ static bool essiv_supported_algorithms(const char *essiv_cipher_name,
>         if (ivsize != alg->cra_blocksize)
>                 goto out;
>
> -       if (crypto_shash_alg_has_setkey(hash_alg))
> +       if (crypto_shash_alg_needs_key(hash_alg))
>                 goto out;
>
>         ret = true;
> diff --git a/crypto/hmac.c b/crypto/hmac.c
> index 8b2a212eb0ad..377f07733e2f 100644
> --- a/crypto/hmac.c
> +++ b/crypto/hmac.c
> @@ -185,9 +185,9 @@ static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
>                 return PTR_ERR(salg);
>         alg = &salg->base;
>
> -       /* The underlying hash algorithm must be unkeyed */
> +       /* The underlying hash algorithm must not require a key */
>         err = -EINVAL;
> -       if (crypto_shash_alg_has_setkey(salg))
> +       if (crypto_shash_alg_needs_key(salg))
>                 goto out_put_alg;
>
>         ds = salg->digestsize;
> diff --git a/crypto/shash.c b/crypto/shash.c
> index e83c5124f6eb..7989258a46b4 100644
> --- a/crypto/shash.c
> +++ b/crypto/shash.c
> @@ -50,8 +50,7 @@ static int shash_setkey_unaligned(struct crypto_shash *tfm, const u8 *key,
>
>  static void shash_set_needkey(struct crypto_shash *tfm, struct shash_alg *alg)
>  {
> -       if (crypto_shash_alg_has_setkey(alg) &&
> -           !(alg->base.cra_flags & CRYPTO_ALG_OPTIONAL_KEY))
> +       if (crypto_shash_alg_needs_key(alg))
>                 crypto_shash_set_flags(tfm, CRYPTO_TFM_NEED_KEY);
>  }
>
> diff --git a/include/crypto/internal/hash.h b/include/crypto/internal/hash.h
> index bfc9db7b100d..f68dab38f160 100644
> --- a/include/crypto/internal/hash.h
> +++ b/include/crypto/internal/hash.h
> @@ -85,6 +85,12 @@ 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)
> +{
> +       return crypto_shash_alg_has_setkey(alg) &&
> +               !(alg->base.cra_flags & CRYPTO_ALG_OPTIONAL_KEY);
> +}
> +
>  bool crypto_hash_alg_has_setkey(struct hash_alg_common *halg);
>
>  int crypto_init_ahash_spawn(struct crypto_ahash_spawn *spawn,
> --
> 2.24.0
>
Herbert Xu Dec. 11, 2019, 9:42 a.m. UTC | #2
Eric Biggers <ebiggers@kernel.org> wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> The essiv and hmac templates refuse to use any hash algorithm that has a
> ->setkey() function, which includes not just algorithms that always need
> a key, but also algorithms that optionally take a key.
> 
> Previously the only optionally-keyed hash algorithms in the crypto API
> were non-cryptographic algorithms like crc32, so this didn't really
> matter.  But that's changed with BLAKE2 support being added.  BLAKE2
> should work with essiv and hmac, just like any other cryptographic hash.
> 
> Fix this by allowing the use of both algorithms without a ->setkey()
> function and algorithms that have the OPTIONAL_KEY flag set.
> 
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
> crypto/essiv.c                 | 2 +-
> crypto/hmac.c                  | 4 ++--
> crypto/shash.c                 | 3 +--
> include/crypto/internal/hash.h | 6 ++++++
> 4 files changed, 10 insertions(+), 5 deletions(-)

Patch applied.  Thanks.

Patch
diff mbox series

diff --git a/crypto/essiv.c b/crypto/essiv.c
index 808f2b362106..e4b32c2ea7ec 100644
--- a/crypto/essiv.c
+++ b/crypto/essiv.c
@@ -442,7 +442,7 @@  static bool essiv_supported_algorithms(const char *essiv_cipher_name,
 	if (ivsize != alg->cra_blocksize)
 		goto out;
 
-	if (crypto_shash_alg_has_setkey(hash_alg))
+	if (crypto_shash_alg_needs_key(hash_alg))
 		goto out;
 
 	ret = true;
diff --git a/crypto/hmac.c b/crypto/hmac.c
index 8b2a212eb0ad..377f07733e2f 100644
--- a/crypto/hmac.c
+++ b/crypto/hmac.c
@@ -185,9 +185,9 @@  static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
 		return PTR_ERR(salg);
 	alg = &salg->base;
 
-	/* The underlying hash algorithm must be unkeyed */
+	/* The underlying hash algorithm must not require a key */
 	err = -EINVAL;
-	if (crypto_shash_alg_has_setkey(salg))
+	if (crypto_shash_alg_needs_key(salg))
 		goto out_put_alg;
 
 	ds = salg->digestsize;
diff --git a/crypto/shash.c b/crypto/shash.c
index e83c5124f6eb..7989258a46b4 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -50,8 +50,7 @@  static int shash_setkey_unaligned(struct crypto_shash *tfm, const u8 *key,
 
 static void shash_set_needkey(struct crypto_shash *tfm, struct shash_alg *alg)
 {
-	if (crypto_shash_alg_has_setkey(alg) &&
-	    !(alg->base.cra_flags & CRYPTO_ALG_OPTIONAL_KEY))
+	if (crypto_shash_alg_needs_key(alg))
 		crypto_shash_set_flags(tfm, CRYPTO_TFM_NEED_KEY);
 }
 
diff --git a/include/crypto/internal/hash.h b/include/crypto/internal/hash.h
index bfc9db7b100d..f68dab38f160 100644
--- a/include/crypto/internal/hash.h
+++ b/include/crypto/internal/hash.h
@@ -85,6 +85,12 @@  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)
+{
+	return crypto_shash_alg_has_setkey(alg) &&
+		!(alg->base.cra_flags & CRYPTO_ALG_OPTIONAL_KEY);
+}
+
 bool crypto_hash_alg_has_setkey(struct hash_alg_common *halg);
 
 int crypto_init_ahash_spawn(struct crypto_ahash_spawn *spawn,