crypto: hash - annotate algorithms taking optional key
authorEric Biggers <ebiggers@google.com>
Wed, 3 Jan 2018 19:16:26 +0000 (11:16 -0800)
committerBen Hutchings <ben@decadent.org.uk>
Thu, 31 May 2018 23:30:07 +0000 (00:30 +0100)
commit a208fa8f33031b9e0aba44c7d1b7e68eb0cbd29e upstream.

We need to consistently enforce that keyed hashes cannot be used without
setting the key.  To do this we need a reliable way to determine whether
a given hash algorithm is keyed or not.  AF_ALG currently does this by
checking for the presence of a ->setkey() method.  However, this is
actually slightly broken because the CRC-32 algorithms implement
->setkey() but can also be used without a key.  (The CRC-32 "key" is not
actually a cryptographic key but rather represents the initial state.
If not overridden, then a default initial state is used.)

Prepare to fix this by introducing a flag CRYPTO_ALG_OPTIONAL_KEY which
indicates that the algorithm has a ->setkey() method, but it is not
required to be called.  Then set it on all the CRC-32 algorithms.

The same also applies to the Adler-32 implementation in Lustre.

Also, the cryptd and mcryptd templates have to pass through the flag
from their underlying algorithm.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
[bwh: Backported to 3.2:
 - Drop changes to nonexistent drivers
 - There's no CRYPTO_ALG_INTERNAL flag
 - Adjust filenames]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
arch/x86/crypto/crc32c-intel.c
crypto/crc32c.c
crypto/cryptd.c
include/linux/crypto.h

index 7dad700..da4e96b 100644 (file)
@@ -166,6 +166,7 @@ static struct shash_alg alg = {
                .cra_name               =       "crc32c",
                .cra_driver_name        =       "crc32c-intel",
                .cra_priority           =       200,
+               .cra_flags              =       CRYPTO_ALG_OPTIONAL_KEY,
                .cra_blocksize          =       CHKSUM_BLOCK_SIZE,
                .cra_ctxsize            =       sizeof(u32),
                .cra_module             =       THIS_MODULE,
index b2c030b..55f5ed1 100644 (file)
@@ -234,6 +234,7 @@ static struct shash_alg alg = {
                .cra_name               =       "crc32c",
                .cra_driver_name        =       "crc32c-generic",
                .cra_priority           =       100,
+               .cra_flags              =       CRYPTO_ALG_OPTIONAL_KEY,
                .cra_blocksize          =       CHKSUM_BLOCK_SIZE,
                .cra_alignmask          =       3,
                .cra_ctxsize            =       sizeof(struct chksum_ctx),
index 8091e75..3443c11 100644 (file)
@@ -603,7 +603,8 @@ static int cryptd_create_hash(struct crypto_template *tmpl, struct rtattr **tb,
        if (err)
                goto out_free_inst;
 
-       inst->alg.halg.base.cra_flags = CRYPTO_ALG_ASYNC;
+       inst->alg.halg.base.cra_flags = CRYPTO_ALG_ASYNC |
+               (alg->cra_flags & CRYPTO_ALG_OPTIONAL_KEY);
 
        inst->alg.halg.digestsize = salg->digestsize;
        inst->alg.halg.base.cra_ctxsize = sizeof(struct cryptd_hash_ctx);
index 6f501de..b5f3191 100644 (file)
  */
 #define CRYPTO_ALG_INSTANCE            0x00000800
 
+/*
+ * Set if the algorithm has a ->setkey() method but can be used without
+ * calling it first, i.e. there is a default key.
+ */
+#define CRYPTO_ALG_OPTIONAL_KEY                0x00004000
+
 /*
  * Transform masks and values (for crt_flags).
  */