KEYS: DH: forbid using digest_null as the KDF hash
Requesting "digest_null" in the keyctl_kdf_params caused an infinite loop in kdf_ctr() because the "null" hash has a digest size of 0. Fix it by rejecting hash algorithms with a digest size of 0. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: James Morris <james.l.morris@oracle.com>
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@ -89,6 +89,7 @@ static int kdf_alloc(struct kdf_sdesc **sdesc_ret, char *hashname)
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struct crypto_shash *tfm;
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struct kdf_sdesc *sdesc;
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int size;
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int err;
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/* allocate synchronous hash */
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tfm = crypto_alloc_shash(hashname, 0, 0);
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@ -97,16 +98,25 @@ static int kdf_alloc(struct kdf_sdesc **sdesc_ret, char *hashname)
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return PTR_ERR(tfm);
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}
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err = -EINVAL;
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if (crypto_shash_digestsize(tfm) == 0)
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goto out_free_tfm;
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err = -ENOMEM;
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size = sizeof(struct shash_desc) + crypto_shash_descsize(tfm);
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sdesc = kmalloc(size, GFP_KERNEL);
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if (!sdesc)
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return -ENOMEM;
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goto out_free_tfm;
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sdesc->shash.tfm = tfm;
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sdesc->shash.flags = 0x0;
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*sdesc_ret = sdesc;
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return 0;
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out_free_tfm:
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crypto_free_shash(tfm);
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return err;
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}
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static void kdf_dealloc(struct kdf_sdesc *sdesc)
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