On Fri, Nov 9, 2018 at 2:13 PM Dave Jiang <[email protected]> wrote:
>
> Adding nvdimm key format type to encrypted keys in order to limit the size

s/Adding/Add an/

> of the key to 32-bytes.
>
> Signed-off-by: Dave Jiang <[email protected]>
> ---
>  security/keys/encrypted-keys/encrypted.c |   29 ++++++++++++++++++++---------
>  1 file changed, 20 insertions(+), 9 deletions(-)
>
> diff --git a/security/keys/encrypted-keys/encrypted.c 
> b/security/keys/encrypted-keys/encrypted.c
> index d92cbf9687c3..182b4f136bdf 100644
> --- a/security/keys/encrypted-keys/encrypted.c
> +++ b/security/keys/encrypted-keys/encrypted.c
> @@ -45,6 +45,7 @@ static const char hmac_alg[] = "hmac(sha256)";
>  static const char blkcipher_alg[] = "cbc(aes)";
>  static const char key_format_default[] = "default";
>  static const char key_format_ecryptfs[] = "ecryptfs";
> +static const char key_format_nvdimm[] = "nvdimm";
>  static unsigned int ivsize;
>  static int blksize;
>
> @@ -54,6 +55,7 @@ static int blksize;
>  #define HASH_SIZE SHA256_DIGEST_SIZE
>  #define MAX_DATA_SIZE 4096
>  #define MIN_DATA_SIZE  20
> +#define KEY_NVDIMM_PAYLOAD_LEN 32
>
>  static struct crypto_shash *hash_tfm;
>
> @@ -62,12 +64,13 @@ enum {
>  };
>
>  enum {
> -       Opt_error = -1, Opt_default, Opt_ecryptfs
> +       Opt_error = -1, Opt_default, Opt_ecryptfs, Opt_nvdimm
>  };
>
>  static const match_table_t key_format_tokens = {
>         {Opt_default, "default"},
>         {Opt_ecryptfs, "ecryptfs"},
> +       {Opt_nvdimm, "nvdimm"},
>         {Opt_error, NULL}
>  };
>
> @@ -195,6 +198,7 @@ static int datablob_parse(char *datablob, const char 
> **format,
>         key_format = match_token(p, key_format_tokens, args);
>         switch (key_format) {
>         case Opt_ecryptfs:
> +       case Opt_nvdimm:
>         case Opt_default:
>                 *format = p;
>                 *master_desc = strsep(&datablob, " \t");
> @@ -625,15 +629,22 @@ static struct encrypted_key_payload 
> *encrypted_key_alloc(struct key *key,
>         format_len = (!format) ? strlen(key_format_default) : strlen(format);
>         decrypted_datalen = dlen;
>         payload_datalen = decrypted_datalen;
> -       if (format && !strcmp(format, key_format_ecryptfs)) {
> -               if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
> -                       pr_err("encrypted_key: keylen for the ecryptfs format 
> "
> -                              "must be equal to %d bytes\n",
> -                              ECRYPTFS_MAX_KEY_BYTES);
> -                       return ERR_PTR(-EINVAL);
> +       if (format) {
> +               if (!strcmp(format, key_format_ecryptfs)) {
> +                       if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
> +                               pr_err("encrypted_key: keylen for the 
> ecryptfs format must be equal to %d bytes\n",
> +                                       ECRYPTFS_MAX_KEY_BYTES);
> +                               return ERR_PTR(-EINVAL);
> +                       }
> +                       decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
> +                       payload_datalen = sizeof(struct ecryptfs_auth_tok);
> +               } else if (!strcmp(format, key_format_nvdimm)) {
> +                       if (decrypted_datalen != KEY_NVDIMM_PAYLOAD_LEN) {
> +                               pr_err("encrypted_key: nvdimm key payload 
> incorrect length: %d\n",
> +                                               decrypted_datalen);
> +                               return ERR_PTR(-EINVAL);
> +                       }

I suspect this may not be the last key type that gets added, but I
wonder if we should instead create key-types based on the dlen size.
I.e. create a generic 32-byte key-type "enc32"? That way if another
32-byte requirement key comes along we don't need to come touch this
routine again.
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