Re: [PATCH 01/11] keys-encrypted: add nvdimm key format type to encrypted keys

On Tue, 2018-11-27 at 11:10 -0800, Dan Williams wrote: > On Tue, Nov 27, 2018 at 10:24 AM Mimi Zohar <zohar(a)linux.ibm.com&gt; wrote: > > > > On Tue, 2018-11-27 at 09:20 -0700, Dave Jiang wrote: > > > > > > On 11/27/18 12:20 AM, Dan Williams wrote: > > > > On Fri, Nov 9, 2018 at 2:13 PM Dave Jiang <dave.jiang(a)intel.com&gt; 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 <dave.jiang(a)intel.com&gt; > > > >> --- > > > >> 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. > > > > > > > > > > I'm ok with that if Mimi is. > > > > If the usage (eg. format: ecryptfs, nvdimm) limits the dlen size(s), > > how will defining generic key-types help? If there are no usage size > > limitations, then there would be no usage specific definition. > > > > I must be missing something. > > ...or I did a poor job of describing the problem. I'm just looking > ahead to another potential encrypted-key use case, but instead of > nvdimms this would be to lock / unlock persistent memory "namespace" > objects. If it turns out the namespace key is just another 32-byte > encrypted key should the encrypted-keys core grow support for a new > "namespace" key type, should it reuse the "nvdimm" key type, or should > we define a generic 32-byte payload-size-requirement key type? Even with a generic length, there will be format (eg. ecryptfs, nvdimm, namespace) specific code. Otherwise you wouldn't be defining a new format type. switch(dlen) { case enc32: if (ecryptfs) goto fail; ... break; case enc64: if (nvdimm || ns) goto fail; ... break; default: }