diff options
| -rw-r--r-- | net/sunrpc/auth_gss/gss_krb5_internal.h | 6 | ||||
| -rw-r--r-- | net/sunrpc/auth_gss/gss_krb5_keys.c | 117 | ||||
| -rw-r--r-- | net/sunrpc/auth_gss/gss_krb5_mech.c | 2 |
3 files changed, 125 insertions, 0 deletions
diff --git a/net/sunrpc/auth_gss/gss_krb5_internal.h b/net/sunrpc/auth_gss/gss_krb5_internal.h index c7580026adc7..33abf9ee9508 100644 --- a/net/sunrpc/auth_gss/gss_krb5_internal.h +++ b/net/sunrpc/auth_gss/gss_krb5_internal.h @@ -52,6 +52,12 @@ int krb5_derive_key_v2(const struct gss_krb5_enctype *gk5e, const struct xdr_netobj *label, gfp_t gfp_mask); +int krb5_kdf_hmac_sha2(const struct gss_krb5_enctype *gk5e, + const struct xdr_netobj *inkey, + struct xdr_netobj *outkey, + const struct xdr_netobj *in_constant, + gfp_t gfp_mask); + /** * krb5_derive_key - Derive a subkey from a protocol key * @kctx: Kerberos 5 context diff --git a/net/sunrpc/auth_gss/gss_krb5_keys.c b/net/sunrpc/auth_gss/gss_krb5_keys.c index f6de4fdd63ae..724be20f5417 100644 --- a/net/sunrpc/auth_gss/gss_krb5_keys.c +++ b/net/sunrpc/auth_gss/gss_krb5_keys.c @@ -60,6 +60,7 @@ #include <linux/sunrpc/gss_krb5.h> #include <linux/sunrpc/xdr.h> #include <linux/lcm.h> +#include <crypto/hash.h> #include "gss_krb5_internal.h" @@ -361,3 +362,119 @@ int krb5_derive_key_v2(const struct gss_krb5_enctype *gk5e, kfree_sensitive(inblock.data); return ret; } + +/* + * K1 = HMAC-SHA(key, 0x00000001 | label | 0x00 | k) + * + * key: The source of entropy from which subsequent keys are derived. + * + * label: An octet string describing the intended usage of the + * derived key. + * + * k: Length in bits of the key to be outputted, expressed in + * big-endian binary representation in 4 bytes. + */ +static int +krb5_hmac_K1(struct crypto_shash *tfm, const struct xdr_netobj *label, + u32 outlen, struct xdr_netobj *K1) +{ + __be32 k = cpu_to_be32(outlen * 8); + SHASH_DESC_ON_STACK(desc, tfm); + __be32 one = cpu_to_be32(1); + u8 zero = 0; + int ret; + + desc->tfm = tfm; + ret = crypto_shash_init(desc); + if (ret) + goto out_err; + ret = crypto_shash_update(desc, (u8 *)&one, sizeof(one)); + if (ret) + goto out_err; + ret = crypto_shash_update(desc, label->data, label->len); + if (ret) + goto out_err; + ret = crypto_shash_update(desc, &zero, sizeof(zero)); + if (ret) + goto out_err; + ret = crypto_shash_update(desc, (u8 *)&k, sizeof(k)); + if (ret) + goto out_err; + ret = crypto_shash_final(desc, K1->data); + if (ret) + goto out_err; + +out_err: + shash_desc_zero(desc); + return ret; +} + +/** + * krb5_kdf_hmac_sha2 - Derive a subkey for an AES/SHA2-based enctype + * @gk5e: Kerberos 5 enctype policy parameters + * @inkey: base protocol key + * @outkey: OUT: derived key + * @label: subkey usage label + * @gfp_mask: memory allocation control flags + * + * RFC 8009 Section 3: + * + * "We use a key derivation function from Section 5.1 of [SP800-108], + * which uses the HMAC algorithm as the PRF." + * + * function KDF-HMAC-SHA2(key, label, [context,] k): + * k-truncate(K1) + * + * Caller sets @outkey->len to the desired length of the derived key. + * + * On success, returns 0 and fills in @outkey. A negative errno value + * is returned on failure. + */ +int +krb5_kdf_hmac_sha2(const struct gss_krb5_enctype *gk5e, + const struct xdr_netobj *inkey, + struct xdr_netobj *outkey, + const struct xdr_netobj *label, + gfp_t gfp_mask) +{ + struct crypto_shash *tfm; + struct xdr_netobj K1 = { + .data = NULL, + }; + int ret; + + /* + * This implementation assumes the HMAC used for an enctype's + * key derivation is the same as the HMAC used for its + * checksumming. This happens to be true for enctypes that + * are currently supported by this implementation. + */ + tfm = crypto_alloc_shash(gk5e->cksum_name, 0, 0); + if (IS_ERR(tfm)) { + ret = PTR_ERR(tfm); + goto out; + } + ret = crypto_shash_setkey(tfm, inkey->data, inkey->len); + if (ret) + goto out_free_tfm; + + K1.len = crypto_shash_digestsize(tfm); + K1.data = kmalloc(K1.len, gfp_mask); + if (!K1.data) { + ret = -ENOMEM; + goto out_free_tfm; + } + + ret = krb5_hmac_K1(tfm, label, outkey->len, &K1); + if (ret) + goto out_free_tfm; + + /* k-truncate and random-to-key */ + memcpy(outkey->data, K1.data, outkey->len); + +out_free_tfm: + kfree_sensitive(K1.data); + crypto_free_shash(tfm); +out: + return ret; +} diff --git a/net/sunrpc/auth_gss/gss_krb5_mech.c b/net/sunrpc/auth_gss/gss_krb5_mech.c index 1951867f3fa8..b55897cac459 100644 --- a/net/sunrpc/auth_gss/gss_krb5_mech.c +++ b/net/sunrpc/auth_gss/gss_krb5_mech.c @@ -166,6 +166,7 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = { .Ki_length = BITS2OCTETS(128), .import_ctx = gss_krb5_import_ctx_v2, + .derive_key = krb5_kdf_hmac_sha2, .get_mic = gss_krb5_get_mic_v2, .verify_mic = gss_krb5_verify_mic_v2, @@ -190,6 +191,7 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = { .Ki_length = BITS2OCTETS(192), .import_ctx = gss_krb5_import_ctx_v2, + .derive_key = krb5_kdf_hmac_sha2, .get_mic = gss_krb5_get_mic_v2, .verify_mic = gss_krb5_verify_mic_v2, |