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SUNRPC: Hoist KDF into struct gss_krb5_enctype

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Each Kerberos enctype can have a different KDF. Refactor the key
derivation path to support different KDFs for the enctypes
introduced in subsequent patches.

In particular, expose the key derivation function in struct
gss_krb5_enctype instead of the enctype's preferred random-to-key
function. The latter is usually the identity function and is only
ever called during key derivation, so have each KDF call it
directly.

A couple of extra clean-ups:
- Deduplicate the set_cdata() helper
- Have ->derive_key return negative errnos, in accordance with usual
  kernel coding conventions

This patch is a little bigger than I'd like, but these are all
mechanical changes and they are all to the same areas of code. No
behavior change is intended.

Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever
2023-01-15 12:22:11 -05:00
parent ae6ad5d0b7
commit 2691a27d9b
4 changed files with 157 additions and 123 deletions
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25
include/linux/sunrpc/gss_krb5.h
View File

@@ -70,9 +70,11 @@ struct gss_krb5_enctype {
const u32 keybytes; /* raw key len, in bytes */
const u32 keylength; /* final key len, in bytes */
int (*import_ctx)(struct krb5_ctx *ctx, gfp_t gfp_mask);
u32 (*mk_key) (const struct gss_krb5_enctype *gk5e,
struct xdr_netobj *in,
struct xdr_netobj *out); /* complete key generation */
int (*derive_key)(const struct gss_krb5_enctype *gk5e,
const struct xdr_netobj *in,
struct xdr_netobj *out,
const struct xdr_netobj *label,
gfp_t gfp_mask);
u32 (*encrypt)(struct krb5_ctx *kctx, u32 offset,
struct xdr_buf *buf, struct page **pages);
u32 (*decrypt)(struct krb5_ctx *kctx, u32 offset, u32 len,
@@ -257,21 +259,4 @@ krb5_get_seq_num(struct krb5_ctx *kctx,
int
xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen);
u32
krb5_derive_key(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);
u32
gss_krb5_des3_make_key(const struct gss_krb5_enctype *gk5e,
struct xdr_netobj *randombits,
struct xdr_netobj *key);
u32
gss_krb5_aes_make_key(const struct gss_krb5_enctype *gk5e,
struct xdr_netobj *randombits,
struct xdr_netobj *key);
#endif /* _LINUX_SUNRPC_GSS_KRB5_H */

46
net/sunrpc/auth_gss/gss_krb5_internal.h
View File

@@ -38,6 +38,52 @@ u32 gss_krb5_unwrap_v2(struct krb5_ctx *kctx, int offset, int len,
* Implementation internal functions
*/
/* Key Derivation Functions */
int krb5_derive_key_v1(const struct gss_krb5_enctype *gk5e,
const struct xdr_netobj *inkey,
struct xdr_netobj *outkey,
const struct xdr_netobj *label,
gfp_t gfp_mask);
int krb5_derive_key_v2(const struct gss_krb5_enctype *gk5e,
const struct xdr_netobj *inkey,
struct xdr_netobj *outkey,
const struct xdr_netobj *label,
gfp_t gfp_mask);
/**
* krb5_derive_key - Derive a subkey from a protocol key
* @kctx: Kerberos 5 context
* @inkey: base protocol key
* @outkey: OUT: derived key
* @usage: key usage value
* @seed: key usage seed (one octet)
* @gfp_mask: memory allocation control flags
*
* 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.
*/
static inline int krb5_derive_key(struct krb5_ctx *kctx,
const struct xdr_netobj *inkey,
struct xdr_netobj *outkey,
u32 usage, u8 seed, gfp_t gfp_mask)
{
const struct gss_krb5_enctype *gk5e = kctx->gk5e;
u8 label_data[GSS_KRB5_K5CLENGTH];
struct xdr_netobj label = {
.len = sizeof(label_data),
.data = label_data,
};
__be32 *p = (__be32 *)label_data;
*p = cpu_to_be32(usage);
label_data[4] = seed;
return gk5e->derive_key(gk5e, inkey, outkey, &label, gfp_mask);
}
void krb5_make_confounder(u8 *p, int conflen);
u32 gss_krb5_checksum(struct crypto_ahash *tfm, char *header, int hdrlen,

133
net/sunrpc/auth_gss/gss_krb5_keys.c
View File

@@ -139,23 +139,20 @@ static void krb5_nfold(u32 inbits, const u8 *in,
* This is the DK (derive_key) function as described in rfc3961, sec 5.1
* Taken from MIT Kerberos and modified.
*/
u32 krb5_derive_key(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)
static int krb5_DK(const struct gss_krb5_enctype *gk5e,
const struct xdr_netobj *inkey, u8 *rawkey,
const struct xdr_netobj *in_constant, gfp_t gfp_mask)
{
size_t blocksize, keybytes, keylength, n;
unsigned char *inblockdata, *outblockdata, *rawkey;
unsigned char *inblockdata, *outblockdata;
struct xdr_netobj inblock, outblock;
struct crypto_sync_skcipher *cipher;
u32 ret = EINVAL;
int ret = -EINVAL;
keybytes = gk5e->keybytes;
keylength = gk5e->keylength;
if ((inkey->len != keylength) || (outkey->len != keylength))
if (inkey->len != keylength)
goto err_return;
cipher = crypto_alloc_sync_skcipher(gk5e->encrypt_name, 0, 0);
@@ -165,7 +162,7 @@ u32 krb5_derive_key(const struct gss_krb5_enctype *gk5e,
if (crypto_sync_skcipher_setkey(cipher, inkey->data, inkey->len))
goto err_return;
ret = ENOMEM;
ret = -ENOMEM;
inblockdata = kmalloc(blocksize, gfp_mask);
if (inblockdata == NULL)
goto err_free_cipher;
@@ -174,10 +171,6 @@ u32 krb5_derive_key(const struct gss_krb5_enctype *gk5e,
if (outblockdata == NULL)
goto err_free_in;
rawkey = kmalloc(keybytes, gfp_mask);
if (rawkey == NULL)
goto err_free_out;
inblock.data = (char *) inblockdata;
inblock.len = blocksize;
@@ -210,26 +203,8 @@ u32 krb5_derive_key(const struct gss_krb5_enctype *gk5e,
n += outblock.len;
}
/* postprocess the key */
inblock.data = (char *) rawkey;
inblock.len = keybytes;
BUG_ON(gk5e->mk_key == NULL);
ret = (*(gk5e->mk_key))(gk5e, &inblock, outkey);
if (ret) {
dprintk("%s: got %d from mk_key function for '%s'\n",
__func__, ret, gk5e->encrypt_name);
goto err_free_raw;
}
/* clean memory, free resources and exit */
ret = 0;
err_free_raw:
kfree_sensitive(rawkey);
err_free_out:
kfree_sensitive(outblockdata);
err_free_in:
kfree_sensitive(inblockdata);
@@ -252,15 +227,11 @@ static void mit_des_fixup_key_parity(u8 key[8])
}
}
/*
* This is the des3 key derivation postprocess function
*/
u32 gss_krb5_des3_make_key(const struct gss_krb5_enctype *gk5e,
struct xdr_netobj *randombits,
struct xdr_netobj *key)
static int krb5_random_to_key_v1(const struct gss_krb5_enctype *gk5e,
struct xdr_netobj *randombits,
struct xdr_netobj *key)
{
int i;
u32 ret = EINVAL;
int i, ret = -EINVAL;
if (key->len != 24) {
dprintk("%s: key->len is %d\n", __func__, key->len);
@@ -292,14 +263,49 @@ u32 gss_krb5_des3_make_key(const struct gss_krb5_enctype *gk5e,
return ret;
}
/*
* This is the aes key derivation postprocess function
/**
* krb5_derive_key_v1 - Derive a subkey for an RFC 3961 enctype
* @gk5e: Kerberos 5 enctype profile
* @inkey: base protocol key
* @outkey: OUT: derived key
* @label: subkey usage label
* @gfp_mask: memory allocation control flags
*
* 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.
*/
u32 gss_krb5_aes_make_key(const struct gss_krb5_enctype *gk5e,
struct xdr_netobj *randombits,
struct xdr_netobj *key)
int krb5_derive_key_v1(const struct gss_krb5_enctype *gk5e,
const struct xdr_netobj *inkey,
struct xdr_netobj *outkey,
const struct xdr_netobj *label,
gfp_t gfp_mask)
{
u32 ret = EINVAL;
struct xdr_netobj inblock;
int ret;
inblock.len = gk5e->keybytes;
inblock.data = kmalloc(inblock.len, gfp_mask);
if (!inblock.data)
return -ENOMEM;
ret = krb5_DK(gk5e, inkey, inblock.data, label, gfp_mask);
if (!ret)
ret = krb5_random_to_key_v1(gk5e, &inblock, outkey);
kfree_sensitive(inblock.data);
return ret;
}
/*
* This is the identity function, with some sanity checking.
*/
static int krb5_random_to_key_v2(const struct gss_krb5_enctype *gk5e,
struct xdr_netobj *randombits,
struct xdr_netobj *key)
{
int ret = -EINVAL;
if (key->len != 16 && key->len != 32) {
dprintk("%s: key->len is %d\n", __func__, key->len);
@@ -320,3 +326,38 @@ u32 gss_krb5_aes_make_key(const struct gss_krb5_enctype *gk5e,
err_out:
return ret;
}
/**
* krb5_derive_key_v2 - Derive a subkey for an RFC 3962 enctype
* @gk5e: Kerberos 5 enctype profile
* @inkey: base protocol key
* @outkey: OUT: derived key
* @label: subkey usage label
* @gfp_mask: memory allocation control flags
*
* 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_derive_key_v2(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 xdr_netobj inblock;
int ret;
inblock.len = gk5e->keybytes;
inblock.data = kmalloc(inblock.len, gfp_mask);
if (!inblock.data)
return -ENOMEM;
ret = krb5_DK(gk5e, inkey, inblock.data, label, gfp_mask);
if (!ret)
ret = krb5_random_to_key_v2(gk5e, &inblock, outkey);
kfree_sensitive(inblock.data);
return ret;
}

76
net/sunrpc/auth_gss/gss_krb5_mech.c
View File

@@ -49,7 +49,6 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
.encrypt_name = "cbc(des)",
.cksum_name = "md5",
.import_ctx = gss_krb5_import_ctx_des,
.mk_key = NULL,
.get_mic = gss_krb5_get_mic_v1,
.verify_mic = gss_krb5_verify_mic_v1,
.wrap = gss_krb5_wrap_v1,
@@ -71,7 +70,7 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
.encrypt_name = "cbc(des3_ede)",
.cksum_name = "hmac(sha1)",
.import_ctx = gss_krb5_import_ctx_v1,
.mk_key = gss_krb5_des3_make_key,
.derive_key = krb5_derive_key_v1,
.get_mic = gss_krb5_get_mic_v1,
.verify_mic = gss_krb5_verify_mic_v1,
.wrap = gss_krb5_wrap_v1,
@@ -97,7 +96,7 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
.aux_cipher = "cbc(aes)",
.cksum_name = "hmac(sha1)",
.import_ctx = gss_krb5_import_ctx_v2,
.mk_key = gss_krb5_aes_make_key,
.derive_key = krb5_derive_key_v2,
.encrypt = gss_krb5_aes_encrypt,
.decrypt = gss_krb5_aes_decrypt,
@@ -124,7 +123,7 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
.aux_cipher = "cbc(aes)",
.cksum_name = "hmac(sha1)",
.import_ctx = gss_krb5_import_ctx_v2,
.mk_key = gss_krb5_aes_make_key,
.derive_key = krb5_derive_key_v2,
.encrypt = gss_krb5_aes_encrypt,
.decrypt = gss_krb5_aes_decrypt,
@@ -358,16 +357,6 @@ context_v2_alloc_cipher(struct krb5_ctx *ctx, const char *cname, u8 *key)
return cp;
}
static inline void
set_cdata(u8 cdata[GSS_KRB5_K5CLENGTH], u32 usage, u8 seed)
{
cdata[0] = (usage>>24)&0xff;
cdata[1] = (usage>>16)&0xff;
cdata[2] = (usage>>8)&0xff;
cdata[3] = usage&0xff;
cdata[4] = seed;
}
#if defined(CONFIG_RPCSEC_GSS_KRB5_SIMPLIFIED)
static int
gss_krb5_import_ctx_des(struct krb5_ctx *ctx, gfp_t gfp_mask)
@@ -378,16 +367,10 @@ gss_krb5_import_ctx_des(struct krb5_ctx *ctx, gfp_t gfp_mask)
static int
gss_krb5_import_ctx_v1(struct krb5_ctx *ctx, gfp_t gfp_mask)
{
struct xdr_netobj c, keyin, keyout;
u8 cdata[GSS_KRB5_K5CLENGTH];
u32 err;
c.len = GSS_KRB5_K5CLENGTH;
c.data = cdata;
struct xdr_netobj keyin, keyout;
keyin.data = ctx->Ksess;
keyin.len = ctx->gk5e->keylength;
keyout.len = ctx->gk5e->keylength;
/* seq uses the raw key */
ctx->seq = context_v2_alloc_cipher(ctx, ctx->gk5e->encrypt_name,
@@ -401,14 +384,11 @@ gss_krb5_import_ctx_v1(struct krb5_ctx *ctx, gfp_t gfp_mask)
goto out_free_seq;
/* derive cksum */
set_cdata(cdata, KG_USAGE_SIGN, KEY_USAGE_SEED_CHECKSUM);
keyout.data = ctx->cksum;
err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
if (err) {
dprintk("%s: Error %d deriving cksum key\n",
__func__, err);
keyout.len = ctx->gk5e->keylength;
if (krb5_derive_key(ctx, &keyin, &keyout, KG_USAGE_SIGN,
KEY_USAGE_SEED_CHECKSUM, gfp_mask))
goto out_free_enc;
}
return 0;
@@ -441,11 +421,6 @@ gss_krb5_alloc_hash_v2(struct krb5_ctx *kctx, const struct xdr_netobj *key)
static int
gss_krb5_import_ctx_v2(struct krb5_ctx *ctx, gfp_t gfp_mask)
{
u8 cdata[GSS_KRB5_K5CLENGTH];
struct xdr_netobj c = {
.len = sizeof(cdata),
.data = cdata,
};
struct xdr_netobj keyin = {
.len = ctx->gk5e->keylength,
.data = ctx->Ksess,
@@ -453,7 +428,6 @@ gss_krb5_import_ctx_v2(struct krb5_ctx *ctx, gfp_t gfp_mask)
struct xdr_netobj keyout;
int ret = -EINVAL;
void *subkey;
u32 err;
subkey = kmalloc(ctx->gk5e->keylength, gfp_mask);
if (!subkey)
@@ -462,13 +436,9 @@ gss_krb5_import_ctx_v2(struct krb5_ctx *ctx, gfp_t gfp_mask)
keyout.data = subkey;
/* initiator seal encryption */
set_cdata(cdata, KG_USAGE_INITIATOR_SEAL, KEY_USAGE_SEED_ENCRYPTION);
err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
if (err) {
dprintk("%s: Error %d deriving initiator_seal key\n",
__func__, err);
if (krb5_derive_key(ctx, &keyin, &keyout, KG_USAGE_INITIATOR_SEAL,
KEY_USAGE_SEED_ENCRYPTION, gfp_mask))
goto out;
}
ctx->initiator_enc = context_v2_alloc_cipher(ctx,
ctx->gk5e->encrypt_name,
subkey);
@@ -483,13 +453,9 @@ gss_krb5_import_ctx_v2(struct krb5_ctx *ctx, gfp_t gfp_mask)
}
/* acceptor seal encryption */
set_cdata(cdata, KG_USAGE_ACCEPTOR_SEAL, KEY_USAGE_SEED_ENCRYPTION);
err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
if (err) {
dprintk("%s: Error %d deriving acceptor_seal key\n",
__func__, err);
if (krb5_derive_key(ctx, &keyin, &keyout, KG_USAGE_ACCEPTOR_SEAL,
KEY_USAGE_SEED_ENCRYPTION, gfp_mask))
goto out_free;
}
ctx->acceptor_enc = context_v2_alloc_cipher(ctx,
ctx->gk5e->encrypt_name,
subkey);
@@ -504,36 +470,32 @@ gss_krb5_import_ctx_v2(struct krb5_ctx *ctx, gfp_t gfp_mask)
}
/* initiator sign checksum */
set_cdata(cdata, KG_USAGE_INITIATOR_SIGN, KEY_USAGE_SEED_CHECKSUM);
err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
if (err)
if (krb5_derive_key(ctx, &keyin, &keyout, KG_USAGE_INITIATOR_SIGN,
KEY_USAGE_SEED_CHECKSUM, gfp_mask))
goto out_free;
ctx->initiator_sign = gss_krb5_alloc_hash_v2(ctx, &keyout);
if (ctx->initiator_sign == NULL)
goto out_free;
/* acceptor sign checksum */
set_cdata(cdata, KG_USAGE_ACCEPTOR_SIGN, KEY_USAGE_SEED_CHECKSUM);
err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
if (err)
if (krb5_derive_key(ctx, &keyin, &keyout, KG_USAGE_ACCEPTOR_SIGN,
KEY_USAGE_SEED_CHECKSUM, gfp_mask))
goto out_free;
ctx->acceptor_sign = gss_krb5_alloc_hash_v2(ctx, &keyout);
if (ctx->acceptor_sign == NULL)
goto out_free;
/* initiator seal integrity */
set_cdata(cdata, KG_USAGE_INITIATOR_SEAL, KEY_USAGE_SEED_INTEGRITY);
err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
if (err)
if (krb5_derive_key(ctx, &keyin, &keyout, KG_USAGE_INITIATOR_SEAL,
KEY_USAGE_SEED_INTEGRITY, gfp_mask))
goto out_free;
ctx->initiator_integ = gss_krb5_alloc_hash_v2(ctx, &keyout);
if (ctx->initiator_integ == NULL)
goto out_free;
/* acceptor seal integrity */
set_cdata(cdata, KG_USAGE_ACCEPTOR_SEAL, KEY_USAGE_SEED_INTEGRITY);
err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
if (err)
if (krb5_derive_key(ctx, &keyin, &keyout, KG_USAGE_ACCEPTOR_SEAL,
KEY_USAGE_SEED_INTEGRITY, gfp_mask))
goto out_free;
ctx->acceptor_integ = gss_krb5_alloc_hash_v2(ctx, &keyout);
if (ctx->acceptor_integ == NULL)