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SUNRPC: Obscure Kerberos integrity keys

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There's no need to keep the integrity keys around if we instead
allocate and key a pair of ahashes and keep those. This not only
enables the subkeys to be destroyed immediately after deriving
them, but it makes the Kerberos integrity code path more efficient.

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 12:21:13 -05:00
parent 2dbe0cac3c
commit 8270dbfceb
3 changed files with 23 additions and 124 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
include/linux/sunrpc/gss_krb5.h
View File

@ -104,14 +104,14 @@ struct krb5_ctx {
struct crypto_sync_skcipher *initiator_enc_aux;
struct crypto_ahash *acceptor_sign;
struct crypto_ahash *initiator_sign;
struct crypto_ahash *initiator_integ;
struct crypto_ahash *acceptor_integ;
u8 Ksess[GSS_KRB5_MAX_KEYLEN]; /* session key */
u8 cksum[GSS_KRB5_MAX_KEYLEN];
atomic_t seq_send;
atomic64_t seq_send64;
time64_t endtime;
struct xdr_netobj mech_used;
u8 initiator_integ[GSS_KRB5_MAX_KEYLEN];
u8 acceptor_integ[GSS_KRB5_MAX_KEYLEN];
};
/* The length of the Kerberos GSS token header */
@ -233,11 +233,6 @@ make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,
struct xdr_buf *body, int body_offset, u8 *cksumkey,
unsigned int usage, struct xdr_netobj *cksumout);
u32
make_checksum_v2(struct krb5_ctx *, char *header, int hdrlen,
struct xdr_buf *body, int body_offset, u8 *key,
unsigned int usage, struct xdr_netobj *cksum);
u32 gss_get_mic_kerberos(struct gss_ctx *, struct xdr_buf *,
struct xdr_netobj *);

116
net/sunrpc/auth_gss/gss_krb5_crypto.c
View File

@ -259,93 +259,6 @@ out_free_cksum:
return err ? GSS_S_FAILURE : 0;
}
/*
* checksum the plaintext data and hdrlen bytes of the token header
* Per rfc4121, sec. 4.2.4, the checksum is performed over the data
* body then over the first 16 octets of the MIC token
* Inclusion of the header data in the calculation of the
* checksum is optional.
*/
u32
make_checksum_v2(struct krb5_ctx *kctx, char *header, int hdrlen,
struct xdr_buf *body, int body_offset, u8 *cksumkey,
unsigned int usage, struct xdr_netobj *cksumout)
{
struct crypto_ahash *tfm;
struct ahash_request *req;
struct scatterlist sg[1];
int err = -1;
u8 *checksumdata;
if (kctx->gk5e->keyed_cksum == 0) {
dprintk("%s: expected keyed hash for %s\n",
__func__, kctx->gk5e->name);
return GSS_S_FAILURE;
}
if (cksumkey == NULL) {
dprintk("%s: no key supplied for %s\n",
__func__, kctx->gk5e->name);
return GSS_S_FAILURE;
}
checksumdata = kmalloc(GSS_KRB5_MAX_CKSUM_LEN, GFP_KERNEL);
if (!checksumdata)
return GSS_S_FAILURE;
tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(tfm))
goto out_free_cksum;
req = ahash_request_alloc(tfm, GFP_KERNEL);
if (!req)
goto out_free_ahash;
ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
err = crypto_ahash_setkey(tfm, cksumkey, kctx->gk5e->keylength);
if (err)
goto out;
err = crypto_ahash_init(req);
if (err)
goto out;
err = xdr_process_buf(body, body_offset, body->len - body_offset,
checksummer, req);
if (err)
goto out;
if (header != NULL) {
sg_init_one(sg, header, hdrlen);
ahash_request_set_crypt(req, sg, NULL, hdrlen);
err = crypto_ahash_update(req);
if (err)
goto out;
}
ahash_request_set_crypt(req, NULL, checksumdata, 0);
err = crypto_ahash_final(req);
if (err)
goto out;
cksumout->len = kctx->gk5e->cksumlength;
switch (kctx->gk5e->ctype) {
case CKSUMTYPE_HMAC_SHA1_96_AES128:
case CKSUMTYPE_HMAC_SHA1_96_AES256:
/* note that this truncates the hash */
memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
break;
default:
BUG();
break;
}
out:
ahash_request_free(req);
out_free_ahash:
crypto_free_ahash(tfm);
out_free_cksum:
kfree(checksumdata);
return err ? GSS_S_FAILURE : 0;
}
/**
* gss_krb5_checksum - Compute the MAC for a GSS Wrap or MIC token
* @tfm: an initialized hash transform
@ -702,27 +615,24 @@ gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset,
{
u32 err;
struct xdr_netobj hmac;
u8 *cksumkey;
u8 *ecptr;
struct crypto_sync_skcipher *cipher, *aux_cipher;
struct crypto_ahash *ahash;
int blocksize;
struct page **save_pages;
int nblocks, nbytes;
struct encryptor_desc desc;
u32 cbcbytes;
unsigned int usage;
unsigned int conflen;
if (kctx->initiate) {
cipher = kctx->initiator_enc;
aux_cipher = kctx->initiator_enc_aux;
cksumkey = kctx->initiator_integ;
usage = KG_USAGE_INITIATOR_SEAL;
ahash = kctx->initiator_integ;
} else {
cipher = kctx->acceptor_enc;
aux_cipher = kctx->acceptor_enc_aux;
cksumkey = kctx->acceptor_integ;
usage = KG_USAGE_ACCEPTOR_SEAL;
ahash = kctx->acceptor_integ;
}
blocksize = crypto_sync_skcipher_blocksize(cipher);
conflen = crypto_sync_skcipher_blocksize(cipher);
@ -762,9 +672,8 @@ gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset,
save_pages = buf->pages;
buf->pages = pages;
err = make_checksum_v2(kctx, NULL, 0, buf,
offset + GSS_KRB5_TOK_HDR_LEN,
cksumkey, usage, &hmac);
err = gss_krb5_checksum(ahash, NULL, 0, buf,
offset + GSS_KRB5_TOK_HDR_LEN, &hmac);
buf->pages = save_pages;
if (err)
return GSS_S_FAILURE;
@ -825,25 +734,22 @@ gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
{
struct xdr_buf subbuf;
u32 ret = 0;
u8 *cksum_key;
struct crypto_sync_skcipher *cipher, *aux_cipher;
struct crypto_ahash *ahash;
struct xdr_netobj our_hmac_obj;
u8 our_hmac[GSS_KRB5_MAX_CKSUM_LEN];
u8 pkt_hmac[GSS_KRB5_MAX_CKSUM_LEN];
int nblocks, blocksize, cbcbytes;
struct decryptor_desc desc;
unsigned int usage;
if (kctx->initiate) {
cipher = kctx->acceptor_enc;
aux_cipher = kctx->acceptor_enc_aux;
cksum_key = kctx->acceptor_integ;
usage = KG_USAGE_ACCEPTOR_SEAL;
ahash = kctx->acceptor_integ;
} else {
cipher = kctx->initiator_enc;
aux_cipher = kctx->initiator_enc_aux;
cksum_key = kctx->initiator_integ;
usage = KG_USAGE_INITIATOR_SEAL;
ahash = kctx->initiator_integ;
}
blocksize = crypto_sync_skcipher_blocksize(cipher);
@ -883,13 +789,9 @@ gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
if (ret)
goto out_err;
/* Calculate our hmac over the plaintext data */
our_hmac_obj.len = sizeof(our_hmac);
our_hmac_obj.data = our_hmac;
ret = make_checksum_v2(kctx, NULL, 0, &subbuf, 0,
cksum_key, usage, &our_hmac_obj);
ret = gss_krb5_checksum(ahash, NULL, 0, &subbuf, 0, &our_hmac_obj);
if (ret)
goto out_err;

22
net/sunrpc/auth_gss/gss_krb5_mech.c
View File

@ -447,23 +447,21 @@ context_derive_keys_new(struct krb5_ctx *ctx, gfp_t gfp_mask)
/* initiator seal integrity */
set_cdata(cdata, KG_USAGE_INITIATOR_SEAL, KEY_USAGE_SEED_INTEGRITY);
keyout.data = ctx->initiator_integ;
err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
if (err) {
dprintk("%s: Error %d deriving initiator_integ key\n",
__func__, err);
if (err)
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);
keyout.data = ctx->acceptor_integ;
err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask);
if (err) {
dprintk("%s: Error %d deriving acceptor_integ key\n",
__func__, err);
if (err)
goto out_free;
ctx->acceptor_integ = gss_krb5_alloc_hash_v2(ctx, &keyout);
if (ctx->acceptor_integ == NULL)
goto out_free;
}
ret = 0;
out:
@ -471,6 +469,8 @@ out:
return ret;
out_free:
crypto_free_ahash(ctx->acceptor_integ);
crypto_free_ahash(ctx->initiator_integ);
crypto_free_ahash(ctx->acceptor_sign);
crypto_free_ahash(ctx->initiator_sign);
crypto_free_sync_skcipher(ctx->acceptor_enc_aux);
@ -598,6 +598,8 @@ gss_delete_sec_context_kerberos(void *internal_ctx) {
crypto_free_sync_skcipher(kctx->initiator_enc_aux);
crypto_free_ahash(kctx->acceptor_sign);
crypto_free_ahash(kctx->initiator_sign);
crypto_free_ahash(kctx->acceptor_integ);
crypto_free_ahash(kctx->initiator_integ);
kfree(kctx->mech_used.data);
kfree(kctx);
}