LXR linux/net/sunrpc/auth_gss/gss_krb5

   1/*
   2 * COPYRIGHT (c) 2008
   3 * The Regents of the University of Michigan
   4 * ALL RIGHTS RESERVED
   5 *
   6 * Permission is granted to use, copy, create derivative works
   7 * and redistribute this software and such derivative works
   8 * for any purpose, so long as the name of The University of
   9 * Michigan is not used in any advertising or publicity
  10 * pertaining to the use of distribution of this software
  11 * without specific, written prior authorization.  If the
  12 * above copyright notice or any other identification of the
  13 * University of Michigan is included in any copy of any
  14 * portion of this software, then the disclaimer below must
  15 * also be included.
  16 *
  17 * THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION
  18 * FROM THE UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY
  19 * PURPOSE, AND WITHOUT WARRANTY BY THE UNIVERSITY OF
  20 * MICHIGAN OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING
  21 * WITHOUT LIMITATION THE IMPLIED WARRANTIES OF
  22 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
  23 * REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE LIABLE
  24 * FOR ANY DAMAGES, INCLUDING SPECIAL, INDIRECT, INCIDENTAL, OR
  25 * CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM ARISING
  26 * OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN
  27 * IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF
  28 * SUCH DAMAGES.
  29 */
  30
  31/*
  32 * Copyright (C) 1998 by the FundsXpress, INC.
  33 *
  34 * All rights reserved.
  35 *
  36 * Export of this software from the United States of America may require
  37 * a specific license from the United States Government.  It is the
  38 * responsibility of any person or organization contemplating export to
  39 * obtain such a license before exporting.
  40 *
  41 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
  42 * distribute this software and its documentation for any purpose and
  43 * without fee is hereby granted, provided that the above copyright
  44 * notice appear in all copies and that both that copyright notice and
  45 * this permission notice appear in supporting documentation, and that
  46 * the name of FundsXpress. not be used in advertising or publicity pertaining
  47 * to distribution of the software without specific, written prior
  48 * permission.  FundsXpress makes no representations about the suitability of
  49 * this software for any purpose.  It is provided "as is" without express
  50 * or implied warranty.
  51 *
  52 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  53 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  54 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  55 */
  56
  57#include <crypto/skcipher.h>
  58#include <linux/err.h>
  59#include <linux/types.h>
  60#include <linux/sunrpc/gss_krb5.h>
  61#include <linux/sunrpc/xdr.h>
  62#include <linux/lcm.h>
  63
  64#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  65# define RPCDBG_FACILITY        RPCDBG_AUTH
  66#endif
  67
  68/*
  69 * This is the n-fold function as described in rfc3961, sec 5.1
  70 * Taken from MIT Kerberos and modified.
  71 */
  72
  73static void krb5_nfold(u32 inbits, const u8 *in,
  74                       u32 outbits, u8 *out)
  75{
  76        unsigned long ulcm;
  77        int byte, i, msbit;
  78
  79        /* the code below is more readable if I make these bytes
  80           instead of bits */
  81
  82        inbits >>= 3;
  83        outbits >>= 3;
  84
  85        /* first compute lcm(n,k) */
  86        ulcm = lcm(inbits, outbits);
  87
  88        /* now do the real work */
  89
  90        memset(out, 0, outbits);
  91        byte = 0;
  92
  93        /* this will end up cycling through k lcm(k,n)/k times, which
  94           is correct */
  95        for (i = ulcm-1; i >= 0; i--) {
  96                /* compute the msbit in k which gets added into this byte */
  97                msbit = (
  98                        /* first, start with the msbit in the first,
  99                         * unrotated byte */
 100                         ((inbits << 3) - 1)
 101                         /* then, for each byte, shift to the right
 102                          * for each repetition */
 103                         + (((inbits << 3) + 13) * (i/inbits))
 104                         /* last, pick out the correct byte within
 105                          * that shifted repetition */
 106                         + ((inbits - (i % inbits)) << 3)
 107                         ) % (inbits << 3);
 108
 109                /* pull out the byte value itself */
 110                byte += (((in[((inbits - 1) - (msbit >> 3)) % inbits] << 8)|
 111                                  (in[((inbits) - (msbit >> 3)) % inbits]))
 112                                 >> ((msbit & 7) + 1)) & 0xff;
 113
 114                /* do the addition */
 115                byte += out[i % outbits];
 116                out[i % outbits] = byte & 0xff;
 117
 118                /* keep around the carry bit, if any */
 119                byte >>= 8;
 120
 121        }
 122
 123        /* if there's a carry bit left over, add it back in */
 124        if (byte) {
 125                for (i = outbits - 1; i >= 0; i--) {
 126                        /* do the addition */
 127                        byte += out[i];
 128                        out[i] = byte & 0xff;
 129
 130                        /* keep around the carry bit, if any */
 131                        byte >>= 8;
 132                }
 133        }
 134}
 135
 136/*
 137 * This is the DK (derive_key) function as described in rfc3961, sec 5.1
 138 * Taken from MIT Kerberos and modified.
 139 */
 140
 141u32 krb5_derive_key(const struct gss_krb5_enctype *gk5e,
 142                    const struct xdr_netobj *inkey,
 143                    struct xdr_netobj *outkey,
 144                    const struct xdr_netobj *in_constant,
 145                    gfp_t gfp_mask)
 146{
 147        size_t blocksize, keybytes, keylength, n;
 148        unsigned char *inblockdata, *outblockdata, *rawkey;
 149        struct xdr_netobj inblock, outblock;
 150        struct crypto_skcipher *cipher;
 151        u32 ret = EINVAL;
 152
 153        blocksize = gk5e->blocksize;
 154        keybytes = gk5e->keybytes;
 155        keylength = gk5e->keylength;
 156
 157        if ((inkey->len != keylength) || (outkey->len != keylength))
 158                goto err_return;
 159
 160        cipher = crypto_alloc_skcipher(gk5e->encrypt_name, 0,
 161                                       CRYPTO_ALG_ASYNC);
 162        if (IS_ERR(cipher))
 163                goto err_return;
 164        if (crypto_skcipher_setkey(cipher, inkey->data, inkey->len))
 165                goto err_return;
 166
 167        /* allocate and set up buffers */
 168
 169        ret = ENOMEM;
 170        inblockdata = kmalloc(blocksize, gfp_mask);
 171        if (inblockdata == NULL)
 172                goto err_free_cipher;
 173
 174        outblockdata = kmalloc(blocksize, gfp_mask);
 175        if (outblockdata == NULL)
 176                goto err_free_in;
 177
 178        rawkey = kmalloc(keybytes, gfp_mask);
 179        if (rawkey == NULL)
 180                goto err_free_out;
 181
 182        inblock.data = (char *) inblockdata;
 183        inblock.len = blocksize;
 184
 185        outblock.data = (char *) outblockdata;
 186        outblock.len = blocksize;
 187
 188        /* initialize the input block */
 189
 190        if (in_constant->len == inblock.len) {
 191                memcpy(inblock.data, in_constant->data, inblock.len);
 192        } else {
 193                krb5_nfold(in_constant->len * 8, in_constant->data,
 194                           inblock.len * 8, inblock.data);
 195        }
 196
 197        /* loop encrypting the blocks until enough key bytes are generated */
 198
 199        n = 0;
 200        while (n < keybytes) {
 201                (*(gk5e->encrypt))(cipher, NULL, inblock.data,
 202                                   outblock.data, inblock.len);
 203
 204                if ((keybytes - n) <= outblock.len) {
 205                        memcpy(rawkey + n, outblock.data, (keybytes - n));
 206                        break;
 207                }
 208
 209                memcpy(rawkey + n, outblock.data, outblock.len);
 210                memcpy(inblock.data, outblock.data, outblock.len);
 211                n += outblock.len;
 212        }
 213
 214        /* postprocess the key */
 215
 216        inblock.data = (char *) rawkey;
 217        inblock.len = keybytes;
 218
 219        BUG_ON(gk5e->mk_key == NULL);
 220        ret = (*(gk5e->mk_key))(gk5e, &inblock, outkey);
 221        if (ret) {
 222                dprintk("%s: got %d from mk_key function for '%s'\n",
 223                        __func__, ret, gk5e->encrypt_name);
 224                goto err_free_raw;
 225        }
 226
 227        /* clean memory, free resources and exit */
 228
 229        ret = 0;
 230
 231err_free_raw:
 232        kfree_sensitive(rawkey);
 233err_free_out:
 234        kfree_sensitive(outblockdata);
 235err_free_in:
 236        kfree_sensitive(inblockdata);
 237err_free_cipher:
 238        crypto_free_skcipher(cipher);
 239err_return:
 240        return ret;
 241}
 242
 243#define smask(step) ((1<<step)-1)
 244#define pstep(x, step) (((x)&smask(step))^(((x)>>step)&smask(step)))
 245#define parity_char(x) pstep(pstep(pstep((x), 4), 2), 1)
 246
 247static void mit_des_fixup_key_parity(u8 key[8])
 248{
 249        int i;
 250        for (i = 0; i < 8; i++) {
 251                key[i] &= 0xfe;
 252                key[i] |= 1^parity_char(key[i]);
 253        }
 254}
 255
 256/*
 257 * This is the des3 key derivation postprocess function
 258 */
 259u32 gss_krb5_des3_make_key(const struct gss_krb5_enctype *gk5e,
 260                           struct xdr_netobj *randombits,
 261                           struct xdr_netobj *key)
 262{
 263        int i;
 264        u32 ret = EINVAL;
 265
 266        if (key->len != 24) {
 267                dprintk("%s: key->len is %d\n", __func__, key->len);
 268                goto err_out;
 269        }
 270        if (randombits->len != 21) {
 271                dprintk("%s: randombits->len is %d\n",
 272                        __func__, randombits->len);
 273                goto err_out;
 274        }
 275
 276        /* take the seven bytes, move them around into the top 7 bits of the
 277           8 key bytes, then compute the parity bits.  Do this three times. */
 278
 279        for (i = 0; i < 3; i++) {
 280                memcpy(key->data + i*8, randombits->data + i*7, 7);
 281                key->data[i*8+7] = (((key->data[i*8]&1)<<1) |
 282                                    ((key->data[i*8+1]&1)<<2) |
 283                                    ((key->data[i*8+2]&1)<<3) |
 284                                    ((key->data[i*8+3]&1)<<4) |
 285                                    ((key->data[i*8+4]&1)<<5) |
 286                                    ((key->data[i*8+5]&1)<<6) |
 287                                    ((key->data[i*8+6]&1)<<7));
 288
 289                mit_des_fixup_key_parity(key->data + i*8);
 290        }
 291        ret = 0;
 292err_out:
 293        return ret;
 294}
 295
 296/*
 297 * This is the aes key derivation postprocess function
 298 */
 299u32 gss_krb5_aes_make_key(const struct gss_krb5_enctype *gk5e,
 300                          struct xdr_netobj *randombits,
 301                          struct xdr_netobj *key)
 302{
 303        u32 ret = EINVAL;
 304
 305        if (key->len != 16 && key->len != 32) {
 306                dprintk("%s: key->len is %d\n", __func__, key->len);
 307                goto err_out;
 308        }
 309        if (randombits->len != 16 && randombits->len != 32) {
 310                dprintk("%s: randombits->len is %d\n",
 311                        __func__, randombits->len);
 312                goto err_out;
 313        }
 314        if (randombits->len != key->len) {
 315                dprintk("%s: randombits->len is %d, key->len is %d\n",
 316                        __func__, randombits->len, key->len);
 317                goto err_out;
 318        }
 319        memcpy(key->data, randombits->data, key->len);
 320        ret = 0;
 321err_out:
 322        return ret;
 323}
 324