/*
* linux/net/sunrpc/gss_spkm3_token.c
*
* Copyright (c) 2003 The Regents of the University of Michigan.
* All rights reserved.
*
* Andy Adamson <andros@umich.edu>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/sunrpc/gss_spkm3.h>
#include <linux/random.h>
#include <linux/crypto.h>
#ifdef RPC_DEBUG
# define RPCDBG_FACILITY RPCDBG_AUTH
#endif
/*
* asn1_bitstring_len()
*
* calculate the asn1 bitstring length of the xdr_netobject
*/
void
asn1_bitstring_len(struct xdr_netobj *in, int *enclen, int *zerobits)
{
int i, zbit = 0,elen = in->len;
char *ptr;
ptr = &in->data[in->len -1];
/* count trailing 0's */
for(i = in->len; i > 0; i--) {
if (*ptr == 0) {
ptr--;
elen--;
} else
break;
}
/* count number of 0 bits in final octet */
ptr = &in->data[elen - 1];
for(i = 0; i < 8; i++) {
short mask = 0x01;
if (!((mask << i) & *ptr))
zbit++;
else
break;
}
*enclen = elen;
*zerobits = zbit;
}
/*
* decode_asn1_bitstring()
*
* decode a bitstring into a buffer of the expected length.
* enclen = bit string length
* explen = expected length (define in rfc)
*/
int
decode_asn1_bitstring(struct xdr_netobj *out, char *in, int enclen, int explen)
{
if (!(out->data = kzalloc(explen,GFP_KERNEL)))
return 0;
out->len = explen;
memcpy(out->data, in, enclen);
return 1;
}
/*
* SPKMInnerContextToken choice SPKM_MIC asn1 token layout
*
* contextid is always 16 bytes plain data. max asn1 bitstring len = 17.
*
* tokenlen = pos[0] to end of token (max pos[45] with MD5 cksum)
*
* pos value
* ----------
* [0] a4 SPKM-MIC tag
* [1] ?? innertoken length (max 44)
*
*
* tok_hdr piece of checksum data starts here
*
* the maximum mic-header len = 9 + 17 = 26
* mic-header
* ----------
* [2] 30 SEQUENCE tag
* [3] ?? mic-header length: (max 23) = TokenID + ContextID
*
* TokenID - all fields constant and can be hardcoded
* -------
* [4] 02 Type 2
* [5] 02 Length 2
* [6][7] 01 01 TokenID (SPKM_MIC_TOK)
*
* ContextID - encoded length not constant, calculated
* ---------
* [8] 03 Type 3
* [9] ?? encoded length
* [10] ?? ctxzbit
* [11] contextid
*
* mic_header piece of checksum data ends here.
*
* int-cksum - encoded length not constant, calculated
* ---------
* [??] 03 Type 3
* [??] ?? encoded length
* [??] ?? md5zbit
* [??] int-cksum (NID_md5 = 16)
*
* maximum SPKM-MIC innercontext token length =
* 10 + encoded contextid_size(17 max) + 2 + encoded
* cksum_size (17 maxfor NID_md5) = 46
*/
/*
* spkm3_mic_header()
*
* Prepare the SPKM_MIC_TOK mic-header for check-sum calculation
* elen: 16 byte context id asn1 bitstring encoded length
*/
void
spkm3_mic_header(unsigned char **hdrbuf, unsigned int *hdrlen, unsigned char *ctxdata, int elen, int zbit)
{
char *hptr = *hdrbuf;
char *top = *hdrbuf;
*(u8 *)hptr++ = 0x30;
*(u8 *)hptr++ = elen + 7; /* on the wire header length */
/* tokenid */
*(u8 *)hptr++ = 0x02;
*(u8 *)hptr++ = 0x02;
*(u8 *)hptr++ = 0x01;
*(u8 *)hptr++ = 0x01;
/* coniextid */
*(u8 *)hptr++ = 0x03;
*(u8 *)hptr++ = elen + 1; /* add 1 to include zbit */
*(u8 *)hptr++ = zbit;
memcpy(hptr, ctxdata, elen);
hptr += elen;
*hdrlen = hptr - top;
}
/*
* spkm3_mic_innercontext_token()
*
* *tokp points to the beginning of the SPKM_MIC token described
* in rfc 2025, section 3.2.1:
*
* toklen is the inner token length
*/
void
spkm3_make_mic_token(unsigned char **tokp, int toklen, struct xdr_netobj *mic_hdr, struct xdr_netobj *md5cksum, int md5elen, int md5zbit)
{
unsigned char *ict = *tokp;
*(u8 *)ict++ = 0xa4;
*(u8 *)ict++ = toklen;
memcpy(ict, mic_hdr->data, mic_hdr->len);
ict += mic_hdr->len;
*(u8 *)ict++ = 0x03;
*(u8 *)ict++ = md5elen + 1; /* add 1 to include zbit */
*(u8 *)ict++ = md5zbit;
memcpy(ict, md5cksum->data, md5elen);
}
u32
spkm3_verify_mic_token(unsigned char **tokp, int *mic_hdrlen, unsigned char **cksum)
{
struct xdr_netobj spkm3_ctx_id = {.len =0, .data = NULL};
unsigned char *ptr = *tokp;
int ctxelen;
u32 ret = GSS_S_DEFECTIVE_TOKEN;
/* spkm3 innercontext token preamble */
if ((ptr[0] != 0xa4) || (ptr[2] != 0x30)) {
dprintk("RPC: BAD SPKM ictoken preamble\n");
goto out;
}
*mic_hdrlen = ptr[3];
/* token type */
if ((ptr[4] != 0x02) || (ptr[5] != 0x02)) {
dprintk("RPC: BAD asn1 SPKM3 token type\n");
goto out;
}
/* only support SPKM_MIC_TOK */
if((ptr[6] != 0x01) || (ptr[7] != 0x01)) {
dprintk("RPC: ERROR unsupported SPKM3 token \n");
goto out;
}
/* contextid */
if (ptr[8] != 0x03) {
dprintk("RPC: BAD SPKM3 asn1 context-id type\n");
goto out;
}
ctxelen = ptr[9];
if (ctxelen > 17) { /* length includes asn1 zbit octet */
dprintk("RPC: BAD SPKM3 contextid len %d\n", ctxelen);
goto out;
}
/* ignore ptr[10] */
if(!decode_asn1_bitstring(&spkm3_ctx_id, &ptr[11], ctxelen - 1, 16))
goto out;
/*
* in the current implementation: the optional int-alg is not present
* so the default int-alg (md5) is used the optional snd-seq field is
* also not present
*/
if (*mic_hdrlen != 6 + ctxelen) {
dprintk("RPC: BAD SPKM_ MIC_TOK header len %d: we only support default int-alg (should be absent) and do not support snd-seq\n", *mic_hdrlen);
goto out;
}
/* checksum */
*cksum = (&ptr[10] + ctxelen); /* ctxelen includes ptr[10] */
ret = GSS_S_COMPLETE;
out:
kfree(spkm3_ctx_id.data);
return ret;
}
