RPCSEC_GSS: Add the spkm3 common and client-side code.

Signed-off-by: Andy Adamson <andros@citi.umich.edu>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Trond Myklebust <trond.myklebust@fys.uio.no>

fs/Kconfig

@@ -1560,6 +1560,22 @@ config RPCSEC_GSS_KRB5
 
 	  If unsure, say N.
 
+config RPCSEC_GSS_SPKM3
+	tristate "Secure RPC: SPKM3 mechanism (EXPERIMENTAL)"
+	depends on SUNRPC && EXPERIMENTAL
+	select SUNRPC_GSS
+	select CRYPTO
+	select CRYPTO_MD5
+	select CRYPTO_DES
+	help
+	  Provides for secure RPC calls by means of a gss-api
+	  mechanism based on the SPKM3 public-key mechanism.
+
+	  Note: Requires an auxiliary userspace daemon which may be found on
+	  	http://www.citi.umich.edu/projects/nfsv4/
+
+	  If unsure, say N.
+
 config SMB_FS
 	tristate "SMB file system support (to mount Windows shares etc.)"
 	depends on INET

include/linux/sunrpc/gss_spkm3.h

+/*
+ *  linux/include/linux/sunrpc/gss_spkm3.h
+ *
+ *  Copyright (c) 2000 The Regents of the University of Michigan.
+ *  All rights reserved.
+ *
+ *  Andy Adamson   <andros@umich.edu>
+ */
+
+#include <linux/sunrpc/auth_gss.h>
+#include <linux/sunrpc/gss_err.h>
+#include <linux/sunrpc/gss_asn1.h>
+
+struct spkm3_ctx {
+	struct xdr_netobj	ctx_id; /* per message context id */
+	int			qop;         /* negotiated qop */
+	struct xdr_netobj	mech_used;
+	unsigned int		ret_flags ;
+	unsigned int		req_flags ;
+	struct xdr_netobj	share_key;
+	int			conf_alg;
+	struct crypto_tfm*	derived_conf_key;
+	int			intg_alg;
+	struct crypto_tfm*	derived_integ_key;
+	int			keyestb_alg;   /* alg used to get share_key */
+	int			owf_alg;   /* one way function */
+};
+
+/* from openssl/objects.h */
+/* XXX need SEAL_ALG_NONE */
+#define NID_md5		4
+#define NID_dhKeyAgreement	28 
+#define NID_des_cbc		31 
+#define NID_sha1		64
+#define NID_cast5_cbc		108
+
+/* SPKM InnerContext Token types */
+
+#define SPKM_ERROR_TOK	3
+#define SPKM_MIC_TOK	4
+#define SPKM_WRAP_TOK	5
+#define SPKM_DEL_TOK	6
+
+u32 spkm3_make_token(struct spkm3_ctx *ctx, int qop_req, struct xdr_buf * text, struct xdr_netobj * token, int toktype);
+
+u32 spkm3_read_token(struct spkm3_ctx *ctx, struct xdr_netobj *read_token, struct xdr_buf *message_buffer, int *qop_state, int toktype);
+
+#define CKSUMTYPE_RSA_MD5            0x0007
+
+s32 make_checksum(s32 cksumtype, char *header, int hdrlen, struct xdr_buf *body,
+                   struct xdr_netobj *cksum);
+void asn1_bitstring_len(struct xdr_netobj *in, int *enclen, int *zerobits);
+int decode_asn1_bitstring(struct xdr_netobj *out, char *in, int enclen, 
+                   int explen);
+void spkm3_mic_header(unsigned char **hdrbuf, unsigned int *hdrlen, 
+                   unsigned char *ctxhdr, int elen, int zbit);
+void spkm3_make_mic_token(unsigned  char **tokp, int toklen, 
+                   struct xdr_netobj *mic_hdr,
+                   struct xdr_netobj *md5cksum, int md5elen, int md5zbit);
+u32 spkm3_verify_mic_token(unsigned char **tokp, int *mic_hdrlen, 
+                   unsigned char **cksum);

net/sunrpc/auth_gss/Makefile

@@ -12,3 +12,7 @@ obj-$(CONFIG_RPCSEC_GSS_KRB5) += rpcsec_gss_krb5.o
 rpcsec_gss_krb5-objs := gss_krb5_mech.o gss_krb5_seal.o gss_krb5_unseal.o \
 	gss_krb5_seqnum.o
 
+obj-$(CONFIG_RPCSEC_GSS_SPKM3) += rpcsec_gss_spkm3.o
+
+rpcsec_gss_spkm3-objs := gss_spkm3_mech.o gss_spkm3_seal.o gss_spkm3_unseal.o \
+	gss_spkm3_token.o

net/sunrpc/auth_gss/gss_spkm3_mech.c

+/*
+ *  linux/net/sunrpc/gss_spkm3_mech.c
+ *
+ *  Copyright (c) 2003 The Regents of the University of Michigan.
+ *  All rights reserved.
+ *
+ *  Andy Adamson <andros@umich.edu>
+ *  J. Bruce Fields <bfields@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/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/sunrpc/auth.h>
+#include <linux/in.h>
+#include <linux/sunrpc/svcauth_gss.h>
+#include <linux/sunrpc/gss_spkm3.h>
+#include <linux/sunrpc/xdr.h>
+#include <linux/crypto.h>
+
+#ifdef RPC_DEBUG
+# define RPCDBG_FACILITY	RPCDBG_AUTH
+#endif
+
+struct xdr_netobj gss_mech_spkm3_oid =
+   {7, "\053\006\001\005\005\001\003"};
+
+static inline int
+get_bytes(char **ptr, const char *end, void *res, int len)
+{
+	char *p, *q;
+	p = *ptr;
+	q = p + len;
+	if (q > end || q < p)
+		return -1;
+	memcpy(res, p, len);
+	*ptr = q;
+	return 0;
+}
+
+static inline int
+get_netobj(char **ptr, const char *end, struct xdr_netobj *res)
+{
+	char *p, *q;
+	p = *ptr;
+	if (get_bytes(&p, end, &res->len, sizeof(res->len)))
+		return -1;
+	q = p + res->len;
+	if(res->len == 0)
+		goto out_nocopy;
+	if (q > end || q < p)
+		return -1;
+	if (!(res->data = kmalloc(res->len, GFP_KERNEL)))
+		return -1;
+	memcpy(res->data, p, res->len);
+out_nocopy:
+	*ptr = q;
+	return 0;
+}
+
+static inline int
+get_key(char **p, char *end, struct crypto_tfm **res, int *resalg)
+{
+	struct xdr_netobj	key = {
+		.len = 0,
+		.data = NULL,
+	};
+	int			alg_mode,setkey = 0;
+	char			*alg_name;
+
+	if (get_bytes(p, end, resalg, sizeof(int)))
+		goto out_err;
+	if ((get_netobj(p, end, &key)))
+		goto out_err;
+
+	switch (*resalg) {
+		case NID_des_cbc:
+			alg_name = "des";
+			alg_mode = CRYPTO_TFM_MODE_CBC;
+			setkey = 1;
+			break;
+		case NID_md5:
+			if (key.len == 0) {
+				dprintk("RPC: SPKM3 get_key: NID_md5 zero Key length\n");
+			}
+			alg_name = "md5";
+			alg_mode = 0;
+			setkey = 0;
+			break;
+		case NID_cast5_cbc:
+			dprintk("RPC: SPKM3 get_key: case cast5_cbc, UNSUPPORTED \n");
+			goto out_err;
+			break;
+		default:
+			dprintk("RPC: SPKM3 get_key: unsupported algorithm %d", *resalg);
+			goto out_err_free_key;
+	}
+	if (!(*res = crypto_alloc_tfm(alg_name, alg_mode)))
+		goto out_err_free_key;
+	if (setkey) {
+		if (crypto_cipher_setkey(*res, key.data, key.len))
+			goto out_err_free_tfm;
+	}
+
+	if(key.len > 0)
+		kfree(key.data);
+	return 0;
+
+out_err_free_tfm:
+	crypto_free_tfm(*res);
+out_err_free_key:
+	if(key.len > 0)
+		kfree(key.data);
+out_err:
+	return -1;
+}
+
+static u32
+gss_import_sec_context_spkm3(struct xdr_netobj *inbuf,
+				struct gss_ctx *ctx_id)
+{
+	char	*p = inbuf->data;
+	char	*end = inbuf->data + inbuf->len;
+	struct	spkm3_ctx *ctx;
+
+	if (!(ctx = kmalloc(sizeof(*ctx), GFP_KERNEL)))
+		goto out_err;
+	memset(ctx, 0, sizeof(*ctx));
+
+	if (get_netobj(&p, end, &ctx->ctx_id))
+		goto out_err_free_ctx;
+
+	if (get_bytes(&p, end, &ctx->qop, sizeof(ctx->qop)))
+		goto out_err_free_ctx_id;
+
+	if (get_netobj(&p, end, &ctx->mech_used))
+		goto out_err_free_mech;
+
+	if (get_bytes(&p, end, &ctx->ret_flags, sizeof(ctx->ret_flags)))
+		goto out_err_free_mech;
+
+	if (get_bytes(&p, end, &ctx->req_flags, sizeof(ctx->req_flags)))
+		goto out_err_free_mech;
+
+	if (get_netobj(&p, end, &ctx->share_key))
+		goto out_err_free_s_key;
+
+	if (get_key(&p, end, &ctx->derived_conf_key, &ctx->conf_alg)) {
+		dprintk("RPC: SPKM3 confidentiality key will be NULL\n");
+	}
+
+	if (get_key(&p, end, &ctx->derived_integ_key, &ctx->intg_alg)) {
+		dprintk("RPC: SPKM3 integrity key will be NULL\n");
+	}
+
+	if (get_bytes(&p, end, &ctx->owf_alg, sizeof(ctx->owf_alg)))
+		goto out_err_free_s_key;
+
+	if (get_bytes(&p, end, &ctx->owf_alg, sizeof(ctx->owf_alg)))
+		goto out_err_free_s_key;
+
+	if (p != end)
+		goto out_err_free_s_key;
+
+	ctx_id->internal_ctx_id = ctx;
+
+	dprintk("Succesfully imported new spkm context.\n");
+	return 0;
+
+out_err_free_s_key:
+	kfree(ctx->share_key.data);
+out_err_free_mech:
+	kfree(ctx->mech_used.data);
+out_err_free_ctx_id:
+	kfree(ctx->ctx_id.data);
+out_err_free_ctx:
+	kfree(ctx);
+out_err:
+	return GSS_S_FAILURE;
+}
+
+void
+gss_delete_sec_context_spkm3(void *internal_ctx) {
+	struct spkm3_ctx *sctx = internal_ctx;
+
+	if(sctx->derived_integ_key)
+		crypto_free_tfm(sctx->derived_integ_key);
+	if(sctx->derived_conf_key)
+		crypto_free_tfm(sctx->derived_conf_key);
+	if(sctx->share_key.data)
+		kfree(sctx->share_key.data);
+	if(sctx->mech_used.data)
+		kfree(sctx->mech_used.data);
+	kfree(sctx);
+}
+
+u32
+gss_verify_mic_spkm3(struct gss_ctx		*ctx,
+			struct xdr_buf		*signbuf,
+			struct xdr_netobj	*checksum,
+			u32		*qstate) {
+	u32 maj_stat = 0;
+	int qop_state = 0;
+	struct spkm3_ctx *sctx = ctx->internal_ctx_id;
+
+	dprintk("RPC: gss_verify_mic_spkm3 calling spkm3_read_token\n");
+	maj_stat = spkm3_read_token(sctx, checksum, signbuf, &qop_state,
+				   SPKM_MIC_TOK);
+
+	if (!maj_stat && qop_state)
+	    *qstate = qop_state;
+
+	dprintk("RPC: gss_verify_mic_spkm3 returning %d\n", maj_stat);
+	return maj_stat;
+}
+
+u32
+gss_get_mic_spkm3(struct gss_ctx	*ctx,
+		     u32		qop,
+		     struct xdr_buf	*message_buffer,
+		     struct xdr_netobj	*message_token) {
+	u32 err = 0;
+	struct spkm3_ctx *sctx = ctx->internal_ctx_id;
+
+	dprintk("RPC: gss_get_mic_spkm3\n");
+
+	err = spkm3_make_token(sctx, qop, message_buffer,
+			      message_token, SPKM_MIC_TOK);
+	return err;
+}
+
+static struct gss_api_ops gss_spkm3_ops = {
+	.gss_import_sec_context	= gss_import_sec_context_spkm3,
+	.gss_get_mic		= gss_get_mic_spkm3,
+	.gss_verify_mic		= gss_verify_mic_spkm3,
+	.gss_delete_sec_context	= gss_delete_sec_context_spkm3,
+};
+
+static struct pf_desc gss_spkm3_pfs[] = {
+	{RPC_AUTH_GSS_SPKM, 0, RPC_GSS_SVC_NONE, "spkm3"},
+	{RPC_AUTH_GSS_SPKMI, 0, RPC_GSS_SVC_INTEGRITY, "spkm3i"},
+};
+
+static struct gss_api_mech gss_spkm3_mech = {
+	.gm_name	= "spkm3",
+	.gm_owner	= THIS_MODULE,
+	.gm_ops		= &gss_spkm3_ops,
+	.gm_pf_num	= ARRAY_SIZE(gss_spkm3_pfs),
+	.gm_pfs		= gss_spkm3_pfs,
+};
+
+static int __init init_spkm3_module(void)
+{
+	int status;
+
+	status = gss_mech_register(&gss_spkm3_mech);
+	if (status)
+		printk("Failed to register spkm3 gss mechanism!\n");
+	return 0;
+}
+
+static void __exit cleanup_spkm3_module(void)
+{
+	gss_mech_unregister(&gss_spkm3_mech);
+}
+
+MODULE_LICENSE("GPL");
+module_init(init_spkm3_module);
+module_exit(cleanup_spkm3_module);

net/sunrpc/auth_gss/gss_spkm3_seal.c

+/*
+ *  linux/net/sunrpc/gss_spkm3_seal.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
+
+/*
+ * spkm3_make_token()
+ *
+ * Only SPKM_MIC_TOK with md5 intg-alg is supported
+ */
+
+u32
+spkm3_make_token(struct spkm3_ctx *ctx, int qop_req,
+		   struct xdr_buf * text, struct xdr_netobj * token,
+		   int toktype)
+{
+	s32			checksum_type;
+	char			tokhdrbuf[25];
+	struct xdr_netobj	md5cksum = {.len = 0, .data = NULL};
+	struct xdr_netobj	mic_hdr = {.len = 0, .data = tokhdrbuf};
+	int			tmsglen, tokenlen = 0;
+	unsigned char		*ptr;
+	s32			now;
+	int			ctxelen = 0, ctxzbit = 0;
+	int			md5elen = 0, md5zbit = 0;
+
+	dprintk("RPC: spkm3_make_token\n");
+
+	now = jiffies;
+	if (qop_req != 0)
+		goto out_err;
+
+	if (ctx->ctx_id.len != 16) {
+		dprintk("RPC: spkm3_make_token BAD ctx_id.len %d\n",
+			ctx->ctx_id.len);
+		goto out_err;
+	}
+		
+	switch (ctx->intg_alg) {
+		case NID_md5:
+			checksum_type = CKSUMTYPE_RSA_MD5;
+			break;
+		default:
+			dprintk("RPC: gss_spkm3_seal: ctx->signalg %d not"
+				" supported\n", ctx->intg_alg);
+			goto out_err;
+	}
+	/* XXX since we don't support WRAP, perhaps we don't care... */
+	if (ctx->conf_alg != NID_cast5_cbc) {
+		dprintk("RPC: gss_spkm3_seal: ctx->sealalg %d not supported\n",
+			ctx->conf_alg);
+		goto out_err;
+	}
+
+	if (toktype == SPKM_MIC_TOK) {
+		tmsglen = 0;
+		/* Calculate checksum over the mic-header */
+		asn1_bitstring_len(&ctx->ctx_id, &ctxelen, &ctxzbit);
+		spkm3_mic_header(&mic_hdr.data, &mic_hdr.len, ctx->ctx_id.data,
+		                         ctxelen, ctxzbit);
+
+		if (make_checksum(checksum_type, mic_hdr.data, mic_hdr.len, 
+		                             text, &md5cksum))
+			goto out_err;
+
+		asn1_bitstring_len(&md5cksum, &md5elen, &md5zbit);
+		tokenlen = 10 + ctxelen + 1 + 2 + md5elen + 1;
+
+		/* Create token header using generic routines */
+		token->len = g_token_size(&ctx->mech_used, tokenlen + tmsglen);
+
+		ptr = token->data;
+		g_make_token_header(&ctx->mech_used, tokenlen + tmsglen, &ptr);
+
+		spkm3_make_mic_token(&ptr, tokenlen, &mic_hdr, &md5cksum, md5elen, md5zbit);
+	} else if (toktype == SPKM_WRAP_TOK) { /* Not Supported */
+		dprintk("RPC: gss_spkm3_seal: SPKM_WRAP_TOK not supported\n");
+		goto out_err;
+	}
+	kfree(md5cksum.data);
+
+	/* XXX need to implement sequence numbers, and ctx->expired */
+
+	return  GSS_S_COMPLETE;
+out_err:
+	if (md5cksum.data) 
+		kfree(md5cksum.data);
+	token->data = 0;
+	token->len = 0;
+	return GSS_S_FAILURE;
+}

net/sunrpc/auth_gss/gss_spkm3_token.c

+/*
+ *  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 = kmalloc(explen,GFP_KERNEL)))
+		return 0;
+	out->len = explen;
+	memset(out->data, 0, 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: 
+ *
+ */
+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 - 2; 
+	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:
+	if (spkm3_ctx_id.data)
+		kfree(spkm3_ctx_id.data);
+	return ret;
+}
+

net/sunrpc/auth_gss/gss_spkm3_unseal.c

+/*
+ *  linux/net/sunrpc/gss_spkm3_unseal.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/crypto.h>
+
+#ifdef RPC_DEBUG
+# define RPCDBG_FACILITY        RPCDBG_AUTH
+#endif
+
+/*
+ * spkm3_read_token()
+ * 
+ * only SPKM_MIC_TOK with md5 intg-alg is supported
+ */
+u32
+spkm3_read_token(struct spkm3_ctx *ctx,
+		struct xdr_netobj *read_token,    /* checksum */
+		struct xdr_buf *message_buffer, /* signbuf */
+		int *qop_state, int toktype)
+{
+	s32			code;
+	struct xdr_netobj	wire_cksum = {.len =0, .data = NULL};
+	struct xdr_netobj	md5cksum = {.len = 0, .data = NULL};
+	unsigned char		*ptr = (unsigned char *)read_token->data;
+	unsigned char           *cksum;
+	int			bodysize, md5elen;
+	int			mic_hdrlen;
+	u32			ret = GSS_S_DEFECTIVE_TOKEN;
+
+	dprintk("RPC: spkm3_read_token read_token->len %d\n", read_token->len);
+
+	if (g_verify_token_header((struct xdr_netobj *) &ctx->mech_used,
+					&bodysize, &ptr, read_token->len))
+		goto out;
+
+	/* decode the token */
+
+	if (toktype == SPKM_MIC_TOK) {
+
+		if ((ret = spkm3_verify_mic_token(&ptr, &mic_hdrlen, &cksum))) 
+			goto out;
+
+		if (*cksum++ != 0x03) {
+			dprintk("RPC: spkm3_read_token BAD checksum type\n");
+			goto out;
+		}
+		md5elen = *cksum++; 
+		cksum++; 	/* move past the zbit */
+	
+		if(!decode_asn1_bitstring(&wire_cksum, cksum, md5elen - 1, 16))
+			goto out;
+
+		/* HARD CODED FOR MD5 */
+
+		/* compute the checksum of the message.
+		*  ptr + 2 = start of header piece of checksum
+		*  mic_hdrlen + 2 = length of header piece of checksum
+		*/
+		ret = GSS_S_DEFECTIVE_TOKEN;
+		code = make_checksum(CKSUMTYPE_RSA_MD5, ptr + 2, 
+					mic_hdrlen + 2, 
+		                        message_buffer, &md5cksum);
+
+		if (code)
+			goto out;
+
+		dprintk("RPC: spkm3_read_token: digest wire_cksum.len %d:\n", 
+			wire_cksum.len);
+		dprintk("          md5cksum.data\n");
+		print_hexl((u32 *) md5cksum.data, 16, 0);
+		dprintk("          cksum.data:\n");
+		print_hexl((u32 *) wire_cksum.data, wire_cksum.len, 0);
+
+		ret = GSS_S_BAD_SIG;
+		code = memcmp(md5cksum.data, wire_cksum.data, wire_cksum.len);
+		if (code)
+			goto out;
+
+	} else { 
+		dprintk("RPC: BAD or UNSUPPORTED SPKM3 token type: %d\n",toktype);
+		goto out;
+	}
+
+	/* XXX: need to add expiration and sequencing */
+	ret = GSS_S_COMPLETE;
+out:
+	if (md5cksum.data) 
+		kfree(md5cksum.data);
+	if (wire_cksum.data) 
+		kfree(wire_cksum.data);
+	return ret;
+}