svc_auth_gss.c

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/*
  svc_auth_gss.c
 
  Copyright (c) 2000 The Regents of the University of Michigan.
  All rights reserved.
 
  Copyright (c) 2000 Dug Song <dugsong@UMICH.EDU>.
  All rights reserved, all wrongs reversed.
 
  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 <wintirpc.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <rpc/rpc.h>
#include <gssapi/gssapi.h>
 
extern SVCAUTH svc_auth_none;
 
/*
 * from mit-krb5-1.2.1 mechglue/mglueP.h:
 * Array of context IDs typed by mechanism OID
 */
typedef struct gss_union_ctx_id_t {
  gss_OID     mech_type;
  gss_ctx_id_t    internal_ctx_id;
} gss_union_ctx_id_desc, *gss_union_ctx_id_t;
 
 
 
static bool_t   svcauth_gss_destroy();
static bool_t   svcauth_gss_wrap();
static bool_t   svcauth_gss_unwrap();
 
struct svc_auth_ops svc_auth_gss_ops = {
    svcauth_gss_wrap,
    svcauth_gss_unwrap,
    svcauth_gss_destroy
};
 
struct svc_rpc_gss_data {
    bool_t          established;    /* context established */
    gss_ctx_id_t        ctx;        /* context id */
    struct rpc_gss_sec  sec;        /* security triple */
    gss_buffer_desc     cname;      /* GSS client name */
    u_int           seq;        /* sequence number */
    u_int           win;        /* sequence window */
    u_int           seqlast;    /* last sequence number */
    u_int32_t       seqmask;    /* bitmask of seqnums */
    gss_name_t      client_name;    /* unparsed name string */
};
 
#define SVCAUTH_PRIVATE(auth) \
    ((struct svc_rpc_gss_data *)(auth)->svc_ah_private)
 
/* Global server credentials. */
gss_cred_id_t       _svcauth_gss_creds;
static gss_name_t   _svcauth_gss_name = NULL;
 
bool_t
svcauth_gss_set_svc_name(gss_name_t name)
{
    OM_uint32   maj_stat, min_stat;
 
    log_debug("in svcauth_gss_set_svc_name()");
 
    if (_svcauth_gss_name != NULL) {
        maj_stat = gss_release_name(&min_stat, &_svcauth_gss_name);
 
        if (maj_stat != GSS_S_COMPLETE) {
            log_status("gss_release_name", maj_stat, min_stat);
            return (FALSE);
        }
        _svcauth_gss_name = NULL;
    }
    maj_stat = gss_duplicate_name(&min_stat, name, &_svcauth_gss_name);
 
    if (maj_stat != GSS_S_COMPLETE) {
        log_status("gss_duplicate_name", maj_stat, min_stat);
        return (FALSE);
    }
 
    return (TRUE);
}
 
static bool_t
svcauth_gss_import_name(char *service)
{
    gss_name_t  name;
    gss_buffer_desc namebuf;
    OM_uint32   maj_stat, min_stat;
 
    log_debug("in svcauth_gss_import_name()");
 
    namebuf.value = service;
    namebuf.length = strlen(service);
 
    maj_stat = gss_import_name(&min_stat, &namebuf,
                   (gss_OID)GSS_C_NT_HOSTBASED_SERVICE, &name);
 
    if (maj_stat != GSS_S_COMPLETE) {
        log_status("gss_import_name", maj_stat, min_stat);
        return (FALSE);
    }
    if (svcauth_gss_set_svc_name(name) != TRUE) {
        gss_release_name(&min_stat, &name);
        return (FALSE);
    }
    return (TRUE);
}
 
static bool_t
svcauth_gss_acquire_cred(void)
{
    OM_uint32   maj_stat, min_stat;
 
    log_debug("in svcauth_gss_acquire_cred()");
 
    maj_stat = gss_acquire_cred(&min_stat, _svcauth_gss_name, 0,
                    GSS_C_NULL_OID_SET, GSS_C_ACCEPT,
                    &_svcauth_gss_creds, NULL, NULL);
 
    if (maj_stat != GSS_S_COMPLETE) {
        log_status("gss_acquire_cred", maj_stat, min_stat);
        return (FALSE);
    }
    return (TRUE);
}
 
static bool_t
svcauth_gss_release_cred(void)
{
    OM_uint32   maj_stat, min_stat;
 
    log_debug("in svcauth_gss_release_cred()");
 
    maj_stat = gss_release_cred(&min_stat, &_svcauth_gss_creds);
 
    if (maj_stat != GSS_S_COMPLETE) {
        log_status("gss_release_cred", maj_stat, min_stat);
        return (FALSE);
    }
 
    _svcauth_gss_creds = NULL;
 
    return (TRUE);
}
 
static bool_t
svcauth_gss_accept_sec_context(struct svc_req *rqst,
                   struct rpc_gss_init_res *gr)
{
    struct svc_rpc_gss_data *gd;
    struct rpc_gss_cred *gc;
    gss_buffer_desc      recv_tok, seqbuf, checksum;
    gss_OID          mech;
    OM_uint32        maj_stat = 0, min_stat = 0, ret_flags, seq;
 
    log_debug("in svcauth_gss_accept_context()");
 
    gd = SVCAUTH_PRIVATE(rqst->rq_xprt->xp_auth);
    gc = (struct rpc_gss_cred *)rqst->rq_clntcred;
    memset(gr, 0, sizeof(*gr));
 
    /* Deserialize arguments. */
    memset(&recv_tok, 0, sizeof(recv_tok));
 
    if (!svc_getargs(rqst->rq_xprt, (xdrproc_t)xdr_rpc_gss_init_args,
             (caddr_t)&recv_tok))
        return (FALSE);
 
    gr->gr_major = gss_accept_sec_context(&gr->gr_minor,
                          &gd->ctx,
                          _svcauth_gss_creds,
                          &recv_tok,
                          GSS_C_NO_CHANNEL_BINDINGS,
                          &gd->client_name,
                          &mech,
                          &gr->gr_token,
                          &ret_flags,
                          NULL,
                          NULL);
 
    if (gr->gr_major != GSS_S_COMPLETE &&
        gr->gr_major != GSS_S_CONTINUE_NEEDED) {
        log_status("accept_sec_context", gr->gr_major, gr->gr_minor);
        gd->ctx = GSS_C_NO_CONTEXT;
        gss_release_buffer(&min_stat, &gr->gr_token);
        return (FALSE);
    }
    /* ANDROS: krb5 mechglue returns ctx of size 8 - two pointers,
     * one to the mechanism oid, one to the internal_ctx_id */
    if ((gr->gr_ctx.value = mem_alloc(sizeof(gss_union_ctx_id_desc))) == NULL) {
        fprintf(stderr, "svcauth_gss_accept_context: out of memory\n");
        return (FALSE);
    }
    memcpy(gr->gr_ctx.value, gd->ctx, sizeof(gss_union_ctx_id_desc));
    gr->gr_ctx.length = sizeof(gss_union_ctx_id_desc);
 
    /* ANDROS: change for debugging linux kernel version...
    gr->gr_win = sizeof(gd->seqmask) * 8;
    */
    gr->gr_win = 0x00000005;
 
    /* Save client info. */
    gd->sec.mech = mech;
    gd->sec.qop = GSS_C_QOP_DEFAULT;
    gd->sec.svc = gc->gc_svc;
    gd->seq = gc->gc_seq;
    gd->win = gr->gr_win;
 
    if (gr->gr_major == GSS_S_COMPLETE) {
        maj_stat = gss_display_name(&min_stat, gd->client_name,
                        &gd->cname, &gd->sec.mech);
        if (maj_stat != GSS_S_COMPLETE) {
            log_status("display_name", maj_stat, min_stat);
            return (FALSE);
        }
#ifdef DEBUG
#ifdef HAVE_KRB5
        {
            gss_buffer_desc mechname;
 
            gss_oid_to_str(&min_stat, mech, &mechname);
 
            log_debug("accepted context for %.*s with "
                  "<mech %.*s, qop %d, svc %d>",
                  gd->cname.length, (char *)gd->cname.value,
                  mechname.length, (char *)mechname.value,
                  gd->sec.qop, gd->sec.svc);
 
            gss_release_buffer(&min_stat, &mechname);
        }
#elif HAVE_HEIMDAL
        log_debug("accepted context for %.*s with "
              "<mech {}, qop %d, svc %d>",
              gd->cname.length, (char *)gd->cname.value,
              gd->sec.qop, gd->sec.svc);
#endif
#endif /* DEBUG */
        seq = htonl(gr->gr_win);
        seqbuf.value = &seq;
        seqbuf.length = sizeof(seq);
 
        maj_stat = gss_sign(&min_stat, gd->ctx, GSS_C_QOP_DEFAULT,
                    &seqbuf, &checksum);
 
        if (maj_stat != GSS_S_COMPLETE)
            return (FALSE);
 
        rqst->rq_xprt->xp_verf.oa_flavor = RPCSEC_GSS;
        rqst->rq_xprt->xp_verf.oa_base = checksum.value;
        rqst->rq_xprt->xp_verf.oa_length = checksum.length;
    }
    return (TRUE);
}
 
static bool_t
svcauth_gss_validate(struct svc_rpc_gss_data *gd, struct rpc_msg *msg)
{
    struct opaque_auth  *oa;
    gss_buffer_desc      rpcbuf, checksum;
    OM_uint32        maj_stat, min_stat, qop_state;
    u_char           rpchdr[128];
    int32_t         *buf;
 
    log_debug("in svcauth_gss_validate()");
 
    memset(rpchdr, 0, sizeof(rpchdr));
 
    /* XXX - Reconstruct RPC header for signing (from xdr_callmsg). */
    oa = &msg->rm_call.cb_cred;
    if (oa->oa_length > MAX_AUTH_BYTES)
        return (FALSE);
    
    /* 8 XDR units from the IXDR macro calls. */
    if (sizeof(rpchdr) < (8 * BYTES_PER_XDR_UNIT +
            RNDUP(oa->oa_length)))
        return (FALSE);
 
    buf = (int32_t *)rpchdr;
    IXDR_PUT_LONG(buf, msg->rm_xid);
    IXDR_PUT_ENUM(buf, msg->rm_direction);
    IXDR_PUT_LONG(buf, msg->rm_call.cb_rpcvers);
    IXDR_PUT_LONG(buf, msg->rm_call.cb_prog);
    IXDR_PUT_LONG(buf, msg->rm_call.cb_vers);
    IXDR_PUT_LONG(buf, msg->rm_call.cb_proc);
    IXDR_PUT_ENUM(buf, oa->oa_flavor);
    IXDR_PUT_LONG(buf, oa->oa_length);
    if (oa->oa_length) {
        memcpy((caddr_t)buf, oa->oa_base, oa->oa_length);
        buf += RNDUP(oa->oa_length) / sizeof(int32_t);
    }
    rpcbuf.value = rpchdr;
    rpcbuf.length = (u_char *)buf - rpchdr;
 
    checksum.value = msg->rm_call.cb_verf.oa_base;
    checksum.length = msg->rm_call.cb_verf.oa_length;
 
    maj_stat = gss_verify_mic(&min_stat, gd->ctx, &rpcbuf, &checksum,
                  &qop_state);
 
    if (maj_stat != GSS_S_COMPLETE) {
        log_status("gss_verify_mic", maj_stat, min_stat);
        return (FALSE);
    }
    return (TRUE);
}
 
bool_t
svcauth_gss_nextverf(struct svc_req *rqst, u_int num)
{
    struct svc_rpc_gss_data *gd;
    gss_buffer_desc      signbuf, checksum;
    OM_uint32        maj_stat, min_stat;
 
    log_debug("in svcauth_gss_nextverf()");
 
    if (rqst->rq_xprt->xp_auth == NULL)
        return (FALSE);
 
    gd = SVCAUTH_PRIVATE(rqst->rq_xprt->xp_auth);
 
    signbuf.value = &num;
    signbuf.length = sizeof(num);
 
    maj_stat = gss_get_mic(&min_stat, gd->ctx, gd->sec.qop,
                   &signbuf, &checksum);
 
    if (maj_stat != GSS_S_COMPLETE) {
        log_status("gss_get_mic", maj_stat, min_stat);
        return (FALSE);
    }
    rqst->rq_xprt->xp_verf.oa_flavor = RPCSEC_GSS;
    rqst->rq_xprt->xp_verf.oa_base = (caddr_t)checksum.value;
    rqst->rq_xprt->xp_verf.oa_length = (u_int)checksum.length;
 
    return (TRUE);
}
 
enum auth_stat
_svcauth_gss(struct svc_req *rqst, struct rpc_msg *msg, bool_t *no_dispatch)
{
    XDR          xdrs;
    SVCAUTH         *auth;
    struct svc_rpc_gss_data *gd;
    struct rpc_gss_cred *gc;
    struct rpc_gss_init_res  gr;
    int          call_stat, offset;
 
    log_debug("in svcauth_gss()");
 
    /* Initialize reply. */
    rqst->rq_xprt->xp_verf = _null_auth;
 
    /* Allocate and set up server auth handle. */
    if (rqst->rq_xprt->xp_auth == NULL ||
        rqst->rq_xprt->xp_auth == &svc_auth_none) {
        if ((auth = calloc(sizeof(*auth), 1)) == NULL) {
            fprintf(stderr, "svcauth_gss: out_of_memory\n");
            return (AUTH_FAILED);
        }
        if ((gd = calloc(sizeof(*gd), 1)) == NULL) {
            fprintf(stderr, "svcauth_gss: out_of_memory\n");
            return (AUTH_FAILED);
        }
        auth->svc_ah_ops = &svc_auth_gss_ops;
        auth->svc_ah_private = (caddr_t) gd;
        rqst->rq_xprt->xp_auth = auth;
    }
    else gd = SVCAUTH_PRIVATE(rqst->rq_xprt->xp_auth);
 
    /* Deserialize client credentials. */
    if (rqst->rq_cred.oa_length <= 0)
        return (AUTH_BADCRED);
 
    gc = (struct rpc_gss_cred *)rqst->rq_clntcred;
    memset(gc, 0, sizeof(*gc));
 
    xdrmem_create(&xdrs, rqst->rq_cred.oa_base,
              rqst->rq_cred.oa_length, XDR_DECODE);
 
    if (!xdr_rpc_gss_cred(&xdrs, gc)) {
        XDR_DESTROY(&xdrs);
        return (AUTH_BADCRED);
    }
    XDR_DESTROY(&xdrs);
 
    /* Check version. */
    if (gc->gc_v != RPCSEC_GSS_VERSION)
        return (AUTH_BADCRED);
 
    /* Check RPCSEC_GSS service. */
    if (gc->gc_svc != RPCSEC_GSS_SVC_NONE &&
        gc->gc_svc != RPCSEC_GSS_SVC_INTEGRITY &&
        gc->gc_svc != RPCSEC_GSS_SVC_PRIVACY)
        return (AUTH_BADCRED);
 
    /* Check sequence number. */
    if (gd->established) {
        if (gc->gc_seq > MAXSEQ)
            return (RPCSEC_GSS_CTXPROBLEM);
 
        if ((offset = gd->seqlast - gc->gc_seq) < 0) {
            gd->seqlast = gc->gc_seq;
            offset = 0 - offset;
            gd->seqmask <<= offset;
            offset = 0;
        }
        else if (offset >= gd->win || (gd->seqmask & (1 << offset))) {
            *no_dispatch = 1;
            return (RPCSEC_GSS_CTXPROBLEM);
        }
        gd->seq = gc->gc_seq;
        gd->seqmask |= (1 << offset);
    }
 
    if (gd->established) {
        rqst->rq_clntname = (char *)gd->client_name;
        rqst->rq_svcname = (char *)gd->ctx;
    }
 
    /* Handle RPCSEC_GSS control procedure. */
    switch (gc->gc_proc) {
 
    case RPCSEC_GSS_INIT:
    case RPCSEC_GSS_CONTINUE_INIT:
        if (rqst->rq_proc != NULLPROC)
            return (AUTH_FAILED);       /* XXX ? */
 
        if (_svcauth_gss_name == NULL) {
            if (!svcauth_gss_import_name("nfs"))
                return (AUTH_FAILED);
        }
 
        if (!svcauth_gss_acquire_cred())
            return (AUTH_FAILED);
 
        if (!svcauth_gss_accept_sec_context(rqst, &gr))
            return (AUTH_REJECTEDCRED);
 
        if (!svcauth_gss_nextverf(rqst, htonl(gr.gr_win)))
            return (AUTH_FAILED);
 
        *no_dispatch = TRUE;
 
        call_stat = svc_sendreply(rqst->rq_xprt, 
            (xdrproc_t)xdr_rpc_gss_init_res, (caddr_t)&gr);
 
        if (!call_stat)
            return (AUTH_FAILED);
 
        if (gr.gr_major == GSS_S_COMPLETE)
            gd->established = TRUE;
 
        break;
 
    case RPCSEC_GSS_DATA:
        if (!svcauth_gss_validate(gd, msg))
            return (RPCSEC_GSS_CREDPROBLEM);
 
        if (!svcauth_gss_nextverf(rqst, htonl(gc->gc_seq)))
            return (AUTH_FAILED);
        break;
 
    case RPCSEC_GSS_DESTROY:
        if (rqst->rq_proc != NULLPROC)
            return (AUTH_FAILED);       /* XXX ? */
 
        if (!svcauth_gss_validate(gd, msg))
            return (RPCSEC_GSS_CREDPROBLEM);
 
        if (!svcauth_gss_nextverf(rqst, htonl(gc->gc_seq)))
            return (AUTH_FAILED);
 
        if (!svcauth_gss_release_cred())
            return (AUTH_FAILED);
 
        SVCAUTH_DESTROY(rqst->rq_xprt->xp_auth);
        rqst->rq_xprt->xp_auth = &svc_auth_none;
 
        break;
 
    default:
        return (AUTH_REJECTEDCRED);
        break;
    }
    return (AUTH_OK);
}
 
bool_t
svcauth_gss_destroy(SVCAUTH *auth)
{
    struct svc_rpc_gss_data *gd;
    OM_uint32        min_stat;
 
    log_debug("in svcauth_gss_destroy()");
 
    gd = SVCAUTH_PRIVATE(auth);
 
    gss_delete_sec_context(&min_stat, &gd->ctx, GSS_C_NO_BUFFER);
    gss_release_buffer(&min_stat, &gd->cname);
 
    if (gd->client_name)
        gss_release_name(&min_stat, &gd->client_name);
 
    mem_free(gd, sizeof(*gd));
    mem_free(auth, sizeof(*auth));
 
    return (TRUE);
}
 
bool_t
svcauth_gss_wrap(SVCAUTH *auth, XDR *xdrs, xdrproc_t xdr_func, caddr_t xdr_ptr)
{
    struct svc_rpc_gss_data *gd;
 
    log_debug("in svcauth_gss_wrap()");
 
    gd = SVCAUTH_PRIVATE(auth);
 
    if (!gd->established || gd->sec.svc == RPCSEC_GSS_SVC_NONE) {
        return ((*xdr_func)(xdrs, xdr_ptr));
    }
    return (xdr_rpc_gss_data(xdrs, xdr_func, xdr_ptr,
                 gd->ctx, gd->sec.qop,
                 gd->sec.svc, gd->seq));
}
 
bool_t
svcauth_gss_unwrap(SVCAUTH *auth, XDR *xdrs, xdrproc_t xdr_func, caddr_t xdr_ptr)
{
    struct svc_rpc_gss_data *gd;
 
    log_debug("in svcauth_gss_unwrap()");
 
    gd = SVCAUTH_PRIVATE(auth);
 
    if (!gd->established || gd->sec.svc == RPCSEC_GSS_SVC_NONE) {
        return ((*xdr_func)(xdrs, xdr_ptr));
    }
    return (xdr_rpc_gss_data(xdrs, xdr_func, xdr_ptr,
                 gd->ctx, gd->sec.qop,
                 gd->sec.svc, gd->seq));
}
 
char *
svcauth_gss_get_principal(SVCAUTH *auth)
{
    struct svc_rpc_gss_data *gd;
    char *pname;
 
    gd = SVCAUTH_PRIVATE(auth);
 
    if (gd->cname.length == 0)
        return (NULL);
 
    if ((pname = malloc(gd->cname.length + 1)) == NULL)
        return (NULL);
 
    memcpy(pname, gd->cname.value, gd->cname.length);
    pname[gd->cname.length] = '\0';
 
    return (pname);
}