/*      $OpenBSD: auth_unix.c,v 1.30 2022/02/14 03:38:59 guenther Exp $ */

/*
 * Copyright (c) 2010, Oracle America, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * 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.
 *     * Neither the name of the "Oracle America, Inc." 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 BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   "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
 *   COPYRIGHT HOLDER 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.
 */

/*
 * auth_unix.c, Implements UNIX style authentication parameters. 
 *  
 * The system is very weak.  The client uses no encryption for its
 * credentials and only sends null verifiers.  The server sends backs
 * null verifiers or optionally a verifier that suggests a new short hand
 * for the credentials.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

#include <rpc/types.h>
#include <rpc/xdr.h>
#include <rpc/rpc.h>
#include <rpc/auth.h>
#include <rpc/auth_unix.h>

/*
 * Unix authenticator operations vector
 */
static void     authunix_nextverf(struct __rpc_auth *);
static bool_t   authunix_marshal(struct __rpc_auth *, XDR *);
static bool_t   authunix_validate(struct __rpc_auth *, struct opaque_auth *);
static bool_t   authunix_refresh(struct __rpc_auth *);
static void     authunix_destroy(struct __rpc_auth *);

static const struct auth_ops auth_unix_ops = {
        authunix_nextverf,
        authunix_marshal,
        authunix_validate,
        authunix_refresh,
        authunix_destroy
};

/*
 * This struct is pointed to by the ah_private field of an auth_handle.
 */
struct audata {
        struct opaque_auth      au_origcred;    /* original credentials */
        struct opaque_auth      au_shcred;      /* short hand cred */
        u_long                  au_shfaults;    /* short hand cache faults */
        char                    au_marshed[MAX_AUTH_BYTES];
        u_int                   au_mpos;        /* xdr pos at end of marshed */
};
#define AUTH_PRIVATE(auth)      ((struct audata *)auth->ah_private)

static void marshal_new_auth(AUTH *auth);


/*
 * Create a unix style authenticator.
 * Returns an auth handle with the given stuff in it.
 */
AUTH *
authunix_create(char *machname, int uid, int gid, int len, int *aup_gids)
{
        struct authunix_parms aup;
        char mymem[MAX_AUTH_BYTES];
        struct timeval now;
        XDR xdrs;
        AUTH *auth;
        struct audata *au;

        /*
         * Allocate and set up auth handle
         */
        auth = (AUTH *)mem_alloc(sizeof(*auth));
#ifndef KERNEL
        if (auth == NULL)
                return (NULL);
#endif
        au = (struct audata *)mem_alloc(sizeof(*au));
#ifndef KERNEL
        if (au == NULL) {
                free(auth);
                return (NULL);
        }
#endif
        auth->ah_ops = &auth_unix_ops;
        auth->ah_private = (caddr_t)au;
        auth->ah_verf = au->au_shcred = _null_auth;
        au->au_shfaults = 0;

        /*
         * fill in param struct from the given params
         */
        (void)WRAP(gettimeofday)(&now,  NULL);
        aup.aup_time = now.tv_sec;
        aup.aup_machname = machname;
        aup.aup_uid = uid;
        aup.aup_gid = gid;
        aup.aup_len = (u_int)len;
        aup.aup_gids = aup_gids;

        /*
         * Serialize the parameters into origcred
         */
        xdrmem_create(&xdrs, mymem, MAX_AUTH_BYTES, XDR_ENCODE);
        if (!xdr_authunix_parms(&xdrs, &aup)) 
                goto authfail;  
        au->au_origcred.oa_length = len = XDR_GETPOS(&xdrs);
        au->au_origcred.oa_flavor = AUTH_UNIX;
#ifdef KERNEL
        au->au_origcred.oa_base = mem_alloc((u_int) len);
#else
        if ((au->au_origcred.oa_base = mem_alloc((u_int) len)) == NULL)
                goto authfail;  
#endif
        memcpy(au->au_origcred.oa_base, mymem, (u_int)len);

        /*
         * set auth handle to reflect new cred.
         */
        auth->ah_cred = au->au_origcred;
        marshal_new_auth(auth);
        return (auth);

authfail:
        XDR_DESTROY(&xdrs);
        free(au);
        free(auth);
        return (NULL);
}
DEF_WEAK(authunix_create);


/*
 * Some servers will refuse mounts if the group list is larger
 * than it expects (like 8). This allows the application to set
 * the maximum size of the group list that will be sent.
 */
static int maxgrplist = NGRPS;

void
set_rpc_maxgrouplist(int num)
{
        if (num < NGRPS)
                maxgrplist = num;
}

/*
 * Returns an auth handle with parameters determined by doing lots of
 * syscalls.
 */
AUTH *
authunix_create_default(void)
{
        int len, i;
        char machname[MAX_MACHINE_NAME + 1];
        uid_t uid;
        gid_t gid;
        gid_t gids[NGRPS];
        int gids2[NGRPS];

        if (gethostname(machname, sizeof machname) == -1)
                return (NULL);
        machname[MAX_MACHINE_NAME] = 0;
        uid = geteuid();
        gid = getegid();
        if ((len = getgroups(NGRPS, gids)) == -1)
                return (NULL);
        if (len > maxgrplist)
                len = maxgrplist;
        for (i = 0; i < len; i++)
                gids2[i] = gids[i];
        return (authunix_create(machname, uid, gid, len, gids2));
}
DEF_WEAK(authunix_create_default);

/*
 * authunix operations
 */
static void
authunix_nextverf(AUTH *auth)
{
        /* no action necessary */
}

static bool_t
authunix_marshal(AUTH *auth, XDR *xdrs)
{
        struct audata *au = AUTH_PRIVATE(auth);

        return (XDR_PUTBYTES(xdrs, au->au_marshed, au->au_mpos));
}

static bool_t
authunix_validate(AUTH *auth, struct opaque_auth *verf)
{
        struct audata *au;
        XDR xdrs;

        if (verf->oa_flavor == AUTH_SHORT) {
                au = AUTH_PRIVATE(auth);
                xdrmem_create(&xdrs, verf->oa_base, verf->oa_length, XDR_DECODE);

                if (au->au_shcred.oa_base != NULL) {
                        mem_free(au->au_shcred.oa_base,
                            au->au_shcred.oa_length);
                        au->au_shcred.oa_base = NULL;
                }
                if (xdr_opaque_auth(&xdrs, &au->au_shcred)) {
                        auth->ah_cred = au->au_shcred;
                } else {
                        xdrs.x_op = XDR_FREE;
                        (void)xdr_opaque_auth(&xdrs, &au->au_shcred);
                        au->au_shcred.oa_base = NULL;
                        auth->ah_cred = au->au_origcred;
                }
                marshal_new_auth(auth);
        }
        return (TRUE);
}

static bool_t
authunix_refresh(AUTH *auth)
{
        struct audata *au = AUTH_PRIVATE(auth);
        struct authunix_parms aup;
        struct timeval now;
        XDR xdrs;
        int stat;

        if (auth->ah_cred.oa_base == au->au_origcred.oa_base) {
                /* there is no hope.  Punt */
                return (FALSE);
        }
        au->au_shfaults ++;

        /* first deserialize the creds back into a struct authunix_parms */
        aup.aup_machname = NULL;
        aup.aup_gids = NULL;
        xdrmem_create(&xdrs, au->au_origcred.oa_base,
            au->au_origcred.oa_length, XDR_DECODE);
        stat = xdr_authunix_parms(&xdrs, &aup);
        if (! stat) 
                goto done;

        /* update the time and serialize in place */
        (void)WRAP(gettimeofday)(&now, NULL);
        aup.aup_time = now.tv_sec;
        xdrs.x_op = XDR_ENCODE;
        XDR_SETPOS(&xdrs, 0);
        stat = xdr_authunix_parms(&xdrs, &aup);
        if (! stat)
                goto done;
        auth->ah_cred = au->au_origcred;
        marshal_new_auth(auth);
done:
        /* free the struct authunix_parms created by deserializing */
        xdrs.x_op = XDR_FREE;
        (void)xdr_authunix_parms(&xdrs, &aup);
        XDR_DESTROY(&xdrs);
        return (stat);
}

static void
authunix_destroy(AUTH *auth)
{
        struct audata *au = AUTH_PRIVATE(auth);

        mem_free(au->au_origcred.oa_base, au->au_origcred.oa_length);

        if (au->au_shcred.oa_base != NULL)
                mem_free(au->au_shcred.oa_base, au->au_shcred.oa_length);

        mem_free(auth->ah_private, sizeof(struct audata));

        if (auth->ah_verf.oa_base != NULL)
                mem_free(auth->ah_verf.oa_base, auth->ah_verf.oa_length);

        mem_free((caddr_t)auth, sizeof(*auth));
}

/*
 * Marshals (pre-serializes) an auth struct.
 * sets private data, au_marshed and au_mpos
 */
static void
marshal_new_auth(AUTH *auth)
{
        XDR             xdr_stream;
        XDR     *xdrs = &xdr_stream;
        struct audata *au = AUTH_PRIVATE(auth);

        xdrmem_create(xdrs, au->au_marshed, MAX_AUTH_BYTES, XDR_ENCODE);
        if ((! xdr_opaque_auth(xdrs, &(auth->ah_cred))) ||
            (! xdr_opaque_auth(xdrs, &(auth->ah_verf)))) {
                /* XXX nothing we can do */
        } else {
                au->au_mpos = XDR_GETPOS(xdrs);
        }
        XDR_DESTROY(xdrs);
}