xref: /openbsd-src/lib/libc/rpc/auth_unix.c (revision 8d4335cb9be89a0813640b54b89d23507be8c423)

/*	$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);
}