src/auth_unix.c

/*
 * Copyright (c) 2009, Sun Microsystems, Inc.
 * All rights reserved.
 *
 * 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 Sun Microsystems, 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.
 */

#include <config.h>
#include <sys/cdefs.h>

/*
 * auth_unix.c, Implements UNIX style authentication parameters.
 *
 * Copyright (C) 1984, Sun Microsystems, Inc.
 *
 * The system is very weak.  The client uses no encryption for it's
 * 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 <sys/param.h>

#include <assert.h>
#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>

#include <rpc/types.h>
#include <misc/portable.h>
#include <reentrant.h>
#include <rpc/rpc.h>
#include <rpc/xdr.h>
#include <rpc/clnt.h>
#include <rpc/auth.h>
#include <rpc/auth_unix.h>

/* auth_unix.c */
static void authunix_nextverf (AUTH *);
static bool authunix_marshal (AUTH *, XDR *);
static bool authunix_validate (AUTH *, struct opaque_auth *);
static bool authunix_refresh (AUTH *, void *);
static void authunix_destroy (AUTH *);
static void marshal_new_auth (AUTH *);
static struct auth_ops *authunix_ops (void);

/*
 * 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)

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

    memset(&rpc_createerr, 0, sizeof(rpc_createerr));

    /*
     * Allocate and set up auth handle
     */
    au = NULL;
    auth = mem_alloc(sizeof(*auth));
#ifndef _KERNEL
    if (auth == NULL) {
        rpc_createerr.cf_stat = RPC_SYSTEMERROR;
        rpc_createerr.cf_error.re_errno = ENOMEM;
        goto cleanup_authunix_create;
    }
#endif
    au = mem_alloc(sizeof(*au));
#ifndef _KERNEL
    if (au == NULL) {
        rpc_createerr.cf_stat = RPC_SYSTEMERROR;
        rpc_createerr.cf_error.re_errno = ENOMEM;
        goto cleanup_authunix_create;
    }
#endif
    auth->ah_ops = authunix_ops();
    auth->ah_private = (caddr_t)au;
    auth->ah_verf = au->au_shcred = _null_auth;
    auth->ah_refcnt = 1;
    au->au_shfaults = 0;
    au->au_origcred.oa_base = NULL;

    /*
     * fill in param struct from the given params
     */
    (void)clock_gettime(CLOCK_MONOTONIC_FAST, &now);
    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)) {
        rpc_createerr.cf_stat = RPC_CANTENCODEARGS;
        goto cleanup_authunix_create;
    }
    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) {
        rpc_createerr.cf_stat = RPC_SYSTEMERROR;
        rpc_createerr.cf_error.re_errno = ENOMEM;
        goto cleanup_authunix_create;
    }
#endif
    memmove(au->au_origcred.oa_base, mymem, (size_t)len);

    /*
     * set auth handle to reflect new cred.
     */
    auth->ah_cred = au->au_origcred;
    marshal_new_auth(auth);
    auth_get(auth);  /* Reference for caller */
    return (auth);
#ifndef _KERNEL
cleanup_authunix_create:
    if (auth)
        mem_free(auth, sizeof(*auth));
    if (au) {
        if (au->au_origcred.oa_base)
            mem_free(au->au_origcred.oa_base, (u_int)len);
        mem_free(au, sizeof(*au));
    }
    return (NULL);
#endif
}

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

    memset(&rpc_createerr, 0, sizeof(rpc_createerr));

    if (gethostname(machname, sizeof machname) == -1) {
        rpc_createerr.cf_error.re_errno = errno;
        goto out_err;
    }
    machname[sizeof(machname) - 1] = 0;
    uid = geteuid();
    gid = getegid();

    /* According to glibc comments, an intervening setgroups(2)
     * call can increase the number of supplemental groups between
     * these two getgroups(2) calls. */
retry:
    len = getgroups(0, NULL);
    if (len == -1) {
        rpc_createerr.cf_error.re_errno = errno;
        goto out_err;
    }

    /* Bump allocation size.  A zero allocation size may result in a
     * NULL calloc(3) result, which is not reliably distinguishable
     * from a memory allocation error. */
    gids = mem_alloc((len + 1)*sizeof(gid_t));
    if (gids == NULL) {
        rpc_createerr.cf_error.re_errno = ENOMEM;
        goto out_err;
    }

    len = getgroups(len, gids);
    if (len == -1) {
        rpc_createerr.cf_error.re_errno = errno;
        mem_free(gids, 0); /* XXX */
        if (rpc_createerr.cf_error.re_errno == EINVAL) {
            rpc_createerr.cf_error.re_errno = 0;
            goto retry;
        }
        goto out_err;
    }

    /*
     * AUTH_UNIX sends on the wire only the first NGRPS groups in the
     * supplemental groups list.
     */
    if (len > NGRPS)
        len = NGRPS;

    /* XXX: interface problem; those should all have been unsigned */
    result = authunix_ncreate(machname, uid, gid, len, gids);
    mem_free(gids, 0); /* XXX */
    return result;

out_err:
    rpc_createerr.cf_stat = RPC_SYSTEMERROR;
    return NULL;
}

/*
 * authunix operations
 */

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

static bool
authunix_marshal(AUTH *auth, XDR *xdrs)
{
    struct audata *au;

    assert(auth != NULL);
    assert(xdrs != NULL);

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

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

    assert(auth != NULL);
    assert(verf != NULL);

    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
authunix_refresh(AUTH *auth, void *dummy)
{
    struct audata *au = AUTH_PRIVATE(auth);
    struct authunix_parms aup;
    struct timespec now;
    XDR xdrs;
    int stat;

    assert(auth != NULL);

    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)clock_gettime(CLOCK_MONOTONIC_FAST, &now);
    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;

    assert(auth != NULL);

    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(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;

    assert(auth != NULL);

    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))))
        __warnx(TIRPC_DEBUG_FLAG_AUTH, "auth_none.c - Fatal marshalling "
                "problem");
    else
        au->au_mpos = XDR_GETPOS(xdrs);
    XDR_DESTROY(xdrs);
}

static bool
authunix_wrap(AUTH *auth, XDR *xdrs, xdrproc_t xfunc, caddr_t xwhere)
{
    return ((*xfunc)(xdrs, xwhere));
}

static struct auth_ops *
authunix_ops(void)
{
    static struct auth_ops ops;
    extern mutex_t ops_lock;

    /* VARIABLES PROTECTED BY ops_lock: ops */

    mutex_lock(&ops_lock);
    if (ops.ah_nextverf == NULL) {
        ops.ah_nextverf = authunix_nextverf;
        ops.ah_marshal = authunix_marshal;
        ops.ah_validate = authunix_validate;
        ops.ah_refresh = authunix_refresh;
        ops.ah_destroy = authunix_destroy;
        ops.ah_wrap = authunix_wrap;
        ops.ah_unwrap = authunix_wrap;
    }
    mutex_unlock(&ops_lock);
    return (&ops);
}