libnsl/key/publickey.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
/*
 * Copyright 2014 Nexenta Systems, Inc.  All rights reserved.
 */

/* Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */
/* All Rights Reserved */

/*
 * Portions of this source code were derived from Berkeley 4.3 BSD
 * under license from the Regents of the University of California.
 */

/*
 * publickey.c
 *
 *
 * Public and Private (secret) key lookup routines. These functions
 * are used by the secure RPC auth_des flavor to get the public and
 * private keys for secure RPC principals. Originally designed to
 * talk only to YP, AT&T modified them to talk to files, and now
 * they can also talk to NIS+. The policy for these lookups is now
 * defined in terms of the nameservice switch as follows :
 *  publickey: nis files
 *
 */
#include "mt.h"
#include "../rpc/rpc_mt.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <assert.h>
#include <sys/types.h>
#include <pwd.h>
#include "nsswitch.h"
#include <rpc/rpc.h>
#include <rpc/key_prot.h>
#include <rpcsvc/nis.h>
#include <rpcsvc/ypclnt.h>
#include <rpcsvc/nis_dhext.h>
#include <thread.h>
#include "../nis/gen/nis_clnt.h"
#include <nss_dbdefs.h>


static const char *PKMAP = "publickey.byname";
static const char *PKFILE = "/etc/publickey";
static const char dh_caps_str[] = "DH";
static const char des_caps_str[] = AUTH_DES_AUTH_TYPE;

static char *netname2hashname(const char *, char *, int, keylen_t,
                algtype_t);

#define WORKBUFSIZE 1024

extern int xdecrypt();

extern int __yp_match_cflookup(char *, char *, char *, int, char **,
            int *, int *);


/*
 * default publickey policy:
 *  publickey: nis [NOTFOUND = return] files
 */


/*  NSW_NOTSUCCESS  NSW_NOTFOUND   NSW_UNAVAIL    NSW_TRYAGAIN */
#define DEF_ACTION {__NSW_RETURN, __NSW_RETURN, __NSW_CONTINUE, __NSW_CONTINUE}

static struct __nsw_lookup lookup_files = {"files", DEF_ACTION, NULL, NULL},
        lookup_nis = {"nis", DEF_ACTION, NULL, &lookup_files};
static struct __nsw_switchconfig publickey_default =
            {0, "publickey", 2, &lookup_nis};

#ifndef NUL
#define NUL '\0'
#endif

extern mutex_t serialize_pkey;

static int extract_secret();

/*
 * db_root is used for switch backends.
 */
static DEFINE_NSS_DB_ROOT(db_root);

/*
 * str2key
 */
/* ARGSUSED */
static int
str2key(const char *instr, int lenstr,
            void *ent, char *buffer, int buflen) {
    if (lenstr + 1 > buflen)
        return (NSS_STR_PARSE_ERANGE);
    /*
     * We copy the input string into the output buffer
     */
    (void) memcpy(buffer, instr, lenstr);
    buffer[lenstr] = '\0';

    return (NSS_STR_PARSE_SUCCESS);
}
/*
 * These functions are the "backends" for the switch for public keys. They
 * get both the public and private keys from each of the supported name
 * services (nis, files). They are passed the appropriate parameters
 * and return 0 if unsuccessful with *errp set, or 1 when they got just the
 * public key and 3 when they got both the public and private keys.
 *
 *
 * getkey_nis()
 *
 * Internal implementation of getpublickey() using NIS (aka Yellow Pages,
 * aka YP).
 *
 * NOTE : *** this function returns nsswitch codes and _not_ the
 * value returned by getpublickey.
 */
static int
getkeys_nis(int *errp, char *netname, char *pkey, char *skey, char *passwd)
{
    char    *domain;
    char    *keyval = NULL;
    int keylen, err, r = 0;
    char    *p;
    int len;

    p = strchr(netname, '@');
    if (!p) {
        *errp = __NSW_UNAVAIL;
        return (0);
    }

    domain = ++p;


    /*
     * Instead of calling yp_match(), we use __yp_match_cflookup() here
     * which has time-out control for the binding operation to nis
     * servers.
     */
    err = __yp_match_cflookup(domain, (char *)PKMAP, netname,
        strlen(netname), &keyval, &keylen, 0);

    switch (err) {
    case YPERR_KEY :
        if (keyval)
            free(keyval);
        *errp = __NSW_NOTFOUND;
        return (0);
    default :
        if (keyval)
            free(keyval);
        *errp = __NSW_UNAVAIL;
        return (0);
    case 0:
        break;
    }

    p = strchr(keyval, ':');
    if (p == NULL) {
        free(keyval);
        *errp = __NSW_NOTFOUND;
        return (0);
    }
    *p = 0;
    if (pkey) {
        len = strlen(keyval);
        if (len > HEXKEYBYTES) {
            free(keyval);
            *errp = __NSW_NOTFOUND;
            return (0);
        }
        (void) strcpy(pkey, keyval);
    }
    r = 1;
    p++;
    if (skey && extract_secret(p, skey, passwd))
        r |= 2;
    free(keyval);
    *errp = __NSW_SUCCESS;
    return (r);
}

/*
 * getkey_files()
 *
 * The files version of getpublickey. This function attempts to
 * get the publickey from the file PKFILE .
 *
 * This function defines the format of the /etc/publickey file to
 * be :
 *  netname <whitespace> publickey:privatekey
 *
 * NOTE : *** this function returns nsswitch codes and _not_ the
 * value returned by getpublickey.
 */

static int
getkeys_files(int *errp, char *netname, char *pkey, char *skey, char *passwd)
{
    char *mkey;
    char *mval;
    char buf[WORKBUFSIZE];
    int r = 0;
    char *res;
    FILE *fd;
    char *p;
    char *lasts;

    fd = fopen(PKFILE, "rF");
    if (fd == NULL) {
        *errp = __NSW_UNAVAIL;
        return (0);
    }

    /* Search through the file linearly :-( */
    while ((res = fgets(buf, WORKBUFSIZE, fd)) != NULL) {

        if ((res[0] == '#') || (res[0] == '\n'))
            continue;
        else {
            mkey = strtok_r(buf, "\t ", &lasts);
            if (mkey == NULL) {
                syslog(LOG_INFO,
                "getpublickey: Bad record in %s for %s",
                    PKFILE, netname);
                continue;
            }
            mval = strtok_r(NULL, " \t#\n", &lasts);
            if (mval == NULL) {
                syslog(LOG_INFO,
                "getpublickey: Bad record in %s for %s",
                    PKFILE, netname);
                continue;
            }
            /* NOTE : Case insensitive compare. */
            if (strcasecmp(mkey, netname) == 0) {
                p = strchr(mval, ':');
                if (p == NULL) {
                    syslog(LOG_INFO,
                "getpublickey: Bad record in %s for %s",
                        PKFILE, netname);
                    continue;
                }

                *p = 0;
                if (pkey) {
                    int len = strlen(mval);

                    if (len > HEXKEYBYTES) {
                        syslog(LOG_INFO,
                "getpublickey: Bad record in %s for %s",
                            PKFILE, netname);
                        continue;
                    }
                    (void) strcpy(pkey, mval);
                }
                r = 1;
                p++;
                if (skey && extract_secret(p, skey, passwd))
                    r |= 2;
                (void) fclose(fd);
                *errp = __NSW_SUCCESS;
                return (r);
            }
        }
    }

    (void) fclose(fd);
    *errp = __NSW_NOTFOUND;
    return (0);
}

/*
 * getpublickey(netname, key)
 *
 * This is the actual exported interface for this function.
 */

int
__getpublickey_cached(char *netname, char *pkey, int *from_cache)
{
    return (__getpublickey_cached_g(netname, KEYSIZE, 0, pkey,
        HEXKEYBYTES+1, from_cache));
}

int
getpublickey(const char *netname, char *pkey)
{
    return (__getpublickey_cached((char *)netname, pkey, (int *)0));
}

void
__getpublickey_flush(const char *netname)
{
    __getpublickey_flush_g(netname, 192, 0);
}

int
getsecretkey(const char *netname, char *skey, const char *passwd)
{
    return (getsecretkey_g(netname, KEYSIZE, 0, skey, HEXKEYBYTES+1,
        passwd));
}

/*
 *  Routines to cache publickeys.
 */


/*
 * Generic DH (any size keys) version of extract_secret.
 */
static int
extract_secret_g(
    char        *raw,       /* in  */
    char        *private,   /* out */
    int     prilen,     /* in  */
    char        *passwd,    /* in  */
    char        *netname,   /* in  */
    keylen_t    keylen,     /* in  */
    algtype_t   algtype)    /* in  */

{
    char    *buf = malloc(strlen(raw) + 1); /* private tmp buf */
    char    *p;

    if (!buf || !passwd || !raw || !private || !prilen ||
            !VALID_KEYALG(keylen, algtype)) {
        if (private)
            *private = NUL;
        if (buf)
            free(buf);
        return (0);
    }

    (void) strcpy(buf, raw);

    /* strip off pesky colon if it exists */
    p = strchr(buf, ':');
    if (p) {
        *p = 0;
    }

    /* raw buf has chksum appended, so let's verify it too */
    if (!xdecrypt_g(buf, keylen, algtype, passwd, netname, TRUE)) {
        private[0] = 0;
        free(buf);
        return (1); /* yes, return 1 even if xdecrypt fails */
    }

    if (strlen(buf) >= prilen) {
        private[0] = 0;
        free(buf);
        return (0);
    }

    (void) strcpy(private, buf);
    free(buf);
    return (1);
}

/*
 * extract_secret()
 *
 * This generic function will extract the private key
 * from a string using the given password. Note that
 * it uses the DES based function xdecrypt()
 */
static int
extract_secret(char *raw, char *private, char *passwd)
{
    return (extract_secret_g(raw, private, HEXKEYBYTES+1, passwd,
        NULL, KEYSIZE, 0));
}

/*
 * getkeys_ldap_g()
 *
 * Fetches the key pair from LDAP.  This version handles any size
 * DH keys.
 */

void
_nss_initf_publickey(nss_db_params_t *p)
{
    p->name = NSS_DBNAM_PUBLICKEY;
    p->default_config = NSS_DEFCONF_PUBLICKEY;
}


static int
getkeys_ldap_g(
    int     *err,       /* in  */
    char        *netname,   /* in  */
    char        *pkey,      /* out */
    int     pkeylen,    /* in  */
    char        *skey,      /* out */
    int     skeylen,    /* in  */
    char        *passwd,    /* in  */
    keylen_t    keylen,     /* in  */
    algtype_t   algtype)    /* in  */
{
    int     r = 0;
    char        *p;
    char        keytypename[NIS_MAXNAMELEN+1];
    int     len;
    const bool_t    classic_des = AUTH_DES_KEY(keylen, algtype);
    int     rc = 0;
    nss_XbyY_args_t arg;
    nss_XbyY_buf_t  *buf = NULL;
    char        *keyval;

    NSS_XbyY_ALLOC(&buf, 0, NSS_BUFLEN_PUBLICKEY);

    NSS_XbyY_INIT(&arg, buf->result, buf->buffer, buf->buflen, str2key);
    arg.key.pkey.name = netname;

    /*
     * LDAP stores the public and secret key info in entries using
     * nisKeyObject objectclass.  Each key is tagged with the
     * keytype, keylength, and algorithm.  The tag has the following
     * format: {<keytype><keylength>-<algorithm>}.  For example,
     * {DH192-0}.
     */
    if (classic_des)
        (void) strcpy(keytypename, "{DH192-0}");
    else
        (void) sprintf(keytypename, "{%s%d-%d}",
            dh_caps_str, keylen, algtype);
    arg.key.pkey.keytype = keytypename;

    if (nss_search(&db_root, _nss_initf_publickey, NSS_DBOP_KEYS_BYNAME,
        &arg) != NSS_SUCCESS) {
        NSS_XbyY_FREE(&buf);
        *err = __NSW_NOTFOUND;
        return (0);
    }
    keyval = buf->buffer;
    p = strchr(keyval, ':');
    if (p == NULL) {
        NSS_XbyY_FREE(&buf);
        *err = __NSW_NOTFOUND;
        return (0);
    }
    *p = 0;
    if (pkey) {
        len = strlen(keyval);
        if (len > HEXKEYBYTES) {
            NSS_XbyY_FREE(&buf);
            *err = __NSW_NOTFOUND;
            return (0);
        }
        (void) strcpy(pkey, keyval);
    }
    r = 1;
    p++;
    if (skey && extract_secret(p, skey, passwd))
        r |= 2;
    NSS_XbyY_FREE(&buf);
    *err = __NSW_SUCCESS;
    return (r);
}


/*
 * Convert a netname to a name we will hash on.  For classic_des,
 * just copy netname as is.  But for new and improved ("now in
 * new longer sizes!") DHEXT, add a ":keylen-algtype" suffix to hash on.
 *
 * Returns the hashname string on success or NULL on failure.
 */
static char *
netname2hashname(
    const char *netname,
    char *hashname,
    int bufsiz,
    keylen_t keylen,
    algtype_t algtype)
{
    const bool_t classic_des = AUTH_DES_KEY(keylen, algtype);

    if (!netname || !hashname || !bufsiz)
        return (NULL);

    if (classic_des) {
        if (bufsiz > strlen(netname))
            (void) strcpy(hashname, netname);
        else
            return (NULL);
    } else {
        char tmp[128];
        (void) sprintf(tmp, ":%d-%d", keylen, algtype);
        if (bufsiz > (strlen(netname) + strlen(tmp)))
            (void) sprintf(hashname, "%s%s", netname, tmp);
        else
            return (NULL);
    }

    return (hashname);
}

/*
 * Flush netname's publickey of the given key length and algorithm type.
 */
void
__getpublickey_flush_g(const char *netname, keylen_t keylen, algtype_t algtype)
{
    char    *p, hashname[MAXNETNAMELEN+1];
    p = netname2hashname(netname, hashname, MAXNETNAMELEN, keylen, algtype);
}

/*
 * Generic DH (any size keys) version of __getpublickey_cached.
 */
int
__getpublickey_cached_g(const char netname[],   /* in  */
            keylen_t keylen,    /* in  */
            algtype_t algtype,  /* in  */
            char *pkey,     /* out */
            size_t pkeylen,     /* in  */
            int *from_cache)    /* in/out  */
{
    int needfree = 1, res, err;
    struct __nsw_switchconfig *conf;
    struct __nsw_lookup *look;
    enum __nsw_parse_err perr;
    const bool_t classic_des = AUTH_DES_KEY(keylen, algtype);
    int retry_cache = 0;

    if (!netname || !pkey)
        return (0);

    conf = __nsw_getconfig("publickey", &perr);
    if (!conf) {
        conf = &publickey_default;
        needfree = 0;
    }
    for (look = conf->lookups; look; look = look->next) {
        if (strcmp(look->service_name, "ldap") == 0) {
            res = getkeys_ldap_g(&err, (char *)netname,
                pkey, pkeylen, NULL, 0, NULL,
                keylen, algtype);
        /* long DH keys will not be in nis or files */
        } else if (classic_des &&
            strcmp(look->service_name, "nis") == 0)
            res = getkeys_nis(&err, (char *)netname, pkey,
                NULL, NULL);
        else if (classic_des &&
            strcmp(look->service_name, "files") == 0)
            res = getkeys_files(&err, (char *)netname, pkey,
                NULL, NULL);
        else {
            syslog(LOG_INFO, "Unknown publickey nameservice '%s'",
                look->service_name);
            err = __NSW_UNAVAIL;
            res = 0;
        }

        switch (look->actions[err]) {
        case __NSW_CONTINUE :
            continue;
        case __NSW_RETURN :
            if (needfree)
                __nsw_freeconfig(conf);
            return ((res & 1) != 0);
        default :
            syslog(LOG_INFO, "Unknown action for nameservice %s",
                look->service_name);
        }
    }

    if (needfree)
        __nsw_freeconfig(conf);
    return (0);
}


/*
 * Generic (all sizes) DH version of getpublickey.
 */
int
getpublickey_g(
    const char *netname,    /* in  */
    int keylen,     /* in  */
    int algtype,        /* in  */
    char *pkey,     /* out  */
    size_t pkeylen)     /* in  */
{
    return (__getpublickey_cached_g(netname, keylen, algtype, pkey,
        pkeylen, (int *)0));
}

/*
 * Generic (all sizes) DH version of getsecretkey_g.
 */
int
getsecretkey_g(
    const char  *netname,   /* in  */
    keylen_t    keylen,     /* in  */
    algtype_t   algtype,    /* in  */
    char        *skey,      /* out */
    size_t      skeylen,    /* in  */
    const char  *passwd)    /* in  */
{
    int needfree = 1, res, err;
    struct __nsw_switchconfig *conf;
    struct __nsw_lookup *look;
    enum __nsw_parse_err perr;
    const bool_t classic_des = AUTH_DES_KEY(keylen, algtype);

    if (!netname || !skey || !skeylen)
        return (0);

    conf = __nsw_getconfig("publickey", &perr);

    if (!conf) {
        conf = &publickey_default;
        needfree = 0;
    }

    for (look = conf->lookups; look; look = look->next) {
        if (strcmp(look->service_name, "ldap") == 0)
            res = getkeys_ldap_g(&err, (char *)netname,
                NULL, 0, skey, skeylen,
                (char *)passwd, keylen, algtype);
        /* long DH keys will not be in nis or files */
        else if (classic_des && strcmp(look->service_name, "nis") == 0)
            res = getkeys_nis(&err, (char *)netname,
                NULL, skey, (char *)passwd);
        else if (classic_des &&
            strcmp(look->service_name, "files") == 0)
            res = getkeys_files(&err, (char *)netname,
                NULL, skey, (char *)passwd);
        else {
            syslog(LOG_INFO, "Unknown publickey nameservice '%s'",
                look->service_name);
            err = __NSW_UNAVAIL;
            res = 0;
        }
        switch (look->actions[err]) {
        case __NSW_CONTINUE :
            continue;
        case __NSW_RETURN :
            if (needfree)
                __nsw_freeconfig(conf);
            return ((res & 2) != 0);
        default :
            syslog(LOG_INFO, "Unknown action for nameservice %s",
                look->service_name);
        }
    }
    if (needfree)
        __nsw_freeconfig(conf);
    return (0);
}