libsmb/common/smb_pwdutil.c

	smb_pwdutil.c revision 9fb67ea305c66b6a297583b9b0db6796b0dfe497
/*
 * 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 2010 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <syslog.h>
#include <stdlib.h>
#include <unistd.h>
#include <limits.h>
#include <strings.h>
#include <synch.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/avl.h>
#include <fcntl.h>
#include <thread.h>
#include <pwd.h>
#include <dlfcn.h>
#include <link.h>
#include <assert.h>
#include <smbsrv/libsmb.h>

#define SMB_PASSWD  "/var/smb/smbpasswd"
#define SMB_OPASSWD "/var/smb/osmbpasswd"
#define SMB_PASSTEMP    "/var/smb/ptmp"
#define SMB_PASSLCK "/var/smb/.pwd.lock"

#define SMB_PWD_DISABLE "*DIS*"
#define SMB_PWD_BUFSIZE 256

#define S_WAITTIME  15

typedef enum {
    SMB_PWD_NAME = 0,
    SMB_PWD_UID,
    SMB_PWD_LMHASH,
    SMB_PWD_NTHASH,
    SMB_PWD_NARG
} smb_pwdarg_t;

static struct flock flock = { 0, 0, 0, 0, 0, 0 };
static pid_t lck_pid = 0;   /* process's pid at last lock */
static thread_t lck_tid = 0;    /* thread that holds the lock */
static int fildes = -1;
static mutex_t lck_lock = DEFAULTMUTEX;
static void *smb_pwd_hdl = NULL;

static struct {
    smb_passwd_t *(*pwop_getpwnam)(const char *, smb_passwd_t *);
    smb_passwd_t *(*pwop_getpwuid)(uid_t, smb_passwd_t *);
    int (*pwop_setcntl)(const char *, int);
    int (*pwop_setpasswd)(const char *, const char *);
    int (*pwop_num)(void);
    int (*pwop_iteropen)(smb_pwditer_t *);
    smb_luser_t *(*pwop_iterate)(smb_pwditer_t *);
    void (*pwop_iterclose)(smb_pwditer_t *);
} smb_pwd_ops;

static int smb_pwd_lock(void);
static int smb_pwd_unlock(void);
static int smb_pwd_flck(void);
static int smb_pwd_fulck(void);

/*
 * buffer structure used by smb_pwd_fgetent/smb_pwd_fputent
 */
typedef struct smb_pwbuf {
    char        pw_buf[SMB_PWD_BUFSIZE];
    smb_passwd_t    *pw_pwd;
} smb_pwbuf_t;

/*
 * flag values used with smb_pwd_fgetent
 */
#define SMB_PWD_GETF_ALL    1   /* get all the account info */
#define SMB_PWD_GETF_NOPWD  2   /* password is not needed */

static smb_pwbuf_t *smb_pwd_fgetent(FILE *, smb_pwbuf_t *, uint32_t);
static int smb_pwd_fputent(FILE *, const smb_pwbuf_t *);
static int smb_pwd_chgpwent(smb_passwd_t *, const char *, int);
static int smb_pwd_update(const char *, const char *, int);

/*
 * Local Users Cache
 *
 * Simplifying assumptions
 *
 *  o smbpasswd is a service private file and shouldn't be edited manually
 *  o accounts are only added/modified via passwd and/or smbadm CLIs
 *  o accounts are not removed but disabled using smbadm CLI
 *  o editing smbpasswd manually might result in cache inconsistency
 *
 * Cache is created and populated upon service startup.
 * Cache is updated each time users list is requested if there's been
 * any change in smbpasswd file. The change criteria is smbpasswd's
 * modification timestamp.
 */

/*
 * User cache handle
 */
typedef struct smb_uchandle {
    avl_tree_t  uc_cache;
    rwlock_t    uc_cache_lck;
    timestruc_t uc_timestamp;
    uint32_t    uc_refcnt;
    uint32_t    uc_state;
    mutex_t     uc_mtx;
    cond_t      uc_cv;
} smb_uchandle_t;

#define SMB_UCHS_NOCACHE    0
#define SMB_UCHS_CREATED    1
#define SMB_UCHS_UPDATING   2
#define SMB_UCHS_UPDATED    3
#define SMB_UCHS_DESTROYING 4

/*
 * User cache node
 */
typedef struct smb_ucnode {
    smb_luser_t cn_user;
    avl_node_t  cn_link;
} smb_ucnode_t;

static void smb_lucache_create(void);
static void smb_lucache_destroy(void);
static void smb_lucache_update(void);
static int smb_lucache_num(void);
static int smb_lucache_lock(void);
static void smb_lucache_unlock(void);
static int smb_lucache_do_update(void);
static void smb_lucache_flush(void);

static smb_uchandle_t smb_uch;

/*
 * smb_pwd_init
 *
 * Initializes the cache if requested.
 * Checks to see if a password management utility library
 * is interposed. If yes then it'll initializes smb_pwd_ops
 * structure with function pointers from this library.
 */
void
smb_pwd_init(boolean_t create_cache)
{
    if (create_cache) {
        smb_lucache_create();
#if 0
        /*
         * This pre-loading of the cache results in idmapd requests.
         * With the change to allow idmapd to call into libsmb to
         * map names and SIDs, this creates a circular startup
         * dependency.  This call has been temporarily disabled to
         * avoid this issue.  It can be enabled when the name/SID
         * lookup can be done directly on the LSA service.
         */
        smb_lucache_update();
#endif
    }

    smb_pwd_hdl = smb_dlopen();
    if (smb_pwd_hdl == NULL)
        return;

    bzero((void *)&smb_pwd_ops, sizeof (smb_pwd_ops));

    smb_pwd_ops.pwop_getpwnam =
        (smb_passwd_t *(*)())dlsym(smb_pwd_hdl, "smb_pwd_getpwnam");

    smb_pwd_ops.pwop_getpwuid =
        (smb_passwd_t *(*)())dlsym(smb_pwd_hdl, "smb_pwd_getpwuid");

    smb_pwd_ops.pwop_setcntl =
        (int (*)())dlsym(smb_pwd_hdl, "smb_pwd_setcntl");

    smb_pwd_ops.pwop_setpasswd =
        (int (*)())dlsym(smb_pwd_hdl, "smb_pwd_setpasswd");

    smb_pwd_ops.pwop_num =
        (int (*)())dlsym(smb_pwd_hdl, "smb_pwd_num");

    smb_pwd_ops.pwop_iteropen =
        (int (*)())dlsym(smb_pwd_hdl, "smb_pwd_iteropen");

    smb_pwd_ops.pwop_iterclose =
        (void (*)())dlsym(smb_pwd_hdl, "smb_pwd_iterclose");

    smb_pwd_ops.pwop_iterate =
        (smb_luser_t *(*)())dlsym(smb_pwd_hdl, "smb_pwd_iterate");

    if (smb_pwd_ops.pwop_getpwnam == NULL ||
        smb_pwd_ops.pwop_getpwuid == NULL ||
        smb_pwd_ops.pwop_setcntl == NULL ||
        smb_pwd_ops.pwop_setpasswd == NULL ||
        smb_pwd_ops.pwop_num == NULL ||
        smb_pwd_ops.pwop_iteropen == NULL ||
        smb_pwd_ops.pwop_iterclose == NULL ||
        smb_pwd_ops.pwop_iterate == NULL) {
        smb_dlclose(smb_pwd_hdl);
        smb_pwd_hdl = NULL;

        /* If error or function(s) are missing, use original lib */
        bzero((void *)&smb_pwd_ops, sizeof (smb_pwd_ops));
    }
}

/*
 * smb_pwd_fini
 *
 * Destroys the cache.
 * Closes interposed library.
 */
void
smb_pwd_fini(void)
{
    smb_lucache_destroy();
    smb_dlclose(smb_pwd_hdl);
    smb_pwd_hdl = NULL;
    bzero((void *)&smb_pwd_ops, sizeof (smb_pwd_ops));
}

/*
 * smb_pwd_getpwnam
 *
 * Returns a smb password structure for the given user name.
 * smbpw is a pointer to a buffer allocated by the caller.
 *
 * Returns NULL upon failure.
 */
smb_passwd_t *
smb_pwd_getpwnam(const char *name, smb_passwd_t *smbpw)
{
    boolean_t found = B_FALSE;
    smb_pwbuf_t pwbuf;
    FILE *fp;
    int err;

    if (smb_pwd_ops.pwop_getpwnam != NULL)
        return (smb_pwd_ops.pwop_getpwnam(name, smbpw));

    err = smb_pwd_lock();
    if (err != SMB_PWE_SUCCESS)
        return (NULL);

    if ((fp = fopen(SMB_PASSWD, "rF")) == NULL) {
        (void) smb_pwd_unlock();
        return (NULL);
    }

    pwbuf.pw_pwd = smbpw;

    while (smb_pwd_fgetent(fp, &pwbuf, SMB_PWD_GETF_ALL) != NULL) {
        if (strcmp(name, smbpw->pw_name) == 0) {
            if ((smbpw->pw_flags & (SMB_PWF_LM | SMB_PWF_NT)))
                found = B_TRUE;
            break;
        }
    }

    (void) fclose(fp);
    (void) smb_pwd_unlock();

    if (!found) {
        bzero(smbpw, sizeof (smb_passwd_t));
        return (NULL);
    }

    return (smbpw);
}

/*
 * smb_pwd_getpwuid
 *
 * Returns a smb password structure for the given UID
 * smbpw is a pointer to a buffer allocated by the caller.
 *
 * Returns NULL upon failure.
 */
smb_passwd_t *
smb_pwd_getpwuid(uid_t uid, smb_passwd_t *smbpw)
{
    boolean_t found = B_FALSE;
    smb_pwbuf_t pwbuf;
    FILE *fp;
    int err;

    if (smb_pwd_ops.pwop_getpwuid != NULL)
        return (smb_pwd_ops.pwop_getpwuid(uid, smbpw));

    err = smb_pwd_lock();
    if (err != SMB_PWE_SUCCESS)
        return (NULL);

    if ((fp = fopen(SMB_PASSWD, "rF")) == NULL) {
        (void) smb_pwd_unlock();
        return (NULL);
    }

    pwbuf.pw_pwd = smbpw;

    while (smb_pwd_fgetent(fp, &pwbuf, SMB_PWD_GETF_ALL) != NULL) {
        if (uid == smbpw->pw_uid) {
            if ((smbpw->pw_flags & (SMB_PWF_LM | SMB_PWF_NT)))
                found = B_TRUE;
            break;
        }
    }

    (void) fclose(fp);
    (void) smb_pwd_unlock();

    if (!found) {
        bzero(smbpw, sizeof (smb_passwd_t));
        return (NULL);
    }

    return (smbpw);
}

/*
 * smb_pwd_setpasswd
 *
 * Update/add the given user to the smbpasswd file.
 */
int
smb_pwd_setpasswd(const char *name, const char *password)
{
    if (smb_pwd_ops.pwop_setpasswd != NULL)
        return (smb_pwd_ops.pwop_setpasswd(name, password));

    return (smb_pwd_update(name, password, 0));
}

/*
 * smb_pwd_setcntl
 *
 * Change the account state. This can be making the account
 * disable/enable or removing its LM hash.
 */
int
smb_pwd_setcntl(const char *name, int control)
{
    if (smb_pwd_ops.pwop_setcntl != NULL)
        return (smb_pwd_ops.pwop_setcntl(name, control));

    if (control == 0)
        return (SMB_PWE_SUCCESS);

    return (smb_pwd_update(name, NULL, control));
}

/*
 * smb_pwd_num
 *
 * Returns the number of cached local users
 */
int
smb_pwd_num(void)
{
    if (smb_pwd_ops.pwop_num != NULL)
        return (smb_pwd_ops.pwop_num());

    smb_lucache_update();

    return (smb_lucache_num());
}

/*
 * smb_pwd_iteropen
 *
 * Initalizes the given iterator handle.
 * This handle will be used to iterate the users cache
 * by the caller. The cache will be locked for read and it
 * will remain locked until smb_pwd_iterclose() is called.
 */
int
smb_pwd_iteropen(smb_pwditer_t *iter)
{
    if (iter == NULL)
        return (SMB_PWE_INVALID_PARAM);

    if (smb_pwd_ops.pwop_iteropen != NULL)
        return (smb_pwd_ops.pwop_iteropen(iter));

    iter->spi_next = NULL;

    smb_lucache_update();

    return (smb_lucache_lock());
}

/*
 * smb_pwd_iterate
 *
 * Scans through users cache using the given iterator
 */
smb_luser_t *
smb_pwd_iterate(smb_pwditer_t *iter)
{
    smb_ucnode_t *ucnode;

    if (iter == NULL)
        return (NULL);

    if (smb_pwd_ops.pwop_iterate != NULL)
        return (smb_pwd_ops.pwop_iterate(iter));

    if (iter->spi_next == NULL)
        ucnode = avl_first(&smb_uch.uc_cache);
    else
        ucnode = AVL_NEXT(&smb_uch.uc_cache, iter->spi_next);

    if ((iter->spi_next = ucnode) != NULL)
        return (&ucnode->cn_user);

    return (NULL);
}

/*
 * smb_pwd_iterclose
 *
 * Closes the given iterator. Effectively it only unlocks the cache
 */
void
smb_pwd_iterclose(smb_pwditer_t *iter)
{
    if (smb_pwd_ops.pwop_iterclose != NULL) {
        smb_pwd_ops.pwop_iterclose(iter);
        return;
    }

    if (iter != NULL)
        smb_lucache_unlock();
}

/*
 * smb_pwd_update
 *
 * Updates the password entry of the given user if the user already
 * has an entry, otherwise it'll add an entry for the user with
 * given password and control information.
 */
static int
smb_pwd_update(const char *name, const char *password, int control)
{
    struct stat64 stbuf;
    FILE *src, *dst;
    int tempfd;
    int err = SMB_PWE_SUCCESS;
    smb_pwbuf_t pwbuf;
    smb_passwd_t smbpw;
    boolean_t newent = B_TRUE;
    boolean_t user_disable = B_FALSE;
    char uxbuf[1024];
    struct passwd uxpw;
    int64_t lm_level;

    err = smb_pwd_lock();
    if (err != SMB_PWE_SUCCESS)
        return (err);

    if (stat64(SMB_PASSWD, &stbuf) < 0) {
        err = SMB_PWE_STAT_FAILED;
        goto passwd_exit;
    }

    if ((tempfd = open(SMB_PASSTEMP, O_WRONLY|O_CREAT|O_TRUNC, 0600)) < 0) {
        err = SMB_PWE_OPEN_FAILED;
        goto passwd_exit;
    }

    if ((dst = fdopen(tempfd, "wF")) == NULL) {
        err = SMB_PWE_OPEN_FAILED;
        goto passwd_exit;
    }

    if ((src = fopen(SMB_PASSWD, "rF")) == NULL) {
        err = SMB_PWE_OPEN_FAILED;
        (void) fclose(dst);
        (void) unlink(SMB_PASSTEMP);
        goto passwd_exit;
    }

    if (smb_config_getnum(SMB_CI_LM_LEVEL, &lm_level) != SMBD_SMF_OK)
        lm_level = 4;

    if (lm_level >= 4)
        control |= SMB_PWC_NOLM;

    pwbuf.pw_pwd = &smbpw;

    /*
     * copy old password entries to temporary file while replacing
     * the entry that matches "name"
     */
    while (smb_pwd_fgetent(src, &pwbuf, SMB_PWD_GETF_ALL) != NULL) {
        if (strcmp(smbpw.pw_name, name) == 0) {
            err = smb_pwd_chgpwent(&smbpw, password, control);
            if (err == SMB_PWE_USER_DISABLE)
                user_disable = B_TRUE;
            err = smb_pwd_fputent(dst, &pwbuf);
            newent = B_FALSE;
        } else {
            err = smb_pwd_fputent(dst, &pwbuf);
        }

        if (err != SMB_PWE_SUCCESS) {
            (void) fclose(src);
            (void) fclose(dst);
            goto passwd_exit;
        }
    }

    if (newent) {
        if (getpwnam_r(name, &uxpw, uxbuf, sizeof (uxbuf))) {
            bzero(&smbpw, sizeof (smb_passwd_t));
            (void) strlcpy(smbpw.pw_name, uxpw.pw_name,
                sizeof (smbpw.pw_name));
            smbpw.pw_uid = uxpw.pw_uid;
            (void) smb_pwd_chgpwent(&smbpw, password, control);
            err = smb_pwd_fputent(dst, &pwbuf);
        } else {
            err = SMB_PWE_USER_UNKNOWN;
        }

        if (err != SMB_PWE_SUCCESS) {
            (void) fclose(src);
            (void) fclose(dst);
            goto passwd_exit;
        }
    }

    (void) fclose(src);
    if (fclose(dst) != 0) {
        err = SMB_PWE_CLOSE_FAILED;
        goto passwd_exit; /* Don't trust the temporary file */
    }

    /* Rename temp to passwd */
    if (unlink(SMB_OPASSWD) && access(SMB_OPASSWD, 0) == 0) {
        err = SMB_PWE_UPDATE_FAILED;
        (void) unlink(SMB_PASSTEMP);
        goto passwd_exit;
    }

    if (link(SMB_PASSWD, SMB_OPASSWD) == -1) {
        err = SMB_PWE_UPDATE_FAILED;
        (void) unlink(SMB_PASSTEMP);
        goto passwd_exit;
    }

    if (rename(SMB_PASSTEMP, SMB_PASSWD) == -1) {
        err = SMB_PWE_UPDATE_FAILED;
        (void) unlink(SMB_PASSTEMP);
        goto passwd_exit;
    }

    (void) chmod(SMB_PASSWD, 0400);

passwd_exit:
    (void) smb_pwd_unlock();
    if ((err == SMB_PWE_SUCCESS) && user_disable)
        err = SMB_PWE_USER_DISABLE;

    return (err);
}

/*
 * smb_pwd_fgetent
 *
 * Parse the buffer in the passed pwbuf and fill in the
 * smb password structure to point to the parsed information.
 * The entry format is:
 *
 *  <user-name>:<user-id>:<LM hash>:<NTLM hash>
 *
 * Returns a pointer to the passed pwbuf structure on success,
 * otherwise returns NULL.
 */
static smb_pwbuf_t *
smb_pwd_fgetent(FILE *fp, smb_pwbuf_t *pwbuf, uint32_t flags)
{
    char *argv[SMB_PWD_NARG];
    char *pwentry;
    smb_passwd_t *pw;
    smb_pwdarg_t i;
    int lm_len, nt_len;

    pwentry = pwbuf->pw_buf;
    if (fgets(pwentry, SMB_PWD_BUFSIZE, fp) == NULL)
        return (NULL);
    (void) trim_whitespace(pwentry);

    for (i = 0; i < SMB_PWD_NARG; ++i) {
        if ((argv[i] = strsep((char **)&pwentry, ":")) == NULL)
            return (NULL);
    }

    if ((*argv[SMB_PWD_NAME] == '\0') || (*argv[SMB_PWD_UID] == '\0'))
        return (NULL);

    pw = pwbuf->pw_pwd;
    bzero(pw, sizeof (smb_passwd_t));
    pw->pw_uid = strtoul(argv[SMB_PWD_UID], 0, 10);
    (void) strlcpy(pw->pw_name, argv[SMB_PWD_NAME], sizeof (pw->pw_name));

    if (strcmp(argv[SMB_PWD_LMHASH], SMB_PWD_DISABLE) == 0) {
        pw->pw_flags |= SMB_PWF_DISABLE;
        if (flags != SMB_PWD_GETF_NOPWD) {
            (void) strcpy((char *)pw->pw_lmhash, SMB_PWD_DISABLE);
            (void) strcpy((char *)pw->pw_nthash, SMB_PWD_DISABLE);
        }
        return (pwbuf);
    }

    if (flags == SMB_PWD_GETF_NOPWD)
        return (pwbuf);

    lm_len = strlen(argv[SMB_PWD_LMHASH]);
    if (lm_len == SMBAUTH_HEXHASH_SZ) {
        (void) hextobin(argv[SMB_PWD_LMHASH], SMBAUTH_HEXHASH_SZ,
            (char *)pw->pw_lmhash, SMBAUTH_HASH_SZ);

        pw->pw_flags |= SMB_PWF_LM;
    } else if (lm_len != 0) {
        return (NULL);
    }

    nt_len = strlen(argv[SMB_PWD_NTHASH]);
    if (nt_len == SMBAUTH_HEXHASH_SZ) {
        (void) hextobin(argv[SMB_PWD_NTHASH], SMBAUTH_HEXHASH_SZ,
            (char *)pw->pw_nthash, SMBAUTH_HASH_SZ);

        pw->pw_flags |= SMB_PWF_NT;
    } else if (nt_len != 0) {
        return (NULL);
    }

    return (pwbuf);
}

/*
 * smb_pwd_chgpwent
 *
 * Updates the given smb_passwd_t structure with given password and
 * control information.
 */
static int
smb_pwd_chgpwent(smb_passwd_t *smbpw, const char *password, int control)
{
    if (control & SMB_PWC_DISABLE) {
        /* disable the user */
        smbpw->pw_flags |= SMB_PWF_DISABLE;
        (void) strcpy((char *)smbpw->pw_lmhash, SMB_PWD_DISABLE);
        (void) strcpy((char *)smbpw->pw_nthash, SMB_PWD_DISABLE);
        smbpw->pw_flags &= ~(SMB_PWF_LM | SMB_PWF_NT);
        return (SMB_PWE_SUCCESS);
    }

    if ((control & SMB_PWC_ENABLE) && (smbpw->pw_flags & SMB_PWF_DISABLE)) {
        /* enable the user if it's been disabled */
        *smbpw->pw_lmhash = '\0';
        *smbpw->pw_nthash = '\0';
        smbpw->pw_flags &= ~(SMB_PWF_LM | SMB_PWF_NT);
        return (SMB_PWE_SUCCESS);
    }

    /* No password update if account is disabled */
    if (smbpw->pw_flags & SMB_PWF_DISABLE)
        return (SMB_PWE_USER_DISABLE);

    /* This call was just to update the control flags */
    if (password == NULL)
        return (SMB_PWE_SUCCESS);

    if (control & SMB_PWC_NOLM) {
        /* LM hash should not be present */
        smbpw->pw_flags &= ~SMB_PWF_LM;
        *smbpw->pw_lmhash = '\0';
    } else {
        smbpw->pw_flags |= SMB_PWF_LM;
        (void) smb_auth_lm_hash(password, smbpw->pw_lmhash);
    }

    smbpw->pw_flags |= SMB_PWF_NT;
    (void) smb_auth_ntlm_hash(password, smbpw->pw_nthash);
    return (SMB_PWE_SUCCESS);
}

/*
 * smb_pwd_fputent
 *
 * If LM/NTLM hash are present, converts them to hex string
 * and write them along with user's name and Id to the smbpasswd
 * file.
 */
static int
smb_pwd_fputent(FILE *fp, const smb_pwbuf_t *pwbuf)
{
    smb_passwd_t *pw = pwbuf->pw_pwd;
    char hex_nthash[SMBAUTH_HEXHASH_SZ+1];
    char hex_lmhash[SMBAUTH_HEXHASH_SZ+1];
    int rc;

    if ((pw->pw_flags & SMB_PWF_LM) == SMB_PWF_LM) {
        (void) bintohex((char *)pw->pw_lmhash, SMBAUTH_HASH_SZ,
            hex_lmhash, SMBAUTH_HEXHASH_SZ);
        hex_lmhash[SMBAUTH_HEXHASH_SZ] = '\0';
    } else {
        (void) strcpy(hex_lmhash, (char *)pw->pw_lmhash);
    }

    if ((pw->pw_flags & SMB_PWF_NT) == SMB_PWF_NT) {
        (void) bintohex((char *)pw->pw_nthash, SMBAUTH_HASH_SZ,
            hex_nthash, SMBAUTH_HEXHASH_SZ);
        hex_nthash[SMBAUTH_HEXHASH_SZ] = '\0';
    } else {
        (void) strcpy(hex_nthash, (char *)pw->pw_nthash);
    }

    rc = fprintf(fp, "%s:%u:%s:%s\n", pw->pw_name, pw->pw_uid,
        hex_lmhash, hex_nthash);

    if (rc <= 0)
        return (SMB_PWE_WRITE_FAILED);

    return (SMB_PWE_SUCCESS);
}

/*
 * smb_pwd_lock
 *
 * A wrapper around smb_pwd_flck() which locks smb password
 * file so that only one thread at a time is operational.
 */
static int
smb_pwd_lock(void)
{
    int res;

    if (smb_pwd_flck()) {
        switch (errno) {
        case EINTR:
            res = SMB_PWE_BUSY;
            break;
        case EACCES:
            res = SMB_PWE_DENIED;
            break;
        case 0:
            res = SMB_PWE_SUCCESS;
            break;
        }
    } else
        res = SMB_PWE_SUCCESS;

    return (res);
}

/*
 * smb_pwd_unlock
 *
 * A wrapper around smb_pwd_fulck() which unlocks
 * smb password file.
 */
static int
smb_pwd_unlock(void)
{
    if (smb_pwd_fulck())
        return (SMB_PWE_SYSTEM_ERROR);

    return (SMB_PWE_SUCCESS);
}

/*
 * smb_pwd_flck
 *
 * Creates a lock file and grabs an exclusive (write) lock on it.
 */
static int
smb_pwd_flck(void)
{
    int seconds = 0;

    (void) mutex_lock(&lck_lock);
    for (;;) {
        if (lck_pid != 0 && lck_pid != getpid()) {
            /* somebody forked */
            lck_pid = 0;
            lck_tid = 0;
        }

        if (lck_tid == 0) {
            if ((fildes = creat(SMB_PASSLCK, 0600)) == -1)
                break;
            flock.l_type = F_WRLCK;
            if (fcntl(fildes, F_SETLK, &flock) != -1) {
                lck_pid = getpid();
                lck_tid = thr_self();
                (void) mutex_unlock(&lck_lock);
                return (0);
            }
            (void) close(fildes);
            fildes = -1;
        }

        if (seconds++ >= S_WAITTIME) {
            /*
             * For compatibility with the past, pretend
             * that we were interrupted by SIGALRM.
             */
            errno = EINTR;
            break;
        }

        (void) mutex_unlock(&lck_lock);
        (void) sleep(1);
        (void) mutex_lock(&lck_lock);
    }
    (void) mutex_unlock(&lck_lock);

    return (-1);
}

/*
 * smb_pwd_fulck
 *
 * Unlocks smb password file for operations done via
 * this library APIs.
 */
static int
smb_pwd_fulck(void)
{
    (void) mutex_lock(&lck_lock);
    if (lck_tid == thr_self() && fildes >= 0) {
        flock.l_type = F_UNLCK;
        (void) fcntl(fildes, F_SETLK, &flock);
        (void) close(fildes);
        fildes = -1;
        lck_pid = 0;
        lck_tid = 0;
        (void) mutex_unlock(&lck_lock);
        return (0);
    }
    (void) mutex_unlock(&lck_lock);
    return (-1);
}

/*
 * Local User Cache Functions
 *
 * Local user cache is implemented using AVL tree
 */

/*
 * smb_lucache_cmp
 *
 * AVL compare function, the key is username.
 */
static int
smb_lucache_cmp(const void *p1, const void *p2)
{
    smb_ucnode_t *u1 = (smb_ucnode_t *)p1;
    smb_ucnode_t *u2 = (smb_ucnode_t *)p2;
    int rc;

    rc = strcmp(u1->cn_user.su_name, u2->cn_user.su_name);

    if (rc < 0)
        return (-1);

    if (rc > 0)
        return (1);

    return (0);
}

/*
 * smb_lucache_update
 *
 * Updates the cache if needed. Whether an update is needed
 * is determined based on smbpasswd file modification timestamp
 */
static void
smb_lucache_update(void)
{
    struct stat64 stbuf;
    int rc;

    (void) mutex_lock(&smb_uch.uc_mtx);
    switch (smb_uch.uc_state) {
    default:
    case SMB_UCHS_NOCACHE:
        assert(0);
        (void) mutex_unlock(&smb_uch.uc_mtx);
        return;

    case SMB_UCHS_CREATED:
    case SMB_UCHS_UPDATED:
        break;

    case SMB_UCHS_UPDATING:
        /* Want only one thread executing this function at a time */
        (void) mutex_unlock(&smb_uch.uc_mtx);
        return;

    case SMB_UCHS_DESTROYING:
        (void) mutex_unlock(&smb_uch.uc_mtx);
        return;
    }

    /*
     * smb_pwd_lock() is not called here so it can
     * be checked quickly whether an updated is needed
     */
    if (stat64(SMB_PASSWD, &stbuf) < 0) {
        (void) mutex_unlock(&smb_uch.uc_mtx);
        if (errno != ENOENT)
            return;

        /* no smbpasswd file; empty the cache */
        smb_lucache_flush();
        return;
    }

    if (stbuf.st_size == 0) {
        (void) mutex_unlock(&smb_uch.uc_mtx);

        /* empty smbpasswd file; empty the cache */
        smb_lucache_flush();
        return;
    }

    if ((smb_uch.uc_timestamp.tv_sec == stbuf.st_mtim.tv_sec) &&
        (smb_uch.uc_timestamp.tv_nsec == stbuf.st_mtim.tv_nsec)) {
        (void) mutex_unlock(&smb_uch.uc_mtx);
        /* No changes since the last cache update */
        return;
    }

    smb_uch.uc_state = SMB_UCHS_UPDATING;
    smb_uch.uc_refcnt++;
    (void) mutex_unlock(&smb_uch.uc_mtx);

    rc = smb_lucache_do_update();

    (void) mutex_lock(&smb_uch.uc_mtx);
    if ((rc == SMB_PWE_SUCCESS) && (stat64(SMB_PASSWD, &stbuf) == 0))
        smb_uch.uc_timestamp = stbuf.st_mtim;
    smb_uch.uc_state = SMB_UCHS_UPDATED;
    smb_uch.uc_refcnt--;
    (void) cond_broadcast(&smb_uch.uc_cv);
    (void) mutex_unlock(&smb_uch.uc_mtx);
}

/*
 * smb_lucache_do_update
 *
 * This function takes care of updating the AVL tree.
 * If an entry has been updated, it'll be modified in place.
 *
 * New entries will be added to a temporary AVL tree then
 * passwod file is unlocked and all the new entries will
 * be transferred to the main cache from the temporary tree.
 *
 * This function MUST NOT be called directly
 */
static int
smb_lucache_do_update(void)
{
    avl_tree_t tmp_cache;
    smb_pwbuf_t pwbuf;
    smb_passwd_t smbpw;
    smb_ucnode_t uc_node;
    smb_ucnode_t *uc_newnode;
    smb_luser_t *user;
    smb_sid_t *sid;
    idmap_stat idm_stat;
    int rc = SMB_PWE_SUCCESS;
    void *cookie = NULL;
    FILE *fp;

    if ((rc = smb_pwd_lock()) != SMB_PWE_SUCCESS)
        return (rc);

    if ((fp = fopen(SMB_PASSWD, "rF")) == NULL) {
        (void) smb_pwd_unlock();
        return (SMB_PWE_OPEN_FAILED);
    }

    avl_create(&tmp_cache, smb_lucache_cmp,
        sizeof (smb_ucnode_t), offsetof(smb_ucnode_t, cn_link));

    bzero(&pwbuf, sizeof (smb_pwbuf_t));
    pwbuf.pw_pwd = &smbpw;

    (void) rw_rdlock(&smb_uch.uc_cache_lck);

    while (smb_pwd_fgetent(fp, &pwbuf, SMB_PWD_GETF_NOPWD) != NULL) {
        uc_node.cn_user.su_name = smbpw.pw_name;
        uc_newnode = avl_find(&smb_uch.uc_cache, &uc_node, NULL);
        if (uc_newnode) {
            /* update the node info */
            uc_newnode->cn_user.su_ctrl = smbpw.pw_flags;
            continue;
        }

        /* create a new node */
        if ((uc_newnode = malloc(sizeof (smb_ucnode_t))) == NULL) {
            rc = SMB_PWE_NO_MEMORY;
            break;
        }

        bzero(uc_newnode, sizeof (smb_ucnode_t));
        user = &uc_newnode->cn_user;
        user->su_ctrl = smbpw.pw_flags;

        idm_stat = smb_idmap_getsid(smbpw.pw_uid, SMB_IDMAP_USER, &sid);
        if (idm_stat != IDMAP_SUCCESS) {
            syslog(LOG_WARNING, "smb_pwdutil: couldn't obtain SID "
                "for uid=%u (%d)", smbpw.pw_uid, idm_stat);
            free(uc_newnode);
            continue;
        }
        (void) smb_sid_getrid(sid, &user->su_rid);
        smb_sid_free(sid);

        user->su_name = strdup(smbpw.pw_name);
        if (user->su_name == NULL) {
            rc = SMB_PWE_NO_MEMORY;
            free(uc_newnode);
            break;
        }

        avl_add(&tmp_cache, uc_newnode);
    }

    (void) rw_unlock(&smb_uch.uc_cache_lck);
    (void) fclose(fp);
    (void) smb_pwd_unlock();

    /* Destroy the temporary list */
    (void) rw_wrlock(&smb_uch.uc_cache_lck);
    while ((uc_newnode = avl_destroy_nodes(&tmp_cache, &cookie)) != NULL) {
        avl_add(&smb_uch.uc_cache, uc_newnode);
    }
    (void) rw_unlock(&smb_uch.uc_cache_lck);

    avl_destroy(&tmp_cache);

    return (rc);
}

/*
 * smb_lucache_create
 *
 * Creates the AVL tree and initializes the global user cache handle.
 * This function doesn't populate the cache.
 * User cache is only created by smbd at startup
 */
static void
smb_lucache_create(void)
{
    (void) mutex_lock(&smb_uch.uc_mtx);
    if (smb_uch.uc_state != SMB_UCHS_NOCACHE) {
        (void) mutex_unlock(&smb_uch.uc_mtx);
        return;
    }

    avl_create(&smb_uch.uc_cache, smb_lucache_cmp,
        sizeof (smb_ucnode_t), offsetof(smb_ucnode_t, cn_link));

    smb_uch.uc_state = SMB_UCHS_CREATED;
    bzero(&smb_uch.uc_timestamp, sizeof (timestruc_t));
    smb_uch.uc_refcnt = 0;
    (void) mutex_unlock(&smb_uch.uc_mtx);
}

/*
 * smb_lucache_flush
 *
 * Removes and frees all the cache entries
 */
static void
smb_lucache_flush(void)
{
    void *cookie = NULL;
    smb_ucnode_t *ucnode;

    (void) rw_wrlock(&smb_uch.uc_cache_lck);
    while ((ucnode = avl_destroy_nodes(&smb_uch.uc_cache, &cookie))
        != NULL) {
        free(ucnode->cn_user.su_name);
        free(ucnode->cn_user.su_fullname);
        free(ucnode->cn_user.su_desc);
        free(ucnode);
    }
    (void) rw_unlock(&smb_uch.uc_cache_lck);
}

/*
 * smb_lucache_destroy
 *
 * Destroys the cache.
 * This function is only called in smb_pwd_fini()
 * User cache is only destroyed by smbd upon shutdown
 */
static void
smb_lucache_destroy(void)
{
    (void) mutex_lock(&smb_uch.uc_mtx);
    switch (smb_uch.uc_state) {
    case SMB_UCHS_NOCACHE:
    case SMB_UCHS_DESTROYING:
        (void) mutex_unlock(&smb_uch.uc_mtx);
        return;

    default:
        break;
    }

    smb_uch.uc_state = SMB_UCHS_DESTROYING;

    while (smb_uch.uc_refcnt > 0)
        (void) cond_wait(&smb_uch.uc_cv, &smb_uch.uc_mtx);

    smb_lucache_flush();

    avl_destroy(&smb_uch.uc_cache);
    smb_uch.uc_state = SMB_UCHS_NOCACHE;
    (void) mutex_unlock(&smb_uch.uc_mtx);
}

/*
 * smb_lucache_lock
 *
 * Locks the user cache for reading and also
 * increment the handle reference count.
 */
static int
smb_lucache_lock(void)
{
    (void) mutex_lock(&smb_uch.uc_mtx);
    switch (smb_uch.uc_state) {
    case SMB_UCHS_NOCACHE:
        assert(0);
        (void) mutex_unlock(&smb_uch.uc_mtx);
        return (SMB_PWE_DENIED);

    case SMB_UCHS_DESTROYING:
        (void) mutex_unlock(&smb_uch.uc_mtx);
        return (SMB_PWE_DENIED);
    }
    smb_uch.uc_refcnt++;
    (void) mutex_unlock(&smb_uch.uc_mtx);

    (void) rw_rdlock(&smb_uch.uc_cache_lck);
    return (SMB_PWE_SUCCESS);
}

/*
 * smb_lucache_unlock
 *
 * Unlock the cache
 */
static void
smb_lucache_unlock(void)
{
    (void) rw_unlock(&smb_uch.uc_cache_lck);

    (void) mutex_lock(&smb_uch.uc_mtx);
    smb_uch.uc_refcnt--;
    (void) cond_broadcast(&smb_uch.uc_cv);
    (void) mutex_unlock(&smb_uch.uc_mtx);
}

/*
 * smb_lucache_num
 *
 * Returns the number of cache entries
 */
static int
smb_lucache_num(void)
{
    int num;

    (void) mutex_lock(&smb_uch.uc_mtx);
    switch (smb_uch.uc_state) {
    case SMB_UCHS_NOCACHE:
        assert(0);
        (void) mutex_unlock(&smb_uch.uc_mtx);
        return (0);

    case SMB_UCHS_DESTROYING:
        (void) mutex_unlock(&smb_uch.uc_mtx);
        return (0);
    }
    (void) mutex_unlock(&smb_uch.uc_mtx);

    (void) rw_rdlock(&smb_uch.uc_cache_lck);
    num = (int)avl_numnodes(&smb_uch.uc_cache);
    (void) rw_unlock(&smb_uch.uc_cache_lck);

    return (num);
}