/*      $NetBSD: passwd.c,v 1.53 2018/06/24 01:53:14 kamil Exp $        */

/*
 * Copyright (c) 1987, 1993, 1994, 1995
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 * 3. Neither the name of the University 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 REGENTS 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 REGENTS 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 <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: passwd.c,v 1.53 2018/06/24 01:53:14 kamil Exp $");
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>

#include <assert.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <paths.h>
#include <pwd.h>
#include <grp.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <util.h>

static const char      *pw_filename(const char *filename);
static void             pw_cont(int sig);
static const char *     pw_equal(char *buf, struct passwd *old_pw);
static const char      *pw_default(const char *option);
static int              read_line(FILE *fp, char *line, int max);
static void             trim_whitespace(char *line);

static  char    pw_prefix[MAXPATHLEN];

const char *
pw_getprefix(void)
{

        return(pw_prefix);
}

int
pw_setprefix(const char *new_prefix)
{
        size_t length;

        _DIAGASSERT(new_prefix != NULL);

        length = strlen(new_prefix);
        if (length < sizeof(pw_prefix)) {
                (void)strcpy(pw_prefix, new_prefix);
                while (length > 0 && pw_prefix[length - 1] == '/')
                        pw_prefix[--length] = '\0';
                return(0);
        }
        errno = ENAMETOOLONG;
        return(-1);
}

static const char *
pw_filename(const char *filename)
{
        static char newfilename[MAXPATHLEN];

        _DIAGASSERT(filename != NULL);

        if (pw_prefix[0] == '\0')
                return filename;

        if (strlen(pw_prefix) + strlen(filename) < sizeof(newfilename))
                return strcat(strcpy(newfilename, pw_prefix), filename);

        errno = ENAMETOOLONG;
        return(NULL);
}

int
pw_lock(int retries)
{
        const char *filename;
        int i, fd;
        mode_t old_mode;
        int oerrno;

        /* Acquire the lock file. */
        filename = pw_filename(_PATH_MASTERPASSWD_LOCK);
        if (filename == NULL)
                return(-1);
        old_mode = umask(0);
        fd = open(filename, O_WRONLY|O_CREAT|O_EXCL, 0600);
        for (i = 0; i < retries && fd < 0 && errno == EEXIST; i++) {
                sleep(1);
                fd = open(filename, O_WRONLY|O_CREAT|O_EXCL,
                          0600);
        }
        oerrno = errno;
        (void)umask(old_mode);
        errno = oerrno;
        return(fd);
}

int
pw_mkdb(const char *username, int secureonly)
{
        const char *args[9];
        int pstat, i;
        pid_t pid;

        pid = vfork();
        if (pid == -1)
                return -1;

        if (pid == 0) {
                args[0] = "pwd_mkdb";
                args[1] = "-d";
                args[2] = pw_prefix;
                args[3] = "-pl";
                i = 4;

                if (secureonly)
                        args[i++] = "-s";
                if (username != NULL) {
                        args[i++] = "-u";
                        args[i++] = username;
                }

                args[i++] = pw_filename(_PATH_MASTERPASSWD_LOCK);
                args[i] = NULL;
                execv(_PATH_PWD_MKDB, (char * const *)__UNCONST(args));
                _exit(1);
        }
        pid = waitpid(pid, &pstat, 0);
        if (pid == -1) {
                warn("error waiting for pid %lu", (unsigned long)pid);
                return -1;
        }
        if (WIFEXITED(pstat)) {
                if (WEXITSTATUS(pstat) != 0) {
                        warnx("pwd_mkdb exited with status %d",
                            WEXITSTATUS(pstat));
                        return -1;
                }
        } else if (WIFSIGNALED(pstat)) {
                warnx("pwd_mkdb exited with signal %d", WTERMSIG(pstat));
                return -1;
        }
        return 0;
}

int
pw_abort(void)
{
        const char *filename;

        filename = pw_filename(_PATH_MASTERPASSWD_LOCK);
        return((filename == NULL) ? -1 : unlink(filename));
}

/* Everything below this point is intended for the convenience of programs
 * which allow a user to interactively edit the passwd file.  Errors in the
 * routines below will cause the process to abort. */

static pid_t editpid = -1;

static void
pw_cont(int sig)
{

        if (editpid != -1)
                kill(editpid, sig);
}

void
pw_init(void)
{
        struct rlimit rlim;

        /* Unlimited resource limits. */
        rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
        (void)setrlimit(RLIMIT_CPU, &rlim);
        (void)setrlimit(RLIMIT_FSIZE, &rlim);
        (void)setrlimit(RLIMIT_STACK, &rlim);
        (void)setrlimit(RLIMIT_DATA, &rlim);
        (void)setrlimit(RLIMIT_RSS, &rlim);

        /* Don't drop core (not really necessary, but GP's). */
        rlim.rlim_cur = rlim.rlim_max = 0;
        (void)setrlimit(RLIMIT_CORE, &rlim);

        /* Turn off signals. */
        (void)signal(SIGALRM, SIG_IGN);
        (void)signal(SIGHUP, SIG_IGN);
        (void)signal(SIGINT, SIG_IGN);
        (void)signal(SIGPIPE, SIG_IGN);
        (void)signal(SIGQUIT, SIG_IGN);
        (void)signal(SIGTERM, SIG_IGN);
        (void)signal(SIGCONT, pw_cont);
}

void
pw_edit(int notsetuid, const char *filename)
{
        int pstat;
        char *p;
        const char * volatile editor;
        const char *argp[] = { "sh", "-c", NULL, NULL };

        if (filename == NULL)
                filename = _PATH_MASTERPASSWD_LOCK;

        filename = pw_filename(filename);
        if (filename == NULL)
                return;

        if ((editor = getenv("EDITOR")) == NULL)
                editor = _PATH_VI;

        p = malloc(strlen(editor) + 1 + strlen(filename) + 1);
        if (p == NULL)
                return;

        sprintf(p, "%s %s", editor, filename);
        argp[2] = p;

        switch(editpid = vfork()) {
        case -1:
                free(p);
                return;
        case 0:
                if (notsetuid) {
                        setgid(getgid());
                        setuid(getuid());
                }
                execvp(_PATH_BSHELL, (char *const *)__UNCONST(argp));
                _exit(1);
        }

        free(p);

        for (;;) {
                editpid = waitpid(editpid, (int *)&pstat, WUNTRACED);
                if (editpid == -1)
                        pw_error(editor, 1, 1);
                else if (WIFSTOPPED(pstat))
                        raise(WSTOPSIG(pstat));
                else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
                        break;
                else
                        pw_error(editor, 1, 1);
        }
        editpid = -1;
}

void
pw_prompt(void)
{
        int c;

        (void)printf("re-edit the password file? [y]: ");
        (void)fflush(stdout);
        c = getchar();
        if (c != EOF && c != '\n')
                while (getchar() != '\n');
        if (c == 'n')
                pw_error(NULL, 0, 0);
}

/* for use in pw_copy(). Compare a pw entry to a pw struct. */
/* returns a character string labelling the miscompared field or 0 */
static const char *
pw_equal(char *buf, struct passwd *pw)
{
        struct passwd buf_pw;
        size_t len;

        _DIAGASSERT(buf != NULL);
        _DIAGASSERT(pw != NULL);

        len = strlen (buf);
        if (buf[len-1] == '\n')
                buf[len-1] = '\0';
        if (!pw_scan(buf, &buf_pw, NULL))
                return "corrupt line";
        if (strcmp(pw->pw_name, buf_pw.pw_name) != 0)
                return "name";
        if (pw->pw_uid != buf_pw.pw_uid)
                return "uid";
        if (pw->pw_gid != buf_pw.pw_gid)
                return "gid";
        if (strcmp( pw->pw_class, buf_pw.pw_class) != 0)
                return "class";
        if (pw->pw_change != buf_pw.pw_change)
                return "change";
        if (pw->pw_expire != buf_pw.pw_expire)
                return "expire";
        if (strcmp( pw->pw_gecos, buf_pw.pw_gecos) != 0)
                return "gecos";
        if (strcmp( pw->pw_dir, buf_pw.pw_dir) != 0)
                return "dir";
        if (strcmp( pw->pw_shell, buf_pw.pw_shell) != 0)
                return "shell";
        return (char *)0;
}

void
pw_copy(int ffd, int tfd, struct passwd *pw, struct passwd *old_pw)
{
        char errbuf[200];
        int rv;

        rv = pw_copyx(ffd, tfd, pw, old_pw, errbuf, sizeof(errbuf));
        if (rv == 0) {
                warnx("%s", errbuf);
                pw_error(NULL, 0, 1);
        }
}

static void
pw_print(FILE *to, const struct passwd *pw)
{
        (void)fprintf(to, "%s:%s:%d:%d:%s:%lld:%lld:%s:%s:%s\n",
            pw->pw_name, pw->pw_passwd, pw->pw_uid, pw->pw_gid,
            pw->pw_class, (long long)pw->pw_change,
            (long long)pw->pw_expire,
            pw->pw_gecos, pw->pw_dir, pw->pw_shell);
}

int
pw_copyx(int ffd, int tfd, struct passwd *pw, struct passwd *old_pw,
    char *errbuf, size_t errbufsz)
{
        const char *filename;
        char mpwd[MAXPATHLEN], mpwdl[MAXPATHLEN], *p, buf[8192];
        FILE *from, *to;
        int done;

        _DIAGASSERT(pw != NULL);
        _DIAGASSERT(errbuf != NULL);
        /* old_pw may be NULL */

        if ((filename = pw_filename(_PATH_MASTERPASSWD)) == NULL) {
                snprintf(errbuf, errbufsz, "%s: %s", pw_prefix,
                    strerror(errno));
                return (0);
        }
        (void)strcpy(mpwd, filename);
        if ((filename = pw_filename(_PATH_MASTERPASSWD_LOCK)) == NULL) {
                snprintf(errbuf, errbufsz, "%s: %s", pw_prefix,
                    strerror(errno));
                return (0);
        }
        (void)strcpy(mpwdl, filename);

        if (!(from = fdopen(ffd, "r"))) {
                snprintf(errbuf, errbufsz, "%s: %s", mpwd, strerror(errno));
                return (0);
        }
        if (!(to = fdopen(tfd, "w"))) {
                snprintf(errbuf, errbufsz, "%s: %s", mpwdl, strerror(errno));
                (void)fclose(from);
                return (0);
        }

        for (done = 0; fgets(buf, (int)sizeof(buf), from);) {
                const char *neq;
                if (!strchr(buf, '\n')) {
                        snprintf(errbuf, errbufsz, "%s: line too long", mpwd);
                        (void)fclose(from);
                        (void)fclose(to);
                        return (0);
                }
                if (done) {
                        (void)fprintf(to, "%s", buf);
                        if (ferror(to)) {
                                snprintf(errbuf, errbufsz, "%s",
                                    strerror(errno));
                                (void)fclose(from);
                                (void)fclose(to);
                                return (0);
                        }
                        continue;
                }
                if (!(p = strchr(buf, ':'))) {
                        snprintf(errbuf, errbufsz, "%s: corrupted entry", mpwd);
                        (void)fclose(from);
                        (void)fclose(to);
                        return (0);
                }
                *p = '\0';
                if (strcmp(buf, pw->pw_name)) {
                        *p = ':';
                        (void)fprintf(to, "%s", buf);
                        if (ferror(to)) {
                                snprintf(errbuf, errbufsz, "%s",
                                    strerror(errno));
                                (void)fclose(from);
                                (void)fclose(to);
                                return (0);
                        }
                        continue;
                }
                *p = ':';
                if (old_pw && (neq = pw_equal(buf, old_pw)) != NULL) {
                        if (strcmp(neq, "corrupt line") == 0)
                                (void)snprintf(errbuf, errbufsz,
                                    "%s: entry %s corrupted", mpwd,
                                    pw->pw_name);
                        else
                                (void)snprintf(errbuf, errbufsz,
                                    "%s: entry %s inconsistent %s",
                                    mpwd, pw->pw_name, neq);
                        (void)fclose(from);
                        (void)fclose(to);
                        return (0);
                }
                pw_print(to, pw);
                done = 1;
                if (ferror(to)) {
                        snprintf(errbuf, errbufsz, "%s", strerror(errno));
                        (void)fclose(from);
                        (void)fclose(to);
                        return (0);
                }
        }
        /* Only append a new entry if real uid is root! */
        if (!done) {
                if (getuid() == 0) {
                        pw_print(to, pw);
                        done = 1;
                } else {
                        snprintf(errbuf, errbufsz,
                            "%s: changes not made, no such entry", mpwd);
                }
        }

        if (ferror(to)) {
                snprintf(errbuf, errbufsz, "%s", strerror(errno));
                (void)fclose(from);
                (void)fclose(to);
                return (0);
        }
        (void)fclose(from);
        (void)fclose(to);

        return (done);
}

void
pw_error(const char *name, int error, int eval)
{

        if (error) {
                if (name)
                        warn("%s", name);
                else
                        warn(NULL);
        }

        warnx("%s%s: unchanged", pw_prefix, _PATH_MASTERPASSWD);
        pw_abort();
        exit(eval);
}

/* Removes head and/or tail spaces. */
static void
trim_whitespace(char *line)
{
        char *p;

        _DIAGASSERT(line != NULL);

        /* Handle empty string */
        if (*line == '\0')
                return;

        /* Remove leading spaces */
        p = line;
        while (isspace((unsigned char) *p))
                p++;
        memmove(line, p, strlen(p) + 1);

        /* Handle empty string after removal of whitespace characters */
        if (*line == '\0')
                return;

        /* Remove trailing spaces, line must not be empty string here */
        p = line + strlen(line) - 1;
        while (isspace((unsigned char) *p))
                p--;
        *(p + 1) = '\0';
}


/* Get one line, remove spaces from front and tail */
static int
read_line(FILE *fp, char *line, int max)
{
        char   *p;

        _DIAGASSERT(fp != NULL);
        _DIAGASSERT(line != NULL);

        /* Read one line of config */
        if (fgets(line, max, fp) == NULL)
                return (0);

        if ((p = strchr(line, '\n')) == NULL) {
                warnx("line too long");
                return (0);
        }
        *p = '\0';

        /* Remove comments */
        if ((p = strchr(line, '#')) != NULL)
                *p = '\0';

        trim_whitespace(line);
        return (1);
}

static const char *
pw_default(const char *option)
{
        static const char *options[][2] = {
                { "localcipher",        "old" },
                { "ypcipher",           "old" },
        };
        size_t i;

        _DIAGASSERT(option != NULL);
        for (i = 0; i < sizeof(options) / sizeof(options[0]); i++)
                if (strcmp(options[i][0], option) == 0)
                        return (options[i][1]);

        return (NULL);
}

/*
 * Retrieve password information from the /etc/passwd.conf file, at the
 * moment this is only for choosing the cipher to use.  It could easily be
 * used for other authentication methods as well.
 */
void
pw_getconf(char *data, size_t max, const char *key, const char *option)
{
        FILE *fp;
        char line[LINE_MAX], *p, *p2;
        static char result[LINE_MAX];
        int got, found;
        const char *cp;

        _DIAGASSERT(data != NULL);
        _DIAGASSERT(key != NULL);
        _DIAGASSERT(option != NULL);

        got = 0;
        found = 0;
        result[0] = '\0';

        if ((fp = fopen(_PATH_PASSWD_CONF, "r")) == NULL) {
                if ((cp = pw_default(option)) != NULL)
                        strlcpy(data, cp, max);
                else
                        data[0] = '\0';
                return;
        }

        while (!found && (got || read_line(fp, line, LINE_MAX))) {
                got = 0;

                if (strncmp(key, line, strlen(key)) != 0 ||
                    line[strlen(key)] != ':')
                        continue;

                /* Now we found our specified key */
                while (read_line(fp, line, LINE_MAX)) {
                        /* Leaving key field */
                        if (line[0] != '\0' && strchr(line + 1, ':') != NULL) {
                                got = 1;
                                break;
                        }
                        p2 = line;
                        if ((p = strsep(&p2, "=")) == NULL || p2 == NULL)
                                continue;
                        trim_whitespace(p);

                        if (!strncmp(p, option, strlen(option))) {
                                trim_whitespace(p2);
                                strcpy(result, p2);
                                found = 1;
                                break;
                        }
                }
        }
        fclose(fp);

        if (!found)
                errno = ENOENT;
        if (!got)
                errno = ENOTDIR;

        /* 
         * If we got no result and were looking for a default
         * value, try hard coded defaults.
         */

        if (strlen(result) == 0 && strcmp(key, "default") == 0 &&
            (cp = pw_default(option)) != NULL)
                strlcpy(data, cp, max);
        else 
                strlcpy(data, result, max);
}

void
pw_getpwconf(char *data, size_t max, const struct passwd *pwd,
    const char *option)
{
        char grpkey[LINE_MAX];
        struct group grs, *grp;
        char grbuf[1024];

        pw_getconf(data, max, pwd->pw_name, option);

        /* Try to find an entry for the group */
        if (*data == '\0') {
                (void)getgrgid_r(pwd->pw_gid, &grs, grbuf, sizeof(grbuf), &grp);
                if (grp != NULL) {
                        (void)snprintf(grpkey, sizeof(grpkey), ":%s",
                            grp->gr_name);
                        pw_getconf(data, max, grpkey, option);
                }
                if (*data == '\0')
                        pw_getconf(data, max, "default", option);
        }
}