/*
 *
 * Copyright (c) 2001 Gert Doering.  All rights reserved.
 * Copyright (c) 2003,2004,2005,2006 Darren Tucker.  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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 "includes.h"

#ifdef _AIX

#include "xmalloc.h"
#include "sshbuf.h"
#include "ssherr.h"
#include "sshkey.h"
#include "hostfile.h"
#include "auth.h"
#include "ssh.h"
#include "ssh_api.h"
#include "log.h"

#include <errno.h>
#if defined(HAVE_NETDB_H)
# include <netdb.h>
#endif
#include <uinfo.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>

#ifdef WITH_AIXAUTHENTICATE
# include <login.h>
# include <userpw.h>
# if defined(HAVE_SYS_AUDIT_H) && defined(AIX_LOGINFAILED_4ARG)
#  include <sys/audit.h>
# endif
# include <usersec.h>
#endif

#include "port-aix.h"

static char *lastlogin_msg = NULL;

# ifdef HAVE_SETAUTHDB
static char old_registry[REGISTRY_SIZE] = "";
# endif

/*
 * AIX has a "usrinfo" area where logname and other stuff is stored -
 * a few applications actually use this and die if it's not set
 *
 * NOTE: TTY= should be set, but since no one uses it and it's hard to
 * acquire due to privsep code.  We will just drop support.
 */
void
aix_usrinfo(struct passwd *pw)
{
        u_int i;
        size_t len;
        char *cp;

        len = sizeof("LOGNAME= NAME= ") + (2 * strlen(pw->pw_name));
        cp = xmalloc(len);

        i = snprintf(cp, len, "LOGNAME=%s%cNAME=%s%c", pw->pw_name, '\0',
            pw->pw_name, '\0');
        if (usrinfo(SETUINFO, cp, i) == -1)
                fatal("Couldn't set usrinfo: %s", strerror(errno));
        debug3("AIX/UsrInfo: set len %d", i);

        free(cp);
}

# ifdef WITH_AIXAUTHENTICATE
/*
 * Remove embedded newlines in string (if any).
 * Used before logging messages returned by AIX authentication functions
 * so the message is logged on one line.
 */
void
aix_remove_embedded_newlines(char *p)
{
        if (p == NULL)
                return;

        for (; *p; p++) {
                if (*p == '\n')
                        *p = ' ';
        }
        /* Remove trailing whitespace */
        if (*--p == ' ')
                *p = '\0';
}

/*
 * Test specifically for the case where SYSTEM == NONE and AUTH1 contains
 * anything other than NONE or SYSTEM, which indicates that the admin has
 * configured the account for purely AUTH1-type authentication.
 *
 * Since authenticate() doesn't check AUTH1, and sshd can't sanely support
 * AUTH1 itself, in such a case authenticate() will allow access without
 * authentation, which is almost certainly not what the admin intends.
 *
 * (The native tools, eg login, will process the AUTH1 list in addition to
 * the SYSTEM list by using ckuserID(), however ckuserID() and AUTH1 methods
 * have been deprecated since AIX 4.2.x and would be very difficult for sshd
 * to support.
 *
 * Returns 0 if an unsupportable combination is found, 1 otherwise.
 */
static int
aix_valid_authentications(const char *user)
{
        char *auth1, *sys, *p;
        int valid = 1;

        if (getuserattr((char *)user, S_AUTHSYSTEM, &sys, SEC_CHAR) != 0) {
                logit("Can't retrieve attribute SYSTEM for %s: %.100s",
                    user, strerror(errno));
                return 0;
        }

        debug3("AIX SYSTEM attribute %s", sys);
        if (strcmp(sys, "NONE") != 0)
                return 1;       /* not "NONE", so is OK */

        if (getuserattr((char *)user, S_AUTH1, &auth1, SEC_LIST) != 0) {
                logit("Can't retrieve attribute auth1 for %s: %.100s",
                    user, strerror(errno));
                return 0;
        }

        p = auth1;
        /* A SEC_LIST is concatenated strings, ending with two NULs. */
        while (p[0] != '\0' && p[1] != '\0') {
                debug3("AIX auth1 attribute list member %s", p);
                if (strcmp(p, "NONE") != 0 && strcmp(p, "SYSTEM")) {
                        logit("Account %s has unsupported auth1 value '%s'",
                            user, p);
                        valid = 0;
                }
                p += strlen(p) + 1;
        }

        return (valid);
}

/*
 * Do authentication via AIX's authenticate routine.  We loop until the
 * reenter parameter is 0, but normally authenticate is called only once.
 *
 * Note: this function returns 1 on success, whereas AIX's authenticate()
 * returns 0.
 */
int
sys_auth_passwd(struct ssh *ssh, const char *password)
{
        Authctxt *ctxt = ssh->authctxt;
        char *authmsg = NULL, *msg = NULL, *name = ctxt->pw->pw_name;
        int r, authsuccess = 0, expired, reenter, result;

        do {
                result = authenticate((char *)name, (char *)password, &reenter,
                    &authmsg);
                aix_remove_embedded_newlines(authmsg);
                debug3("AIX/authenticate result %d, authmsg %.100s", result,
                    authmsg);
        } while (reenter);

        if (!aix_valid_authentications(name))
                result = -1;

        if (result == 0) {
                authsuccess = 1;

                /*
                 * Record successful login.  We don't have a pty yet, so just
                 * label the line as "ssh"
                 */
                aix_setauthdb(name);

                /*
                 * Check if the user's password is expired.
                 */
                expired = passwdexpired(name, &msg);
                if (msg && *msg) {
                        if ((r = sshbuf_put(ctxt->loginmsg,
                            msg, strlen(msg))) != 0)
                                fatal("%s: buffer error: %s",
                                    __func__, ssh_err(r));
                        aix_remove_embedded_newlines(msg);
                }
                debug3("AIX/passwdexpired returned %d msg %.100s", expired, msg);

                switch (expired) {
                case 0: /* password not expired */
                        break;
                case 1: /* expired, password change required */
                        ctxt->force_pwchange = 1;
                        break;
                default: /* user can't change(2) or other error (-1) */
                        logit("Password can't be changed for user %s: %.100s",
                            name, msg);
                        free(msg);
                        authsuccess = 0;
                }

                aix_restoreauthdb();
        }

        free(authmsg);

        return authsuccess;
}

/*
 * Check if specified account is permitted to log in.
 * Returns 1 if login is allowed, 0 if not allowed.
 */
int
sys_auth_allowed_user(struct passwd *pw, struct sshbuf *loginmsg)
{
        char *msg = NULL;
        int r, result, permitted = 0;
        struct stat st;

        /*
         * Don't perform checks for root account (PermitRootLogin controls
         * logins via ssh) or if running as non-root user (since
         * loginrestrictions will always fail due to insufficient privilege).
         */
        if (pw->pw_uid == 0 || geteuid() != 0) {
                debug3("%s: not checking", __func__);
                return 1;
        }

        result = loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &msg);
        if (result == 0)
                permitted = 1;
        /*
         * If restricted because /etc/nologin exists, the login will be denied
         * in session.c after the nologin message is sent, so allow for now
         * and do not append the returned message.
         */
        if (result == -1 && errno == EPERM && stat(_PATH_NOLOGIN, &st) == 0)
                permitted = 1;
        else if (msg != NULL) {
                if ((r = sshbuf_put(loginmsg, msg, strlen(msg))) != 0)
                        fatal("%s: buffer error: %s", __func__, ssh_err(r));
        }
        if (msg == NULL)
                msg = xstrdup("(none)");
        aix_remove_embedded_newlines(msg);
        debug3("AIX/loginrestrictions returned %d msg %.100s", result, msg);

        if (!permitted)
                logit("Login restricted for %s: %.100s", pw->pw_name, msg);
        free(msg);
        return permitted;
}

int
sys_auth_record_login(const char *user, const char *host, const char *ttynm,
    struct sshbuf *loginmsg)
{
        char *msg = NULL;
        int success = 0;

        aix_setauthdb(user);
        if (loginsuccess((char *)user, (char *)host, (char *)ttynm, &msg) == 0) {
                success = 1;
                if (msg != NULL) {
                        debug("AIX/loginsuccess: msg %s", msg);
                        if (lastlogin_msg == NULL)
                                lastlogin_msg = msg;
                }
        }
        aix_restoreauthdb();
        return (success);
}

char *
sys_auth_get_lastlogin_msg(const char *user, uid_t uid)
{
        char *msg = lastlogin_msg;

        lastlogin_msg = NULL;
        return msg;
}

#  ifdef CUSTOM_FAILED_LOGIN
/*
 * record_failed_login: generic "login failed" interface function
 */
void
record_failed_login(struct ssh *ssh, const char *user, const char *hostname,
    const char *ttyname)
{
        if (geteuid() != 0)
                return;

        aix_setauthdb(user);
#   ifdef AIX_LOGINFAILED_4ARG
        loginfailed((char *)user, (char *)hostname, (char *)ttyname,
            AUDIT_FAIL_AUTH);
#   else
        loginfailed((char *)user, (char *)hostname, (char *)ttyname);
#   endif
        aix_restoreauthdb();
}
#  endif /* CUSTOM_FAILED_LOGIN */

/*
 * If we have setauthdb, retrieve the password registry for the user's
 * account then feed it to setauthdb.  This will mean that subsequent AIX auth
 * functions will only use the specified loadable module.  If we don't have
 * setauthdb this is a no-op.
 */
void
aix_setauthdb(const char *user)
{
#  ifdef HAVE_SETAUTHDB
        char *registry;

        if (setuserdb(S_READ) == -1) {
                debug3("%s: Could not open userdb to read", __func__);
                return;
        }

        if (getuserattr((char *)user, S_REGISTRY, &registry, SEC_CHAR) == 0) {
                if (setauthdb(registry, old_registry) == 0)
                        debug3("AIX/setauthdb set registry '%s'", registry);
                else
                        debug3("AIX/setauthdb set registry '%s' failed: %s",
                            registry, strerror(errno));
        } else
                debug3("%s: Could not read S_REGISTRY for user: %s", __func__,
                    strerror(errno));
        enduserdb();
#  endif /* HAVE_SETAUTHDB */
}

/*
 * Restore the user's registry settings from old_registry.
 * Note that if the first aix_setauthdb fails, setauthdb("") is still safe
 * (it restores the system default behaviour).  If we don't have setauthdb,
 * this is a no-op.
 */
void
aix_restoreauthdb(void)
{
#  ifdef HAVE_SETAUTHDB
        if (setauthdb(old_registry, NULL) == 0)
                debug3("%s: restoring old registry '%s'", __func__,
                    old_registry);
        else
                debug3("%s: failed to restore old registry %s", __func__,
                    old_registry);
#  endif /* HAVE_SETAUTHDB */
}

# endif /* WITH_AIXAUTHENTICATE */

# ifdef USE_AIX_KRB_NAME
/*
 * aix_krb5_get_principal_name: returns the user's kerberos client principal
 * name if configured, otherwise NULL.  Caller must free returned string.
 */
char *
aix_krb5_get_principal_name(const char *const_pw_name)
{
        char *pw_name = (char *)const_pw_name;
        char *authname = NULL, *authdomain = NULL, *principal = NULL;

        setuserdb(S_READ);
        if (getuserattr(pw_name, S_AUTHDOMAIN, &authdomain, SEC_CHAR) != 0)
                debug("AIX getuserattr S_AUTHDOMAIN: %s", strerror(errno));
        if (getuserattr(pw_name, S_AUTHNAME, &authname, SEC_CHAR) != 0)
                debug("AIX getuserattr S_AUTHNAME: %s", strerror(errno));

        if (authdomain != NULL)
                xasprintf(&principal, "%s@%s", authname ? authname : pw_name,
                    authdomain);
        else if (authname != NULL)
                principal = xstrdup(authname);
        enduserdb();
        return principal;
}
# endif /* USE_AIX_KRB_NAME */

# if defined(AIX_GETNAMEINFO_HACK) && !defined(BROKEN_ADDRINFO)
# undef getnameinfo
/*
 * For some reason, AIX's getnameinfo will refuse to resolve the all-zeros
 * IPv6 address into its textual representation ("::"), so we wrap it
 * with a function that will.
 */
int
sshaix_getnameinfo(const struct sockaddr *sa, size_t salen, char *host,
    size_t hostlen, char *serv, size_t servlen, int flags)
{
        struct sockaddr_in6 *sa6;
        u_int32_t *a6;

        if (flags & (NI_NUMERICHOST|NI_NUMERICSERV) &&
            sa->sa_family == AF_INET6) {
                sa6 = (struct sockaddr_in6 *)sa;
                a6 = sa6->sin6_addr.u6_addr.u6_addr32;

                if (a6[0] == 0 && a6[1] == 0 && a6[2] == 0 && a6[3] == 0) {
                        strlcpy(host, "::", hostlen);
                        snprintf(serv, servlen, "%d", sa6->sin6_port);
                        return 0;
                }
        }
        return getnameinfo(sa, salen, host, hostlen, serv, servlen, flags);
}
# endif /* AIX_GETNAMEINFO_HACK */

# if defined(USE_GETGRSET)
#  include <stdlib.h>
int
getgrouplist(const char *user, gid_t pgid, gid_t *groups, int *grpcnt)
{
        char *cp, *grplist, *grp;
        gid_t gid;
        int ret = 0, ngroups = 0, maxgroups;
        long long ll;

        maxgroups = *grpcnt;

        if ((cp = grplist = getgrset(user)) == NULL)
                return -1;

        /* handle zero-length case */
        if (maxgroups <= 0) {
                *grpcnt = 0;
                return -1;
        }

        /* copy primary group */
        groups[ngroups++] = pgid;

        /* copy each entry from getgrset into group list */
        while ((grp = strsep(&grplist, ",")) != NULL) {
                ll = strtoll(grp, NULL, 10);
                if (ngroups >= maxgroups || ll < 0 || ll > UID_MAX) {
                        ret = -1;
                        goto out;
                }
                gid = (gid_t)ll;
                if (gid == pgid)
                        continue;       /* we have already added primary gid */
                groups[ngroups++] = gid;
        }
out:
        free(cp);
        *grpcnt = ngroups;
        return ret;
}
# endif /* USE_GETGRSET */

#endif /* _AIX */