Date: Mon, 26 May 1997 13:26:18 +0400 (MSD) From: Dmitry Mishin <Dmitry.Mishin@wplus.net> To: mrcpu@cdsnet.net (Jaye Mathisen) Cc: hackers@FreeBSD.ORG Subject: Re: Correct way to chroot for shell account users? Message-ID: <199705260926.NAA24621@himera.wplus.net> In-Reply-To: <Pine.NEB.3.95.970525144745.28807A-100000@mail.cdsnet.net> from Jaye Mathisen at "May 25, 97 02:50:55 pm"
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>
>
> Anybody got any tips on how to write a secure shell to exec on login to
> set a users environment to the "right thing".
>
> (I don't mean a rsh type secure shell, but rather a good secure thing
> to have in /etc/master.passwd that execs the real shell in a chroot'd
> environment.).
>
> Any code appreciated as well. Thanks.
>
>
>
>
All setup as in wu-ftpd + files in /chroot/./var/
Hope it can help you,
--
D.Mishin
*** /usr/src/usr.bin/login/login.c Mon Aug 28 15:15:54 1995
--- login.c Mon May 26 13:02:30 1997
***************
*** 130,135 ****
--- 130,137 ----
#ifdef SKEY
int permit_passwd = 0;
#endif
+ char *pp;
+ int is_chrooted = 0;
(void)signal(SIGALRM, timedout);
(void)alarm(timeout);
***************
*** 401,408 ****
--- 403,457 ----
initgroups(username, pwd->pw_gid);
+ if (p = strstr(pwd->pw_dir, "/./"))
+ {
+ chmod(ttyn, 0622);
+ pp = strdup(pwd->pw_dir);
+ pp[p - pwd->pw_dir] = 0;
+ if (chroot(pp)) {
+ syslog(LOG_INFO, "CHROOT error %s: %m", pwd->pw_name);
+ exit(1);
+ }
+ is_chrooted = 1;
+
+ if (!(pwd = getpwnam(username)))
+ {
+ syslog(LOG_INFO, "CHROOT user %s isn't defined", username);
+ exit(1);
+ }
+
+
+ /* Nothing else left to fail -- really log in. */
+ memset((void *)&utmp, 0, sizeof(utmp));
+ (void)time(&utmp.ut_time);
+ (void)strncpy(utmp.ut_name, username, sizeof(utmp.ut_name));
+ if (hostname)
+ (void)strncpy(utmp.ut_host, hostname, sizeof(utmp.ut_host));
+ (void)strncpy(utmp.ut_line, tty, sizeof(utmp.ut_line));
+ login(&utmp);
+
+ dolastlog(quietlog);
+
+ /*
+ * Set device protections, depending on what terminal the
+ * user is logged in. This feature is used on Suns to give
+ * console users better privacy.
+ */
+ login_fbtab(tty, pwd->pw_uid, pwd->pw_gid);
+
+ (void)chown(ttyn, pwd->pw_uid,
+ (gr = getgrnam(TTYGRPNAME)) ? gr->gr_gid : pwd->pw_gid);
+
+
+ (void)setgid(pwd->pw_gid);
+
+ initgroups(username, pwd->pw_gid);
+
+ }
+
if (*pwd->pw_shell == '\0')
pwd->pw_shell = _PATH_BSHELL;
+
/* Destroy environment unless user has requested its preservation. */
if (!pflag)
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