4ad359ccc6
If a user has home directory "/" and login shell "*" then login and su enter an endless loop by constantly switching to the next subsystem. This could also be achieved with a layered approach so just checking for "/" as home directory is not enough to protect against such a misconfiguration. Just break the loop if it progressed too far. I doubt that this has negative impact on any real setup. Signed-off-by: Samanta Navarro <ferivoz@riseup.net>
70 lines
1.7 KiB
C
70 lines
1.7 KiB
C
/*
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* SPDX-FileCopyrightText: 1989 - 1991, Julianne Frances Haugh
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* SPDX-FileCopyrightText: 1996 - 1999, Marek Michałkiewicz
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* SPDX-FileCopyrightText: 2003 - 2006, Tomasz Kłoczko
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <config.h>
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#ident "$Id$"
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#include <pwd.h>
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#include <stdio.h>
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#include <sys/types.h>
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#include "prototypes.h"
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#include "defines.h"
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#define MAX_SUBROOT2 "maximum subsystem depth reached\n"
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#define BAD_SUBROOT2 "invalid root `%s' for user `%s'\n"
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#define NO_SUBROOT2 "no subsystem root `%s' for user `%s'\n"
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#define MAX_DEPTH 1024
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/*
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* subsystem - change to subsystem root
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*
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* A subsystem login is indicated by the presence of a "*" as
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* the first character of the login shell. The given home
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* directory will be used as the root of a new filesystem which
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* the user is actually logged into.
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*/
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void subsystem (const struct passwd *pw)
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{
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static int depth = 0;
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/*
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* Prevent endless loop on misconfigured systems.
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*/
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if (++depth > MAX_DEPTH) {
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printf (_("Maximum subsystem depth reached\n"));
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SYSLOG ((LOG_WARN, MAX_SUBROOT2));
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closelog ();
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exit (EXIT_FAILURE);
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}
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/*
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* The new root directory must begin with a "/" character.
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*/
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if (pw->pw_dir[0] != '/') {
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printf (_("Invalid root directory '%s'\n"), pw->pw_dir);
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SYSLOG ((LOG_WARN, BAD_SUBROOT2, pw->pw_dir, pw->pw_name));
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closelog ();
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exit (EXIT_FAILURE);
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}
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/*
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* The directory must be accessible and the current process
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* must be able to change into it.
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*/
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if ( (chdir (pw->pw_dir) != 0)
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|| (chroot (pw->pw_dir) != 0)) {
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(void) printf (_("Can't change root directory to '%s'\n"),
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pw->pw_dir);
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SYSLOG ((LOG_WARN, NO_SUBROOT2, pw->pw_dir, pw->pw_name));
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closelog ();
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exit (EXIT_FAILURE);
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}
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}
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