6491fef1e0
OpenSSH and coreutils' chroot call chroot first and then chdir. Doing it this way is a bit safer because otherwise something could happen between chdir and chroot to the specified path (like exchange of links) so the working directory would not end up within the chroot environment. This is a purely defensive measure. 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 ( (chroot (pw->pw_dir) != 0)
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|| (chdir ("/") != 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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