File openssh-6.6p1-sftp_homechroot.patch of Package openssh.3552

Overview Repositories Revisions Requests Users Attributes Meta

File openssh-6.6p1-sftp_homechroot.patch of Package openssh.3552

# HG changeset patch
# Parent  882f0f59d303e249dd46ee8a42b1e4fb4d1df02a
# run sftp sessions inside a chroot

diff --git a/openssh-6.6p1/session.c b/openssh-6.6p1/session.c
--- a/openssh-6.6p1/session.c
+++ b/openssh-6.6p1/session.c
@@ -120,16 +120,18 @@ int	do_exec(Session *, const char *);
 void	do_login(Session *, const char *);
 #ifdef LOGIN_NEEDS_UTMPX
 static void	do_pre_login(Session *s);
 #endif
 void	do_child(Session *, const char *);
 void	do_motd(void);
 int	check_quietlogin(Session *, const char *);
 
+int	chroot_no_tree = 0;
+
 static void do_authenticated1(Authctxt *);
 static void do_authenticated2(Authctxt *);
 
 static int session_pty_req(Session *);
 
 /* import */
 extern ServerOptions options;
 extern char *__progname;
@@ -829,16 +831,21 @@ do_exec(Session *s, const char *command)
 		    "subsystem '%.900s'", s->subsys);
 	} else if (command == NULL) {
 		snprintf(session_type, sizeof(session_type), "shell");
 	} else {
 		/* NB. we don't log unforced commands to preserve privacy */
 		snprintf(session_type, sizeof(session_type), "command");
 	}
 
+	if ((s->is_subsystem != SUBSYSTEM_INT_SFTP) && chroot_no_tree) {
+		logit("You aren't welcomed, go away!");
+		exit (1);
+	}
+
 	if (s->ttyfd != -1) {
 		tty = s->tty;
 		if (strncmp(tty, "/dev/", 5) == 0)
 			tty += 5;
 	}
 
 	verbose("Starting session: %s%s%s for %s from %.200s port %d",
 	    session_type,
@@ -1465,67 +1472,132 @@ do_nologin(struct passwd *pw)
  		while (fgets(buf, sizeof(buf), f))
  			fputs(buf, stderr);
  		fclose(f);
  	}
 	exit(254);
 }
 
 /*
+ * Test if filesystem is mounted nosuid and nodev
+ */
+
+static void
+test_nosuid (char * path, dev_t fs)
+{
+	FILE *f;
+	struct stat st;
+	char buf[4096], *s, *on, *mountpoint, *opt;
+	int nodev, nosuid;
+
+	if (!(f = popen ("/bin/mount", "r")))
+		fatal ("%s: popen(\"/bin/mount\", \"r\"): %s",
+		    __func__, strerror (errno));
+	for (;;) {
+		s = fgets (buf, sizeof (buf), f);
+		if (ferror (f))
+			fatal ("%s: read from popen: %s", __func__,
+			    strerror (errno));
+		if (!s) {
+			pclose (f);
+			fatal ("cannot find filesystem with the chroot directory");
+		}
+		(void) strtok (buf, " ");
+		on = strtok (NULL, " ");
+		if (strcmp (on, "on")) {
+			pclose (f);
+			fatal ("bad format of mount output");
+		}
+		mountpoint = strtok (NULL, " ");
+		if (memcmp (path, mountpoint, strlen (mountpoint)))
+			continue;
+		if (stat(mountpoint, &st) != 0) {
+			pclose (f);
+			fatal("%s: stat(\"%s\"): %s", __func__,
+			    mountpoint, strerror(errno));
+		}
+		if (fs != st.st_dev)
+			continue;
+		nodev = nosuid = 0;
+		for (opt = strtok (NULL, "("); opt; opt = strtok (NULL, " ,)")) {
+			if (!strcmp (opt, "nodev"))
+				nodev = 1;
+			else if (!strcmp (opt, "nosuid"))
+				nosuid = 1;
+			else if (!strcmp (opt, "noexec"))
+				nosuid = 1;
+			if (nodev && nosuid) {
+				pclose (f);
+				return;
+			}
+		}
+		fatal ("chroot into directory without nodev and either noexec or nosuid");
+	}
+}
+
+/*
  * Chroot into a directory after checking it for safety: all path components
  * must be root-owned directories with strict permissions.
  */
 static void
 safely_chroot(const char *path, uid_t uid)
 {
 	const char *cp;
 	char component[MAXPATHLEN];
 	struct stat st;
+	int last;
 
 	if (*path != '/')
 		fatal("chroot path does not begin at root");
 	if (strlen(path) >= sizeof(component))
 		fatal("chroot path too long");
 
 	/*
 	 * Descend the path, checking that each component is a
 	 * root-owned directory with strict permissions.
 	 */
 	for (cp = path; cp != NULL;) {
-		if ((cp = strchr(cp, '/')) == NULL)
+		if (((last = ((cp = strchr(cp, '/')) == NULL))))
 			strlcpy(component, path, sizeof(component));
 		else {
 			cp++;
 			memcpy(component, path, cp - path);
 			component[cp - path] = '\0';
 		}
 	
 		debug3("%s: checking '%s'", __func__, component);
 
 		if (stat(component, &st) != 0)
 			fatal("%s: stat(\"%s\"): %s", __func__,
 			    component, strerror(errno));
-		if (st.st_uid != 0 || (st.st_mode & 022) != 0)
+		if ((st.st_uid != 0 || (st.st_mode & 022) != 0) && !(last && st.st_uid == uid))
 			fatal("bad ownership or modes for chroot "
 			    "directory %s\"%s\"", 
 			    cp == NULL ? "" : "component ", component);
 		if (!S_ISDIR(st.st_mode))
 			fatal("chroot path %s\"%s\" is not a directory",
 			    cp == NULL ? "" : "component ", component);
-
+	}
+	setenv ("TZ", "/etc/localtime", 0);
+	tzset();
+
+	if (st.st_uid) {
+		test_nosuid(path, st.st_dev);
+		++chroot_no_tree;
 	}
 
 	if (chdir(path) == -1)
 		fatal("Unable to chdir to chroot path \"%s\": "
 		    "%s", path, strerror(errno));
 	if (chroot(path) == -1)
 		fatal("chroot(\"%s\"): %s", path, strerror(errno));
 	if (chdir("/") == -1)
 		fatal("%s: chdir(/) after chroot: %s",
 		    __func__, strerror(errno));
+
 	verbose("Changed root directory to \"%s\"", path);
 }
 
 /* Set login name, uid, gid, and groups. */
 void
 do_setusercontext(struct passwd *pw)
 {
 	char *chroot_path, *tmp;
diff --git a/openssh-6.6p1/sftp-chrootenv.h b/openssh-6.6p1/sftp-chrootenv.h
new file mode 100644
--- /dev/null
+++ b/openssh-6.6p1/sftp-chrootenv.h
@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2009 Jan F Chadima.  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.
+ */
+#ifndef CHROOTENV_H
+#define CHROOTENV_H
+
+extern int	chroot_no_tree;
+
+#endif
+
diff --git a/openssh-6.6p1/sftp-common.c b/openssh-6.6p1/sftp-common.c
--- a/openssh-6.6p1/sftp-common.c
+++ b/openssh-6.6p1/sftp-common.c
@@ -42,16 +42,17 @@
 #endif
 
 #include "xmalloc.h"
 #include "buffer.h"
 #include "log.h"
 
 #include "sftp.h"
 #include "sftp-common.h"
+#include "sftp-chrootenv.h"
 
 /* Clear contents of attributes structure */
 void
 attrib_clear(Attrib *a)
 {
 	a->flags = 0;
 	a->size = 0;
 	a->uid = 0;
@@ -193,23 +194,23 @@ ls_file(const char *name, const struct s
 	int ulen, glen, sz = 0;
 	struct tm *ltime = localtime(&st->st_mtime);
 	char *user, *group;
 	char buf[1024], mode[11+1], tbuf[12+1], ubuf[11+1], gbuf[11+1];
 	char sbuf[FMT_SCALED_STRSIZE];
 	time_t now;
 
 	strmode(st->st_mode, mode);
-	if (!remote) {
+	if (!remote && !chroot_no_tree) {
 		user = user_from_uid(st->st_uid, 0);
 	} else {
 		snprintf(ubuf, sizeof ubuf, "%u", (u_int)st->st_uid);
 		user = ubuf;
 	}
-	if (!remote) {
+	if (!remote && !chroot_no_tree) {
 		group = group_from_gid(st->st_gid, 0);
 	} else {
 		snprintf(gbuf, sizeof gbuf, "%u", (u_int)st->st_gid);
 		group = gbuf;
 	}
 	if (ltime != NULL) {
 		now = time(NULL);
 		if (now - (365*24*60*60)/2 < st->st_mtime &&
diff --git a/openssh-6.6p1/sftp-server-main.c b/openssh-6.6p1/sftp-server-main.c
--- a/openssh-6.6p1/sftp-server-main.c
+++ b/openssh-6.6p1/sftp-server-main.c
@@ -17,21 +17,24 @@
 
 #include "includes.h"
 
 #include <sys/types.h>
 #include <pwd.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <unistd.h>
+#include <time.h>
 
 #include "log.h"
 #include "sftp.h"
 #include "misc.h"
 
+int chroot_no_tree = 0;
+
 void
 cleanup_exit(int i)
 {
 	sftp_server_cleanup_exit(i);
 }
 
 int
 main(int argc, char **argv)
diff --git a/openssh-6.6p1/sftp.c b/openssh-6.6p1/sftp.c
--- a/openssh-6.6p1/sftp.c
+++ b/openssh-6.6p1/sftp.c
@@ -109,16 +109,18 @@ struct complete_ctx {
 	char **remote_pathp;
 };
 
 int remote_glob(struct sftp_conn *, const char *, int,
     int (*)(const char *, int), glob_t *); /* proto for sftp-glob.c */
 
 extern char *__progname;
 
+int chroot_no_tree = 0;
+
 /* Separators for interactive commands */
 #define WHITESPACE " \t\r\n"
 
 /* ls flags */
 #define LS_LONG_VIEW	0x0001	/* Full view ala ls -l */
 #define LS_SHORT_VIEW	0x0002	/* Single row view ala ls -1 */
 #define LS_NUMERIC_VIEW	0x0004	/* Long view with numeric uid/gid */
 #define LS_NAME_SORT	0x0008	/* Sort by name (default) */
diff --git a/openssh-6.6p1/sshd_config.0 b/openssh-6.6p1/sshd_config.0
--- a/openssh-6.6p1/sshd_config.0
+++ b/openssh-6.6p1/sshd_config.0
@@ -189,16 +189,24 @@ DESCRIPTION
              session this requires at least a shell, typically sh(1), and
              basic /dev nodes such as null(4), zero(4), stdin(4), stdout(4),
              stderr(4), arandom(4) and tty(4) devices.  For file transfer
              sessions using ``sftp'', no additional configuration of the
              environment is necessary if the in-process sftp server is used,
              though sessions which use logging do require /dev/log inside the
              chroot directory (see sftp-server(8) for details).
 
+             In the special case when only sftp is used, not ssh nor scp, it
+             is possible to use ChrootDirectory %h or ChrootDirectory
+             /some/path/%u. The file system containing this directory must be
+             mounted with options nodev and either nosuid or noexec. The owner
+             of the directory should be the user. The ownership of the other
+             components of the path must fulfill the usual conditions. No adi-
+             tional files are required to be present in the directory.
+
              The default is not to chroot(2).
 
      Ciphers
              Specifies the ciphers allowed for protocol version 2.  Multiple
              ciphers must be comma-separated.  The supported ciphers are:
 
              ``3des-cbc'', ``aes128-cbc'', ``aes192-cbc'', ``aes256-cbc'',
              ``aes128-ctr'', ``aes192-ctr'', ``aes256-ctr'',
diff --git a/openssh-6.6p1/sshd_config.5 b/openssh-6.6p1/sshd_config.5
--- a/openssh-6.6p1/sshd_config.5
+++ b/openssh-6.6p1/sshd_config.5
@@ -324,16 +324,27 @@ For file transfer sessions using
 no additional configuration of the environment is necessary if the
 in-process sftp server is used,
 though sessions which use logging do require
 .Pa /dev/log
 inside the chroot directory (see
 .Xr sftp-server 8
 for details).
 .Pp
+In the special case when only sftp is used, not ssh nor scp,
+it is possible to use
+.Cm ChrootDirectory
+%h or
+.Cm ChrootDirectory
+/some/path/%u. The file system containing this directory must be
+mounted with options nodev and either nosuid or noexec. The owner of the
+directory should be the user. The ownership of the other components of the path
+must fulfill the usual conditions. No aditional files are required to be present
+in the directory.
+.Pp
 The default is not to
 .Xr chroot 2 .
 .It Cm Ciphers
 Specifies the ciphers allowed for protocol version 2.
 Multiple ciphers must be comma-separated.
 The supported ciphers are:
 .Pp
 .Dq 3des-cbc ,

Places

File openssh-6.6p1-sftp_homechroot.patch of Package openssh.3552

Places