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Add check for nosuid, nodev in homechroot

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This commit is contained in:
Jan F. Chadima 2009-09-07 10:20:22 +00:00
parent 49d0cf7e60
commit 257d66a4fb
2 changed files with 122 additions and 18 deletions
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135
openssh-5.2p1-homechroot.patch
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@ -1,6 +1,6 @@
diff -up /dev/null openssh-5.2p1/chrootenv.h
--- /dev/null 2009-07-23 14:57:23.604046842 +0200
+++ openssh-5.2p1/chrootenv.h 2009-07-24 07:11:29.000000000 +0200
--- /dev/null 2009-08-19 20:21:50.796466837 +0200
+++ openssh-5.2p1/chrootenv.h 2009-08-19 23:22:15.000000000 +0200
@@ -0,0 +1,32 @@
+/* $OpenBSD: session.h,v 1.30 2008/05/08 12:21:16 djm Exp $ */
+
@ -35,8 +35,8 @@ diff -up /dev/null openssh-5.2p1/chrootenv.h
+#endif
+
diff -up openssh-5.2p1/session.c.homechroot openssh-5.2p1/session.c
--- openssh-5.2p1/session.c.homechroot 2009-07-24 07:11:22.000000000 +0200
+++ openssh-5.2p1/session.c 2009-07-24 07:33:14.000000000 +0200
--- openssh-5.2p1/session.c.homechroot 2009-08-19 23:22:14.000000000 +0200
+++ openssh-5.2p1/session.c 2009-08-19 23:22:15.000000000 +0200
@@ -119,6 +119,8 @@ void do_child(Session *, const char *);
void do_motd(void);
int check_quietlogin(Session *, const char *);
@ -58,7 +58,69 @@ diff -up openssh-5.2p1/session.c.homechroot openssh-5.2p1/session.c
#ifdef SSH_AUDIT_EVENTS
if (command != NULL)
PRIVSEP(audit_run_command(command));
@@ -1408,6 +1415,7 @@ safely_chroot(const char *path, uid_t ui
@@ -1399,6 +1406,61 @@ do_nologin(struct passwd *pw)
}
/*
+ * Test if filesystem is mounted nosuid and nodev
+ */
+
+static void
+test_nosuid (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 found 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 (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 or nosuid");
+ }
+}
+
+/*
* Chroot into a directory after checking it for safety: all path components
* must be root-owned directories with strict permissions.
*/
@@ -1408,6 +1470,7 @@ safely_chroot(const char *path, uid_t ui
const char *cp;
char component[MAXPATHLEN];
struct stat st;
@ -66,7 +128,7 @@ diff -up openssh-5.2p1/session.c.homechroot openssh-5.2p1/session.c
if (*path != '/')
fatal("chroot path does not begin at root");
@@ -1419,7 +1427,7 @@ safely_chroot(const char *path, uid_t ui
@@ -1419,7 +1482,7 @@ safely_chroot(const char *path, uid_t ui
* root-owned directory with strict permissions.
*/
for (cp = path; cp != NULL;) {
@ -75,7 +137,7 @@ diff -up openssh-5.2p1/session.c.homechroot openssh-5.2p1/session.c
strlcpy(component, path, sizeof(component));
else {
cp++;
@@ -1432,15 +1440,19 @@ safely_chroot(const char *path, uid_t ui
@@ -1432,14 +1495,20 @@ safely_chroot(const char *path, uid_t ui
if (stat(component, &st) != 0)
fatal("%s: stat(\"%s\"): %s", __func__,
component, strerror(errno));
@ -87,30 +149,30 @@ diff -up openssh-5.2p1/session.c.homechroot openssh-5.2p1/session.c
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 != uid)
+ if (st.st_uid) {
+ test_nosuid (st.st_dev);
+ ++chroot_no_tree;
}
if (chdir(path) == -1)
fatal("Unable to chdir to chroot path \"%s\": "
@@ -1451,6 +1463,10 @@ safely_chroot(const char *path, uid_t ui
@@ -1451,6 +1520,10 @@ safely_chroot(const char *path, uid_t ui
if (chdir("/") == -1)
fatal("%s: chdir(/) after chroot: %s",
__func__, strerror(errno));
+
+ if (access ("/etc/localtime", R_OK) < 0)
+ ++chroot_no_tree;
+ ++chroot_no_tree;
+
verbose("Changed root directory to \"%s\"", path);
}
diff -up openssh-5.2p1/sftp.c.homechroot openssh-5.2p1/sftp.c
--- openssh-5.2p1/sftp.c.homechroot 2009-02-14 06:26:19.000000000 +0100
+++ openssh-5.2p1/sftp.c 2009-07-24 07:11:29.000000000 +0200
+++ openssh-5.2p1/sftp.c 2009-08-19 23:22:15.000000000 +0200
@@ -94,6 +94,8 @@ int remote_glob(struct sftp_conn *, cons
extern char *__progname;
@ -122,7 +184,7 @@ diff -up openssh-5.2p1/sftp.c.homechroot openssh-5.2p1/sftp.c
diff -up openssh-5.2p1/sftp-common.c.homechroot openssh-5.2p1/sftp-common.c
--- openssh-5.2p1/sftp-common.c.homechroot 2006-08-05 04:39:40.000000000 +0200
+++ openssh-5.2p1/sftp-common.c 2009-07-24 07:11:29.000000000 +0200
+++ openssh-5.2p1/sftp-common.c 2009-08-19 23:22:15.000000000 +0200
@@ -40,6 +40,7 @@
#include "xmalloc.h"
#include "buffer.h"
@ -149,7 +211,7 @@ diff -up openssh-5.2p1/sftp-common.c.homechroot openssh-5.2p1/sftp-common.c
snprintf(gbuf, sizeof gbuf, "%u", (u_int)st->st_gid);
diff -up openssh-5.2p1/sftp-server-main.c.homechroot openssh-5.2p1/sftp-server-main.c
--- openssh-5.2p1/sftp-server-main.c.homechroot 2009-02-21 22:47:02.000000000 +0100
+++ openssh-5.2p1/sftp-server-main.c 2009-07-24 07:11:29.000000000 +0200
+++ openssh-5.2p1/sftp-server-main.c 2009-08-19 23:22:15.000000000 +0200
@@ -22,11 +22,14 @@
#include <stdarg.h>
#include <stdio.h>
@ -165,3 +227,42 @@ diff -up openssh-5.2p1/sftp-server-main.c.homechroot openssh-5.2p1/sftp-server-m
void
cleanup_exit(int i)
{
diff -up openssh-5.2p1/sshd_config.0.homechroot openssh-5.2p1/sshd_config.0
--- openssh-5.2p1/sshd_config.0.homechroot 2009-08-19 23:22:14.000000000 +0200
+++ openssh-5.2p1/sshd_config.0 2009-08-19 23:31:26.000000000 +0200
@@ -112,6 +112,14 @@ DESCRIPTION
essary if the in-process sftp server is used (see Subsystem 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
diff -up openssh-5.2p1/sshd_config.5.homechroot openssh-5.2p1/sshd_config.5
--- openssh-5.2p1/sshd_config.5.homechroot 2009-08-19 23:22:14.000000000 +0200
+++ openssh-5.2p1/sshd_config.5 2009-08-19 23:22:15.000000000 +0200
@@ -219,6 +219,17 @@ in-process sftp server is used (see
.Cm Subsystem
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

5
openssh.spec
View File

@ -63,7 +63,7 @@
Summary: An open source implementation of SSH protocol versions 1 and 2
Name: openssh
Version: 5.2p1
Release: 23%{?dist}%{?rescue_rel}
Release: 24%{?dist}%{?rescue_rel}
URL: http://www.openssh.com/portable.html
#Source0: ftp://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-%{version}.tar.gz
#Source1: ftp://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-%{version}.tar.gz.asc
@ -468,6 +468,9 @@ fi
%endif
%changelog
* Mon Sep 7 2009 Jan F. Chadima <jchadima@redhat.com> - 5.2p1-24
- Add check for nosuid, nodev in homechroot
* Tue Sep 1 2009 Jan F. Chadima <jchadima@redhat.com> - 5.2p1-23
- add correct patch for ip-opts