On 07/13/2018 02:03 AM, [email protected] wrote:
From: Changqing Li <[email protected]>
From: Wenzong Fan <[email protected]>
The /etc/hosts.deny doesn't work for sshd without tcp-wrappers support,
apply below patch from Debian to fix it.
Signed-off-by: Changqing Li <[email protected]>
---
.../0001-Restore-TCP-wrappers-support.patch | 171 +++++++++++++++++++++
meta/recipes-connectivity/openssh/openssh_7.7p1.bb | 4 +
2 files changed, 175 insertions(+)
create mode 100644
meta/recipes-connectivity/openssh/openssh/0001-Restore-TCP-wrappers-support.patch
diff --git
a/meta/recipes-connectivity/openssh/openssh/0001-Restore-TCP-wrappers-support.patch
b/meta/recipes-connectivity/openssh/openssh/0001-Restore-TCP-wrappers-support.patch
new file mode 100644
index 0000000..5f3efa6
--- /dev/null
+++
b/meta/recipes-connectivity/openssh/openssh/0001-Restore-TCP-wrappers-support.patch
@@ -0,0 +1,171 @@
+From 03cdbc92adf763f9ff5bb89f7820f9e1734f745b Mon Sep 17 00:00:00 2001
+From: Changqing Li <[email protected]>
+Date: Fri, 13 Jul 2018 12:16:18 +0800
+Subject: [PATCH] Restore TCP wrappers support
+
+Support for TCP wrappers was dropped in OpenSSH 6.7. See this message
+and thread:
+
+ https://lists.mindrot.org/pipermail/openssh-unix-dev/2014-April/032497.html
+
+It is true that this reduces preauth attack surface in sshd. On the
+other hand, this support seems to be quite widely used, and abruptly
+dropping it (from the perspective of users who don't read
+openssh-unix-dev) could easily cause more serious problems in practice.
+
+Upstream-Status: Inappropriate
+
+This patch was imported by wenzong firstly, the following sign is not
+the origin author, just adjust it to fit for new version of openssh.
I suppose we can do this for one more release but
we shouldn't carry tcp-wrappers support [1] forever without
considering alternatives.
FYI,
Fedora has started a process to deprecate tcp-wrappers:
https://fedoraproject.org/wiki/Changes/Deprecate_TCP_wrappers
The first step is to require that individual services use the
tcp-wrapper tcpd monitor. There is (of course!) a systemd solution:
Add simple eBPF-based per-unit IP access lists and accounting
https://github.com/systemd/systemd/pull/6764
That went into v235, in October 2017.
I'm not sure what plans Debian or other distros have.
Buildroot doesn't seem to support tcp-wrappers at all.
If there are no objections to removing tcp-wrappers from oe-core
in 2.7/2.8, I will open a YP Bugzilla enhancement next week.
../Randy
[1] There are a number of packages that optionally depend
on tcp-wrappers:
oe-core:
$ rgrep -il "PACKAGECONFIG\[tcp-wrappers\]" *
meta/recipes-connectivity/nfs-utils/nfs-utils_2.3.1.bb
meta/recipes-connectivity/socat/socat_1.7.3.2.bb
meta/recipes-extended/quota/quota_4.04.bb
meta/recipes-extended/xinetd/xinetd_2.3.15.bb
meta/recipes-extended/rpcbind/rpcbind_0.2.4.bb
meta-oe:
$ rgrep -il "PACKAGECONFIG\[tcp-wrappers\]" *
meta-networking/recipes-daemons/atftp/atftp_git.bb
meta-networking/recipes-daemons/vsftpd/vsftpd_3.0.3.bb
+
+Signed-off-by: Changqing Li <[email protected]>
+
+---
+ configure.ac | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ sshd.8 | 7 +++++++
+ sshd.c | 26 ++++++++++++++++++++++++++
+ 3 files changed, 89 insertions(+)
+
+diff --git a/configure.ac b/configure.ac
+index 663062b..a2accdd 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -1542,6 +1542,61 @@ AC_ARG_WITH([skey],
+ ]
+ )
+
++#Check whether user wants TCP wrappers support
++TCPW_MSG="no"
++AC_ARG_WITH([tcp-wrappers],
++ [ --with-tcp-wrappers[[=PATH]] Enable tcpwrappers support (optionally
in PATH)],
++ [
++ if test "x$withval" != "xno" ; then
++ saved_LIBS="$LIBS"
++ saved_LDFLAGS="$LDFLAGS"
++ saved_CPPFLAGS="$CPPFLAGS"
++ if test -n "${withval}" && \
++ test "x${withval}" != "xyes"; then
++ if test -d "${withval}/lib"; then
++ if test -n "${need_dash_r}"; then
++ LDFLAGS="-L${withval}/lib
-R${withval}/lib ${LDFLAGS}"
++ else
++ LDFLAGS="-L${withval}/lib
${LDFLAGS}"
++ fi
++ else
++ if test -n "${need_dash_r}"; then
++ LDFLAGS="-L${withval} -R${withval}
${LDFLAGS}"
++ else
++ LDFLAGS="-L${withval}
${LDFLAGS}"
++ fi
++ fi
++ if test -d "${withval}/include"; then
++ CPPFLAGS="-I${withval}/include
${CPPFLAGS}"
++ else
++ CPPFLAGS="-I${withval} ${CPPFLAGS}"
++ fi
++ fi
++ LIBS="-lwrap $LIBS"
++ AC_MSG_CHECKING([for libwrap])
++ AC_LINK_IFELSE([AC_LANG_PROGRAM([[
++#include <sys/types.h>
++#include <sys/socket.h>
++#include <netinet/in.h>
++#include <tcpd.h>
++int deny_severity = 0, allow_severity = 0;
++ ]], [[
++ hosts_access(0);
++ ]])], [
++ AC_MSG_RESULT([yes])
++ AC_DEFINE([LIBWRAP], [1],
++ [Define if you want
++ TCP Wrappers support])
++ SSHDLIBS="$SSHDLIBS -lwrap"
++ TCPW_MSG="yes"
++ ], [
++ AC_MSG_ERROR([*** libwrap missing])
++ ])
++ LIBS="$saved_LIBS"
++ fi
++ ]
++)
++
+ # Check whether user wants to use ldns
+ LDNS_MSG="no"
+ AC_ARG_WITH(ldns,
+@@ -5216,6 +5271,7 @@ echo " OSF SIA support: $SIA_MSG"
+ echo " KerberosV support: $KRB5_MSG"
+ echo " SELinux support: $SELINUX_MSG"
+ echo " S/KEY support: $SKEY_MSG"
++echo " TCP Wrappers support: $TCPW_MSG"
+ echo " MD5 password support: $MD5_MSG"
+ echo " libedit support: $LIBEDIT_MSG"
+ echo " libldns support: $LDNS_MSG"
+diff --git a/sshd.8 b/sshd.8
+index 968ba66..c8299d5 100644
+--- a/sshd.8
++++ b/sshd.8
+@@ -845,6 +845,12 @@ the user's home directory becomes accessible.
+ This file should be writable only by the user, and need not be
+ readable by anyone else.
+ .Pp
++.It Pa /etc/hosts.allow
++.It Pa /etc/hosts.deny
++Access controls that should be enforced by tcp-wrappers are defined here.
++Further details are described in
++.Xr hosts_access 5 .
++.Pp
+ .It Pa /etc/hosts.equiv
+ This file is for host-based authentication (see
+ .Xr ssh 1 ) .
+@@ -947,6 +953,7 @@ The content of this file is not sensitive; it can be
world-readable.
+ .Xr ssh-keygen 1 ,
+ .Xr ssh-keyscan 1 ,
+ .Xr chroot 2 ,
++.Xr hosts_access 5 ,
+ .Xr login.conf 5 ,
+ .Xr moduli 5 ,
+ .Xr sshd_config 5 ,
+diff --git a/sshd.c b/sshd.c
+index fd95b68..82607d8 100644
+--- a/sshd.c
++++ b/sshd.c
+@@ -123,6 +123,13 @@
+ #include "version.h"
+ #include "ssherr.h"
+
++#ifdef LIBWRAP
++#include <tcpd.h>
++#include <syslog.h>
++int allow_severity;
++int deny_severity;
++#endif /* LIBWRAP */
++
+ /* Re-exec fds */
+ #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
+ #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
+@@ -2036,6 +2043,25 @@ main(int ac, char **av)
+ audit_connection_from(remote_ip, remote_port);
+ #endif
+
++#ifdef LIBWRAP
++ allow_severity = options.log_facility|LOG_INFO;
++ deny_severity = options.log_facility|LOG_WARNING;
++ /* Check whether logins are denied from this host. */
++ if (packet_connection_is_on_socket()) {
++ struct request_info req;
++
++ request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
++ fromhost(&req);
++
++ if (!hosts_access(&req)) {
++ debug("Connection refused by tcp wrapper");
++ refuse(&req);
++ /* NOTREACHED */
++ fatal("libwrap refuse returns");
++ }
++ }
++#endif /* LIBWRAP */
++
+ rdomain = ssh_packet_rdomain_in(ssh);
+
+ /* Log the connection. */
diff --git a/meta/recipes-connectivity/openssh/openssh_7.7p1.bb
b/meta/recipes-connectivity/openssh/openssh_7.7p1.bb
index b3da5f6..0696587 100644
--- a/meta/recipes-connectivity/openssh/openssh_7.7p1.bb
+++ b/meta/recipes-connectivity/openssh/openssh_7.7p1.bb
@@ -26,6 +26,7 @@ SRC_URI =
"http://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-${PV}.tar
file://sshd_check_keys \
file://add-test-support-for-busybox.patch \
file://disable-ciphers-not-supported-by-OpenSSL-DES.patch \
+ file://0001-Restore-TCP-wrappers-support.patch \
"
PAM_SRC_URI = "file://sshd"
@@ -61,6 +62,9 @@ EXTRA_OECONF = "'LOGIN_PROGRAM=${base_bindir}/login' \
# musl doesn't implement wtmp/utmp
EXTRA_OECONF_append_libc-musl = " --disable-wtmp"
+PACKAGECONFIG ??= "tcp-wrappers"
+PACKAGECONFIG[tcp-wrappers] = "--with-tcp-wrappers,,tcp-wrappers"
+
# Since we do not depend on libbsd, we do not want configure to use it
# just because it finds libutil.h. But, specifying --disable-libutil
# causes compile errors, so...
--
# Randy MacLeod
# Wind River Linux
--
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