[Buildroot] [PATCH 2/4] package/openssh: improve integration for systemd

Norbert Lange nolange79 at gmail.com
Thu Jun 11 00:04:46 UTC 2020


Am So., 7. Juni 2020 um 21:42 Uhr schrieb Jérémy ROSEN <jeremy.rosen at smile.fr>:
>
>
>
> Le dim. 7 juin 2020 à 21:24, Norbert Lange <nolange79 at gmail.com> a écrit :
>>
>> Am So., 7. Juni 2020 um 21:16 Uhr schrieb Jérémy ROSEN <jeremy.rosen at smile.fr>:
>> >
>> >
>> >
>> > Le dim. 7 juin 2020 à 21:03, Norbert Lange <nolange79 at gmail.com> a écrit :
>> >>
>> >> Am So., 7. Juni 2020 um 12:54 Uhr schrieb Jérémy ROSEN <jeremy.rosen at smile.fr>:
>> >> >
>> >> >
>> >> >
>> >> > Le sam. 6 juin 2020 à 00:59, Norbert Lange <nolange79 at gmail.com> a écrit :
>> >> >>
>> >> >> the openssh daemon is not suited for systemd's simple
>> >> >> service type. dependend services should only start
>> >> >> when sshd is ready to accept connections.
>> >> >>
>> >> >> A patch is added from debian to allow openssh
>> >> >> to communicate this state.
>> >> >>
>> >> >> Restarts are prevented if the reason is a faulty
>> >> >> config file (errocode 255).
>> >> >>
>> >> >> The "user confinement directory" is changed to
>> >> >> '/run/sshd' which is automatically managed by systemd.
>> >> >>
>> >> >> Signed-off-by: Norbert Lange <nolange79 at gmail.com>
>> >> >> ---
>> >> >>  package/openssh/00-systemd-readiness.patch | 84 ++++++++++++++++++++++
>> >> >>  package/openssh/openssh.mk                 | 14 +++-
>> >> >>  package/openssh/sshd-sysusers.conf         |  2 +-
>> >> >>  package/openssh/sshd.service               | 13 +++-
>> >> >>  4 files changed, 109 insertions(+), 4 deletions(-)
>> >> >>  create mode 100644 package/openssh/00-systemd-readiness.patch
>> >> >>
>> >> >> diff --git a/package/openssh/00-systemd-readiness.patch b/package/openssh/00-systemd-readiness.patch
>> >> >> new file mode 100644
>> >> >> index 0000000000..be3b6b0074
>> >> >> --- /dev/null
>> >> >> +++ b/package/openssh/00-systemd-readiness.patch
>> >> >> @@ -0,0 +1,84 @@
>> >> >> +From ab765b2bd55062a704f09da8f8c1c4ad1d6630a7 Mon Sep 17 00:00:00 2001
>> >> >> +From: Michael Biebl <biebl at debian.org>
>> >> >> +Date: Mon, 21 Dec 2015 16:08:47 +0000
>> >> >> +Subject: Add systemd readiness notification support
>> >> >> +
>> >> >> +Bug-Debian: https://bugs.debian.org/778913
>> >> >> +Forwarded: no
>> >> >> +Last-Update: 2017-08-22
>> >> >> +
>> >> >> +Patch-Name: systemd-readiness.patch
>> >> >> +---
>> >> >> + configure.ac | 24 ++++++++++++++++++++++++
>> >> >> + sshd.c       |  9 +++++++++
>> >> >> + 2 files changed, 33 insertions(+)
>> >> >> +
>> >> >> +diff --git a/configure.ac b/configure.ac
>> >> >> +index e894db9fc..c119d6fd1 100644
>> >> >> +--- a/configure.ac
>> >> >> ++++ b/configure.ac
>> >> >> +@@ -4499,6 +4499,29 @@ AC_ARG_WITH([kerberos5],
>> >> >> + AC_SUBST([GSSLIBS])
>> >> >> + AC_SUBST([K5LIBS])
>> >> >> +
>> >> >> ++# Check whether user wants systemd support
>> >> >> ++SYSTEMD_MSG="no"
>> >> >> ++AC_ARG_WITH(systemd,
>> >> >> ++      [  --with-systemd          Enable systemd support],
>> >> >> ++      [ if test "x$withval" != "xno" ; then
>> >> >> ++              AC_PATH_TOOL([PKGCONFIG], [pkg-config], [no])
>> >> >> ++              if test "$PKGCONFIG" != "no"; then
>> >> >> ++                      AC_MSG_CHECKING([for libsystemd])
>> >> >> ++                      if $PKGCONFIG --exists libsystemd; then
>> >> >> ++                              SYSTEMD_CFLAGS=`$PKGCONFIG --cflags libsystemd`
>> >> >> ++                              SYSTEMD_LIBS=`$PKGCONFIG --libs libsystemd`
>> >> >> ++                              CPPFLAGS="$CPPFLAGS $SYSTEMD_CFLAGS"
>> >> >> ++                              SSHDLIBS="$SSHDLIBS $SYSTEMD_LIBS"
>> >> >> ++                              AC_MSG_RESULT([yes])
>> >> >> ++                              AC_DEFINE(HAVE_SYSTEMD, 1, [Define if you want systemd support.])
>> >> >> ++                              SYSTEMD_MSG="yes"
>> >> >> ++                      else
>> >> >> ++                              AC_MSG_RESULT([no])
>> >> >> ++                      fi
>> >> >> ++              fi
>> >> >> ++      fi ]
>> >> >> ++)
>> >> >> ++
>> >> >> + # Looking for programs, paths and files
>> >> >> +
>> >> >> + PRIVSEP_PATH=/var/empty
>> >> >> +@@ -5305,6 +5328,7 @@ echo "                   libldns support: $LDNS_MSG"
>> >> >> + echo "  Solaris process contract support: $SPC_MSG"
>> >> >> + echo "           Solaris project support: $SP_MSG"
>> >> >> + echo "         Solaris privilege support: $SPP_MSG"
>> >> >> ++echo "                   systemd support: $SYSTEMD_MSG"
>> >> >> + echo "       IP address in \$DISPLAY hack: $DISPLAY_HACK_MSG"
>> >> >> + echo "           Translate v4 in v6 hack: $IPV4_IN6_HACK_MSG"
>> >> >> + echo "                  BSD Auth support: $BSD_AUTH_MSG"
>> >> >> +diff --git a/sshd.c b/sshd.c
>> >> >> +index 4e8ff0662..5e7679a33 100644
>> >> >> +--- a/sshd.c
>> >> >> ++++ b/sshd.c
>> >> >> +@@ -85,6 +85,10 @@
>> >> >> + #include <prot.h>
>> >> >> + #endif
>> >> >> +
>> >> >> ++#ifdef HAVE_SYSTEMD
>> >> >> ++#include <systemd/sd-daemon.h>
>> >> >> ++#endif
>> >> >> ++
>> >> >> + #include "xmalloc.h"
>> >> >> + #include "ssh.h"
>> >> >> + #include "ssh2.h"
>> >> >> +@@ -1951,6 +1955,11 @@ main(int ac, char **av)
>> >> >> +                       }
>> >> >> +               }
>> >> >> +
>> >> >> ++#ifdef HAVE_SYSTEMD
>> >> >> ++              /* Signal systemd that we are ready to accept connections */
>> >> >> ++              sd_notify(0, "READY=1");
>> >> >> ++#endif
>> >> >> ++
>> >> >> +               /* Accept a connection and return in a forked child */
>> >> >> +               server_accept_loop(&sock_in, &sock_out,
>> >> >> +                   &newsock, config_s);
>> >> >> diff --git a/package/openssh/openssh.mk b/package/openssh/openssh.mk
>> >> >> index 55b917e20a..d425db1428 100644
>> >> >> --- a/package/openssh/openssh.mk
>> >> >> +++ b/package/openssh/openssh.mk
>> >> >> @@ -12,6 +12,7 @@ OPENSSH_CONF_ENV = \
>> >> >>         LD="$(TARGET_CC)" \
>> >> >>         LDFLAGS="$(TARGET_CFLAGS)" \
>> >> >>         LIBS=`$(PKG_CONFIG_HOST_BINARY) --libs openssl`
>> >> >> +OPENSSH_AUTORECONF = YES
>> >> >>  OPENSSH_CONF_OPTS = \
>> >> >>         --sysconfdir=/etc/ssh \
>> >> >>         --with-default-path=$(BR2_SYSTEM_DEFAULT_PATH) \
>> >> >> @@ -22,9 +23,20 @@ OPENSSH_CONF_OPTS = \
>> >> >>         --disable-wtmpx \
>> >> >>         --disable-strip
>> >> >>
>> >> >> +ifeq ($(BR2_PACKAGE_SYSTEMD),y)
>> >> >> +OPENSSH_DEPENDENCIES = systemd
>> >> >> +
>> >> >> +OPENSSH_CONF_OPTS += \
>> >> >> +       --with-privsep-path=/run/sshd \
>> >> >> +       --with-pid-dir=/run \
>> >> >> +       --with-systemd
>> >> >> +
>> >> >> +else
>> >> >> +
>> >> >>  define OPENSSH_PERMISSIONS
>> >> >>         /var/empty d 755 root root - - - - -
>> >> >>  endef
>> >> >
>> >> >
>> >> > Do we still need this when using systemd, or can it be commented out ?
>> >>
>> >> Not sure what you mean with "this"?
>> >> The OPENSSH_PERMISSIONS block is needed when not using systemd and it
>> >> is only active then.
>> >>
>> >
>> > my bad, I missed the enclosing ifeq()
>> >
>> >>
>> >> >
>> >> >
>> >> >>
>> >> >> +endif
>> >> >>
>> >> >>  ifeq ($(BR2_TOOLCHAIN_SUPPORTS_PIE),)
>> >> >>  OPENSSH_CONF_OPTS += --without-pie
>> >> >> @@ -72,7 +84,7 @@ define OPENSSH_INSTALL_SYSTEMD_SYSUSERS
>> >> >>  endef
>> >> >>  else
>> >> >>  define OPENSSH_USERS
>> >> >> -       sshd -1 sshd -1 * /var/empty - - SSH drop priv user
>> >> >> +       sshd -1 sshd -1 * $(if $(BR2_PACKAGE_SYSTEMD),/run/sshd,/var/empty) - - SSH drop priv user
>> >> >>  endef
>> >> >>  endif
>> >> >>
>> >> >> diff --git a/package/openssh/sshd-sysusers.conf b/package/openssh/sshd-sysusers.conf
>> >> >> index ac77aec065..303d0dbb63 100644
>> >> >> --- a/package/openssh/sshd-sysusers.conf
>> >> >> +++ b/package/openssh/sshd-sysusers.conf
>> >> >> @@ -1 +1 @@
>> >> >> -u sshd - "SSH drop priv user" /var/empty
>> >> >> +u sshd - "SSH drop priv user" /run/sshd
>> >> >> diff --git a/package/openssh/sshd.service b/package/openssh/sshd.service
>> >> >> index b5e96b3a25..715bd3f7eb 100644
>> >> >> --- a/package/openssh/sshd.service
>> >> >> +++ b/package/openssh/sshd.service
>> >> >> @@ -1,11 +1,20 @@
>> >> >>  [Unit]
>> >> >>  Description=OpenSSH server daemon
>> >> >> -After=syslog.target network.target auditd.service
>> >> >> +Documentation=man:sshd(8) man:sshd_config(5)
>> >> >> +After=network.target auditd.service
>> >> >>
>> >> >>
>> >> >>  [Service]
>> >> >>  ExecStartPre=/usr/bin/ssh-keygen -A
>> >> >> -ExecStart=/usr/sbin/sshd -D -e
>> >> >> +ExecStartPre=/usr/sbin/sshd -t
>> >> >> +ExecStart=/usr/sbin/sshd -D
>> >> >
>> >> > You droped the -e, so  you are logging to syslog
>> >> > However you droped the dependency on syslog.target earlier...
>> >> > (maybe it should be syslog.socket instead of .target, btw)
>> >>
>> >>
>> >> syslog.target is long long gone, and the syslog will be
>> >> unconditionally available
>> >> https://www.freedesktop.org/wiki/Software/systemd/syslog/
>> >>
>> >>
>> >> >
>> >> >
>> >> > how exactly do you want to log  ? (I think logging to stdout is better, it will be
>> >> > redirected to the journal.
>> >>
>> >>
>> >> stdout is not really useful if syslog is supported.
>> >>
>> > i'd go the other way round
>> >
>> > syslog is not really necessary if stdout is available,
>> > but it's a matter of taste :P so let's go your way.
>>
>> Its more the point, that Openssh already implemented syslog, and thats
>> a clear functional superset of listening to stdout.
>>
>> >
>> >>
>> >> >
>> >> >
>> >> >>
>> >> >> +ExecReload=/usr/sbin/sshd -t
>> >> >>  ExecReload=/bin/kill -HUP $MAINPID
>> >> >> +KillMode=process
>> >> >
>> >> >
>> >> > Wouldn't mixed be better here ?
>> >> > I'm not really sure what the use-case for procss is anyway...
>> >>
>> >>
>> >> I taken that from debian, I could not argue against it (there is a
>> >> long discussion which I linked above).
>> >> Can you argue *for* mixed?
>> >>
>> >
>> >
>> > I didn't see any link
>> > * process : SIGTERM and SIGKILL is sent only to MainPID
>> > * mixed : SIGTERM is sent to MainPID, SIGKILL is sent to every process in the service cgroup.
>> >
>> > This means that if all works well, they do the same thing
>> >
>> > in case the MainPID fails to properly terminate its children, process would leave children alive
>> > but mixed woul kill everybody
>> >
>> > Since we are trying to terminate the service, it makes sense to me to make sur all child process
>> > are killed.
>> >
>> > but I don't see your link so I may be missing something
>>
>> The link is in the added patch: https://bugs.debian.org/778913
>>
>> As said, I could not argue either way, but I got some respect for the
>> debian guys ;)
>>
>
> The thread does not actually discuss process vs mixed...
>
> so doesn't really help here.
> OTOH, the debian version has been vetted by mbiel which is a systemc core-maintainer.
>
> so i would go with mixed if I were to write the service from scratch, but since I don't have an
> explanation for the choice of process, I'm not entirely sure...
>
> A possibility is that ssh creates a process per connection. in that case
> * process would not kill all ongoing connections
> * mixed would
>
> maybe it was chosen to protect existing connection. that would make some sense.

Well, debian and arch seem to agree on using "process", I guess it
means to just prevent
new connections and not kill existing ones?

Can I get a "reviewed-by" for this patch, so this and #3 can be merged?

Norbert


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