[Buildroot] [PATCH 2/4] package/openssh: improve integration for systemd
Jérémy ROSEN
jeremy.rosen at smile.fr
Sun Jun 7 19:42:21 UTC 2020
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.
> Norbert
>
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