Merging debian version 241-7~deb10u9.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 180 insertions, 0 deletions

diff --git a/debian/patches/0004-pager-make-pager-secure-when-under-euid-is-changed-o.patch b/debian/patches/0004-pager-make-pager-secure-when-under-euid-is-changed-o.patch
new file mode 100644
index 0000000..6138f80
--- /dev/null
+++ b/debian/patches/0004-pager-make-pager-secure-when-under-euid-is-changed-o.patch
@@ -0,0 +1,180 @@
+From d8510d35c857547ddb601a988545ccb9a1e43fcc Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
+Date: Wed, 7 Oct 2020 11:15:05 +0200
+Subject: pager: make pager secure when under euid is changed or explicitly
+ requested
+
+The variable is renamed to SYSTEMD_PAGERSECURE (because it's not just about
+less now), and we automatically enable secure mode in certain cases, but not
+otherwise.
+
+This approach is more nuanced, but should provide a better experience for
+users:
+
+- Previusly we would set LESSSECURE=1 and trust the pager to make use of
+  it. But this has an effect only on less. We need to not start pagers which
+  are insecure when in secure mode. In particular more is like that and is a
+  very popular pager.
+
+- We don't enable secure mode always, which means that those other pagers can
+  reasonably used.
+
+- We do the right thing by default, but the user has ultimate control by
+  setting SYSTEMD_PAGERSECURE.
+
+Fixes #5666.
+
+v2:
+- also check $PKEXEC_UID
+
+v3:
+- use 'sd_pid_get_owner_uid() != geteuid()' as the condition
+---
+ man/less-variables.xml | 30 ++++++++++++++++----
+ src/shared/pager.c     | 63 ++++++++++++++++++++++++++++--------------
+ 2 files changed, 66 insertions(+), 27 deletions(-)
+
+diff --git a/man/less-variables.xml b/man/less-variables.xml
+index fed4178b01..b892854509 100644
+--- a/man/less-variables.xml
++++ b/man/less-variables.xml
+@@ -61,12 +61,30 @@
+     </varlistentry>
+ 
+     <varlistentry id='lesssecure'>
+-      <term><varname>$SYSTEMD_LESSSECURE</varname></term>
+-
+-      <listitem><para>Takes a boolean argument. Overrides the <varname>$LESSSECURE</varname> environment
+-      variable when invoking the pager, which controls the "secure" mode of less (which disables commands
+-      such as <literal>|</literal> which allow to easily shell out to external command lines). By default
+-      less secure mode is enabled, with this setting it may be disabled.</para></listitem>
++      <term><varname>$SYSTEMD_PAGERSECURE</varname></term>
++
++      <listitem><para>Takes a boolean argument. When true, the "secure" mode of the pager is enabled; if
++      false, disabled. If <varname>$SYSTEMD_PAGERSECURE</varname> is not set at all, secure mode is enabled
++      if the effective UID is not the same as the owner of the login session, see <citerefentry
++      project='man-pages'><refentrytitle>geteuid</refentrytitle><manvolnum>2</manvolnum></citerefentry> and
++      <citerefentry><refentrytitle>sd_pid_get_owner_uid</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
++      In secure mode, <option>LESSSECURE=1</option> will be set when invoking the pager, and the pager shall
++      disable commands that open or create new files or start new subprocesses. When
++      <varname>$SYSTEMD_PAGERSECURE</varname> is not set at all, pagers which are not known to implement
++      secure mode will not be used. (Currently only
++      <citerefentry><refentrytitle>less</refentrytitle><manvolnum>1</manvolnum></citerefentry> implements
++      secure mode.)</para>
++
++      <para>Note: when commands are invoked with elevated privileges, for example under <citerefentry
++      project='man-pages'><refentrytitle>sudo</refentrytitle><manvolnum>8</manvolnum></citerefentry> or
++      <citerefentry
++      project='die-net'><refentrytitle>pkexec</refentrytitle><manvolnum>1</manvolnum></citerefentry>, care
++      must be taken to ensure that unintended interactive features are not enabled. "Secure" mode for the
++      pager may be enabled automatically as describe above. Setting <varname>SYSTEMD_PAGERSECURE=0</varname>
++      or not removing it from the inherited environment allows the user to invoke arbitrary commands. Note
++      that if the <varname>$SYSTEMD_PAGER</varname> or <varname>$PAGER</varname> variables are to be
++      honoured, <varname>$SYSTEMD_PAGERSECURE</varname> must be set too. It might be reasonable to completly
++      disable the pager using <option>--no-pager</option> instead.</para></listitem>
+     </varlistentry>
+ 
+   </variablelist>
+diff --git a/src/shared/pager.c b/src/shared/pager.c
+index 6f1d57a096..0f53cad429 100644
+--- a/src/shared/pager.c
++++ b/src/shared/pager.c
+@@ -10,6 +10,8 @@
+ #include <sys/prctl.h>
+ #include <unistd.h>
+ 
++#include "sd-login.h"
++
+ #include "copy.h"
+ #include "env-util.h"
+ #include "fd-util.h"
+@@ -165,25 +167,42 @@ int pager_open(PagerFlags flags) {
+                 }
+ 
+                 /* People might invoke us from sudo, don't needlessly allow less to be a way to shell out
+-                 * privileged stuff. */
+-                r = getenv_bool("SYSTEMD_LESSSECURE");
+-                if (r == 0) { /* Remove env var if off */
+-                        if (unsetenv("LESSSECURE") < 0) {
+-                                log_error_errno(errno, "Failed to uset environment variable LESSSECURE: %m");
+-                                _exit(EXIT_FAILURE);
+-                        }
+-                } else {
+-                        /* Set env var otherwise */
++                 * privileged stuff. If the user set $SYSTEMD_PAGERSECURE, trust their configuration of the
++                 * pager. If they didn't, use secure mode when under euid is changed. If $SYSTEMD_PAGERSECURE
++                 * wasn't explicitly set, and we autodetect the need for secure mode, only use the pager we
++                 * know to be good. */
++                int use_secure_mode = getenv_bool("SYSTEMD_PAGERSECURE");
++                bool trust_pager = use_secure_mode >= 0;
++                if (use_secure_mode == -ENXIO) {
++                        uid_t uid;
++
++                        r = sd_pid_get_owner_uid(0, &uid);
+                         if (r < 0)
+-                                log_warning_errno(r, "Unable to parse $SYSTEMD_LESSSECURE, ignoring: %m");
++                                log_debug_errno(r, "sd_pid_get_owner_uid() failed, enabling pager secure mode: %m");
+ 
+-                        if (setenv("LESSSECURE", "1", 1) < 0) {
+-                                log_error_errno(errno, "Failed to set environment variable LESSSECURE: %m");
+-                                _exit(EXIT_FAILURE);
+-                        }
++                        use_secure_mode = r < 0 || uid != geteuid();
++
++                } else if (use_secure_mode < 0) {
++                        log_warning_errno(use_secure_mode, "Unable to parse $SYSTEMD_PAGERSECURE, assuming true: %m");
++                        use_secure_mode = true;
+                 }
+ 
+-                if (pager_args) {
++                /* We generally always set variables used by less, even if we end up using a different pager.
++                 * They shouldn't hurt in any case, and ideally other pagers would look at them too. */
++                if (use_secure_mode)
++                        r = setenv("LESSSECURE", "1", 1);
++                else
++                        r = unsetenv("LESSSECURE");
++                if (r < 0) {
++                        log_error_errno(errno, "Failed to adjust environment variable LESSSECURE: %m");
++                        _exit(EXIT_FAILURE);
++                }
++
++                if (trust_pager && pager_args) { /* The pager config might be set globally, and we cannot
++                                                  * know if the user adjusted it to be appropriate for the
++                                                  * secure mode. Thus, start the pager specified through
++                                                  * envvars only when $SYSTEMD_PAGERSECURE was explicitly set
++                                                  * as well. */
+                         r = loop_write(exe_name_pipe[1], pager_args[0], strlen(pager_args[0]) + 1, false);
+                         if (r < 0) {
+                                 log_error_errno(r, "Failed to write pager name to socket: %m");
+@@ -195,13 +214,14 @@ int pager_open(PagerFlags flags) {
+                                        "Failed to execute '%s', using fallback pagers: %m", pager_args[0]);
+                 }
+ 
+-                /* Debian's alternatives command for pagers is
+-                 * called 'pager'. Note that we do not call
+-                 * sensible-pagers here, since that is just a
+-                 * shell script that implements a logic that
+-                 * is similar to this one anyway, but is
+-                 * Debian-specific. */
++                /* Debian's alternatives command for pagers is called 'pager'. Note that we do not call
++                 * sensible-pagers here, since that is just a shell script that implements a logic that is
++                 * similar to this one anyway, but is Debian-specific. */
+                 FOREACH_STRING(exe, "pager", "less", "more") {
++                        /* Only less implements secure mode right now. */
++                        if (use_secure_mode && !streq(exe, "less"))
++                                continue;
++
+                         r = loop_write(exe_name_pipe[1], exe, strlen(exe) + 1, false);
+                         if (r  < 0) {
+                                 log_error_errno(r, "Failed to write pager name to socket: %m");
+@@ -212,6 +232,7 @@ int pager_open(PagerFlags flags) {
+                                        "Failed to execute '%s', using next fallback pager: %m", exe);
+                 }
+ 
++                /* Our builtin is also very secure. */
+                 r = loop_write(exe_name_pipe[1], "(built-in)", strlen("(built-in)") + 1, false);
+                 if (r < 0) {
+                         log_error_errno(r, "Failed to write pager name to socket: %m");
+-- 
+2.30.2
+