ryantimwilson / rpms / systemd

Forked from rpms/systemd a month ago
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From af20a66874296f71618819ebce9d4335b195728c Mon Sep 17 00:00:00 2001
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From: Lennart Poettering <lennart@poettering.net>
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Date: Wed, 22 Jan 2020 12:04:38 +0100
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Subject: [PATCH] logind: check PolicyKit before allowing VT switch
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Let's lock this down a bit. Effectively nothing much changes, since the
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default PK policy will allow users on the VT to change VT. Only users
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with no local VT session won't be able to switch VTs.
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(cherry picked from commit 4acf0cfd2f92edb94ad48d04f1ce6c9ab4e19d55)
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Resolves: #1797679
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---
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 src/login/logind-dbus.c                 | 16 +++++++
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 src/login/logind-seat-dbus.c            | 58 ++++++++++++++++++++++++-
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 src/login/logind-session-dbus.c         | 15 +++++++
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 src/login/org.freedesktop.login1.policy | 10 +++++
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 4 files changed, 98 insertions(+), 1 deletion(-)
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diff --git a/src/login/logind-dbus.c b/src/login/logind-dbus.c
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index dca7f4a30f..3f122fcbd9 100644
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--- a/src/login/logind-dbus.c
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+++ b/src/login/logind-dbus.c
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@@ -913,6 +913,8 @@ static int method_activate_session(sd_bus_message *message, void *userdata, sd_b
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         if (r < 0)
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                 return r;
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+        /* PolicyKit is done by bus_session_method_activate() */
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+
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         return bus_session_method_activate(message, session, error);
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 }
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@@ -944,6 +946,20 @@ static int method_activate_session_on_seat(sd_bus_message *message, void *userda
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         if (session->seat != seat)
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                 return sd_bus_error_setf(error, BUS_ERROR_SESSION_NOT_ON_SEAT, "Session %s not on seat %s", session_name, seat_name);
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+        r = bus_verify_polkit_async(
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+                        message,
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+                        CAP_SYS_ADMIN,
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+                        "org.freedesktop.login1.chvt",
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+                        NULL,
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+                        false,
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+                        UID_INVALID,
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+                        &m->polkit_registry,
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+                        error);
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+        if (r < 0)
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+                return r;
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+        if (r == 0)
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+                return 1; /* Will call us back */
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+
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         r = session_activate(session);
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         if (r < 0)
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                 return r;
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diff --git a/src/login/logind-seat-dbus.c b/src/login/logind-seat-dbus.c
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index c4d9b067c6..2e590a8f21 100644
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--- a/src/login/logind-seat-dbus.c
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+++ b/src/login/logind-seat-dbus.c
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@@ -174,6 +174,20 @@ static int method_activate_session(sd_bus_message *message, void *userdata, sd_b
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         if (session->seat != s)
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                 return sd_bus_error_setf(error, BUS_ERROR_SESSION_NOT_ON_SEAT, "Session %s not on seat %s", name, s->id);
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+        r = bus_verify_polkit_async(
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+                        message,
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+                        CAP_SYS_ADMIN,
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+                        "org.freedesktop.login1.chvt",
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+                        NULL,
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+                        false,
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+                        UID_INVALID,
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+                        &s->manager->polkit_registry,
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+                        error);
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+        if (r < 0)
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+                return r;
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+        if (r == 0)
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+                return 1; /* Will call us back */
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+
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         r = session_activate(session);
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         if (r < 0)
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                 return r;
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@@ -194,7 +208,21 @@ static int method_switch_to(sd_bus_message *message, void *userdata, sd_bus_erro
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                 return r;
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         if (to <= 0)
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-                return -EINVAL;
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+                return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid virtual terminal");
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+
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+        r = bus_verify_polkit_async(
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+                        message,
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+                        CAP_SYS_ADMIN,
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+                        "org.freedesktop.login1.chvt",
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+                        NULL,
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+                        false,
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+                        UID_INVALID,
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+                        &s->manager->polkit_registry,
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+                        error);
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+        if (r < 0)
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+                return r;
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+        if (r == 0)
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+                return 1; /* Will call us back */
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         r = seat_switch_to(s, to);
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         if (r < 0)
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@@ -210,6 +238,20 @@ static int method_switch_to_next(sd_bus_message *message, void *userdata, sd_bus
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         assert(message);
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         assert(s);
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+        r = bus_verify_polkit_async(
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+                        message,
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+                        CAP_SYS_ADMIN,
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+                        "org.freedesktop.login1.chvt",
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+                        NULL,
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+                        false,
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+                        UID_INVALID,
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+                        &s->manager->polkit_registry,
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+                        error);
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+        if (r < 0)
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+                return r;
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+        if (r == 0)
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+                return 1; /* Will call us back */
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+
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         r = seat_switch_to_next(s);
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         if (r < 0)
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                 return r;
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@@ -224,6 +266,20 @@ static int method_switch_to_previous(sd_bus_message *message, void *userdata, sd
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         assert(message);
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         assert(s);
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+        r = bus_verify_polkit_async(
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+                        message,
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+                        CAP_SYS_ADMIN,
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+                        "org.freedesktop.login1.chvt",
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+                        NULL,
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+                        false,
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+                        UID_INVALID,
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+                        &s->manager->polkit_registry,
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+                        error);
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+        if (r < 0)
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+                return r;
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+        if (r == 0)
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+                return 1; /* Will call us back */
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+
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         r = seat_switch_to_previous(s);
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         if (r < 0)
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                 return r;
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diff --git a/src/login/logind-session-dbus.c b/src/login/logind-session-dbus.c
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index 25c4981dc0..88a2d33dc8 100644
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--- a/src/login/logind-session-dbus.c
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+++ b/src/login/logind-session-dbus.c
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@@ -13,6 +13,7 @@
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 #include "logind.h"
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 #include "signal-util.h"
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 #include "strv.h"
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+#include "user-util.h"
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 #include "util.h"
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 static int property_get_user(
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@@ -182,6 +183,20 @@ int bus_session_method_activate(sd_bus_message *message, void *userdata, sd_bus_
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         assert(message);
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         assert(s);
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+        r = bus_verify_polkit_async(
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+                        message,
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+                        CAP_SYS_ADMIN,
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+                        "org.freedesktop.login1.chvt",
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+                        NULL,
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+                        false,
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+                        UID_INVALID,
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+                        &s->manager->polkit_registry,
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+                        error);
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+        if (r < 0)
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+                return r;
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+        if (r == 0)
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+                return 1; /* Will call us back */
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+
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         r = session_activate(s);
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         if (r < 0)
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                 return r;
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diff --git a/src/login/org.freedesktop.login1.policy b/src/login/org.freedesktop.login1.policy
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index f1d1f956d3..83760e1580 100644
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--- a/src/login/org.freedesktop.login1.policy
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+++ b/src/login/org.freedesktop.login1.policy
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@@ -357,4 +357,14 @@
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                 </defaults>
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         </action>
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+        <action id="org.freedesktop.login1.chvt">
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+                <description gettext-domain="systemd">Change Session</description>
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+                <message gettext-domain="systemd">Authentication is required for changing the virtual terminal.</message>
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+                <defaults>
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+                        <allow_any>auth_admin_keep</allow_any>
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+                        <allow_inactive>auth_admin_keep</allow_inactive>
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+                        <allow_active>yes</allow_active>
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+                </defaults>
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+        </action>
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+
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 </policyconfig>