398 lines
14 KiB
Diff
398 lines
14 KiB
Diff
From 16115b0a7b7cdf08fb38084d857d572d8a9088dc Mon Sep 17 00:00:00 2001
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From: Michal Sekletar <msekleta@redhat.com>
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Date: Thu, 24 Jul 2014 10:40:28 +0200
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Subject: [PATCH] socket: introduce SELinuxContextFromNet option
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This makes possible to spawn service instances triggered by socket with
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MLS/MCS SELinux labels which are created based on information provided by
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connected peer.
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Implementation of label_get_child_mls_label derived from xinetd.
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Reviewed-by: Paul Moore <pmoore@redhat.com>
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---
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man/systemd.socket.xml | 26 ++++++++
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src/core/execute.c | 29 +++++++--
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src/core/execute.h | 1 +
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src/core/load-fragment-gperf.gperf.m4 | 3 +
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src/core/service.c | 4 +-
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src/core/service.h | 3 +-
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src/core/socket.c | 16 +++--
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src/core/socket.h | 2 +
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src/shared/label.c | 113 ++++++++++++++++++++++++++++++++++
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src/shared/label.h | 2 +
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10 files changed, 187 insertions(+), 12 deletions(-)
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diff --git a/man/systemd.socket.xml b/man/systemd.socket.xml
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index 7a63348caf..dad0267467 100644
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--- a/man/systemd.socket.xml
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+++ b/man/systemd.socket.xml
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@@ -676,6 +676,32 @@
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</varlistentry>
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<varlistentry>
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+ <term><varname>SELinuxContextFromNet=</varname></term>
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+ <listitem><para>Takes a boolean
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+ argument. When true systemd will attempt
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+ to figure out the SELinux label used
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+ for the instantiated service from the
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+ information handed by the peer over the
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+ network. Note that only the security
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+ level is used from the information
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+ provided by the peer. Other parts of
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+ the resulting SELinux context originate
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+ from either the target binary that is
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+ effectively triggered by socket unit
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+ are taken from the value of the
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+ <varname>SELinuxContext=</varname>
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+ option.This configuration option only
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+ affects sockets with
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+ <varname>Accept=</varname> mode set to
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+ <literal>true</literal>. Also note that
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+ this option is useful only when
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+ MLS/MCS SELinux policy is
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+ deployed. Defaults to
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+ <literal>false</literal>.
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+ </para></listitem>
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+ </varlistentry>
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+
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+ <varlistentry>
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<term><varname>PipeSize=</varname></term>
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<listitem><para>Takes a size in
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bytes. Controls the pipe buffer size
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diff --git a/src/core/execute.c b/src/core/execute.c
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index db755777c1..8c9dfde00a 100644
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--- a/src/core/execute.c
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+++ b/src/core/execute.c
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@@ -84,6 +84,7 @@
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#include "mkdir.h"
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#include "apparmor-util.h"
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#include "bus-kernel.h"
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+#include "label.h"
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#ifdef HAVE_SECCOMP
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#include "seccomp-util.h"
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@@ -1665,11 +1666,29 @@ static int exec_child(ExecCommand *command,
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#endif
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#ifdef HAVE_SELINUX
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- if (context->selinux_context && use_selinux()) {
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- err = setexeccon(context->selinux_context);
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- if (err < 0 && !context->selinux_context_ignore) {
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- *error = EXIT_SELINUX_CONTEXT;
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- return err;
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+ if (use_selinux()) {
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+ if (context->selinux_context) {
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+ err = setexeccon(context->selinux_context);
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+ if (err < 0 && !context->selinux_context_ignore) {
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+ *error = EXIT_SELINUX_CONTEXT;
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+ return err;
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+ }
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+ }
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+
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+ if (params->selinux_context_net && socket_fd >= 0) {
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+ _cleanup_free_ char *label = NULL;
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+
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+ err = label_get_child_mls_label(socket_fd, command->path, &label);
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+ if (err < 0) {
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+ *error = EXIT_SELINUX_CONTEXT;
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+ return err;
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+ }
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+
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+ err = setexeccon(label);
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+ if (err < 0) {
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+ *error = EXIT_SELINUX_CONTEXT;
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+ return err;
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+ }
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}
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}
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#endif
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diff --git a/src/core/execute.h b/src/core/execute.h
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index 9c1f249cd4..6f35736eda 100644
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--- a/src/core/execute.h
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+++ b/src/core/execute.h
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@@ -204,6 +204,7 @@ struct ExecParameters {
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bool apply_chroot;
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bool apply_tty_stdin;
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bool confirm_spawn;
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+ bool selinux_context_net;
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CGroupControllerMask cgroup_supported;
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const char *cgroup_path;
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const char *runtime_prefix;
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diff --git a/src/core/load-fragment-gperf.gperf.m4 b/src/core/load-fragment-gperf.gperf.m4
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index e764d68ce4..050c5d819f 100644
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--- a/src/core/load-fragment-gperf.gperf.m4
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+++ b/src/core/load-fragment-gperf.gperf.m4
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@@ -265,6 +265,9 @@ Socket.SmackLabelIPOut, config_parse_string, 0,
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`Socket.SmackLabel, config_parse_warn_compat, 0, 0
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Socket.SmackLabelIPIn, config_parse_warn_compat, 0, 0
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Socket.SmackLabelIPOut, config_parse_warn_compat, 0, 0')
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+m4_ifdef(`HAVE_SELINUX',
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+`Socket.SELinuxContextFromNet, config_parse_bool, 0, offsetof(Socket, selinux_context_from_net)',
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+`Socket.SELinuxContextFromNet, config_parse_warn_compat, 0, 0')
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EXEC_CONTEXT_CONFIG_ITEMS(Socket)m4_dnl
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CGROUP_CONTEXT_CONFIG_ITEMS(Socket)m4_dnl
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KILL_CONTEXT_CONFIG_ITEMS(Socket)m4_dnl
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diff --git a/src/core/service.c b/src/core/service.c
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index 3f6595c5c8..395e0ca8c6 100644
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--- a/src/core/service.c
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+++ b/src/core/service.c
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@@ -901,6 +901,7 @@ static int service_spawn(
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.apply_chroot = apply_chroot,
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.apply_tty_stdin = apply_tty_stdin,
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.bus_endpoint_fd = -1,
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+ .selinux_context_net = s->socket_fd_selinux_context_net
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};
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assert(s);
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@@ -2748,7 +2749,7 @@ static void service_bus_name_owner_change(
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}
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}
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-int service_set_socket_fd(Service *s, int fd, Socket *sock) {
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+int service_set_socket_fd(Service *s, int fd, Socket *sock, bool selinux_context_net) {
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_cleanup_free_ char *peer = NULL;
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int r;
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@@ -2786,6 +2787,7 @@ int service_set_socket_fd(Service *s, int fd, Socket *sock) {
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}
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s->socket_fd = fd;
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+ s->socket_fd_selinux_context_net = selinux_context_net;
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unit_ref_set(&s->accept_socket, UNIT(sock));
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diff --git a/src/core/service.h b/src/core/service.h
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index ad0b3b381e..0db0c4d64c 100644
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--- a/src/core/service.h
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+++ b/src/core/service.h
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@@ -161,6 +161,7 @@ struct Service {
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pid_t main_pid, control_pid;
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int socket_fd;
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+ bool socket_fd_selinux_context_net;
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int bus_endpoint_fd;
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@@ -205,7 +206,7 @@ extern const UnitVTable service_vtable;
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struct Socket;
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-int service_set_socket_fd(Service *s, int fd, struct Socket *socket);
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+int service_set_socket_fd(Service *s, int fd, struct Socket *socket, bool selinux_context_net);
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const char* service_state_to_string(ServiceState i) _const_;
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ServiceState service_state_from_string(const char *s) _pure_;
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diff --git a/src/core/socket.c b/src/core/socket.c
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index 68e21e60ac..00d5fd1192 100644
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--- a/src/core/socket.c
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+++ b/src/core/socket.c
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@@ -489,7 +489,8 @@ static void socket_dump(Unit *u, FILE *f, const char *prefix) {
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"%sPassCredentials: %s\n"
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"%sPassSecurity: %s\n"
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"%sTCPCongestion: %s\n"
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- "%sRemoveOnStop: %s\n",
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+ "%sRemoveOnStop: %s\n"
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+ "%sSELinuxContextFromNet: %s\n",
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prefix, socket_state_to_string(s->state),
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prefix, socket_result_to_string(s->result),
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prefix, socket_address_bind_ipv6_only_to_string(s->bind_ipv6_only),
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@@ -504,7 +505,8 @@ static void socket_dump(Unit *u, FILE *f, const char *prefix) {
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prefix, yes_no(s->pass_cred),
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prefix, yes_no(s->pass_sec),
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prefix, strna(s->tcp_congestion),
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- prefix, yes_no(s->remove_on_stop));
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+ prefix, yes_no(s->remove_on_stop),
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+ prefix, yes_no(s->selinux_context_from_net));
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if (s->control_pid > 0)
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fprintf(f,
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@@ -1128,8 +1130,12 @@ static int socket_open_fds(Socket *s) {
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continue;
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if (p->type == SOCKET_SOCKET) {
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-
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- if (!know_label) {
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+ if (!know_label && s->selinux_context_from_net) {
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+ r = label_get_our_label(&label);
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+ if (r < 0)
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+ return r;
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+ know_label = true;
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+ } else if (!know_label) {
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r = socket_instantiate_service(s);
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if (r < 0)
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@@ -1821,7 +1827,7 @@ static void socket_enter_running(Socket *s, int cfd) {
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unit_choose_id(UNIT(service), name);
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- r = service_set_socket_fd(service, cfd, s);
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+ r = service_set_socket_fd(service, cfd, s, s->selinux_context_from_net);
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if (r < 0)
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goto fail;
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diff --git a/src/core/socket.h b/src/core/socket.h
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index eede70564a..a2e08998c0 100644
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--- a/src/core/socket.h
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+++ b/src/core/socket.h
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@@ -165,6 +165,8 @@ struct Socket {
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char *smack_ip_in;
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char *smack_ip_out;
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+ bool selinux_context_from_net;
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+
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char *user, *group;
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};
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diff --git a/src/shared/label.c b/src/shared/label.c
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index 25a8b361b7..02b41f02d8 100644
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--- a/src/shared/label.c
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+++ b/src/shared/label.c
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@@ -31,6 +31,7 @@
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#ifdef HAVE_SELINUX
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#include <selinux/selinux.h>
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#include <selinux/label.h>
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+#include <selinux/context.h>
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#endif
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#include "label.h"
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@@ -41,6 +42,12 @@
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#include "smack-util.h"
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#ifdef HAVE_SELINUX
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+DEFINE_TRIVIAL_CLEANUP_FUNC(security_context_t, freecon);
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+DEFINE_TRIVIAL_CLEANUP_FUNC(context_t, context_free);
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+
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+#define _cleanup_security_context_free_ _cleanup_(freeconp)
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+#define _cleanup_context_free_ _cleanup_(context_freep)
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+
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static struct selabel_handle *label_hnd = NULL;
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#endif
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@@ -243,6 +250,112 @@ fail:
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return r;
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}
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+int label_get_our_label(char **label) {
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+ int r = -EOPNOTSUPP;
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+ char *l = NULL;
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+
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+#ifdef HAVE_SELINUX
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+ r = getcon(&l);
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+ if (r < 0)
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+ return r;
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+
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+ *label = l;
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+#endif
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+
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+ return r;
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+}
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+
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+int label_get_child_mls_label(int socket_fd, const char *exe, char **label) {
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+ int r = -EOPNOTSUPP;
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+
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+#ifdef HAVE_SELINUX
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+
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+ _cleanup_security_context_free_ security_context_t mycon = NULL, peercon = NULL, fcon = NULL, ret = NULL;
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+ _cleanup_context_free_ context_t pcon = NULL, bcon = NULL;
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+ security_class_t sclass;
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+
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+ const char *range = NULL;
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+
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+ assert(socket_fd >= 0);
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+ assert(exe);
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+ assert(label);
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+
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+ r = getcon(&mycon);
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+ if (r < 0) {
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+ r = -EINVAL;
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+ goto out;
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+ }
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+
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+ r = getpeercon(socket_fd, &peercon);
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+ if (r < 0) {
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+ r = -EINVAL;
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+ goto out;
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+ }
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+
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+ r = getexeccon(&fcon);
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+ if (r < 0) {
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+ r = -EINVAL;
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+ goto out;
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+ }
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+
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+ if (!fcon) {
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+ /* If there is no context set for next exec let's use context
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+ of target executable */
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+ r = getfilecon(exe, &fcon);
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+ if (r < 0) {
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+ r = -errno;
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+ goto out;
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+ }
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+ }
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+
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+ bcon = context_new(mycon);
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+ if (!bcon) {
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+ r = -ENOMEM;
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+ goto out;
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+ }
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+
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+ pcon = context_new(peercon);
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+ if (!pcon) {
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+ r = -ENOMEM;
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+ goto out;
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+ }
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+
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+ range = context_range_get(pcon);
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+ if (!range) {
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+ r = -errno;
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+ goto out;
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+ }
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+
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+ r = context_range_set(bcon, range);
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+ if (r) {
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+ r = -errno;
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+ goto out;
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+ }
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+
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+ freecon(mycon);
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+ mycon = context_str(bcon);
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+ if (!mycon) {
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+ r = -errno;
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+ goto out;
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+ }
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+
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+ sclass = string_to_security_class("process");
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+ r = security_compute_create(mycon, fcon, sclass, &ret);
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+ if (r < 0) {
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+ r = -EINVAL;
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+ goto out;
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+ }
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+
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+ *label = ret;
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+ r = 0;
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+
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+out:
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+ if (r < 0 && security_getenforce() == 1)
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+ return r;
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+#endif
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+ return r;
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+}
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+
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int label_context_set(const char *path, mode_t mode) {
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int r = 0;
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diff --git a/src/shared/label.h b/src/shared/label.h
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index cb2ec79eea..ce1e5c3f57 100644
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--- a/src/shared/label.h
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+++ b/src/shared/label.h
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@@ -40,6 +40,8 @@ void label_context_clear(void);
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void label_free(const char *label);
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int label_get_create_label_from_exe(const char *exe, char **label);
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+int label_get_our_label(char **label);
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+int label_get_child_mls_label(int socket_fd, const char *exec, char **label);
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int label_mkdir(const char *path, mode_t mode);
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