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systemd/0001-socket-introduce-SELinuxContextFromNet-option.patch

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Based on 16115b0a7b7cdf08fb38084d857d572d8a9088dc Mon Sep 17 00:00:00 2001
From: Michal Sekletar <msekleta@redhat.com>
Date: Thu, 24 Jul 2014 10:40:28 +0200
Subject: [PATCH] socket: introduce SELinuxContextFromNet option
This makes possible to spawn service instances triggered by socket with
MLS/MCS SELinux labels which are created based on information provided by
connected peer.
Implementation of label_get_child_mls_label derived from xinetd.
Reviewed-by: Paul Moore <pmoore@redhat.com>
---
man/systemd.socket.xml | 26 +++++++
src/core/execute.c | 30 +++++++--
src/core/execute.h | 1
src/core/load-fragment-gperf.gperf.m4 | 3
src/core/mount.c | 1
src/core/service.c | 4 -
src/core/service.h | 3
src/core/socket.c | 16 +++-
src/core/socket.h | 2
src/core/swap.c | 1
src/shared/label.c | 113 ++++++++++++++++++++++++++++++++++
src/shared/label.h | 2
12 files changed, 191 insertions(+), 11 deletions(-)
--- man/systemd.socket.xml
+++ man/systemd.socket.xml 2014-09-23 15:36:49.000000000 +0000
@@ -570,6 +570,32 @@
</varlistentry>
<varlistentry>
+ <term><varname>SELinuxContextFromNet=</varname></term>
+ <listitem><para>Takes a boolean
+ argument. When true systemd will attempt
+ to figure out the SELinux label used
+ for the instantiated service from the
+ information handed by the peer over the
+ network. Note that only the security
+ level is used from the information
+ provided by the peer. Other parts of
+ the resulting SELinux context originate
+ from either the target binary that is
+ effectively triggered by socket unit
+ are taken from the value of the
+ <varname>SELinuxContext=</varname>
+ option.This configuration option only
+ affects sockets with
+ <varname>Accept=</varname> mode set to
+ <literal>true</literal>. Also note that
+ this option is useful only when
+ MLS/MCS SELinux policy is
+ deployed. Defaults to
+ <literal>false</literal>.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
<term><varname>PipeSize=</varname></term>
<listitem><para>Takes an size in
bytes. Controls the pipe buffer size
--- src/core/execute.c
+++ src/core/execute.c 2014-09-24 09:22:08.882735864 +0000
@@ -82,6 +82,7 @@
#include "selinux-util.h"
#include "errno-list.h"
#include "apparmor-util.h"
+#include "label.h"
#ifdef HAVE_SECCOMP
#include "seccomp-util.h"
@@ -1123,6 +1124,7 @@ int exec_spawn(ExecCommand *command,
bool apply_chroot,
bool apply_tty_stdin,
bool confirm_spawn,
+ bool selinux_context_net,
CGroupControllerMask cgroup_supported,
const char *cgroup_path,
const char *unit_id,
@@ -1594,11 +1596,29 @@ int exec_spawn(ExecCommand *command,
#endif
#ifdef HAVE_SELINUX
- if (context->selinux_context && use_selinux()) {
- err = setexeccon(context->selinux_context);
- if (err < 0 && !context->selinux_context_ignore) {
- r = EXIT_SELINUX_CONTEXT;
- goto fail_child;
+ if (use_selinux()) {
+ if (context->selinux_context) {
+ err = setexeccon(context->selinux_context);
+ if (err < 0 && !context->selinux_context_ignore) {
+ r = EXIT_SELINUX_CONTEXT;
+ goto fail_child;
+ }
+ }
+
+ if (selinux_context_net && socket_fd >= 0) {
+ _cleanup_free_ char *label = NULL;
+
+ err = label_get_child_mls_label(socket_fd, command->path, &label);
+ if (err < 0) {
+ r = EXIT_SELINUX_CONTEXT;
+ goto fail_child;
+ }
+
+ err = setexeccon(label);
+ if (err < 0) {
+ r = EXIT_SELINUX_CONTEXT;
+ goto fail_child;
+ }
}
}
#endif
--- src/core/execute.h
+++ src/core/execute.h 2014-09-23 15:46:26.000000000 +0000
@@ -195,6 +195,7 @@ int exec_spawn(ExecCommand *command,
bool apply_chroot,
bool apply_tty_stdin,
bool confirm_spawn,
+ bool selinux_context_net,
CGroupControllerMask cgroup_mask,
const char *cgroup_path,
const char *unit_id,
--- src/core/load-fragment-gperf.gperf.m4
+++ src/core/load-fragment-gperf.gperf.m4 2014-09-23 00:00:00.000000000 +0000
@@ -242,6 +242,9 @@ Socket.SmackLabelIPOut, config_
`Socket.SmackLabel, config_parse_warn_compat, 0, 0
Socket.SmackLabelIPIn, config_parse_warn_compat, 0, 0
Socket.SmackLabelIPOut, config_parse_warn_compat, 0, 0')
+m4_ifdef(`HAVE_SELINUX',
+`Socket.SELinuxContextFromNet, config_parse_bool, 0, offsetof(Socket, selinux_context_from_net)',
+`Socket.SELinuxContextFromNet, config_parse_warn_compat, 0, 0')
EXEC_CONTEXT_CONFIG_ITEMS(Socket)m4_dnl
CGROUP_CONTEXT_CONFIG_ITEMS(Socket)m4_dnl
KILL_CONTEXT_CONFIG_ITEMS(Socket)m4_dnl
--- src/core/mount.c
+++ src/core/mount.c 2014-09-24 09:16:26.234235379 +0000
@@ -785,6 +785,7 @@ static int mount_spawn(Mount *m, ExecCom
true,
true,
UNIT(m)->manager->confirm_spawn,
+ false,
UNIT(m)->manager->cgroup_supported,
UNIT(m)->cgroup_path,
UNIT(m)->id,
--- src/core/service.c
+++ src/core/service.c 2014-09-23 15:49:24.000000000 +0000
@@ -1856,6 +1856,7 @@ static int service_spawn(
apply_chroot,
apply_tty_stdin,
UNIT(s)->manager->confirm_spawn,
+ s->socket_fd_selinux_context_net,
UNIT(s)->manager->cgroup_supported,
path,
UNIT(s)->id,
@@ -3787,7 +3788,7 @@ static void service_bus_name_owner_chang
}
}
-int service_set_socket_fd(Service *s, int fd, Socket *sock) {
+int service_set_socket_fd(Service *s, int fd, Socket *sock, bool selinux_context_net) {
_cleanup_free_ char *peer = NULL;
int r;
@@ -3825,6 +3826,7 @@ int service_set_socket_fd(Service *s, in
}
s->socket_fd = fd;
+ s->socket_fd_selinux_context_net = selinux_context_net;
unit_ref_set(&s->accept_socket, UNIT(sock));
--- src/core/service.h
+++ src/core/service.h 2014-09-23 15:51:13.000000000 +0000
@@ -159,6 +159,7 @@ struct Service {
pid_t main_pid, control_pid;
int socket_fd;
+ bool socket_fd_selinux_context_net;
bool permissions_start_only;
bool root_directory_start_only;
bool remain_after_exit;
@@ -204,7 +205,7 @@ extern const UnitVTable service_vtable;
struct Socket;
-int service_set_socket_fd(Service *s, int fd, struct Socket *socket);
+int service_set_socket_fd(Service *s, int fd, struct Socket *socket, bool selinux_context_net);
const char* service_state_to_string(ServiceState i) _const_;
ServiceState service_state_from_string(const char *s) _pure_;
--- src/core/socket.c
+++ src/core/socket.c 2014-09-24 09:13:29.698735735 +0000
@@ -453,7 +453,8 @@ static void socket_dump(Unit *u, FILE *f
"%sBroadcast: %s\n"
"%sPassCredentials: %s\n"
"%sPassSecurity: %s\n"
- "%sTCPCongestion: %s\n",
+ "%sTCPCongestion: %s\n"
+ "%sSELinuxContextFromNet: %s\n",
prefix, socket_state_to_string(s->state),
prefix, socket_result_to_string(s->result),
prefix, socket_address_bind_ipv6_only_to_string(s->bind_ipv6_only),
@@ -466,7 +467,8 @@ static void socket_dump(Unit *u, FILE *f
prefix, yes_no(s->broadcast),
prefix, yes_no(s->pass_cred),
prefix, yes_no(s->pass_sec),
- prefix, strna(s->tcp_congestion));
+ prefix, strna(s->tcp_congestion),
+ prefix, yes_no(s->selinux_context_from_net));
if (s->control_pid > 0)
fprintf(f,
@@ -1000,7 +1002,12 @@ static int socket_open_fds(Socket *s) {
if (p->type == SOCKET_SOCKET) {
- if (!know_label) {
+ if (!know_label && s->selinux_context_from_net) {
+ r = label_get_our_label(&label);
+ if (r < 0)
+ return r;
+ know_label = true;
+ } else if (!know_label) {
if ((r = socket_instantiate_service(s)) < 0)
return r;
@@ -1247,6 +1254,7 @@ static int socket_spawn(Socket *s, ExecC
true,
true,
UNIT(s)->manager->confirm_spawn,
+ s->selinux_context_from_net,
UNIT(s)->manager->cgroup_supported,
UNIT(s)->cgroup_path,
UNIT(s)->id,
@@ -1568,7 +1576,7 @@ static void socket_enter_running(Socket
unit_choose_id(UNIT(service), name);
- r = service_set_socket_fd(service, cfd, s);
+ r = service_set_socket_fd(service, cfd, s, s->selinux_context_from_net);
if (r < 0)
goto fail;
--- src/core/socket.h
+++ src/core/socket.h 2014-09-23 15:55:17.000000000 +0000
@@ -154,6 +154,8 @@ struct Socket {
char *smack;
char *smack_ip_in;
char *smack_ip_out;
+
+ bool selinux_context_from_net;
};
/* Called from the service code when collecting fds */
--- src/core/swap.c
+++ src/core/swap.c 2014-09-24 09:17:18.438735618 +0000
@@ -642,6 +642,7 @@ static int swap_spawn(Swap *s, ExecComma
true,
true,
UNIT(s)->manager->confirm_spawn,
+ false,
UNIT(s)->manager->cgroup_supported,
UNIT(s)->cgroup_path,
UNIT(s)->id,
--- src/shared/label.c
+++ src/shared/label.c 2014-09-23 00:00:00.000000000 +0000
@@ -31,6 +31,7 @@
#ifdef HAVE_SELINUX
#include <selinux/selinux.h>
#include <selinux/label.h>
+#include <selinux/context.h>
#endif
#include "label.h"
@@ -41,6 +42,12 @@
#include "smack-util.h"
#ifdef HAVE_SELINUX
+DEFINE_TRIVIAL_CLEANUP_FUNC(security_context_t, freecon);
+DEFINE_TRIVIAL_CLEANUP_FUNC(context_t, context_free);
+
+#define _cleanup_security_context_free_ _cleanup_(freeconp)
+#define _cleanup_context_free_ _cleanup_(context_freep)
+
static struct selabel_handle *label_hnd = NULL;
#endif
@@ -243,6 +250,112 @@ fail:
return r;
}
+int label_get_our_label(char **label) {
+ int r = -EOPNOTSUPP;
+ char *l = NULL;
+
+#ifdef HAVE_SELINUX
+ r = getcon(&l);
+ if (r < 0)
+ return r;
+
+ *label = l;
+#endif
+
+ return r;
+}
+
+int label_get_child_mls_label(int socket_fd, const char *exe, char **label) {
+ int r = -EOPNOTSUPP;
+
+#ifdef HAVE_SELINUX
+
+ _cleanup_security_context_free_ security_context_t mycon = NULL, peercon = NULL, fcon = NULL, ret = NULL;
+ _cleanup_context_free_ context_t pcon = NULL, bcon = NULL;
+ security_class_t sclass;
+
+ const char *range = NULL;
+
+ assert(socket_fd >= 0);
+ assert(exe);
+ assert(label);
+
+ r = getcon(&mycon);
+ if (r < 0) {
+ r = -EINVAL;
+ goto out;
+ }
+
+ r = getpeercon(socket_fd, &peercon);
+ if (r < 0) {
+ r = -EINVAL;
+ goto out;
+ }
+
+ r = getexeccon(&fcon);
+ if (r < 0) {
+ r = -EINVAL;
+ goto out;
+ }
+
+ if (!fcon) {
+ /* If there is no context set for next exec let's use context
+ of target executable */
+ r = getfilecon(exe, &fcon);
+ if (r < 0) {
+ r = -errno;
+ goto out;
+ }
+ }
+
+ bcon = context_new(mycon);
+ if (!bcon) {
+ r = -ENOMEM;
+ goto out;
+ }
+
+ pcon = context_new(peercon);
+ if (!pcon) {
+ r = -ENOMEM;
+ goto out;
+ }
+
+ range = context_range_get(pcon);
+ if (!range) {
+ r = -errno;
+ goto out;
+ }
+
+ r = context_range_set(bcon, range);
+ if (r) {
+ r = -errno;
+ goto out;
+ }
+
+ freecon(mycon);
+ mycon = context_str(bcon);
+ if (!mycon) {
+ r = -errno;
+ goto out;
+ }
+
+ sclass = string_to_security_class("process");
+ r = security_compute_create(mycon, fcon, sclass, &ret);
+ if (r < 0) {
+ r = -EINVAL;
+ goto out;
+ }
+
+ *label = ret;
+ r = 0;
+
+out:
+ if (r < 0 && security_getenforce() == 1)
+ return r;
+#endif
+ return r;
+}
+
int label_context_set(const char *path, mode_t mode) {
int r = 0;
--- src/shared/label.h
+++ src/shared/label.h 2014-09-23 00:00:00.000000000 +0000
@@ -40,6 +40,8 @@ void label_context_clear(void);
void label_free(const char *label);
int label_get_create_label_from_exe(const char *exe, char **label);
+int label_get_our_label(char **label);
+int label_get_child_mls_label(int socket_fd, const char *exec, char **label);
int label_mkdir(const char *path, mode_t mode);
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