SMACK: Add configuration options. (v3)

This adds SMACK label configuration options to socket units.

SMACK labels should be applied to most objects on disk well before
execution time, but two items remain that are generated dynamically
at run time that require SMACK labels to be set in order to enforce
MAC on all objects.

Files on disk can be labelled using package management.

For device nodes, simple udev rules are sufficient to add SMACK labels
at boot/insertion time.

Sockets can be created at run time and systemd does just that for
several services. In order to protect FIFO's and UNIX domain sockets,
we must instruct systemd to apply SMACK labels at runtime.

This patch adds the following options:

Smack - applicable to FIFO's.
SmackIpIn/SmackIpOut - applicable to sockets.

No external dependencies are required to support SMACK, as setting
the labels is done using fsetxattr(). The labels can be set on a
kernel that does not have SMACK enabled either, so there is no need
to #ifdef any of this code out.

For more information about SMACK, please see Documentation/Smack.txt
in the kernel source code.

v3 of this patch changes the config options to be CamelCased.

diff --git a/man/systemd.socket.xml b/man/systemd.socket.xml
index 9db39b1de9d0921359d4d75860124d4ed97f2316..ae8497e8ab4c3a9b399f9f9999a44a9d56e0997c 100644 (file)
--- a/man/systemd.socket.xml
+++ b/man/systemd.socket.xml
@@ -484,6 +484,26 @@
                                 for details.</para></listitem>
                         </varlistentry>
 
+                        <varlistentry>
+                                <term><varname>SmackLabel=</varname></term>
+                                <term><varname>SmackLabelIPIn=</varname></term>
+                                <term><varname>SmackLabelIPOut=</varname></term>
+                                <listitem><para>Takes a string
+                                value. Controls the extended
+                                attributes
+                                <literal>security.SMACK64</literal>,
+                                <literal>security.SMACK64IPIN</literal>
+                                and
+                                <literal>security.SMACK64IPOUT</literal>,
+                                respectively, i.e. the security label
+                                of the FIFO, or the security label for
+                                the incoming or outgoing connections
+                                of the socket, respectively.  See
+                                <ulink
+                                url="https://www.kernel.org/doc/Documentation/security/Smack.txt">Smack.txt</ulink>
+                                for details.</para></listitem>
+                        </varlistentry>
+
                         <varlistentry>
                                 <term><varname>PipeSize=</varname></term>
                                 <listitem><para>Takes an integer

diff --git a/src/core/dbus-socket.c b/src/core/dbus-socket.c
index c57cce19fbdfbcb51ab53b6ca600e2b114ad001e..095a0316120c16a7d6fe8546dac5919ecee195bc 100644 (file)
--- a/src/core/dbus-socket.c
+++ b/src/core/dbus-socket.c
@@ -63,6 +63,9 @@
         "  <property name=\"MessageQueueMaxMessages\" type=\"x\" access=\"read\"/>\n" \
         "  <property name=\"MessageQueueMessageSize\" type=\"x\" access=\"read\"/>\n" \
         "  <property name=\"Result\" type=\"s\" access=\"read\"/>\n"    \
+        "  <property name=\"SmackLabel\" type=\"s\" access=\"read\"/>\n" \
+        "  <property name=\"SmackLabelIPIn\" type=\"s\" access=\"read\"/>\n" \
+        "  <property name=\"SmackLabelIPOut\" type=\"s\" access=\"read\"/>\n" \
         " </interface>\n"                                               \
 
 #define INTROSPECTION                                                   \
@@ -126,6 +129,9 @@ static const BusProperty bus_socket_properties[] = {
         { "MessageQueueMaxMessages", bus_property_append_long, "x", offsetof(Socket, mq_maxmsg)       },
         { "MessageQueueMessageSize", bus_property_append_long, "x", offsetof(Socket, mq_msgsize)      },
         { "Result",         bus_socket_append_socket_result,   "s", offsetof(Socket, result)          },
+        { "SmackLabel",     bus_property_append_string,        "s", offsetof(Socket, smack),          true },
+        { "SmackLabelIPIn", bus_property_append_string,        "s", offsetof(Socket, smack_ip_in),    true },
+        { "SmackLabelIPOut",bus_property_append_string,        "s", offsetof(Socket, smack_ip_out),   true },
         { NULL, }
 };
 

diff --git a/src/core/load-fragment-gperf.gperf.m4 b/src/core/load-fragment-gperf.gperf.m4
index 8187cd48c615b2c8f0971d58a07a964026794836..0c5ccebd736f4bc78e0db1b13845f45f4b398453 100644 (file)
--- a/src/core/load-fragment-gperf.gperf.m4
+++ b/src/core/load-fragment-gperf.gperf.m4
@@ -208,6 +208,9 @@ Socket.TCPCongestion,            config_parse_string,                0,
 Socket.MessageQueueMaxMessages,  config_parse_long,                  0,                             offsetof(Socket, mq_maxmsg)
 Socket.MessageQueueMessageSize,  config_parse_long,                  0,                             offsetof(Socket, mq_msgsize)
 Socket.Service,                  config_parse_socket_service,        0,                             0
+Socket.SmackLabel,               config_parse_string,                0,                             offsetof(Socket, smack)
+Socket.SmackLabelIPIn,           config_parse_string,                0,                             offsetof(Socket, smack_ip_in)
+Socket.SmackLabelIPOut,          config_parse_string,                0,                             offsetof(Socket, smack_ip_out)
 EXEC_CONTEXT_CONFIG_ITEMS(Socket)m4_dnl
 KILL_CONTEXT_CONFIG_ITEMS(Socket)m4_dnl
 m4_dnl

diff --git a/src/core/socket.c b/src/core/socket.c
index 71cdf2dfc83acb8821434602609d5349dc258128..c0959815c174c89d34cd56082286a4a4507a403d 100644 (file)
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -28,6 +28,7 @@
 #include <signal.h>
 #include <arpa/inet.h>
 #include <mqueue.h>
+#include <attr/xattr.h>
 
 #include "unit.h"
 #include "socket.h"
@@ -131,6 +132,10 @@ static void socket_done(Unit *u) {
         free(s->bind_to_device);
         s->bind_to_device = NULL;
 
+        free(s->smack);
+        free(s->smack_ip_in);
+        free(s->smack_ip_out);
+
         unit_unwatch_timer(u, &s->timer_watch);
 }
 
@@ -508,6 +513,21 @@ static void socket_dump(Unit *u, FILE *f, const char *prefix) {
                         "%sMessageQueueMessageSize: %li\n",
                         prefix, s->mq_msgsize);
 
+        if (s->smack)
+                fprintf(f,
+                        "%sSmackLabel: %s\n",
+                        prefix, s->smack);
+
+        if (s->smack_ip_in)
+                fprintf(f,
+                        "%sSmackLabelIPIn: %s\n",
+                        prefix, s->smack_ip_in);
+
+        if (s->smack_ip_out)
+                fprintf(f,
+                        "%sSmackLabelIPOut: %s\n",
+                        prefix, s->smack_ip_out);
+
         LIST_FOREACH(port, p, s->ports) {
 
                 if (p->type == SOCKET_SOCKET) {
@@ -747,6 +767,14 @@ static void socket_apply_socket_options(Socket *s, int fd) {
         if (s->tcp_congestion)
                 if (setsockopt(fd, SOL_TCP, TCP_CONGESTION, s->tcp_congestion, strlen(s->tcp_congestion)+1) < 0)
                         log_warning("TCP_CONGESTION failed: %m");
+
+        if (s->smack_ip_in)
+                if (fsetxattr(fd, "security.SMACK64IPIN", s->smack_ip_in, strlen(s->smack_ip_in), 0) < 0)
+                        log_error("fsetxattr(\"security.SMACK64IPIN\"): %m");
+
+        if (s->smack_ip_out)
+                if (fsetxattr(fd, "security.SMACK64IPOUT", s->smack_ip_out, strlen(s->smack_ip_out), 0) < 0)
+                        log_error("fsetxattr(\"security.SMACK64IPOUT\"): %m");
 }
 
 static void socket_apply_fifo_options(Socket *s, int fd) {
@@ -756,6 +784,10 @@ static void socket_apply_fifo_options(Socket *s, int fd) {
         if (s->pipe_size > 0)
                 if (fcntl(fd, F_SETPIPE_SZ, s->pipe_size) < 0)
                         log_warning("F_SETPIPE_SZ: %m");
+
+        if (s->smack)
+                if (fsetxattr(fd, "security.SMACK64", s->smack, strlen(s->smack), 0) < 0)
+                        log_error("fsetxattr(\"security.SMACK64\"): %m");
 }
 
 static int fifo_address_create(

diff --git a/src/core/socket.h b/src/core/socket.h
index a06b3eae9407567c746588707a149410387f6b1e..f099520dcef1015164dc9b4067c4d40752a0f4a7 100644 (file)
--- a/src/core/socket.h
+++ b/src/core/socket.h
@@ -144,6 +144,10 @@ struct Socket {
 
         /* Only for INET6 sockets: issue IPV6_V6ONLY sockopt */
         SocketAddressBindIPv6Only bind_ipv6_only;
+
+        char *smack;
+        char *smack_ip_in;
+        char *smack_ip_out;
 };
 
 /* Called from the service code when collecting fds */