socket: SELinux support for socket creation.

It seems to work on my machine.

/proc/1/fd/20	system_u:system_r:system_dbusd_t:s0

/proc/1/fd/21	system_u:system_r:avahi_t:s0

And the AVC's seem to have dissapeared when a confined app trys to
connect to dbus or avahi.

If you run with this patch and selinux-policy-3.8.8-3.fc14.noarch
You should be able to boot in enforcing mode.

1 files changed, 84 insertions, 18 deletions

diff --git a/src/socket.c b/src/socket.c
index b06ba093fb..82a9348d13 100644
--- a/src/socket.c
+++ b/src/socket.c
@@ -27,6 +27,7 @@
 #include <sys/epoll.h>
 #include <signal.h>
 #include <arpa/inet.h>
+#include <selinux/selinux.h>
 
 #include "unit.h"
 #include "socket.h"
@@ -642,24 +643,89 @@ static void socket_apply_fifo_options(Socket *s, int fd) {
                         log_warning("F_SETPIPE_SZ: %m");
 }
 
+static int selinux_getconfromexe(
+                const char *exe,
+                security_context_t *newcon) {
+
+        security_context_t mycon = NULL, fcon = NULL;
+        security_class_t sclass;
+        int r = 0;
+
+        r = getcon(&mycon);
+        if (r < 0)
+                goto fail;
+
+        r = getfilecon(exe, &fcon);
+        if (r < 0)
+                goto fail;
+
+        sclass = string_to_security_class("process");
+        r = security_compute_create(mycon, fcon, sclass, newcon);
+
+fail:
+        if (r < 0)
+                r = -errno;
+
+        freecon(mycon);
+        freecon(fcon);
+        return r;
+}
+
+static int selinux_getfileconfrompath(
+                const security_context_t scon,
+                const char *path,
+                const char *class,
+                security_context_t *fcon) {
+
+        security_context_t dir_con = NULL;
+        security_class_t sclass;
+        int r = 0;
+
+        r = getfilecon(path, &dir_con);
+        if (r >= 0) {
+                r = -1;
+                if ((sclass = string_to_security_class(class)) != 0)
+                        r = security_compute_create(scon, dir_con, sclass, fcon);
+        }
+        if (r < 0)
+                r = -errno;
+
+        freecon(dir_con);
+        return r;
+}
+
 static int fifo_address_create(
                 const char *path,
                 mode_t directory_mode,
                 mode_t socket_mode,
-                /* FIXME SELINUX: pass SELinux context object here */
+                security_context_t scon,
                 int *_fd) {
 
-        int fd = -1, r;
+        int fd = -1, r = 0;
         struct stat st;
         mode_t old_mask;
+        security_context_t filecon = NULL;
 
         assert(path);
         assert(_fd);
 
         mkdir_parents(path, directory_mode);
 
-        /* FIXME SELINUX: The mkfifo here should be done with
-         * the right SELinux context set */
+        if (scon) {
+                if (scon && ((r = selinux_getfileconfrompath(scon, path, "fifo_file", &filecon)) == 0)) {
+                        r = setfscreatecon(filecon);
+
+                        if (r < 0) {
+                                log_error("Failed to set SELinux file context (%s) on %s: %m", scon, path);
+                                r = -errno;
+                        }
+
+                        freecon(filecon);
+                }
+
+                if (r < 0  && security_getenforce() == 1)
+                        goto fail;
+        }
 
         /* Enforce the right access mode for the fifo */
         old_mask = umask(~ socket_mode);
@@ -680,6 +746,8 @@ static int fifo_address_create(
                 goto fail;
         }
 
+        setfscreatecon(NULL);
+
         if (fstat(fd, &st) < 0) {
                 r = -errno;
                 goto fail;
@@ -698,6 +766,7 @@ static int fifo_address_create(
         return 0;
 
 fail:
+        setfscreatecon(NULL);
         if (fd >= 0)
                 close_nointr_nofail(fd);
 
@@ -707,25 +776,20 @@ fail:
 static int socket_open_fds(Socket *s) {
         SocketPort *p;
         int r;
+        security_context_t scon = NULL;
 
         assert(s);
 
-        /* FIXME SELINUX: Somewhere here we must set the the SELinux
-           context for the created sockets and FIFOs. To figure out
-           the executable name for this, use
-           socket_instantiate_service() and then access the executable
-           path name via
-           s->service->exec_command[SERVICE_EXEC_START]->path. Example:
-
         if ((r = socket_instantiate_service(s)) < 0)
                 return r;
 
-        log_debug("Socket unit %s will spawn service unit %s with executable path %s.",
-                  s->meta.id,
-                  s->service->meta.id,
-                  s->service->exec_command[SERVICE_EXEC_START]->path);
-        */
+        if (selinux_getconfromexe(s->service->exec_command[SERVICE_EXEC_START]->path, &scon) < 0) {
+                log_error("Failed to get SELinux exec context for %s \n", s->service->exec_command[SERVICE_EXEC_START]->path);
+                if (security_getenforce() == 1)
+                        return -errno;
+        }
 
+        log_debug("SELinux Socket context for %s set to %s\n", s->service->exec_command[SERVICE_EXEC_START]->path, scon);
         LIST_FOREACH(port, p, s->ports) {
 
                 if (p->fd >= 0)
@@ -741,7 +805,7 @@ static int socket_open_fds(Socket *s) {
                                              s->free_bind,
                                              s->directory_mode,
                                              s->socket_mode,
-                                             /* FIXME SELINUX: Pass the SELinux context object here */
+                                             scon,
                                              &p->fd)) < 0)
                                 goto rollback;
 
@@ -753,7 +817,7 @@ static int socket_open_fds(Socket *s) {
                                              p->path,
                                              s->directory_mode,
                                              s->socket_mode,
-                                             /* FIXME SELINUX: Pass the SELinux context object here */
+                                             scon,
                                              &p->fd)) < 0)
                                 goto rollback;
 
@@ -763,10 +827,12 @@ static int socket_open_fds(Socket *s) {
                         assert_not_reached("Unknown port type");
         }
 
+        freecon(scon);
         return 0;
 
 rollback:
         socket_close_fds(s);
+        freecon(scon);
         return r;
 }