Systemd is causing mislabeled devices to be created and then attempting to read them.

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Hash: SHA1

On 07/28/2010 05:57 AM, Kay Sievers wrote:
> On Wed, Jul 28, 2010 at 11:43, Lennart Poettering
> <lennart@poettering.net> wrote:
>> On Mon, 26.07.10 16:42, Daniel J Walsh (dwalsh@redhat.com) wrote:
>>> tcontext=system_u:object_r:device_t:s0 tclass=chr_file
>>> type=1400 audit(1280174589.476:7): avc:  denied  { read } for  pid=1
>>> comm="systemd" name="autofs" dev=devtmpfs ino=9482
>>> scontext=system_u:system_r:init_t:s0
>>> tcontext=system_u:object_r:device_t:s0 tclass=chr_file
>>> type=1400 audit(1280174589.476:8): avc:  denied  { read } for  pid=1
>>> comm="systemd" name="autofs" dev=devtmpfs ino=9482
>>> scontext=system_u:system_r:init_t:s0
>>> tcontext=system_u:object_r:device_t:s0 tclass=chr_file
>>>
>>> Lennart, we talked about this earlier.  I think this is caused by the
>>> modprobe calls to create /dev/autofs.  Since udev is not created at the
>>> point that init loads the kernel modules, the devices get created with
>>> the wrong label.  Once udev starts the labels get fixed.
>>>
>>> I can allow init_t to read device_t chr_files.
>>
>> Hmm, I think a cleaner fix would be to make systemd relabel this device
>> properly before accessing it? Given that this is only one device this
>> should not be a problem for us to maintain, I think? How would the
>> fixing of the label work? Would we have to spawn restorecon for this, or
>> can we actually do this in C without too much work?
>
> I guess we can just do what udev is doing, and call setfilecon(), with
> a context of an earlier matchpathcon().
>
> Kay
> _______________________________________________
> systemd-devel mailing list
> systemd-devel@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/systemd-devel

Here is the updated patch with a fix for the labeling of /dev/autofs
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gIEAmwRmRcLvGqYtwQaZ3WKIg8wmrwNk
=pC2e

8 files changed, 293 insertions, 99 deletions

diff --git a/configure.ac b/configure.ac
index 14622e47a0..65c8af0115 100644
--- a/configure.ac
+++ b/configure.ac
@@ -105,15 +105,26 @@ PKG_CHECK_MODULES(DBUS, [ dbus-1 >= 1.3.2 ])
 AC_SUBST(DBUS_CFLAGS)
 AC_SUBST(DBUS_LIBS)
 
-PKG_CHECK_MODULES(SELINUX, [ libselinux ])
-AC_SUBST(SELINUX_CFLAGS)
-AC_SUBST(SELINUX_LIBS)
-AC_SEARCH_LIBS([is_selinux_enabled], [selinux], [], [AC_MSG_ERROR([*** libselinux library not found])])
-
 PKG_CHECK_MODULES(DBUSGLIB, [ dbus-glib-1 ])
 AC_SUBST(DBUSGLIB_CFLAGS)
 AC_SUBST(DBUSGLIB_LIBS)
 
+have_selinux=no
+AC_ARG_ENABLE(selinux, AS_HELP_STRING([--disable-selinux], [Disable optional SELINUX support]))
+if test "x$enable_selinux" != "xno"; then
+	# not using PKG_CHECK_MODULES as for some reason libselinux didn't
+	# install any pkg-config modules here
+	AC_SEARCH_LIBS([getcon], [selinux],
+                [AC_DEFINE(HAVE_SELINUX, 1, [Define if SELINUX is available]) have_selinux=yes],
+		have_selinux=no)
+        AC_SUBST(SELINUX_CFLAGS)
+        AC_SUBST(SELINUX_LIBS)
+        if test "x$have_selinux" = xno -a "x$enable_selinux" = xyes; then
+                AC_MSG_ERROR([*** selinux support requested but libraries not found])
+        fi
+fi
+AM_CONDITIONAL(HAVE_SELINUX, [test "$have_selinux" = "yes"])
+
 AC_ARG_ENABLE([tcpwrap],
         AS_HELP_STRING([--disable-tcpwrap],[Disable optional TCP wrappers support]),
                 [case "${enableval}" in
diff --git a/src/automount.c b/src/automount.c
index 213b178eae..3a69cf9b4c 100644
--- a/src/automount.c
+++ b/src/automount.c
@@ -304,6 +304,8 @@ static int open_dev_autofs(Manager *m) {
         if (m->dev_autofs_fd >= 0)
                 return m->dev_autofs_fd;
 
+	label_fix("/dev/autofs");
+
         if ((m->dev_autofs_fd = open("/dev/autofs", O_CLOEXEC|O_RDONLY)) < 0) {
                 log_error("Failed to open /dev/autofs: %s", strerror(errno));
                 return -errno;
diff --git a/src/main.c b/src/main.c
index e67d2225bd..36dea9b3c6 100644
--- a/src/main.c
+++ b/src/main.c
@@ -836,6 +836,9 @@ int main(int argc, char *argv[]) {
                 return 1;
         }
 
+        if (label_init() < 0)
+                goto finish;
+
         log_show_color(isatty(STDERR_FILENO) > 0);
         log_show_location(false);
         log_set_max_level(LOG_INFO);
@@ -1113,5 +1116,7 @@ finish:
         if (getpid() == 1)
                 freeze();
 
+        label_finish();
+
         return retval;
 }
diff --git a/src/socket-util.c b/src/socket-util.c
index 3a00fcf43f..2af8563965 100644
--- a/src/socket-util.c
+++ b/src/socket-util.c
@@ -29,7 +29,6 @@
 #include <net/if.h>
 #include <sys/types.h>
 #include <sys/stat.h>
-#include <selinux/selinux.h>
 
 #include "macro.h"
 #include "util.h"
@@ -306,7 +305,7 @@ int socket_address_listen(
                 bool free_bind,
                 mode_t directory_mode,
                 mode_t socket_mode,
-                security_context_t scon,
+                const char *label,
                 int *ret) {
 
         int r, fd, one;
@@ -316,16 +315,14 @@ int socket_address_listen(
         if ((r = socket_address_verify(a)) < 0)
                 return r;
 
-        if (setsockcreatecon(scon) < 0) {
-                log_error("Failed to set SELinux context (%s) on socket: %m", scon);
-                if (security_getenforce() == 1)
-                        return -errno;
-        }
+        r = label_socket_set(label);
+        if (r < 0)
+                return r;
 
         fd = socket(socket_address_family(a), a->type | SOCK_NONBLOCK | SOCK_CLOEXEC, 0);
         r = fd < 0 ? -errno : 0;
 
-        setsockcreatecon(NULL);
+        label_socket_clear();
 
         if (r < 0)
                 return r;
diff --git a/src/socket-util.h b/src/socket-util.h
index 841570f002..86c9e47809 100644
--- a/src/socket-util.h
+++ b/src/socket-util.h
@@ -26,7 +26,6 @@
 #include <netinet/in.h>
 #include <sys/un.h>
 #include <net/if.h>
-#include <selinux/selinux.h>
 
 #include "macro.h"
 #include "util.h"
@@ -72,7 +71,7 @@ int socket_address_listen(
                 bool free_bind,
                 mode_t directory_mode,
                 mode_t socket_mode,
-                security_context_t scon,
+                const char *label,
                 int *ret);
 
 bool socket_address_is(const SocketAddress *a, const char *s, int type);
diff --git a/src/socket.c b/src/socket.c
index 2da3215a3d..2a5270f336 100644
--- a/src/socket.c
+++ b/src/socket.c
@@ -27,7 +27,6 @@
 #include <sys/epoll.h>
 #include <signal.h>
 #include <arpa/inet.h>
-#include <selinux/selinux.h>
 
 #include "unit.h"
 #include "socket.h"
@@ -653,89 +652,25 @@ 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,
-                security_context_t scon,
+                const char *label,
                 int *_fd) {
 
         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);
 
-        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;
-        }
+        if ((r = label_fifofile_set(label, path)) < 0)
+                goto fail;
 
         /* Enforce the right access mode for the fifo */
         old_mask = umask(~ socket_mode);
@@ -756,7 +691,7 @@ static int fifo_address_create(
                 goto fail;
         }
 
-        setfscreatecon(NULL);
+        label_file_clear();
 
         if (fstat(fd, &st) < 0) {
                 r = -errno;
@@ -776,7 +711,8 @@ static int fifo_address_create(
         return 0;
 
 fail:
-        setfscreatecon(NULL);
+        label_file_clear();
+
         if (fd >= 0)
                 close_nointr_nofail(fd);
 
@@ -786,20 +722,16 @@ fail:
 static int socket_open_fds(Socket *s) {
         SocketPort *p;
         int r;
-        security_context_t scon = NULL;
+        char *label = NULL;
 
         assert(s);
 
         if ((r = socket_instantiate_service(s)) < 0)
                 return r;
 
-        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;
-        }
+        if ((r = label_get_socket_label_from_exe(s->service->exec_command[SERVICE_EXEC_START]->path, &label)) < 0)
+                return r;
 
-        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)
@@ -815,7 +747,7 @@ static int socket_open_fds(Socket *s) {
                                              s->free_bind,
                                              s->directory_mode,
                                              s->socket_mode,
-                                             scon,
+                                             label,
                                              &p->fd)) < 0)
                                 goto rollback;
 
@@ -827,7 +759,7 @@ static int socket_open_fds(Socket *s) {
                                              p->path,
                                              s->directory_mode,
                                              s->socket_mode,
-                                             scon,
+                                             label,
                                              &p->fd)) < 0)
                                 goto rollback;
 
@@ -837,12 +769,12 @@ static int socket_open_fds(Socket *s) {
                         assert_not_reached("Unknown port type");
         }
 
-        freecon(scon);
+        label_free(label);
         return 0;
 
 rollback:
         socket_close_fds(s);
-        freecon(scon);
+        label_free(label);
         return r;
 }
 
diff --git a/src/util.c b/src/util.c
index da8a6c3336..2279efac49 100644
--- a/src/util.c
+++ b/src/util.c
@@ -56,6 +56,244 @@
 #include "log.h"
 #include "strv.h"
 
+#if HAVE_SELINUX
+#include <selinux/selinux.h>
+#include <selinux/label.h>
+
+static struct selabel_handle *label_hnd = NULL;
+
+static inline int use_selinux(void) {
+        static int use_selinux_ind = -1;
+
+        if (use_selinux_ind == -1)
+                use_selinux_ind = (is_selinux_enabled() == 1);
+
+        return use_selinux_ind;
+}
+
+static int label_get_file_label_from_path(
+                const char *label,
+                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((security_context_t) label, dir_con, sclass, fcon);
+        }
+        if (r < 0)
+                r = -errno;
+
+        freecon(dir_con);
+        return r;
+}
+
+#endif
+
+int label_init(void) {
+        int r = 0;
+
+#if HAVE_SELINUX
+        if (use_selinux()) {
+                label_hnd = selabel_open(SELABEL_CTX_FILE, NULL, 0);
+                if (!label_hnd) {
+                        log_full(security_getenforce() == 1 ? LOG_ERR : LOG_DEBUG, "Failed to initialize SELinux context: %m");
+                        r = (security_getenforce() == 1) ? -errno : 0;
+                }
+        }
+#endif
+
+        return r;
+}
+
+int label_fix(const char *path) {
+        int r = 0;
+#if HAVE_SELINUX
+        struct stat st;
+        security_context_t fcon;
+        if (use_selinux()) {
+                r = lstat(path, &st);
+
+                if (r == 0) {
+                        r = selabel_lookup_raw(label_hnd, &fcon, path, st.st_mode);
+
+                        if (r == 0) {
+                                r = setfilecon(path, fcon);
+                                freecon(fcon);
+                        }
+                }
+                if (r < 0) {
+                        log_error("Unable to fix label of %s: %m", path);
+                        r = (security_getenforce() == 1) ? -errno : 0;
+                }
+        }
+#endif
+        return r;
+}
+
+void label_finish(void) {
+
+#if HAVE_SELINUX
+        if (use_selinux())
+                selabel_close(label_hnd);
+#endif
+
+}
+
+int label_get_socket_label_from_exe(
+        const char *exe,
+        char **label) {
+        int r = 0;
+
+#if HAVE_SELINUX
+        security_context_t mycon = NULL, fcon = NULL;
+        security_class_t sclass;
+
+        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, (security_context_t *) label);
+        if (r == 0)
+                log_debug("SELinux Socket context for %s will be set to %s", exe, *label);
+
+fail:
+        if (r< 0 && security_getenforce() == 1)
+                r = -errno;
+
+        freecon(mycon);
+        freecon(fcon);
+#endif
+
+        return r;
+}
+
+int label_fifofile_set(const char *label, const char *path) {
+        int r = 0;
+
+#if HAVE_SELINUX
+        security_context_t filecon = NULL;
+        if (use_selinux() && label) {
+                if (((r = label_get_file_label_from_path(label, path, "fifo_file", &filecon)) == 0)) {
+                        if ((r = setfscreatecon(filecon)) < 0) {
+                                log_error("Failed to set SELinux file context (%s) on %s: %m", label, path);
+                                r = -errno;
+                        }
+
+                        freecon(filecon);
+                }
+
+                if (r < 0  && security_getenforce() == 0)
+                        r = 0;
+        }
+#endif
+
+        return r;
+}
+
+int label_socket_set(const char *label) {
+
+#if HAVE_SELINUX
+        if (use_selinux() && setsockcreatecon((security_context_t) label) < 0) {
+                log_error("Failed to set SELinux context (%s) on socket: %m", label);
+                if (security_getenforce() == 1)
+                        return -errno;
+        }
+#endif
+
+        return 0;
+}
+
+void label_file_clear(void) {
+
+#if HAVE_SELINUX
+        if (use_selinux())
+                setfscreatecon(NULL);
+#endif
+
+        return;
+}
+
+void label_free(const char *label) {
+
+#if HAVE_SELINUX
+        if (use_selinux())
+                freecon((security_context_t) label);
+#endif
+
+        return;
+}
+
+void label_socket_clear(void) {
+
+#if HAVE_SELINUX
+        if (use_selinux())
+                setsockcreatecon(NULL);
+#endif
+
+        return;
+}
+
+static int label_mkdir(
+        const char *path,
+        mode_t mode) {
+
+#if HAVE_SELINUX
+        int r;
+        security_context_t fcon = NULL;
+
+        if (use_selinux()) {
+                if (path[0] == '/') {
+                        r = selabel_lookup_raw(label_hnd, &fcon, path, mode);
+                }
+                else {
+                        char *cwd = NULL;
+                        char *newpath = NULL;
+                        cwd = getcwd(NULL,0);
+                        if ((! cwd) || (asprintf(&newpath, "%s/%s",cwd,path) < 0)) {
+                                free(cwd);
+                                return -errno;
+                        }
+                        r = selabel_lookup_raw(label_hnd, &fcon, newpath, mode);
+                        free(cwd);
+                        free(newpath);
+                }
+
+                if (r == 0)
+                        r = setfscreatecon(fcon);
+
+                if ((r < 0) && (errno != ENOENT)) {
+                        log_error("Failed to set security context %s for %s", fcon, path);
+
+                        if (security_getenforce() == 1)
+                                goto finish;
+                }
+        }
+        r = mkdir(path, mode);
+
+finish:
+        if (use_selinux()) {
+                setfscreatecon(NULL);
+                freecon(fcon);
+        }
+
+        return r;
+#else
+        return mkdir(path, mode);
+#endif
+}
+
 bool streq_ptr(const char *a, const char *b) {
 
         /* Like streq(), but tries to make sense of NULL pointers */
@@ -969,7 +1207,7 @@ char *file_in_same_dir(const char *path, const char *filename) {
 int safe_mkdir(const char *path, mode_t mode, uid_t uid, gid_t gid) {
         struct stat st;
 
-        if (mkdir(path, mode) >= 0)
+        if (label_mkdir(path, mode) >= 0)
                 if (chmod_and_chown(path, mode, uid, gid) < 0)
                         return -errno;
 
@@ -1012,7 +1250,7 @@ int mkdir_parents(const char *path, mode_t mode) {
                 if (!(t = strndup(path, e - path)))
                         return -ENOMEM;
 
-                r = mkdir(t, mode);
+                r = label_mkdir(t, mode);
                 free(t);
 
                 if (r < 0 && errno != EEXIST)
@@ -1028,7 +1266,7 @@ int mkdir_p(const char *path, mode_t mode) {
         if ((r = mkdir_parents(path, mode)) < 0)
                 return r;
 
-        if (mkdir(path, mode) < 0 && errno != EEXIST)
+        if (label_mkdir(path, mode) < 0 && errno != EEXIST)
                 return -errno;
 
         return 0;
diff --git a/src/util.h b/src/util.h
index 782adb8348..b097dc9b7b 100644
--- a/src/util.h
+++ b/src/util.h
@@ -360,4 +360,14 @@ int ip_tos_from_string(const char *s);
 const char *signal_to_string(int i);
 int signal_from_string(const char *s);
 
+int label_init(void);
+int label_fix(const char *path);
+void label_finish(void);
+int label_socket_set(const char *label);
+void label_socket_clear(void);
+int label_fifofile_set(const char *label, const char *path);
+void label_file_clear(void);
+void label_free(const char *label);
+int label_get_socket_label_from_exe(const char *exe, char **label);
+
 #endif