diff --git a/src/core/namespace.c b/src/core/namespace.c index 0c163abb68..e138d3ba02 100644 --- a/src/core/namespace.c +++ b/src/core/namespace.c @@ -565,14 +565,14 @@ static void drop_outside_root(const char *root_directory, MountEntry *m, unsigne *n = t - m; } -static int clone_device_node(const char *d, const char *temporary_mount) { +static int clone_device_node(const char *d, const char *temporary_mount, bool *make_devnode) { const char *dn; struct stat st; int r; if (stat(d, &st) < 0) { if (errno == ENOENT) - return 0; + return -ENXIO; return -errno; } @@ -581,17 +581,41 @@ static int clone_device_node(const char *d, const char *temporary_mount) { return -EINVAL; if (st.st_rdev == 0) - return 0; + return -ENXIO; dn = strjoina(temporary_mount, d); - mac_selinux_create_file_prepare(d, st.st_mode); - r = mknod(dn, st.st_mode, st.st_rdev); - mac_selinux_create_file_clear(); - if (r < 0) - return log_debug_errno(errno, "mknod failed for %s: %m", d); + if (*make_devnode) { + mac_selinux_create_file_prepare(d, st.st_mode); + r = mknod(dn, st.st_mode, st.st_rdev); + mac_selinux_create_file_clear(); - return 1; + if (r == 0) + return 0; + if (errno != EPERM) + return log_debug_errno(errno, "mknod failed for %s: %m", d); + + *make_devnode = false; + } + + /* We're about to fallback to bind-mounting the device + * node. So create a dummy bind-mount target. */ + mac_selinux_create_file_prepare(d, 0); + r = mknod(dn, S_IFREG, 0); + mac_selinux_create_file_clear(); + + if (r < 0 && errno != EEXIST) + return log_debug_errno(errno, "mknod fallback failed for %s: %m", d); + + /* Fallback to bind-mounting: + * The assumption here is that all used device nodes carry standard + * properties. Specifically, the devices nodes we bind-mount should + * either be owned by root:root or root:tty (e.g. /dev/tty, /dev/ptmx) + * and should not carry ACLs. */ + if (mount(d, dn, NULL, MS_BIND, NULL) < 0) + return log_debug_errno(errno, "mount failed for %s: %m", d); + + return 0; } static int mount_private_dev(MountEntry *m) { @@ -605,6 +629,7 @@ static int mount_private_dev(MountEntry *m) { char temporary_mount[] = "/tmp/namespace-dev-XXXXXX"; const char *d, *dev = NULL, *devpts = NULL, *devshm = NULL, *devhugepages = NULL, *devmqueue = NULL, *devlog = NULL, *devptmx = NULL; + bool can_mknod = true; _cleanup_umask_ mode_t u; int r; @@ -645,13 +670,9 @@ static int mount_private_dev(MountEntry *m) { goto fail; } } else { - r = clone_device_node("/dev/ptmx", temporary_mount); + r = clone_device_node("/dev/ptmx", temporary_mount, &can_mknod); if (r < 0) goto fail; - if (r == 0) { - r = -ENXIO; - goto fail; - } } devshm = strjoina(temporary_mount, "/dev/shm"); @@ -674,8 +695,9 @@ static int mount_private_dev(MountEntry *m) { (void) symlink("/run/systemd/journal/dev-log", devlog); NULSTR_FOREACH(d, devnodes) { - r = clone_device_node(d, temporary_mount); - if (r < 0) + r = clone_device_node(d, temporary_mount, &can_mknod); + /* ENXIO means the the *source* is not a device file, skip creation in that case */ + if (r < 0 && r != -ENXIO) goto fail; }