Merge pull request #3673 from brauner/2021-02-15/nesting

src/lxc/attach.c

@@ -27,7 +27,8 @@
 #include "af_unix.h"
 #include "attach.h"
 #include "caps.h"
-#include "cgroup.h"
+#include "cgroups/cgroup.h"
+#include "cgroups/cgroup_utils.h"
 #include "commands.h"
 #include "conf.h"
 #include "config.h"

src/lxc/cgroups/cgfsng.c

@@ -1709,16 +1709,16 @@ __cgfsng_ops static void cgfsng_payload_finalize(struct cgroup_ops *ops)
 }
 
 /* cgroup-full:* is done, no need to create subdirs */
-static inline bool cg_mount_needs_subdirs(int type)
+static inline bool cg_mount_needs_subdirs(int cg_flags)
 {
-	return !(type >= LXC_AUTO_CGROUP_FULL_RO);
+	return !(cg_flags >= LXC_AUTO_CGROUP_FULL_RO);
 }
 
 /* After $rootfs/sys/fs/container/controller/the/cg/path has been created,
  * remount controller ro if needed and bindmount the cgroupfs onto
  * control/the/cg/path.
  */
-static int cg_legacy_mount_controllers(int type, struct hierarchy *h,
+static int cg_legacy_mount_controllers(int cg_flags, struct hierarchy *h,
 				       char *controllerpath, char *cgpath,
 				       const char *container_cgroup)
 {
@@ -1726,7 +1726,7 @@ static int cg_legacy_mount_controllers(int type, struct hierarchy *h,
 	int ret, remount_flags;
 	int flags = MS_BIND;
 
-	if (type == LXC_AUTO_CGROUP_RO || type == LXC_AUTO_CGROUP_MIXED) {
+	if ((cg_flags & LXC_AUTO_CGROUP_RO) || (cg_flags & LXC_AUTO_CGROUP_MIXED)) {
 		ret = mount(controllerpath, controllerpath, "cgroup", MS_BIND, NULL);
 		if (ret < 0)
 			return log_error_errno(-1, errno, "Failed to bind mount \"%s\" onto \"%s\"",
@@ -1746,7 +1746,7 @@ static int cg_legacy_mount_controllers(int type, struct hierarchy *h,
 
 	sourcepath = must_make_path(h->mountpoint, h->container_base_path,
 				    container_cgroup, NULL);
-	if (type == LXC_AUTO_CGROUP_RO)
+	if ((cg_flags & LXC_AUTO_CGROUP_RO))
 		flags |= MS_RDONLY;
 
 	ret = mount(sourcepath, cgpath, "cgroup", flags, NULL);
@@ -1768,15 +1768,15 @@ static int cg_legacy_mount_controllers(int type, struct hierarchy *h,
 	return 0;
 }
 
-/* __cg_mount_direct
+/* __cgroupfs_mount
  *
  * Mount cgroup hierarchies directly without using bind-mounts. The main
  * uses-cases are mounting cgroup hierarchies in cgroup namespaces and mounting
  * cgroups for the LXC_AUTO_CGROUP_FULL option.
  */
-static int __cg_mount_direct(int type, struct hierarchy *h,
-			     struct lxc_rootfs *rootfs,
-			     int dfd_mnt_cgroupfs, const char *hierarchy_mnt)
+static int __cgroupfs_mount(int cg_flags, struct hierarchy *h,
+			    struct lxc_rootfs *rootfs, int dfd_mnt_cgroupfs,
+			    const char *hierarchy_mnt)
 {
 	__do_close int fd_fs = -EBADF;
 	unsigned int flags = 0;
@@ -1791,7 +1791,8 @@ static int __cg_mount_direct(int type, struct hierarchy *h,
 	flags |= MOUNT_ATTR_NODEV;
 	flags |= MOUNT_ATTR_RELATIME;
 
-	if (type == LXC_AUTO_CGROUP_RO || type == LXC_AUTO_CGROUP_FULL_RO)
+	if ((cg_flags & LXC_AUTO_CGROUP_RO) ||
+	    (cg_flags & LXC_AUTO_CGROUP_FULL_RO))
 		flags |= MOUNT_ATTR_RDONLY;
 
 	if (is_unified_hierarchy(h)) {
@@ -1847,31 +1848,32 @@ static int __cg_mount_direct(int type, struct hierarchy *h,
 	return 0;
 }
 
-static inline int cg_mount_in_cgroup_namespace(int type, struct hierarchy *h,
+static inline int cgroupfs_mount(int cg_flags, struct hierarchy *h,
 				 struct lxc_rootfs *rootfs,
-					       int dfd_mnt_cgroupfs,
-					       const char *hierarchy_mnt)
+				 int dfd_mnt_cgroupfs, const char *hierarchy_mnt)
 {
-	return __cg_mount_direct(type, h, rootfs, dfd_mnt_cgroupfs, hierarchy_mnt);
+	return __cgroupfs_mount(cg_flags, h, rootfs, dfd_mnt_cgroupfs, hierarchy_mnt);
 }
 
-static inline int cg_mount_cgroup_full(int type, struct hierarchy *h,
+static inline int cgroupfs_bind_mount(int cg_flags, struct hierarchy *h,
 				      struct lxc_rootfs *rootfs,
 				      int dfd_mnt_cgroupfs,
 				      const char *hierarchy_mnt)
 {
-	if (type < LXC_AUTO_CGROUP_FULL_RO || type > LXC_AUTO_CGROUP_FULL_MIXED)
+	if (!(cg_flags & LXC_AUTO_CGROUP_FULL_RO) &&
+	    !(cg_flags & LXC_AUTO_CGROUP_FULL_MIXED))
 		return 0;
 
-	return __cg_mount_direct(type, h, rootfs, dfd_mnt_cgroupfs, hierarchy_mnt);
+	return __cgroupfs_mount(cg_flags, h, rootfs, dfd_mnt_cgroupfs, hierarchy_mnt);
 }
 
 __cgfsng_ops static bool cgfsng_mount(struct cgroup_ops *ops,
-				      struct lxc_conf *conf, int type)
+				      struct lxc_handler *handler, int cg_flags)
 {
 	__do_close int dfd_mnt_cgroupfs = -EBADF, fd_fs = -EBADF;
 	__do_free char *cgroup_root = NULL;
-	bool has_cgns = false, wants_force_mount = false;
+	bool in_cgroup_ns = false, wants_force_mount = false;
+	struct lxc_conf *conf = handler->conf;
 	struct lxc_rootfs *rootfs = &conf->rootfs;
 	const char *rootfs_mnt = get_rootfs_mnt(rootfs);
 	int ret;
@@ -1885,13 +1887,11 @@ __cgfsng_ops static bool cgfsng_mount(struct cgroup_ops *ops,
 	if (!conf)
 		return ret_set_errno(false, EINVAL);
 
-	if ((type & LXC_AUTO_CGROUP_MASK) == 0)
-		return true;
+	if ((cg_flags & LXC_AUTO_CGROUP_MASK) == 0)
+		return log_trace(true, "No cgroup mounts requested");
 
-	if (type & LXC_AUTO_CGROUP_FORCE) {
-		type &= ~LXC_AUTO_CGROUP_FORCE;
+	if (cg_flags & LXC_AUTO_CGROUP_FORCE)
 		wants_force_mount = true;
-	}
 
 	if (!wants_force_mount) {
 		wants_force_mount = !lxc_wants_cap(CAP_SYS_ADMIN, conf);
@@ -1910,14 +1910,30 @@ __cgfsng_ops static bool cgfsng_mount(struct cgroup_ops *ops,
 			wants_force_mount = true;
 	}
 
-	has_cgns = cgns_supported();
-	if (has_cgns && !wants_force_mount)
-		return true;
+	if (cgns_supported() && container_uses_namespace(handler, CLONE_NEWCGROUP)) {
+		in_cgroup_ns = true;
+		/*
+		 * When cgroup namespaces are supported and used by the
+		 * container the LXC_AUTO_CGROUP_MIXED and
+		 * LXC_AUTO_CGROUP_FULL_MIXED auto mount options don't apply
+		 * since the parent directory of the container's cgroup is not
+		 * accessible to the container.
+		 */
+		cg_flags &= ~LXC_AUTO_CGROUP_MIXED;
+		cg_flags &= ~LXC_AUTO_CGROUP_FULL_MIXED;
+	}
+
+	if (in_cgroup_ns && !wants_force_mount)
+		return log_trace(true, "Mounting cgroups not requested or needed");
 
-	if (type == LXC_AUTO_CGROUP_NOSPEC)
-		type = LXC_AUTO_CGROUP_MIXED;
-	else if (type == LXC_AUTO_CGROUP_FULL_NOSPEC)
-		type = LXC_AUTO_CGROUP_FULL_MIXED;
+	/*
+	 * Fallback to a mixed layout when the user did not specify what cgroup
+	 * layout they want.
+	 */
+	if ((cg_flags & LXC_AUTO_CGROUP_NOSPEC))
+		cg_flags = LXC_AUTO_CGROUP_MIXED;
+	else if (cg_flags & LXC_AUTO_CGROUP_FULL_NOSPEC)
+		cg_flags = LXC_AUTO_CGROUP_FULL_MIXED;
 
 	/* This is really the codepath that we want. */
 	if (pure_unified_layout(ops)) {
@@ -1929,16 +1945,70 @@ __cgfsng_ops static bool cgfsng_mount(struct cgroup_ops *ops,
 			return log_error_errno(-errno, errno, "Failed to open %d(%s)",
 					       rootfs->dfd_mnt, DEFAULT_CGROUP_MOUNTPOINT_RELATIVE);
 
-		if (has_cgns && wants_force_mount) {
 		/*
-			 * If cgroup namespaces are supported but the container
-			 * will not have CAP_SYS_ADMIN after it has started we
-			 * need to mount the cgroups manually.
+		 * If cgroup namespaces are supported but the container will
+		 * not have CAP_SYS_ADMIN after it has started we need to mount
+		 * the cgroups manually.
+		 *
+		 * Note that here we know that wants_force_mount is true.
+		 * Otherwise we would've returned early above.
+		 */
+		if (in_cgroup_ns) {
+			/*
+			 *  1. cgroup:rw:force    -> Mount the cgroup2 filesystem.
+			 *  2. cgroup:ro:force    -> Mount the cgroup2 filesystem read-only.
+			 *  3. cgroup:mixed:force -> See comment above how this
+			 *                           does not apply so
+			 *                           cgroup:mixed is equal to
+			 *                           cgroup:rw when cgroup
+			 *                           namespaces are supported.
+
+			 *  4. cgroup:rw    -> No-op; init system responsible for mounting.
+			 *  5. cgroup:ro    -> No-op; init system responsible for mounting.
+			 *  6. cgroup:mixed -> No-op; init system responsible for mounting.
+                         *
+			 *  7. cgroup-full:rw    -> Not supported.
+			 *  8. cgroup-full:ro    -> Not supported.
+			 *  9. cgroup-full:mixed -> Not supported.
+
+			 * 10. cgroup-full:rw:force    -> Not supported.
+			 * 11. cgroup-full:ro:force    -> Not supported.
+			 * 12. cgroup-full:mixed:force -> Not supported.
+			 */
+			ret = cgroupfs_mount(cg_flags, ops->unified, rootfs, dfd_mnt_cgroupfs, "");
+			if (ret < 0)
+				return syserrno(false, "Failed to force mount cgroup filesystem in cgroup namespace");
+
+			return log_trace(true, "Force mounted cgroup filesystem in new cgroup namespace");
+		} else {
+			/*
+			 * Either no cgroup namespace supported (highly
+			 * unlikely unless we're dealing with a Frankenkernel.
+			 * Or the user requested to keep the cgroup namespace
+			 * of the host or another container.
+			 */
+			if (wants_force_mount) {
+				/*
+				 * 1. cgroup:rw:force    -> Bind-mount the cgroup2 filesystem writable.
+				 * 2. cgroup:ro:force    -> Bind-mount the cgroup2 filesystem read-only.
+				 * 3. cgroup:mixed:force -> bind-mount the cgroup2 filesystem and
+				 *                          and make the parent directory of the
+				 *                          container's cgroup read-only but the
+				 *                          container's cgroup writable.
+                                 *
+				 * 10. cgroup-full:rw:force    ->
+				 * 11. cgroup-full:ro:force    ->
+				 * 12. cgroup-full:mixed:force ->
 				 */
-			return cg_mount_in_cgroup_namespace(type, ops->unified, rootfs, dfd_mnt_cgroupfs, "") == 0;
+				errno = EOPNOTSUPP;
+				SYSWARN("Force-mounting the unified cgroup hierarchy without cgroup namespace support is currently not supported");
+			} else {
+				errno = EOPNOTSUPP;
+				SYSWARN("Mounting the unified cgroup hierarchy without cgroup namespace support is currently not supported");
+			}
 		}
 
-		return cg_mount_cgroup_full(type, ops->unified, rootfs, dfd_mnt_cgroupfs, "") == 0;
+		return syserrno(false, "Failed to mount cgroups");
 	}
 
 	/*
@@ -1994,13 +2064,13 @@ __cgfsng_ops static bool cgfsng_mount(struct cgroup_ops *ops,
 		if (ret < 0)
 			return log_error_errno(false, errno, "Failed to create cgroup mountpoint %d(%s)", dfd_mnt_cgroupfs, controller);
 
-		if (has_cgns && wants_force_mount) {
+		if (in_cgroup_ns && wants_force_mount) {
 			/*
 			 * If cgroup namespaces are supported but the container
 			 * will not have CAP_SYS_ADMIN after it has started we
 			 * need to mount the cgroups manually.
 			 */
-			ret = cg_mount_in_cgroup_namespace(type, h, rootfs, dfd_mnt_cgroupfs, controller);
+			ret = cgroupfs_mount(cg_flags, h, rootfs, dfd_mnt_cgroupfs, controller);
 			if (ret < 0)
 				return false;
 
@@ -2008,11 +2078,11 @@ __cgfsng_ops static bool cgfsng_mount(struct cgroup_ops *ops,
 		}
 
 		/* Here is where the ancient kernel section begins. */
-		ret = cg_mount_cgroup_full(type, h, rootfs, dfd_mnt_cgroupfs, controller);
+		ret = cgroupfs_bind_mount(cg_flags, h, rootfs, dfd_mnt_cgroupfs, controller);
 		if (ret < 0)
 			return false;
 
-		if (!cg_mount_needs_subdirs(type))
+		if (!cg_mount_needs_subdirs(cg_flags))
 			continue;
 
 		controllerpath = must_make_path(cgroup_root, controller, NULL);
@@ -2024,7 +2094,7 @@ __cgfsng_ops static bool cgfsng_mount(struct cgroup_ops *ops,
 		if (ret < 0)
 			return false;
 
-		ret = cg_legacy_mount_controllers(type, h, controllerpath, path2, ops->container_cgroup);
+		ret = cg_legacy_mount_controllers(cg_flags, h, controllerpath, path2, ops->container_cgroup);
 		if (ret < 0)
 			return false;
 	}

src/lxc/cgroups/cgroup.h

@@ -172,7 +172,7 @@ struct cgroup_ops {
 	bool (*chown)(struct cgroup_ops *ops, struct lxc_conf *conf);
 	bool (*attach)(struct cgroup_ops *ops, const struct lxc_conf *conf,
 		       const char *name, const char *lxcpath, pid_t pid);
-	bool (*mount)(struct cgroup_ops *ops, struct lxc_conf *conf, int type);
+	bool (*mount)(struct cgroup_ops *ops, struct lxc_handler *handler, int type);
 	bool (*devices_activate)(struct cgroup_ops *ops,
 				 struct lxc_handler *handler);
 	bool (*monitor_delegate_controllers)(struct cgroup_ops *ops);

src/lxc/cgroups/cgroup_utils.h

@@ -7,6 +7,7 @@
 #include <stdio.h>
 
 #include "compiler.h"
+#include "file_utils.h"
 
 /* Retrieve the cgroup version of a given entry from /proc/<pid>/mountinfo. */
 __hidden extern int get_cgroup_version(char *line);
@@ -32,4 +33,14 @@ __hidden extern int unified_cgroup_hierarchy(void);
 
 __hidden extern int unified_cgroup_fd(int fd);
 
+static inline bool cgns_supported(void)
+{
+	static int supported = -1;
+
+	if (supported == -1)
+		supported = file_exists("/proc/self/ns/cgroup");
+
+	return supported == 1;
+}
+
 #endif /* __LXC_CGROUP_UTILS_H */

src/lxc/conf.c

@@ -564,7 +564,7 @@ static int add_shmount_to_list(struct lxc_conf *conf)
 	return add_elem_to_mount_list(new_mount, conf);
 }
 
-static int lxc_mount_auto_mounts(struct lxc_conf *conf, int flags, struct lxc_handler *handler)
+static int lxc_mount_auto_mounts(struct lxc_handler *handler, int flags)
 {
 	int i, ret;
 	static struct {
@@ -608,6 +608,7 @@ static int lxc_mount_auto_mounts(struct lxc_conf *conf, int flags, struct lxc_ha
 		{ LXC_AUTO_SYS_MASK,  LXC_AUTO_SYS_MIXED,  NULL,                                             "%r/sys/devices/virtual/net", NULL,    MS_REMOUNT|MS_BIND|MS_NOSUID|MS_NODEV|MS_NOEXEC, NULL, false },
 		{ 0,                  0,                   NULL,                                             NULL,                         NULL,    0,                                               NULL, false }
 	};
+	struct lxc_conf *conf = handler->conf;
         struct lxc_rootfs *rootfs = &conf->rootfs;
         bool has_cap_net_admin;
 
@@ -703,7 +704,7 @@ static int lxc_mount_auto_mounts(struct lxc_conf *conf, int flags, struct lxc_ha
 		if (flags & LXC_AUTO_CGROUP_FORCE)
 			cg_flags |= LXC_AUTO_CGROUP_FORCE;
 
-		if (!handler->cgroup_ops->mount(handler->cgroup_ops, conf, cg_flags))
+		if (!handler->cgroup_ops->mount(handler->cgroup_ops, handler, cg_flags))
 			return log_error_errno(-1, errno, "Failed to mount \"/sys/fs/cgroup\"");
 	}
 
@@ -3432,7 +3433,7 @@ int lxc_setup(struct lxc_handler *handler)
 	/* Do automatic mounts (mainly /proc and /sys), but exclude those that
 	 * need to wait until other stuff has finished.
 	 */
-	ret = lxc_mount_auto_mounts(lxc_conf, lxc_conf->auto_mounts & ~LXC_AUTO_CGROUP_MASK, handler);
+	ret = lxc_mount_auto_mounts(handler, lxc_conf->auto_mounts & ~LXC_AUTO_CGROUP_MASK);
 	if (ret < 0)
 		return log_error(-1, "Failed to setup first automatic mounts");
 
@@ -3473,7 +3474,7 @@ int lxc_setup(struct lxc_handler *handler)
 	 * mounted. It is guaranteed to be mounted now either through
 	 * automatically or via fstab entries.
 	 */
-	ret = lxc_mount_auto_mounts(lxc_conf, lxc_conf->auto_mounts & LXC_AUTO_CGROUP_MASK, handler);
+	ret = lxc_mount_auto_mounts(handler, lxc_conf->auto_mounts & LXC_AUTO_CGROUP_MASK);
 	if (ret < 0)
 		return log_error(-1, "Failed to setup remaining automatic mounts");
 

src/lxc/conf.h

@@ -241,7 +241,7 @@ enum {
 	LXC_AUTO_CGROUP_NOSPEC        = 0x0B0, /* /sys/fs/cgroup (partial mount, r/w or mixed, depending on caps) */
 	LXC_AUTO_CGROUP_FULL_NOSPEC   = 0x0E0, /* /sys/fs/cgroup (full mount, r/w or mixed, depending on caps) */
 	LXC_AUTO_CGROUP_FORCE         = 0x100, /* mount cgroups even when cgroup namespaces are supported */
-	LXC_AUTO_CGROUP_MASK          = 0x1F0, /* all known cgroup options, doe not contain LXC_AUTO_CGROUP_FORCE */
+	LXC_AUTO_CGROUP_MASK          = 0x1F0, /* all known cgroup options */
 
 	LXC_AUTO_SHMOUNTS             = 0x200, /* shared mount point */
 	LXC_AUTO_SHMOUNTS_MASK        = 0x200, /* shared mount point mask */

src/lxc/log.h

@@ -494,6 +494,13 @@ __lxc_unused static inline void LXC_##LEVEL(struct lxc_log_locinfo* locinfo,	\
 		__internal_ret__;                             \
 	})
 
+#define syserrno(__ret__, format, ...)                        \
+	({                                                    \
+		typeof(__ret__) __internal_ret__ = (__ret__); \
+		SYSERROR(format, ##__VA_ARGS__);              \
+		__internal_ret__;                             \
+	})
+
 #define log_error(__ret__, format, ...)                       \
 	({                                                    \
 		typeof(__ret__) __internal_ret__ = (__ret__); \

src/lxc/lsm/apparmor.c

@@ -13,6 +13,7 @@
 #include <unistd.h>
 
 #include "caps.h"
+#include "cgroups/cgroup_utils.h"
 #include "conf.h"
 #include "config.h"
 #include "initutils.h"

src/lxc/start.c

@@ -27,7 +27,8 @@
 
 #include "af_unix.h"
 #include "caps.h"
-#include "cgroup.h"
+#include "cgroups/cgroup.h"
+#include "cgroups/cgroup_utils.h"
 #include "commands.h"
 #include "commands_utils.h"
 #include "compiler.h"

src/lxc/start.h

@@ -180,4 +180,10 @@ __hidden extern int __lxc_start(struct lxc_handler *, struct lxc_operations *, v
 __hidden extern int resolve_clone_flags(struct lxc_handler *handler);
 __hidden extern void lxc_expose_namespace_environment(const struct lxc_handler *handler);
 
+static inline bool container_uses_namespace(const struct lxc_handler *handler,
+					    unsigned int ns_flag)
+{
+	return (handler->ns_clone_flags & ns_flag);
+}
+
 #endif

src/lxc/utils.c

@@ -747,11 +747,6 @@ char *on_path(const char *cmd, const char *rootfs)
 	return NULL;
 }
 
-bool cgns_supported(void)
-{
-	return file_exists("/proc/self/ns/cgroup");
-}
-
 /* historically lxc-init has been under /usr/lib/lxc and under
  * /usr/lib/$ARCH/lxc.  It now lives as $prefix/sbin/init.lxc.
  */
@@ -1860,3 +1855,53 @@ bool multiply_overflow(int64_t base, uint64_t mult, int64_t *res)
 	*res = base * mult;
 	return true;
 }
+
+int print_r(int fd, const char *path)
+{
+	__do_close int dfd = -EBADF;
+	__do_closedir DIR *dir = NULL;
+	int ret = 0;
+	struct dirent *direntp;
+	struct stat st;
+
+	if (is_empty_string(path))
+		dfd = dup(fd);
+	else
+		dfd = openat(fd, path, O_CLOEXEC | O_DIRECTORY);
+	if (dfd < 0)
+		return -1;
+
+	dir = fdopendir(dfd);
+	if (!dir)
+		return -1;
+	/* Transfer ownership to fdopendir(). */
+	move_fd(dfd);
+
+	while ((direntp = readdir(dir))) {
+		if (!strcmp(direntp->d_name, ".") ||
+		    !strcmp(direntp->d_name, ".."))
+			continue;
+
+		ret = fstatat(dfd, direntp->d_name, &st, AT_SYMLINK_NOFOLLOW);
+		if (ret < 0 && errno != ENOENT)
+			break;
+
+		ret = 0;
+		if (S_ISDIR(st.st_mode))
+			ret = print_r(dfd, direntp->d_name);
+		else
+			INFO("mode(%o):uid(%d):gid(%d) -> %s/%s\n",
+			     (st.st_mode & ~S_IFMT), st.st_uid, st.st_gid, path,
+			     direntp->d_name);
+		if (ret < 0 && errno != ENOENT)
+			break;
+	}
+
+	ret = fstatat(fd, path, &st, AT_SYMLINK_NOFOLLOW);
+	if (ret)
+		return -1;
+	else
+		INFO("mode(%o):uid(%d):gid(%d) -> %s",
+		     (st.st_mode & ~S_IFMT), st.st_uid, st.st_gid, path);
+	return ret;
+}

src/lxc/utils.h

@@ -138,7 +138,6 @@ __hidden extern bool is_shared_mountpoint(const char *path);
 __hidden extern int detect_shared_rootfs(void);
 __hidden extern bool detect_ramfs_rootfs(void);
 __hidden extern char *on_path(const char *cmd, const char *rootfs);
-__hidden extern bool cgns_supported(void);
 __hidden extern char *choose_init(const char *rootfs);
 __hidden extern bool switch_to_ns(pid_t pid, const char *ns);
 __hidden extern char *get_template_path(const char *t);
@@ -244,5 +243,6 @@ __hidden extern int safe_mount_beneath(const char *beneath, const char *src, con
 				       const char *fstype, unsigned int flags, const void *data);
 __hidden extern int safe_mount_beneath_at(int beneat_fd, const char *src, const char *dst,
 					  const char *fstype, unsigned int flags, const void *data);
+__hidden __lxc_unused int print_r(int fd, const char *path);
 
 #endif /* __LXC_UTILS_H */

src/tests/lxc_raw_clone.c

@@ -37,6 +37,7 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 
+#include "cgroups/cgroup_utils.h"
 #include "lxctest.h"
 #include "namespace.h"
 #include "process_utils.h"