/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include <sys/stat.h> #include <sys/statvfs.h> #include <sys/vfs.h> #include "binfmt-util.h" #include "errno-util.h" #include "fd-util.h" #include "fileio.h" #include "fs-util.h" #include "missing_magic.h" #include "stat-util.h" int binfmt_mounted(void) { _cleanup_close_ int fd = -EBADF; int r; fd = RET_NERRNO(open("/proc/sys/fs/binfmt_misc", O_CLOEXEC | O_DIRECTORY | O_PATH)); if (fd == -ENOENT) return false; if (fd < 0) return fd; r = fd_is_fs_type(fd, BINFMTFS_MAGIC); if (r <= 0) return r; return access_fd(fd, W_OK) >= 0; } int disable_binfmt(void) { int r; /* Flush out all rules. This is important during shutdown to cover for rules using "F", since those * might pin a file and thus block us from unmounting stuff cleanly. * * We are a bit careful here, since binfmt_misc might still be an autofs which we don't want to * trigger. */ r = binfmt_mounted(); if (r < 0) return log_warning_errno(r, "Failed to determine whether binfmt_misc is mounted: %m"); if (r == 0) { log_debug("binfmt_misc is not mounted in read-write mode, not detaching entries."); return 0; } r = write_string_file("/proc/sys/fs/binfmt_misc/status", "-1", WRITE_STRING_FILE_DISABLE_BUFFER); if (r < 0) return log_warning_errno(r, "Failed to unregister binfmt_misc entries: %m"); log_debug("Unregistered all remaining binfmt_misc entries."); return 0; }