3  *  linux/fs/file.c
17 #include <linux/file.h>
75 	if (WARN_ONCE(cnt >= FILE_REF_RELEASED, "imbalanced put on file reference count")) {  in __file_ref_put()
116  * space if any.  This does not copy the file pointers.  Called with the files
133  * Copy all file descriptors from the old table to the new, expanded table and
142 	cpy = ofdt->max_fds * sizeof(struct file *);  in copy_fdtable()
143 	set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *);  in copy_fdtable()
199 	data = kvmalloc_array(nr, sizeof(struct file *), GFP_KERNEL_ACCOUNT);  in alloc_fdtable()
226  * Expand the file descriptor table.
263  * This function will expand the file structures, if the requested size exceeds
366 	struct file **old_fds, **new_fds;  in dup_fd()
427 	 * the file can show up as we are walking the array below.  in dup_fd()
433 	 * ref the file if we see it and mark the fd slot as unused otherwise.  in dup_fd()
436 		struct file *f = rcu_dereference_raw(*old_fds++);  in dup_fd()
447 	memset(new_fds, 0, (new_fdt->max_fds - open_files) * sizeof(struct file *));  in dup_fd()
472 				struct file *file = fdt->fd[i];  in close_files()  local
473 				if (file) {  in close_files()
474 					filp_close(file, files);  in close_files()
548  * allocate a file descriptor, mark it busy.
624  * Install a file pointer in the fd array.
627  * setting the open_fds bitmap and installing the file in the file
629  * installing a file in the array before us.  We need to detect this and
630  * fput() the struct file we are about to overwrite in this case.
635  * This consumes the "file" refcount, so callers should treat it
636  * as if they had called fput(file).
639 void fd_install(unsigned int fd, struct file *file)  in fd_install()  argument
644 	if (WARN_ON_ONCE(unlikely(file->f_mode & FMODE_BACKING)))  in fd_install()
654 		rcu_assign_pointer(fdt->fd[fd], file);  in fd_install()
662 	rcu_assign_pointer(fdt->fd[fd], file);  in fd_install()
669  * file_close_fd_locked - return file associated with fd
670  * @files: file struct to retrieve file from
671  * @fd: file descriptor to retrieve file for
677  * Returns: The file associated with @fd (NULL if @fd is not open)
679 struct file *file_close_fd_locked(struct files_struct *files, unsigned fd)  in file_close_fd_locked()
682 	struct file *file;  in file_close_fd_locked()  local
690 	file = rcu_dereference_raw(fdt->fd[fd]);  in file_close_fd_locked()
691 	if (file) {  in file_close_fd_locked()
695 	return file;  in file_close_fd_locked()
701 	struct file *file;  in close_fd()  local
704 	file = file_close_fd_locked(files, fd);  in close_fd()
706 	if (!file)  in close_fd()
709 	return filp_close(file, files);  in close_fd()
715  * @fdt: File descriptor table.
743 	struct file *file;  in __range_close()  local
751 		file = file_close_fd_locked(files, fd);  in __range_close()
752 		if (file) {  in __range_close()
754 			filp_close(file, files);  in __range_close()
767  * sys_close_range() - Close all file descriptors in a given range.
769  * @fd:     starting file descriptor to close
770  * @max_fd: last file descriptor to close
773  * This closes a range of file descriptors. All file descriptors
775  * Currently, errors to close a given file descriptor are ignored.
794 		 * copy all of the file descriptors since they still want to  in SYSCALL_DEFINE3()
804 		 * We used to share our file descriptor table, and have now  in SYSCALL_DEFINE3()
818 		 * the new file descriptor table and drop the old one.  in SYSCALL_DEFINE3()
830  * file_close_fd - return file associated with fd
831  * @fd: file descriptor to retrieve file for
835  * Returns: The file associated with @fd (NULL if @fd is not open)
837 struct file *file_close_fd(unsigned int fd)  in file_close_fd()
840 	struct file *file;  in file_close_fd()  local
843 	file = file_close_fd_locked(files, fd);  in file_close_fd()
846 	return file;  in file_close_fd()
867 			struct file *file;  in do_close_on_exec()  local
870 			file = fdt->fd[fd];  in do_close_on_exec()
871 			if (!file)  in do_close_on_exec()
876 			filp_close(file, files);  in do_close_on_exec()
885 static struct file *__get_file_rcu(struct file __rcu **f)  in __get_file_rcu()
887 	struct file __rcu *file;  in __get_file_rcu()  local
888 	struct file __rcu *file_reloaded;  in __get_file_rcu()
889 	struct file __rcu *file_reloaded_cmp;  in __get_file_rcu()
891 	file = rcu_dereference_raw(*f);  in __get_file_rcu()
892 	if (!file)  in __get_file_rcu()
895 	if (unlikely(!file_ref_get(&file->f_ref)))  in __get_file_rcu()
913 	 * __rcu protected file pointer so that if that pointer still  in __get_file_rcu()
914 	 * matches the current file, we know we have successfully  in __get_file_rcu()
915 	 * acquired a reference to the right file.  in __get_file_rcu()
917 	 * If the pointers don't match the file has been reallocated by  in __get_file_rcu()
920 	if (file == file_reloaded_cmp)  in __get_file_rcu()
923 	fput(file);  in __get_file_rcu()
928  * get_file_rcu - try go get a reference to a file under rcu
929  * @f: the file to get a reference on
939 struct file *get_file_rcu(struct file __rcu **f)  in get_file_rcu()
942 		struct file __rcu *file;  in get_file_rcu()  local
944 		file = __get_file_rcu(f);  in get_file_rcu()
945 		if (!IS_ERR(file))  in get_file_rcu()
946 			return file;  in get_file_rcu()
952  * get_file_active - try go get a reference to a file
953  * @f: the file to get a reference on
963 struct file *get_file_active(struct file **f)  in get_file_active()
965 	struct file __rcu *file;  in get_file_active()  local
968 	file = __get_file_rcu(f);  in get_file_active()
970 	if (IS_ERR(file))  in get_file_active()
971 		file = NULL;  in get_file_active()
972 	return file;  in get_file_active()
976 static inline struct file *__fget_files_rcu(struct files_struct *files,  in __fget_files_rcu()
980 		struct file *file;  in __fget_files_rcu()  local
982 		struct file __rcu **fdentry;  in __fget_files_rcu()
996 		file = rcu_dereference_raw(*fdentry);  in __fget_files_rcu()
997 		file = (void *)(nospec_mask & (unsigned long)file);  in __fget_files_rcu()
998 		if (unlikely(!file))  in __fget_files_rcu()
1002 		 * Ok, we have a file pointer that was valid at  in __fget_files_rcu()
1012 		if (unlikely(!file_ref_get(&file->f_ref)))  in __fget_files_rcu()
1018 		 *  (a) the file ref already went down to zero and the  in __fget_files_rcu()
1019 		 *      file hasn't been reused yet or the file count  in __fget_files_rcu()
1020 		 *      isn't zero but the file has already been reused.  in __fget_files_rcu()
1022 		 *  (b) the file table entry has changed under us.  in __fget_files_rcu()
1029 		if (unlikely(file != rcu_dereference_raw(*fdentry)) ||  in __fget_files_rcu()
1031 			fput(file);  in __fget_files_rcu()
1036 		 * This isn't the file we're looking for or we're not  in __fget_files_rcu()
1039 		if (unlikely(file->f_mode & mask)) {  in __fget_files_rcu()
1040 			fput(file);  in __fget_files_rcu()
1045 		 * Ok, we have a ref to the file, and checked that it  in __fget_files_rcu()
1048 		return file;  in __fget_files_rcu()
1052 static struct file *__fget_files(struct files_struct *files, unsigned int fd,  in __fget_files()
1055 	struct file *file;  in __fget_files()  local
1058 	file = __fget_files_rcu(files, fd, mask);  in __fget_files()
1061 	return file;  in __fget_files()
1064 static inline struct file *__fget(unsigned int fd, fmode_t mask)  in __fget()
1069 struct file *fget(unsigned int fd)  in fget()
1075 struct file *fget_raw(unsigned int fd)  in fget_raw()
1081 struct file *fget_task(struct task_struct *task, unsigned int fd)  in fget_task()
1083 	struct file *file = NULL;  in fget_task()  local
1087 		file = __fget_files(task->files, fd, 0);  in fget_task()
1090 	return file;  in fget_task()
1093 struct file *fget_task_next(struct task_struct *task, unsigned int *ret_fd)  in fget_task_next()
1098 	struct file *file = NULL;  in fget_task_next()  local
1105 			file = __fget_files_rcu(files, fd, 0);  in fget_task_next()
1106 			if (file)  in fget_task_next()
1113 	return file;  in fget_task_next()
1118  * Lightweight file lookup - no refcnt increment if fd table isn't shared.
1123  *    to userspace (i.e. you cannot remember the returned struct file * after
1125  * 2) You must not call filp_close on the returned struct file * in between
1138  * See also the documentation in rust/kernel/file.rs.
1143 	struct file *file;  in __fget_light()  local
1149 	 * return a file that is concurrently being freed.  in __fget_light()
1155 		file = files_lookup_fd_raw(files, fd);  in __fget_light()
1156 		if (!file || unlikely(file->f_mode & mask))  in __fget_light()
1158 		return BORROWED_FD(file);  in __fget_light()
1160 		file = __fget_files(files, fd, mask);  in __fget_light()
1161 		if (!file)  in __fget_light()
1163 		return CLONED_FD(file);  in __fget_light()
1179  * file is marked for FMODE_ATOMIC_POS, and it can be
1183  * can make a file accessible even if it otherwise would
1187 static inline bool file_needs_f_pos_lock(struct file *file)  in file_needs_f_pos_lock()  argument
1189 	return (file->f_mode & FMODE_ATOMIC_POS) &&  in file_needs_f_pos_lock()
1190 		(file_count(file) > 1 || file->f_op->iterate_shared);  in file_needs_f_pos_lock()
1196 	struct file *file = fd_file(f);  in fdget_pos()  local
1198 	if (file && file_needs_f_pos_lock(file)) {  in fdget_pos()
1200 		mutex_lock(&file->f_pos_lock);  in fdget_pos()
1205 void __f_unlock_pos(struct file *f)  in __f_unlock_pos()
1211  * We only lock f_pos if we have threads or if the file might be
1213  * file count (done either by fdget() or by fork()).
1234 	struct file *file, unsigned fd, unsigned flags)  in do_dup2()  argument
1237 	struct file *tofree;  in do_dup2()
1251 	get_file(file);  in do_dup2()
1252 	rcu_assign_pointer(fdt->fd[fd], file);  in do_dup2()
1266 int replace_fd(unsigned fd, struct file *file, unsigned flags)  in replace_fd()  argument
1271 	if (!file)  in replace_fd()
1281 	return do_dup2(files, file, fd, flags);  in replace_fd()
1289  * receive_fd() - Install received file into file descriptor table
1290  * @file: struct file that was received from another process
1294  * Installs a received file into the file descriptor table, with appropriate
1299  * struct file.
1303 int receive_fd(struct file *file, int __user *ufd, unsigned int o_flags)  in receive_fd()  argument
1308 	error = security_file_receive(file);  in receive_fd()
1324 	fd_install(new_fd, get_file(file));  in receive_fd()
1325 	__receive_sock(file);  in receive_fd()
1330 int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags)  in receive_fd_replace()  argument
1334 	error = security_file_receive(file);  in receive_fd_replace()
1337 	error = replace_fd(new_fd, file, o_flags);  in receive_fd_replace()
1340 	__receive_sock(file);  in receive_fd_replace()
1347 	struct file *file;  in ksys_dup3()  local
1361 	file = files_lookup_fd_locked(files, oldfd);  in ksys_dup3()
1362 	if (unlikely(!file))  in ksys_dup3()
1369 	return do_dup2(files, file, newfd, flags);  in ksys_dup3()
1387 		struct file *f;  in SYSCALL_DEFINE2()
1405 	struct file *file = fget_raw(fildes);  in SYSCALL_DEFINE1()  local
1407 	if (file) {  in SYSCALL_DEFINE1()
1410 			fd_install(ret, file);  in SYSCALL_DEFINE1()
1412 			fput(file);  in SYSCALL_DEFINE1()
1417 int f_dupfd(unsigned int from, struct file *file, unsigned flags)  in f_dupfd()  argument
1425 		get_file(file);  in f_dupfd()
1426 		fd_install(err, file);  in f_dupfd()
1432 		int (*f)(const void *, struct file *, unsigned),  in iterate_fd()  argument
1441 		struct file *file;  in iterate_fd()  local
1442 		file = rcu_dereference_check_fdtable(files, fdt->fd[n]);  in iterate_fd()
1443 		if (!file)  in iterate_fd()
1445 		res = f(p, file, n);  in iterate_fd()