3  *  linux/fs/file.c
17 #include <linux/file.h>
52  * space if any.  This does not copy the file pointers.  Called with the files
69  * Copy all file descriptors from the old table to the new, expanded table and
78 	cpy = ofdt->max_fds * sizeof(struct file *);  in copy_fdtable()
79 	set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *);  in copy_fdtable()
113 	nr /= (1024 / sizeof(struct file *));  in alloc_fdtable()
115 	nr *= (1024 / sizeof(struct file *));  in alloc_fdtable()
132 	data = kvmalloc_array(nr, sizeof(struct file *), GFP_KERNEL_ACCOUNT);  in alloc_fdtable()
159  * Expand the file descriptor table.
204  * This function will expand the file structures, if the requested size exceeds
306 	struct file **old_fds, **new_fds;  in dup_fd()
370 		struct file *f = *old_fds++;  in dup_fd()
387 	memset(new_fds, 0, (new_fdt->max_fds - open_files) * sizeof(struct file *));  in dup_fd()
416 				struct file * file = xchg(&fdt->fd[i], NULL);  in close_files()  local
417 				if (file) {  in close_files()
418 					filp_close(file, files);  in close_files()
483  * allocate a file descriptor, mark it busy.
573  * Install a file pointer in the fd array.
576  * setting the open_fds bitmap and installing the file in the file
578  * installing a file in the array before us.  We need to detect this and
579  * fput() the struct file we are about to overwrite in this case.
584  * This consumes the "file" refcount, so callers should treat it
585  * as if they had called fput(file).
588 void fd_install(unsigned int fd, struct file *file)  in fd_install()  argument
593 	if (WARN_ON_ONCE(unlikely(file->f_mode & FMODE_BACKING)))  in fd_install()
603 		rcu_assign_pointer(fdt->fd[fd], file);  in fd_install()
611 	rcu_assign_pointer(fdt->fd[fd], file);  in fd_install()
618  * file_close_fd_locked - return file associated with fd
619  * @files: file struct to retrieve file from
620  * @fd: file descriptor to retrieve file for
626  * Returns: The file associated with @fd (NULL if @fd is not open)
628 struct file *file_close_fd_locked(struct files_struct *files, unsigned fd)  in file_close_fd_locked()
631 	struct file *file;  in file_close_fd_locked()  local
639 	file = fdt->fd[fd];  in file_close_fd_locked()
640 	if (file) {  in file_close_fd_locked()
644 	return file;  in file_close_fd_locked()
650 	struct file *file;  in close_fd()  local
653 	file = file_close_fd_locked(files, fd);  in close_fd()
655 	if (!file)  in close_fd()
658 	return filp_close(file, files);  in close_fd()
664  * @fdt: File descriptor table.
692 	struct file *file;  in __range_close()  local
700 		file = file_close_fd_locked(files, fd);  in __range_close()
701 		if (file) {  in __range_close()
703 			filp_close(file, files);  in __range_close()
716  * __close_range() - Close all file descriptors in a given range.
718  * @fd:     starting file descriptor to close
719  * @max_fd: last file descriptor to close
722  * This closes a range of file descriptors. All file descriptors
741 		 * copy all of the file descriptors since they still want to  in __close_range()
751 		 * We used to share our file descriptor table, and have now  in __close_range()
765 		 * the new file descriptor table and drop the old one.  in __close_range()
777  * file_close_fd - return file associated with fd
778  * @fd: file descriptor to retrieve file for
782  * Returns: The file associated with @fd (NULL if @fd is not open)
784 struct file *file_close_fd(unsigned int fd)  in file_close_fd()
787 	struct file *file;  in file_close_fd()  local
790 	file = file_close_fd_locked(files, fd);  in file_close_fd()
793 	return file;  in file_close_fd()
814 			struct file *file;  in do_close_on_exec()  local
817 			file = fdt->fd[fd];  in do_close_on_exec()
818 			if (!file)  in do_close_on_exec()
823 			filp_close(file, files);  in do_close_on_exec()
832 static struct file *__get_file_rcu(struct file __rcu **f)  in __get_file_rcu()
834 	struct file __rcu *file;  in __get_file_rcu()  local
835 	struct file __rcu *file_reloaded;  in __get_file_rcu()
836 	struct file __rcu *file_reloaded_cmp;  in __get_file_rcu()
838 	file = rcu_dereference_raw(*f);  in __get_file_rcu()
839 	if (!file)  in __get_file_rcu()
842 	if (unlikely(!atomic_long_inc_not_zero(&file->f_count)))  in __get_file_rcu()
860 	 * __rcu protected file pointer so that if that pointer still  in __get_file_rcu()
861 	 * matches the current file, we know we have successfully  in __get_file_rcu()
862 	 * acquired a reference to the right file.  in __get_file_rcu()
864 	 * If the pointers don't match the file has been reallocated by  in __get_file_rcu()
867 	if (file == file_reloaded_cmp)  in __get_file_rcu()
870 	fput(file);  in __get_file_rcu()
875  * get_file_rcu - try go get a reference to a file under rcu
876  * @f: the file to get a reference on
886 struct file *get_file_rcu(struct file __rcu **f)  in get_file_rcu()
889 		struct file __rcu *file;  in get_file_rcu()  local
891 		file = __get_file_rcu(f);  in get_file_rcu()
892 		if (!IS_ERR(file))  in get_file_rcu()
893 			return file;  in get_file_rcu()
899  * get_file_active - try go get a reference to a file
900  * @f: the file to get a reference on
910 struct file *get_file_active(struct file **f)  in get_file_active()
912 	struct file __rcu *file;  in get_file_active()  local
915 	file = __get_file_rcu(f);  in get_file_active()
917 	if (IS_ERR(file))  in get_file_active()
918 		file = NULL;  in get_file_active()
919 	return file;  in get_file_active()
923 static inline struct file *__fget_files_rcu(struct files_struct *files,  in __fget_files_rcu()
927 		struct file *file;  in __fget_files_rcu()  local
929 		struct file __rcu **fdentry;  in __fget_files_rcu()
943 		file = rcu_dereference_raw(*fdentry);  in __fget_files_rcu()
944 		file = (void *)(nospec_mask & (unsigned long)file);  in __fget_files_rcu()
945 		if (unlikely(!file))  in __fget_files_rcu()
949 		 * Ok, we have a file pointer that was valid at  in __fget_files_rcu()
959 		if (unlikely(!atomic_long_inc_not_zero(&file->f_count)))  in __fget_files_rcu()
965 		 *  (a) the file ref already went down to zero and the  in __fget_files_rcu()
966 		 *      file hasn't been reused yet or the file count  in __fget_files_rcu()
967 		 *      isn't zero but the file has already been reused.  in __fget_files_rcu()
969 		 *  (b) the file table entry has changed under us.  in __fget_files_rcu()
976 		if (unlikely(file != rcu_dereference_raw(*fdentry)) ||  in __fget_files_rcu()
978 			fput(file);  in __fget_files_rcu()
983 		 * This isn't the file we're looking for or we're not  in __fget_files_rcu()
986 		if (unlikely(file->f_mode & mask)) {  in __fget_files_rcu()
987 			fput(file);  in __fget_files_rcu()
992 		 * Ok, we have a ref to the file, and checked that it  in __fget_files_rcu()
995 		return file;  in __fget_files_rcu()
999 static struct file *__fget_files(struct files_struct *files, unsigned int fd,  in __fget_files()
1002 	struct file *file;  in __fget_files()  local
1005 	file = __fget_files_rcu(files, fd, mask);  in __fget_files()
1008 	return file;  in __fget_files()
1011 static inline struct file *__fget(unsigned int fd, fmode_t mask)  in __fget()
1016 struct file *fget(unsigned int fd)  in fget()
1022 struct file *fget_raw(unsigned int fd)  in fget_raw()
1028 struct file *fget_task(struct task_struct *task, unsigned int fd)  in fget_task()
1030 	struct file *file = NULL;  in fget_task()  local
1034 		file = __fget_files(task->files, fd, 0);  in fget_task()
1037 	return file;  in fget_task()
1040 struct file *lookup_fdget_rcu(unsigned int fd)  in lookup_fdget_rcu()
1047 struct file *task_lookup_fdget_rcu(struct task_struct *task, unsigned int fd)  in task_lookup_fdget_rcu()
1051 	struct file *file = NULL;  in task_lookup_fdget_rcu()  local
1056 		file = __fget_files_rcu(files, fd, 0);  in task_lookup_fdget_rcu()
1059 	return file;  in task_lookup_fdget_rcu()
1062 struct file *task_lookup_next_fdget_rcu(struct task_struct *task, unsigned int *ret_fd)  in task_lookup_next_fdget_rcu()
1067 	struct file *file = NULL;  in task_lookup_next_fdget_rcu()  local
1073 			file = __fget_files_rcu(files, fd, 0);  in task_lookup_next_fdget_rcu()
1074 			if (file)  in task_lookup_next_fdget_rcu()
1080 	return file;  in task_lookup_next_fdget_rcu()
1085  * Lightweight file lookup - no refcnt increment if fd table isn't shared.
1090  *    to userspace (i.e. you cannot remember the returned struct file * after
1092  * 2) You must not call filp_close on the returned struct file * in between
1103 	struct file *file;  in __fget_light()  local
1109 	 * return a file that is concurrently being freed.  in __fget_light()
1115 		file = files_lookup_fd_raw(files, fd);  in __fget_light()
1116 		if (!file || unlikely(file->f_mode & mask))  in __fget_light()
1118 		return BORROWED_FD(file);  in __fget_light()
1120 		file = __fget_files(files, fd, mask);  in __fget_light()
1121 		if (!file)  in __fget_light()
1123 		return CLONED_FD(file);  in __fget_light()
1139  * file is marked for FMODE_ATOMIC_POS, and it can be
1143  * can make a file accessible even if it otherwise would
1147 static inline bool file_needs_f_pos_lock(struct file *file)  in file_needs_f_pos_lock()  argument
1149 	return (file->f_mode & FMODE_ATOMIC_POS) &&  in file_needs_f_pos_lock()
1150 		(file_count(file) > 1 || file->f_op->iterate_shared);  in file_needs_f_pos_lock()
1156 	struct file *file = fd_file(f);  in fdget_pos()  local
1158 	if (file && file_needs_f_pos_lock(file)) {  in fdget_pos()
1160 		mutex_lock(&file->f_pos_lock);  in fdget_pos()
1165 void __f_unlock_pos(struct file *f)  in __f_unlock_pos()
1171  * We only lock f_pos if we have threads or if the file might be
1173  * file count (done either by fdget() or by fork()).
1199 	struct file *file, unsigned fd, unsigned flags)  in do_dup2()  argument
1202 	struct file *tofree;  in do_dup2()
1209 	 * file immediately after grabbing descriptor, mark it larval if  in do_dup2()
1224 	get_file(file);  in do_dup2()
1225 	rcu_assign_pointer(fdt->fd[fd], file);  in do_dup2()
1243 int replace_fd(unsigned fd, struct file *file, unsigned flags)  in replace_fd()  argument
1248 	if (!file)  in replace_fd()
1258 	return do_dup2(files, file, fd, flags);  in replace_fd()
1266  * receive_fd() - Install received file into file descriptor table
1267  * @file: struct file that was received from another process
1271  * Installs a received file into the file descriptor table, with appropriate
1276  * struct file.
1280 int receive_fd(struct file *file, int __user *ufd, unsigned int o_flags)  in receive_fd()  argument
1285 	error = security_file_receive(file);  in receive_fd()
1301 	fd_install(new_fd, get_file(file));  in receive_fd()
1302 	__receive_sock(file);  in receive_fd()
1307 int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags)  in receive_fd_replace()  argument
1311 	error = security_file_receive(file);  in receive_fd_replace()
1314 	error = replace_fd(new_fd, file, o_flags);  in receive_fd_replace()
1317 	__receive_sock(file);  in receive_fd_replace()
1324 	struct file *file;  in ksys_dup3()  local
1338 	file = files_lookup_fd_locked(files, oldfd);  in ksys_dup3()
1339 	if (unlikely(!file))  in ksys_dup3()
1346 	return do_dup2(files, file, newfd, flags);  in ksys_dup3()
1364 		struct file *f;  in SYSCALL_DEFINE2()
1382 	struct file *file = fget_raw(fildes);  in SYSCALL_DEFINE1()  local
1384 	if (file) {  in SYSCALL_DEFINE1()
1387 			fd_install(ret, file);  in SYSCALL_DEFINE1()
1389 			fput(file);  in SYSCALL_DEFINE1()
1394 int f_dupfd(unsigned int from, struct file *file, unsigned flags)  in f_dupfd()  argument
1402 		get_file(file);  in f_dupfd()
1403 		fd_install(err, file);  in f_dupfd()
1409 		int (*f)(const void *, struct file *, unsigned),  in iterate_fd()  argument
1418 		struct file *file;  in iterate_fd()  local
1419 		file = rcu_dereference_check_fdtable(files, fdt->fd[n]);  in iterate_fd()
1420 		if (!file)  in iterate_fd()
1422 		res = f(p, file, n);  in iterate_fd()