/* *  linux/fs/readdir.c * *  Copyright (C) 1995  Linus Torvalds */ #include <linux/stddef.h>#include <linux/kernel.h>#include <linux/export.h>#include <linux/time.h>#include <linux/mm.h>#include <linux/errno.h>#include <linux/stat.h>#include <linux/file.h>#include <linux/fs.h>#include <linux/fsnotify.h>#include <linux/dirent.h>#include <linux/security.h>#include <linux/syscalls.h>#include <linux/unistd.h>#include <linux/compat.h> #include <linux/uaccess.h> int iterate_dir(struct file *file, struct dir_context *ctx){	struct inode *inode = file_inode(file);	bool shared = false;	int res = -ENOTDIR;	if (file->f_op->iterate_shared)		shared = true;	else if (!file->f_op->iterate)		goto out; 	res = security_file_permission(file, MAY_READ);	if (res)		goto out; 	if (shared) {		inode_lock_shared(inode);	} else {		res = down_write_killable(&inode->i_rwsem);		if (res)			goto out;	} 	res = -ENOENT;	if (!IS_DEADDIR(inode)) {		ctx->pos = file->f_pos;		if (shared)			res = file->f_op->iterate_shared(file, ctx);		else			res = file->f_op->iterate(file, ctx);		file->f_pos = ctx->pos;		fsnotify_access(file);		file_accessed(file);	}	if (shared)		inode_unlock_shared(inode);	else		inode_unlock(inode);out:	return res;}EXPORT_SYMBOL(iterate_dir); /* * Traditional linux readdir() handling.. * * "count=1" is a special case, meaning that the buffer is one * dirent-structure in size and that the code can't handle more * anyway. Thus the special "fillonedir()" function for that * case (the low-level handlers don't need to care about this). */ #ifdef __ARCH_WANT_OLD_READDIR struct old_linux_dirent {	unsigned long	d_ino;	unsigned long	d_offset;	unsigned short	d_namlen;	char		d_name[1];}; struct readdir_callback {	struct dir_context ctx;	struct old_linux_dirent __user * dirent;	int result;}; static int fillonedir(struct dir_context *ctx, const char *name, int namlen,		      loff_t offset, u64 ino, unsigned int d_type){	struct readdir_callback *buf =		container_of(ctx, struct readdir_callback, ctx);	struct old_linux_dirent __user * dirent;	unsigned long d_ino; 	if (buf->result)		return -EINVAL;	d_ino = ino;	if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {		buf->result = -EOVERFLOW;		return -EOVERFLOW;	}	buf->result++;	dirent = buf->dirent;	if (!access_ok(VERIFY_WRITE, dirent,			(unsigned long)(dirent->d_name + namlen + 1) -				(unsigned long)dirent))		goto efault;	if (	__put_user(d_ino, &dirent->d_ino) ||		__put_user(offset, &dirent->d_offset) ||		__put_user(namlen, &dirent->d_namlen) ||		__copy_to_user(dirent->d_name, name, namlen) ||		__put_user(0, dirent->d_name + namlen))		goto efault;	return 0;efault:	buf->result = -EFAULT;	return -EFAULT;} SYSCALL_DEFINE3(old_readdir, unsigned int, fd,		struct old_linux_dirent __user *, dirent, unsigned int, count){	int error;	struct fd f = fdget_pos(fd);	struct readdir_callback buf = {		.ctx.actor = fillonedir,		.dirent = dirent	}; 	if (!f.file)		return -EBADF; 	error = iterate_dir(f.file, &buf.ctx);	if (buf.result)		error = buf.result; 	fdput_pos(f);	return error;} #endif /* __ARCH_WANT_OLD_READDIR */ /* * New, all-improved, singing, dancing, iBCS2-compliant getdents() * interface.  */struct linux_dirent {	unsigned long	d_ino;	unsigned long	d_off;	unsigned short	d_reclen;	char		d_name[1];}; struct getdents_callback {	struct dir_context ctx;	struct linux_dirent __user * current_dir;	struct linux_dirent __user * previous;	int count;	int error;}; static int filldir(struct dir_context *ctx, const char *name, int namlen,		   loff_t offset, u64 ino, unsigned int d_type){	struct linux_dirent __user * dirent;	struct getdents_callback *buf =		container_of(ctx, struct getdents_callback, ctx);	unsigned long d_ino;	int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,		sizeof(long)); 	buf->error = -EINVAL;	/* only used if we fail.. */	if (reclen > buf->count)		return -EINVAL;	d_ino = ino;	if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {		buf->error = -EOVERFLOW;		return -EOVERFLOW;	}	dirent = buf->previous;	if (dirent) {		if (signal_pending(current))			return -EINTR;		if (__put_user(offset, &dirent->d_off))			goto efault;	}	dirent = buf->current_dir;	if (__put_user(d_ino, &dirent->d_ino))		goto efault;	if (__put_user(reclen, &dirent->d_reclen))		goto efault;	if (copy_to_user(dirent->d_name, name, namlen))		goto efault;	if (__put_user(0, dirent->d_name + namlen))		goto efault;	if (__put_user(d_type, (char __user *) dirent + reclen - 1))		goto efault;	buf->previous = dirent;	dirent = (void __user *)dirent + reclen;	buf->current_dir = dirent;	buf->count -= reclen;	return 0;efault:	buf->error = -EFAULT;	return -EFAULT;} SYSCALL_DEFINE3(getdents, unsigned int, fd,		struct linux_dirent __user *, dirent, unsigned int, count){	struct fd f;	struct linux_dirent __user * lastdirent;	struct getdents_callback buf = {		.ctx.actor = filldir,		.count = count,		.current_dir = dirent	};	int error; 	if (!access_ok(VERIFY_WRITE, dirent, count))		return -EFAULT; 	f = fdget_pos(fd);	if (!f.file)		return -EBADF; 	error = iterate_dir(f.file, &buf.ctx);	if (error >= 0)		error = buf.error;	lastdirent = buf.previous;	if (lastdirent) {		if (put_user(buf.ctx.pos, &lastdirent->d_off))			error = -EFAULT;		else			error = count - buf.count;	}	fdput_pos(f);	return error;} struct getdents_callback64 {	struct dir_context ctx;	struct linux_dirent64 __user * current_dir;	struct linux_dirent64 __user * previous;	int count;	int error;}; static int filldir64(struct dir_context *ctx, const char *name, int namlen,		     loff_t offset, u64 ino, unsigned int d_type){	struct linux_dirent64 __user *dirent;	struct getdents_callback64 *buf =		container_of(ctx, struct getdents_callback64, ctx);	int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,		sizeof(u64)); 	buf->error = -EINVAL;	/* only used if we fail.. */	if (reclen > buf->count)		return -EINVAL;	dirent = buf->previous;	if (dirent) {		if (signal_pending(current))			return -EINTR;		if (__put_user(offset, &dirent->d_off))			goto efault;	}	dirent = buf->current_dir;	if (__put_user(ino, &dirent->d_ino))		goto efault;	if (__put_user(0, &dirent->d_off))		goto efault;	if (__put_user(reclen, &dirent->d_reclen))		goto efault;	if (__put_user(d_type, &dirent->d_type))		goto efault;	if (copy_to_user(dirent->d_name, name, namlen))		goto efault;	if (__put_user(0, dirent->d_name + namlen))		goto efault;	buf->previous = dirent;	dirent = (void __user *)dirent + reclen;	buf->current_dir = dirent;	buf->count -= reclen;	return 0;efault:	buf->error = -EFAULT;	return -EFAULT;} SYSCALL_DEFINE3(getdents64, unsigned int, fd,		struct linux_dirent64 __user *, dirent, unsigned int, count){	struct fd f;	struct linux_dirent64 __user * lastdirent;	struct getdents_callback64 buf = {		.ctx.actor = filldir64,		.count = count,		.current_dir = dirent	};	int error; 	if (!access_ok(VERIFY_WRITE, dirent, count))		return -EFAULT; 	f = fdget_pos(fd);	if (!f.file)		return -EBADF; 	error = iterate_dir(f.file, &buf.ctx);	if (error >= 0)		error = buf.error;	lastdirent = buf.previous;	if (lastdirent) {		typeof(lastdirent->d_off) d_off = buf.ctx.pos;		if (__put_user(d_off, &lastdirent->d_off))			error = -EFAULT;		else			error = count - buf.count;	}	fdput_pos(f);	return error;} #ifdef CONFIG_COMPATstruct compat_old_linux_dirent {	compat_ulong_t	d_ino;	compat_ulong_t	d_offset;	unsigned short	d_namlen;	char		d_name[1];}; struct compat_readdir_callback {	struct dir_context ctx;	struct compat_old_linux_dirent __user *dirent;	int result;}; static int compat_fillonedir(struct dir_context *ctx, const char *name,			     int namlen, loff_t offset, u64 ino,			     unsigned int d_type){	struct compat_readdir_callback *buf =		container_of(ctx, struct compat_readdir_callback, ctx);	struct compat_old_linux_dirent __user *dirent;	compat_ulong_t d_ino; 	if (buf->result)		return -EINVAL;	d_ino = ino;	if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {		buf->result = -EOVERFLOW;		return -EOVERFLOW;	}	buf->result++;	dirent = buf->dirent;	if (!access_ok(VERIFY_WRITE, dirent,			(unsigned long)(dirent->d_name + namlen + 1) -				(unsigned long)dirent))		goto efault;	if (	__put_user(d_ino, &dirent->d_ino) ||		__put_user(offset, &dirent->d_offset) ||		__put_user(namlen, &dirent->d_namlen) ||		__copy_to_user(dirent->d_name, name, namlen) ||		__put_user(0, dirent->d_name + namlen))		goto efault;	return 0;efault:	buf->result = -EFAULT;	return -EFAULT;} COMPAT_SYSCALL_DEFINE3(old_readdir, unsigned int, fd,		struct compat_old_linux_dirent __user *, dirent, unsigned int, count){	int error;	struct fd f = fdget_pos(fd);	struct compat_readdir_callback buf = {		.ctx.actor = compat_fillonedir,		.dirent = dirent	}; 	if (!f.file)		return -EBADF; 	error = iterate_dir(f.file, &buf.ctx);	if (buf.result)		error = buf.result; 	fdput_pos(f);	return error;} struct compat_linux_dirent {	compat_ulong_t	d_ino;	compat_ulong_t	d_off;	unsigned short	d_reclen;	char		d_name[1];}; struct compat_getdents_callback {	struct dir_context ctx;	struct compat_linux_dirent __user *current_dir;	struct compat_linux_dirent __user *previous;	int count;	int error;}; static int compat_filldir(struct dir_context *ctx, const char *name, int namlen,		loff_t offset, u64 ino, unsigned int d_type){	struct compat_linux_dirent __user * dirent;	struct compat_getdents_callback *buf =		container_of(ctx, struct compat_getdents_callback, ctx);	compat_ulong_t d_ino;	int reclen = ALIGN(offsetof(struct compat_linux_dirent, d_name) +		namlen + 2, sizeof(compat_long_t)); 	buf->error = -EINVAL;	/* only used if we fail.. */	if (reclen > buf->count)		return -EINVAL;	d_ino = ino;	if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {		buf->error = -EOVERFLOW;		return -EOVERFLOW;	}	dirent = buf->previous;	if (dirent) {		if (signal_pending(current))			return -EINTR;		if (__put_user(offset, &dirent->d_off))			goto efault;	}	dirent = buf->current_dir;	if (__put_user(d_ino, &dirent->d_ino))		goto efault;	if (__put_user(reclen, &dirent->d_reclen))		goto efault;	if (copy_to_user(dirent->d_name, name, namlen))		goto efault;	if (__put_user(0, dirent->d_name + namlen))		goto efault;	if (__put_user(d_type, (char  __user *) dirent + reclen - 1))		goto efault;	buf->previous = dirent;	dirent = (void __user *)dirent + reclen;	buf->current_dir = dirent;	buf->count -= reclen;	return 0;efault:	buf->error = -EFAULT;	return -EFAULT;} COMPAT_SYSCALL_DEFINE3(getdents, unsigned int, fd,		struct compat_linux_dirent __user *, dirent, unsigned int, count){	struct fd f;	struct compat_linux_dirent __user * lastdirent;	struct compat_getdents_callback buf = {		.ctx.actor = compat_filldir,		.current_dir = dirent,		.count = count	};	int error; 	if (!access_ok(VERIFY_WRITE, dirent, count))		return -EFAULT; 	f = fdget_pos(fd);	if (!f.file)		return -EBADF; 	error = iterate_dir(f.file, &buf.ctx);	if (error >= 0)		error = buf.error;	lastdirent = buf.previous;	if (lastdirent) {		if (put_user(buf.ctx.pos, &lastdirent->d_off))			error = -EFAULT;		else			error = count - buf.count;	}	fdput_pos(f);	return error;}#endif