linux/fs/xfs/xfs_handle.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All rights reserved.
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_shared.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_inode.h"
#include "xfs_error.h"
#include "xfs_trace.h"
#include "xfs_trans.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_attr.h"
#include "xfs_ioctl.h"
#include "xfs_parent.h"
#include "xfs_da_btree.h"
#include "xfs_handle.h"
#include "xfs_health.h"
#include "xfs_icache.h"
#include "xfs_export.h"
#include "xfs_xattr.h"
#include "xfs_acl.h"

#include <linux/namei.h>

/*
 * xfs_find_handle maps from userspace xfs_fsop_handlereq structure to
 * a file or fs handle.
 *
 * XFS_IOC_PATH_TO_FSHANDLE
 *    returns fs handle for a mount point or path within that mount point
 * XFS_IOC_FD_TO_HANDLE
 *    returns full handle for a FD opened in user space
 * XFS_IOC_PATH_TO_HANDLE
 *    returns full handle for a path
 */
int
xfs_find_handle(
	unsigned int		cmd,
	xfs_fsop_handlereq_t	*hreq)
{
	int			hsize;
	xfs_handle_t		handle;
	struct inode		*inode;
	struct fd		f = {NULL};
	struct path		path;
	int			error;
	struct xfs_inode	*ip;

	if (cmd == XFS_IOC_FD_TO_HANDLE) {
		f = fdget(hreq->fd);
		if (!f.file)
			return -EBADF;
		inode = file_inode(f.file);
	} else {
		error = user_path_at(AT_FDCWD, hreq->path, 0, &path);
		if (error)
			return error;
		inode = d_inode(path.dentry);
	}
	ip = XFS_I(inode);

	/*
	 * We can only generate handles for inodes residing on a XFS filesystem,
	 * and only for regular files, directories or symbolic links.
	 */
	error = -EINVAL;
	if (inode->i_sb->s_magic != XFS_SB_MAGIC)
		goto out_put;

	error = -EBADF;
	if (!S_ISREG(inode->i_mode) &&
	    !S_ISDIR(inode->i_mode) &&
	    !S_ISLNK(inode->i_mode))
		goto out_put;


	memcpy(&handle.ha_fsid, ip->i_mount->m_fixedfsid, sizeof(xfs_fsid_t));

	if (cmd == XFS_IOC_PATH_TO_FSHANDLE) {
		/*
		 * This handle only contains an fsid, zero the rest.
		 */
		memset(&handle.ha_fid, 0, sizeof(handle.ha_fid));
		hsize = sizeof(xfs_fsid_t);
	} else {
		handle.ha_fid.fid_len = sizeof(xfs_fid_t) -
					sizeof(handle.ha_fid.fid_len);
		handle.ha_fid.fid_pad = 0;
		handle.ha_fid.fid_gen = inode->i_generation;
		handle.ha_fid.fid_ino = ip->i_ino;
		hsize = sizeof(xfs_handle_t);
	}

	error = -EFAULT;
	if (copy_to_user(hreq->ohandle, &handle, hsize) ||
	    copy_to_user(hreq->ohandlen, &hsize, sizeof(__s32)))
		goto out_put;

	error = 0;

 out_put:
	if (cmd == XFS_IOC_FD_TO_HANDLE)
		fdput(f);
	else
		path_put(&path);
	return error;
}

/*
 * No need to do permission checks on the various pathname components
 * as the handle operations are privileged.
 */
STATIC int
xfs_handle_acceptable(
	void			*context,
	struct dentry		*dentry)
{
	return 1;
}

/*
 * Convert userspace handle data into a dentry.
 */
struct dentry *
xfs_handle_to_dentry(
	struct file		*parfilp,
	void __user		*uhandle,
	u32			hlen)
{
	xfs_handle_t		handle;
	struct xfs_fid64	fid;

	/*
	 * Only allow handle opens under a directory.
	 */
	if (!S_ISDIR(file_inode(parfilp)->i_mode))
		return ERR_PTR(-ENOTDIR);

	if (hlen != sizeof(xfs_handle_t))
		return ERR_PTR(-EINVAL);
	if (copy_from_user(&handle, uhandle, hlen))
		return ERR_PTR(-EFAULT);
	if (handle.ha_fid.fid_len !=
	    sizeof(handle.ha_fid) - sizeof(handle.ha_fid.fid_len))
		return ERR_PTR(-EINVAL);

	memset(&fid, 0, sizeof(struct fid));
	fid.ino = handle.ha_fid.fid_ino;
	fid.gen = handle.ha_fid.fid_gen;

	return exportfs_decode_fh(parfilp->f_path.mnt, (struct fid *)&fid, 3,
			FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG,
			xfs_handle_acceptable, NULL);
}

STATIC struct dentry *
xfs_handlereq_to_dentry(
	struct file		*parfilp,
	xfs_fsop_handlereq_t	*hreq)
{
	return xfs_handle_to_dentry(parfilp, hreq->ihandle, hreq->ihandlen);
}

int
xfs_open_by_handle(
	struct file		*parfilp,
	xfs_fsop_handlereq_t	*hreq)
{
	const struct cred	*cred = current_cred();
	int			error;
	int			fd;
	int			permflag;
	struct file		*filp;
	struct inode		*inode;
	struct dentry		*dentry;
	fmode_t			fmode;
	struct path		path;

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	dentry = xfs_handlereq_to_dentry(parfilp, hreq);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);
	inode = d_inode(dentry);

	/* Restrict xfs_open_by_handle to directories & regular files. */
	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))) {
		error = -EPERM;
		goto out_dput;
	}

#if BITS_PER_LONG != 32
	hreq->oflags |= O_LARGEFILE;
#endif

	permflag = hreq->oflags;
	fmode = OPEN_FMODE(permflag);
	if ((!(permflag & O_APPEND) || (permflag & O_TRUNC)) &&
	    (fmode & FMODE_WRITE) && IS_APPEND(inode)) {
		error = -EPERM;
		goto out_dput;
	}

	if ((fmode & FMODE_WRITE) && IS_IMMUTABLE(inode)) {
		error = -EPERM;
		goto out_dput;
	}

	/* Can't write directories. */
	if (S_ISDIR(inode->i_mode) && (fmode & FMODE_WRITE)) {
		error = -EISDIR;
		goto out_dput;
	}

	fd = get_unused_fd_flags(0);
	if (fd < 0) {
		error = fd;
		goto out_dput;
	}

	path.mnt = parfilp->f_path.mnt;
	path.dentry = dentry;
	filp = dentry_open(&path, hreq->oflags, cred);
	dput(dentry);
	if (IS_ERR(filp)) {
		put_unused_fd(fd);
		return PTR_ERR(filp);
	}

	if (S_ISREG(inode->i_mode)) {
		filp->f_flags |= O_NOATIME;
		filp->f_mode |= FMODE_NOCMTIME;
	}

	fd_install(fd, filp);
	return fd;

 out_dput:
	dput(dentry);
	return error;
}

int
xfs_readlink_by_handle(
	struct file		*parfilp,
	xfs_fsop_handlereq_t	*hreq)
{
	struct dentry		*dentry;
	__u32			olen;
	int			error;

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	dentry = xfs_handlereq_to_dentry(parfilp, hreq);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);

	/* Restrict this handle operation to symlinks only. */
	if (!d_is_symlink(dentry)) {
		error = -EINVAL;
		goto out_dput;
	}

	if (copy_from_user(&olen, hreq->ohandlen, sizeof(__u32))) {
		error = -EFAULT;
		goto out_dput;
	}

	error = vfs_readlink(dentry, hreq->ohandle, olen);

 out_dput:
	dput(dentry);
	return error;
}

/*
 * Format an attribute and copy it out to the user's buffer.
 * Take care to check values and protect against them changing later,
 * we may be reading them directly out of a user buffer.
 */
static void
xfs_ioc_attr_put_listent(
	struct xfs_attr_list_context *context,
	int			flags,
	unsigned char		*name,
	int			namelen,
	void			*value,
	int			valuelen)
{
	struct xfs_attrlist	*alist = context->buffer;
	struct xfs_attrlist_ent	*aep;
	int			arraytop;

	ASSERT(!context->seen_enough);
	ASSERT(context->count >= 0);
	ASSERT(context->count < (ATTR_MAX_VALUELEN/8));
	ASSERT(context->firstu >= sizeof(*alist));
	ASSERT(context->firstu <= context->bufsize);

	/*
	 * Only list entries in the right namespace.
	 */
	if (context->attr_filter != (flags & XFS_ATTR_NSP_ONDISK_MASK))
		return;

	arraytop = sizeof(*alist) +
			context->count * sizeof(alist->al_offset[0]);

	/* decrement by the actual bytes used by the attr */
	context->firstu -= round_up(offsetof(struct xfs_attrlist_ent, a_name) +
			namelen + 1, sizeof(uint32_t));
	if (context->firstu < arraytop) {
		trace_xfs_attr_list_full(context);
		alist->al_more = 1;
		context->seen_enough = 1;
		return;
	}

	aep = context->buffer + context->firstu;
	aep->a_valuelen = valuelen;
	memcpy(aep->a_name, name, namelen);
	aep->a_name[namelen] = 0;
	alist->al_offset[context->count++] = context->firstu;
	alist->al_count = context->count;
	trace_xfs_attr_list_add(context);
}

static unsigned int
xfs_attr_filter(
	u32			ioc_flags)
{
	if (ioc_flags & XFS_IOC_ATTR_ROOT)
		return XFS_ATTR_ROOT;
	if (ioc_flags & XFS_IOC_ATTR_SECURE)
		return XFS_ATTR_SECURE;
	return 0;
}

static inline enum xfs_attr_update
xfs_xattr_flags(
	u32			ioc_flags,
	void			*value)
{
	if (!value)
		return XFS_ATTRUPDATE_REMOVE;
	if (ioc_flags & XFS_IOC_ATTR_CREATE)
		return XFS_ATTRUPDATE_CREATE;
	if (ioc_flags & XFS_IOC_ATTR_REPLACE)
		return XFS_ATTRUPDATE_REPLACE;
	return XFS_ATTRUPDATE_UPSERT;
}

int
xfs_ioc_attr_list(
	struct xfs_inode		*dp,
	void __user			*ubuf,
	size_t				bufsize,
	int				flags,
	struct xfs_attrlist_cursor __user *ucursor)
{
	struct xfs_attr_list_context	context = { };
	struct xfs_attrlist		*alist;
	void				*buffer;
	int				error;

	if (bufsize < sizeof(struct xfs_attrlist) ||
	    bufsize > XFS_XATTR_LIST_MAX)
		return -EINVAL;

	/*
	 * Reject flags, only allow namespaces.
	 */
	if (flags & ~(XFS_IOC_ATTR_ROOT | XFS_IOC_ATTR_SECURE))
		return -EINVAL;
	if (flags == (XFS_IOC_ATTR_ROOT | XFS_IOC_ATTR_SECURE))
		return -EINVAL;

	/*
	 * Validate the cursor.
	 */
	if (copy_from_user(&context.cursor, ucursor, sizeof(context.cursor)))
		return -EFAULT;
	if (context.cursor.pad1 || context.cursor.pad2)
		return -EINVAL;
	if (!context.cursor.initted &&
	    (context.cursor.hashval || context.cursor.blkno ||
	     context.cursor.offset))
		return -EINVAL;

	buffer = kvzalloc(bufsize, GFP_KERNEL);
	if (!buffer)
		return -ENOMEM;

	/*
	 * Initialize the output buffer.
	 */
	context.dp = dp;
	context.resynch = 1;
	context.attr_filter = xfs_attr_filter(flags);
	context.buffer = buffer;
	context.bufsize = round_down(bufsize, sizeof(uint32_t));
	context.firstu = context.bufsize;
	context.put_listent = xfs_ioc_attr_put_listent;

	alist = context.buffer;
	alist->al_count = 0;
	alist->al_more = 0;
	alist->al_offset[0] = context.bufsize;

	error = xfs_attr_list(&context);
	if (error)
		goto out_free;

	if (copy_to_user(ubuf, buffer, bufsize) ||
	    copy_to_user(ucursor, &context.cursor, sizeof(context.cursor)))
		error = -EFAULT;
out_free:
	kvfree(buffer);
	return error;
}

int
xfs_attrlist_by_handle(
	struct file		*parfilp,
	struct xfs_fsop_attrlist_handlereq __user *p)
{
	struct xfs_fsop_attrlist_handlereq al_hreq;
	struct dentry		*dentry;
	int			error = -ENOMEM;

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;
	if (copy_from_user(&al_hreq, p, sizeof(al_hreq)))
		return -EFAULT;

	dentry = xfs_handlereq_to_dentry(parfilp, &al_hreq.hreq);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);

	error = xfs_ioc_attr_list(XFS_I(d_inode(dentry)), al_hreq.buffer,
				  al_hreq.buflen, al_hreq.flags, &p->pos);
	dput(dentry);
	return error;
}

static int
xfs_attrmulti_attr_get(
	struct inode		*inode,
	unsigned char		*name,
	unsigned char		__user *ubuf,
	uint32_t		*len,
	uint32_t		flags)
{
	struct xfs_da_args	args = {
		.dp		= XFS_I(inode),
		.attr_filter	= xfs_attr_filter(flags),
		.name		= name,
		.namelen	= strlen(name),
		.valuelen	= *len,
	};
	int			error;

	if (*len > XFS_XATTR_SIZE_MAX)
		return -EINVAL;

	error = xfs_attr_get(&args);
	if (error)
		goto out_kfree;

	*len = args.valuelen;
	if (copy_to_user(ubuf, args.value, args.valuelen))
		error = -EFAULT;

out_kfree:
	kvfree(args.value);
	return error;
}

static int
xfs_attrmulti_attr_set(
	struct inode		*inode,
	unsigned char		*name,
	const unsigned char	__user *ubuf,
	uint32_t		len,
	uint32_t		flags)
{
	struct xfs_da_args	args = {
		.dp		= XFS_I(inode),
		.attr_filter	= xfs_attr_filter(flags),
		.name		= name,
		.namelen	= strlen(name),
	};
	int			error;

	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
		return -EPERM;

	if (ubuf) {
		if (len > XFS_XATTR_SIZE_MAX)
			return -EINVAL;
		args.value = memdup_user(ubuf, len);
		if (IS_ERR(args.value))
			return PTR_ERR(args.value);
		args.valuelen = len;
	}

	error = xfs_attr_change(&args, xfs_xattr_flags(flags, args.value));
	if (!error && (flags & XFS_IOC_ATTR_ROOT))
		xfs_forget_acl(inode, name);
	kfree(args.value);
	return error;
}

int
xfs_ioc_attrmulti_one(
	struct file		*parfilp,
	struct inode		*inode,
	uint32_t		opcode,
	void __user		*uname,
	void __user		*value,
	uint32_t		*len,
	uint32_t		flags)
{
	unsigned char		*name;
	int			error;

	if ((flags & XFS_IOC_ATTR_ROOT) && (flags & XFS_IOC_ATTR_SECURE))
		return -EINVAL;

	name = strndup_user(uname, MAXNAMELEN);
	if (IS_ERR(name))
		return PTR_ERR(name);

	switch (opcode) {
	case ATTR_OP_GET:
		error = xfs_attrmulti_attr_get(inode, name, value, len, flags);
		break;
	case ATTR_OP_REMOVE:
		value = NULL;
		*len = 0;
		fallthrough;
	case ATTR_OP_SET:
		error = mnt_want_write_file(parfilp);
		if (error)
			break;
		error = xfs_attrmulti_attr_set(inode, name, value, *len, flags);
		mnt_drop_write_file(parfilp);
		break;
	default:
		error = -EINVAL;
		break;
	}

	kfree(name);
	return error;
}

int
xfs_attrmulti_by_handle(
	struct file		*parfilp,
	void			__user *arg)
{
	int			error;
	xfs_attr_multiop_t	*ops;
	xfs_fsop_attrmulti_handlereq_t am_hreq;
	struct dentry		*dentry;
	unsigned int		i, size;

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;
	if (copy_from_user(&am_hreq, arg, sizeof(xfs_fsop_attrmulti_handlereq_t)))
		return -EFAULT;

	/* overflow check */
	if (am_hreq.opcount >= INT_MAX / sizeof(xfs_attr_multiop_t))
		return -E2BIG;

	dentry = xfs_handlereq_to_dentry(parfilp, &am_hreq.hreq);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);

	error = -E2BIG;
	size = am_hreq.opcount * sizeof(xfs_attr_multiop_t);
	if (!size || size > 16 * PAGE_SIZE)
		goto out_dput;

	ops = memdup_user(am_hreq.ops, size);
	if (IS_ERR(ops)) {
		error = PTR_ERR(ops);
		goto out_dput;
	}

	error = 0;
	for (i = 0; i < am_hreq.opcount; i++) {
		ops[i].am_error = xfs_ioc_attrmulti_one(parfilp,
				d_inode(dentry), ops[i].am_opcode,
				ops[i].am_attrname, ops[i].am_attrvalue,
				&ops[i].am_length, ops[i].am_flags);
	}

	if (copy_to_user(am_hreq.ops, ops, size))
		error = -EFAULT;

	kfree(ops);
 out_dput:
	dput(dentry);
	return error;
}