Commit 2b2abcac authored by David Disseldorp's avatar David Disseldorp Committed by Ilya Dryomov
Browse files

ceph: fix listxattr vxattr buffer length calculation 



ceph_listxattr() incorrectly returns a length based on the static
ceph_vxattrs_name_size() value, which only takes into account whether
vxattrs are hidden, ignoring vxattr.exists_cb().

When filling the xattr buffer ceph_listxattr() checks VXATTR_FLAG_HIDDEN
and vxattr.exists_cb(). If both are false, we return an incorrect
(oversize) length.

Fix this behaviour by always calculating the vxattrs length at runtime,
taking both vxattr.hidden and vxattr.exists_cb() into account.

This bug is only exposed with the new "ceph.snap.btime" vxattr, as all
other vxattrs with a non-null exists_cb also carry VXATTR_FLAG_HIDDEN.

Signed-off-by: default avatarDavid Disseldorp <ddiss@suse.de>
Reviewed-by: default avatar"Yan, Zheng" <zyan@redhat.com>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent 100cc610

fs/ceph/xattr.c

+30 −24
Original line number Diff line number Diff line
@@ -924,10 +924,9 @@ ssize_t ceph_listxattr(struct dentry *dentry, char *names, size_t size) 
	struct inode *inode = d_inode(dentry);

	struct ceph_inode_info *ci = ceph_inode(inode);

	struct ceph_vxattr *vxattrs = ceph_inode_vxattrs(inode);

	u32 vir_namelen = 0;

	bool len_only = (size == 0);

	u32 namelen;

	int err;

	u32 len;

	int i;



	spin_lock(&ci->i_ceph_lock);
@@ -946,38 +945,45 @@ ssize_t ceph_listxattr(struct dentry *dentry, char *names, size_t size) 
	err = __build_xattrs(inode);

	if (err < 0)

		goto out;

	/*

	 * Start with virtual dir xattr names (if any) (including

	 * terminating '\0' characters for each).

	 */

	vir_namelen = ceph_vxattrs_name_size(vxattrs);



	/* adding 1 byte per each variable due to the null termination */

	/* add 1 byte for each xattr due to the null termination */

	namelen = ci->i_xattrs.names_size + ci->i_xattrs.count;

	if (!len_only) {

		if (namelen > size) {

			err = -ERANGE;

	if (size && vir_namelen + namelen > size)

		goto out;



	err = namelen + vir_namelen;

	if (size == 0)

			goto out;



		}

		names = __copy_xattr_names(ci, names);

		size -= namelen;

	}





	/* virtual xattr names, too */

	err = namelen;

	if (vxattrs) {

		for (i = 0; vxattrs[i].name; i++) {

			if (!(vxattrs[i].flags & VXATTR_FLAG_HIDDEN) &&

			    !(vxattrs[i].exists_cb &&

			      !vxattrs[i].exists_cb(ci))) {

				len = sprintf(names, "%s", vxattrs[i].name);

				names += len + 1;

				err += len + 1;

			size_t this_len;



			if (vxattrs[i].flags & VXATTR_FLAG_HIDDEN)

				continue;

			if (vxattrs[i].exists_cb && !vxattrs[i].exists_cb(ci))

				continue;



			this_len = strlen(vxattrs[i].name) + 1;

			namelen += this_len;

			if (len_only)

				continue;



			if (this_len > size) {

				err = -ERANGE;

				goto out;

			}



			memcpy(names, vxattrs[i].name, this_len);

			names += this_len;

			size -= this_len;

		}

	}



	err = namelen;

out:

	spin_unlock(&ci->i_ceph_lock);

	return err;

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