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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: David Disseldorp <ddiss@suse.de>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
David Disseldorp 2019-04-18 14:15:48 +02:00 committed by Ilya Dryomov
parent 100cc610a5
commit 2b2abcac8c
1 changed files with 35 additions and 29 deletions
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52
fs/ceph/xattr.c
View File

@ -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;