userns: Allow chown and setgid preservation
- Allow chown if CAP_CHOWN is present in the current user namespace
and the uid of the inode maps into the current user namespace, and
the destination uid or gid maps into the current user namespace.
- Allow perserving setgid when changing an inode if CAP_FSETID is
present in the current user namespace and the owner of the file has
a mapping into the current user namespace.
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/fs/attr.c b/fs/attr.c
index cce7df5..1449adb 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -49,14 +49,15 @@
/* Make sure a caller can chown. */
if ((ia_valid & ATTR_UID) &&
(!uid_eq(current_fsuid(), inode->i_uid) ||
- !uid_eq(attr->ia_uid, inode->i_uid)) && !capable(CAP_CHOWN))
+ !uid_eq(attr->ia_uid, inode->i_uid)) &&
+ !inode_capable(inode, CAP_CHOWN))
return -EPERM;
/* Make sure caller can chgrp. */
if ((ia_valid & ATTR_GID) &&
(!uid_eq(current_fsuid(), inode->i_uid) ||
(!in_group_p(attr->ia_gid) && !gid_eq(attr->ia_gid, inode->i_gid))) &&
- !capable(CAP_CHOWN))
+ !inode_capable(inode, CAP_CHOWN))
return -EPERM;
/* Make sure a caller can chmod. */
@@ -65,7 +66,8 @@
return -EPERM;
/* Also check the setgid bit! */
if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
- inode->i_gid) && !capable(CAP_FSETID))
+ inode->i_gid) &&
+ !inode_capable(inode, CAP_FSETID))
attr->ia_mode &= ~S_ISGID;
}
@@ -157,7 +159,8 @@
if (ia_valid & ATTR_MODE) {
umode_t mode = attr->ia_mode;
- if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
+ if (!in_group_p(inode->i_gid) &&
+ !inode_capable(inode, CAP_FSETID))
mode &= ~S_ISGID;
inode->i_mode = mode;
}