mirror of https://github.com/torvalds/linux.git
833d2b3a07
A few callers want to lock for a rename and already have both dentries. Also debugfs does want to perform a lookup but doesn't want permission checking, so start_renaming_dentry() cannot be used. This patch introduces start_renaming_two_dentries() which is given both dentries. debugfs performs one lookup itself. As it will only continue with a negative dentry and as those cannot be renamed or unlinked, it is safe to do the lookup before getting the rename locks. overlayfs uses start_renaming_two_dentries() in three places and selinux uses it twice in sel_make_policy_nodes(). In sel_make_policy_nodes() we now lock for rename twice instead of just once so the combined operation is no longer atomic w.r.t the parent directory locks. As selinux_state.policy_mutex is held across the whole operation this does not open up any interesting races. Reviewed-by: Amir Goldstein <amir73il@gmail.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: NeilBrown <neil@brown.name> Link: https://patch.msgid.link/20251113002050.676694-13-neilb@ownmail.net Signed-off-by: Christian Brauner <brauner@kernel.org> |
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