Commit 108aabc2 authored Jan 11, 2021 by Kalesh Singh Committed by urevanth Mar 04, 2021

ANDROID: xt_qtaguid: Remove tag_entry from process list on untag



A sock_tag_entry can only be part of one process's
pqd_entry->sock_tag_list. Retagging the socket only updates
sock_tag_entry->tag, and does not add the tag entry to the current
process's pqd_entry list, nor update sock_tag_entry->pid.
So the sock_tag_entry is only ever present in the
pqd_entry list of the process that initially tagged the socket.

A sock_tag_entry can also get created and not be added to any process's
pqd_entry list. This happens if the process that initially tags the
socket has not opened /dev/xt_qtaguid.

ctrl_cmd_untag() supports untagging from a context other than the
process that initially tagged the socket. Currently, the sock_tag_entry is
only removed from its containing pqd_entry->sock_tag_list if the
process that does the untagging has opened /dev/xt_qtaguid. However, the
tag entry should always be deleted from its pqd entry list (if present).

Bug: 176919394
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Change-Id: I5b6f0c36c0ebefd98cc6873a4057104c7d885ccc
Git-commit: c2ab93b45b5cdc426868fb8793ada2cac20568ef
Git-repo: https://android.googlesource.com/kernel/msm


Signed-off-by: urevanth <urevanth@codeaurora.org>

parent 484764cb

net/netfilter/xt_qtaguid.c

+8 −3

Original line number	Diff line number	Diff line
		@@ -2424,15 +2424,20 @@ int qtaguid_untag(struct socket *el_socket, bool kernel)
		* At first, we want to catch user-space code that is not
		* opening the /dev/xt_qtaguid.
		*/
		if (IS_ERR_OR_NULL(pqd_entry) \|\| !sock_tag_entry->list.next) {
		if (IS_ERR_OR_NULL(pqd_entry))
		pr_warn_once("qtaguid: %s(): "
		"User space forgot to open /dev/xt_qtaguid? "
		"pid=%u tgid=%u sk_pid=%u, uid=%u\n", __func__,
		current->pid, current->tgid, sock_tag_entry->pid,
		from_kuid(&init_user_ns, current_fsuid()));
		} else {
		/*
		* This check is needed because tagging from a process that
		* didn’t open /dev/xt_qtaguid still adds the sock_tag_entry
		* to sock_tag_tree.
		*/
		if (sock_tag_entry->list.next)
		list_del(&sock_tag_entry->list);
		}

		spin_unlock_bh(&uid_tag_data_tree_lock);
		/*
		* We don't free tag_ref from the utd_entry here,