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ANDROID: xt_qtaguid: Remove tag_entry from process list on untag

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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
(cherry picked from commit c2ab93b45b5cdc426868fb8793ada2cac20568ef)
This commit is contained in:
Kalesh Singh
2021-01-11 01:26:18 -05:00
committed by Chris
parent 1d76cb0f89
commit 697e690da3
1 changed files with 8 additions and 3 deletions
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11
net/netfilter/xt_qtaguid.c
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@@ -2418,15 +2418,20 @@ 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,