linux-kernel - [PATCH] thunderbolt: For dev authorization changes, include the actual event in udev change notification

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Message-Id: <20210723012835.1935471-1-rajatja@google.com>
Date:   Thu, 22 Jul 2021 18:28:34 -0700
From:   Rajat Jain <rajatja@...gle.com>
To:     Andreas Noever <andreas.noever@...il.com>,
        Michael Jamet <michael.jamet@...el.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Yehezkel Bernat <YehezkelShB@...il.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Rajat Jain <rajatja@...gle.com>, rajatxjain@...il.com
Subject: [PATCH] thunderbolt: For dev authorization changes, include the
 actual event in udev change notification

For security, we would like to monitor and track when the
thunderbolt devices are authorized and deauthorized. Currently
the userspace gets a udev change notification when there is a
change, but the state may have changed (again) by the time we
look at the authorized attribute in sysfs. So an authorization
event may go unnoticed. Thus make it easier by informing the
actual change (authorized/deauthorized) in the udev change
notification.

Signed-off-by: Rajat Jain <rajatja@...gle.com>
---
 drivers/thunderbolt/switch.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index 83b1ef3d5d03..5d3e9dcba44a 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -1499,6 +1499,7 @@ static ssize_t authorized_show(struct device *dev,
 static int disapprove_switch(struct device *dev, void *not_used)
 {
 	struct tb_switch *sw;
+	char *envp[] = { "AUTHORIZED=0", NULL };
 
 	sw = tb_to_switch(dev);
 	if (sw && sw->authorized) {
@@ -1514,7 +1515,7 @@ static int disapprove_switch(struct device *dev, void *not_used)
 			return ret;
 
 		sw->authorized = 0;
-		kobject_uevent(&sw->dev.kobj, KOBJ_CHANGE);
+		kobject_uevent_env(&sw->dev.kobj, KOBJ_CHANGE, envp);
 	}
 
 	return 0;
@@ -1523,6 +1524,8 @@ static int disapprove_switch(struct device *dev, void *not_used)
 static int tb_switch_set_authorized(struct tb_switch *sw, unsigned int val)
 {
 	int ret = -EINVAL;
+	char envp_string[13];
+	char *envp[] = { envp_string, NULL };
 
 	if (!mutex_trylock(&sw->tb->lock))
 		return restart_syscall();
@@ -1560,7 +1563,8 @@ static int tb_switch_set_authorized(struct tb_switch *sw, unsigned int val)
 	if (!ret) {
 		sw->authorized = val;
 		/* Notify status change to the userspace */
-		kobject_uevent(&sw->dev.kobj, KOBJ_CHANGE);
+		sprintf(envp_string, "AUTHORIZED=%u", val);
+		kobject_uevent_env(&sw->dev.kobj, KOBJ_CHANGE, envp);
 	}
 
 unlock:
-- 
2.32.0.432.gabb21c7263-goog