[PATCH v2] tty: Add comments for tty-ldisc module loading logic

From: Zijun Hu
Date: Fri Dec 15 2023 - 08:41:53 EST


Current tty-ldisc module loading logic within tty_ldisc_get()
is prone to mislead beginner that the module is able to be loaded
by a user without capability CAP_SYS_MODULE, add comments to make
the logic easy to undertand.

Signed-off-by: Zijun Hu <quic_zijuhu@xxxxxxxxxxx>
---
Changes in v2:
- Remove condition checking changes

drivers/tty/tty_ldisc.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 3f68e213df1f..34526ffaccbc 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -150,6 +150,10 @@ static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc)
*/
ldops = get_ldops(disc);
if (IS_ERR(ldops)) {
+ /*
+ * Always request tty-ldisc module regardless of user's
+ * CAP_SYS_MODULE if autoload is enabled.
+ */
if (!capable(CAP_SYS_MODULE) && !tty_ldisc_autoload)
return ERR_PTR(-EPERM);
request_module("tty-ldisc-%d", disc);
--
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