[PATCH 5.4 205/215] tty: n_gsm: require CAP_NET_ADMIN to attach N_GSM0710 ldisc

Greg Kroah-Hartman
2024-04-11T10:24:03Z

From: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

commit 67c37756898a5a6b2941a13ae7260c89b54e0d88 upstream.

Any unprivileged user can attach N_GSM0710 ldisc, but it requires
CAP_NET_ADMIN to create a GSM network anyway.

Require initial namespace CAP_NET_ADMIN to do that.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Link: https://lore.kernel.org/r/20230731185942.279611-1-cascardo@canonical.com
From: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/n_gsm.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2567,6 +2567,9 @@ static int gsmld_open(struct tty_struct
struct gsm_mux *gsm;
int ret;

+ if (!capable(CAP_NET_ADMIN))
+ return -EPERM;
+
if (tty->ops->write == NULL)
return -EINVAL;