diff options
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/Kconfig | 24 | ||||
| -rw-r--r-- | drivers/tty/tty_io.c | 3 | ||||
| -rw-r--r-- | drivers/tty/tty_ldisc.c | 47 |
3 files changed, 74 insertions, 0 deletions
diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig index 0840d27381ea..e0a04bfc873e 100644 --- a/drivers/tty/Kconfig +++ b/drivers/tty/Kconfig @@ -441,4 +441,28 @@ config VCC depends on SUN_LDOMS help Support for Sun logical domain consoles. + +config LDISC_AUTOLOAD + bool "Automatically load TTY Line Disciplines" + default y + help + Historically the kernel has always automatically loaded any + line discipline that is in a kernel module when a user asks + for it to be loaded with the TIOCSETD ioctl, or through other + means. This is not always the best thing to do on systems + where you know you will not be using some of the more + "ancient" line disciplines, so prevent the kernel from doing + this unless the request is coming from a process with the + CAP_SYS_MODULE permissions. + + Say 'Y' here if you trust your userspace users to do the right + thing, or if you have only provided the line disciplines that + you know you will be using, or if you wish to continue to use + the traditional method of on-demand loading of these modules + by any user. + + This functionality can be changed at runtime with the + dev.tty.ldisc_autoload sysctl, this configuration option will + only set the default value of this functionality. + endif # TTY diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 21ffcce16927..5fa250157025 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -513,6 +513,8 @@ static const struct file_operations hung_up_tty_fops = { static DEFINE_SPINLOCK(redirect_lock); static struct file *redirect; +extern void tty_sysctl_init(void); + /** * tty_wakeup - request more data * @tty: terminal @@ -3483,6 +3485,7 @@ void console_sysfs_notify(void) */ int __init tty_init(void) { + tty_sysctl_init(); cdev_init(&tty_cdev, &tty_fops); if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) || register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0) diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c index 45eda69b150c..e38f104db174 100644 --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -156,6 +156,13 @@ static void put_ldops(struct tty_ldisc_ops *ldops) * takes tty_ldiscs_lock to guard against ldisc races */ +#if defined(CONFIG_LDISC_AUTOLOAD) + #define INITIAL_AUTOLOAD_STATE 1 +#else + #define INITIAL_AUTOLOAD_STATE 0 +#endif +static int tty_ldisc_autoload = INITIAL_AUTOLOAD_STATE; + static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc) { struct tty_ldisc *ld; @@ -170,6 +177,8 @@ static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc) */ ldops = get_ldops(disc); if (IS_ERR(ldops)) { + if (!capable(CAP_SYS_MODULE) && !tty_ldisc_autoload) + return ERR_PTR(-EPERM); request_module("tty-ldisc-%d", disc); ldops = get_ldops(disc); if (IS_ERR(ldops)) @@ -845,3 +854,41 @@ void tty_ldisc_deinit(struct tty_struct *tty) tty_ldisc_put(tty->ldisc); tty->ldisc = NULL; } + +static int zero; +static int one = 1; +static struct ctl_table tty_table[] = { + { + .procname = "ldisc_autoload", + .data = &tty_ldisc_autoload, + .maxlen = sizeof(tty_ldisc_autoload), + .mode = 0644, + .proc_handler = proc_dointvec, + .extra1 = &zero, + .extra2 = &one, + }, + { } +}; + +static struct ctl_table tty_dir_table[] = { + { + .procname = "tty", + .mode = 0555, + .child = tty_table, + }, + { } +}; + +static struct ctl_table tty_root_table[] = { + { + .procname = "dev", + .mode = 0555, + .child = tty_dir_table, + }, + { } +}; + +void tty_sysctl_init(void) +{ + register_sysctl_table(tty_root_table); +} |