diff options
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/Makefile | 2 | ||||
| -rw-r--r-- | drivers/tty/tty_io.c | 547 | ||||
| -rw-r--r-- | drivers/tty/tty_jobctrl.c | 554 |
3 files changed, 566 insertions, 537 deletions
diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile index 6983b5a49ec3..f02becdb3e33 100644 --- a/drivers/tty/Makefile +++ b/drivers/tty/Makefile @@ -1,6 +1,6 @@ obj-$(CONFIG_TTY) += tty_io.o n_tty.o tty_ioctl.o tty_ldisc.o \ tty_buffer.o tty_port.o tty_mutex.o \ - tty_ldsem.o tty_baudrate.o + tty_ldsem.o tty_baudrate.o tty_jobctrl.o obj-$(CONFIG_LEGACY_PTYS) += pty.o obj-$(CONFIG_UNIX98_PTYS) += pty.o obj-$(CONFIG_AUDIT) += tty_audit.o diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 8244b6199784..0c150b5a9dd6 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -377,65 +377,6 @@ struct tty_driver *tty_find_polling_driver(char *name, int *line) EXPORT_SYMBOL_GPL(tty_find_polling_driver); #endif -static int is_ignored(int sig) -{ - return (sigismember(¤t->blocked, sig) || - current->sighand->action[sig-1].sa.sa_handler == SIG_IGN); -} - -/** - * tty_check_change - check for POSIX terminal changes - * @tty: tty to check - * - * If we try to write to, or set the state of, a terminal and we're - * not in the foreground, send a SIGTTOU. If the signal is blocked or - * ignored, go ahead and perform the operation. (POSIX 7.2) - * - * Locking: ctrl_lock - */ - -int __tty_check_change(struct tty_struct *tty, int sig) -{ - unsigned long flags; - struct pid *pgrp, *tty_pgrp; - int ret = 0; - - if (current->signal->tty != tty) - return 0; - - rcu_read_lock(); - pgrp = task_pgrp(current); - - spin_lock_irqsave(&tty->ctrl_lock, flags); - tty_pgrp = tty->pgrp; - spin_unlock_irqrestore(&tty->ctrl_lock, flags); - - if (tty_pgrp && pgrp != tty->pgrp) { - if (is_ignored(sig)) { - if (sig == SIGTTIN) - ret = -EIO; - } else if (is_current_pgrp_orphaned()) - ret = -EIO; - else { - kill_pgrp(pgrp, sig, 1); - set_thread_flag(TIF_SIGPENDING); - ret = -ERESTARTSYS; - } - } - rcu_read_unlock(); - - if (!tty_pgrp) - tty_warn(tty, "sig=%d, tty->pgrp == NULL!\n", sig); - - return ret; -} - -int tty_check_change(struct tty_struct *tty) -{ - return __tty_check_change(tty, SIGTTOU); -} -EXPORT_SYMBOL(tty_check_change); - static ssize_t hung_up_tty_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { @@ -509,79 +450,6 @@ static const struct file_operations hung_up_tty_fops = { static DEFINE_SPINLOCK(redirect_lock); static struct file *redirect; - -void proc_clear_tty(struct task_struct *p) -{ - unsigned long flags; - struct tty_struct *tty; - spin_lock_irqsave(&p->sighand->siglock, flags); - tty = p->signal->tty; - p->signal->tty = NULL; - spin_unlock_irqrestore(&p->sighand->siglock, flags); - tty_kref_put(tty); -} - -/** - * proc_set_tty - set the controlling terminal - * - * Only callable by the session leader and only if it does not already have - * a controlling terminal. - * - * Caller must hold: tty_lock() - * a readlock on tasklist_lock - * sighand lock - */ -static void __proc_set_tty(struct tty_struct *tty) -{ - unsigned long flags; - - spin_lock_irqsave(&tty->ctrl_lock, flags); - /* - * The session and fg pgrp references will be non-NULL if - * tiocsctty() is stealing the controlling tty - */ - put_pid(tty->session); - put_pid(tty->pgrp); - tty->pgrp = get_pid(task_pgrp(current)); - spin_unlock_irqrestore(&tty->ctrl_lock, flags); - tty->session = get_pid(task_session(current)); - if (current->signal->tty) { - tty_debug(tty, "current tty %s not NULL!!\n", - current->signal->tty->name); - tty_kref_put(current->signal->tty); - } - put_pid(current->signal->tty_old_pgrp); - current->signal->tty = tty_kref_get(tty); - current->signal->tty_old_pgrp = NULL; -} - -static void proc_set_tty(struct tty_struct *tty) -{ - spin_lock_irq(¤t->sighand->siglock); - __proc_set_tty(tty); - spin_unlock_irq(¤t->sighand->siglock); -} - -struct tty_struct *get_current_tty(void) -{ - struct tty_struct *tty; - unsigned long flags; - - spin_lock_irqsave(¤t->sighand->siglock, flags); - tty = tty_kref_get(current->signal->tty); - spin_unlock_irqrestore(¤t->sighand->siglock, flags); - return tty; -} -EXPORT_SYMBOL_GPL(get_current_tty); - -static void session_clear_tty(struct pid *session) -{ - struct task_struct *p; - do_each_pid_task(session, PIDTYPE_SID, p) { - proc_clear_tty(p); - } while_each_pid_task(session, PIDTYPE_SID, p); -} - /** * tty_wakeup - request more data * @tty: terminal @@ -609,60 +477,6 @@ void tty_wakeup(struct tty_struct *tty) EXPORT_SYMBOL_GPL(tty_wakeup); /** - * tty_signal_session_leader - sends SIGHUP to session leader - * @tty controlling tty - * @exit_session if non-zero, signal all foreground group processes - * - * Send SIGHUP and SIGCONT to the session leader and its process group. - * Optionally, signal all processes in the foreground process group. - * - * Returns the number of processes in the session with this tty - * as their controlling terminal. This value is used to drop - * tty references for those processes. - */ -static int tty_signal_session_leader(struct tty_struct *tty, int exit_session) -{ - struct task_struct *p; - int refs = 0; - struct pid *tty_pgrp = NULL; - - read_lock(&tasklist_lock); - if (tty->session) { - do_each_pid_task(tty->session, PIDTYPE_SID, p) { - spin_lock_irq(&p->sighand->siglock); - if (p->signal->tty == tty) { - p->signal->tty = NULL; - /* We defer the dereferences outside fo - the tasklist lock */ - refs++; - } - if (!p->signal->leader) { - spin_unlock_irq(&p->sighand->siglock); - continue; - } - __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p); - __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p); - put_pid(p->signal->tty_old_pgrp); /* A noop */ - spin_lock(&tty->ctrl_lock); - tty_pgrp = get_pid(tty->pgrp); - if (tty->pgrp) - p->signal->tty_old_pgrp = get_pid(tty->pgrp); - spin_unlock(&tty->ctrl_lock); - spin_unlock_irq(&p->sighand->siglock); - } while_each_pid_task(tty->session, PIDTYPE_SID, p); - } - read_unlock(&tasklist_lock); - - if (tty_pgrp) { - if (exit_session) - kill_pgrp(tty_pgrp, SIGHUP, exit_session); - put_pid(tty_pgrp); - } - - return refs; -} - -/** * __tty_hangup - actual handler for hangup events * @work: tty device * @@ -840,7 +654,7 @@ void tty_vhangup_self(void) * is complete. That guarantee is necessary for security reasons. */ -static void tty_vhangup_session(struct tty_struct *tty) +void tty_vhangup_session(struct tty_struct *tty) { tty_debug_hangup(tty, "session hangup\n"); __tty_hangup(tty, 1); @@ -862,106 +676,6 @@ int tty_hung_up_p(struct file *filp) EXPORT_SYMBOL(tty_hung_up_p); /** - * disassociate_ctty - disconnect controlling tty - * @on_exit: true if exiting so need to "hang up" the session - * - * This function is typically called only by the session leader, when - * it wants to disassociate itself from its controlling tty. - * - * It performs the following functions: - * (1) Sends a SIGHUP and SIGCONT to the foreground process group - * (2) Clears the tty from being controlling the session - * (3) Clears the controlling tty for all processes in the - * session group. - * - * The argument on_exit is set to 1 if called when a process is - * exiting; it is 0 if called by the ioctl TIOCNOTTY. - * - * Locking: - * BTM is taken for hysterical raisins, and held when - * called from no_tty(). - * tty_mutex is taken to protect tty - * ->siglock is taken to protect ->signal/->sighand - * tasklist_lock is taken to walk process list for sessions - * ->siglock is taken to protect ->signal/->sighand - */ - -void disassociate_ctty(int on_exit) -{ - struct tty_struct *tty; - - if (!current->signal->leader) - return; - - tty = get_current_tty(); - if (tty) { - if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY) { - tty_vhangup_session(tty); - } else { - struct pid *tty_pgrp = tty_get_pgrp(tty); - if (tty_pgrp) { - kill_pgrp(tty_pgrp, SIGHUP, on_exit); - if (!on_exit) - kill_pgrp(tty_pgrp, SIGCONT, on_exit); - put_pid(tty_pgrp); - } - } - tty_kref_put(tty); - - } else if (on_exit) { - struct pid *old_pgrp; - spin_lock_irq(¤t->sighand->siglock); - old_pgrp = current->signal->tty_old_pgrp; - current->signal->tty_old_pgrp = NULL; - spin_unlock_irq(¤t->sighand->siglock); - if (old_pgrp) { - kill_pgrp(old_pgrp, SIGHUP, on_exit); - kill_pgrp(old_pgrp, SIGCONT, on_exit); - put_pid(old_pgrp); - } - return; - } - - spin_lock_irq(¤t->sighand->siglock); - put_pid(current->signal->tty_old_pgrp); - current->signal->tty_old_pgrp = NULL; - - tty = tty_kref_get(current->signal->tty); - if (tty) { - unsigned long flags; - spin_lock_irqsave(&tty->ctrl_lock, flags); - put_pid(tty->session); - put_pid(tty->pgrp); - tty->session = NULL; - tty->pgrp = NULL; - spin_unlock_irqrestore(&tty->ctrl_lock, flags); - tty_kref_put(tty); - } else - tty_debug_hangup(tty, "no current tty\n"); - - spin_unlock_irq(¤t->sighand->siglock); - /* Now clear signal->tty under the lock */ - read_lock(&tasklist_lock); - session_clear_tty(task_session(current)); - read_unlock(&tasklist_lock); -} - -/** - * - * no_tty - Ensure the current process does not have a controlling tty - */ -void no_tty(void) -{ - /* FIXME: Review locking here. The tty_lock never covered any race - between a new association and proc_clear_tty but possible we need - to protect against this anyway */ - struct task_struct *tsk = current; - disassociate_ctty(0); - proc_clear_tty(tsk); -} - - -/** * stop_tty - propagate flow control * @tty: tty to stop * @@ -2163,38 +1877,13 @@ retry_open: } clear_bit(TTY_HUPPED, &tty->flags); - - read_lock(&tasklist_lock); - spin_lock_irq(¤t->sighand->siglock); noctty = (filp->f_flags & O_NOCTTY) || - (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) || - device == MKDEV(TTYAUX_MAJOR, 1) || - (tty->driver->type == TTY_DRIVER_TYPE_PTY && - tty->driver->subtype == PTY_TYPE_MASTER); - - if (!noctty && - current->signal->leader && - !current->signal->tty && - tty->session == NULL) { - /* - * Don't let a process that only has write access to the tty - * obtain the privileges associated with having a tty as - * controlling terminal (being able to reopen it with full - * access through /dev/tty, being able to perform pushback). - * Many distributions set the group of all ttys to "tty" and - * grant write-only access to all terminals for setgid tty - * binaries, which should not imply full privileges on all ttys. - * - * This could theoretically break old code that performs open() - * on a write-only file descriptor. In that case, it might be - * necessary to also permit this if - * inode_permission(inode, MAY_READ) == 0. - */ - if (filp->f_mode & FMODE_READ) - __proc_set_tty(tty); - } - spin_unlock_irq(¤t->sighand->siglock); - read_unlock(&tasklist_lock); + (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) || + device == MKDEV(TTYAUX_MAJOR, 1) || + (tty->driver->type == TTY_DRIVER_TYPE_PTY && + tty->driver->subtype == PTY_TYPE_MASTER); + if (!noctty) + tty_open_proc_set_tty(filp, tty); tty_unlock(tty); return 0; } @@ -2457,211 +2146,6 @@ static int fionbio(struct file *file, int __user *p) } /** - * tiocsctty - set controlling tty - * @tty: tty structure - * @arg: user argument - * - * This ioctl is used to manage job control. It permits a session - * leader to set this tty as the controlling tty for the session. - * - * Locking: - * Takes tty_lock() to serialize proc_set_tty() for this tty - * Takes tasklist_lock internally to walk sessions - * Takes ->siglock() when updating signal->tty - */ - -static int tiocsctty(struct tty_struct *tty, struct file *file, int arg) -{ - int ret = 0; - - tty_lock(tty); - read_lock(&tasklist_lock); - - if (current->signal->leader && (task_session(current) == tty->session)) - goto unlock; - - /* - * The process must be a session leader and - * not have a controlling tty already. - */ - if (!current->signal->leader || current->signal->tty) { - ret = -EPERM; - goto unlock; - } - - if (tty->session) { - /* - * This tty is already the controlling - * tty for another session group! - */ - if (arg == 1 && capable(CAP_SYS_ADMIN)) { - /* - * Steal it away - */ - session_clear_tty(tty->session); - } else { - ret = -EPERM; - goto unlock; - } - } - - /* See the comment in tty_open(). */ - if ((file->f_mode & FMODE_READ) == 0 && !capable(CAP_SYS_ADMIN)) { - ret = -EPERM; - goto unlock; - } - - proc_set_tty(tty); -unlock: - read_unlock(&tasklist_lock); - tty_unlock(tty); - return ret; -} - -/** - * tty_get_pgrp - return a ref counted pgrp pid - * @tty: tty to read - * - * Returns a refcounted instance of the pid struct for the process - * group controlling the tty. - */ - -struct pid *tty_get_pgrp(struct tty_struct *tty) -{ - unsigned long flags; - struct pid *pgrp; - - spin_lock_irqsave(&tty->ctrl_lock, flags); - pgrp = get_pid(tty->pgrp); - spin_unlock_irqrestore(&tty->ctrl_lock, flags); - - return pgrp; -} -EXPORT_SYMBOL_GPL(tty_get_pgrp); - -/* - * This checks not only the pgrp, but falls back on the pid if no - * satisfactory pgrp is found. I dunno - gdb doesn't work correctly - * without this... - * - * The caller must hold rcu lock or the tasklist lock. - */ -static struct pid *session_of_pgrp(struct pid *pgrp) -{ - struct task_struct *p; - struct pid *sid = NULL; - - p = pid_task(pgrp, PIDTYPE_PGID); - if (p == NULL) - p = pid_task(pgrp, PIDTYPE_PID); - if (p != NULL) - sid = task_session(p); - - return sid; -} - -/** - * tiocgpgrp - get process group - * @tty: tty passed by user - * @real_tty: tty side of the tty passed by the user if a pty else the tty - * @p: returned pid - * - * Obtain the process group of the tty. If there is no process group - * return an error. - * - * Locking: none. Reference to current->signal->tty is safe. - */ - -static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) -{ - struct pid *pid; - int ret; - /* - * (tty == real_tty) is a cheap way of - * testing if the tty is NOT a master pty. - */ - if (tty == real_tty && current->signal->tty != real_tty) - return -ENOTTY; - pid = tty_get_pgrp(real_tty); - ret = put_user(pid_vnr(pid), p); - put_pid(pid); - return ret; -} - -/** - * tiocspgrp - attempt to set process group - * @tty: tty passed by user - * @real_tty: tty side device matching tty passed by user - * @p: pid pointer - * - * Set the process group of the tty to the session passed. Only - * permitted where the tty session is our session. - * - * Locking: RCU, ctrl lock - */ - -static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) -{ - struct pid *pgrp; - pid_t pgrp_nr; - int retval = tty_check_change(real_tty); - - if (retval == -EIO) - return -ENOTTY; - if (retval) - return retval; - if (!current->signal->tty || - (current->signal->tty != real_tty) || - (real_tty->session != task_session(current))) - return -ENOTTY; - if (get_user(pgrp_nr, p)) - return -EFAULT; - if (pgrp_nr < 0) - return -EINVAL; - rcu_read_lock(); - pgrp = find_vpid(pgrp_nr); - retval = -ESRCH; - if (!pgrp) - goto out_unlock; - retval = -EPERM; - if (session_of_pgrp(pgrp) != task_session(current)) - goto out_unlock; - retval = 0; - spin_lock_irq(&tty->ctrl_lock); - put_pid(real_tty->pgrp); - real_tty->pgrp = get_pid(pgrp); - spin_unlock_irq(&tty->ctrl_lock); -out_unlock: - rcu_read_unlock(); - return retval; -} - -/** - * tiocgsid - get session id - * @tty: tty passed by user - * @real_tty: tty side of the tty passed by the user if a pty else the tty - * @p: pointer to returned session id - * - * Obtain the session id of the tty. If there is no session - * return an error. - * - * Locking: none. Reference to current->signal->tty is safe. - */ - -static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) -{ - /* - * (tty == real_tty) is a cheap way of - * testing if the tty is NOT a master pty. - */ - if (tty == real_tty && current->signal->tty != real_tty) - return -ENOTTY; - if (!real_tty->session) - return -ENOTTY; - return put_user(pid_vnr(real_tty->session), p); -} - -/** * tiocsetd - set line discipline * @tty: tty device * @p: pointer to user data @@ -2920,19 +2404,6 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg) int excl = test_bit(TTY_EXCLUSIVE, &tty->flags); return put_user(excl, (int __user *)p); } - case TIOCNOTTY: - if (current->signal->tty != tty) - return -ENOTTY; - no_tty(); - return 0; - case TIOCSCTTY: - return tiocsctty(real_tty, file, arg); - case TIOCGPGRP: - return tiocgpgrp(tty, real_tty, p); - case TIOCSPGRP: - return tiocspgrp(tty, real_tty, p); - case TIOCGSID: - return tiocgsid(tty, real_tty, p); case TIOCGETD: return tiocgetd(tty, p); case TIOCSETD: @@ -2993,6 +2464,10 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg) case TIOCSSERIAL: tty_warn_deprecated_flags(p); break; + default: + retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg); + if (retval != -ENOIOCTLCMD) + return retval; } if (tty->ops->ioctl) { retval = tty->ops->ioctl(tty, cmd, arg); diff --git a/drivers/tty/tty_jobctrl.c b/drivers/tty/tty_jobctrl.c new file mode 100644 index 000000000000..e7032309ee87 --- /dev/null +++ b/drivers/tty/tty_jobctrl.c @@ -0,0 +1,554 @@ +/* + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +#include <linux/types.h> +#include <linux/errno.h> +#include <linux/signal.h> +#include <linux/sched/signal.h> +#include <linux/sched/task.h> +#include <linux/tty.h> +#include <linux/fcntl.h> +#include <linux/uaccess.h> + +static int is_ignored(int sig) +{ + return (sigismember(¤t->blocked, sig) || + current->sighand->action[sig-1].sa.sa_handler == SIG_IGN); +} + +/** + * tty_check_change - check for POSIX terminal changes + * @tty: tty to check + * + * If we try to write to, or set the state of, a terminal and we're + * not in the foreground, send a SIGTTOU. If the signal is blocked or + * ignored, go ahead and perform the operation. (POSIX 7.2) + * + * Locking: ctrl_lock + */ +int __tty_check_change(struct tty_struct *tty, int sig) +{ + unsigned long flags; + struct pid *pgrp, *tty_pgrp; + int ret = 0; + + if (current->signal->tty != tty) + return 0; + + rcu_read_lock(); + pgrp = task_pgrp(current); + + spin_lock_irqsave(&tty->ctrl_lock, flags); + tty_pgrp = tty->pgrp; + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + + if (tty_pgrp && pgrp != tty->pgrp) { + if (is_ignored(sig)) { + if (sig == SIGTTIN) + ret = -EIO; + } else if (is_current_pgrp_orphaned()) + ret = -EIO; + else { + kill_pgrp(pgrp, sig, 1); + set_thread_flag(TIF_SIGPENDING); + ret = -ERESTARTSYS; + } + } + rcu_read_unlock(); + + if (!tty_pgrp) + tty_warn(tty, "sig=%d, tty->pgrp == NULL!\n", sig); + + return ret; +} + +int tty_check_change(struct tty_struct *tty) +{ + return __tty_check_change(tty, SIGTTOU); +} +EXPORT_SYMBOL(tty_check_change); + +void proc_clear_tty(struct task_struct *p) +{ + unsigned long flags; + struct tty_struct *tty; + spin_lock_irqsave(&p->sighand->siglock, flags); + tty = p->signal->tty; + p->signal->tty = NULL; + spin_unlock_irqrestore(&p->sighand->siglock, flags); + tty_kref_put(tty); +} + +/** + * proc_set_tty - set the controlling terminal + * + * Only callable by the session leader and only if it does not already have + * a controlling terminal. + * + * Caller must hold: tty_lock() + * a readlock on tasklist_lock + * sighand lock + */ +static void __proc_set_tty(struct tty_struct *tty) +{ + unsigned long flags; + + spin_lock_irqsave(&tty->ctrl_lock, flags); + /* + * The session and fg pgrp references will be non-NULL if + * tiocsctty() is stealing the controlling tty + */ + put_pid(tty->session); + put_pid(tty->pgrp); + tty->pgrp = get_pid(task_pgrp(current)); + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + tty->session = get_pid(task_session(current)); + if (current->signal->tty) { + tty_debug(tty, "current tty %s not NULL!!\n", + current->signal->tty->name); + tty_kref_put(current->signal->tty); + } + put_pid(current->signal->tty_old_pgrp); + current->signal->tty = tty_kref_get(tty); + current->signal->tty_old_pgrp = NULL; +} + +static void proc_set_tty(struct tty_struct *tty) +{ + spin_lock_irq(¤t->sighand->siglock); + __proc_set_tty(tty); + spin_unlock_irq(¤t->sighand->siglock); +} + +/* + * Called by tty_open() to set the controlling tty if applicable. + */ +void tty_open_proc_set_tty(struct file *filp, struct tty_struct *tty) +{ + read_lock(&tasklist_lock); + spin_lock_irq(¤t->sighand->siglock); + if (current->signal->leader && + !current->signal->tty && + tty->session == NULL) { + /* + * Don't let a process that only has write access to the tty + * obtain the privileges associated with having a tty as + * controlling terminal (being able to reopen it with full + * access through /dev/tty, being able to perform pushback). + * Many distributions set the group of all ttys to "tty" and + * grant write-only access to all terminals for setgid tty + * binaries, which should not imply full privileges on all ttys. + * + * This could theoretically break old code that performs open() + * on a write-only file descriptor. In that case, it might be + * necessary to also permit this if + * inode_permission(inode, MAY_READ) == 0. + */ + if (filp->f_mode & FMODE_READ) + __proc_set_tty(tty); + } + spin_unlock_irq(¤t->sighand->siglock); + read_unlock(&tasklist_lock); +} + +struct tty_struct *get_current_tty(void) +{ + struct tty_struct *tty; + unsigned long flags; + + spin_lock_irqsave(¤t->sighand->siglock, flags); + tty = tty_kref_get(current->signal->tty); + spin_unlock_irqrestore(¤t->sighand->siglock, flags); + return tty; +} +EXPORT_SYMBOL_GPL(get_current_tty); + +/* + * Called from tty_release(). + */ +void session_clear_tty(struct pid *session) +{ + struct task_struct *p; + do_each_pid_task(session, PIDTYPE_SID, p) { + proc_clear_tty(p); + } while_each_pid_task(session, PIDTYPE_SID, p); +} + +/** + * tty_signal_session_leader - sends SIGHUP to session leader + * @tty controlling tty + * @exit_session if non-zero, signal all foreground group processes + * + * Send SIGHUP and SIGCONT to the session leader and its process group. + * Optionally, signal all processes in the foreground process group. + * + * Returns the number of processes in the session with this tty + * as their controlling terminal. This value is used to drop + * tty references for those processes. + */ +int tty_signal_session_leader(struct tty_struct *tty, int exit_session) +{ + struct task_struct *p; + int refs = 0; + struct pid *tty_pgrp = NULL; + + read_lock(&tasklist_lock); + if (tty->session) { + do_each_pid_task(tty->session, PIDTYPE_SID, p) { + spin_lock_irq(&p->sighand->siglock); + if (p->signal->tty == tty) { + p->signal->tty = NULL; + /* We defer the dereferences outside fo + the tasklist lock */ + refs++; + } + if (!p->signal->leader) { + spin_unlock_irq(&p->sighand->siglock); + continue; + } + __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p); + __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p); + put_pid(p->signal->tty_old_pgrp); /* A noop */ + spin_lock(&tty->ctrl_lock); + tty_pgrp = get_pid(tty->pgrp); + if (tty->pgrp) + p->signal->tty_old_pgrp = get_pid(tty->pgrp); + spin_unlock(&tty->ctrl_lock); + spin_unlock_irq(&p->sighand->siglock); + } while_each_pid_task(tty->session, PIDTYPE_SID, p); + } + read_unlock(&tasklist_lock); + + if (tty_pgrp) { + if (exit_session) + kill_pgrp(tty_pgrp, SIGHUP, exit_session); + put_pid(tty_pgrp); + } + + return refs; +} + +/** + * disassociate_ctty - disconnect controlling tty + * @on_exit: true if exiting so need to "hang up" the session + * + * This function is typically called only by the session leader, when + * it wants to disassociate itself from its controlling tty. + * + * It performs the following functions: + * (1) Sends a SIGHUP and SIGCONT to the foreground process group + * (2) Clears the tty from being controlling the session + * (3) Clears the controlling tty for all processes in the + * session group. + * + * The argument on_exit is set to 1 if called when a process is + * exiting; it is 0 if called by the ioctl TIOCNOTTY. + * + * Locking: + * BTM is taken for hysterical raisons, and held when + * called from no_tty(). + * tty_mutex is taken to protect tty + * ->siglock is taken to protect ->signal/->sighand + * tasklist_lock is taken to walk process list for sessions + * ->siglock is taken to protect ->signal/->sighand + */ +void disassociate_ctty(int on_exit) +{ + struct tty_struct *tty; + + if (!current->signal->leader) + return; + + tty = get_current_tty(); + if (tty) { + if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY) { + tty_vhangup_session(tty); + } else { + struct pid *tty_pgrp = tty_get_pgrp(tty); + if (tty_pgrp) { + kill_pgrp(tty_pgrp, SIGHUP, on_exit); + if (!on_exit) + kill_pgrp(tty_pgrp, SIGCONT, on_exit); + put_pid(tty_pgrp); + } + } + tty_kref_put(tty); + + } else if (on_exit) { + struct pid *old_pgrp; + spin_lock_irq(¤t->sighand->siglock); + old_pgrp = current->signal->tty_old_pgrp; + current->signal->tty_old_pgrp = NULL; + spin_unlock_irq(¤t->sighand->siglock); + if (old_pgrp) { + kill_pgrp(old_pgrp, SIGHUP, on_exit); + kill_pgrp(old_pgrp, SIGCONT, on_exit); + put_pid(old_pgrp); + } + return; + } + + spin_lock_irq(¤t->sighand->siglock); + put_pid(current->signal->tty_old_pgrp); + current->signal->tty_old_pgrp = NULL; + + tty = tty_kref_get(current->signal->tty); + if (tty) { + unsigned long flags; + spin_lock_irqsave(&tty->ctrl_lock, flags); + put_pid(tty->session); + put_pid(tty->pgrp); + tty->session = NULL; + tty->pgrp = NULL; + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + tty_kref_put(tty); + } + + spin_unlock_irq(¤t->sighand->siglock); + /* Now clear signal->tty under the lock */ + read_lock(&tasklist_lock); + session_clear_tty(task_session(current)); + read_unlock(&tasklist_lock); +} + +/** + * + * no_tty - Ensure the current process does not have a controlling tty + */ +void no_tty(void) +{ + /* FIXME: Review locking here. The tty_lock never covered any race + between a new association and proc_clear_tty but possible we need + to protect against this anyway */ + struct task_struct *tsk = current; + disassociate_ctty(0); + proc_clear_tty(tsk); +} + +/** + * tiocsctty - set controlling tty + * @tty: tty structure + * @arg: user argument + * + * This ioctl is used to manage job control. It permits a session + * leader to set this tty as the controlling tty for the session. + * + * Locking: + * Takes tty_lock() to serialize proc_set_tty() for this tty + * Takes tasklist_lock internally to walk sessions + * Takes ->siglock() when updating signal->tty + */ +static int tiocsctty(struct tty_struct *tty, struct file *file, int arg) +{ + int ret = 0; + + tty_lock(tty); + read_lock(&tasklist_lock); + + if (current->signal->leader && (task_session(current) == tty->session)) + goto unlock; + + /* + * The process must be a session leader and + * not have a controlling tty already. + */ + if (!current->signal->leader || current->signal->tty) { + ret = -EPERM; + goto unlock; + } + + if (tty->session) { + /* + * This tty is already the controlling + * tty for another session group! + */ + if (arg == 1 && capable(CAP_SYS_ADMIN)) { + /* + * Steal it away + */ + session_clear_tty(tty->session); + } else { + ret = -EPERM; + goto unlock; + } + } + + /* See the comment in tty_open_proc_set_tty(). */ + if ((file->f_mode & FMODE_READ) == 0 && !capable(CAP_SYS_ADMIN)) { + ret = -EPERM; + goto unlock; + } + + proc_set_tty(tty); +unlock: + read_unlock(&tasklist_lock); + tty_unlock(tty); + return ret; +} + +/** + * tty_get_pgrp - return a ref counted pgrp pid + * @tty: tty to read + * + * Returns a refcounted instance of the pid struct for the process + * group controlling the tty. + */ +struct pid *tty_get_pgrp(struct tty_struct *tty) +{ + unsigned long flags; + struct pid *pgrp; + + spin_lock_irqsave(&tty->ctrl_lock, flags); + pgrp = get_pid(tty->pgrp); + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + + return pgrp; +} +EXPORT_SYMBOL_GPL(tty_get_pgrp); + +/* + * This checks not only the pgrp, but falls back on the pid if no + * satisfactory pgrp is found. I dunno - gdb doesn't work correctly + * without this... + * + * The caller must hold rcu lock or the tasklist lock. + */ +static struct pid *session_of_pgrp(struct pid *pgrp) +{ + struct task_struct *p; + struct pid *sid = NULL; + + p = pid_task(pgrp, PIDTYPE_PGID); + if (p == NULL) + p = pid_task(pgrp, PIDTYPE_PID); + if (p != NULL) + sid = task_session(p); + + return sid; +} + +/** + * tiocgpgrp - get process group + * @tty: tty passed by user + * @real_tty: tty side of the tty passed by the user if a pty else the tty + * @p: returned pid + * + * Obtain the process group of the tty. If there is no process group + * return an error. + * + * Locking: none. Reference to current->signal->tty is safe. + */ +static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) +{ + struct pid *pid; + int ret; + /* + * (tty == real_tty) is a cheap way of + * testing if the tty is NOT a master pty. + */ + if (tty == real_tty && current->signal->tty != real_tty) + return -ENOTTY; + pid = tty_get_pgrp(real_tty); + ret = put_user(pid_vnr(pid), p); + put_pid(pid); + return ret; +} + +/** + * tiocspgrp - attempt to set process group + * @tty: tty passed by user + * @real_tty: tty side device matching tty passed by user + * @p: pid pointer + * + * Set the process group of the tty to the session passed. Only + * permitted where the tty session is our session. + * + * Locking: RCU, ctrl lock + */ +static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) +{ + struct pid *pgrp; + pid_t pgrp_nr; + int retval = tty_check_change(real_tty); + + if (retval == -EIO) + return -ENOTTY; + if (retval) + return retval; + if (!current->signal->tty || + (current->signal->tty != real_tty) || + (real_tty->session != task_session(current))) + return -ENOTTY; + if (get_user(pgrp_nr, p)) + return -EFAULT; + if (pgrp_nr < 0) + return -EINVAL; + rcu_read_lock(); + pgrp = find_vpid(pgrp_nr); + retval = -ESRCH; + if (!pgrp) + goto out_unlock; + retval = -EPERM; + if (session_of_pgrp(pgrp) != task_session(current)) + goto out_unlock; + retval = 0; + spin_lock_irq(&tty->ctrl_lock); + put_pid(real_tty->pgrp); + real_tty->pgrp = get_pid(pgrp); + spin_unlock_irq(&tty->ctrl_lock); +out_unlock: + rcu_read_unlock(); + return retval; +} + +/** + * tiocgsid - get session id + * @tty: tty passed by user + * @real_tty: tty side of the tty passed by the user if a pty else the tty + * @p: pointer to returned session id + * + * Obtain the session id of the tty. If there is no session + * return an error. + * + * Locking: none. Reference to current->signal->tty is safe. + */ +static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) +{ + /* + * (tty == real_tty) is a cheap way of + * testing if the tty is NOT a master pty. + */ + if (tty == real_tty && current->signal->tty != real_tty) + return -ENOTTY; + if (!real_tty->session) + return -ENOTTY; + return put_user(pid_vnr(real_tty->session), p); +} + +/* + * Called from tty_ioctl(). If tty is a pty then real_tty is the slave side, + * if not then tty == real_tty. + */ +long tty_jobctrl_ioctl(struct tty_struct *tty, struct tty_struct *real_tty, + struct file *file, unsigned int cmd, unsigned long arg) +{ + void __user *p = (void __user *)arg; + + switch (cmd) { + case TIOCNOTTY: + if (current->signal->tty != tty) + return -ENOTTY; + no_tty(); + return 0; + case TIOCSCTTY: + return tiocsctty(real_tty, file, arg); + case TIOCGPGRP: + return tiocgpgrp(tty, real_tty, p); + case TIOCSPGRP: + return tiocspgrp(tty, real_tty, p); + case TIOCGSID: + return tiocgsid(tty, real_tty, p); + } + return -ENOIOCTLCMD; +} |