diff options
| -rw-r--r-- | include/linux/ptrace.h | 1 | ||||
| -rw-r--r-- | include/linux/sched.h | 2 | ||||
| -rw-r--r-- | kernel/exit.c | 3 | ||||
| -rw-r--r-- | kernel/ptrace.c | 42 | ||||
| -rw-r--r-- | kernel/signal.c | 13 |
5 files changed, 53 insertions, 8 deletions
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index ad754d1e0b13..4f224f169524 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -49,6 +49,7 @@ #define PTRACE_SEIZE 0x4206 #define PTRACE_INTERRUPT 0x4207 +#define PTRACE_LISTEN 0x4208 /* flags in @data for PTRACE_SEIZE */ #define PTRACE_SEIZE_DEVEL 0x80000000 /* temp flag for development */ diff --git a/include/linux/sched.h b/include/linux/sched.h index 1854def284f5..87f7ca7ed6f6 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1813,6 +1813,7 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t * #define JOBCTL_TRAP_STOP_BIT 19 /* trap for STOP */ #define JOBCTL_TRAP_NOTIFY_BIT 20 /* trap for NOTIFY */ #define JOBCTL_TRAPPING_BIT 21 /* switching to TRACED */ +#define JOBCTL_LISTENING_BIT 22 /* ptracer is listening for events */ #define JOBCTL_STOP_DEQUEUED (1 << JOBCTL_STOP_DEQUEUED_BIT) #define JOBCTL_STOP_PENDING (1 << JOBCTL_STOP_PENDING_BIT) @@ -1820,6 +1821,7 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t * #define JOBCTL_TRAP_STOP (1 << JOBCTL_TRAP_STOP_BIT) #define JOBCTL_TRAP_NOTIFY (1 << JOBCTL_TRAP_NOTIFY_BIT) #define JOBCTL_TRAPPING (1 << JOBCTL_TRAPPING_BIT) +#define JOBCTL_LISTENING (1 << JOBCTL_LISTENING_BIT) #define JOBCTL_TRAP_MASK (JOBCTL_TRAP_STOP | JOBCTL_TRAP_NOTIFY) #define JOBCTL_PENDING_MASK (JOBCTL_STOP_PENDING | JOBCTL_TRAP_MASK) diff --git a/kernel/exit.c b/kernel/exit.c index 20a406471525..289f59d686bf 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1368,7 +1368,8 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) static int *task_stopped_code(struct task_struct *p, bool ptrace) { if (ptrace) { - if (task_is_stopped_or_traced(p)) + if (task_is_stopped_or_traced(p) && + !(p->jobctl & JOBCTL_LISTENING)) return &p->exit_code; } else { if (p->signal->flags & SIGNAL_STOP_STOPPED) diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 6852c0f4a916..e18966c1c0da 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -146,7 +146,8 @@ int ptrace_check_attach(struct task_struct *child, bool ignore_state) */ spin_lock_irq(&child->sighand->siglock); WARN_ON_ONCE(task_is_stopped(child)); - if (task_is_traced(child) || ignore_state) + if (ignore_state || (task_is_traced(child) && + !(child->jobctl & JOBCTL_LISTENING))) ret = 0; spin_unlock_irq(&child->sighand->siglock); } @@ -660,7 +661,7 @@ int ptrace_request(struct task_struct *child, long request, { bool seized = child->ptrace & PT_SEIZED; int ret = -EIO; - siginfo_t siginfo; + siginfo_t siginfo, *si; void __user *datavp = (void __user *) data; unsigned long __user *datalp = datavp; unsigned long flags; @@ -710,8 +711,43 @@ int ptrace_request(struct task_struct *child, long request, if (unlikely(!seized || !lock_task_sighand(child, &flags))) break; + /* + * INTERRUPT doesn't disturb existing trap sans one + * exception. If ptracer issued LISTEN for the current + * STOP, this INTERRUPT should clear LISTEN and re-trap + * tracee into STOP. + */ if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP))) - signal_wake_up(child, 0); + signal_wake_up(child, child->jobctl & JOBCTL_LISTENING); + + unlock_task_sighand(child, &flags); + ret = 0; + break; + + case PTRACE_LISTEN: + /* + * Listen for events. Tracee must be in STOP. It's not + * resumed per-se but is not considered to be in TRACED by + * wait(2) or ptrace(2). If an async event (e.g. group + * stop state change) happens, tracee will enter STOP trap + * again. Alternatively, ptracer can issue INTERRUPT to + * finish listening and re-trap tracee into STOP. + */ + if (unlikely(!seized || !lock_task_sighand(child, &flags))) + break; + + si = child->last_siginfo; + if (unlikely(!si || si->si_code >> 8 != PTRACE_EVENT_STOP)) + break; + + child->jobctl |= JOBCTL_LISTENING; + + /* + * If NOTIFY is set, it means event happened between start + * of this trap and now. Trigger re-trap immediately. + */ + if (child->jobctl & JOBCTL_TRAP_NOTIFY) + signal_wake_up(child, true); unlock_task_sighand(child, &flags); ret = 0; diff --git a/kernel/signal.c b/kernel/signal.c index 06177e2b3917..97e575a3387e 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -825,9 +825,11 @@ static int check_kill_permission(int sig, struct siginfo *info, * TRAP_STOP to notify ptracer of an event. @t must have been seized by * ptracer. * - * If @t is running, STOP trap will be taken. If already trapped, STOP - * trap will be eventually taken without returning to userland after the - * existing traps are finished by PTRACE_CONT. + * If @t is running, STOP trap will be taken. If trapped for STOP and + * ptracer is listening for events, tracee is woken up so that it can + * re-trap for the new event. If trapped otherwise, STOP trap will be + * eventually taken without returning to userland after the existing traps + * are finished by PTRACE_CONT. * * CONTEXT: * Must be called with @task->sighand->siglock held. @@ -838,7 +840,7 @@ static void ptrace_trap_notify(struct task_struct *t) assert_spin_locked(&t->sighand->siglock); task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY); - signal_wake_up(t, 0); + signal_wake_up(t, t->jobctl & JOBCTL_LISTENING); } /* @@ -1894,6 +1896,9 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info) spin_lock_irq(¤t->sighand->siglock); current->last_siginfo = NULL; + /* LISTENING can be set only during STOP traps, clear it */ + current->jobctl &= ~JOBCTL_LISTENING; + /* * Queued signals ignored us while we were stopped for tracing. * So check for any that we should take before resuming user mode. |