[PATCH v3 4/6] ptrace: Track __TASK_TRACED state in p->ptrace
From: Peter Zijlstra <peterz@infradead.org>
Date: 2021-10-09 10:20:34
Also in:
lkml
Just like we can recover __TASK_STOPPED from p->jobctl, add some bits to p->ptrace such that we can recover __TASK_TRACED. All these t->ptrace modifications are done under sighand lock. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- include/linux/ptrace.h | 4 ++++ include/linux/sched/signal.h | 6 ++---- kernel/ptrace.c | 27 ++++++++++++++++++--------- kernel/signal.c | 1 + 4 files changed, 25 insertions(+), 13 deletions(-)
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h@@ -45,6 +45,10 @@ extern int ptrace_access_vm(struct task_ #define PT_TRACE_SECCOMP PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP) // 0x00000400 #define PT_SEIZED 0x00010000 /* SEIZE used, enable new behavior */// 0x00010000 +#define PT_STOPPED 0x00020000 // 0x00020000 +#define PT_STOPPED_FATAL 0x00040000 // 0x00040000 + +#define PT_STOPPED_MASK (PT_STOPPED|PT_STOPPED_FATAL) #define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT) // 0x00800000 #define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT) // 0x01000000 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h
@@ -418,10 +418,8 @@ static inline void signal_wake_up(struct { signal_wake_up_state(t, resume ? TASK_WAKEKILL : 0); } -static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume) -{ - signal_wake_up_state(t, resume ? __TASK_TRACED : 0); -} + +extern void ptrace_signal_wake_up(struct task_struct *t, bool resume); void task_join_group_stop(struct task_struct *task); --- a/kernel/ptrace.c +++ b/kernel/ptrace.c
@@ -64,6 +64,14 @@ int ptrace_access_vm(struct task_struct return ret; } +void ptrace_signal_wake_up(struct task_struct *t, bool resume) +{ + lockdep_assert_task_sighand_held(t); + + if (resume) + t->ptrace &= ~PT_STOPPED_MASK; + signal_wake_up_state(t, resume ? __TASK_TRACED : 0); +} void __ptrace_link(struct task_struct *child, struct task_struct *new_parent, const struct cred *ptracer_cred)
@@ -197,6 +205,8 @@ static bool ptrace_freeze_traced(struct spin_lock_irq(&task->sighand->siglock); if (task_is_traced(task) && !looks_like_a_spurious_pid(task) && !__fatal_signal_pending(task)) { + task->ptrace &= ~PT_STOPPED_MASK; + task->ptrace |= PT_STOPPED; WRITE_ONCE(task->__state, __TASK_TRACED); ret = true; }
@@ -218,10 +228,13 @@ static void ptrace_unfreeze_traced(struc */ spin_lock_irq(&task->sighand->siglock); if (READ_ONCE(task->__state) == __TASK_TRACED) { - if (__fatal_signal_pending(task)) + if (__fatal_signal_pending(task)) { + task->ptrace &= ~PT_STOPPED_MASK; wake_up_state(task, __TASK_TRACED); - else + } else { + task->ptrace |= PT_STOPPED_MASK; WRITE_ONCE(task->__state, TASK_TRACED); + } } spin_unlock_irq(&task->sighand->siglock); }
@@ -835,8 +848,6 @@ static long ptrace_get_rseq_configuratio static int ptrace_resume(struct task_struct *child, long request, unsigned long data) { - bool need_siglock; - if (!valid_signal(data)) return -EIO;
@@ -877,13 +888,11 @@ static int ptrace_resume(struct task_str * status and clears the code too; this can't race with the tracee, it * takes siglock after resume. */ - need_siglock = data && !thread_group_empty(current); - if (need_siglock) - spin_lock_irq(&child->sighand->siglock); + spin_lock_irq(&child->sighand->siglock); child->exit_code = data; + child->ptrace &= ~PT_STOPPED_MASK; wake_up_state(child, __TASK_TRACED); - if (need_siglock) - spin_unlock_irq(&child->sighand->siglock); + spin_unlock_irq(&child->sighand->siglock); return 0; } --- a/kernel/signal.c +++ b/kernel/signal.c
@@ -2228,6 +2228,7 @@ static void ptrace_stop(int exit_code, i return; } + current->ptrace |= PT_STOPPED_MASK; set_special_state(TASK_TRACED); /*