From: Oleg Nesterov <oleg@redhat.com>
[PATCH] signals: check ->group_stop_count after tracehook_get_signal()
Move the call to do_signal_stop() down, after tracehook call.
This makes ->group_stop_count condition visible to tracers before
do_signal_stop() will participate in this group-stop.
Currently the patch has no effect, tracehook_get_signal() always
returns 0.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Roland McGrath <roland@redhat.com>
---
arch/powerpc/include/asm/ptrace.h | 2 +
arch/powerpc/kernel/traps.c | 9 ++++++
arch/s390/kernel/traps.c | 6 ++--
arch/x86/include/asm/ptrace.h | 2 +
arch/x86/kernel/ptrace.c | 51 ++++++++++++++++++++----------------
include/linux/ptrace.h | 24 +++++++++++------
include/linux/sched.h | 1 +
include/linux/tracehook.h | 15 ++++++++---
kernel/ptrace.c | 2 +-
kernel/signal.c | 13 ++++-----
10 files changed, 79 insertions(+), 46 deletions(-)
diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 8c34149..cbd759e 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -140,6 +140,8 @@ extern void user_enable_single_step(stru
extern void user_enable_block_step(struct task_struct *);
extern void user_disable_single_step(struct task_struct *);
+#define ARCH_HAS_USER_SINGLE_STEP_INFO
+
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 6f0ae1a..83b57ac 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -174,6 +174,15 @@ int die(const char *str, struct pt_regs
return 0;
}
+void user_single_step_siginfo(struct task_struct *tsk,
+ struct pt_regs *regs, siginfo_t *info)
+{
+ memset(info, 0, sizeof(*info));
+ info->si_signo = SIGTRAP;
+ info->si_code = TRAP_TRACE;
+ info->si_addr = (void __user *)regs->nip;
+}
+
void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
{
siginfo_t info;
diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
index c2e42cc..6e7ad63 100644
--- a/arch/s390/kernel/traps.c
+++ b/arch/s390/kernel/traps.c
@@ -18,7 +18,7 @@
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
-#include <linux/ptrace.h>
+#include <linux/tracehook.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/smp.h>
@@ -382,7 +382,7 @@ void __kprobes do_single_step(struct pt_
SIGTRAP) == NOTIFY_STOP){
return;
}
- if ((current->ptrace & PT_PTRACED) != 0)
+ if (tracehook_consider_fatal_signal(current, SIGTRAP))
force_sig(SIGTRAP, current);
}
@@ -483,7 +483,7 @@ static void illegal_op(struct pt_regs *
if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
return;
if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
- if (current->ptrace & PT_PTRACED)
+ if (tracehook_consider_fatal_signal(current, SIGTRAP))
force_sig(SIGTRAP, current);
else
signal = SIGILL;
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 0f0d908..7a88a82 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -230,6 +230,8 @@ extern void user_enable_block_step(struc
#define arch_has_block_step() (boot_cpu_data.x86 >= 6)
#endif
+#define ARCH_HAS_USER_SINGLE_STEP_INFO
+
struct user_desc;
extern int do_get_thread_area(struct task_struct *p, int idx,
struct user_desc __user *info);
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 7b058a2..ea35dee 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -1437,21 +1437,33 @@ const struct user_regset_view *task_user
#endif
}
-void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
- int error_code, int si_code)
+static void fill_sigtrap_info(struct task_struct *tsk,
+ struct pt_regs *regs,
+ int error_code, int si_code,
+ struct siginfo *info)
{
- struct siginfo info;
-
tsk->thread.trap_no = 1;
tsk->thread.error_code = error_code;
- memset(&info, 0, sizeof(info));
- info.si_signo = SIGTRAP;
- info.si_code = si_code;
+ memset(info, 0, sizeof(*info));
+ info->si_signo = SIGTRAP;
+ info->si_code = si_code;
+ info->si_addr = user_mode_vm(regs) ? (void __user *)regs->ip : NULL;
+}
- /* User-mode ip? */
- info.si_addr = user_mode_vm(regs) ? (void __user *) regs->ip : NULL;
+void user_single_step_siginfo(struct task_struct *tsk,
+ struct pt_regs *regs,
+ struct siginfo *info)
+{
+ fill_sigtrap_info(tsk, regs, 0, TRAP_BRKPT, info);
+}
+
+void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
+ int error_code, int si_code)
+{
+ struct siginfo info;
+ fill_sigtrap_info(tsk, regs, error_code, si_code, &info);
/* Send us the fake SIGTRAP */
force_sig_info(SIGTRAP, &info, tsk);
}
@@ -1516,29 +1528,22 @@ asmregparm long syscall_trace_enter(stru
asmregparm void syscall_trace_leave(struct pt_regs *regs)
{
+ bool step;
+
if (unlikely(current->audit_context))
audit_syscall_exit(AUDITSC_RESULT(regs->ax), regs->ax);
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
trace_sys_exit(regs, regs->ax);
- if (test_thread_flag(TIF_SYSCALL_TRACE))
- tracehook_report_syscall_exit(regs, 0);
-
/*
* If TIF_SYSCALL_EMU is set, we only get here because of
* TIF_SINGLESTEP (i.e. this is PTRACE_SYSEMU_SINGLESTEP).
* We already reported this syscall instruction in
- * syscall_trace_enter(), so don't do any more now.
- */
- if (unlikely(test_thread_flag(TIF_SYSCALL_EMU)))
- return;
-
- /*
- * If we are single-stepping, synthesize a trap to follow the
- * system call instruction.
+ * syscall_trace_enter().
*/
- if (test_thread_flag(TIF_SINGLESTEP) &&
- tracehook_consider_fatal_signal(current, SIGTRAP))
- send_sigtrap(current, regs, 0, TRAP_BRKPT);
+ step = unlikely(test_thread_flag(TIF_SINGLESTEP)) &&
+ !test_thread_flag(TIF_SYSCALL_EMU);
+ if (step || test_thread_flag(TIF_SYSCALL_TRACE))
+ tracehook_report_syscall_exit(regs, step);
}
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index 7456d7d..4802e2a 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -85,6 +85,7 @@ extern int ptrace_traceme(void);
extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
extern int ptrace_attach(struct task_struct *tsk);
+extern bool __ptrace_detach(struct task_struct *tracer, struct task_struct *tracee);
extern int ptrace_detach(struct task_struct *, unsigned int);
extern void ptrace_disable(struct task_struct *);
extern int ptrace_check_attach(struct task_struct *task, int kill);
@@ -105,12 +106,7 @@ static inline int ptrace_reparented(stru
{
return child->real_parent != child->parent;
}
-static inline void ptrace_link(struct task_struct *child,
- struct task_struct *new_parent)
-{
- if (unlikely(child->ptrace))
- __ptrace_link(child, new_parent);
-}
+
static inline void ptrace_unlink(struct task_struct *child)
{
if (unlikely(child->ptrace))
@@ -169,9 +165,9 @@ static inline void ptrace_init_task(stru
INIT_LIST_HEAD(&child->ptraced);
child->parent = child->real_parent;
child->ptrace = 0;
- if (unlikely(ptrace)) {
+ if (unlikely(ptrace) && (current->ptrace & PT_PTRACED)) {
child->ptrace = current->ptrace;
- ptrace_link(child, current->parent);
+ __ptrace_link(child, current->parent);
}
}
@@ -278,6 +274,18 @@ static inline void user_enable_block_ste
}
#endif /* arch_has_block_step */
+#ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
+extern void user_single_step_siginfo(struct task_struct *tsk,
+ struct pt_regs *regs, siginfo_t *info);
+#else
+static inline void user_single_step_siginfo(struct task_struct *tsk,
+ struct pt_regs *regs, siginfo_t *info)
+{
+ memset(info, 0, sizeof(*info));
+ info->si_signo = SIGTRAP;
+}
+#endif
+
#ifndef arch_ptrace_stop_needed
/**
* arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 75e6e60..6c8928b 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2060,6 +2060,7 @@ extern int kill_pgrp(struct pid *pid, in
extern int kill_pid(struct pid *pid, int sig, int priv);
extern int kill_proc_info(int, struct siginfo *, pid_t);
extern int do_notify_parent(struct task_struct *, int);
+extern void do_notify_parent_cldstop(struct task_struct *, int);
extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
extern void force_sig(int, struct task_struct *);
extern void force_sig_specific(int, struct task_struct *);
diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index 1eb44a9..c78b2f4 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -134,6 +134,13 @@ static inline __must_check int tracehook
*/
static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step)
{
+ if (step && (task_ptrace(current) & PT_PTRACED)) {
+ siginfo_t info;
+ user_single_step_siginfo(current, regs, &info);
+ force_sig_info(SIGTRAP, &info, current);
+ return;
+ }
+
ptrace_report_syscall(regs);
}
@@ -149,7 +156,7 @@ static inline int tracehook_unsafe_exec(
{
int unsafe = 0;
int ptrace = task_ptrace(task);
- if (ptrace & PT_PTRACED) {
+ if (ptrace) {
if (ptrace & PT_PTRACE_CAP)
unsafe |= LSM_UNSAFE_PTRACE_CAP;
else
@@ -171,7 +178,7 @@ static inline int tracehook_unsafe_exec(
*/
static inline struct task_struct *tracehook_tracer_task(struct task_struct *tsk)
{
- if (task_ptrace(tsk) & PT_PTRACED)
+ if (task_ptrace(tsk))
return rcu_dereference(tsk->parent);
return NULL;
}
@@ -379,7 +386,7 @@ static inline void tracehook_signal_hand
const struct k_sigaction *ka,
struct pt_regs *regs, int stepping)
{
- if (stepping)
+ if (stepping && (task_ptrace(current) & PT_PTRACED))
ptrace_notify(SIGTRAP);
}
@@ -485,7 +492,7 @@ static inline int tracehook_get_signal(s
*/
static inline int tracehook_notify_jctl(int notify, int why)
{
- return notify ?: (current->ptrace & PT_PTRACED) ? why : 0;
+ return notify ?: task_ptrace(current) ? why : 0;
}
/**
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 23bd09c..b7c1d32 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -271,7 +271,7 @@ static int ignoring_children(struct sigh
* reap it now, in that case we must also wake up sub-threads sleeping in
* do_wait().
*/
-static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
+bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
{
__ptrace_unlink(p);
diff --git a/kernel/signal.c b/kernel/signal.c
index 6705320..9908335 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1461,7 +1461,7 @@ int do_notify_parent(struct task_struct
return ret;
}
-static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
+void do_notify_parent_cldstop(struct task_struct *tsk, int why)
{
struct siginfo info;
unsigned long flags;
@@ -1731,7 +1731,7 @@ static int do_signal_stop(int signr)
static int ptrace_signal(int signr, siginfo_t *info,
struct pt_regs *regs, void *cookie)
{
- if (!task_ptrace(current))
+ if (!(task_ptrace(current) & PT_PTRACED))
return signr;
ptrace_signal_deliver(regs, cookie);
@@ -1807,11 +1807,6 @@ relock:
for (;;) {
struct k_sigaction *ka;
-
- if (unlikely(signal->group_stop_count > 0) &&
- do_signal_stop(0))
- goto relock;
-
/*
* Tracing can induce an artifical signal and choose sigaction.
* The return value in @signr determines the default action,
@@ -1823,6 +1818,10 @@ relock:
if (unlikely(signr != 0))
ka = return_ka;
else {
+ if (unlikely(signal->group_stop_count > 0) &&
+ do_signal_stop(0))
+ goto relock;
+
signr = dequeue_signal(current, ¤t->blocked,
info);