2 files changed, 92 insertions, 0 deletions

diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h
index 022ab186a812..52ebcc89f306 100644
--- a/include/uapi/linux/ptrace.h
+++ b/include/uapi/linux/ptrace.h
@@ -5,6 +5,7 @@
 
 /* has the defines to get at the registers. */
 
+#include <linux/types.h>
 
 #define PTRACE_TRACEME             0
 #define PTRACE_PEEKTEXT            1
@@ -52,6 +53,17 @@
 #define PTRACE_INTERRUPT        0x4207
 #define PTRACE_LISTEN           0x4208
 
+#define PTRACE_PEEKSIGINFO      0x4209
+
+struct ptrace_peeksiginfo_args {
+        __u64 off;      /* from which siginfo to start */
+        __u32 flags;
+        __s32 nr;       /* how may siginfos to take */
+};
+
+/* Read signals from a shared (process wide) queue */
+#define PTRACE_PEEKSIGINFO_SHARED       (1 << 0)
+
 /* Wait extended result codes for the above trace options.  */
 #define PTRACE_EVENT_FORK       1
 #define PTRACE_EVENT_VFORK      2
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index acbd28424d81..17ae54da0ec2 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -24,6 +24,7 @@
 #include <linux/regset.h>
 #include <linux/hw_breakpoint.h>
 #include <linux/cn_proc.h>
+#include <linux/compat.h>
 
 
 static int ptrace_trapping_sleep_fn(void *flags)
@@ -618,6 +619,81 @@ static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
         return error;
 }
 
+static int ptrace_peek_siginfo(struct task_struct *child,
+                                unsigned long addr,
+                                unsigned long data)
+{
+        struct ptrace_peeksiginfo_args arg;
+        struct sigpending *pending;
+        struct sigqueue *q;
+        int ret, i;
+
+        ret = copy_from_user(&arg, (void __user *) addr,
+                                sizeof(struct ptrace_peeksiginfo_args));
+        if (ret)
+                return -EFAULT;
+
+        if (arg.flags & ~PTRACE_PEEKSIGINFO_SHARED)
+                return -EINVAL; /* unknown flags */
+
+        if (arg.nr < 0)
+                return -EINVAL;
+
+        if (arg.flags & PTRACE_PEEKSIGINFO_SHARED)
+                pending = &child->signal->shared_pending;
+        else
+                pending = &child->pending;
+
+        for (i = 0; i < arg.nr; ) {
+                siginfo_t info;
+                s32 off = arg.off + i;
+
+                spin_lock_irq(&child->sighand->siglock);
+                list_for_each_entry(q, &pending->list, list) {
+                        if (!off--) {
+                                copy_siginfo(&info, &q->info);
+                                break;
+                        }
+                }
+                spin_unlock_irq(&child->sighand->siglock);
+
+                if (off >= 0) /* beyond the end of the list */
+                        break;
+
+#ifdef CONFIG_COMPAT
+                if (unlikely(is_compat_task())) {
+                        compat_siginfo_t __user *uinfo = compat_ptr(data);
+
+                        ret = copy_siginfo_to_user32(uinfo, &info);
+                        ret |= __put_user(info.si_code, &uinfo->si_code);
+                } else
+#endif
+                {
+                        siginfo_t __user *uinfo = (siginfo_t __user *) data;
+
+                        ret = copy_siginfo_to_user(uinfo, &info);
+                        ret |= __put_user(info.si_code, &uinfo->si_code);
+                }
+
+                if (ret) {
+                        ret = -EFAULT;
+                        break;
+                }
+
+                data += sizeof(siginfo_t);
+                i++;
+
+                if (signal_pending(current))
+                        break;
+
+                cond_resched();
+        }
+
+        if (i > 0)
+                return i;
+
+        return ret;
+}
 
 #ifdef PTRACE_SINGLESTEP
 #define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
@@ -748,6 +824,10 @@ int ptrace_request(struct task_struct *child, long request,
                 ret = put_user(child->ptrace_message, datalp);
                 break;
 
+        case PTRACE_PEEKSIGINFO:
+                ret = ptrace_peek_siginfo(child, addr, data);
+                break;
+
         case PTRACE_GETSIGINFO:
                 ret = ptrace_getsiginfo(child, &siginfo);
                 if (!ret)