1 files changed, 100 insertions, 1 deletions

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 83a531cea2f3..cb9ddcc08119 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -32,6 +32,8 @@
 #include <linux/compat.h>
 #include <linux/sched/signal.h>
 
+#include <asm/syscall.h>        /* for syscall_get_* */
+
 /*
  * Access another process' address space via ptrace.
  * Source/target buffer must be kernel space,
@@ -897,7 +899,100 @@ static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
  * to ensure no machine forgets it.
  */
 EXPORT_SYMBOL_GPL(task_user_regset_view);
-#endif
+
+static unsigned long
+ptrace_get_syscall_info_entry(struct task_struct *child, struct pt_regs *regs,
+                              struct ptrace_syscall_info *info)
+{
+        unsigned long args[ARRAY_SIZE(info->entry.args)];
+        int i;
+
+        info->op = PTRACE_SYSCALL_INFO_ENTRY;
+        info->entry.nr = syscall_get_nr(child, regs);
+        syscall_get_arguments(child, regs, args);
+        for (i = 0; i < ARRAY_SIZE(args); i++)
+                info->entry.args[i] = args[i];
+
+        /* args is the last field in struct ptrace_syscall_info.entry */
+        return offsetofend(struct ptrace_syscall_info, entry.args);
+}
+
+static unsigned long
+ptrace_get_syscall_info_seccomp(struct task_struct *child, struct pt_regs *regs,
+                                struct ptrace_syscall_info *info)
+{
+        /*
+         * As struct ptrace_syscall_info.entry is currently a subset
+         * of struct ptrace_syscall_info.seccomp, it makes sense to
+         * initialize that subset using ptrace_get_syscall_info_entry().
+         * This can be reconsidered in the future if these structures
+         * diverge significantly enough.
+         */
+        ptrace_get_syscall_info_entry(child, regs, info);
+        info->op = PTRACE_SYSCALL_INFO_SECCOMP;
+        info->seccomp.ret_data = child->ptrace_message;
+
+        /* ret_data is the last field in struct ptrace_syscall_info.seccomp */
+        return offsetofend(struct ptrace_syscall_info, seccomp.ret_data);
+}
+
+static unsigned long
+ptrace_get_syscall_info_exit(struct task_struct *child, struct pt_regs *regs,
+                             struct ptrace_syscall_info *info)
+{
+        info->op = PTRACE_SYSCALL_INFO_EXIT;
+        info->exit.rval = syscall_get_error(child, regs);
+        info->exit.is_error = !!info->exit.rval;
+        if (!info->exit.is_error)
+                info->exit.rval = syscall_get_return_value(child, regs);
+
+        /* is_error is the last field in struct ptrace_syscall_info.exit */
+        return offsetofend(struct ptrace_syscall_info, exit.is_error);
+}
+
+static int
+ptrace_get_syscall_info(struct task_struct *child, unsigned long user_size,
+                        void __user *datavp)
+{
+        struct pt_regs *regs = task_pt_regs(child);
+        struct ptrace_syscall_info info = {
+                .op = PTRACE_SYSCALL_INFO_NONE,
+                .arch = syscall_get_arch(child),
+                .instruction_pointer = instruction_pointer(regs),
+                .stack_pointer = user_stack_pointer(regs),
+        };
+        unsigned long actual_size = offsetof(struct ptrace_syscall_info, entry);
+        unsigned long write_size;
+
+        /*
+         * This does not need lock_task_sighand() to access
+         * child->last_siginfo because ptrace_freeze_traced()
+         * called earlier by ptrace_check_attach() ensures that
+         * the tracee cannot go away and clear its last_siginfo.
+         */
+        switch (child->last_siginfo ? child->last_siginfo->si_code : 0) {
+        case SIGTRAP | 0x80:
+                switch (child->ptrace_message) {
+                case PTRACE_EVENTMSG_SYSCALL_ENTRY:
+                        actual_size = ptrace_get_syscall_info_entry(child, regs,
+                                                                    &info);
+                        break;
+                case PTRACE_EVENTMSG_SYSCALL_EXIT:
+                        actual_size = ptrace_get_syscall_info_exit(child, regs,
+                                                                   &info);
+                        break;
+                }
+                break;
+        case SIGTRAP | (PTRACE_EVENT_SECCOMP << 8):
+                actual_size = ptrace_get_syscall_info_seccomp(child, regs,
+                                                              &info);
+                break;
+        }
+
+        write_size = min(actual_size, user_size);
+        return copy_to_user(datavp, &info, write_size) ? -EFAULT : actual_size;
+}
+#endif /* CONFIG_HAVE_ARCH_TRACEHOOK */
 
 int ptrace_request(struct task_struct *child, long request,
                    unsigned long addr, unsigned long data)
@@ -1114,6 +1209,10 @@ int ptrace_request(struct task_struct *child, long request,
                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
                 break;
         }
+
+        case PTRACE_GET_SYSCALL_INFO:
+                ret = ptrace_get_syscall_info(child, addr, datavp);
+                break;
 #endif
 
         case PTRACE_SECCOMP_GET_FILTER: