From 12b71294064e6dc0a225e19ce179e702f481d6a6 Mon Sep 17 00:00:00 2001
From: Elliott Hughes <enh@google.com>
Date: Thu, 2 Mar 2017 19:01:20 -0800
Subject: [PATCH] Small debuggerd improvements.

Include the ABI in seccomp causes.

Slightly improved command-line usage information.

Fix crasher for seccomp failures.

Bug: N/A
Test: crasher
Change-Id: Ie419ecfe72ee4f5ccf49c927be18350a58a66a90
---
 debuggerd/crasher/Android.bp         | 2 ++
 debuggerd/crasher/crasher.cpp        | 3 +++
 debuggerd/debuggerd.cpp              | 8 +++++---
 debuggerd/libdebuggerd/tombstone.cpp | 3 ++-
 4 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/debuggerd/crasher/Android.bp b/debuggerd/crasher/Android.bp
index 47278940e..f73f672fb 100644
--- a/debuggerd/crasher/Android.bp
+++ b/debuggerd/crasher/Android.bp
@@ -48,6 +48,7 @@ cc_binary {
     shared_libs: [
         "libbase",
         "liblog",
+        "libseccomp_policy",
     ],
     multilib: {
         lib32: {
@@ -69,6 +70,7 @@ cc_binary {
         "libdebuggerd_handler",
         "libbase",
         "liblog",
+        "libseccomp_policy",
     ],
     multilib: {
         lib32: {
diff --git a/debuggerd/crasher/crasher.cpp b/debuggerd/crasher/crasher.cpp
index 1c01e3ef5..697020171 100644
--- a/debuggerd/crasher/crasher.cpp
+++ b/debuggerd/crasher/crasher.cpp
@@ -33,6 +33,8 @@
 #include <android-base/logging.h>
 #include <log/log.h>
 
+#include "seccomp_policy.h"
+
 #if defined(STATIC_CRASHER)
 #include "debuggerd/handler.h"
 #endif
@@ -269,6 +271,7 @@ noinline int do_action(const char* arg) {
         munmap(map, sizeof(int));
         map[0] = '8';
     } else if (!strcasecmp(arg, "seccomp")) {
+        set_seccomp_filter();
         syscall(99999);
 #if defined(__arm__)
     } else if (!strcasecmp(arg, "kuser_helper_version")) {
diff --git a/debuggerd/debuggerd.cpp b/debuggerd/debuggerd.cpp
index 0c5d3cf9b..492e9f023 100644
--- a/debuggerd/debuggerd.cpp
+++ b/debuggerd/debuggerd.cpp
@@ -34,6 +34,8 @@ using android::base::unique_fd;
 
 static void usage(int exit_code) {
   fprintf(stderr, "usage: debuggerd [-b] PID\n");
+  fprintf(stderr, "\n");
+  fprintf(stderr, "-b, --backtrace    just a backtrace rather than a full tombstone\n");
   _exit(exit_code);
 }
 
@@ -56,7 +58,8 @@ static std::thread spawn_redirect_thread(unique_fd fd) {
 int main(int argc, char* argv[]) {
   if (argc <= 1) usage(0);
   if (argc > 3) usage(1);
-  if (argc == 3 && strcmp(argv[1], "-b") != 0) usage(1);
+  if (argc == 3 && strcmp(argv[1], "-b") != 0 && strcmp(argv[1], "--backtrace") != 0) usage(1);
+  bool backtrace_only = argc == 3;
 
   pid_t pid;
   if (!android::base::ParseInt(argv[argc - 1], &pid, 1, std::numeric_limits<pid_t>::max())) {
@@ -69,9 +72,8 @@ int main(int argc, char* argv[]) {
   }
 
   std::thread redirect_thread = spawn_redirect_thread(std::move(piperead));
-  bool backtrace = argc == 3;
   if (!debuggerd_trigger_dump(pid, std::move(pipewrite),
-                              backtrace ? kDebuggerdBacktrace : kDebuggerdTombstone, 0)) {
+                              backtrace_only ? kDebuggerdBacktrace : kDebuggerdTombstone, 0)) {
     redirect_thread.join();
     errx(1, "failed to dump process %d", pid);
   }
diff --git a/debuggerd/libdebuggerd/tombstone.cpp b/debuggerd/libdebuggerd/tombstone.cpp
index 3166bfc9d..4686bfdc8 100644
--- a/debuggerd/libdebuggerd/tombstone.cpp
+++ b/debuggerd/libdebuggerd/tombstone.cpp
@@ -214,7 +214,8 @@ static void dump_probable_cause(log_t* log, const siginfo_t& si) {
       cause = "call to kuser_cmpxchg64";
     }
   } else if (si.si_signo == SIGSYS && si.si_code == SYS_SECCOMP) {
-    cause = StringPrintf("seccomp prevented call to disallowed system call %d", si.si_syscall);
+    cause = StringPrintf("seccomp prevented call to disallowed %s system call %d",
+                         ABI_STRING, si.si_syscall);
   }
 
   if (!cause.empty()) _LOG(log, logtype::HEADER, "Cause: %s\n", cause.c_str());