Merge "Better seccomp/kuser_helper diagnostics from debuggerd."

5 files changed, 164 insertions, 78 deletions

diff --git a/debuggerd/Android.bp b/debuggerd/Android.bp
index 6dc6675ac..ca881aaf0 100644
--- a/debuggerd/Android.bp
+++ b/debuggerd/Android.bp
@@ -195,3 +195,7 @@ cc_binary {
 
     init_rc: ["tombstoned/tombstoned.rc"]
 }
+
+subdirs = [
+    "crasher",
+]
diff --git a/debuggerd/crasher/Android.bp b/debuggerd/crasher/Android.bp
new file mode 100644
index 000000000..47278940e
--- /dev/null
+++ b/debuggerd/crasher/Android.bp
@@ -0,0 +1,81 @@
+cc_defaults {
+    name: "crasher-defaults",
+
+    cppflags: [
+        "-std=gnu++14",
+        "-W",
+        "-Wall",
+        "-Wextra",
+        "-Wunused",
+        "-Werror",
+        "-O0",
+        "-fstack-protector-all",
+        "-Wno-free-nonheap-object",
+        "-Wno-date-time",
+    ],
+    srcs: ["crasher.cpp"],
+    arch: {
+        arm: {
+            srcs: ["arm/crashglue.S"],
+
+            armv7_a_neon: {
+                asflags: ["-DHAS_VFP_D32"],
+            },
+        },
+        arm64: {
+            srcs: ["arm64/crashglue.S"],
+        },
+        mips: {
+            srcs: ["mips/crashglue.S"],
+        },
+        mips64: {
+            srcs: ["mips64/crashglue.S"],
+        },
+        x86: {
+            srcs: ["x86/crashglue.S"],
+        },
+        x86_64: {
+            srcs: ["x86_64/crashglue.S"],
+        },
+    },
+    compile_multilib: "both",
+}
+
+cc_binary {
+    name: "crasher",
+
+    defaults: ["crasher-defaults"],
+    shared_libs: [
+        "libbase",
+        "liblog",
+    ],
+    multilib: {
+        lib32: {
+            stem: "crasher",
+        },
+        lib64: {
+            stem: "crasher64",
+        },
+    },
+}
+
+cc_binary {
+    name: "static_crasher",
+
+    defaults: ["crasher-defaults"],
+    cppflags: ["-DSTATIC_CRASHER"],
+    static_executable: true,
+    static_libs: [
+        "libdebuggerd_handler",
+        "libbase",
+        "liblog",
+    ],
+    multilib: {
+        lib32: {
+            stem: "static_crasher",
+        },
+        lib64: {
+            stem: "static_crasher64",
+        },
+    },
+}
diff --git a/debuggerd/crasher/Android.mk b/debuggerd/crasher/Android.mk
deleted file mode 100644
index b8b786be0..000000000
--- a/debuggerd/crasher/Android.mk
+++ /dev/null
@@ -1,66 +0,0 @@
-LOCAL_PATH := $(call my-dir)
-
-crasher_cppflags := \
-    -std=gnu++14 \
-    -W \
-    -Wall \
-    -Wextra \
-    -Wunused \
-    -Werror \
-    -O0 \
-    -fstack-protector-all \
-    -Wno-free-nonheap-object \
-    -Wno-date-time
-
-include $(CLEAR_VARS)
-LOCAL_SRC_FILES := crasher.cpp
-LOCAL_SRC_FILES_arm    := arm/crashglue.S
-LOCAL_SRC_FILES_arm64  := arm64/crashglue.S
-LOCAL_SRC_FILES_mips   := mips/crashglue.S
-LOCAL_SRC_FILES_mips64 := mips64/crashglue.S
-LOCAL_SRC_FILES_x86    := x86/crashglue.S
-LOCAL_SRC_FILES_x86_64 := x86_64/crashglue.S
-LOCAL_MODULE_PATH := $(TARGET_OUT_OPTIONAL_EXECUTABLES)
-LOCAL_MODULE_TAGS := optional
-LOCAL_CPPFLAGS := $(crasher_cppflags)
-LOCAL_SHARED_LIBRARIES := libbase liblog
-
-# The arm emulator has VFP but not VFPv3-D32.
-ifeq ($(ARCH_ARM_HAVE_VFP_D32),true)
-LOCAL_ASFLAGS_arm += -DHAS_VFP_D32
-endif
-
-LOCAL_MODULE := crasher
-LOCAL_MODULE_STEM_32 := crasher
-LOCAL_MODULE_STEM_64 := crasher64
-LOCAL_MULTILIB := both
-
-include $(BUILD_EXECUTABLE)
-
-include $(CLEAR_VARS)
-LOCAL_SRC_FILES := crasher.cpp
-LOCAL_SRC_FILES_arm    := arm/crashglue.S
-LOCAL_SRC_FILES_arm64  := arm64/crashglue.S
-LOCAL_SRC_FILES_mips   := mips/crashglue.S
-LOCAL_SRC_FILES_mips64 := mips64/crashglue.S
-LOCAL_SRC_FILES_x86    := x86/crashglue.S
-LOCAL_SRC_FILES_x86_64 := x86_64/crashglue.S
-LOCAL_MODULE_PATH := $(TARGET_OUT_OPTIONAL_EXECUTABLES)
-LOCAL_MODULE_TAGS := optional
-LOCAL_CPPFLAGS := $(crasher_cppflags) -DSTATIC_CRASHER
-LOCAL_FORCE_STATIC_EXECUTABLE := true
-LOCAL_SHARED_LIBRARIES := libbase liblog
-
-# The arm emulator has VFP but not VFPv3-D32.
-ifeq ($(ARCH_ARM_HAVE_VFP_D32),true)
-LOCAL_ASFLAGS_arm += -DHAS_VFP_D32
-endif
-
-LOCAL_MODULE := static_crasher
-LOCAL_MODULE_STEM_32 := static_crasher
-LOCAL_MODULE_STEM_64 := static_crasher64
-LOCAL_MULTILIB := both
-
-LOCAL_STATIC_LIBRARIES := libdebuggerd_handler libbase liblog
-
-include $(BUILD_EXECUTABLE)
diff --git a/debuggerd/crasher/crasher.cpp b/debuggerd/crasher/crasher.cpp
index 288f1165e..64a38dd8c 100644
--- a/debuggerd/crasher/crasher.cpp
+++ b/debuggerd/crasher/crasher.cpp
@@ -36,6 +36,19 @@
 #include "debuggerd/handler.h"
 #endif
 
+#if defined(__arm__)
+// See https://www.kernel.org/doc/Documentation/arm/kernel_user_helpers.txt for details.
+#define __kuser_helper_version (*(int32_t*) 0xffff0ffc)
+typedef void * (__kuser_get_tls_t)(void);
+#define __kuser_get_tls (*(__kuser_get_tls_t*) 0xffff0fe0)
+typedef int (__kuser_cmpxchg_t)(int oldval, int newval, volatile int *ptr);
+#define __kuser_cmpxchg (*(__kuser_cmpxchg_t*) 0xffff0fc0)
+typedef void (__kuser_dmb_t)(void);
+#define __kuser_dmb (*(__kuser_dmb_t*) 0xffff0fa0)
+typedef int (__kuser_cmpxchg64_t)(const int64_t*, const int64_t*, volatile int64_t*);
+#define __kuser_cmpxchg64 (*(__kuser_cmpxchg64_t*) 0xffff0f60)
+#endif
+
 #define noinline __attribute__((__noinline__))
 
 // Avoid name mangling so that stacks are more readable.
@@ -142,22 +155,36 @@ static int usage() {
     fprintf(stderr, "where KIND is:\n");
     fprintf(stderr, "  smash-stack           overwrite a -fstack-protector guard\n");
     fprintf(stderr, "  stack-overflow        recurse until the stack overflows\n");
+    fprintf(stderr, "  nostack               crash with a NULL stack pointer\n");
+    fprintf(stderr, "\n");
     fprintf(stderr, "  heap-corruption       cause a libc abort by corrupting the heap\n");
     fprintf(stderr, "  heap-usage            cause a libc abort by abusing a heap function\n");
-    fprintf(stderr, "  nostack               crash with a NULL stack pointer\n");
+    fprintf(stderr, "\n");
     fprintf(stderr, "  abort                 call abort()\n");
     fprintf(stderr, "  assert                call assert() without a function\n");
     fprintf(stderr, "  assert2               call assert() with a function\n");
     fprintf(stderr, "  exit                  call exit(1)\n");
+    fprintf(stderr, "\n");
     fprintf(stderr, "  fortify               fail a _FORTIFY_SOURCE check\n");
+    fprintf(stderr, "  seccomp               fail a seccomp check\n");
+#if defined(__arm__)
+    fprintf(stderr, "  kuser_helper_version  call kuser_helper_version\n");
+    fprintf(stderr, "  kuser_get_tls         call kuser_get_tls\n");
+    fprintf(stderr, "  kuser_cmpxchg         call kuser_cmpxchg\n");
+    fprintf(stderr, "  kuser_memory_barrier  call kuser_memory_barrier\n");
+    fprintf(stderr, "  kuser_cmpxchg64       call kuser_cmpxchg64\n");
+#endif
+    fprintf(stderr, "\n");
     fprintf(stderr, "  LOG_ALWAYS_FATAL      call liblog LOG_ALWAYS_FATAL\n");
     fprintf(stderr, "  LOG_ALWAYS_FATAL_IF   call liblog LOG_ALWAYS_FATAL_IF\n");
     fprintf(stderr, "  LOG-FATAL             call libbase LOG(FATAL)\n");
+    fprintf(stderr, "\n");
     fprintf(stderr, "  SIGFPE                cause a SIGFPE\n");
     fprintf(stderr, "  SIGSEGV               cause a SIGSEGV at address 0x0 (synonym: crash)\n");
     fprintf(stderr, "  SIGSEGV-non-null      cause a SIGSEGV at a non-zero address\n");
     fprintf(stderr, "  SIGSEGV-unmapped      mmap/munmap a region of memory and then attempt to access it\n");
     fprintf(stderr, "  SIGTRAP               cause a SIGTRAP\n");
+    fprintf(stderr, "\n");
     fprintf(stderr, "  fprintf-NULL          pass a null pointer to fprintf\n");
     fprintf(stderr, "  readdir-NULL          pass a null pointer to readdir\n");
     fprintf(stderr, "  strlen-NULL           pass a null pointer to strlen\n");
@@ -235,6 +262,20 @@ noinline int do_action(const char* arg) {
                                                  MAP_SHARED | MAP_ANONYMOUS, -1, 0));
         munmap(map, sizeof(int));
         map[0] = '8';
+    } else if (!strcasecmp(arg, "seccomp")) {
+        syscall(99999);
+#if defined(__arm__)
+    } else if (!strcasecmp(arg, "kuser_helper_version")) {
+        return __kuser_helper_version;
+    } else if (!strcasecmp(arg, "kuser_get_tls")) {
+        return !__kuser_get_tls();
+    } else if (!strcasecmp(arg, "kuser_cmpxchg")) {
+        return __kuser_cmpxchg(0, 0, 0);
+    } else if (!strcasecmp(arg, "kuser_memory_barrier")) {
+        __kuser_dmb();
+    } else if (!strcasecmp(arg, "kuser_cmpxchg64")) {
+        return __kuser_cmpxchg64(0, 0, 0);
+#endif
     } else {
         return usage();
     }
diff --git a/debuggerd/libdebuggerd/tombstone.cpp b/debuggerd/libdebuggerd/tombstone.cpp
index 01e9cf69b..ac2c0b6c4 100644
--- a/debuggerd/libdebuggerd/tombstone.cpp
+++ b/debuggerd/libdebuggerd/tombstone.cpp
@@ -49,6 +49,8 @@
 #include "open_files_list.h"
 #include "tombstone.h"
 
+using android::base::StringPrintf;
+
 #define STACK_WORDS 16
 
 #define MAX_TOMBSTONES  10
@@ -74,7 +76,7 @@ static bool signal_has_si_addr(int si_signo, int si_code) {
 }
 
 static const char* get_signame(int sig) {
-  switch(sig) {
+  switch (sig) {
     case SIGABRT: return "SIGABRT";
     case SIGBUS: return "SIGBUS";
     case SIGFPE: return "SIGFPE";
@@ -195,6 +197,29 @@ static void dump_header_info(log_t* log) {
   _LOG(log, logtype::HEADER, "ABI: '%s'\n", ABI_STRING);
 }
 
+static void dump_probable_cause(log_t* log, const siginfo_t& si) {
+  std::string cause;
+  if (si.si_signo == SIGSEGV && si.si_code == SEGV_MAPERR) {
+    if (si.si_addr < reinterpret_cast<void*>(4096)) {
+      cause = StringPrintf("null pointer dereference");
+    } else if (si.si_addr == reinterpret_cast<void*>(0xffff0ffc)) {
+      cause = "call to kuser_helper_version";
+    } else if (si.si_addr == reinterpret_cast<void*>(0xffff0fe0)) {
+      cause = "call to kuser_get_tls";
+    } else if (si.si_addr == reinterpret_cast<void*>(0xffff0fc0)) {
+      cause = "call to kuser_cmpxchg";
+    } else if (si.si_addr == reinterpret_cast<void*>(0xffff0fa0)) {
+      cause = "call to kuser_memory_barrier";
+    } else if (si.si_addr == reinterpret_cast<void*>(0xffff0f60)) {
+      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);
+  }
+
+  if (!cause.empty()) _LOG(log, logtype::HEADER, "Cause: %s\n", cause.c_str());
+}
+
 static void dump_signal_info(log_t* log, pid_t tid) {
   siginfo_t si;
   memset(&si, 0, sizeof(si));
@@ -212,6 +237,8 @@ static void dump_signal_info(log_t* log, pid_t tid) {
 
   _LOG(log, logtype::HEADER, "signal %d (%s), code %d (%s), fault addr %s\n", si.si_signo,
        get_signame(si.si_signo), si.si_code, get_sigcode(si.si_signo, si.si_code), addr_desc);
+
+  dump_probable_cause(log, si);
 }
 
 static void dump_thread_info(log_t* log, pid_t pid, pid_t tid) {
@@ -262,11 +289,11 @@ static void dump_stack_segment(
     line = "    ";
     if (i == 0 && label >= 0) {
       // Print the label once.
-      line += android::base::StringPrintf("#%02d  ", label);
+      line += StringPrintf("#%02d  ", label);
     } else {
       line += "     ";
     }
-    line += android::base::StringPrintf("%" PRIPTR "  %" PRIPTR, *sp, stack_data[i]);
+    line += StringPrintf("%" PRIPTR "  %" PRIPTR, *sp, stack_data[i]);
 
     backtrace_map_t map;
     backtrace->FillInMap(stack_data[i], &map);
@@ -277,7 +304,7 @@ static void dump_stack_segment(
       if (!func_name.empty()) {
         line += " (" + func_name;
         if (offset) {
-          line += android::base::StringPrintf("+%" PRIuPTR, offset);
+          line += StringPrintf("+%" PRIuPTR, offset);
         }
         line += ')';
       }
@@ -336,11 +363,11 @@ static void dump_stack(Backtrace* backtrace, log_t* log) {
 static std::string get_addr_string(uintptr_t addr) {
   std::string addr_str;
 #if defined(__LP64__)
-  addr_str = android::base::StringPrintf("%08x'%08x",
-                                         static_cast<uint32_t>(addr >> 32),
-                                         static_cast<uint32_t>(addr & 0xffffffff));
+  addr_str = StringPrintf("%08x'%08x",
+                          static_cast<uint32_t>(addr >> 32),
+                          static_cast<uint32_t>(addr & 0xffffffff));
 #else
-  addr_str = android::base::StringPrintf("%08x", addr);
+  addr_str = StringPrintf("%08x", addr);
 #endif
   return addr_str;
 }
@@ -426,8 +453,7 @@ static void dump_all_maps(Backtrace* backtrace, BacktraceMap* map, log_t* log, p
     } else {
       line += '-';
     }
-    line += android::base::StringPrintf("  %8" PRIxPTR "  %8" PRIxPTR,
-                                        it->offset, it->end - it->start);
+    line += StringPrintf("  %8" PRIxPTR "  %8" PRIxPTR, it->offset, it->end - it->start);
     bool space_needed = true;
     if (it->name.length() > 0) {
       space_needed = false;
@@ -441,7 +467,7 @@ static void dump_all_maps(Backtrace* backtrace, BacktraceMap* map, log_t* log, p
       if (space_needed) {
         line += ' ';
       }
-      line += android::base::StringPrintf(" (load base 0x%" PRIxPTR ")", it->load_base);
+      line += StringPrintf(" (load base 0x%" PRIxPTR ")", it->load_base);
     }
     _LOG(log, logtype::MAPS, "%s\n", line.c_str());
   }