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Commit 0ba53597 authored by Elliott Hughes's avatar Elliott Hughes
Browse files

Better seccomp/kuser_helper diagnostics from debuggerd. 

Also switch to Android.bp for crasher.

Bug: http://b/34629282 (seccomp)
Bug: http://b/34705831 (seccomp)
Bug: http://b/34884086 (kuser_helpers)
Test: manual
Change-Id: I8ee79c635518faeba751742919af69a505b5e3e1
parent afe25958

debuggerd/Android.bp

+4 −0
Original line number Diff line number Diff line
@@ -195,3 +195,7 @@ cc_binary { 


    init_rc: ["tombstoned/tombstoned.rc"]

}



subdirs = [

    "crasher",

]

debuggerd/crasher/Android.bp

0 → 100644
+81 −0
Original line number Diff line number Diff line 
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",

        },

    },

}

debuggerd/crasher/Android.mk

deleted100644 → 0
+0 −66
Original line number Diff line number Diff line 
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)

debuggerd/crasher/crasher.cpp

+42 −1
Original line number Diff line number Diff line
@@ -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();

    }

debuggerd/libdebuggerd/tombstone.cpp

+37 −11
Original line number Diff line number Diff line
@@ -49,6 +49,8 @@ 
#include "open_files_list.h"

#include "tombstone.h"



using android::base::StringPrintf;



#define STACK_WORDS 16



#define MAX_TOMBSTONES  10
@@ -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",

  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());

  }