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Commit 5fdc4cc7 authored by Jeff Vander Stoep's avatar Jeff Vander Stoep
Browse files

Revert "crash_dump: during early boot, output to kmsg on userdebug." 

This reverts commit bf2dd482.

Addresses:
avc: denied { relabelto } for name="kmsg_debug" dev="tmpfs" ino=10642
scontext=u:r:init:s0 tcontext=u:object_r:device:s0 tclass=chr_file

Bug: 62101480, 35197529
Test: build and boot device. Verify selinux denial no longer occurs.
Change-Id: I28ce16f50eec20ef15c1721f41b66f22a84e7cca
parent b7806433

debuggerd/libdebuggerd/utility.cpp

+1 −45
Original line number Diff line number Diff line
@@ -22,22 +22,16 @@ 
#include <signal.h>

#include <string.h>

#include <sys/ptrace.h>

#include <sys/uio.h>

#include <sys/wait.h>

#include <unistd.h>



#include <string>



#include <android-base/logging.h>

#include <android-base/properties.h>

#include <android-base/stringprintf.h>

#include <android-base/strings.h>

#include <android-base/unique_fd.h>

#include <backtrace/Backtrace.h>

#include <log/log.h>



using android::base::unique_fd;



// Whitelist output desired in the logcat output.

bool is_allowed_in_logcat(enum logtype ltype) {

  if ((ltype == HEADER)
@@ -48,19 +42,6 @@ bool is_allowed_in_logcat(enum logtype ltype) { 
  return false;

}



static bool should_write_to_kmsg() {

  // Write to kmsg if tombstoned isn't up, and we're able to do so.

  if (!android::base::GetBoolProperty("ro.debuggable", false)) {

    return false;

  }



  if (android::base::GetProperty("init.svc.tombstoned", "") == "running") {

    return false;

  }



  return true;

}



__attribute__((__weak__, visibility("default")))

void _LOG(log_t* log, enum logtype ltype, const char* fmt, ...) {

  bool write_to_tombstone = (log->tfd != -1);
@@ -68,7 +49,6 @@ void _LOG(log_t* log, enum logtype ltype, const char* fmt, ...) { 
                      && log->crashed_tid != -1

                      && log->current_tid != -1

                      && (log->crashed_tid == log->current_tid);

  static bool write_to_kmsg = should_write_to_kmsg();



  char buf[512];

  va_list ap;
@@ -90,30 +70,6 @@ void _LOG(log_t* log, enum logtype ltype, const char* fmt, ...) { 
    if (log->amfd_data != nullptr) {

      *log->amfd_data += buf;

    }



    if (write_to_kmsg) {

      unique_fd kmsg_fd(open("/dev/kmsg_debug", O_WRONLY | O_APPEND | O_CLOEXEC));

      if (kmsg_fd.get() >= 0) {

        // Our output might contain newlines which would otherwise be handled by the android logger.

        // Split the lines up ourselves before sending to the kernel logger.

        if (buf[len - 1] == '\n') {

          buf[len - 1] = '\0';

        }



        std::vector<std::string> fragments = android::base::Split(buf, "\n");

        for (const std::string& fragment : fragments) {

          static constexpr char prefix[] = "<3>DEBUG: ";

          struct iovec iov[3];

          iov[0].iov_base = const_cast<char*>(prefix);

          iov[0].iov_len = strlen(prefix);

          iov[1].iov_base = const_cast<char*>(fragment.c_str());

          iov[1].iov_len = fragment.length();

          iov[2].iov_base = const_cast<char*>("\n");

          iov[2].iov_len = 1;

          TEMP_FAILURE_RETRY(writev(kmsg_fd.get(), iov, 3));

        }

      }

    }

  }

}
@@ -249,7 +205,7 @@ void dump_memory(log_t* log, Backtrace* backtrace, uintptr_t addr, const char* f 
}



void read_with_default(const char* path, char* buf, size_t len, const char* default_value) {

  unique_fd fd(open(path, O_RDONLY | O_CLOEXEC));

  android::base::unique_fd fd(open(path, O_RDONLY));

  if (fd != -1) {

    int rc = TEMP_FAILURE_RETRY(read(fd.get(), buf, len - 1));

    if (rc != -1) {

init/Android.mk

+0 −2
Original line number Diff line number Diff line
@@ -9,14 +9,12 @@ init_options += \ 
    -DALLOW_LOCAL_PROP_OVERRIDE=1 \

    -DALLOW_PERMISSIVE_SELINUX=1 \

    -DREBOOT_BOOTLOADER_ON_PANIC=1 \

    -DWORLD_WRITABLE_KMSG=1 \

    -DDUMP_ON_UMOUNT_FAILURE=1

else

init_options += \

    -DALLOW_LOCAL_PROP_OVERRIDE=0 \

    -DALLOW_PERMISSIVE_SELINUX=0 \

    -DREBOOT_BOOTLOADER_ON_PANIC=0 \

    -DWORLD_WRITABLE_KMSG=0 \

    -DDUMP_ON_UMOUNT_FAILURE=0

endif

init/init.cpp

+0 −9
Original line number Diff line number Diff line
@@ -889,9 +889,6 @@ static void selinux_restore_context() { 
    LOG(INFO) << "Running restorecon...";

    selinux_android_restorecon("/dev", 0);

    selinux_android_restorecon("/dev/kmsg", 0);

    if constexpr (WORLD_WRITABLE_KMSG) {

        selinux_android_restorecon("/dev/kmsg_debug", 0);

    }

    selinux_android_restorecon("/dev/socket", 0);

    selinux_android_restorecon("/dev/random", 0);

    selinux_android_restorecon("/dev/urandom", 0);
@@ -997,13 +994,7 @@ int main(int argc, char** argv) { 
        setgroups(arraysize(groups), groups);

        mount("sysfs", "/sys", "sysfs", 0, NULL);

        mount("selinuxfs", "/sys/fs/selinux", "selinuxfs", 0, NULL);



        mknod("/dev/kmsg", S_IFCHR | 0600, makedev(1, 11));



        if constexpr (WORLD_WRITABLE_KMSG) {

          mknod("/dev/kmsg_debug", S_IFCHR | 0622, makedev(1, 11));

        }



        mknod("/dev/random", S_IFCHR | 0666, makedev(1, 8));

        mknod("/dev/urandom", S_IFCHR | 0666, makedev(1, 9));