This patch adds a new third-party library that implements an ELF dynamic linker.

third_party/crazy_linker/crazy_linker/tests/test_relro_sharing.cpp

Index: third_party/crazy_linker/crazy_linker/tests/test_relro_sharing.cpp
diff --git a/third_party/crazy_linker/crazy_linker/tests/test_relro_sharing.cpp b/third_party/crazy_linker/crazy_linker/tests/test_relro_sharing.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..85db97d98f02ae4dde8550db39698d71958ce064
--- /dev/null
+++ b/third_party/crazy_linker/crazy_linker/tests/test_relro_sharing.cpp
@@ -0,0 +1,275 @@
+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// A crazy linker test to:
+// - Load a library (libfoo.so) with the linker.
+// - Find the address of the "Foo" function in it.
+// - Call the function.
+// - Close the library.
+
+#include <errno.h>
+#include <pthread.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/uio.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include <crazy_linker.h>
+
+typedef void (*FunctionPtr)();
+
+static void Panic(const char* fmt, ...) {
+  va_list args;
+  fprintf(stderr, "PANIC: ");
+  va_start(args, fmt);
+  vfprintf(stderr, fmt, args);
+  va_end(args);
+  exit(1);
+}
+
+static pthread_mutex_t s_lock;
+static pthread_cond_t  s_cond;
+
+static void CheckMaps(int expected_count) {
+  printf("Checking for %d RELROs in /proc/self/maps\n", expected_count);
+
+  FILE* file = fopen("/proc/self/maps", "rb");
+  if (!file)
+    Panic("Could not open /proc/self/maps (pid %d): %s\n",
+          getpid(), strerror(errno));
+
+  char line[512];
+  int count_relros = 0;
+  printf("proc/%d/maps:\n", getpid());
+  while (fgets(line, sizeof line, file)) {
+    if (strstr(line, "with_relro")) {
+      printf("%s", line);
+      if (strstr(line, "/dev/ashmem/RELRO:"))
+        count_relros++;
+    }
+  }
+  fclose(file);
+
+  if (count_relros != expected_count)
+    Panic("Invalid shared RELRO sections in /proc/self/maps: %d"
+          " (expected %d)\n", count_relros, expected_count);
+
+  printf("RELRO count check ok!\n");
+}
+
+// Send a file descriptor |fd| through |socket|.
+// Return 0 on success, -1/errno on failure.
+static int SendFd(int socket, int fd) {
+  struct iovec iov;
+
+  char buffer[1];
+  buffer[0] = 0;
+
+  iov.iov_base = buffer;
+  iov.iov_len  = 1;
+
+  struct msghdr msg;
+  struct cmsghdr *cmsg;
+  char cms[CMSG_SPACE(sizeof(int))];
+
+  ::memset(&msg, 0, sizeof(msg));
+  msg.msg_iov        = &iov;
+  msg.msg_iovlen     = 1;
+  msg.msg_control    = reinterpret_cast<caddr_t>(cms);
+  msg.msg_controllen = CMSG_LEN(sizeof(int));
+
+  cmsg = CMSG_FIRSTHDR(&msg);
+  cmsg->cmsg_len   = CMSG_LEN(sizeof(int));
+  cmsg->cmsg_level = SOL_SOCKET;
+  cmsg->cmsg_type  = SCM_RIGHTS;
+  ::memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));
+
+  int ret = sendmsg(socket, &msg, 0);
+  if (ret < 0)
+    return -1;
+
+  if (ret != iov.iov_len) {
+    errno = EIO;
+    return -1;
+  }
+
+  return 0;
+}
+
+static int ReceiveFd(int socket, int* fd) {
+  char buffer[1];
+  struct iovec iov;
+
+  iov.iov_base = buffer;
+  iov.iov_len = 1;
+
+  struct msghdr msg;
+  struct cmsghdr *cmsg;
+  char cms[CMSG_SPACE(sizeof(int))];
+
+  ::memset(&msg, 0, sizeof msg);
+  msg.msg_name    = 0;
+  msg.msg_namelen = 0;
+  msg.msg_iov     = &iov;
+  msg.msg_iovlen  = 1;
+
+  msg.msg_control    = reinterpret_cast<caddr_t>(cms);
+  msg.msg_controllen = sizeof(cms);
+
+  int ret = recvmsg(socket, &msg, 0);
+  if (ret < 0)
+    return -1;
+  if (ret == 0) {
+    errno = EIO;
+    return -1;
+  }
+
+  cmsg = CMSG_FIRSTHDR(&msg);
+  ::memcpy(fd, CMSG_DATA(cmsg), sizeof(int));
+  return 0;
+}
+
+
+int main() {
+
+  // Initialize process-shared mutex.
+  {
+    pthread_mutexattr_t attr;
+    pthread_mutexattr_init(&attr);
+    pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED);
+    pthread_mutex_init(&s_lock, &attr);
+    pthread_mutexattr_destroy(&attr);
+  }
+  // Initialize process-shared condition variable.
+  {
+    pthread_condattr_t attr;
+    pthread_condattr_init(&attr);
+    pthread_condattr_setpshared(&attr, PTHREAD_PROCESS_SHARED);
+    pthread_cond_init(&s_cond, &attr);
+    pthread_condattr_destroy(&attr);
+  }
+
+  crazy_context_t* context = crazy_context_create();
+  crazy_library_t* library;
+
+  // Load at fixed address to simplify testing.
+  crazy_context_set_load_address(context, 0x20000000);
+
+  // Load libfoo_with_relro.so
+  if (!crazy_library_open(&library,
+                          "libfoo_with_relro.so",
+                          context)) {
+    Panic("Could not open library: %s\n", crazy_context_get_error(context));
+  }
+
+  printf("Library loaded\n");
+
+  int pipes[2];
+  if (socketpair(AF_UNIX, SOCK_STREAM, 0, pipes) < 0)
+    Panic("Could not create socket pair: %s", strerror(errno));
+
+  pid_t child = fork();
+  if (child < 0)
+    Panic("Could not fork test program!");
+
+  if (child == 0) {
+    // In the child.
+    crazy_library_info_t info;
+
+    printf("Child waiting for relro fd\n");
+    // Receive relro information from parent.
+    int relro_fd = -1;
+    if (ReceiveFd(pipes[0], &relro_fd) < 0)
+      Panic("Could not receive relro descriptor from parent");
+
+    printf("Child received relro fd %d\n", relro_fd);
+
+    int ret = TEMP_FAILURE_RETRY(::read(pipes[0], &info, sizeof(info)));
+    if (ret != static_cast<int>(sizeof(info)))
+      Panic("Could not receive relro information from parent");
+
+    info.relro_fd = relro_fd;
+    printf("Child received relro load=%p start=%p size=%p\n",
+           (void*)info.load_address, (void*)info.relro_start, (void*)info.relro_size);
+
+    if (!crazy_library_use_relro_sharing(library,
+                                         info.relro_start,
+                                         info.relro_size,
+                                         info.relro_fd,
+                                         context)) {
+      pthread_cond_signal(&s_cond);
+      Panic("Could not use RELRO sharing: %s",
+            crazy_context_get_error(context));
+    }
+
+    printf("RELRO used in child process\n");
+
+    CheckMaps(1);
+
+    FunctionPtr foo_func;
+    if (!crazy_library_find_symbol(
+            library, "Foo", reinterpret_cast<void**>(&foo_func)))
+      Panic("Could not find 'Foo' in library");
+
+    printf("Calling Foo()\n");
+    (*foo_func)();
+
+    printf("Foo called, exiting\n");
+
+    exit(0);
+
+  } else {
+    // In the parent.
+    crazy_library_info_t info;
+
+
+    printf("Parent enabling RELRO sharing\n");
+
+    // Enable RELRO sharing.
+    if (!crazy_library_enable_relro_sharing(library, context))
+      Panic("Could not enable RELRO sharing: %s",
+            crazy_context_get_error(context));
+
+    if (!crazy_library_get_info(library, context, &info))
+      Panic("Could not get library info: %s", crazy_context_get_error(context));
+
+    printf("Parent relro info load_addr=%p load_size=%p relro_start=%p relro_size=%p relro_fd=%d\n",
+           (void*)info.load_address, (void*)info.load_size,
+           (void*)info.relro_start, (void*)info.relro_size,
+           info.relro_fd);
+
+    CheckMaps(1);
+
+    if (SendFd(pipes[1], info.relro_fd) < 0)
+      Panic("Parent could not send RELRO fd: %s", strerror(errno));
+
+    int ret = TEMP_FAILURE_RETRY(::write(pipes[1], &info, sizeof(info)));
+    if (ret != static_cast<int>(sizeof(info)))
+      Panic("Parent could not send RELRO info: %s", strerror(errno));
+
+    printf("Parent waiting for child\n");
+
+    // Wait for child to complete.
+    int status;
+    waitpid(child, &status, 0);
+
+    if (WIFSIGNALED(status))
+      Panic("Child terminated by signal!!\n");
+    else if (WIFEXITED(status)) {
+      int child_status = WEXITSTATUS(status);
+      if (child_status != 0)
+        Panic("Child terminated with status=%d\n", child_status);
+    } else
+      Panic("Child exited for unknown reason!!\n");
+  }
+
+  printf("Closing library\n");
+  crazy_library_close(library);
+
+  crazy_context_destroy(context);
+  return 0;
+}