Redirect fopen("/dev/urandom") so that NSS can properly seed its RNG.
BUG=122169
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=131808
Review URL: https://chromiumcodereview.appspot.com/10031027
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@132106 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/content/browser/zygote_main_linux.cc b/content/browser/zygote_main_linux.cc
index 944163c63..671c7ce99 100644
--- a/content/browser/zygote_main_linux.cc
+++ b/content/browser/zygote_main_linux.cc
@@ -7,6 +7,7 @@
#include <dlfcn.h>
#include <fcntl.h>
#include <pthread.h>
+#include <stdio.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
@@ -25,6 +26,7 @@
#include "base/pickle.h"
#include "base/process_util.h"
#include "base/rand_util.h"
+#include "base/rand_util_c.h"
#include "base/sys_info.h"
#include "build/build_config.h"
#include "crypto/nss_util.h"
@@ -64,6 +66,8 @@
static const int kZygoteIdDescriptor = 7;
static bool g_suid_sandbox_active = false;
+static const char kUrandomDevPath[] = "/dev/urandom";
+
#if defined(SECCOMP_SANDBOX)
static int g_proc_fd = -1;
#endif
@@ -632,16 +636,26 @@
typedef struct tm* (*LocaltimeFunction)(const time_t* timep);
typedef struct tm* (*LocaltimeRFunction)(const time_t* timep,
struct tm* result);
+typedef FILE* (*FopenFunction)(const char* path, const char* mode);
+typedef int (*XstatFunction)(int version, const char *path, struct stat *buf);
+typedef int (*Xstat64Function)(int version, const char *path,
+ struct stat64 *buf);
static pthread_once_t g_libc_localtime_funcs_guard = PTHREAD_ONCE_INIT;
static LocaltimeFunction g_libc_localtime;
static LocaltimeRFunction g_libc_localtime_r;
+static pthread_once_t g_libc_file_io_funcs_guard = PTHREAD_ONCE_INIT;
+static FopenFunction g_libc_fopen;
+static FopenFunction g_libc_fopen64;
+static XstatFunction g_libc_xstat;
+static Xstat64Function g_libc_xstat64;
+
static void InitLibcLocaltimeFunctions() {
g_libc_localtime = reinterpret_cast<LocaltimeFunction>(
- dlsym(RTLD_NEXT, "localtime"));
+ dlsym(RTLD_NEXT, "localtime"));
g_libc_localtime_r = reinterpret_cast<LocaltimeRFunction>(
- dlsym(RTLD_NEXT, "localtime_r"));
+ dlsym(RTLD_NEXT, "localtime_r"));
if (!g_libc_localtime || !g_libc_localtime_r) {
// http://code.google.com/p/chromium/issues/detail?id=16800
@@ -686,6 +700,125 @@
}
}
+// TODO(sergeyu): Currently this code doesn't work properly under ASAN
+// - it crashes content_unittests. Make sure it works properly and
+// enable it here. http://crbug.com/123263
+#if !defined(ADDRESS_SANITIZER)
+
+static void InitLibcFileIOFunctions() {
+ g_libc_fopen = reinterpret_cast<FopenFunction>(
+ dlsym(RTLD_NEXT, "fopen"));
+ g_libc_fopen64 = reinterpret_cast<FopenFunction>(
+ dlsym(RTLD_NEXT, "fopen64"));
+
+ if (!g_libc_fopen) {
+ LOG(FATAL) << "Failed to get fopen() from libc.";
+ } else if (!g_libc_fopen64) {
+#if !defined(OS_OPENBSD) && !defined(OS_FREEBSD)
+ LOG(WARNING) << "Failed to get fopen64() from libc. Using fopen() instead.";
+#endif // !defined(OS_OPENBSD) && !defined(OS_FREEBSD)
+ g_libc_fopen64 = g_libc_fopen;
+ }
+
+ // TODO(sergeyu): This works only on systems with glibc. Fix it to
+ // work properly on other systems if necessary.
+ g_libc_xstat = reinterpret_cast<XstatFunction>(
+ dlsym(RTLD_NEXT, "__xstat"));
+ g_libc_xstat64 = reinterpret_cast<Xstat64Function>(
+ dlsym(RTLD_NEXT, "__xstat64"));
+
+ if (!g_libc_xstat) {
+ LOG(FATAL) << "Failed to get __xstat() from libc.";
+ }
+ if (!g_libc_xstat64) {
+ LOG(WARNING) << "Failed to get __xstat64() from libc.";
+ }
+}
+
+// fopen() and fopen64() are intercepted here so that NSS can open
+// /dev/urandom to seed its random number generator. NSS is used by
+// remoting in the sendbox.
+
+// fopen() call may be redirected to fopen64() in stdio.h using
+// __REDIRECT(), which sets asm name for fopen() to "fopen64". This
+// means that we cannot override fopen() directly here. Instead the
+// the code below defines fopen_override() function with asm name
+// "fopen", so that all references to fopen() will resolve to this
+// function.
+__attribute__ ((__visibility__("default")))
+FILE* fopen_override(const char* path, const char* mode) __asm__ ("fopen");
+
+__attribute__ ((__visibility__("default")))
+FILE* fopen_override(const char* path, const char* mode) {
+ if (g_am_zygote_or_renderer && strcmp(path, kUrandomDevPath) == 0) {
+ int fd = HANDLE_EINTR(dup(GetUrandomFD()));
+ if (fd < 0) {
+ PLOG(ERROR) << "dup() failed.";
+ return NULL;
+ }
+ return fdopen(fd, mode);
+ } else {
+ CHECK_EQ(0, pthread_once(&g_libc_file_io_funcs_guard,
+ InitLibcFileIOFunctions));
+ return g_libc_fopen(path, mode);
+ }
+}
+
+__attribute__ ((__visibility__("default")))
+FILE* fopen64(const char* path, const char* mode) {
+ if (g_am_zygote_or_renderer && strcmp(path, kUrandomDevPath) == 0) {
+ int fd = HANDLE_EINTR(dup(GetUrandomFD()));
+ if (fd < 0) {
+ PLOG(ERROR) << "dup() failed.";
+ return NULL;
+ }
+ return fdopen(fd, mode);
+ } else {
+ CHECK_EQ(0, pthread_once(&g_libc_file_io_funcs_guard,
+ InitLibcFileIOFunctions));
+ return g_libc_fopen64(path, mode);
+ }
+}
+
+// stat() is subject to the same problem as fopen(), so we have to use
+// the same trick to override it.
+__attribute__ ((__visibility__("default")))
+int xstat_override(int version,
+ const char *path,
+ struct stat *buf) __asm__ ("__xstat");
+
+__attribute__ ((__visibility__("default")))
+int xstat_override(int version, const char *path, struct stat *buf) {
+ if (g_am_zygote_or_renderer && strcmp(path, kUrandomDevPath) == 0) {
+ int result = __fxstat(version, GetUrandomFD(), buf);
+ return result;
+ } else {
+ CHECK_EQ(0, pthread_once(&g_libc_file_io_funcs_guard,
+ InitLibcFileIOFunctions));
+ return g_libc_xstat(version, path, buf);
+ }
+}
+
+__attribute__ ((__visibility__("default")))
+int xstat64_override(int version,
+ const char *path,
+ struct stat64 *buf) __asm__ ("__xstat64");
+
+__attribute__ ((__visibility__("default")))
+int xstat64_override(int version, const char *path, struct stat64 *buf) {
+ if (g_am_zygote_or_renderer && strcmp(path, kUrandomDevPath) == 0) {
+ int result = __fxstat64(version, GetUrandomFD(), buf);
+ return result;
+ } else {
+ CHECK_EQ(0, pthread_once(&g_libc_file_io_funcs_guard,
+ InitLibcFileIOFunctions));
+ CHECK(g_libc_xstat64);
+ return g_libc_xstat64(version, path, buf);
+ }
+}
+
+#endif // !ADDRESS_SANITIZER
+
#endif // !CHROMIUM_SELINUX
// This function triggers the static and lazy construction of objects that need
