From abf6dfbc625006f08fb30fef5814d0c7eb57e2ee Mon Sep 17 00:00:00 2001
From: Diego Elio 'Flameeyes' Pettenò <flameeyes@gmail.com>
Date: Tue, 7 Jul 2009 20:51:53 +0200
Subject: Remove exploitable LD_BIND_NOW hack (CVE-2009-1894).

Instead of trying to re-execute pulseaudio itself with LD_BIND_NOW set,
just find the correct flag for the linker to request immediate bindings
(all ELF files support that option), and use that when linking the daemon.

Reduce the amount of compiled and executed code as well.
---
 configure.ac      |  6 ++++++
 src/Makefile.am   |  4 ++--
 src/daemon/main.c | 22 ----------------------
 3 files changed, 8 insertions(+), 24 deletions(-)

diff --git a/configure.ac b/configure.ac
index 25cee577..690c2a89 100644
--- a/configure.ac
+++ b/configure.ac
@@ -114,6 +114,12 @@ CC_CHECK_LDFLAGS([${tmp_ldflag}],
     [VERSIONING_LDFLAGS='-Wl,-version-script=$(srcdir)/map-file'])
 AC_SUBST([VERSIONING_LDFLAGS])
 
+dnl Use immediate (now) bindings; avoids the funky re-call in itself
+dnl  the -z now syntax is lifted from Sun's linker and works with GNU's too
+dnl  other linkes might be added later
+CC_CHECK_LDFLAGS([-Wl,-z,now], [IMMEDIATE_LDFLAGS="-Wl,-z,now"])
+AC_SUBST([IMMEDIATE_LDFLAGS])
+
 dnl Check whether to build tests by default (as compile-test) or not
 AC_ARG_ENABLE([default-build-tests],
     AS_HELP_STRING([--disable-default-build-tests], [Build test programs only during make check]))
diff --git a/src/Makefile.am b/src/Makefile.am
index 0d4f53af..413cae1e 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -153,9 +153,9 @@ PREOPEN_LIBS = $(modlibexec_LTLIBRARIES)
 endif
 
 if FORCE_PREOPEN
-pulseaudio_LDFLAGS = $(AM_LDFLAGS) $(BINLDFLAGS) -dlpreopen force $(foreach f,$(PREOPEN_LIBS),-dlpreopen $(f))
+pulseaudio_LDFLAGS = $(AM_LDFLAGS) $(BINLDFLAGS) $(IMMEDIATE_LDFLAGS) -dlpreopen force $(foreach f,$(PREOPEN_LIBS),-dlpreopen $(f))
 else
-pulseaudio_LDFLAGS = $(AM_LDFLAGS) $(BINLDFLAGS) -dlopen force $(foreach f,$(PREOPEN_LIBS),-dlopen $(f))
+pulseaudio_LDFLAGS = $(AM_LDFLAGS) $(BINLDFLAGS) $(IMMEDIATE_LDFLAGS) -dlopen force $(foreach f,$(PREOPEN_LIBS),-dlopen $(f))
 endif
 
 if HAVE_POLKIT
diff --git a/src/daemon/main.c b/src/daemon/main.c
index c456e6d1..4499ea34 100644
--- a/src/daemon/main.c
+++ b/src/daemon/main.c
@@ -399,28 +399,6 @@ int main(int argc, char *argv[]) {
     pa_log_set_level(PA_LOG_NOTICE);
     pa_log_set_flags(PA_LOG_COLORS|PA_LOG_PRINT_FILE|PA_LOG_PRINT_LEVEL, PA_LOG_RESET);
 
-#if defined(__linux__) && defined(__OPTIMIZE__)
-    /*
-       Disable lazy relocations to make usage of external libraries
-       more deterministic for our RT threads. We abuse __OPTIMIZE__ as
-       a check whether we are a debug build or not.
-    */
-
-    if (!getenv("LD_BIND_NOW")) {
-        char *rp;
-
-        /* We have to execute ourselves, because the libc caches the
-         * value of $LD_BIND_NOW on initialization. */
-
-        pa_set_env("LD_BIND_NOW", "1");
-
-        if ((rp = pa_readlink("/proc/self/exe")))
-            pa_assert_se(execv(rp, argv) == 0);
-        else
-            pa_log_warn("Couldn't read /proc/self/exe, cannot self execute. Running in a chroot()?");
-    }
-#endif
-
 #ifdef HAVE_GETUID
     real_root = getuid() == 0;
     suid_root = !real_root && geteuid() == 0;
-- 
cgit