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Remove exploitable LD_BIND_NOW hack (CVE-2009-1894).

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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.
This commit is contained in:
Diego Elio 'Flameeyes' Pettenò 2009-07-07 20:51:53 +02:00
parent ff252cb48d
commit 84200b423e
3 changed files with 8 additions and 24 deletions
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6
configure.ac
View file

@ -113,6 +113,12 @@ 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 for the proper way to build libraries that have no undefined
dnl symbols; on some hosts this needs to be avoided but the macro
dnl takes care of it.

4
src/Makefile.am
View file

@ -183,9 +183,9 @@ 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
###################################

22
src/daemon/main.c
View file

@ -401,28 +401,6 @@ 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
if ((e = getenv("PULSE_PASSED_FD"))) {
passed_fd = atoi(e);