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authorAndrew Tridgell <tridge@samba.org>2008-08-24 13:56:59 +1000
committerMichael Adam <obnox@samba.org>2008-08-26 14:39:42 +0200
commitd9f61dbdc91fae6560361f98d981b1f7bea80422 (patch)
tree6be75509fe252fdf14a309dfe311947a0bb9ed50
parent52c39dd55d0a3eda3e9ed9a0981f546ca7b88cff (diff)
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Avoid a race condition in glibc between AIO and setresuid().
See this test: http://samba.org/~tridge/junkcode/aio_uid.c The problem is that setresuid() tries to be clever about threads, and tries to change the euid of any threads that are running. If a AIO read or write completes while this is going on then the signal from the thread where the IO completed is lost, as it gets -1/EPERM from rt_sigqueueinfo() The simplest fix is to try to use setreuid() instead of setresuid(), as setreuid() doesn't try to be clever. Unfortunately this also means we must use become_root()/unbecome_root() in the aio code. (This used to be commit 56c5a6f024875bb79b0104beb36f6b0ec1e1e9f9)
-rw-r--r--source3/configure.in24
1 files changed, 13 insertions, 11 deletions
diff --git a/source3/configure.in b/source3/configure.in
index 5508d9b01d..9436fed1ff 100644
--- a/source3/configure.in
+++ b/source3/configure.in
@@ -2627,30 +2627,32 @@ AC_CHECK_FUNCS(getpagesize)
################################################
# look for a method of setting the effective uid
seteuid=no;
+
if test $seteuid = no; then
-AC_CACHE_CHECK([for setresuid],samba_cv_USE_SETRESUID,[
+AC_CACHE_CHECK([for setreuid],samba_cv_USE_SETREUID,[
AC_TRY_RUN([
#define AUTOCONF_TEST 1
-#define USE_SETRESUID 1
+#define USE_SETREUID 1
#include "confdefs.h"
#include "${srcdir-.}/lib/util_sec.c"],
- samba_cv_USE_SETRESUID=yes,samba_cv_USE_SETRESUID=no,samba_cv_USE_SETRESUID=cross)])
-if test x"$samba_cv_USE_SETRESUID" = x"yes"; then
- seteuid=yes;AC_DEFINE(USE_SETRESUID,1,[Whether setresuid() is available])
+ samba_cv_USE_SETREUID=yes,samba_cv_USE_SETREUID=no,samba_cv_USE_SETREUID=cross)])
+if test x"$samba_cv_USE_SETREUID" = x"yes"; then
+ seteuid=yes;AC_DEFINE(USE_SETREUID,1,[Whether setreuid() is available])
fi
fi
-
+# we check for setresuid second as it conflicts with AIO on Linux.
+# see http://samba.org/~tridge/junkcode/aio_uid.c
if test $seteuid = no; then
-AC_CACHE_CHECK([for setreuid],samba_cv_USE_SETREUID,[
+AC_CACHE_CHECK([for setresuid],samba_cv_USE_SETRESUID,[
AC_TRY_RUN([
#define AUTOCONF_TEST 1
-#define USE_SETREUID 1
+#define USE_SETRESUID 1
#include "confdefs.h"
#include "${srcdir-.}/lib/util_sec.c"],
- samba_cv_USE_SETREUID=yes,samba_cv_USE_SETREUID=no,samba_cv_USE_SETREUID=cross)])
-if test x"$samba_cv_USE_SETREUID" = x"yes"; then
- seteuid=yes;AC_DEFINE(USE_SETREUID,1,[Whether setreuid() is available])
+ samba_cv_USE_SETRESUID=yes,samba_cv_USE_SETRESUID=no,samba_cv_USE_SETRESUID=cross)])
+if test x"$samba_cv_USE_SETRESUID" = x"yes"; then
+ seteuid=yes;AC_DEFINE(USE_SETRESUID,1,[Whether setresuid() is available])
fi
fi