diff mbox series

[v8,2/4] elf: Fix initial-exec TLS access on audit modules (BZ #28096)

Message ID 20211228115056.3613468-3-adhemerval.zanella@linaro.org
State Superseded
Headers show
Series Multiple rtld-audit fixes | expand

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent

Commit Message

Adhemerval Zanella Dec. 28, 2021, 11:50 a.m. UTC
For audit modules or dependencies with initial-exec TLS, we can not
set the initial TLS image on default loader initialization because it
would already be set by the audit setup.  However, subsequent thread
creation would need to follow the default behaviour.

This patch fixes by initializing the TLS arena only for base
namespace (LM_ID_BASE).

Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
---
 elf/Makefile          |  8 +++++
 elf/dl-tls.c          | 16 ++++++---
 elf/tst-audit21.c     | 42 +++++++++++++++++++++++
 elf/tst-auditmod21a.c | 80 +++++++++++++++++++++++++++++++++++++++++++
 elf/tst-auditmod21b.c | 22 ++++++++++++
 5 files changed, 164 insertions(+), 4 deletions(-)
 create mode 100644 elf/tst-audit21.c
 create mode 100644 elf/tst-auditmod21a.c
 create mode 100644 elf/tst-auditmod21b.c

Comments

Adhemerval Zanella Dec. 31, 2021, 12:25 p.m. UTC | #1
On 28/12/2021 08:50, Adhemerval Zanella wrote:
> diff --git a/elf/dl-tls.c b/elf/dl-tls.c
> index 273f60f233..c57fc13be6 100644
> --- a/elf/dl-tls.c
> +++ b/elf/dl-tls.c
> @@ -593,10 +593,18 @@ _dl_allocate_tls_init (void *result)
>  	     some platforms use in static programs requires it.  */
>  	  dtv[map->l_tls_modid].pointer.val = dest;
>  
> -	  /* Copy the initialization image and clear the BSS part.  */
> -	  memset (__mempcpy (dest, map->l_tls_initimage,
> -			     map->l_tls_initimage_size), '\0',
> -		  map->l_tls_blocksize - map->l_tls_initimage_size);
> +	  /* Copy the initialization image and clear the BSS part.  For
> +	     audit modules or depedencies with initial-exec TLS, we can not
> +	     set the initial TLS image on default loader initialization
> +	     because it would already be set by the audit setup.  However,
> +	     subsequent thread creation would need to follow the default
> +	     behaviour.   */
> +	  if (__glibc_likely (map->l_ns == LM_ID_BASE))
> +	    memset (__mempcpy (dest, map->l_tls_initimage,
> +			       map->l_tls_initimage_size), '\0',
> +		    map->l_tls_blocksize - map->l_tls_initimage_size);
> +	  //else
> +	  //  map->l_dont_set_tls_static = 0;
>  	}
>  
>        total += cnt;

This is wrong is triggers a regression (nptl/tst-audit-threads).  I will
send an updated version.
diff mbox series

Patch

diff --git a/elf/Makefile b/elf/Makefile
index 861c351510..3a521ae89e 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -233,6 +233,7 @@  tests += restest1 preloadtest loadfail multiload origtest resolvfail \
 	 tst-audit18 \
 	 tst-audit19b \
 	 tst-audit20 \
+	 tst-audit21 \
 	 tst-audit22 \
 	 tst-audit23 \
 #	 reldep9
@@ -385,6 +386,8 @@  modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
 		tst-auditmod19b \
 		tst-audit19bmod \
 		tst-auditmod20 \
+		tst-auditmod21a \
+		tst-auditmod21b \
 		tst-auditmod22 \
 		tst-auditmod23 \
 		tst-audit23mod \
@@ -1603,6 +1606,11 @@  tst-audit19b-ARGS = -- $(host-test-program-cmd)
 $(objpfx)tst-audit20.out: $(objpfx)tst-auditmod20.so
 tst-audit20-ENV = LD_AUDIT=$(objpfx)tst-auditmod20.so
 
+$(objpfx)tst-audit21: $(shared-thread-library)
+$(objpfx)tst-audit21.out: $(objpfx)tst-auditmod21a.so
+$(objpfx)tst-auditmod21a.so: $(objpfx)tst-auditmod21b.so
+tst-audit21-ENV = LD_AUDIT=$(objpfx)tst-auditmod21a.so
+
 $(objpfx)tst-audit22.out: $(objpfx)tst-auditmod22.so
 tst-audit22-ARGS = -- $(host-test-program-cmd)
 
diff --git a/elf/dl-tls.c b/elf/dl-tls.c
index 273f60f233..c57fc13be6 100644
--- a/elf/dl-tls.c
+++ b/elf/dl-tls.c
@@ -593,10 +593,18 @@  _dl_allocate_tls_init (void *result)
 	     some platforms use in static programs requires it.  */
 	  dtv[map->l_tls_modid].pointer.val = dest;
 
-	  /* Copy the initialization image and clear the BSS part.  */
-	  memset (__mempcpy (dest, map->l_tls_initimage,
-			     map->l_tls_initimage_size), '\0',
-		  map->l_tls_blocksize - map->l_tls_initimage_size);
+	  /* Copy the initialization image and clear the BSS part.  For
+	     audit modules or depedencies with initial-exec TLS, we can not
+	     set the initial TLS image on default loader initialization
+	     because it would already be set by the audit setup.  However,
+	     subsequent thread creation would need to follow the default
+	     behaviour.   */
+	  if (__glibc_likely (map->l_ns == LM_ID_BASE))
+	    memset (__mempcpy (dest, map->l_tls_initimage,
+			       map->l_tls_initimage_size), '\0',
+		    map->l_tls_blocksize - map->l_tls_initimage_size);
+	  //else
+	  //  map->l_dont_set_tls_static = 0;
 	}
 
       total += cnt;
diff --git a/elf/tst-audit21.c b/elf/tst-audit21.c
new file mode 100644
index 0000000000..307cb6fc3b
--- /dev/null
+++ b/elf/tst-audit21.c
@@ -0,0 +1,42 @@ 
+/* Check DT_AUDIT with static TLS.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <ctype.h>
+#include <support/xthread.h>
+#include <support/check.h>
+
+static volatile __thread int out __attribute__ ((tls_model ("initial-exec")));
+
+static void *
+tf (void *arg)
+{
+  TEST_COMPARE (out, 0);
+  out = isspace (' ');
+  return NULL;
+}
+
+int main (int argc, char *argv[])
+{
+  TEST_COMPARE (out, 0);
+  out = isspace (' ');
+
+  pthread_t t = xpthread_create (NULL, tf, NULL);
+  xpthread_join (t);
+
+  return 0;
+}
diff --git a/elf/tst-auditmod21a.c b/elf/tst-auditmod21a.c
new file mode 100644
index 0000000000..f00470e105
--- /dev/null
+++ b/elf/tst-auditmod21a.c
@@ -0,0 +1,80 @@ 
+/* Check DT_AUDIT with static TLS.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <ctype.h>
+#include <stdlib.h>
+#include <link.h>
+
+#define tls_ie __attribute__ ((tls_model ("initial-exec")))
+
+__thread int tls_var0 tls_ie;
+__thread int tls_var1 tls_ie = 0x10;
+
+/* Defined at tst-auditmod21b.so  */
+extern __thread int tls_var2;
+extern __thread int tls_var3;
+
+static volatile int out;
+
+static void
+call_libc (void)
+{
+  /* isspace access the initial-exec glibc TLS variables, which are
+     setup in glibc initialization.  */
+  out = isspace (' ');
+}
+
+unsigned int
+la_version (unsigned int v)
+{
+  tls_var0 = 0x1;
+  if (tls_var1 != 0x10)
+    abort ();
+  tls_var1 = 0x20;
+
+  tls_var2 = 0x2;
+  if (tls_var3 != 0x20)
+    abort ();
+  tls_var3 = 0x40;
+
+  call_libc ();
+
+  return LAV_CURRENT;
+}
+
+unsigned int
+la_objopen (struct link_map* map, Lmid_t lmid, uintptr_t* cookie)
+{
+  call_libc ();
+  *cookie = (uintptr_t) map;
+  return 0;
+}
+
+void
+la_activity (uintptr_t* cookie, unsigned int flag)
+{
+  if (tls_var0 != 0x1 || tls_var1 != 0x20)
+    abort ();
+  call_libc ();
+}
+
+void
+la_preinit (uintptr_t* cookie)
+{
+  call_libc ();
+}
diff --git a/elf/tst-auditmod21b.c b/elf/tst-auditmod21b.c
new file mode 100644
index 0000000000..550f858b1d
--- /dev/null
+++ b/elf/tst-auditmod21b.c
@@ -0,0 +1,22 @@ 
+/* Check DT_AUDIT with static TLS.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#define tls_ie __attribute__ ((tls_model ("initial-exec")))
+
+__thread int tls_var2 tls_ie;
+__thread int tls_var3 tls_ie = 0x20;