Re: Stop mesa W^X violations

[Jeremie Courreges-Anglas]

Mark Kettenis  writes:

>> From: j...@wxcvbn.org (Jeremie Courreges-Anglas)
>> Date: Mon, 27 Jun 2016 23:40:35 +0200
>> 
>> Mark Kettenis  writes:
>> 
>> > As reported by several people, mesa contains code that violates W^X.
>> > As a result glxgears aborts when using the swrast driver.  The diff
>> > below disables the offending code.  The code seems to deal the absence
>> > of W|X memory just fine.  There is a fallback path that is also used
>> > on SELinux systems.
>> >
>> > Note that the existing code would have worked just fine if mmap
>> > returned MAP_FAILED for W^X violations instead of terminating the
>> > program.  Not entirely sure what the long-term plans are.
>> 
>> [...]
>> 
>> 
>> The #ifdef excludes the definition of _mesa_exec_malloc and
>> _mesa_exec_free.
>> 
>>  xlock:/usr/X11R6/lib/modules/dri/i915_dri.so: undefined symbol 
>> '_mesa_exec_malloc'
>>  xlock:/usr/X11R6/lib/modules/dri/i915_dri.so: undefined symbol 
>> '_mesa_exec_free'
>>  libGL error: unable to load driver: i915_dri.so
>>  libGL error: driver pointer missing
>>  libGL error: failed to load driver: i915
>
> New diff that should fix this.

ok jca@

-- 
jca | PGP: 0x1524E7EE / 5135 92C1 AD36 5293 2BDF  DDCC 0DFA 74AE 1524 E7EE

Re: Stop mesa W^X violations

[Mark Kettenis]

> From: j...@wxcvbn.org (Jeremie Courreges-Anglas)
> Date: Mon, 27 Jun 2016 23:40:35 +0200
> 
> Mark Kettenis  writes:
> 
> > As reported by several people, mesa contains code that violates W^X.
> > As a result glxgears aborts when using the swrast driver.  The diff
> > below disables the offending code.  The code seems to deal the absence
> > of W|X memory just fine.  There is a fallback path that is also used
> > on SELinux systems.
> >
> > Note that the existing code would have worked just fine if mmap
> > returned MAP_FAILED for W^X violations instead of terminating the
> > program.  Not entirely sure what the long-term plans are.
> 
> [...]
> 
> 
> The #ifdef excludes the definition of _mesa_exec_malloc and
> _mesa_exec_free.
> 
>  xlock:/usr/X11R6/lib/modules/dri/i915_dri.so: undefined symbol 
> '_mesa_exec_malloc'
>  xlock:/usr/X11R6/lib/modules/dri/i915_dri.so: undefined symbol 
> '_mesa_exec_free'
>  libGL error: unable to load driver: i915_dri.so
>  libGL error: driver pointer missing
>  libGL error: failed to load driver: i915

New diff that should fix this.


Index: src/gallium/auxiliary/rtasm/rtasm_execmem.c
===
RCS file: /cvs/xenocara/lib/mesa/src/gallium/auxiliary/rtasm/rtasm_execmem.c,v
retrieving revision 1.1.1.1
diff -u -p -r1.1.1.1 rtasm_execmem.c
--- src/gallium/auxiliary/rtasm/rtasm_execmem.c 22 Nov 2015 02:43:24 -  
1.1.1.1
+++ src/gallium/auxiliary/rtasm/rtasm_execmem.c 4 Jul 2016 21:38:46 -
@@ -69,6 +69,16 @@ static struct mem_block *exec_heap = NUL
 static unsigned char *exec_mem = NULL;
 
 
+#ifdef __OpenBSD__
+
+static int
+init_heap(void)
+{
+   return 0;
+}
+
+#else
+
 static int
 init_heap(void)
 {
@@ -82,6 +92,8 @@ init_heap(void)
 
return (exec_mem != MAP_FAILED);
 }
+
+#endif
 
 
 void *
Index: src/mapi/u_execmem.c
===
RCS file: /cvs/xenocara/lib/mesa/src/mapi/u_execmem.c,v
retrieving revision 1.1.1.1
diff -u -p -r1.1.1.1 u_execmem.c
--- src/mapi/u_execmem.c22 Nov 2015 02:45:44 -  1.1.1.1
+++ src/mapi/u_execmem.c4 Jul 2016 21:38:48 -
@@ -45,8 +45,15 @@ static unsigned int head = 0;
 
 static unsigned char *exec_mem = (unsigned char *)0;
 
+#if defined(__OpenBSD__)
 
-#if defined(__linux__) || defined(__OpenBSD__) || defined(_NetBSD__) || 
defined(__sun) || defined(__HAIKU__)
+static int
+init_map(void)
+{
+  return 0;
+}
+
+#elif defined(__linux__) || defined(_NetBSD__) || defined(__sun) || 
defined(__HAIKU__)
 
 #include 
 #include 
Index: src/mesa/main/execmem.c
===
RCS file: /cvs/xenocara/lib/mesa/src/mesa/main/execmem.c,v
retrieving revision 1.1.1.1
diff -u -p -r1.1.1.1 execmem.c
--- src/mesa/main/execmem.c 22 Nov 2015 02:39:37 -  1.1.1.1
+++ src/mesa/main/execmem.c 4 Jul 2016 21:38:48 -
@@ -36,7 +36,20 @@
 
 
 
-#if defined(__linux__) || defined(__OpenBSD__) || defined(_NetBSD__) || 
defined(__sun) || defined(__HAIKU__)
+#if defined(__OpenBSD__)
+
+void *
+_mesa_exec_malloc(GLuint size)
+{
+   return NULL;
+}
+
+void
+_mesa_exec_free(void *addr)
+{
+}
+
+#elif defined(__linux__) || defined(_NetBSD__) || defined(__sun) || 
defined(__HAIKU__)
 
 /*
  * Allocate a large block of memory which can hold code then dole it out

Re: Stop mesa W^X violations

[Jeremie Courreges-Anglas]

Mark Kettenis  writes:

> As reported by several people, mesa contains code that violates W^X.
> As a result glxgears aborts when using the swrast driver.  The diff
> below disables the offending code.  The code seems to deal the absence
> of W|X memory just fine.  There is a fallback path that is also used
> on SELinux systems.
>
> Note that the existing code would have worked just fine if mmap
> returned MAP_FAILED for W^X violations instead of terminating the
> program.  Not entirely sure what the long-term plans are.

[...]

> Index: src/mesa/main/execmem.c
> ===
> RCS file: /cvs/xenocara/lib/mesa/src/mesa/main/execmem.c,v
> retrieving revision 1.1.1.1
> diff -u -p -r1.1.1.1 execmem.c
> --- src/mesa/main/execmem.c   22 Nov 2015 02:39:37 -  1.1.1.1
> +++ src/mesa/main/execmem.c   20 Jun 2016 20:08:40 -
> @@ -36,7 +36,15 @@
>  
>  
>  
> -#if defined(__linux__) || defined(__OpenBSD__) || defined(_NetBSD__) || 
> defined(__sun) || defined(__HAIKU__)
> +#if defined(__OpenBSD__)
> +
> +static int
> +init_heap(void)
> +{
> +  return 0;
> +}

The #ifdef excludes the definition of _mesa_exec_malloc and
_mesa_exec_free.

 xlock:/usr/X11R6/lib/modules/dri/i915_dri.so: undefined symbol 
'_mesa_exec_malloc'
 xlock:/usr/X11R6/lib/modules/dri/i915_dri.so: undefined symbol 
'_mesa_exec_free'
 libGL error: unable to load driver: i915_dri.so
 libGL error: driver pointer missing
 libGL error: failed to load driver: i915

> +
> +#elif defined(__linux__) || defined(_NetBSD__) || defined(__sun) || 
> defined(__HAIKU__)
>  
>  /*
>   * Allocate a large block of memory which can hold code then dole it out
>

-- 
jca | PGP: 0x1524E7EE / 5135 92C1 AD36 5293 2BDF  DDCC 0DFA 74AE 1524 E7EE

Re: Stop mesa W^X violations

[Matthieu Herrb]

On Mon, Jun 20, 2016 at 10:22:58PM +0200, Mark Kettenis wrote:
> As reported by several people, mesa contains code that violates W^X.
> As a result glxgears aborts when using the swrast driver.  The diff
> below disables the offending code.  The code seems to deal the absence
> of W|X memory just fine.  There is a fallback path that is also used
> on SELinux systems.
> 
> Note that the existing code would have worked just fine if mmap
> returned MAP_FAILED for W^X violations instead of terminating the
> program.  Not entirely sure what the long-term plans are.
>

Ok matthieu@

> 
> Index: src/gallium/auxiliary/rtasm/rtasm_execmem.c
> ===
> RCS file: /cvs/xenocara/lib/mesa/src/gallium/auxiliary/rtasm/rtasm_execmem.c,v
> retrieving revision 1.1.1.1
> diff -u -p -r1.1.1.1 rtasm_execmem.c
> --- src/gallium/auxiliary/rtasm/rtasm_execmem.c   22 Nov 2015 02:43:24 
> -  1.1.1.1
> +++ src/gallium/auxiliary/rtasm/rtasm_execmem.c   20 Jun 2016 20:08:37 
> -
> @@ -69,6 +69,16 @@ static struct mem_block *exec_heap = NUL
>  static unsigned char *exec_mem = NULL;
>  
>  
> +#ifdef __OpenBSD__
> +
> +static int
> +init_heap(void)
> +{
> +   return 0;
> +}
> +
> +#else
> +
>  static int
>  init_heap(void)
>  {
> @@ -82,6 +92,8 @@ init_heap(void)
>  
> return (exec_mem != MAP_FAILED);
>  }
> +
> +#endif
>  
>  
>  void *
> Index: src/mapi/u_execmem.c
> ===
> RCS file: /cvs/xenocara/lib/mesa/src/mapi/u_execmem.c,v
> retrieving revision 1.1.1.1
> diff -u -p -r1.1.1.1 u_execmem.c
> --- src/mapi/u_execmem.c  22 Nov 2015 02:45:44 -  1.1.1.1
> +++ src/mapi/u_execmem.c  20 Jun 2016 20:08:39 -
> @@ -45,8 +45,15 @@ static unsigned int head = 0;
>  
>  static unsigned char *exec_mem = (unsigned char *)0;
>  
> +#if defined(__OpenBSD__)
>  
> -#if defined(__linux__) || defined(__OpenBSD__) || defined(_NetBSD__) || 
> defined(__sun) || defined(__HAIKU__)
> +static int
> +init_map(void)
> +{
> +  return 0;
> +}
> +
> +#elif defined(__linux__) || defined(_NetBSD__) || defined(__sun) || 
> defined(__HAIKU__)
>  
>  #include 
>  #include 
> Index: src/mesa/main/execmem.c
> ===
> RCS file: /cvs/xenocara/lib/mesa/src/mesa/main/execmem.c,v
> retrieving revision 1.1.1.1
> diff -u -p -r1.1.1.1 execmem.c
> --- src/mesa/main/execmem.c   22 Nov 2015 02:39:37 -  1.1.1.1
> +++ src/mesa/main/execmem.c   20 Jun 2016 20:08:40 -
> @@ -36,7 +36,15 @@
>  
>  
>  
> -#if defined(__linux__) || defined(__OpenBSD__) || defined(_NetBSD__) || 
> defined(__sun) || defined(__HAIKU__)
> +#if defined(__OpenBSD__)
> +
> +static int
> +init_heap(void)
> +{
> +  return 0;
> +}
> +
> +#elif defined(__linux__) || defined(_NetBSD__) || defined(__sun) || 
> defined(__HAIKU__)
>  
>  /*
>   * Allocate a large block of memory which can hold code then dole it out

-- 
Matthieu Herrb


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Re: Stop mesa W^X violations

[Theo de Raadt]

>Note that the existing code would have worked just fine if mmap
>returned MAP_FAILED for W^X violations instead of terminating the
>program.  Not entirely sure what the long-term plans are.

Yeah, I am not sure of the long-term plans yet either.  In discussions
with the ports people the idea was fail-hard behaviour for a while,
then we'll try error returns for a while, and maybe we need to see-saw
a few times.  The approach is still very focused on creating awareness
amongst the "right people" who can fix things.

Stop mesa W^X violations

[Mark Kettenis]

As reported by several people, mesa contains code that violates W^X.
As a result glxgears aborts when using the swrast driver.  The diff
below disables the offending code.  The code seems to deal the absence
of W|X memory just fine.  There is a fallback path that is also used
on SELinux systems.

Note that the existing code would have worked just fine if mmap
returned MAP_FAILED for W^X violations instead of terminating the
program.  Not entirely sure what the long-term plans are.


Index: src/gallium/auxiliary/rtasm/rtasm_execmem.c
===
RCS file: /cvs/xenocara/lib/mesa/src/gallium/auxiliary/rtasm/rtasm_execmem.c,v
retrieving revision 1.1.1.1
diff -u -p -r1.1.1.1 rtasm_execmem.c
--- src/gallium/auxiliary/rtasm/rtasm_execmem.c 22 Nov 2015 02:43:24 -  
1.1.1.1
+++ src/gallium/auxiliary/rtasm/rtasm_execmem.c 20 Jun 2016 20:08:37 -
@@ -69,6 +69,16 @@ static struct mem_block *exec_heap = NUL
 static unsigned char *exec_mem = NULL;
 
 
+#ifdef __OpenBSD__
+
+static int
+init_heap(void)
+{
+   return 0;
+}
+
+#else
+
 static int
 init_heap(void)
 {
@@ -82,6 +92,8 @@ init_heap(void)
 
return (exec_mem != MAP_FAILED);
 }
+
+#endif
 
 
 void *
Index: src/mapi/u_execmem.c
===
RCS file: /cvs/xenocara/lib/mesa/src/mapi/u_execmem.c,v
retrieving revision 1.1.1.1
diff -u -p -r1.1.1.1 u_execmem.c
--- src/mapi/u_execmem.c22 Nov 2015 02:45:44 -  1.1.1.1
+++ src/mapi/u_execmem.c20 Jun 2016 20:08:39 -
@@ -45,8 +45,15 @@ static unsigned int head = 0;
 
 static unsigned char *exec_mem = (unsigned char *)0;
 
+#if defined(__OpenBSD__)
 
-#if defined(__linux__) || defined(__OpenBSD__) || defined(_NetBSD__) || 
defined(__sun) || defined(__HAIKU__)
+static int
+init_map(void)
+{
+  return 0;
+}
+
+#elif defined(__linux__) || defined(_NetBSD__) || defined(__sun) || 
defined(__HAIKU__)
 
 #include 
 #include 
Index: src/mesa/main/execmem.c
===
RCS file: /cvs/xenocara/lib/mesa/src/mesa/main/execmem.c,v
retrieving revision 1.1.1.1
diff -u -p -r1.1.1.1 execmem.c
--- src/mesa/main/execmem.c 22 Nov 2015 02:39:37 -  1.1.1.1
+++ src/mesa/main/execmem.c 20 Jun 2016 20:08:40 -
@@ -36,7 +36,15 @@
 
 
 
-#if defined(__linux__) || defined(__OpenBSD__) || defined(_NetBSD__) || 
defined(__sun) || defined(__HAIKU__)
+#if defined(__OpenBSD__)
+
+static int
+init_heap(void)
+{
+  return 0;
+}
+
+#elif defined(__linux__) || defined(_NetBSD__) || defined(__sun) || 
defined(__HAIKU__)
 
 /*
  * Allocate a large block of memory which can hold code then dole it out