The documentation for /proc/sys/kernel/* does not mention the possible
value 2 for randomize-va-space (but already mentions what it does).
Signed-off-by: Horst Schirmeier <[email protected]>
---
Documentation/sysctl/kernel.txt | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 322a00b..b2af4ef 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -310,7 +310,7 @@ that support this feature.
loaded to random addresses. Also for PIE-linked binaries, the location
of code start is randomized.
- With heap randomization, the situation is a little bit more
+2 - With heap randomization, the situation is a little bit more
complicated.
There a few legacy applications out there (such as some ancient
versions of libc.so.5 from 1996) that assume that brk area starts
--
PGP-Key 0xD40E0E7A
On Thu, 2 Jul 2009, Horst Schirmeier wrote:
> The documentation for /proc/sys/kernel/* does not mention the possible
> value 2 for randomize-va-space (but already mentions what it does).
Hmm, while you are at it ...
> Documentation/sysctl/kernel.txt | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
> index 322a00b..b2af4ef 100644
> --- a/Documentation/sysctl/kernel.txt
> +++ b/Documentation/sysctl/kernel.txt
> @@ -310,7 +310,7 @@ that support this feature.
> loaded to random addresses. Also for PIE-linked binaries, the location
> of code start is randomized.
>
> - With heap randomization, the situation is a little bit more
> +2 - With heap randomization, the situation is a little bit more
> complicated.
> There a few legacy applications out there (such as some ancient
... would you please fix this typo/grammo as well? (There a few ...)
> versions of libc.so.5 from 1996) that assume that brk area starts
Also, the text itself doesn't seem to be super-clear ... namely, it
describes what CONFIG_COMPAT_BRK is about, but doesn't really clarify how
exactly does this correlate with randomize_va_space == 2. Would you mind
also fixing this bit?
Thanks,
--
Jiri Kosina
SUSE Labs
On Fri, 03 Jul 2009, Jiri Kosina wrote:
> > There a few legacy applications out there (such as some ancient
>
> ... would you please fix this typo/grammo as well? (There a few ...)
>
> > versions of libc.so.5 from 1996) that assume that brk area starts
>
> Also, the text itself doesn't seem to be super-clear ... namely, it
> describes what CONFIG_COMPAT_BRK is about, but doesn't really clarify how
> exactly does this correlate with randomize_va_space == 2. Would you mind
> also fixing this bit?
I hope I didn't misread the sources :-) Opinions?
---
The documentation for /proc/sys/kernel/* does not mention the possible
value 2 for randomize-va-space yet. While being there, doing some
reformatting, fixing grammar problems and clarifying the correlations
between randomize-va-space, kernel parameter "norandmaps" and the
CONFIG_COMPAT_BRK option.
Signed-off-by: Horst Schirmeier <[email protected]>
---
Documentation/sysctl/kernel.txt | 30 +++++++++++++++++-------------
1 files changed, 17 insertions(+), 13 deletions(-)
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 322a00b..dd8322f 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -303,25 +303,29 @@ This option can be used to select the type of process address
space randomization that is used in the system, for architectures
that support this feature.
-0 - Turn the process address space randomization off by default.
+0 - Turn the process address space randomization off. This is the
+ default for architectures that do not support this feature anyways,
+ and kernels that are booted with the "norandmaps" parameter.
1 - Make the addresses of mmap base, stack and VDSO page randomized.
This, among other things, implies that shared libraries will be
- loaded to random addresses. Also for PIE-linked binaries, the location
- of code start is randomized.
+ loaded to random addresses. Also for PIE-linked binaries, the
+ location of code start is randomized. This is the default if the
+ CONFIG_COMPAT_BRK option is enabled.
- With heap randomization, the situation is a little bit more
- complicated.
- There a few legacy applications out there (such as some ancient
+2 - Additionally enable heap randomization. This is the default if
+ CONFIG_COMPAT_BRK is disabled.
+
+ There are a few legacy applications out there (such as some ancient
versions of libc.so.5 from 1996) that assume that brk area starts
- just after the end of the code+bss. These applications break when
- start of the brk area is randomized. There are however no known
+ just after the end of the code+bss. These applications break when
+ start of the brk area is randomized. There are however no known
non-legacy applications that would be broken this way, so for most
- systems it is safe to choose full randomization. However there is
- a CONFIG_COMPAT_BRK option for systems with ancient and/or broken
- binaries, that makes heap non-randomized, but keeps all other
- parts of process address space randomized if randomize_va_space
- sysctl is turned on.
+ systems it is safe to choose full randomization.
+
+ Systems with ancient and/or broken binaries should be configured
+ with CONFIG_COMPAT_BRK enabled, which excludes the heap from process
+ address space randomization.
==============================================================
--
PGP-Key 0xD40E0E7A
[ added Ingo to CC ]
On Fri, 3 Jul 2009, Horst Schirmeier wrote:
> On Fri, 03 Jul 2009, Jiri Kosina wrote:
> > > There a few legacy applications out there (such as some ancient
> >
> > ... would you please fix this typo/grammo as well? (There a few ...)
> >
> > > versions of libc.so.5 from 1996) that assume that brk area starts
> >
> > Also, the text itself doesn't seem to be super-clear ... namely, it
> > describes what CONFIG_COMPAT_BRK is about, but doesn't really clarify how
> > exactly does this correlate with randomize_va_space == 2. Would you mind
> > also fixing this bit?
>
> I hope I didn't misread the sources :-) Opinions?
>
> ---
>
> The documentation for /proc/sys/kernel/* does not mention the possible
> value 2 for randomize-va-space yet. While being there, doing some
> reformatting, fixing grammar problems and clarifying the correlations
> between randomize-va-space, kernel parameter "norandmaps" and the
> CONFIG_COMPAT_BRK option.
>
> Signed-off-by: Horst Schirmeier <[email protected]>
Acked-by: Jiri Kosina <[email protected]>
Ingo, will you take this through your tree?
>
> ---
> Documentation/sysctl/kernel.txt | 30 +++++++++++++++++-------------
> 1 files changed, 17 insertions(+), 13 deletions(-)
>
> diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
> index 322a00b..dd8322f 100644
> --- a/Documentation/sysctl/kernel.txt
> +++ b/Documentation/sysctl/kernel.txt
> @@ -303,25 +303,29 @@ This option can be used to select the type of process address
> space randomization that is used in the system, for architectures
> that support this feature.
>
> -0 - Turn the process address space randomization off by default.
> +0 - Turn the process address space randomization off. This is the
> + default for architectures that do not support this feature anyways,
> + and kernels that are booted with the "norandmaps" parameter.
>
> 1 - Make the addresses of mmap base, stack and VDSO page randomized.
> This, among other things, implies that shared libraries will be
> - loaded to random addresses. Also for PIE-linked binaries, the location
> - of code start is randomized.
> + loaded to random addresses. Also for PIE-linked binaries, the
> + location of code start is randomized. This is the default if the
> + CONFIG_COMPAT_BRK option is enabled.
>
> - With heap randomization, the situation is a little bit more
> - complicated.
> - There a few legacy applications out there (such as some ancient
> +2 - Additionally enable heap randomization. This is the default if
> + CONFIG_COMPAT_BRK is disabled.
> +
> + There are a few legacy applications out there (such as some ancient
> versions of libc.so.5 from 1996) that assume that brk area starts
> - just after the end of the code+bss. These applications break when
> - start of the brk area is randomized. There are however no known
> + just after the end of the code+bss. These applications break when
> + start of the brk area is randomized. There are however no known
> non-legacy applications that would be broken this way, so for most
> - systems it is safe to choose full randomization. However there is
> - a CONFIG_COMPAT_BRK option for systems with ancient and/or broken
> - binaries, that makes heap non-randomized, but keeps all other
> - parts of process address space randomized if randomize_va_space
> - sysctl is turned on.
> + systems it is safe to choose full randomization.
> +
> + Systems with ancient and/or broken binaries should be configured
> + with CONFIG_COMPAT_BRK enabled, which excludes the heap from process
> + address space randomization.
>
> ==============================================================
>
>
> --
> PGP-Key 0xD40E0E7A
>
Thanks,
--
Jiri Kosina
SUSE Labs
* Jiri Kosina <[email protected]> wrote:
>
> [ added Ingo to CC ]
>
> On Fri, 3 Jul 2009, Horst Schirmeier wrote:
>
> > On Fri, 03 Jul 2009, Jiri Kosina wrote:
> > > > There a few legacy applications out there (such as some ancient
> > >
> > > ... would you please fix this typo/grammo as well? (There a few ...)
> > >
> > > > versions of libc.so.5 from 1996) that assume that brk area starts
> > >
> > > Also, the text itself doesn't seem to be super-clear ... namely, it
> > > describes what CONFIG_COMPAT_BRK is about, but doesn't really clarify how
> > > exactly does this correlate with randomize_va_space == 2. Would you mind
> > > also fixing this bit?
> >
> > I hope I didn't misread the sources :-) Opinions?
> >
> > ---
> >
> > The documentation for /proc/sys/kernel/* does not mention the possible
> > value 2 for randomize-va-space yet. While being there, doing some
> > reformatting, fixing grammar problems and clarifying the correlations
> > between randomize-va-space, kernel parameter "norandmaps" and the
> > CONFIG_COMPAT_BRK option.
> >
> > Signed-off-by: Horst Schirmeier <[email protected]>
>
> Acked-by: Jiri Kosina <[email protected]>
>
> Ingo, will you take this through your tree?
>
> >
> > ---
> > Documentation/sysctl/kernel.txt | 30 +++++++++++++++++-------------
> > 1 files changed, 17 insertions(+), 13 deletions(-)
This could go to your or Randy's docs tree, right? (would be fine by
me)
Ingo
On Fri, 3 Jul 2009, Ingo Molnar wrote:
> > > > > There a few legacy applications out there (such as some ancient
> > > >
> > > > ... would you please fix this typo/grammo as well? (There a few ...)
> > > >
> > > > > versions of libc.so.5 from 1996) that assume that brk area starts
> > > >
> > > > Also, the text itself doesn't seem to be super-clear ... namely, it
> > > > describes what CONFIG_COMPAT_BRK is about, but doesn't really clarify how
> > > > exactly does this correlate with randomize_va_space == 2. Would you mind
> > > > also fixing this bit?
> > >
> > > I hope I didn't misread the sources :-) Opinions?
> > >
> > > ---
> > >
> > > The documentation for /proc/sys/kernel/* does not mention the possible
> > > value 2 for randomize-va-space yet. While being there, doing some
> > > reformatting, fixing grammar problems and clarifying the correlations
> > > between randomize-va-space, kernel parameter "norandmaps" and the
> > > CONFIG_COMPAT_BRK option.
> > >
> > > Signed-off-by: Horst Schirmeier <[email protected]>
> >
> > Acked-by: Jiri Kosina <[email protected]>
> >
> > Ingo, will you take this through your tree?
> >
> > >
> > > ---
> > > Documentation/sysctl/kernel.txt | 30 +++++++++++++++++-------------
> > > 1 files changed, 17 insertions(+), 13 deletions(-)
>
> This could go to your or Randy's docs tree, right? (would be fine by
> me)
Sure, I basically just wanted your ACK, as you were the last one touching
the respective code.
I will queue it, thanks.
--
Jiri Kosina
SUSE Labs