Hi,
So, I'm trying to come up to speed on what's still outstanding in the
effort to constify function pointers. I saw patches from Emese Revfy
go in, and I saw Lionel Debroux's recent patches. What already-created
work still needs attention? I know there's more code to be written,
but I'm trying to find any patches that have already been written but
have not gone upstream yet.
Thanks,
-Kees
--
Kees Cook
Ubuntu Security Team
On 11/08/10 23:38, Kees Cook wrote:
> Hi,
>
> So, I'm trying to come up to speed on what's still outstanding in the
> effort to constify function pointers. I saw patches from Emese Revfy
> go in, and I saw Lionel Debroux's recent patches. What already-created
> work still needs attention? I know there's more code to be written,
> but I'm trying to find any patches that have already been written but
> have not gone upstream yet.
Hi,
I will gladly break up my current patch for the next -rc by structure
type or maintainer (some preferred it one way or the other) and send
it in some time next week so that you can handle the upstream submission
process (I will continue to maintain my patch in grsecurity).
There are many structures that can be constified, you can use the following
command to find most of them (use it on an allyesconfig kernel preferably):
grep _ops System.map |grep -Ewi 'b|d' | awk '{print $3}' | \
while read i ; do cscope -d -L -1 $i | grep -E "struct[ \t]*([^ ]*)[ \t]*" \
--color=none -o | awk '{print $2}' ; done |sort -u
Also there are always new instances of structures going in that should have
been constified.
I tried to automate the whole process with Coccinelle but I abandoned it
because Coccinelle didn't support recursive header file inclusion at the time.
If someone feels like fixing Coccinelle then I would quickly finish my script
(it has a few bugs because I could never test it for real), but see the end
of the mail for the current version. I think it would be a good idea because
it would take a few hours only to generate a constification patch for a new
kernel. One thing that probably cannot be automated with Coccinelle is that
once the script determines that a given structure cannot be constified, it
cannot undo already emitted patches for the given structure so it must be
cleaned up by post processing script.
--
Emese
// spatch.opt -sp_file $1 -include_headers -local_includes -all_includes -I "include/" -dir $2
@initialize:python@
noconst = []
@stc@
identifier idtype, y;
type t;
position p;
@@
struct idtype {
...
t (*y)(...);@p
...
};
@notjustfp@
identifier stc.idtype, y;
type t;
position p != stc.p;
@@
struct idtype {
...
t y;@p
...
};
@script:python depends on notjustfp@
@@
cocci.include_match(False)
@variable@
identifier stc.idtype, idvariant, id;
@@
(
struct idtype idvariant = {
...
};
|
struct idtype idvariant;
|
struct idtype *idvariant;
|
struct id {
...
struct idtype idvariant;
...
};
)
@script:python@
y << variable.idvariant;
@@
if y in noconst:
cocci.include_match(False)
@alreadyconst@
identifier stc.idtype, variable.idvariant, id;
@@
(
const struct idtype idvariant;
|
const struct idtype idvariant = {
...
};
|
const struct idtype *idvariant;
|
struct id {
...
const struct idtype idvariant;
...
};
)
@script:python depends on alreadyconst@
@@
cocci.include_match(False)
@fn_declaration@
identifier stc.idtype, variable.idvariant, fn;
type t;
@@
t fn(struct idtype *idvariant);
@fn_definition@
identifier stc.idtype, variable.idvariant, fn;
type t;
@@
t fn(struct idtype *idvariant)
{
...
}
// TODO: handle var.field1.field2, var->field1->field2
@assignement@
identifier variable.idvariant, x, idptr;
@@
(
idvariant.x = ...;
|
idvariant->x = ...;
|
idptr = &idvariant;
...
idptr->x = ...;
|
memcpy(&idvariant, ...);
|
memcpy(idvariant.x, ...);
|
memcpy(idvariant->x, ...);
|
idvariant = kzalloc(...);
|
idvariant = kmalloc(...);
)
@script:python depends on assignement@
x << stc.idtype;
y << variable.idvariant;
@@
print "Cannot be const: %s-%s" % (x, y)
noconst.append(y)
cocci.include_match(False)
@depends on stc && !fn_declaration && !fn_definition@
identifier stc.idtype, variable.idvariant, id;
@@
(
-struct idtype idvariant = {
+const struct idtype idvariant = {
...
};
|
-struct idtype idvariant;
+const struct idtype idvariant;
|
-struct idtype *idvariant;
+const struct idtype *idvariant;
|
-struct idtype *idvariant = NULL;
+const struct idtype *idvariant = NULL;
|
struct id {
...
-struct idtype idvariant;
+const struct idtype idvariant;
...
};
)
@depends on stc && fn_declaration && !fn_definition@
identifier stc.idtype, variable.idvariant, fn_declaration.fn;
type fn_declaration.t;
@@
t fn(
-struct idtype *idvariant
+const struct idtype *idvariant
);
@depends on stc && !fn_declaration && fn_definition@
identifier stc.idtype, variable.idvariant, fn_definition.fn;
type fn_definition.t;
@@
t fn(
-struct idtype *idvariant
+const struct idtype *idvariant
)
{
...
}
Hi Emese,
I got distracted, but I'd like to get back to this thread...
On Tue, Nov 09, 2010 at 10:37:41PM +0100, Emese Revfy wrote:
> I will gladly break up my current patch for the next -rc by structure
> type or maintainer (some preferred it one way or the other) and send
> it in some time next week so that you can handle the upstream submission
> process (I will continue to maintain my patch in grsecurity).
>
> There are many structures that can be constified, you can use the following
> command to find most of them (use it on an allyesconfig kernel preferably):
>
> grep _ops System.map |grep -Ewi 'b|d' | awk '{print $3}' | \
> while read i ; do cscope -d -L -1 $i | grep -E "struct[ \t]*([^ ]*)[ \t]*" \
> --color=none -o | awk '{print $2}' ; done |sort -u
>
> Also there are always new instances of structures going in that should have
> been constified.
Just in my running kernel, I see 56 _ops structures reported from the above
search. :)
Do you have a new stack of patches I can help usher into the kernel? I
don't want reinvent the wheel if I don't have to. :)
> I tried to automate the whole process with Coccinelle but I abandoned it
> because Coccinelle didn't support recursive header file inclusion at the time.
> If someone feels like fixing Coccinelle then I would quickly finish my script
> (it has a few bugs because I could never test it for real), but see the end
> of the mail for the current version. I think it would be a good idea because
> it would take a few hours only to generate a constification patch for a new
> kernel. One thing that probably cannot be automated with Coccinelle is that
> once the script determines that a given structure cannot be constified, it
> cannot undo already emitted patches for the given structure so it must be
> cleaned up by post processing script.
Has there been any update to your Coccinelle script since the addition of
-recursive_includes?
Thanks!
-Kees
--
Kees Cook
Ubuntu Security Team
On Fri, 27 May 2011, Kees Cook wrote:
> Hi Emese,
>
> I got distracted, but I'd like to get back to this thread...
>
> On Tue, Nov 09, 2010 at 10:37:41PM +0100, Emese Revfy wrote:
> > I will gladly break up my current patch for the next -rc by structure
> > type or maintainer (some preferred it one way or the other) and send
> > it in some time next week so that you can handle the upstream submission
> > process (I will continue to maintain my patch in grsecurity).
> >
> > There are many structures that can be constified, you can use the following
> > command to find most of them (use it on an allyesconfig kernel preferably):
> >
> > grep _ops System.map |grep -Ewi 'b|d' | awk '{print $3}' | \
> > while read i ; do cscope -d -L -1 $i | grep -E "struct[ \t]*([^ ]*)[ \t]*" \
> > --color=none -o | awk '{print $2}' ; done |sort -u
> >
> > Also there are always new instances of structures going in that should have
> > been constified.
>
> Just in my running kernel, I see 56 _ops structures reported from the above
> search. :)
>
> Do you have a new stack of patches I can help usher into the kernel? I
> don't want reinvent the wheel if I don't have to. :)
>
> > I tried to automate the whole process with Coccinelle but I abandoned it
> > because Coccinelle didn't support recursive header file inclusion at the time.
> > If someone feels like fixing Coccinelle then I would quickly finish my script
> > (it has a few bugs because I could never test it for real), but see the end
> > of the mail for the current version. I think it would be a good idea because
> > it would take a few hours only to generate a constification patch for a new
> > kernel. One thing that probably cannot be automated with Coccinelle is that
> > once the script determines that a given structure cannot be constified, it
> > cannot undo already emitted patches for the given structure so it must be
> > cleaned up by post processing script.
Could I see the semantic patch? The clean up issue sounds interesting.
Perhaps there is a way around it.
julia
> Has there been any update to your Coccinelle script since the addition of
> -recursive_includes?
>
> Thanks!
>
> -Kees
>
> --
> Kees Cook
> Ubuntu Security Team
> _______________________________________________
> Cocci mailing list
> [email protected]
> http://lists.diku.dk/mailman/listinfo/cocci
> (Web access from inside DIKUs LAN only)
>
> Could I see the semantic patch? The clean up issue sounds interesting.
> Perhaps there is a way around it.
Hi,
I no longer use Coccinelle to generate constification patch, but only to find
candidate structures for constification. This is because I ran into several issues
some of which I will try describe now from memory (unfortunately I don't have
those Cocci scripts anymore):
1. Sometimes (always?) cocci removed NULL initialization while emitting the constified patch:
linux-2.6.39-rc7/arch/frv/mb93090-mb00/pci-vdk.c
@@ -356,7 +356,7 @@ void __init pcibios_fixup_bus(struct pci
int __init pcibios_init(void)
{
- struct pci_ops *dir = NULL;
+ const struct pci_ops *dir;
if (!mb93090_mb00_detected)
return -ENXIO;
2. Sometimes (always?) cocci joined structure field lines into one line while constifying them:
linux-2.6.39-rc7/arch/x86/include/asm/x86_init.h
@@ -119,14 +119,7 @@ struct x86_init_pci {
*
*/
struct x86_init_ops {
- struct x86_init_resources resources;
- struct x86_init_mpparse mpparse;
- struct x86_init_irqs irqs;
- struct x86_init_oem oem;
- struct x86_init_paging paging;
- struct x86_init_timers timers;
- struct x86_init_iommu iommu;
- struct x86_init_pci pci;
+ const struct x86_init_resources resources;const struct x86_init_mpparse mpparse;const struct x86_init_irqs irqs;const struct x86_init_oem oem;const struct x86_init_paging paging;const struct x86_init_timers timers;const struct x86_init_iommu iommu;const struct x86_init_pci pci;
};
/**
3. Sometimes cocci removed comment lines while joining others, maybe related
to the previous issue:
linux-2.6.39-rc7/drivers/net/wireless/ath/ath9k/hw.h
@@ -753,9 +753,7 @@ struct ath_hw {
} enable_32kHz_clock;
/* Private to hardware code */
- struct ath_hw_private_ops private_ops;
- /* Accessed by the lower level driver */
- struct ath_hw_ops ops;
+ const struct ath_hw_private_ops private_ops;const struct ath_hw_ops ops;
/* Used to program the radio on non single-chip devices */
u32 *analogBank0Data;
4. My constification patch generator cocci script didn't find all structures that it should have, I don't know whether it was a bug in my script or in cocci but in the end I just gave it up.
--
Emese
Thanks for the reports. The first is due to an isomorphism that allows a
declaration to match a declaration in which the declared variable is
assigned to a constant. You can put disable const_decl_init in your rule
to avoid this. I'll look into the disappearing newlines problem. I think
there has been some progress in this direction recently, but proper pretty
printing is an ongoing battle... I'm not sure about the last problem. If
you try again at some point, you can let me know in more detail of what
the problem is.
Thanks,
julia
On Sun, 5 Jun 2011, Emese Revfy wrote:
> > Could I see the semantic patch? The clean up issue sounds interesting.
> > Perhaps there is a way around it.
>
> Hi,
> I no longer use Coccinelle to generate constification patch, but only to find
> candidate structures for constification. This is because I ran into several
> issues
> some of which I will try describe now from memory (unfortunately I don't have
> those Cocci scripts anymore):
>
> 1. Sometimes (always?) cocci removed NULL initialization while emitting the
> constified patch:
>
> linux-2.6.39-rc7/arch/frv/mb93090-mb00/pci-vdk.c
> @@ -356,7 +356,7 @@ void __init pcibios_fixup_bus(struct pci
>
> int __init pcibios_init(void)
> {
> - struct pci_ops *dir = NULL;
> + const struct pci_ops *dir;
>
> if (!mb93090_mb00_detected)
> return -ENXIO;
>
> 2. Sometimes (always?) cocci joined structure field lines into one line while
> constifying them:
>
> linux-2.6.39-rc7/arch/x86/include/asm/x86_init.h
> @@ -119,14 +119,7 @@ struct x86_init_pci {
> *
> */
> struct x86_init_ops {
> - struct x86_init_resources resources;
> - struct x86_init_mpparse mpparse;
> - struct x86_init_irqs irqs;
> - struct x86_init_oem oem;
> - struct x86_init_paging paging;
> - struct x86_init_timers timers;
> - struct x86_init_iommu iommu;
> - struct x86_init_pci pci;
> + const struct x86_init_resources resources;const struct
> x86_init_mpparse mpparse;const struct x86_init_irqs irqs;const struct
> x86_init_oem oem;const struct x86_init_paging paging;const struct
> x86_init_timers timers;const struct x86_init_iommu iommu;const struct
> x86_init_pci pci;
> };
>
> /**
>
> 3. Sometimes cocci removed comment lines while joining others, maybe related
> to the previous issue:
> linux-2.6.39-rc7/drivers/net/wireless/ath/ath9k/hw.h
> @@ -753,9 +753,7 @@ struct ath_hw {
> } enable_32kHz_clock;
>
> /* Private to hardware code */
> - struct ath_hw_private_ops private_ops;
> - /* Accessed by the lower level driver */
> - struct ath_hw_ops ops;
> + const struct ath_hw_private_ops private_ops;const struct ath_hw_ops
> ops;
>
> /* Used to program the radio on non single-chip devices */
> u32 *analogBank0Data;
>
> 4. My constification patch generator cocci script didn't find all structures
> that it should have, I don't know whether it was a bug in my script or in
> cocci but in the end I just gave it up.
>
> --
> Emese
>
>
On Sun, 5 Jun 2011, Emese Revfy wrote:
> > Could I see the semantic patch? The clean up issue sounds interesting.
> > Perhaps there is a way around it.
>
> Hi,
> I no longer use Coccinelle to generate constification patch, but only to find
> candidate structures for constification. This is because I ran into several
> issues
> some of which I will try describe now from memory (unfortunately I don't have
> those Cocci scripts anymore):
>
> 1. Sometimes (always?) cocci removed NULL initialization while emitting the
> constified patch:
>
> linux-2.6.39-rc7/arch/frv/mb93090-mb00/pci-vdk.c
> @@ -356,7 +356,7 @@ void __init pcibios_fixup_bus(struct pci
>
> int __init pcibios_init(void)
> {
> - struct pci_ops *dir = NULL;
> + const struct pci_ops *dir;
>
> if (!mb93090_mb00_detected)
> return -ENXIO;
>
> 2. Sometimes (always?) cocci joined structure field lines into one line while
> constifying them:
>
> linux-2.6.39-rc7/arch/x86/include/asm/x86_init.h
> @@ -119,14 +119,7 @@ struct x86_init_pci {
> *
> */
> struct x86_init_ops {
> - struct x86_init_resources resources;
> - struct x86_init_mpparse mpparse;
> - struct x86_init_irqs irqs;
> - struct x86_init_oem oem;
> - struct x86_init_paging paging;
> - struct x86_init_timers timers;
> - struct x86_init_iommu iommu;
> - struct x86_init_pci pci;
> + const struct x86_init_resources resources;const struct
> x86_init_mpparse mpparse;const struct x86_init_irqs irqs;const struct
> x86_init_oem oem;const struct x86_init_paging paging;const struct
> x86_init_timers timers;const struct x86_init_iommu iommu;const struct
> x86_init_pci pci;
> };
This problem seem to be solved. At least, I don't see the problem for the
following semantic patch:
@@
identifier i,x;
type T;
@@
struct i {
...
- T x;
+ const T x;
...
};
on the following code:
struct i {
int a;
int b;
/* a comment */
int c;
int d;
};
The comment is preserved as well.
julia
> /**
>
> 3. Sometimes cocci removed comment lines while joining others, maybe related
> to the previous issue:
> linux-2.6.39-rc7/drivers/net/wireless/ath/ath9k/hw.h
> @@ -753,9 +753,7 @@ struct ath_hw {
> } enable_32kHz_clock;
>
> /* Private to hardware code */
> - struct ath_hw_private_ops private_ops;
> - /* Accessed by the lower level driver */
> - struct ath_hw_ops ops;
> + const struct ath_hw_private_ops private_ops;const struct ath_hw_ops
> ops;
>
> /* Used to program the radio on non single-chip devices */
> u32 *analogBank0Data;
>
> 4. My constification patch generator cocci script didn't find all structures
> that it should have, I don't know whether it was a bug in my script or in
> cocci but in the end I just gave it up.
>
> --
> Emese
>
>
> This problem seem to be solved. At least, I don't see the problem for the
> following semantic patch:
>
> @@
> identifier i,x;
> type T;
> @@
>
> struct i {
> ...
> - T x;
> + const T x;
> ...
> };
>
> on the following code:
>
> struct i {
> int a;
> int b;
> /* a comment */
> int c;
> int d;
> };
>
> The comment is preserved as well.
Hi,
I've just noticed there is a new version out (1.0.0-rc3), I will give it a try and let you know
the results.
--
Emese