diff mbox

[v3] audit: Add generic compat syscall support

Message ID 1389945795-4255-2-git-send-email-takahiro.akashi@linaro.org
State New
Headers show

Commit Message

AKASHI Takahiro Jan. 17, 2014, 8:03 a.m. UTC
lib/audit.c provides a generic definition for auditing system calls.
This patch extends it for compat syscall support on bi-architectures
(32/64-bit) by adding lib/compat_audit.c when CONFIG_COMPAT enabled.

Each architecture that wants to use this must define audit_is_compat()
in asm/audit.h.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
---
 include/linux/audit.h |    9 +++++++++
 lib/Makefile          |    3 +++
 lib/audit.c           |   17 +++++++++++++++++
 lib/compat_audit.c    |   51 +++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 80 insertions(+)
 create mode 100644 lib/compat_audit.c

Comments

Catalin Marinas Jan. 23, 2014, 2:51 p.m. UTC | #1
On Fri, Jan 17, 2014 at 08:03:15AM +0000, AKASHI Takahiro wrote:
> lib/audit.c provides a generic definition for auditing system calls.
> This patch extends it for compat syscall support on bi-architectures
> (32/64-bit) by adding lib/compat_audit.c when CONFIG_COMPAT enabled.
> 
> Each architecture that wants to use this must define audit_is_compat()
> in asm/audit.h.
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

I'm not familiar with the audit subsystem but I have some (cosmetic)
comments below.

> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index bf1ef22..3d71949 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -78,6 +78,15 @@ extern int is_audit_feature_set(int which);
>  extern int __init audit_register_class(int class, unsigned *list);
>  extern int audit_classify_syscall(int abi, unsigned syscall);
>  extern int audit_classify_arch(int arch);
> +#if defined(CONFIG_AUDIT_GENERIC) && defined(CONFIG_COMPAT)
> +extern unsigned compat_write_class[];
> +extern unsigned compat_read_class[];
> +extern unsigned compat_dir_class[];
> +extern unsigned compat_chattr_class[];
> +extern unsigned compat_signal_class[];
> +
> +extern int audit_classify_compat_syscall(int abi, unsigned syscall);
> +#endif
>  
>  /* audit_names->type values */
>  #define	AUDIT_TYPE_UNKNOWN	0	/* we don't know yet */
> diff --git a/lib/Makefile b/lib/Makefile
> index a459c31..73ea908 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -93,6 +93,9 @@ obj-$(CONFIG_TEXTSEARCH_BM) += ts_bm.o
>  obj-$(CONFIG_TEXTSEARCH_FSM) += ts_fsm.o
>  obj-$(CONFIG_SMP) += percpu_counter.o
>  obj-$(CONFIG_AUDIT_GENERIC) += audit.o
> +ifeq ($(CONFIG_COMPAT),y)
> +obj-$(CONFIG_AUDIT_GENERIC) += compat_audit.o
> +endif

You could use a CONFIG_AUDIT_COMPAT_GENERIC and simplify other #ifdefs
as well.

> --- a/lib/audit.c
> +++ b/lib/audit.c
> @@ -1,6 +1,7 @@
>  #include <linux/init.h>
>  #include <linux/types.h>
>  #include <linux/audit.h>
> +#include <asm/audit.h>
>  #include <asm/unistd.h>
>  
>  static unsigned dir_class[] = {
> @@ -30,11 +31,20 @@ static unsigned signal_class[] = {
>  
>  int audit_classify_arch(int arch)
>  {
> +#ifdef CONFIG_COMPAT
> +	if (audit_is_compat(arch))
> +		return 1;
> +#endif
>  	return 0;
>  }

Here and in other places, just define a default audit_is_compat()
functions which returns false when !CONFIG_COMPAT to avoid the #ifdefs.

> diff --git a/lib/compat_audit.c b/lib/compat_audit.c
> new file mode 100644
> index 0000000..94f6480
> --- /dev/null
> +++ b/lib/compat_audit.c
> @@ -0,0 +1,51 @@
> +#include <linux/init.h>
> +#include <linux/types.h>
> +/* FIXME: this might be architecture dependent */
> +#include <asm/unistd_32.h>

It most likely is architecture dependent.

> +int audit_classify_compat_syscall(int abi, unsigned syscall)
> +{
> +	switch (syscall) {
> +#ifdef __NR_open
> +	case __NR_open:
> +		return 2;
> +#endif
> +#ifdef __NR_openat
> +	case __NR_openat:
> +		return 3;
> +#endif
> +#ifdef __NR_socketcall
> +	case __NR_socketcall:
> +		return 4;
> +#endif
> +	case __NR_execve:
> +		return 5;
> +	default:
> +		return 1;
> +	}
> +}

BTW, since they aren't many, you could get the arch code to define
__NR_compat_open etc. explicitly and use these. On arm64 we have a few
of these defined to avoid name collision in signal handling code.
AKASHI Takahiro Jan. 27, 2014, 5:58 a.m. UTC | #2
Catalin and audit maintainers,

On 01/23/2014 11:51 PM, Catalin Marinas wrote:
> On Fri, Jan 17, 2014 at 08:03:15AM +0000, AKASHI Takahiro wrote:
>> lib/audit.c provides a generic definition for auditing system calls.
>> This patch extends it for compat syscall support on bi-architectures
>> (32/64-bit) by adding lib/compat_audit.c when CONFIG_COMPAT enabled.
>>
>> Each architecture that wants to use this must define audit_is_compat()
>> in asm/audit.h.
>>
>> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
>
> I'm not familiar with the audit subsystem but I have some (cosmetic)
> comments below.
>
>> diff --git a/include/linux/audit.h b/include/linux/audit.h
>> index bf1ef22..3d71949 100644
>> --- a/include/linux/audit.h
>> +++ b/include/linux/audit.h
>> @@ -78,6 +78,15 @@ extern int is_audit_feature_set(int which);
>>   extern int __init audit_register_class(int class, unsigned *list);
>>   extern int audit_classify_syscall(int abi, unsigned syscall);
>>   extern int audit_classify_arch(int arch);
>> +#if defined(CONFIG_AUDIT_GENERIC) && defined(CONFIG_COMPAT)
>> +extern unsigned compat_write_class[];
>> +extern unsigned compat_read_class[];
>> +extern unsigned compat_dir_class[];
>> +extern unsigned compat_chattr_class[];
>> +extern unsigned compat_signal_class[];
>> +
>> +extern int audit_classify_compat_syscall(int abi, unsigned syscall);
>> +#endif
>>
>>   /* audit_names->type values */
>>   #define	AUDIT_TYPE_UNKNOWN	0	/* we don't know yet */
>> diff --git a/lib/Makefile b/lib/Makefile
>> index a459c31..73ea908 100644
>> --- a/lib/Makefile
>> +++ b/lib/Makefile
>> @@ -93,6 +93,9 @@ obj-$(CONFIG_TEXTSEARCH_BM) += ts_bm.o
>>   obj-$(CONFIG_TEXTSEARCH_FSM) += ts_fsm.o
>>   obj-$(CONFIG_SMP) += percpu_counter.o
>>   obj-$(CONFIG_AUDIT_GENERIC) += audit.o
>> +ifeq ($(CONFIG_COMPAT),y)
>> +obj-$(CONFIG_AUDIT_GENERIC) += compat_audit.o
>> +endif
>
> You could use a CONFIG_AUDIT_COMPAT_GENERIC and simplify other #ifdefs
> as well.

I will add the following in lib/Kconfig:

   config AUDIT_COMPAT_GENERIC
     depends on AUDIT_GENERIC & COMPAT
     default y

>> --- a/lib/audit.c
>> +++ b/lib/audit.c
>> @@ -1,6 +1,7 @@
>>   #include <linux/init.h>
>>   #include <linux/types.h>
>>   #include <linux/audit.h>
>> +#include <asm/audit.h>
>>   #include <asm/unistd.h>
>>
>>   static unsigned dir_class[] = {
>> @@ -30,11 +31,20 @@ static unsigned signal_class[] = {
>>
>>   int audit_classify_arch(int arch)
>>   {
>> +#ifdef CONFIG_COMPAT
>> +	if (audit_is_compat(arch))
>> +		return 1;
>> +#endif
>>   	return 0;
>>   }
>
> Here and in other places, just define a default audit_is_compat()
> functions which returns false when !CONFIG_COMPAT to avoid the #ifdefs.

OK. With Richard's comment, the definition below will be added
to uapi/linux/audit.h:

   #ifdef CONFIG_COMPAT
   #define audit_is_compat(arch)  (!!((arch) & __AUDIT_ARCH_64BIT))
   #else
   #define audit_is_compat(arch)  false
   #endif

>> diff --git a/lib/compat_audit.c b/lib/compat_audit.c
>> new file mode 100644
>> index 0000000..94f6480
>> --- /dev/null
>> +++ b/lib/compat_audit.c
>> @@ -0,0 +1,51 @@
>> +#include <linux/init.h>
>> +#include <linux/types.h>
>> +/* FIXME: this might be architecture dependent */
>> +#include <asm/unistd_32.h>
>
> It most likely is architecture dependent.

I'm wondering what name is the most appropriate in this case.
Most archictures have __NR_xyz definitions in "unistd_32.h",
but arm64 doesn't have it, instead "unistd32." which contains
only __SYSCALL(xyz, NO). Confusing?

>> +int audit_classify_compat_syscall(int abi, unsigned syscall)
>> +{
>> +	switch (syscall) {
>> +#ifdef __NR_open
>> +	case __NR_open:
>> +		return 2;
>> +#endif
>> +#ifdef __NR_openat
>> +	case __NR_openat:
>> +		return 3;
>> +#endif
>> +#ifdef __NR_socketcall
>> +	case __NR_socketcall:
>> +		return 4;
>> +#endif
>> +	case __NR_execve:
>> +		return 5;
>> +	default:
>> +		return 1;
>> +	}
>> +}
>
> BTW, since they aren't many, you could get the arch code to define
> __NR_compat_open etc. explicitly and use these. On arm64 we have a few
> of these defined to avoid name collision in signal handling code.

Again, most architecture have their own unistd32.h for compat system calls,
and use __NR_open-like naming.
It's unlikely for these archs to migrate to "generic compat" auditing,
but I believe that '__NR_open'-like naming is better because we may be able to avoid
arch-specific changes even for future(?) syscall-related enhancements in audit.

But, anyway, it's up to audit maintainer's preference.

Thanks,
-Takahiro AKASHI
Catalin Marinas Jan. 27, 2014, 12:15 p.m. UTC | #3
On Mon, Jan 27, 2014 at 05:58:07AM +0000, AKASHI Takahiro wrote:
> Catalin and audit maintainers,
> 
> On 01/23/2014 11:51 PM, Catalin Marinas wrote:
> > On Fri, Jan 17, 2014 at 08:03:15AM +0000, AKASHI Takahiro wrote:
> >> diff --git a/lib/compat_audit.c b/lib/compat_audit.c
> >> new file mode 100644
> >> index 0000000..94f6480
> >> --- /dev/null
> >> +++ b/lib/compat_audit.c
> >> @@ -0,0 +1,51 @@
> >> +#include <linux/init.h>
> >> +#include <linux/types.h>
> >> +/* FIXME: this might be architecture dependent */
> >> +#include <asm/unistd_32.h>
> >
> > It most likely is architecture dependent.
> 
> I'm wondering what name is the most appropriate in this case.
> Most archictures have __NR_xyz definitions in "unistd_32.h",
> but arm64 doesn't have it, instead "unistd32." which contains
> only __SYSCALL(xyz, NO). Confusing?

I don't think we should introduce a new file (or at least it should be
named something containing "audit" to make it clearer).

> >> +int audit_classify_compat_syscall(int abi, unsigned syscall)
> >> +{
> >> +	switch (syscall) {
> >> +#ifdef __NR_open
> >> +	case __NR_open:
> >> +		return 2;
> >> +#endif
> >> +#ifdef __NR_openat
> >> +	case __NR_openat:
> >> +		return 3;
> >> +#endif
> >> +#ifdef __NR_socketcall
> >> +	case __NR_socketcall:
> >> +		return 4;
> >> +#endif
> >> +	case __NR_execve:
> >> +		return 5;
> >> +	default:
> >> +		return 1;
> >> +	}
> >> +}
> >
> > BTW, since they aren't many, you could get the arch code to define
> > __NR_compat_open etc. explicitly and use these. On arm64 we have a few
> > of these defined to avoid name collision in signal handling code.
> 
> Again, most architecture have their own unistd32.h for compat system calls,
> and use __NR_open-like naming.
> It's unlikely for these archs to migrate to "generic compat" auditing,
> but I believe that '__NR_open'-like naming is better because we may be able to avoid
> arch-specific changes even for future(?) syscall-related enhancements in audit.

My preference is as above, a few __NR_compat_* (just those required by
audit) defined in unistd.h but I'm not an audit maintainer.
AKASHI Takahiro Jan. 29, 2014, 5:58 a.m. UTC | #4
Catalin,

Let me correct myself,

On 01/27/2014 09:15 PM, Catalin Marinas wrote:
> On Mon, Jan 27, 2014 at 05:58:07AM +0000, AKASHI Takahiro wrote:
>> Catalin and audit maintainers,
>>
>> On 01/23/2014 11:51 PM, Catalin Marinas wrote:
>>> On Fri, Jan 17, 2014 at 08:03:15AM +0000, AKASHI Takahiro wrote:
>>>> diff --git a/lib/compat_audit.c b/lib/compat_audit.c
>>>> new file mode 100644
>>>> index 0000000..94f6480
>>>> --- /dev/null
>>>> +++ b/lib/compat_audit.c
>>>> @@ -0,0 +1,51 @@
>>>> +#include <linux/init.h>
>>>> +#include <linux/types.h>
>>>> +/* FIXME: this might be architecture dependent */
>>>> +#include <asm/unistd_32.h>
>>>
>>> It most likely is architecture dependent.
>>
>> I'm wondering what name is the most appropriate in this case.
>> Most archictures have __NR_xyz definitions in "unistd_32.h",
>> but arm64 doesn't have it, instead "unistd32." which contains
>> only __SYSCALL(xyz, NO). Confusing?
>
> I don't think we should introduce a new file (or at least it should be
> named something containing "audit" to make it clearer).
>
>>>> +int audit_classify_compat_syscall(int abi, unsigned syscall)
>>>> +{
>>>> +	switch (syscall) {
>>>> +#ifdef __NR_open
>>>> +	case __NR_open:
>>>> +		return 2;
>>>> +#endif
>>>> +#ifdef __NR_openat
>>>> +	case __NR_openat:
>>>> +		return 3;
>>>> +#endif
>>>> +#ifdef __NR_socketcall
>>>> +	case __NR_socketcall:
>>>> +		return 4;
>>>> +#endif
>>>> +	case __NR_execve:
>>>> +		return 5;
>>>> +	default:
>>>> +		return 1;
>>>> +	}
>>>> +}
>>>
>>> BTW, since they aren't many, you could get the arch code to define
>>> __NR_compat_open etc. explicitly and use these. On arm64 we have a few
>>> of these defined to avoid name collision in signal handling code.
>>
>> Again, most architecture have their own unistd32.h for compat system calls,
>> and use __NR_open-like naming.
>> It's unlikely for these archs to migrate to "generic compat" auditing,
>> but I believe that '__NR_open'-like naming is better because we may be able to avoid
>> arch-specific changes even for future(?) syscall-related enhancements in audit.

In my compat_audit.c, all the entries in audit classes are derived from asm-generic/audit_*.h,
where __NR_xyz are used to list the system calls. So it is not possible to use __NR_compat_xyz
as far as we re-use those generic files.
(Obviously we don't want to duplicate those header files, that is, audit_compat_*.h.)

I agree that we should not have similar but different files, like unist32.h and unistd_32.h,
but it seems to be inevitable for our case. (That is the reason why I dynamically generate unistd_32.h)

As for arch-specific header file name, "audit_unistd32.h" can be fine, but people on other architectures
might be unhappy with such a name since they can commonly use unistd32.h instead.


- Takahiro AKASHI

> My preference is as above, a few __NR_compat_* (just those required by
> audit) defined in unistd.h but I'm not an audit maintainer.
>
diff mbox

Patch

diff --git a/include/linux/audit.h b/include/linux/audit.h
index bf1ef22..3d71949 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -78,6 +78,15 @@  extern int is_audit_feature_set(int which);
 extern int __init audit_register_class(int class, unsigned *list);
 extern int audit_classify_syscall(int abi, unsigned syscall);
 extern int audit_classify_arch(int arch);
+#if defined(CONFIG_AUDIT_GENERIC) && defined(CONFIG_COMPAT)
+extern unsigned compat_write_class[];
+extern unsigned compat_read_class[];
+extern unsigned compat_dir_class[];
+extern unsigned compat_chattr_class[];
+extern unsigned compat_signal_class[];
+
+extern int audit_classify_compat_syscall(int abi, unsigned syscall);
+#endif
 
 /* audit_names->type values */
 #define	AUDIT_TYPE_UNKNOWN	0	/* we don't know yet */
diff --git a/lib/Makefile b/lib/Makefile
index a459c31..73ea908 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -93,6 +93,9 @@  obj-$(CONFIG_TEXTSEARCH_BM) += ts_bm.o
 obj-$(CONFIG_TEXTSEARCH_FSM) += ts_fsm.o
 obj-$(CONFIG_SMP) += percpu_counter.o
 obj-$(CONFIG_AUDIT_GENERIC) += audit.o
+ifeq ($(CONFIG_COMPAT),y)
+obj-$(CONFIG_AUDIT_GENERIC) += compat_audit.o
+endif
 
 obj-$(CONFIG_SWIOTLB) += swiotlb.o
 obj-$(CONFIG_IOMMU_HELPER) += iommu-helper.o
diff --git a/lib/audit.c b/lib/audit.c
index 76bbed4..e29ba82 100644
--- a/lib/audit.c
+++ b/lib/audit.c
@@ -1,6 +1,7 @@ 
 #include <linux/init.h>
 #include <linux/types.h>
 #include <linux/audit.h>
+#include <asm/audit.h>
 #include <asm/unistd.h>
 
 static unsigned dir_class[] = {
@@ -30,11 +31,20 @@  static unsigned signal_class[] = {
 
 int audit_classify_arch(int arch)
 {
+#ifdef CONFIG_COMPAT
+	if (audit_is_compat(arch))
+		return 1;
+#endif
 	return 0;
 }
 
 int audit_classify_syscall(int abi, unsigned syscall)
 {
+#ifdef CONFIG_COMPAT
+	if (audit_is_compat(abi))
+		return audit_classify_compat_syscall(abi, syscall);
+#endif
+
 	switch(syscall) {
 #ifdef __NR_open
 	case __NR_open:
@@ -57,6 +67,13 @@  int audit_classify_syscall(int abi, unsigned syscall)
 
 static int __init audit_classes_init(void)
 {
+#ifdef CONFIG_COMPAT
+	audit_register_class(AUDIT_CLASS_WRITE_32, compat_write_class);
+	audit_register_class(AUDIT_CLASS_READ_32, compat_read_class);
+	audit_register_class(AUDIT_CLASS_DIR_WRITE_32, compat_dir_class);
+	audit_register_class(AUDIT_CLASS_CHATTR_32, compat_chattr_class);
+	audit_register_class(AUDIT_CLASS_SIGNAL_32, compat_signal_class);
+#endif
 	audit_register_class(AUDIT_CLASS_WRITE, write_class);
 	audit_register_class(AUDIT_CLASS_READ, read_class);
 	audit_register_class(AUDIT_CLASS_DIR_WRITE, dir_class);
diff --git a/lib/compat_audit.c b/lib/compat_audit.c
new file mode 100644
index 0000000..94f6480
--- /dev/null
+++ b/lib/compat_audit.c
@@ -0,0 +1,51 @@ 
+#include <linux/init.h>
+#include <linux/types.h>
+/* FIXME: this might be architecture dependent */
+#include <asm/unistd_32.h>
+
+unsigned compat_dir_class[] = {
+#include <asm-generic/audit_dir_write.h>
+~0U
+};
+
+unsigned compat_read_class[] = {
+#include <asm-generic/audit_read.h>
+~0U
+};
+
+unsigned compat_write_class[] = {
+#include <asm-generic/audit_write.h>
+~0U
+};
+
+unsigned compat_chattr_class[] = {
+#include <asm-generic/audit_change_attr.h>
+~0U
+};
+
+unsigned compat_signal_class[] = {
+#include <asm-generic/audit_signal.h>
+~0U
+};
+
+int audit_classify_compat_syscall(int abi, unsigned syscall)
+{
+	switch (syscall) {
+#ifdef __NR_open
+	case __NR_open:
+		return 2;
+#endif
+#ifdef __NR_openat
+	case __NR_openat:
+		return 3;
+#endif
+#ifdef __NR_socketcall
+	case __NR_socketcall:
+		return 4;
+#endif
+	case __NR_execve:
+		return 5;
+	default:
+		return 1;
+	}
+}